The future of the helicopter is electric.

[Benet]

Just thinking out of the box...

If you take a Robinson R22 and remove the Lycoming engine, battery, alternator, drive shafts, clutch, belts, and both gearboxes, fuel tanks, how much does the unpowered fuselage weigh?

Now, if you replace all of those components with a pair of DC electric motors - a big one driving the main rotor and a little one in the tail - control equipment and as many Lithium-Ion batteries as you could carry up to the same weight, how much endurance would the resulting eco-friendly machine have?

I'm not an engineer, and I don't have ready access to the numbers, but I know that:

- Electric motors are a lot lighter than piston engines
- Electric motors are way more efficient
- Startup, shutdown and carb icing wouldn't be problems any more
- There would be a lot less moving parts, and reliability would be increased
- The end result would be eco-friendly and very cheap to run!

However...

- Avgas has *much* higher energy density than, say, lithium-ion batteries
(this is probably the showstopper - figures, anyone?)
- Power and control systems would be critical to safe flight

If we get the weight & balance right, who's up for a ride in the result??

Benet

[Thomas coupling]

Excellent idea, now if you also change the dynamic weights on just one of the blades to cause a slight imbalance...you have your very own cafe latte whisker:D :D :D

[CRAN]

Benet,

I suggest that you have a look at the current electric radio controlled helicopters beginning to enter the market. They do not rely on Li-Cells but on a new type of cell that have a greatly improved power-density (the name escapes me). These machines have an endurance of about 7 minutes. WOW!

The all-electric-rotorcraft is not a new idea, the combination of modern gas turbines with shaft mounted integral high-speed electrical generators powering electrical motors via power-electronics has been bounced around by most of the big companies for years. Interestingly, the major motivation of this move would be an increase in system reliability rather than a performance/weight benefit. We are currently waiting for the technology to catch up with the concept, then i'm sure this stuff will start to make an appearance in the aircraft.

Hope this helps,
CRAN
:cool:

[Lu Zuckerman]

There is a man here in Canada that is working in conjunction with Siemans or one of their subsidiaries to use a motor that is powered by magnetic energy that is self contained and does not need an external electrical force. From what he told me this type of motor has already been developed now all they have to do is scale it up to power an aircraft or a helicopter.

:E :E

[Dave_Jackson]

Helicopter - Coaxial - Electric Motor Located between Rotors (http://www.unicopter.com/0812.html)

[Benet]

Now come on Lu... this sounds like the magic water-powered car one reads about on some forums. In order to do any useful work a motor has to get energy from somewhere.

Moreover I hoped you might be able to chip in with a bit of the engineering knowledge, such as the weights of components I mentioned. Any chance? Then we can know how much weight we've got to play with!

Cran: I'm not aiming to develop a hybrid, where electric motors are used purely for transmission. We have hybrid cars nowadays - to my mind they are horribly over-engineered.

I'm hoping someone with knowledge of battery systems can throw in some numbers as well. I've read that Li-ion batteries store about 120 watt/hours per kg, for starters...

Benet

[vorticey]

i would think that the weight of the batteries involved is the problem and the time spent "hot recharging" could be an issue aswell.
your 120w / kg battery would have the same performance as the engine in my car if it weighed 1000kg's
also im pretty sure 120watts per hour is 2 watts per minute if you want it to last for the hour. (120w for 1 minute)
i dont know if i am correct but im sure somone does :confused:

[Jcooper]

Li-poly and Li-ion batteries are great but they are very finicky. If you charge them wrong, too hot, too quickly, they have a tendency to catch fire very quickly. Also they would get extremely hot pumping out the juice required for your two electric motors.

[RDRickster]

Batteries = TOO MUCH WEIGHT & DANGER

If, in the distant future, this were to be useful - you would need to do it via fuel cell technology. The problem, within the limits of TODAY'S capabilities, is that you simply can't carry enough H2. I've read some interesting research on microfibers that allow you to trap more H2 molecules, hence increasing the amount of H2 you can carry in one cylinder. Still, I think it will be 20-30 years before something efficient is put together.

[Lu Zuckerman]

If you have ever cranked up a Bell helicopter with the battery in the nose you will have noted the spinning of the magnetic compass. Is it possible that you will have the same effect but on a continuous basis if you power the driveline with DC motors.

:E :confused: :E

[Ascend Charlie]

Imagine the helo landing next to the bowser and asking for 37 Coulombs of electrons, please.

The problem with electric motors is how to store the electrons. We all know that only round electrons can roll through wires, but they are not easily stacked up.

Flat electrons are stacked into batteries, but need a convertor to change their shape into round electrons to get into the wires. So, will this helicopter run on round or flat?

And what if, by accident, some of the coloured electrons (which normally run around in neon signs) get into the engine? Will it leave coloured trails in the sky? Might be handy for airshows, though...:8

[moosp]

A.C., they would surely have to be round ones, otherwise you would get an interrupt in the rotation of the blades as the corners of the flat ones got caught in the power cable.

It may be possible to use tape wire (like you see down the side of a building as a lightning conductor) to avoid the need for a converter to change them.

I believe that it is possible to de-colour them. There is a chap here who makes good money taking the colour out of the diesel he buys in China, so the same principle could be applied.

You see, all it needs is Good Science, and Rotorheads can solve all these technical problems. :D

[Arm out the window]

You guys are barking up the wrong tree.
Obviously the batteries are the sticking point; too heavy, too dangerous, so get rid of 'em - use a mains outlet and a very, very long extension cord.

[John Eacott]

AC,

You've obviously been in contact with the fellow in Vancouver, who has made some startling breakthroughs in his development of oval electrons? Could be the interface that you are looking for.

Not sure how they affect the colouration aspect, though. Could be they will be up into the ultra violet spectrum, and only cause distress to pets, rather than the public.

[empty pockets]

in the motoring supplement of yesterday's sunday times there is an article regarding an attempt at the electric-land speed record. using a new type of battery [radial cell??] they hope to break the 300mph limit, but the batteries are only good for 7 minutes or so.

[HOSS 1]

Just to let you know, that this has been done.

Back in the 80's Orlando Helicopters (the group that created the WhisperJet and Hummingbird kit) successfully flew a Sikorsky S-52 (HO5S-1) on battery power. I believe they were using lead-acid batteries and a torpedo motor. I'm sure it was a pretty short flight, but proved (?) the concept.



BTW, Do you really think they're keeping it up for seven minutes, or does it just seem like seven minutes? ;)

HOSS-1

[vorticey]

nasa have actualy just developed new wire cable to convert the flat electrons into round ones, by narrowing the cable down (like a funnel) it squashes them into a ball which greatly increases the rate at which work can be done. the angle of narrowing (commonly called phase angle) and the use of fully ridgid insulation that goes hard after its heated, seems to be the winning factor.

:E

[moosp]

Vorticey, I guess nasa is the Northern Australian Science Academy.

I understand that their research into the conductivity of large piles of empty tinnies, when wired to the mains to stop urinators has received high acclaim, as far afield as Tennant Creek. :D

[Dave_Jackson]

An all-plastic battery (http://www.jhu.edu/~jhumag/0297web/scitech.html#battery)

[Aviat_Consulting]

everyone that has done formal training knows that the electron's name is phil and they even made a film about him. what he does is throw his body forward down the line and his feet follow. this is different to the french belief in holes and it moves in the opp direction.Colouris just the shirt that phil is wearing at the time.

[delta3]

My craizy theory is that for more than 30 years Oil companies have (partially) sponsored battery research projects in the car industry to make shure we would still use lots of fosil fuels, because batteries simply are not the answer.
One of the interesting research outcomes is for instance that using a small solar panel, driving a little fan can efficiently cool the car in the summer on the parking : bid deal ...

A small calculation shows how inefficient batteries are :

A diesel can get 30-38% effficiency.
A fosile power plant max 38%, Nuclear because of safety 33%, say average 35%
Transmission efficiency is 95%, battery loading 95%, electrical motor efficiency 90%.
Together : 35%*95%*95%*90%= 28%
Storage, distribution of fuel is far easier, the current power system simply cannot transport these amounts, certainly not if peak power is wanted (for charging).

The remaining 60% in cars and helicopters is also used for heating, so the total 'co-generation' efficiency is higher than 30-38%, I would say by at least 5%, certainly in helicopters where you tend to encounter colder air.

Ecologically speaking : what to do with all the cupper and most important the batteries that are far from ecological.

I would stick to a diesel.

[Benet]

Thanks for your thoughts everyone, but there are some real misconceptions here which need looking at. Delta3 makes a point about transmission efficiency which is fair enough but his numbers come from... well, the top of his head probably.

A coal-fired power station is several times more efficient than a coal-fired steam engine, easily overcoming the transmission loss from high-tension cables. The same goes for any other type of primary fuel. The fact that batteries are a 'secondary' power source is simply not a problem from an efficiency point of view.

His point about electric car development is partially true. Ford and GM are busy recalling and scrapping the electric vehicles they designed for California beacause they're too good.

Instead we have the idea of hydrogen as a scondary fuel. Now this is a seriously flawed, and plenty of people believe the fuel-cell is a deliberate diversion by the oil industry.

Further reading at EV World article (http://www.evworld.com/view.cfm?section=article&storyid=691)

Hoss 1's story about the Orlando experiment is the best lead so far.... care to tell us more, Hoss 1?

Benet

[calfoote]

Benet,

I saw your posting for the first time last night. I am in the camp that say that present battery technology is what limits your idea from being applied.

I did have a look on the net to see what the performance figures for rechargeable batteries were. Some recent research anticipates an energy density of about 1000Kj/Kg (a very rough guide).

Suppose an R22 needs 90 hp (or 67 Kw) of power to cruise and supposing these batteries weigh what a full load of fuel would weigh in an R22: 81 Kg. Then you have on board 81000 Kj of energy which your motor would use at a rate of 67 Kj per second. You have power to cruise for 81000/67=1209 seconds or just over 20 minutes.

A seven or eightfold increase in battery energy density is needed before the idea becomes practical, I would guess.

[handyandyuk]

Ok, so bypassing the flat/round electron arguments on this one (although personally I'd think flat ones would be more practical purely on storage grounds), the main restriction point on this one would seem to be battery technology.
So.... in a car, the battery is used to provide energy to operate the starter and then as a constantly topped up reservoir for all other electrical usage (assuming the alternator is working).
So (2)... why not have this E22 or R22e set up to have two drive motors (both driving a main gb as per a normal twin) and also driving a pair of (or just one) high output alternators. You'd still have batteries, but only sufficient storage to run up to initial speed until the alts took over and also provide say 5 mins power should both alts fail - thus enough for say 2 mins emergency manouvering or to get safely into auto.
Granted, the oil companies would do everything possible to avoid the idea getting anywhere, but once it got certified, even with a slightly higher initial cost, I could see them selling very well indeed..... no fuel costs, massively reduced engine maint costs... the pollution bonus, the noise bonus. Potentially, could do masses for the whole helo industry.

But that's just my 2 penneth, not that I don't love the smell of avtur in the morning.... cos I don't:*

[Dave_Jackson]

Decreasing the weight of the fuselage, the rotor and the power-train by using plastics (composite construction) will be a significant improvement.

Combining this with the previously mentioned plastic battery, and one can envision the eventual possibility of the fuselage being the battery.

:8

[RDRickster]

Maybe I'm being too narrow minded, but I just don't think you will ever see batteries (stored energy using inverters or whatever similar gadget) as the primary power source for rotorcraft. You might get away with that for fixed wing, because they can turn the prop on and off when needed (& they can generally carry more weight). If it's going to happen in a rotorcraft, my money is on a hydrogen system that provides energy directly to a fuel cell, which provides power for the electric motor and systems. Again, fuel cell technology is coming along nicely... how to carry enough hydrogen (safely) is the real problem.

Heck, you can purchase a retail version of a fuel cell power generator that will provide 1,000 watts of electricity as long as hydrogen gas is supplied. It's quite, nearly maintenance free, and was designed to run INDOORS (you don't have to worry about CO poisoning in the cockpit)...

http://www.fuelcellstore.com/cgi-bin/fuelweb/view=Item/cat=94/product=393

http://www.ballard.com/popup_airgen_virtual_tour.htm

So, how can you carry enough H2 fuel (read throughput) for the larger systems (currently used in Ford & Chrystler protypes)? For rotorcraft, it just can't be done... today. That's just one challenge. With this kind of configuration, it is likely that you will need a complicated transmission to maintain RRPM in all fight regimes... simply adding more power or less power might not be an option anymore.

[NickLappos]

benet,
you are pretty far off in all of your opening premises:

- Electric motors are a lot lighter than piston engines

Not at all true. Typical piston engines are about 1/3 the weight of an equivilent electric motor. For example, a 150 HP electric motor weighs 1350 lbs, while a 180 HP Lycoming weighs 257 lbs. Even if we assume that we could get an electric motor to trim 3/4 of its weight, it would still be far heavier than a piston engine.
here are some facts
http://www.lycoming.textron.com/main.jsp?bodyPage=productSales/engineSelectionGuide/heli.html

http://www.tecowestinghouse.com/PDF/Prem_Eff_ODP(05.03).pdf

- Electric motors are way more efficient
Hardly electric motors are not engines, they are actually a form of transmission. they need raw energy to work, unlike engines, which create energy in their process. Since you don't include how the electricity is made into your assumption, you believe that the electric motor wastes less, but that is actually quite false. since someone somewhere had to make the electricity, you must count that inefficiency in, and so far, no total process is much more efficient than a simple engine. Fuel cells are the exception, and should they work out in high capacity, there might be parity in the efficiency, but of course, the weight of the fuel cell must be counted in, and they are quite heavy in high power designs, so far.

