To buy, or not to buy: that is the question

[Dave_Jackson]

I have been given the opportunity to purchase shares in a new company that is building a helicopter called the ELECTROTER. The owner of the company says that his helicopter overcomes the rising cost of fuel.

It is powered by an electric motor, and when not being used it is parked nose up on a ramp facing the wind. He says that the wind Autorotates the rotors and charges the battery.

Is it worth buying the stock, or is the owner giving me a blow-job?

[slowtyper]

I'm selling shares in the Sydney harbour bridge if you would like to put your money into something solid,good position,great returns.............:E

[SASless]

Davie, there is a world of difference between a "snow job" and a "blow job"!

It is intuitively obivious, honest!

[Disguise Delimit]

I'm selling shares in the rotating ramps that the helicopter is parked on. It is built in the middle of a large field, and can turn in any direction to face the wind. There is a hydraulic lift that tilts the ramp skyward, massive shackles that grip the skids and stop the chopper from sliding off backwards, and even an electric fan that provides the wind when there isn't any to turn the rotors.

However, because the ramp is out in the middle of a field, there probably isn't any power supply for the fan, so I have made it to operate off the aircraft's battery!! There is another fan to blow away any snow from the rotor blades (because they won't autorotate if they are under snow) and another electric heater to warm up the cabin on those snowy cold days.

I have found that the aircraft battery goes flat fairly quickly, so I added a turbine motor to power the helicopter if the battery goes flat:ok: .....

[Dave_Jackson]

Sasless,Davie, there is a world of difference between a "snow job" and a "blow job"!
You naughty boy; to try and change the subject of this thread to drugs and sex. http://www.unicopter.com/Wink.gif

[rotornut]

Reminds me of the guy I saw on TV who had an electric Citroen 2CV with a big propeller on the back. The wind spun the prop which was connected to a generator... Unfortunately, the idea never caught on.

[NickLappos]

Buy it, Dave. At least its not one of those silly coaxial synchropter food processor blenders! ;)

[Dave_Jackson]

Nick, look back at the advantages of the early German helicopters, then look forward at the required attributes of future rotorcraft.

In both directions you will see 'eggbeaters' and the yoke will be those who don't look. http://www.unicopter.com/StickPoke.gif

[Robbo Jock]

Boss to his secretary:
"Do you know the difference between a Caesar Salad and a blow job?"
"No."
"Let's go to lunch!"



I'll get me coat....

[soupisgoodfood]

I think it will need to be a pretty windy day if you want to charge it in time to get home. :suspect:

I'm not sure it would even have the power to weight ratio to get off the ground. Electric RC helis are more powerful than nitro or gas helis, nowdays, but that's only true up to a certain size.

His idea sounds very dependant on battery or fuel cell technology. So unless he also has some breakthrough ideas there...

I'd at least want to see an electric heli hover, first. Then I'd wonder how he's going to deal with range, charging times, battery prices, etc..

Anyone can bung an electric motor into a heli, and then use it as a wind turbine, but getting those other little details sorted out is quite something else entirely.

[Graviman]

Hmmm, without a lot more info i would'nay touch it!

Nothing on the web, no design plans, no proof of concept, no demo of prior experience. As a recreational concept it is doable, but then so is a kite!

I would want to see something like a business plan, so that i knew roughly when to expect a return. Engineering is a tough game, and you need to be extremely serious to take a blank sheet of paper to production. Most of the so called "products" are little more than fun R&D projects. I'll be starting one myself (when my 2nd degree gives me time), but i'm smart enough to admit that it is only a design study.

Electric helicopters are feasible for very short duration. To beat a piston engine you need the motor to exceed 1kW/kg - figure on 10kW/kg for a gas turbine. A fuel tanks weight of batteries would give you a few recreational minutes, but little more. I haven't done the design calcs, but compare the downwash velocity to the average wind speed. Remember that power is proportional to speed cubed, and that the machine is at best about 50% efficient. This gives you an idea of charge times. The only investment to consider is time and effort...

Mart

[Dave_Jackson]

Well there has to be something better than oil based fuels. Just look at the number of fuel tanks that this helicopter has.

http://www.unicopter.com/Temporary/FuelTank.gif

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

[Graviman]

Say ain't yawl never heard o' the gravity powered helicopter?

Once the counterweight is wound up it'll go for hours. In fact, i'm going to start a scam/scheme and am looking for investors that are easilly wound up.. :E

Mart

[Dave_Jackson]

Mart, you and soupisgoodfood went serious on this 'tongue in cheek' thread, so I will join you.


Seriously consider the following in respect to perhaps the first piloted electric helicopter.

The intermeshing configuration (K-max) probably represents the best lift-to-power ratio of the current rotorcraft configurations.
soupisgoodfood mentioned that "Electric RC helis are more powerful than nitro or gas helis, nowdays, but that's only true up to a certain size."
The intermeshing SynchroLite was designed to comply with the lightest category that I know of; the FAA part 103 (115 kg. empty weight).
The reality of 'Ball-worm & Wheel gears' will offer the intermeshing configuration a single, compact, lightweight, and efficient, (3-gear only) transmission.Could there be a better rotorcraft platform in which to insert the precursors of the coming explosion in electric motor and battery technology?

Dave

[Graviman]

Dave,

OK, so we are thinking first "proof of concept" flight here, where only hover is a consideration? You have to set this against a backdrop of my not seeing any benefit in electric drive in helicopters, with existing electric powertrain technology.

I was never sure how the arguement about hover power settled itself. I remember that the S92 tail rotor consumed only about 5% engine power in a hover. The arguement against counterrotators was always hub drag, which clearly isn't an issue in hover. Clearly for high speed flight counterrotation is a given. Do you know the KMax kW/kg payload figure, for comparison against a similar size conventional?

