I can't wait for electric/hybrid aircraft.

[Justiciar]

There are essentially two possible futures. In one, we now invest the finite resources we have in the best way we can to create a (lower) standard of living that is truly sustainable for the future. In the other, we continue to live out our orgy of consumption, deluding ourselves that science and engineering will make it all OK - until one day we wake up to find a denuded earth can no longer supply our gluttonous desires. Sadly, the first is, I suspect, politically not viable.

Hit the nail on the head, I would say, except that anything using finite resources is by definition unsustainable for the (long term) future. There is no way to supply a planet of 5 billion + people with natural resources for an indefinite period, no matter how good the recycling! We are faced with an inevitable exhaustion of natural resources at some point. That will probably be sooner rather than later in the case of oil, with some minerals and metals taking rather longer. It is a frightening thought and I suspect that in the future nations will war over resources to a huge extent and the future imbalance between rich and poor will grow rather than diminish. Current consumption of resources will be sustainable for as long as most of the world remains poor!

[FullWings]

...except that anything using finite resources is by definition unsustainable for the (long term) future

True, but that applies to everything. See: Entropy and Big bang to heat death.
Our problem is (will) be more along the lines of ever-expanding population making more demands on finite resources.

Even if we froze our technology where it is today, we can still deploy solar arrays which will provide all the energy we require, up to the output of Sol; see Dyson Sphere.

I don't think we are running out of fuel, in fact we are are near to an "age of plenty". There is enough oil/Uranium/Thorium to tide us over to the point where we have fusion power - and if not, the Sun will provide.

If current scientific thinking is correct, we don't have an ultimate "long term future", so we might as well enjoy the present!

[Justiciar]

Its not just fuel but every other resource and commodity. We have seen recently how development of the likes of China and India have a huge impact on the supply and therefore the price of raw materials. We may indeed ultimately crack the problem of workable fusion power, but there are many other issues. Don't forget that oil supplies a lot more than petrol! Whilst there are many more untapped reserves than peak oil predicted they are in increasingly inaccessible areas or involve stripping the landscape in a way which may become ecologically and environmentally unacceptable.

[jimjim1]

Another diesel

Anyone interested in non-avgas light aircaft power units might like to have a look at Deltahawk. There is a web site but when I put the URL in here it gets changed to something about "All Posters"!!! Guess, or google for yourself

Clean sheet of paper aviation diesel. First flight 2003, certification this year they say. To me it looks very nice.

Initially V4 180hp, 160, 200 to follow and larger V8 eventually.
Can be ordered for upright, inverted or vertical (helicopter) operation and with either direction of rotation.

- Two stroke piston port diesel - no inlet/ex valves
- Mechanical fuel pumps - no electrics/electronics at all
- Runs on Jet fuel, various conventional or bio diesels.
- Low fuel consumption
- Small, light, low frontal area (no valves sticking up from cylinder head).
- Runs at convenient speed for propellors so no reduction gears/belts.
- Water cooled - OK at half power in event of total loss of coolant
- Supercharged - full rated power to 15,000ft I seem to recall.
- Uses external air pump so no air/fuel in crankcase so conventional oil system.
- Has backup air pump so engine will run at reduced power in the event of one air pump failing.

Very well thought out I thought.

The basic configuration is very similar to that used for very large marine diesels (i.e. two stroke with air pump) so it is for sure a proven technology. These are used in supertankers and they only fit one.

Wärtsilä-Sulzer RTA96-C - Wikipedia, the free encyclopedia

I have no connection with Deltahawk and am not a customer, I just like the ideas used by them.

[AdamFrisch]

The future is getting closer by the day...

NASA claims its quiet one-person electric aircraft is real | DVICE

[AdamFrisch]

Sorry to dredge up old thread, but recent events calls for it as Bertrand Piccard and his Solar Impusle team successfully flew a solar powered aircraft not only longer in time than anyone else - 26hrs - but higher, as well.

BBC News - Solar-powered plane lands safely after 26-hour flight

My hat is off to all involved - great achievement and baby steps towards a bright future.

[BackPacker]

Yeah, it's a great achievement. However, have you seen the aircraft? It's far from being a practical, every day plane. In fact, my first thinking was: "What's the crosswind limit on this one?"

Anyway, AFAIK the main thinking is that aircraft like this are able to function as a fast replacement for satellite launching. For instance to provide instant telco facilities in a disaster area. Sounds fair to me.

(And to be honest, the Wright flyer didn't have much of a crosswind limit either...)

[chrisN]

This is closer, but for one person and one hour at present. Maybe in a few years, when the batteries written about in January come about, it will be closer still.

Front Electric Sustainer - Future of gliding

Chris N.

[chrisN]

Just came across this - Chinese to build elec powered Viva and/or Apis:

http://www.nytimes.com/2010/07/20/bu...avyuneec.html? _r=1&ref=

Chris N.