- Startup, shutdown and carb icing wouldn't be problems any more
True, but then we'd have "relay freeze" or "spark jump" or some other set of problems! Remember what the side of Apollo 13 looked like when the fuel cell exploded?

- There would be a lot less moving parts, and reliability would be increased
See Above!

- The end result would be eco-friendly and very cheap to run!
Eco-Friendly, right. And cleaner clothes, smoother white teeth, with that fresh lemon scent!

The solution to electric air vehicles is very far off, mostly weight problems, mostly in the energy storage area. Fuel cells are the best solution, along with very light weight motors and lots and lots of development time and money.

A more likely solution is to make cheap electric power with reactors (fusion, perhaps) use the electricity to split water into hydrogen, compress it into liquid and run gas turbines in the flying machines on that hydrogen with zero emissions

[vorticey]

why not just compressed air? diving below, is it 80 metres?, they breath helium (or a mixture) so the air doesnt explode. this would be around 90 times the attmesphere. would need a good stroke on the crank i spose:confused: or maybe it takes more energy to compress the air than the explosion makes?? :ok:

[NickLappos]

vorticey,

Just storing energy won't work, because the aircraft needs so much of it. If you squeeze air into a bottle and then let it out into an engine, you get less than you put in. If you bring some gasoline, you get a tremendous return on its weight. For example, a pound of air squeezed to 90 atmospheres has about 2.6 million ft-lbs of stored energy in it. If it were used in 1 minute, it has a total of 78 Horsepower for that minute. If a pound of gasoline were compared, it has 14 million ft-lbs of energy in it, and delivers 424 Horsepower if burned in 1 minute.

In other words, fuel is about 5 times more weight efficient when compared to stored air. And we didn't figure in the weight of a compressed bottle as compared to a fuel tank. My guess is the bottle would have to be 5 to 10 times heavier than the fuel tank, a further penalty.

You have also pointed out why electricity is so poor in flying machines. Recall that the electric motor needs to have energy delivered to it, so it needs to be fed those enoumous amounts of energy to make the power, and that energy is hard to come by.

PS they breath helium at great depth because of nitrogen narcosis, not because of explosions. At high pressure, nitrogen is an anesthetic and makes you high! Helium only makes you talk like Donald Duck.

[Benet]

Nick, I have to disagree with you here.

I wasn't able to download the PDF you linked to, but you're definitely looking in the wrong place for your electric motor. Perhaps the one you found was designed for elevator installations? The one I found here (http://www.engineering.sdsu.edu/~hev/motor.html) delivers a lot more power than your Lycoming and weighs 180lb including its cooling system so don't forget to take off the squirrel cage!

I know my batteries are going to be heavier than a fuel tank. But I'm also taking out both gearboxes, the mechanical drive shaft, the oil cooler, the clutch, the alternator, the starter motor and any other IC-related things I can think of...

I don't have the slightest intention to use fuel cells. They have a very poor energy density and the usage problems you describe. Nor would I use hydrogen - current storage methods involve a high-pressure tank storing liquid hydrogen, and the energy density of the tank + hydrogen is way below the current best offered by batteries. Chemical batteries are the closest thing to gasoline, as described at the EVWorld link in my previous post.

You're right about electricity being a 'secondary' power source; something has to burn or turn somewhere to generate the electricity. You overestimate the transmission losses, which leads you to conclude that a primary power source is more efficient than a chain which includes stored electricity. This would be true if small internal combustion engines were at all efficient. Do the math: 65% efficiency in a power station vs 10-15% efficiency in a small IC engine. There's a lot of leeway for transmission losses in my electricity chain!

Keep up the counter-arguments though...

Benet

[NickLappos]

Good data, Benet, but bad math. That 180 lb motor you found is nice, but it is only 70 HP continuous power!

Also, no power plant on the planet has more than 50% efficiency (unless they repealed Carnot's cycle), most are around 35% or so. Some experimental plant models get 40% as do fuel cells.

The total system efficiency is the product of the 35% (power plant) x the 90% transmission x the 86% of the motor for a net 27%, about the same for a good gas powered piston engine. My Honda a few years ago was 24% efficient on the highway at 60mph!

And that does not include the massive battery system, nor the 350 lbs for the motor (2 x the 70 HP motor you found).

Still a long way off, and not closing, I think. But a good fact finding debate, nonetheless!

[Dave_Jackson]

There are electric motors using rare earth magnets and brushless commentators that have a horsepower to weight ratio of one-to-one. They turn at around 60,000 rpm

Also, there is a Russian design of gear reduction that has ratios of around 250:1, with only two or three gears and low friction loss.

[NickLappos]

OK Dave, now we know. Your dreams are filled with an electric synchropter with three gears in its 60,000 rpm transmission, and a fiber optic electric cord 200 NM long!

I still see Nichole Kidman when I close my eyes!

[Dave_Jackson]

Hi Nick,

I'm sure you agree that electricity will eventually replace fossil fuels. Naturally, this will require significant improvements in the means of producing the electrical energy, storing this energy, and converting this energy to physical motion.

Some of this technology should eventually transfer from mass-produced land vehicles to air vehicles. But, probably no electric synchropter in our lifetimes.

Best that helicopter manufacturers buy the energy storage and conversion devices from outside sources. Hell, you know better than I that helicopter companies could better spend their limited R & D funding on improving the rotor ( excuse me ~ two rotors :D ).


P.S. If a dream is a type of storage device, like a battery is, would a dream about Nicole Kidman be a wet battery or a dry one?
http://www.unicopter.com/Temporary/sexy_eyes.gif

[NickLappos]

dave,
The energy technology dreams of the future all rest on "deus ex machina" of fusion reactors, sinced everything else we have tried really doesn't work very well. Actually, nucular fission does work well, but technologists get an F in public relations, so we are in the situation we are in as a result.

Once we get good cheap energy from fusion, it will be the source, and electric distribution will dominate the land side. I think liquid hydrogen gas will serve as the fuel source for transport devices in air and space, since the weight energy density is so good. Fuel cells might get very good, too, but all they would do is re-combine the hydrogen and oxygen that we had split earlier.

Regarding Nichole, she sent me this yesterday:

http://www.s-92heliport.com/nichole.jpg

[Dave_Jackson]

Nick.

You're right about public relations.

France gets 70% of its electrical energy from nuclear plants. They have (maybe no longer) weekly public tours of a shut down facility and also a separate tour an operating facility. Even foreigners could take the tour if they showed their passport.


Good picture. :ok:

[Pat Malone]

Imagine your electric R22 getting struck by lightning.
Now watch that sucker whizz across the sky.

[AdamFrisch]

I keep banging on about this in other threads for aviation in general. But it makes extra muchness of sense for helicopters. And until batteries are where they need to be, a hybrid solution is very interesting.

Let's toy with the idea for a second.

Brushless motor or motors run the main rotor and anti-torque. You have small battery that can power heli at full power for about 10 minutes. You have turbine APU that runs a brushless gen that recharges the batteries during the flight and/or can directly power the brushless motors. Look at the benefits:

1. No gearbox needed, direct drive on the shaft. Weight savings, reliability improvements.
2. Brushless motors give more power per weight than any other engine (easily about 8-10Kw/kg - beat that gas turbines), which saves weight further.
3. Anti torque is direct driven by a dedicated brushless and rpm only, no complicated shafts, no blade actuation.
4. Brushless motors are pretty much only limited by bearing life, so maintenance should become very cheap.
5. APU gen set can be made cheaper and to lesser standards and be overhauled less frequently because if it should fail, you have 10 minutes on battery power to get safely down.
6. For HEMS and other time critical operations, startup and shutdown would be a 10 second affair. Just power up and go on battery power, then start the APU when you're airborne. That time could save lives.
7. No over temps, no over-torques, no cool downs, no altitude penalties, no shock cooling, no performance losses from tail, no LTE, etc.
8. Much less noisy.
9. Training could be done on batteries alone that get swapped and recharged, which would dramatically lower the cost of training. At least at the home field.
10. Fadecs and governing becomes a piece of cake, as all brushless motors keep the rpm you tell them to keep, regardless of load. That's how you drive them electronically. It's literally a $10 circuit.

I was thrilled to hear about Sikorskys 300CB that they converted to electrics and flew before Oshkosh. It can only fly for 15 minutes at the moment at full power, but it's a great start. Battery capacity has steadily increased over the years and with the new nanowire silicon batteries in development with 10 times more capacity, it could be all over for fossil fueled aviation much quicker than we think. Mind you, I'm no environmental nut, I just welcome all the benefits of electric power. It has virtually no drawbacks and is perfectly suited for aviation.:D

But let's say one of the big manufacturers presented such a ship tomorrow, the certification processes are not in place. It's going to take FAA and EASA decades before they get on the ball, is my suspicion. That's probably going to be the funnel.

[lelebebbel]

You have small battery that can power heli at full power for about 10 minutes.
Even a R22 according to RHC needs about 60-70kW to maintain level flight at cruise speed. To deliver that for 10 minutes you need at least a 10,000Wh battery - about 200 times the capacity of a big laptop battery, or 20 car batteries. For a R22. 10 minutes.

Thats why the CB300 demonstrator can fly only for 15 minutes.

1. No gearbox needed, direct drive on the shaft. Weight savings, reliability improvements.
2. Brushless motors give more power per weight than any other engine (easily about 8-10Kw/kg - beat that gas turbines), which saves weight further.

Saves weight further? The Gen/Electric Motor/battery are replacing a gearbox, so weight is only saved if they are lighter than the GB.
The turbine is still needed.
Also, what would a brushless motor look like that can deliver, say, 200kW at 400RPM (for main rotor direct drive of a 5 seat helicopter), and would it really be light?
And imagine the battery for THAT.

4. Brushless motors are pretty much only limited by bearing life, so maintenance should become very cheap.
only the gearboxes are replaced in your example, the turbine is still there.


... no altitude penalties, no shock cooling, no performance losses from tail, no LTE, etc.
8. Much less noisy.
Why no altitude penalties? Again, the turbine is still there and required. Same with the noise.

An all electric helicopter would be a great thing for many reasons - but, given the poor energy efficiency of rotary wing flight in general, and the weight problems that come with it, I believe helicopters will be amongst the last vehicles on earth to be succesfully converted to battery power. And that will happen only after some massive breakthroughs in battery technology.

[Pandalet]

While I agree that an electrically-powered helicopter offers many advantages, and I personally think the hybrid idea is jolly exciting, it is important to remember that most electricity is generated from fossil fuels. Assuming battery technology improves massively, and we can store a useful amount of power in a usable weight, that battery still needs charging - where does that electricity come from? If it's out of the wall socket, ultimately it'll come from fossil fuels.

The other thing to bear in mind (and this is something the current crop of electric cars are running up against) is that you're probably going to need a fair amount of power to run your electric helicopter. Assuming you have somewhere to store said power onboard (whizzy batteries or whatever), you still have to get it in. The capacity of the average household outlet might get you fully charged up in a couple of days, perhaps a week or so - not exactly convenient (endurance of, say, 3 hours per week)! Assuming you have access to a properly meaty supply, and the various connectors and lines to get it to your pad, you're effectively tied to a single base (almost nobody else will have the necessary setup). The hybrid idea is nice, as the necessary infrastructure is already in place, but for fully 'leccy choppers to really take off (ha ha), you need quite a lot of infrastructure upgrade.

Sadly, as much as I'd love to see a proper helicopter based around electric motors, I think there's a bit of a chicken and egg problem here. Any suggestions as to how that can be overcome?

[maxtork]

With an electric set up as described you are basically trading a fuel tank for a battery. You can run the fuel tank to lower levels to save weight and allow the helicopter to do more work. A battery weighs the same if it is fully charged or empty so you would have the weight penalty of a full tank of fuel no matter where you go.

Max

[Tazzz]

Hello everyone
Electric seems to be full of advantages.
But I propose yet another technology.

Magnetic Motor

This video is an example of a magnetic motor of the simplest there is.

But if you have time to see one or two more videos it's better to understand the technology.

PFGiWiXMHn0

Already there are more ideas on how to maximize this energy and believe me, there's more to come.

Engineers can do anything if they want. (If they are allowed!)

If you adjust that supply power to the helicopter. we do not need more fuel or batteries.

just an idea ...





:)

[AdamFrisch]

There probably aren't any weight savings in the hybrid configuration.

But you would eliminate gearboxes and all the headaches that come with that. You would eliminate the whole anti-torque shaft, head and actuation. You could do startups in no time etc. And it would be much more reliable as electric motors pretty much never wear unless the bearing goes.