The problem with transmission mass only really begins to present itself at larger machine weights. This is a direct result of larger diam disks needing lower RRPM hence higher torque for the same power. This is why the R22 gets away with an elastic band, while the MIL26 cooling duct is the same diam as it's gas turbines. This is actually an arguement in favour of twin rotors for cargo BTW.

There is always the arguement that the method most likely to ensure a result is to take a known machine, like say the S300 or R22, and convert it for electric powertrain. The orginal Gloster E38/29 designed to prove Frank Whittle's turbine was originally designed as a canard. Despite the paper advantages a tailplane machine was chosen to sensibly reduce the design risks - no need to stub your toe...

Mart

[soupisgoodfood]

My point was that it seems putting the cart before the horse. If I had an interest in electric full-size helis, then I'd be investing in battery and fuel cell technology, not electric heli projects. I already know that electric motors are more powerful, reliable, and mechanicly simpler to fit into a heli.

Also, I think I'll change my stance and say that an electric heli could fly today. But you're still left with the range and charging problem.

If I was serious, I'd invest in fuel cells. If i was tongue in cheek, I'd install a golf cart motor into an R22 and park it's ass over a slope-soaring clift and use it to power the house. Just don't be suprised if you see an R22 fly past your window as you wonder why the TV has stopped working :E

[rotorboater]

Obiviously range is the problem but you can always get a range extender, for every extra sector you fly you will need just to buy an extra one, B&Q sell them in 100 metre rolls and you can plug quite a few together to get to where you want to go, lot of work to untangle & wind up though at the end of a day!;)

[Dave_Jackson]

Mart,
I remember that the S92 tail rotor consumed only about 5% engine power in a hover. http://www.unicopter.com/Bull****.gif Empty in ground effect? :)

Here is a short answer as to why recent proposals for future rotorcraft have not included a tail rotor.
http://www.unicopter.com/B329.html#Tail_Rotor


soupisgoodfood,
If I had an interest in electric full-size helis, then I'd be investing in battery and fuel cell technology, not electric heli projects.

OK, but thousands of companies and tens of thousands of engineers are going to be advancing electric vehicle technology. The small rotorcraft industry must spend its limited engineering resources developing items that are exclusive to the domain of rotorcraft.

Then, in a few years, rotorcraft manufactures will be able to buy the advanced motors and batteries, and combine them with their contributions to advanced rotorcraft.

Dave

[Graviman]

Here is a short answer as to why recent proposals for future rotorcraft have not included a tail rotor...

Good point well made. ~10% power loss, and possibly ~20% payload reduction, it is then.

Seriously though, regardless of planforms the only justification i can see to electric helicopters is recreational. It might provide a slightly cheaper way to get up there. Despite poor performance the machine would still require certification. If you were serious i would go with your distributed motor/rotor idea to keep development cost down (say 6 distributed around pilot). Vary individual RRPM for cyclic/collective, and make sure blade AOA (rel airflow) fixed to optimum by tip tabs (ie unconstrained pitch). This allows safe auto-autos in case you forgot to charge. :ooh:

BTW if you're smart put a gyro in the power electronics pitch/roll control system to make the thing flyable. Dihedral would provide additional pilot feel in directional flight, but not necessarily the stability (gyration being the main problem).

Mart

Edit: Thoughts about control system, but still don't think poor range performance is worth the development investment...

[soupisgoodfood]

Seriously though, regardless of planforms the only justification i can see to electric helicopters is recreational.

They may find a niche where reliability and response time is important and a long range and payload isn't required, such as aerial photography and observation etc.

Of course, there are already a lots of RC helis doing just that, so sitting the pilot in the aircraft, rather than standing comfortably on the ground doesn't seem like much of an advatage in most cases.

Maybe the FBI could use them for their black, silent helicopters! :}

[Graviman]

They may find a niche where reliability and response time is important and a long range and payload isn't required, such as aerial photography and observation etc.

Range would pretty much be limited to around the trailer used to take heli to location! Maybe since it would use a diesel tow engine you could think of it as a land/air diesel/electric hybrid! :}

Helis are just so power hungry that any battery range is impossible. I'm quietly dissappointed Dave just can't stick to the Independant root&tip control blade, since this has real technical merit (as long as retreating reverse flow is accepted for counterrotator helis). Improving heli efficiency in all flight regimes is the future...

Mart

[Dave_Jackson]

http://www.plettenberg-motoren.com/Motoren/370_40_H.gif
2.5 horsepower per pound :ok:

http://www.meinpapi.de/dieter/JAMO_0-33Wi10Abig.gif

[Graviman]

Dave,

Motor technology is not really the problem...

http://www.amsuper.com/products/motorsGenerators/104074509641.cfm

Don't forget this is low RPM direct drive so will not offer best power/weight.

The big headache is how to generate the electrical power.

Mart

[slowrotor]

Dave,
Do you have a better link for the motor shown above? I could not get any info from the link.
slowrotor

[Dave_Jackson]

Mart,
The big headache is how to generate the electrical power.

The good news is that the helicopter will be fly-by-wire.
The bad news is that the wire will be from the helicopter to the ground. :)


Slowrotor,

Information on this motor [Plettenberg ~ Inrunner ~ HP 370/40 Heli] is located here. http://www.plettenberg-motoren.com/UK/Motoren/Brushless/370_40h/Motor.htm

An electric motor for a manned helicopter will have to be a little closer to the ones that Mart mentioned. However, four or five Plettenberg ~ Predators, at 11KW each might do. :eek:
http://www.plettenberg-motoren.com/UK/Motoren/aussen/Predator/Motor.htm


Dave

[Rich Lee]

A better investment might be in batteries and fuel cells. The electric helicopter can be considered in the same light as razor. Give away the razor but charge handsomely for the blades.;)