[AdamFrisch]

Loads of interesting things happening in the electric flight world in conjunction with Oshkosh. It really is picking up momentum and I think we'll see radical changes and shifts in the very near future. It could even be the case that by the time the dinosaurs get their thumbs out of their behinds and come around to making diesels and rigmaroling through certifications and STC's - or finding a replacement for 100LL - electric or hybrid has already taken over. I very much doubt there's another 10 years for them to screw around in. By then it'll be all over.

First things first:

FAA has now realized that electric aircraft are imminent on the market and have fasttracked a way to implement it into LSA certification. So expect this not to happen overnight, but at least happen quicker than previously anticipated.

Yuneec's E430 won the Lindbergh Electric Aircraft Price, the first year it's been given out by the EAA. Not only that, the Yuneec E430 is now up to 2-2,5hrs in endurance and is at the forefront of being the first certified electric LSA.

There's a very interesting audio interview with Clive Coote of Yuneec where he talks about the systems and the aircrafts future here:

AVweb Interviews Yuneec International's Clive Coote

Pipstrel has released their plans to make and market a 4-seat, 200kt hybrid aircraft and going after the Corvallis market:

Pipistrel Four-Seater: Efficiency And Speed

Sikorsky showed their electric 300C helicopter. Although it can only fly for 15 minutes at this time, it's an interesting step. Imagine a flight school with an electric helicopter with exchangeable batteries: the price of training could be slashed:

Sikorsky Firely: An Electric Helicopter

Electric Cessna 172? It's in the works. And sanctioned by Cessna themselves, not some third party:

Bye Energy, Cessna Team On Electric 172

And the ultimate sign that electric is the future is to have the biggest visionary in aircraft construction and concept joining the camp - Burt Rutan:

Rutan Dreams Of Electric Flight

I know I sound like an evangelist, but electric could really get rid of pretty much every single problem and compromise we've had to live with in aviation for the last 100 years. It really is the second coming of Christ if the energy storage can just be solved. And it will be. That's the last obstacle.

[AdamFrisch]

Sonex, who were an early convert to electrics and has had a prototype in the works for donkey's years have finally test flown it.

YouTube - E-Flight Electric Powered Waiex N270DC First Flight!

[SNS3Guppy]

Just below is a thread about a C152 engine quitting because of either a rich cut or carb ice, depending on who's answering.

It was neither, actually.

[AdamFrisch]

Now Pipistrel announced their new Panthera - what a looker! It will be delivered in three different versions:

IO-390
Hybrid
All Electric

Overview

It's nice to see more and more mainstream implications getting off the ground. Hybrid solution is a great way to not only bridge the gap to all electric, but get additional benefits like hot and high operations or takeoffs on high density alts where both systems can provide extra safety for a take
off, etc.

I'm even more convinced than I ever was that the prime mover, the motor of all future aircraft will be electric. Anything else is foolish. How we power that is up for debate, but that it will propel that's for certain.

[FlyingStone]

Did you actually see the specs for electric Panthera?

215 NM range, 200kg useful payload, 118 kts cruise. Many non-certified (the certified version is planned for later, though I doubt EASA will certify electric aircraft in CS-23) two-seat Rotax-powered aircraft offer much greater performance and the fuel flow and subsequent price isn't as eye-watering as it will be Panthera's price (I believe Pipistrel representatitve quoted some 250 k€ for non-certified version at this year's Aero).

On the other side, I believe the IO390-powered version could be a success, comparing it to DA40/50/SR20 due to much more sleek aerodynamics (retractable gear helps), the payload with full fuel is actually quite large (345 kg) and if they'll certifiy for FIKI, it could become a solid IFR-touring platform. But only time will show

[BackPacker]

Hybrid

Can somebody enlighten me? What's the point of a hybrid aircraft?

I can see the point of a hybrid car more or less. You can charge the batteries with brake energy which would otherwise go to waste, and you need a less powerful engine since a car normally needs only about 20-30% of its power to maintain highway speeds. The rest is for overtaking and showing off. A smaller engine leads to lower friction/pumping losses etc., so uses less fuel.

But an aircraft engine essentially runs at about 70% for most of the time it's running. And even in the descent most engines still supply 30-50% power. So it's not like you can regenerate brake energy, or run the engine at a few extra % in the cruise, so that you have battery power available to crawl along in a traffic jam. So why would you take a big battery and a big generator/electric motor with you into the sky?

[FullWings]

Can somebody enlighten me? What's the point of a hybrid aircraft?

I don't do enlightenment but one reason is that you can have a smaller/lighter/more efficient powerplant which gets an 'assist' from the motor/battery for takeoff, go-around or any other critical stage of flight. Your engine could be max. rated to 60-70% of what you need in those circumstances, the rest coming from the energy store when you need it. There is also the advantage of having two separate (but not quite independent) motive sources should one fail, e.g. through lack of fuel, ignition, etc.