The fossil fuel debate is interesting. However, even though your electricity might be fossil fuel based (not always, but likely) it makes much more sense to ship all the fuel to a power station, than to truck it out to every nook and cranny of the world to fill it up into aircrafts. The infrastructure of electric delivery is already there, it's paid for and available pretty much everywhere. You can refuel anywhere. Obviously as electric cars are already becoming quite the reality, I'm sure there will be some kind of "refueling" standard in place for them. Perhaps aviation could use the same connectors and infrastructure?

[SilsoeSid]

The future of the helicopter is electric.

Didn't they say that about cars back in the 1900's?

[AdamFrisch]

Didn't they say that about cars back in the 1900's?

It's taken a while, but for cars it's def happening now. You just have to see how much the Prius has sold worldwide. And how every manufacturer is scrambling to get electric or hybrid cars out on the market.

Aviation might take a bit longer, but I'm personally 100% certain it will happen in my lifetime.

And Tazzz, that seems like yet another version of the elusive perpetuum mobile. It hasn't worked in the last 500 years and will never work as long as Newton is in control.

[ShyTorque]

You could do startups in no time etc.

But a turbine takes very little time to start in any case. A large percentage of start time for a twin engined EMS helicopter these days comes from waiting for the avionics to come on line, not its turbine engines.

[Plain Torque]

I reckon that most people reading this thread have already flown an electric helicopter. I actually owned my own a few years back! Okay, so it was a scale model co-axial helicopter with a little remote control but still it proves it is feasible.

I guess what is needed is a substantial amount of investment from our industry. However, considering a hell of a lot of helicopters are sold to service the oil industry to extract fossil fuels I'm doubtful that helicopter companies will be pouring money into R&D!

As an aside lets hope electric helicopters don't fly into walls like mine seemed to have a habit of doing!!

PT

[Hunt3r]

I'm pretty sure that making an electrically driven helicopter with a turbine would make a lot of sense, seeing as how it's a lot more reliable and definitely less finicky then a gearbox. Lithium based batteries that can get the APU online to get the main turbines online, that would power rotors via electrical power has sort of been done before, and proposed for vehicles like tanks, that also have a lot of weight spent on the drivetrain.

[iorgasilviubogdan]

I'm not so sure that separating the tail rotor from the main rotor is such a good idea.
What if something happens to one of the engines?

[krypton_john]

Sorry Adam, but IMO this is nonsense.

All the energy in this system is initially coming from the APU to charge the battery, so you may as well drive the rotors from the APU and save the battery and electric motor weight.

But it is much worse than that. There are significant energy losses in the electric generator and then the electric motor, so the fuel efficiency overall is much worse than a plain ol' turbine.

When batteries are good enough for a one hour flight, and they are ground charged from a non polluting electric power source such as solar, hydro or nuclear, then it all becomes worthwhile.

As for the Prius - it's a gimmick. You will get better overall efficiency in the *real world* out of a small modern turbo-diesel.

[SilsoeSid]

Didn't they say that about cars back in the 1900's?
It's taken a while, but for cars it's def happening now. You just have to see how much the Prius has sold worldwide. And how every manufacturer is scrambling to get electric or hybrid cars out on the market.

Aviation might take a bit longer, but I'm personally 100% certain it will happen in my lifetime.


As that 'taken a while' has been about about 100 years, I'll wager a fiver on that last sentence ;)

[AdamFrisch]

All the energy in this system is initially coming from the APU to charge the battery, so you may as well drive the rotors from the APU and save the battery and electric motor weight.

The idea was to charge the battery from the ground and have to APU just keep it topped up. Only in a remote area where no electricity could be found, would the APU be running to charge the battery up.

Pretty much like the Chevy Volt that comes out now.

But it is much worse than that. There are significant energy losses in the electric generator and then the electric motor, so the fuel efficiency overall is much worse than a plain ol' turbine.

Yes, there are energy losses, but so are there in gearboxes. I have a hunch the APU and Gen will weigh less than a gearbox, but I could be wrong.

As for the Prius - it's a gimmick. You will get better overall efficiency in the *real world* out of a small modern turbo-diesel.

This is true. However, may I make a direct comparison to the field I work in - Cinematography.

All these new HD cameras and digital stills cameras have come along and pretty much put film still cameras out of business. Most of you probably have an old film camera laying around in your house, but you shoot on your digital cameras these days. Film cameras for the motion picture industry is still hanging on, but their days are numbered. Now, do any of these HD or still cameras resolve more pixels than film or actually look better? No they don't. In fact, the latest HD cameras have far less resolution than film has. I can easily extract 6K information from a 35mm film frame, whereas an HD camera barely manages 2K, and that's heavily compressed. Yet they've completely taken over. Why? Because it's good enough and convenient.

Now, would you rather not have a little bit less range in your helicopter, if you could virtually eliminate TBO's on drive components? If you could tenfold reliability? If you could fly for half the cost? I think most business and individuals would be happy to make that trade. And that's where I think electric cars, aircraft, whatever will live in the beginning. It's an interesting future, for sure.

[Hell Man]

The future of the helicopter is electric.


Hmm ... I don't think so! :ok:

[ShyTorque]

Now, would you rather not have a little bit less range in your helicopter, if you could virtually eliminate TBO's on drive components?

No!

Pilot:

"Sorry Boss, we can't get to the destination for your important business meeting....battery's run flat. That's it for today. I'll get you a taxi and I'll try to get the aircraft recharged overnight. I'll come back for you tomorrow and do the same again... Look on the bright side, we have more TBO on the drive components!"

Boss: "You're fired!"

Adam, helicopters need more range and endurance, not less!!

[heliski22]

Adam, helicopters need more range and endurance, not less!!

Got it in one!! :ok:

[TwoStep]

What about a hybrid? Electric-powered tail rotors, but the main rotors will continue to be driven by the turbine? No more complex drive shaft, more power to the main rotors, reduction in weight etc...

[chopjock]

Pilot:

"Sorry Boss, we can't get to the destination for your important business meeting....battery's run flat. That's it for today. I'll get you a taxi and I'll try to get the aircraft recharged overnight. I'll come back for you tomorrow and do the same again... Look on the bright side, we have more TBO on the drive components!"

Boss: "You're fired!"
Or alternatively...
"Sorry Boss, we can't get to the destination for your important business meeting... Aircraft in for maintenance again. That's it for this week or two.
I'll get you a taxi and I'll try to get another aircraft hired in. Then in another 50 hrs we do it all again".

Boss: : "We're stuffed"

[ShyTorque]

That's it for this week or two. I'll get you a taxi and I'll try to get another aircraft hired in. Then in another 50 hrs we do it all again".

A week or two for a 50 hour? :eek: Find another aircraft type, or another maintenance organisation!

[ShyTorque]

What about a hybrid?

Hybrid chickens = Good.

Hybrid helicopters = No thanks.

[lelebebbel]

What about a hybrid? Electric-powered tail rotors, but the main rotors will continue to be driven by the turbine? No more complex drive shaft, more power to the main rotors, reduction in weight etc...

1) How is a high power generator, remote electric motor (heavy!), power regulation system (probably including huge buffer capacitors to deal with sudden load changes) less complex OR lighter than a driveshaft and a 90deg gearbox?

2) Why would such a system provide more power to the main rotor?
The electric tail rotor still needs the same power as a normal one. The method of getting it there would be way less efficient than with a simple driveshaft.
So, less power available to the MR, and more weight.

[Soave_Pilot]

A breaktrough where one could develop a generator or alternator capable of recharging the bats while you are airborne.:ok::ok:

that would be the mystery solver :E

[Soave_Pilot]

and we only have 50 more years left of oil in the world... so we need to come up w/ something fast!:eek:

[AdamFrisch]

1) How is a high power generator, remote electric motor (heavy!), power regulation system (probably including huge buffer capacitors to deal with sudden load changes) less complex OR lighter than a driveshaft and a 90deg gearbox?


Unless you've been an R/C flyer in the last 10 years and seen the revolution there, I don't think everyone here understands just how light and efficient modern brushless motors are.

I can buy and off the shelf 20hp brushless motor that weighs 2,5kg (5lbs)!

Hacker A200-6 Motor - HAA2006 (http://www.espritmodel.com/index.asp?PageAction=VIEWPROD&ProdID=7692)

With even more exotic materials in the housing, that could probably be made even lighter. No drive shaft, tail rotor assembly or linkage is ever going to be lighter than that.

Just as a thought experiment: an R22 probably needs, what, 10-15% of the power to power the tail rotor in its most extreme condition? That's roughly just about 20hp. So this itty bitty brushless would be able to that job. Cost less, vibrate less, weigh less and be more reliable.

And since they are so light, you can overpower the tail rotor. Let's say you stick a 30hp motor in the example above - much more than what's needed in normal conditions. This will give you an extra margin of safety and maybe avoid a LTE situation. It's there if you need it. Unless the battery is flat, that is;)

[Hell Man]

With only have 50 more years left of oil in the world ... we need to come up with something fast!

Says who?

Oil reserves are plentiful, says Aramco chief | IBTimes (http://uk.ibtimes.com/articles/42230/20100810/petroleum-oil-energy-reserves-peak-oil-aramco-reserves-oil-futures.htm)

Just another fallacy like global warming!

Did you know that there are billions of barrels still completely untapped here in the US, Canada, Russia, Indonesia and Africa!

Nice day man!

HM

[lelebebbel]

I own a model helicopter with a Brushless motor, and I still don't believe it.

That motor only replaces the TR gearbox. The TR gearbox of an R22 is pretty light, i doubt it weighs more than 2kg.
You still need the power regulator, cables, and mainly - a 15kW generator and some decent size buffer batteries.
Not to mention that the motor, like all brushless motors of comparable size/performance i have heard of, runs at high RPM. So you would still need a 3:1 reduction GB.

The TR thrust in helos is limited through the pitch angle of the blades to protect the drivetrain, the TR itself and the tailboom. If one wanted a stronger tailrotor, these components need to be made stronger. That problem doesnt change with an electric one, except you'd need to beef up the motor and generator instead of the drivetrain.

10-15% of the power to power the tail rotor in its most extreme condition?
A lot of books say up to 30%. I don't know though.

I think lot of RC flyers see the amazing performance they can get out of electric RC helos, and underestimate the problem of scalability.

[Soave_Pilot]

Says who?

Oil reserves are plentiful, says Aramco chief | IBTimes (http://uk.ibtimes.com/articles/42230/20100810/petroleum-oil-energy-reserves-peak-oil-aramco-reserves-oil-futures.htm)

Just another fallacy like global warming!

Did you know that there are billions of barrels still completely untapped here in the US, Canada, Russia, Indonesia and Africa!




YEAH! Right!

You are gonna believe in some rich saudi bizz man with his legs tied to oil companies stocks that just writes an article out of nowhere...:ok:

And you think the Americans will let the ''untapped'' oil be tapped after what just happened in the gulf? := Don't think so.

And don't forget about China, India and Brazil were they are booming and starving for more and more oil after each year.

[Dave_Jackson]

The future of electric power in VTOL craft is more than the simple replacement of a gas engine with an electric motor.

It is about the ability to provide unique enhancements, which today's reciprocating and turbine drives cannot provide.


Dave

[Deemar]

Another issue with this proposal is that you would get lag in your anti-torque control. Direct drive tail rotors work on small model helicopters because the tail rotor has so little inertia it can change speed really quickly and you don't get any control lag. On an R22 sized helicopter, I imagine there would be a noticable lag and on a significantly larger helicopter, I can imagine it would be difficult to control.

Another issue is that with vibration and fatigue. One of the reasons that helicopters are designed with a specific main rotor and tail rotor RPM is that it makes it a lot easier to do the vibration analysis and ensure the helicopter doesn't have any nasty resonances at the operating RRPM.

[chopjock]

Deemar
Direct drive tail rotors work on small model helicopters because the tail rotor has so little inertia it can change speed really quickly and you don't get any control lag.The speed does not change. The electric tail rotor would be at a constant rpm with collective pitch.

[Dave_Jackson]

cattletruck, you're right. It may be a race to see if effective electrical storage or a cure for cancer comes first.


Regarding an all-electric tail rotor, The current project involves the application of a torque-pitch coupling to a pair of small electrically driven main-rotors ~ Electrotor - SloMo (http://www.unicopter.com/ElectrotorSloMo.html). This feature should be applicable to a tail-rotor, also.

When the pilot increases the power to a rotor the torque reacts before the speed does. This increase in torque causes the collective pitch to automatically increase, then as the speed increases the torque and the collective pitch partially reduce.

Dave

[22clipper]

Interesting debate lads. While its true that some breakthrough in battery technology is needed to get anywhere range wise with a purist all electric chopper today, the technology is improving at 9% per year which means that batteries will be half the size for the same energy storage in just a decade even without a game changer.
Re hybrids. The auto industry have tweaked that's it's easier to move energy over wires than drive shafts, the Lexus RX400h has an all electric rear transaxle for example. A turbine (or two) running a poly phase alternator with wires to all electric MRB/TRB direct drives with minimal or no batteries is not science fiction as a concept.

[blackhand]

The future of the helicopter is electric, limited only by the length of the power cord:cool:

[Squeaks]

When the pilot increases the power to a rotor the torque reacts before the speed does. This increase in torque causes the collective pitch to automatically increase, then as the speed increases the torque and the collective pitch partially reduce.

Dave,

I think you should revisit that explanation :hmm:

So the collective pitch automatically increases as a result of increased torque: what sort of helicopter are you talking about?

[chopjock]

Squeaks

So the collective pitch automatically increases as a result of increased torque: what sort of helicopter are you talking about?

A governed, gyro stabilized electric (fly by wire) tail rotor would do just that.

[chopjock]

An electric tail rotor should be safer too. For example you could have the ability to switch it off in flight if for example you had a "jammed pedal"
In fact why don't they do that now, without waiting for the all electric helicopter to come along?

[killawarra]

iNeshiY4ixI

Havent really had time to look every little thing up but first impression.. Very cool. We are lucky we have these stubborn scientists and engineers.

Im gonna look this stuff up a bit closer but its looks promising indeed..

[Dave_Jackson]

I think you should revisit that explanation

So the collective pitch automatically increases as a result of increased torque: what sort of helicopter are you talking about?

Squeaks,

The specific Torque-Pitch Coupling does not exist in current helicopters. It is an innovation that is intended to simplify the pilot's control of very light recreational helicopters. The micro-light Electrotor project is an ideal testbed for implementing and playing with this idea; due to its low cost, the incorporation of other ideas, and the ability to initially fly it as a large R/C helicopter.


This is a revisit to the explanation, but it is a long and boring one. http://www.unicopter.com/Wink.gif
DESIGN: Electrotor-SloMo - Control - Flight - Auto-Collective by Torque-Pitch Coupling - Overview (http://www.unicopter.com/1893.html)
OTHER: Rotor Concept - Flight Control - Torque/Pitch Collective Rotor Hub (http://www.unicopter.com/0575.html)


Dave

[Dave_Jackson]

.
The World’s first manned flight of a 100% electric powered helicopter was conducted on the 12th of August 2011, after 2 weeks of tethered flight tests. This machine, designed and test flown by Pascal Chretien, for the French based company Solution F, is the outcome of a remarkably short development period that was initiated in August 2010.

This ultra light coaxial helicopter weighs 170-Kg empty, including 60 Kg of high performance air-cooled Li-ion polymer batteries that can deliver 43 KW continuous, and 52 KW peak. The craft weighs 247-Kg at takeoff and offers 10 to 12 minutes flight time. To save weight, conventional cyclic and flight controls were replaced by a weight shifting system, as well as a specific design for rotor inertia, and blade pitch. Collective and yaw are achieved via electrical flight controls.

An advanced MOSFET based feather light drive train offers astounding 87.5% end to end efficiency, from batteries terminals to rotor mast.

This helicopter is a demonstrator intended to pave the way for hybrid rotary wing aircraft and is a test bed for new technologies. Flight envelope expansion is ongoing.

.
http://www.electrotor.com/Temporary/Hover IGE 1 Small.jpg

http://www.electrotor.com/Temporary/Hover IGE 2 Small.jpg

http://www.electrotor.com/Temporary/Hover tethered 1 Small.jpg

.
Dave

[Lindsay55]

Dont know that I'd want to be sitting on 60kg of Li-Po batteries!
Lipo (Lithium Polymer) Battery Fire through mechanical Damag - YouTube

[Rigga]

Hmmm... I wonder if that's why they put it into a ventillated protective box?

[ReverseFlight]

This machine has a really cyber look except for the rear stabiliser which looks a bit like a 5th century Chinese emperor's fan !

[Dave_Jackson]

Yes. The lithium-ion batteries are one of the risks that exist in the development of this new type of helicopter.

The batteries have a combination of conduction and convection based cooling.

The large movable rudder is an addition to minimize cross-couplings, as the project develops. Pascal has joked that he should have made it out of bamboo.


Dave

[Graviman]

Great! Thanks for posting this, Dave. Looks a lot safer than putting a match to AvGas - you check all your fuses right? ;)

Interestingly there is no real performance disadvantage, in terms of power to weight, with LiPo over internal combustion. Hybrids using LiPo & fuel cells seem to be hitting the mark in fixed wing aviation. There are already some other fixed wing projects going "commercial" with fuel cells now that the concept has been demonstrated by Boeing/Diamond/Intelligent Energy:

ENFICA-FC - ENvironmentally Friendly Inter City Aircraft powered by Fuel Cells (http://www.enfica-fc.polito.it/)

Actually, there may be some serious benefits to electric power in helicopter pilot training. If all you need to do is hover around the airfield, along with a couple of circuits, then this may be a much more cost effective approach. No more TBO to drive costs up and no more expensive development into ancilliaries like cooling and govenor control. The powertrain can be relatively simple with minimal vibration mounting, ideally with rotor system optimised for hover efficiency over cruise efficiency. Just make sure there are a couple of power packs on standby near the hanger, even recharge time is no longer a big headache.

[Dave_Jackson]

Hi Mart,

The feat was released on Gizmag last night. It gives more information on his craft and the initial flights.

Modern-day aviation pioneer achieves world's first untethered, manned electric helicopter flight. (http://www.gizmag.com/first-successful-manned-electric-helicopter-flight/19716/)


He has much more work to do, but it is the start of manned electric rotorcraft.

Dave

[aviate1138]

How long to recharge? Li-Po batteries are not fuel cells are they?……..and all because of the myth of global warming/climate change…...

[Graviman]

The distinction between various electric powertrain technologies is becoming more blurred as performance improves. A fuel cell uses some kind of hydrocarbon fuel, with hydrogen favoured for transport applications but heavy oils possible for static applications (steam reformation used to break down into H2 and CO2). Lithium-Polymer batteries are the latest generation of energy storage device but are capable of extremely high rates of charge and discharge. Often the two technologies are combined to allow fuel cells to trickle charge LiPo batts in between demand peaks. For constant high power applications like helicopters this approach is of limited use, but LiPo will eventually give way to true high power to weight fuel cells. When will this happen? Eventually...

[Dave_Jackson]

Pascal has asked that this link be posted on PPRuNe. It provides more information on his craft, and a respect for the support he received.

First manned electric helicopter flies (http://www.lithiumbalance.com/index.php?option=com_content&view=article&id=136%3Afirst-manned-electric-helicopter-flies&catid=8%3Anewsfeed&Itemid=163&lang=en)


Dave

[Graviman]

Looking at the photos, it's interesting to note that there is no collective pitch mechanism or sprag clutch in the drivetrain - that would worry me. This will likely be the main area of development before getting out of ground effect. Interesting to see if a conventional swash plate, with cyclic mechanism, makes it into the design too. Power reserve would also allow higher inertia rotors, which will help desensitise control for improved dynamic stability, as well as extra margin for when the batteries run flat.

That yaw setup with a potentiometer on each pedal controlling motor rpm is interesting, although I can't imagine rpm controlled collective to be easy. If collective mechanisms are fitted then differential collective yaw control will likely be fitted, but this will lead to force control rather than velocity control. If all of the control headaches like reduced yaw authority in autorotation are to be avoided it would be a pity if some kind of differential velocity yaw system was not kept. As long as motors are reliable then they may as well stay there, even if put through a geared differential. Even in autorotation the motors will quite happily transfer power from one rotor to the other.

That landing gear is subtle but clever, if I see it right. The skid struts point to the centre of mass, while being suported from below by tensioning bungees. This allows for some landing energy adsorption, and will not try to topple the machine if a skid touches down in sideways flight. Instead the offending skid will fold under the machine pushing upward through the CG.

In summary: Some initial oversights with some clever features

In conclusion: Congratulations Pascal! :ok:

[Lonewolf_50]

Graviman:
Often the two technologies are combined to allow fuel cells to trickle charge LiPo batts in between demand peaks. For constant high power applications like helicopters this approach is of limited use, but LiPo will eventually give way to true high power to weight fuel cells. When will this happen? Eventually...
When will fusion reactors be used to generate electricity? For the last fifty years, it's been about fifteen years away from application, hasn't it? :p

As to power for a electric helicopter ... the latest article on graphene layers used to manufacture batteries looks promising.

Apparently, something like a 4:1 power stored to weight improvement over current best.
They say the introduction is around five years away ... but we shall see.

In re this prototype: you have a pure electrical power suppply, and your flight control commands are transmitted via electrical circuits.

Does anyone besides me see a problem with this? There is a non trivial problem with this when you get out of the laboratory.

[SASless]

Helicopters are far less efficient than cars....just how successful have "electric" cars been?:ugh:

The only way to make a helicopter "green" is by means of paint!:E

[500e]

"The only way to make a helicopter "green" is by means of paint!http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gif"
Like the thought:ok:
Pure electric cars are not cost effective at present, even with the UK govs bribe.
20+K for a car & that's with the bribe deducted.
How long is the life of battery pack? & at what cost, some manufacturers will not sell battery only rent, so you have a car with limited range, no instant re fill of power source, mostly small hatch models, say "Smart car" deduct battery price from purchase, average ownership of new car 3 years, 2nd owner budgets for new battery 1\4 1\3 price of new car Standard Smart say 10K electric Smart say 19K+ do the sums, then we get to a E Heli don't think viable comes into it for some time, nice idea shame about the prices.
An 80% uplift on a 300:{
A resume of Ecars
Electric Vehicle Costs UK | Electric Car Costs 2011 | Next Green Car (http://www.nextgreencar.com/electric-cars/car-costs.php)

[hillberg]

Electric helicopters? Kaman 1950s had it , Nothing new other than "Batterys" Like i want to be fried by a bat pac, sorry it has a lot more to go for power density. Political Correct tech= Smokin Dope

[Praetor]

I'm a new pilot and certainly no expert on electromagnetic motors, but I had an idea that I wanted to get outside views on feasibility- probably low but worth discussing, I suppose...

What about an eletric motor-powered shaft assisted by electromagnets down the length of the shaft that assist in "pushing" the shaft...this would require a rotor mast with magnets down a certain length of the shaft to be pushed, so the weight added may nix this idea from the get-go, but if not, it seems like the electromagnets around the shaft could be adjusted to "squeeze" or release the shaft in order to adjust RPM assistance. Would it not also be possible to use the rotation of the rotor shaft to charge the batteries?? Again, not an expert on this by any means and I've heard the whole self-sustaining motor has been debunked, but it's a fascinating idea. Any thoughts?

[Dave_Jackson]

Rraetor,

If '"pushing" the shaft' implies rotating a shaft that is common to, or concentric with, the aero-rotor and the motor; then it is a viable idea. In fact, this idea has previously been done, displayed and discussed on numerous occasions, this forum being one of them.

Sikorsky liked it so much that they are still attempting to patent the pre-existing idea; (http://www.pprune.org/rotorheads/379308-sikorsky-attempting-inhibit-others-developing-electric-rotorcraft.html) to exclusion of all others.


The idea of using the airflow through the rotor to charge the batteries was also discussed on PPRuNe, on this thread (http://www.pprune.org/rotorheads/229063-buy-not-buy-question.html).


Brilliant ideas, if I may be permitted to say so.

http://www.unicopter.com/Anonymous.gif
Anonymous

[Praetor]

Oh, awesome- I had no idea! Encouraging to know they're not simply pie-in-the-sky notions of my own :8

[riff_raff]

A better title for this thread probably would have been "The future of the light helicopter is not turboshaft".

I doubt we'll see battery technology advance enough in the next 20 years to make a pure electric helo drivetrain a commercial reality. But that doesn't mean we won't see some progress with various hybrid drivetrains.

For example, how about a set of variable frequency free-piston engines with linear generators (http://nextbigfuture.com/2008/09/free-piston-engine-could-be-twice-as.html), that cycle on/off based on demand. These engines are very lightweight and can operate at high cycle pressures, giving extremely high thermal efficiency. Their overall BSFC rate would easily be half that of a small turboshaft engine. And if you don't like electric drivetrains, how about free-piston engines and a hydraulic drivetrain? Or if you want to be carbon-free, how about a free-piston engine that operates on ammonia fuel?

To determine what approach might be best, one needs to objectively evaluate the entire rotorcraft drivetrain's particular requirements, including cost , weight, efficiency, reliability, etc. Simply taking the position that "electric is green, therefore it's the obvious choice for future rotorcraft drivetrains" is a bit closed-minded.

[hillberg]

You will find a paperless bathroom before you get a useable elcectric helicopters with any range & payload.

[HueyDog]

hillberg, I take it you have never been based in the Middle East or Asia?

[hillberg]

That a good one-Been to China, They have toilet paper in beijing. Never seen the middle east, Could plug that bug in a camels behind.

[topendtorque]

A little off beat is the story below perhaps, but in the 'rhythm' of things electrical and the fact that emeritus helicopter engineer Charles Kaman is quoted for the use of a clever little gizmo that we all take for granted whenever we use a strobex.
Either that or its a story that only a rock an roll guitar player could come up with?