It would also be possible to charge the batteries with, say, a set of solar panels or a wind turbine next to your hangar. Free energy! (Well, not quite but you can see the point.)

You can also recover energy that would have gone to waste, e.g. idling at the holding point or in a steep descent to get rid of height. Bit like KERS in F1.

[IanPZ]

I find it hard to believe you would get much energy recovery, given that even in hybrid cars the recovery rate is miniscule (6-7% at best). However, hybrid is becoming very popular in boats because of the flat torque curve of an electric motor. That means that a smaller engine can run at maximum performance/fuel efficiency rate, and that can be converted extremely easily to useful power.

I assume propellers share a certain level of physics with boat propellers, which are being redesigned to take maximum advantage of high torque engines

Any thoughts, anyone?

[AdamFrisch]

Hybrid actually makes a lot of sense for aircraft. As you yourself mentioned, you're carrying around a heavy cast metal thing for 100% power output when you in fact only use 70% of the power for 99% of your flight. So you lug around all that dead weight just to be able to provide you with enough power for takeoff that you don't use after that.

Wouldn't it be better if you could have a smaller APU that could provide the cruise powering, and leave takeoff to a much more efficient electric motor?
It could be a turbine APU, like the passenger jets have - even more weight savings. And say goodbye to the hassles of 100LL at the same time.

Also, there is regenerative opportunities in aviation, although perhaps for smaller spamcans maybe less so.

The flat power/torque curve of electric motors means you can get rid of the complexities of constant speed props and tons of other equipment that todays aircraft are saddled with. Starters, generators etc. The weight savings are huge.

[FlyingStone]

Well, first of all, I don't believe constant-speed props or piston engines, used in today's aircraft are complex systems - perhaps they were 50-60 years ago, when they were developed, but not in 2011. Besides, I believe electric engine efficiency, just as in piston engines, is achieved if they are run at constant speed - so you need some kind of speed control in both cases.

The weight saving really made me smile According to Shell, the typical energy density of 100LL fuel is 44 MJ/kg, while the current Lithium-ion batteries in production don't reach even 1 MJ/kg. So basically, for the same weight of fuel, you get 44 times more energy with using 100LL. And on the plus side, when you burn the fuel, the weight of the aircraft decreases, so you need less power for same speed, reducing the fuel flow and thus increasing efficiency. With electric power, you still need to carry batteries around (unless you get rid of them in-flight, but this wouldn't be neither pro-environment neither economic).

I know the weight saving in small aircraft aren't large. But think for example of a transport aircraft, which flies on a transatlantic route. If we assume the fuel usage is ~ 150.000 liters of Jet A-1 (I googled the data, but I think it's a good estimate), this turns out to 123 tons of fuel, which (if using energy density of 42,8 MJ/kg) turns out to approximate 5.260.000 MJ of energy, which you need for the flight. Again, if we say that current batteries have energy density of around 1 MJ/kg, that means 5.260.000 kg or 5260 tones. Seems to be rather exponential increase of weight, not decrease if my math is correct?

Another problem is the energy flow problem during charging/filling up the aircraft, which is basically the same as we see with hybrid/electric cars. While I don't have the numbers for fuel flow for gas trucks on airports or electric system of airports, I can provide you with a comparison based on home electric system and car fuel stations. Let's say we use 230V system with 20A fuses. If we run this to the limit, we get 4,6 kW electric power, which indeed means 4600 J/s or 16,6 MJ/h. Our local fuel pump has a diesel fuel flow of around 0,5 l/s (probably a little higher, but let's stay conservative). Fuel flow of 0,5 l/s means that we pump 1800 liters in an hour, which (with diesel fuel's energy density of 35,8 MJ/l), this turns out to 64.440 MJ/h, which basically means more than 3800 times higher energy flow than with typical home-based electrical charging.

PS: I am no expert on subject of electricity, but I think this rough numbers are quite accurate for objective comparison.

[AdamFrisch]

There's a fatal flaw in your calculus: only 20-30% of the energy in fuel turns into shaft horsepowers, whereas electric motors have 90% efficiency.

But there is no argument that fossil fuel contains more W/kg than batteries at present. That's for certain. However on the other side of the spectrum, there is also no argument that electric motors can produce more W/kg than any other prime mover. They can't be beat, not even by turbines.

So by getting rid of all the dead weight you're lugging around in the form of your combustion engine, taking into the account that it's also just 30% efficient, the gap is closer. A 200lbs Lycoming could be replaced by a 20lbs brushless with the same output. That's 180lbs you can now use for something else, all things being equal. Like a battery or a hybrid APU.

It will take time before energy storage can match that of fossil fuels, but when you take into the considerations all the stuff you don't need anymore, then the gap you need to bridge is less.