Maybe the elctrical rotary machine could carry enough of these gizmos around to be self sustaining in current as long as heaps of vibrations were built into the invented helicopter contrivance ?

http://www.abc.net.au/catalyst/stories/3318871.htm (http://www.abc.net.au/catalyst/stories/3318871.htm)

[onetrack]

The future of electric helicopters and other electric-powered transportation devices lies in super-capacitors or ultracapacitors. These devices have the potential to utterly revolutionise electric power as a power source that can compete with fossil fuels.
However, the breakthrough technology is still just an arm's reach away... but it's not impossible, and it's not alchemy.

Australia's CSIRO was in the forefront of super-capacitor development in the early 2000's, but has gone quiet on it, in recent times. I suspect that it's all due to substantially higher amounts of research money needed, than the Australian Govt is prepared to commit.

The other angle is that this Holy Grail is encouraging companies such as the Texas-based EEstor, who are supposedly producing breakthrough ultracapacitors, but who are essentially making claims they cannot support with actual commercial products.

The breakthrough is supposedly in the relatively-newly-discovered ultracapacitor insulation material, barium titanate. However, converting excellent lab test results involving barium titanate into commercial products seem to be eluding EEstor... who still claim, however, to have an outstanding commercial breakthrough.

Until the day comes when that "outstanding commercial breakthrough" with ultracapacitors happens... and can be displayed as a commercial, sustainable result... companies such as EEstor will continue to generate excitement (and continue to bleed investors), without producing anything that can be considered a major breakthrough.

I have no doubt that that day will come, and it's not far off. However, it will take more money than EEstor has, or is currently allocating to research (knowing full well that companies such as EEstor are happy to rate directors substantial entitlements, and luxury company vehicles, as higher priorities than actual research expenditure).

Supercapacitor "battery" could lead to instant charging, long charge life (http://arstechnica.com/science/news/2007/09/supercapacitor-battery-could-lead-to-instant-charging-long-charge-life.ars)

[ross_M]

Why do battery packs have to be a part of the hybrid idea? Locomotives, earthmovers, ships etc. have long operated in a diesel-electric mode. i.e. a generator followed by a motor. Their Horsepower requirements are high too but nobody passes all that power through a battery pack.

Of course, there will be batteries but for ancillaries. You don't need to size batteries for full operating power.

[Dave_Jackson]

ross_M

The advantages of combining a limited amount of electrical storage (battery or capacitor etc) with the hybrid source are;

1/ The power from the electrical storage device is combined with that from the 'generator' for short duration - high power requirements, such as during a takeoff.

2/ Should there be a failure of the generator power source, the storage device will provide a short duration safety, such as during a landing.


Dave

[AdamFrisch]

Great stuff.

Well, the battery technology and the electric propulsion technology has advanced so much in the last 20 years that it's incredible, so it's not beyond the realms that in another 20 years we'll see workable technology. Compare that to the combustion engines who virtually have stood still since the 30's. At least in aviation. I just sent my magneto off for overhaul again and that damn thing has not changed since the 30's, lemme tell ya...

Once again, I can only compare to the automotive industry and how lightning fast things have been going there recently in regards to electrics. Tesla's Model S is imminent for release, will cost $50K and have 300 mile range. Now that's going to be very competitive. Numerous other makers have similar offerings in the works. Just look at the recent Frankfurt Auto Show - every major car manufacturer has some kind of electric or hybrid thing going on, even Ferrari!

http://www.thetorquereport.com/tesla_model_s.jpg

Tesla Model S

I don't think we'll be driving combustion engined cars in 20 years. In fact, if I ever buy a new car again it's going to be some kind of hybrid or electric thing. Not because they make more sense financially, but because it drives me nuts that my whole car is rattling, making heat, noise, emissions and burning fuel at a stop light... An all electric helicopter might take a bit longer, but I wouldn't discard some kind of hybrid by then.

[Lonewolf_50]

Compare that to the combustion engines who virtually have stood still since the 30's.
Not quite stood still.

Point first.
Electronic fuel controls which adjust for temp and atmospheric pressure, and injector ports and tune fuel/air mixture fine precision. (Granted, diesel engines continue to hold their own, but you cannot simply write off emissions.)

Point second: use of new alloys in engine blocks and other components, improve HP to weight. Good for cars, good for planes.

Won't proceed farther. The reliability of IC engines currently produced dwarfs reliability of even a generation ago. MTBF lower. (I specifically refer to cars here, suspect aircraft IC engines similarly improved)

[Dave_Jackson]

Lonewolf_50,

Your points are good from a overall perspective.

AdamFrisch references the aviation industry. To my knowledge, Lycoming and Continental have not improved their engines over the decades, and their reason is that the volume of engines manufactured for aircraft will not justify the high developmental costs.

Dave

[Lonewolf_50]

Thanks, Dave, I see the point in a different light now. :ok:

[victor papa]

Received a reference today of Eurocopter flying a AS350 hybrid yesterday. Anybody? What about Sikorsky's patent? The article says it is a backup incase of engine failure it seems to assist and ease auto rotation?

[Dave_Jackson]

victor papa,

Pascal Chretien, who flew the first electric helicopter a couple of months ago, is also moving his interest toward hybrid propulsion for helicopters.


Sikorsky's patent application for ELECTRIC POWERED ROTARY-WING AIRCRAFT, which is covered on the PPRuNe thread Is Sikorsky Attempting to Inhibit Others from Developing Electric Rotorcraft? (http://www.pprune.org/rotorheads/379308-sikorsky-attempting-inhibit-others-developing-electric-rotorcraft.html), is before the Board of Appeals.

Hopefully, the US Patent Office will continue to decline Sikorsky's intent to patent that which already exists.


Dave

[riff_raff]

victor pappy-

Eurocopter targets safety boost with hybrid helicopter (http://www.flightglobal.com/news/articles/eurocopter-targets-safety-boost-with-hybrid-helicopter-362886/)

According to the article the electric motor and lithium ion battery pack are in the cabin area on the demonstrator.

Eurocopter has successfully tested a new safety feature on an AS350 helicopter that combines a regular turboshaft powerplant with an electric motor that will provide power to the rotors in the event of a main engine failure, enabling a safer autorotation landing.

The demonstrator helicopter is a production version of Eurocopter's light single-engine AS350, which has been equipped with a supplementary electric motor.

In the event of an engine failure, the electric motor provides power to the rotor, allowing the pilot greater control of the aircraft during descent.

The airframer is now studying how to bring the concept to maturity and implement it on its production aircraft.

"Eurocopter's research and development efforts are used every day to push the frontiers by increasing helicopter safety and performance for the benefit of our customers, and we are proud to have brought the first helicopter equipped with an internal combustion engine and electric propulsion system to flight," said Lutz Bertling, Eurocopter president and chief executive.

Hybrid power has the potential to cut fuel consumption in the future, he said.

The AS350 hybrid demonstrator has its electric motor and lithium ion polymer battery installed in the centre area of the helicopter.

[NonSAC]

Re. Impact on Eurocopter

Like so many things, it "depends".

Patent protection is country specific, so inventors seeking protection beyond the borders of a single country sometimes file couterpart applications multiple countries.

With respect to the patent application that Dave has taken issue with, Sikorsky filed counterpart applications with the same disclosure and similar claims in several countries - including the European Patent Office (EPO). Were Sikorsky's EPO application to mature into a European patent, Eurocopter would be excluded from practicing the invention defined in the claims that EPO saw fit to allow - thereby potentially hindering Eurocopter's ability to develop the concept along the avenue that Sikorsky claims.

The EPO is relatively liberal in terms of prosecution being a public affair. Once published, the public can monitor events by viewing copies of correspondence between the EPO and the applicant through the EPO Register. One can even set up an automatic emailer free of charge to receive automatic email notifications when either an applicant or the EPO exchange correspondence (Register Alert). The EPO also allows third parties to submit art in an application (Third-Party Observations). And the EPO also has a relatively robust opposition process available to the public once a European patent grants (opposition period).

Sikorsky's European counterpart application is EP08861121. In November 2010 the EPO notified Sikorsky that the "application is deemed to be withdrawn" because "no use has been made of any of the legal remedies available". It appears from the information available on the Register that Sikorsky declined (or neglected) to pay the fees due to keep the application pending - so the EPO ceased prosecuting the application.

That being the case, Sikorsky presently has no right to exclude Eurocopter from practicing the claimed subject matter of the application. However, the EPO is also fairly liberal about obtaining fees from applicants - so it may be possible that Sikorsky can 'revive' the application and continue prosecution by coughing up an onerous surcharge. Consequently, Eurocopter must contend with the risk that Sikorsky might obtain some right in the future. Moreover, any product they ultimately developed might be locked out of markets where other counterpart applications issue - such as the US.

If Eurocopter is truly interested in Sikorsky's concept, it must weigh the risk that Sikorsky ultimately obtains patent protection with claims of meaningful scope in Europe or a market into which Eurocopter would otherwise sell an infringing product against Eurocopter's benefit in more fully developing the concept.

I have no idea where Eurocopter's internal calculus stands on the risk/reward balancing question. Folks with direct ties to the industry could speculate more effectively on the technical and market worth than I.

On a side note, the Written Opinion in the PCT application (PCT/US2008/076962) is worth a read. The Korean Patent Office, who prepared the search/opinion, is of the opinion that the difference between Sikorsky's broadest claim and "a radio-controlled flying toy with a rotor assembly" lies merely in the minor difference between the fields of endeavor, i.e. building toys versus building helicopters - and therefore lackis inventive step.

I guess Koreans are unimpressed by the "size matters" argument.

Cheers!
- NonSAC

[Dave_Jackson]

Franz Schoeffmann is the builder and pilot of this engine driven backpack helicopter (http://www.unicopter.com/1764.html#Schoeffman).

He mentioned that he has just about completed an electric backpack helicopter. He has been hopping with it on one motor, while waiting for delivery of the second motor.

He said that it should be on You Tube in a few days.


Dave


P.S.
NonSAC,

Thank you for the continuing updates on Sikorsky's style of 'Innovation'.

D

[Dave_Jackson]

.

http://www.unicopter.com/NoNo.gif

Guinness World Record (http://www.guinnessworldrecords.com/records-9000/first-electric-helicopters/)


Strange. Apparently, the names of those who post comments are given. But, the name of the person who is stating 'a record of fact' is not given.


Dave


Hi Senior Pilot.

[lucianpilot]

I think we should look at an alternative fuel ie. hydrogen or even using urea ( electrifying it and extracting the hydrogen, pure water emissions)
but definitely not re-invent the wheel the turbines work great, just make them more efficient, and recycle the heat for creature comforts

my little opinion:rolleyes:

By the way great work RotorHeads!
(rotor wann:ok:abe)

[riff_raff]

lucianpilot,

I don't think jet fuel will be replaced anytime soon. But that's not to say we won't see practical electric drivetrains in rotorcraft in the near future. I've seen some developments in turbine electric drivetrains that were very impressive. The technology appeared to be competitive in terms of both cost and weight with conventional drivetrains, and possibly having better efficiency and reliability. It also appeared that it would scale up quite well to any current rotorcraft power requirement. I can't really tell you anything more specific about it, but I'm sure you'll see it flying somewhere in the next 2 or 3 years.

riff_raff

[slowrotor]

Worlds first manned electric multi-copter:

e-volo - Home (http://www.e-volo.com/Home.html)

L75ESD9PBOw

[Dave_Jackson]

Hi slowrotor,

Could this be the type of slow and reliable craft that you've been looking for? http://www.unicopter.com/Wink.gif


Dave

[slowrotor]

It's getting close Dave.
I would attach these motors to my ultralight airplane. So it would only need the electric lift for less than a minute , to make it VTOL.

The cost of batteries keeps coming down.
Joby is working on an electric VTOL sailplane. Have you seen that?
slowrotor

[Dave_Jackson]

slowrotor,

Thanks. That Joby tilt-wing (http://www.jobyaviation.com/home.php) is an interesting concept. Particularly attractive is the ability of motors to be run at higher then rated capacity for a short period of time.


Dave

[muffin]

I want one of these - at least it would not suffer from mast bumping

German multicopter makes first manned flight. | sUAS News (http://www.suasnews.com/2011/11/9691/german-multicopter-makes-first-manned-flight/)

[krypton_john]

Yikes. Looks like a guaranteed, gruesome death for someone.

[ShyTorque]

In their own words the team from e-volo have the following to say.

In my own words, the team from E-Shytorque have the following to say:

"Sorry, I'm not that desperate to fly :ooh: "

[muffin]

Sorry, I'm not that desperate to fly

I bet the running cost is lower than your normal mount.

[ShyTorque]

Yes but how much for one that will do 155-160 kts and carry six passengers?

[Lonewolf_50]

Sitting in between all them rotating knives brings to mind a Monty Python sketch about Freemasons, architects, and a competition to build the next block of apartment flats ... as submitted by someone who usually builds abattoirs.

Monty Python- Architect Sketch - YouTube

[500e]

Not quite a helicopter
World's first manned flight with an electric multicopter - YouTube

[Dave_Jackson]

There is a 5-page article on Pascal Chretien's electric helicopter in the March-April 2012 issue of the American Helicopter Society's magazine Vertiflite.

On the cover it says 'The First Electric Helicopter'. The article is entitled 'The Quest for the World's First Electric Manned Helicopter Flight'.

The article is impressive and Pascal should be proud, considering the long hours and work that he put into the project.


Dave

[Ian Corrigible]

"You want me to track & balance what?"

http://i.imgur.com/fbMPxA8.jpg

http://i.imgur.com/fVF89pP.jpg

(Source (http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:a68cb417-3364-4fbf-a9dd-4feda680ec9c&plckPostId=Blog:a68cb417-3364-4fbf-a9dd-4feda680ec9cPost:ee5d4cec-2142-4a5b-bc61-38faa193bff9))

I/C

[Dave_Jackson]

Ian,

OK, two rotors can do.

But make that little wee one bigger, and make it point upwards where it can do some work.

Dave

[riff_raff]

OK, two rotors can do. But make that little wee one bigger, and make it point upwards where it can do some work.I was thinking they'll need to keep that pusher prop to help offset the very slight drag penalty of the static mast structure.

[Lonewolf_50]

And when the cube/square rule rears its big, ugly heard, when they try to scale that thing up ... :p

Interesting looking prototype, however.

[ORAC]

Not sure if the designer ever heard of the KISS principle, but only it's mother could love it..... :ouch:

AW&ST: Volocopter - Safety and Simplicity in Numbers (http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:a68cb417-3364-4fbf-a9dd-4feda680ec9c&plckPostId=Blog%3aa68cb417-3364-4fbf-a9dd-4feda680ec9cPost%3aee5d4cec-2142-4a5b-bc61-38faa193bff9)

A strange, 16-propeller vertical take-off and landing craft has been awarded the Lindberg Prize for Innovation at the Aero-Friedrichshafen 2012 airshow in Germany. It is an example of the unusual configurations made possible by distributed electric propulsion.

http://sitelife.aviationweek.com/ver1.0/Content/images/store/1/11/81d21a98-b61f-48a9-abe5-2d99356ae40e.Full.jpg

The VC1 was first flown by Karlsruhe-based e-volo in October 2011 as a proof of concept for its Volocopter, an aircraft that uses multiple small, electric-powered, fixed-pitch propellers for lift and flight control. The array of battery-driven props provide redundancy for safety and are individually controlled via a fly-by-wire system to provide flight control via differential power by varying motor rotational speed in response to joystick inputs.

http://sitelife.aviationweek.com/ver1.0/Content/images/store/0/5/503617ca-a8bd-4e80-8535-3e59f3b335fa.Full.jpg

The single-seat, four-armed VC1 measures 17ft x 17ft and weighs 80kg empty, and could fly for about 20 minutes on current battery technology, says e-volo. The company is now designing a two-seat VTOL aircraft, the Volocopter VC Evolution 2P, that mounts its 18 props and motors on an umbrella-like structure above the helicopter-style fuselage. The aircraft is being designed to comply with European ultra-light (ULM) regulations.

http://sitelife.aviationweek.com/ver1.0/Content/images/store/4/14/a4680410-e854-46a2-8e2e-ffc22bc60193.Full.jpg

Fitted with a pusher propeller for forward flight, this aircraft will have a take-off weight of 450kg, speed exceeding 54kt (100km/h), altitude capability of at least 6,500ft and a flight time of more than an hour thanks to a serial hybrid power system - with a "range-extender" internal-combustion engine that will recharge the batteries in flight.

http://sitelife.aviationweek.com/ver1.0/Content/images/store/9/8/498d73d6-60a7-4190-88a9-f3aba92375a1.Full.jpg

Awarding the prize to e-volvo, Erik Lindbergh (Charles Lindbergh's grandson) said: "We believe that the development of the Volocopter holds significant promise to radically change short-distance transportation." The Lindbergh Foundation's prizes are intended to promote advances in green aviation.

[Dave_Jackson]

A new article in Rotor & Wing.

Designer of Electric Helo Reflects on 2011 Flight Tests (http://www.aviationtoday.com/rw/topstories/Designer-of-Electric-Helo-Reflects-on-2011-Flight-Tests_77333.html#.UGMhyUJyXZs)

Dave

[AdamFrisch]

Interesting. He pretty much confirms what I'd guessed, that reduction gearboxes are the weak links in helicopter design. I thing a genset powered by turbines and a fully electric main and tail rotor is the future until power storage increases. It might not save much weight for now, but it will be cheaper and more reliable. But most importantly safer, as the genset can fail and you could still land on battery power.

[riff_raff]

Interesting. He pretty much confirms what I'd guessed, that reduction gearboxes are the weak links in helicopter design.AdamFrisch-

If "gearboxes are the weak link in helicopter design", why do most modern rotorcraft still use 2 (or even 3) turboshaft engines, at least 2 separate hydraulic systems, at least 2 separate electrical power bus circuits and generators, at least two sets of pilots and controls, etc., but only a single MRGB?

Blaming a mechanical system for problems with rotorcraft is what one would expect from an electrical engineer. The reality is that the MTBF record of any current rotorcraft gearbox is far better than that of any rotorcraft electrical system.

[Dave_Jackson]

This might, or might not, be of some interest. http://www.unicopter.com/NoIdea.gif

Annual Safety Review easa.europa.ex (http://easa.europa.eu/communications/docs/annual-safety-review/2011/EASA-Annual-Safety-Review-2011.pdf)


Dave

[riff_raff]

Dave_Jackson,

Thanks for the link to the accident report.

Yes, the report shows a slightly lower number of rotorcraft accidents attributable to engine related systems versus gearbox related systems. But one might argue that does not mean engine systems are more reliable or have a lower MTBF. In fact, one might argue that the only reason engine failures have not produced more accidents is due to the functional fault tolerance provided by a single main gearbox with multiple engine inputs.

[Dave_Jackson]

Hi riff_raff,

Today a person asked me for information on a little known Flettner proposal in the US after WW2, so a request was put on PPRuNe to see if anyone knows anything.

It happens to mention the gearbox, but please don't think that I am picking on gearboxes. http://www.unicopter.com/Wink.gif


Dave

[Peter-RB]

e-Volo on you tube

Being a child form the Steam age I do not kow how to capture and lift the you tube content, but I have just watched a very short video of a guy and his two friends who actually flew a battery powered one man sit on hovering platform, I urge those who are interested in all things of a Heli type nature to take a look it is brilliant.:D:D

Peter R-B
Lancashire

[AdamFrisch]

I agree. The future of all flight is electric. Here's a thread I started a couple of years ago.

http://www.pprune.org/rotorheads/426523-future-helicopter-electric.html

[Agaricus bisporus]

That'll be a pretty dismal future until battery/fuel-cell technology improves by a couple of orders of magnitude. Give it 30 years and just maybe.

[skadi]

Maiden flight of the e-volo project:

Revolutionary green helicopter makes maiden flight | Vertical Magazine - The Pulse of the Helicopter Industry (http://www.verticalmag.com/news/article/Revolutionary-green-helicopter-makes-maiden-flight#.Uo4snZSG2UF)


skadi

[2Sticks]

The first manned flight of the Volocopter has just taken place. D-MYVC can be seen in this video piloted by the CEO of Volocopter:

OazFiIhwAEs


Fascinating - will be interested to read the views of all the aero engineers out there as to the future prospects of this. Good video.:D
2Sticks

[Vertical Freedom]

Impressive lift off......can't wait to see it Auto ��

[Phone Wind]

An interesting video. However, I think it still only has a 20 minute endurance and a 55 kt cruise speed so there's a long way to go before it has much commercial use as a manned vehicle concept.

The company states that it will still fly in the event that a number of rotors fail, but the number isn't stated, although they do also say that it's fitted with a parachute.

[Ian Corrigible]

Reminds me of another 'distributed lift' project from a few years back, which had some interesting potential (and which could have sent tinfoil prices skyrocketing). Never saw a single mention of it in the press, but a conceptual image does exist on the web:

http://www.ernstgamper.ch/images/dma_2.jpg

I/C

[Ascend Charlie]

It looks like a single sidestick to control 4 axes - pitch, roll, yaw and vertical (collective).

Be interesting to see if the average joe can get a pure yaw or vertical movement without the natural movement of the hand and wrist bringing in some cross-coupling, with unwanted roll/pitch/whatever.

But this fella seems to do OK and even lets the stick go.

[mickjoebill]

The use of Tethered uav and drones is being explored and results so far are encouraging. Power goes up the wire so fewer batteries needed.

I see a can of regulatory worms labeled manned, powered, tethered flight:)

Another can of worms, do regs cover a commercial, fare paying passenger flight, which is controlled via tether by pilot on the ground?

Enormous redundancy can be built in at a minimal penalty...

Mickjoebill

[Arnie Madsen]

.

Arthur Young was doing this stuff in the 1930's https://en.wikipedia.org/wiki/Arthur_M._Young#/media/File:Model_helicopter_being_controlled_by_its_creator_Arthur _M._Young.jpg

[Evil Twin]

That is actually pretty impressive really. What is the power source, batteries I know, but how many, type, endurance etc?

He looked pretty relaxed stooging around at lethal levels on the first flight in an experimental aircraft.

Well done.

[skridlov]

Ever since the idea of electrical power for cars became a serious proposition rather than speculation one thing keeps occurring to me and I think it may be relevant to the discussion here. Interchangeable modular batteries. The practicality of recharging associated with cars has always looked like a show-stopper to me. It's difficult enough to find anywhere to park, let alone with a recharging socket conveniently available. However the infrastructure for refuelling with petrol is ubiquitous. It's obviously a gross simplification but modular rechargable batteries which can be rapidly swapped would eliminate the problem to some extent. Of course getting agreement amongst manufacturers - whether of car or aircraft - for a common modular battery format is likely to be all but impossible.

[whoknows idont]

skridlov: The idea exists since exactly 120 years now and was in service between 1910 and 1924 called GeVeCo. The biggest modern battery-swapping project Better Place (https://en.wikipedia.org/wiki/Better_Place) went bankrupt in 2013. They erected 21 robotic swapping stations in Israel and 17 in Denmark.
Apparently Tesla Model S is also capable of battery swapping but only one swapping station was built and Tesla seems to have abandoned the project due to low demand and high costs compared to regular fast-charging.

For helicopters I think with today's battery technology, the way to go is gas turbine generated electricity. Buffer battery for peak loads / takeoff power. 5 minutes purely electric flying ability for emergency landing in case of engine failure. :ok:

[riff_raff]

....I think with today's battery technology, the way to go is gas turbine generated electricity.....DARPA just gave Aurora Flight Sciences $89 million (http://www.darpa.mil/news-events/2016-03-03) to build a flight demonstrator of their Lightning Strike hybrid gas turbine/electric VTOL aircraft. The stated performance goals are 10,000-12,000 lbs GVW and 300-400 kts max speed. It uses a single 5600 shp AE1107C turboshaft engine (similar to the V-22's engine) to drive three generators.

[Ian Corrigible]

A few years ago EADS was touting eCO2avia (http://www.aerospaceamerica.org/Documents/AerospaceAmerica-PDFs-2013/June-2013/International_Beat_Aerospace_JUN2013-3.pdf#page=2), a diesel-electric solution with two OPOC (http://ecomotors.com/) diesels charging two batteries via electric generators, and with electric motors driving the rotors. The concept, which was previously mentioned in the 'Electric Sikorsky' (http://www.pprune.org/rotorheads/421752-200hp-electric-sikorsky.html#post5826283) thread, had the potential to free designers from the traditional layout constraints of mechanical transmission helicopters:
The hybrid system architecture allows the main rotor and its electrical drive to be tilted forward during cruise flight. This enables the helicopter’s fuselage to remain at its optimum alignment with the airstream, minimizing aerodynamic drag and thereby reducing the power demand and the fuel consumption. Since the tail rotor has no mechanical linkage to the main rotor and its power source, it can be turned off at higher speeds. During these flight phases, stability and control as well as balancing of the rotor torque are provided by the aerodynamic properties of the helicopter’s tail fin and rudder. [Source] (http://northamerica.airbus-group.com/north-america/usa/Airbus-Defense-and-Space/news/press.20100608_eads_iw_ila_hybridheli.html)
The concept went 'quiet' shortly after its unveiling, though interestingly Airbus and Siemens just signed an agreement (http://www.siemens.com/press/en/pressrelease/?press=/en/pressrelease/2016/corporate/pr2016040246coen.htm) to cooperate on the field of hybrid electric propulsion systems.

I/C

[Lonewolf_50]

Since the tail rotor has no mechanical linkage to the main rotor and its power source, it can be turned off at higher speeds.
Just make sure nobody/nothing cuts that wire bundle. :)

[Self loading bear]

?New? Ideas about electric helicopters:

Identified-Flying-Object (https://www.designboom.com/technology/jet-capsule-identified-flying-object-03-23-2017/)

Cheers SLB

[Ascend Charlie]

Love the dreamer's pic of the Identified Flying Object "Landing in the streets" - no cars visible anywhere, the Object floating down between palm-lined footpaths, and hasn't yet deployed the landing struts at 10'agl.

That Object also needs special ground steps and boards to allow people to access the cabin - where will they be kept? Nice little cgi bit of mental m@stur... well, you get the idea.

[Lonewolf_50]

A. Charlie: it appears to need two or three parking spots as compared to, say, a Fiat 500.

[Ascend Charlie]

But you wouldn't park your Bambino on a pedestrian crossing, beside a "no parking" yellow line. But it's OK, no cop cars in sight.

That parachute might reduce their terminal velocity from 120kt to maybe 115.

[pilot_tolip]

What's the likely hood of electrically powered helicopters becoming a reality for GA and Commercial operations?
I see from this article that 'Tier 1 Engineering' is making some inroads https://www.tier1engineering.com/news/093016

[Ascend Charlie]

It takes 5 minutes to refuel a helicopter with liquid fuel, and it is good for another 2-3 hours. Refuel, 2-3 hrs work, and so on.

It takes overnight to recharge a battery pack, and it is good for maybe 45 minutes. Then on the ground till recharged, or have another massive, heavy and expensive battery pack to swap out.

A quantum leap in energy density in batteries is needed for it to happen for a USEFUL human-carrying machine.

[206 jock]

And don't forget, even Elon Musk can't change the laws of physics: to propel an object into the air will always take the same number of electrons and it takes time and infrastructure to put electrons into batteries, even if there is a quantum leap in energy density of batteries.

With a single onboard charger on a Model S Tesla, being charged from a normal (US) 110V outlet, you get 5 miles of range for every hour of charging. From 0 to 300 miles of range takes 52 hours.

Given the inevitable safety margins required for an electrically powered helicopter, I cannot see it ever being a practical proposition.

[Less Hair]

Just put the batteries in modules. Drop the spent one and take some fully loaded one instead. No need to wait for charging.

[Bell_ringer]

Just put the batteries in modules. Drop the spent one and take some fully loaded one instead. No need to wait for charging.

Batteries weigh a ton, they often are distributed around a vehicle to balance the weight distribution.
Having a removable pack makes that more challenging.

[GrayHorizonsHeli]

?New? Ideas about electric helicopters:

Identified-Flying-Object (https://www.designboom.com/technology/jet-capsule-identified-flying-object-03-23-2017/)

Cheers SLB


so, those ladders to get in and out?
do I need to FedEx them to every location I plan on landing at to arrive before I do?

[Self loading bear]

so, those ladders to get in and out?
do I need to FedEx them to every location I plan on landing at to arrive before I do?

Grays,
How should I know that?
I am Self Loading
I guess they are also urgently looking for Self Loading Batteries.

Cheers SLB

[Arnie Madsen]

Electric Helicopter
Oskar Stielau
Auckland, New Zealand

During September 2019, inventor Oskar Stielau, based in Auckland, New Zealand, started the development of an experimental electric helicopter. He starting formulating the idea of building an electric helicopter in 2014. The helicopter model is a conventionally powered Mosquito helicopter which he built in 2008 and Stielau flew as a gas-piston engine helicopter for 60 hours. The rotorcraft has now been completely converted into an electric helicopter.

https://evtol.news/stielau-electric-helicopter?fbclid=IwAR1uTnJpVg6kQbS6m1cYvBNxivYO22IFDkCYiHSL J985zSeTma7kmT2vMDQ

[Arnie Madsen]

.

Video of the Oskar Stielau Electric in flight .... and demonstrates an auto.

https://www.youtube.com/watch?v=T6-BV-6dKvg

[Ascend Charlie]

In a real auto, as a result of electrical failure, there will be no tail rotor operating, as it is run by a potentiometer adjusting electric power to the 7 rotors.
In a real auto, will the dead electric motor drag the RRPM down, or is there a freewheel unit?
In a real helicopter, they keep the electrics where they belong, in batteries and generators, not running the show.

[aa777888]

This guy's work is impressive. A bit simplistic, obviously, but still quite well thought out. It would not take a lot of extra work to make the electric power source for the main and tail rotors fully redundant. Going to an even number of tail rotor motors makes this trivial, just split them half and half. For the main rotor motor slightly less trivial as actual power electronics would be involved but nothing that hasn't been done before in many other applications. One might even consider two motors but that starts to generate the usual diminishing returns in terms of cost/complexity/size/weight.

Even the 27 minute endurance is impressive given the limitations of today's battery technology. It is, unsurprisingly, very commensurate with drones of all sizes. Stating the obvious, until someone comes up with electrical power storage systems with approx. 10 times the power density currently achievable, prime power will continue to derive from piston and turbine sources, even if some of that power is converted to electrical energy for an electric anti-torque system. And that also does not address the problem of charging time.

For me the real take-away is that, looking at this effort, and Bell's work also, electric anti-torque systems using a multiplicity of rotors/motors clearly seem to be the future. No drive shafts. No gearboxes. With appropriate design, a much higher degree of failure tolerance and safety. Improved authority. Less noise. Less maintenance. With proper engineering, what's not to like about it? A bigger alternator, a small battery backup, a two channel control unit, and none of this is rocket science anymore.

[Arnie Madsen]

I have followed Oskar's testing for a while now
I believe he uses the original Mosquito helicopter freewheel unit

He was very thorough , all his initial testing was tethered flight , measured lift and thrust and electric consumption in all parameters.

He demonstrated an auto in the video ... how can anyone say it will not auto ??
Yaw control would not be lost if main electric motor failed
Loss of yaw control would require total battery failure ... big difference.

Beloved Billion dollar Sikorsky engineers built an all electric Hughes 269
But did not show it actually flying

Home built experimenter Oskar built one from his grocery money
And it actually flies.
Big difference

[IFMU]

Beloved Billion dollar Sikorsky engineers (BBDSEs) built an all electric Hughes 269
But did not show it actually flying

Correction: BBDSEs outsourced the build of an all electric Schweizer 300 and it never flew. Maybe they outsourced it to the wrong people. Or maybe they should have not oursourced it, and used the project to develop their young talent like we did on X2.

[CRAN]

I think the future of the helicopter is definitely electric, but it will take time. All of the drive and control technology exists and has done for decades in some instances. The obvious missing ingredient is electricity storage. Until we can store electricity in a much more energy-dense fashion electric helicopter will not be truly viable technically or more importantly commercially for operators.

Hybrid gas turbine generators might be an intermediate step, but it would take a smaller manufacturer or startup to do this cost effectively, the big boys would bring all their friends to the party and make it too expensive.

Dont fear the coming of electric drive, it will make helicopters better for all of us. Similarly, don't fear the eVTOLs, a modern electric helicopter would out perform them all.

I shall miss the startup sound of a Rolls Royce engine though.

cran

[[email protected]]

He demonstrated an auto in the video ... how can anyone say it will not auto ?? he demonstrated a descent to a flare and a power recovery - was it actually in auto? What would be better proof is a full touchdown auto.

In the other video he hasn't learned how to prevent sink at the end of a quickstop either and seems blissfully unaware of the proximity of his tail to the ground.

Don't get me wrong, I admire what he has done but he is only a small part of the way there.

[Bell_ringer]

Outside of specific applications we aren't going to see a plugin helicopter any time soon, we are still too far away from getting light-weight, efficient power storage.

Hybrids, on the other-hand, is a more interesting area.
The use of motors to power the tail rotor (ala Bell EDAT), or for supplemental and emergency power requirements are more practical uses.
In mainstream applications, the integration of electrically driven systems will be more evolution than revolution.

[MLH]

Nice to have autorotation as a backup in the event of a main power bus failure vs. becoming a brick with a multirotor.

[Arnie Madsen]

The smaller the aircraft , the better electric works (drones etc) .... much larger and results diminish .... something to do with molecules of air on a small propeller at high rpm .... compared to larger blades at lower rpm. (small works better)

The real drawback is battery weight of course.

Using Old school lead-acid batteries you needed 500 lbs of battery to equal the energy of one gallon of gasoline
Modern laptop type batteries are better , maybe 300 pounds or so.
But even more problematic is the machine ends up carrying a lot of dead weight (dead batteries) as the trip progresses.
Whereas gasoline is consumed during the trip and the machine progressively becomes lighter.

Take Tesla for example ... they claim up to 300 mile range under moderate driving , but by the end they are still carrying thousands of pounds of dead weight of now useless battery ... which requires many hours to recharge ..... whereas a normal car you just add a couple of gallons of compact light weight gasoline and come home.

Gasoline is a very low cost until our governments add all the taxes . It is a very potent form of energy , pretty hard to beat , there is lots of it and it is safely distributed everywhere .

[WillyPete]

I have to ask this:
What is the use of going with a traditional anti-torque rotor placement if you're rewriting the helicopter playbook?
What if, instead of an array of small rotors on the tail as he has now, he had two smaller sets of rotors either side of the aircraft?
He obviously isn't using a large airfoil at the back to induce force when at speed, and isn't using a linkage to the MR/gearbox.

So what benefits to the keeping TR in the traditional location instead of a more compact system, which would even have an added benefit of providing forward/backward thrust and thus reduce the demand on the battery by the MR?

[Ascend Charlie]

compared to larger blades at lower rpm. (small works better)

Maybe with a scale model, but in real life, a large rotor moving lots of air to a smaller speed is far more efficient than a teensy rotor moving small amounts of air to a much higher speed. Losses around the tips compared to the size of the lifting surface. A glider with a high aspect ratio is more efficient than a small wingspan.

[RINKER]

I think small single or multiple rotors on long tail boom more efficient due to leverage
rather than bigger propellers close to cockpit.
R

[Reely340]

We know weight / stability of current helicopters works, with a certain margin.
E.g. lightening the helicopter's structure (mast, blades, frame) won't work or it'd been done already.

Swapping in an electirc motor (and possibly gearbox) for the current combustion type might give an weight advantage in case of piston-engines but definitely will incur a hefty penalty when looking at recent turbines power/weight ratio.

For the sake of this argument we'd kindly and assume NO weight penantly when switching to electirc drive train.
Considering that takeoff in an S300C at 3000ft and ISA+30 with two wellfed occupants and full tanks is not possible,
we can assume that the power source must not be heavier than AVGS.
Looking at available space the volume of the powersource might be al little more voluminous per MJ (energy measure).

Looking at the graphics we may pick anything to right of "Gasoline" (weight issue) and upward of LNG if we want similar endurance and tank volume as with AVGAS.

If one looks at where Li-Ion Battery oder Zinc-Air Battery is positioned it becomes quite evident that current production technology work work:
We'd need twice the physical tank volume for a Li-Ion battery (zinc-air would be same volume as avgas tank)
but would get far less then one tenth endurance due to lacking energy/weight density.

That would insinuate the S300C would be out of "fuel" after 20 Minutes hovering.

BUT if the tech guys manage to get Lithium Borohydride "to fly" (pun intended) the world (of piston helos) would change:
A LiBH4 battery packs the energy both tighter (volume) AND lighter (weigth) than any of our beloved liquid gasolines.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1920x1200/1920px_energy_density_svg_06ef3f66368c423e802619bcdd70bfdc44 4dc2de.png
Energy sources grouped according to volume density and weight density

[Reely340]

The smaller the aircraft , the better electric works (drones etc) .... much larger and results diminish .... something to do with molecules of air on a small propeller at high rpm .... compared to larger blades at lower rpm. (small works better).

Bad example. Electric drones only work because customer is happy with 20 mins endurance.
Load them up to carry juice for the 3h helo pilots are used to and they'd not be able to takeoff.
Beef up engines, rotors and electronics so that they be ableto fly, you#d be back to square one,
having to add more battrey to achive 3h ... ad infinitium.

=> Li-Ion won't cut it, ever. If you want a combustion helo's endurance, that is.
As a 20 min toy they do extremely great.

[Reely340]

BUT if the tech guys manage to get Lithium Borohydride "to fly" (pun intended) the world (of piston helos) would change:
A LiBH4 battery packs the energy both tighter (volume) AND lighter (weigth) than any of our beloved liquid gasolines.

let me add that above is true IF and only if that new Lithium Borohydride Battery (https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiy6NfIoNXvAhWOyIUKHfqOBbMQFjABegQICBAD&url=https%3A%2F%2Fcleantechnica.com%2F2014%2F05%2F26%2Flithi um-borohydride-battery-whole-new-generation-solid-state-batteries-possible-thanks-new-research%2F&usg=AOvVaw0R6q7r0IheJEAPm5WRO4Ig) will provide its massive energy in a fast fashion.
If fully darining it take 3 years, it might be great in sattelites but not in high yield applications like helos.

[cattletruck]

I must admit I remain very impressed with Oskar's ingenuity, besides the battery limitations I'm sure his rig lets him explore other ideas such as his quad electric tail rotors. If I were ever crazy enough to undertake a similar venture I would relocate the tail rotors to both sides like elephant ears but on shorter booms. This will then allow both sides to provide anti-torque in the hover and when moving forward one side can be reversed so that both sides can provide a propelling force.

Thanks for the graph Reely340, it really does put batteries in perspective (and also wastage of energy by liquid fuels).

[MeddlMoe]

This Technology is also very promising for hydrogen powered electric aircraft:
https://www.fraunhofer.de/en/press/research-news/2021/february-2021/hydrogen-powered-drives-for-e-scooters.html

[MeddlMoe]

If I were ever crazy enough to undertake a similar venture I would relocate the tail rotors to both sides like elephant ears but on shorter booms. This will then allow both sides to provide anti-torque in the hover and when moving forward one side can be reversed so that both sides can provide a propelling force..

The Airbus Racer configuration?

[MLH]

The Airbus Racer configuration?

Or a coaxial design.

[WillyPete]

I must admit I remain very impressed with Oskar's ingenuity, besides the battery limitations I'm sure his rig lets him explore other ideas such as his quad electric tail rotors. If I were ever crazy enough to undertake a similar venture I would relocate the tail rotors to both sides like elephant ears but on shorter booms. This will then allow both sides to provide anti-torque in the hover and when moving forward one side can be reversed so that both sides can provide a propelling force.

Thanks for the graph Reely340, it really does put batteries in perspective (and also wastage of energy by liquid fuels).
Yeah this is what I proposed above.
Don't see why it couldn't work.

[Fark'n'ell]

A three phase electric motor weighs close to 3000 lbs and draws about 300 amps.I would think a battery to supply that amount of energy for a small amount of time would weigh about the same..Have'nt started on the airframe yet

[Arnie Madsen]

I must admit I remain very impressed with Oskar's ingenuity, besides the battery limitations I'm sure his rig lets him explore other ideas such as his quad electric tail rotors. If I were ever crazy enough to undertake a similar venture I would relocate the tail rotors to both sides like elephant ears but on shorter booms. This will then allow both sides to provide anti-torque in the hover and when moving forward one side can be reversed so that both sides can provide a propelling force.

Thanks for the graph Reely340, it really does put batteries in perspective (and also wastage of energy by liquid fuels).
As far as the tail rotor , Oskar said he tested many different methods ... and was somewhat surprised that multiple independent small rotors were the best .

It is agreed that the current test model looks like a thorn bush on the end of the boom but I expect he will tidy it up some day ..... on that note it appears that Bell Helicopters came to the same conclusion with their multiple electric tail rotor prototype.

Another thing to keep in mind is that Tesla cars took a giant leap forward with their motors .... something like permanent magnets on the armature itself which makes tremendous torque ... I am not an expert on electrics but have the proper info on a different computer and will post it later.

Oskar is not using a Tesla motor but found something unique for his main power ... later I will post it also.

======================
EDIT to add pictures

.
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/657x448/oskar_helicopter_electric_tail_6d6adaee76566a492b0c2dafc3991 2095344fa6f.jpg
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/504x546/bell_429_e_electric_3eb6fc87a071c2bbe000ea7ca23cfb202a8f96ad .jpg

[CTR]

Looks like Bell covered the open rotor “thorn bush” configuration also in their patent for the electric tail rotor.

Great minds think alike.
https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/1334x750/50126928_ce1e_4938_8dfe_e06df38d34a7_d31fc7b8f826dc780151d58 b8b5181d115413925.png

[skridlov]

https://www.theverge.com/2022/5/26/23141849/joby-aviation-faa-certification-part-135-evtol

[Lonewolf_50]

https://www.theverge.com/2022/5/26/23141849/joby-aviation-faa-certification-part-135-evtol From the above link The company says it aims to have a full-scale air taxi service in operation by 2024. Who is their customer based believed to be? That might be a very pricy cab ride. :eek:

[Winemaker]

One question is where these machines, if certified, will be allowed to land. It's not as though one can sort of randomly pop down and pick up passengers....... Duration might also be an issue..... My brother lives on Pine Lake in Sammamish, Washington; one of the residents wanted to use his helicopter to commute to work; he was allowed a single landing per day with time limitations over vociferous opposition of other residents.

[Less Hair]

If the market would require all those electric VTOLs wouldn't we see way more helicopters used today for short passenger flights on all those expected drone routes?

[ShyTorque]

A disadvantage of battery powered aircraft is that they don’t burn off fuel in flight. The aircraft weighs the same at destination as on departure and the performance remains the same throughout.

Not really a problem for a small helicopter remaining at low altitudes, but definitely so for something larger, a utility aircraft or an aeromedical/ SAR one.

[601]

nasa have actualy just developed new wire cable to convert the flat electrons into round ones, by narrowing the cable down (like a funnel) it squashes them into a ball which greatly increases the rate at which work can be done

Gee it is amazing how technology solves everything.

It has been discovered that making electrons into small cubes and converting them into magnets solves the problem having wasted space around spherical electrons in a cable and flat electrons (no power left at the end of the cable)
It also dispenses the need of the permanent magnets in the motors. Replacement magnets are fed in as cubical electrons

However, research is still required into the square sectioned cable and the difficulty of moving cubes of electrons, that are magnetically attracted, around a bend in the cable and how to convert the cubical electrons into large permanent magnets.

Word has it that they may solve this problem in 20 or 30 years.
http://www.dumbscience.com

[Winemaker]

Gee it is amazing how technology solves everything.

It has been discovered that making electrons into small cubes and converting them into magnets solves the problem having wasted space around spherical electrons in a cable and flat electrons (no power left at the end of the cable)
It also dispenses the need of the permanent magnets in the motors. Replacement magnets are fed in as cubical electrons

However, research is still required into the square sectioned cable and the difficulty of moving cubes of electrons, that are magnetically attracted, around a bend in the cable and how to convert the cubical electrons into large permanent magnets.

Word has it that they may solve this problem in 20 or 30 years.
http://www.dumbscience.com
Well I'm holding out for the toroidal electrons, as getting zapped would be a delicious experience. Plus they could just slide down the outside of (round) wires greatly reducing friction.

[fdr]

A disadvantage of battery powered aircraft is that they don’t burn off fuel in flight. The aircraft weighs the same at destination as on departure and the performance remains the same throughout.

Not really a problem for a small helicopter remaining at low altitudes, but definitely so for something larger, a utility aircraft or an aeromedical/ SAR one.

A disadvantage of battery powered aircraft is that they don’t burn off fuel in flight. The aircraft weighs the same at destination as on departure and the performance remains the same throughout.

Not really a problem for a small helicopter remaining at low altitudes, but definitely so for something larger, a utility aircraft or an aeromedical/ SAR one.

unless they can be jettisoned... :}

Good point on efficiency, though. Fuel fractions are a major driver of excess power available.

Nick P had commented on the mass of electric motors vs engines, and his figures are correct for most motors, but there are some stunning motors available. A long time back, a certain French inventor came up with a nice little design that was plonked into the back end of a B206 for testing, and it was lighter than the RGB that it replaced. The power cables were about a wash. The motor design was pretty neat, but the tech owner was particularly sensitive to IP issues and barely gave information to the engineers to do the test. The size form was neat, and the output was scalable. The rotor efficiency can be improved by an incremental margin, but not enough to make up for the battery power density. What would be intriguing would be to have a hybrid design using the same novel motor as a generator to reduce mass, and using same for drives. staying with a lightweight generator with a reduced fuel load and using high density batteries... maybe there is a future. The novel motors were light, really really light. Haven't spoken to the guy for many years, his paranoia may have had justification, but Lordy it made it hard to get anything done.

As to what can be done on the rotor, about 25 years ago (? 97? could have been around 2003...) there was a neat little engineering note in the AIAA JoA that covered some interesting CFD done with Wayne Johnsons CAMRAD II on autorotation of a disk (+ dangly bits) applying lift enhancing tabs, LET's to a rotor. There was no methodology of the structure which has been a pain for implementation. I had been doing tabs on propellers for about 10 years by then, and had transferred that to flight testing on a 12":1' scale helicopter. The CFD gave an improvement of 20% in autorotation, but used a design that was known to be far from optimal from the prop and rotor testing, but was at least interesting, as LETs alter the L/D in such a way that it is conceivable that they preclude autorotation in a fixed geometry. In the end, auto worked OK, but it was a very uncomfortable flight getting out there to try it the first time. Parachutes from a helo have some obvious technical drawbacks. Glad to never have to see if the technique would work to remove the blades without removing the top of the cabin.

The curious outcome suggested that the variation of the coefficients of CL and CD were effective as follows...

Baseline 63105 blade, NACA smooth, rotor stall at 82% Nr, measured fuel flow, 62 units( fuel flow and engine power were quite linear)
MOD 1, (leading edge of blade, certified later) rotor stall at 77% Nr, 58 unit fuel flow... pitch link loads reduced
MOD 1 & 2 (adding an LET...) rotor stall at 68%, 39 unit fuel flow. loads per MOD 1. Acoustic spectrum attenuated, but added a 1600hz line
collective loads measured and no significant change from baseline, other than SR was reduced, as was vibration.

The MOD 2 change appeared to be considerable, and raised questions about the accuracy of the measurements, but the Nr was strobed and was valid, and the stunning control effect was that the baseline chopper gets to LTE about the same time it runs out of rotor, Mod 1 recovers some pedal at the stall, indicating the torque demand has definitely improved, and then with the tab, approaching the stall, the pedal demand was 50% of the left pedal of the baseline case. The last check before going into translational flight and autos was to go to idle, set full up collective and see if the rotor could accelerate, and it did, was able to accelerate and lift off and hover with a full up collective, Unmodified, the rotor would not accelerate to flight speed. This little project languished as it became secondary to modification to jet aircraft, and my helicopter had one bit of design that made high speed testing of a tab uncomfortable from a risk aspect, it had a TRB that was not confidence building for dropping bits off. I did some failure tests, and videoed the tabs departing from the rotor, and at low speed they had departed merrily away from. the TR disk, but in forward flight that may not have been the case. Was working up to testing NOTAR or fenestron before going back to a light structure TRB, but a UH-60 TR would have worked... The tabbing model CFD'd in JoA I also flew, and it was not effective at improving CL/CD, it did definitely increase CL, but that is never in doubt, only whether the rotor AOA puts the CL/CD into the position where stunning changes occur. Tabs shift CL by around 0.4 - 0.6 CL for the same AoA, dependent on multiple parameters but that is indicative. How it is done on a rotor is somewhat more interesting than the CFD model, in the real world that config made almost no improvement.. hardly a surprise. The CD however is altered stunningly at mid AOA levels, like those associated with props and rotors and fans, sections that are constrained from approximations of ideal blades. We did the tabs as well on the CART 2 test rig of NREL, and that was effective, but then the CART 2 section is a pretty awful analogue of optimised wind turbine blades. Torsion loads were no factor which was similar to the rotor. The tabs do mitigate a bit the hysteresis of the coefficients from pitching effects, the stuff that Boeing Vertol was trying to sort out on the CH47s VR7 blade section by using VGs. John C Lin and co of NASA showed how wild the CD shift could be, however the implementation on a propeller, rotor or fan blade has some constraints that make the hover value that I got closer to the practical limit than Lin, Storms, Carranto and co's theoretical limits. If anyone has a test vehicle that is NOTAR or has a fenestron, (or a UH-60...) the LET is worth the candle IMHO.

[jimjim1]

There are a few companies spending huge sums on drone style Air Taxis.

Also Bell and Airbus have something in this area too.

Most info from https://craft.co/lilium/competitors.

The three below apparently total about 2400 employees. These are engineers who are all in great demand and will not be cheap. Total investment so far is over $1B.

I have found:-
## Joby Aviation ##
Santa Cruz, US

845 employed

Funding raised $691M

## Lilium ##
Munich, Germany

In 2020 employed 400 people, now 908

Maybe raised something like $500M

NasdaqGS

Sept 2021 $10
May 2022 $ 2.82
Market Cap $814M

## Velocopter ##
Bruchsal, Germany

530 employed
$372M raised

[WillyPete]

A disadvantage of battery powered aircraft is that they don’t burn off fuel in flight. The aircraft weighs the same at destination as on departure and the performance remains the same throughout.

Not really a problem for a small helicopter remaining at low altitudes, but definitely so for something larger, a utility aircraft or an aeromedical/ SAR one.


This may be true, but if total powertrain and battery weight is less than standard ICE engine and full fuel weight, then it evens itself out.
The gearbox will be a lot lighter and less complex if the TR is electric.

I too would expect fossil fuel aircraft to hold their place quite well in the utility and heavy load roles. I don't think that's the target though.

[sitigeltfel]

A container being used to store lithium batteries belonging to an an electric helicopter company in France caught fire yesterday.

A rough translation of the story with links to the press report and company website....

"More fear than harm, yesterday morning on the site of the Caromb-based company Electric Aircraft concept, route du Barroux. About twenty firefighters were dispatched at 8 a.m. for a fire that started with a double risk.
This not only contained 200 kg of lithium-based electric batteries but was also, while being secure, adjoining a building. It took the detachment of the mobile chemical intervention cell (CMIC) of the department (Bollène and Avignon) to put an end to the fire.
The used batteries had to be covered with two tons of sand quickly brought in by the municipality to smother the fire while the firefighters protected the building by drowning the facade. Fortunately, the fire did not spread and the danger of toxicity was averted in part thanks to the absence of wind that morning. Two hours later, the operation was completed.
According to the Carpentras gendarmerie company, the start of the fire would be linked to the high temperatures."


https://www.laprovence.com/actu/en-direct/6853828/caromb-un-feu-de-batteries-electriques-au-lithium.html

Whisper (http://www.eac-whisper.com/)