Electric Powered Flight

[riverduk]

Hey All,

 

this is a spin off from another thread that I have been stirring the pot in (along with others)

 

Any how, just wondering how much interest there is here in Australia regarding Electric Powered Flight, here is a link to a US site:

 

ElectraFlyer.com - Home of the ElectraFlyer - Electric Aircraft Corporation I am sure there are others out there so lets get the ball rolling, interested in any thoughts, comments etc,

 

Cheers, Da Duk

 

 

[facthunter]

Electric Power.

 

Nice and silent. Wouldn't that be lovely. Be able to hear the airframe creaking. It's gotta be an exciting possibility. Nev

 

 

[Vision325]

Hi De Duk

 

I was lucky enough to go to Oshkosh this year and was specifically interested in

 

electric flight. I attended the electric flight symposium there.

 

It was a great listening to a lot of big hitters explaining their views and where their company's were at in regards to producing the technology and hardware required

 

for realistic electric flight.

 

If there was a consensus amongst the speakers it was that electric flight from the smallest aircraft to large passenger planes was inevitable.

 

They all agreed that the didn't see any plateauing of battery technology in the foreseeable future and that the problems of battery weight etc will be over come.

 

They felt that it was about five years until the first commercially acceptable two seat two hour flight trainer with a half hour charge time would be commercially available.

 

Burt Rutan is working on electric projects but wouldn't be drawn on specifics.

 

I learnt a lot at Oshkosh this year and the future looks very bright for electric

 

aircraft.

 

Stephen

 

 

[riverduk]

Nice and silent. Wouldn't that be lovely. Be able to hear the airframe creaking. It's gotta be an exciting possibility. Nev

Hey Nev,

it would certainly put you more in tune with your aircraft, then again it might stop you flying altogether eh?

 

Stephen, did you happen to get any web sites or other info that might spark some interest here?

 

cheers, Da Duk

 

 

[Vision325]

Powered Electric Flight

 

The web sites that are around are very limited in detail.

 

This is a link to the main speakers

 

The Future of Electric Flight - Symposium

 

Even Yuneec who are one of the most advanced hard ware makers said they wouldn't be releasing their motors until next year. Any way its really all about the battery densities . I think at the moment that the available LiPo batteries supply 0.25kw/hr per kg and they realistically need to be 2.35kw/hr per kg to match existing Ga internal combustion engines.

 

Chet Fuller – President, GE Aviation Commercial Systems stated GE had developed a motor with integrated motor control that is 97% efficient. This means that batteries only have to contain approx half the usable energy to be equivalent to petroleum based fuels as internal combustion engines lose approx 50% of their efficiency due to heat loses etc .

 

Other problems are how to get the energy into the batteries in reasonable time say 30 mins.

 

Also developing batteries that don't lose their ability to hold a full charge.

 

I think from memory after 400 hrs flight time you need to replace LiPo batteries as they would only hold 70% of their original capacity.

 

I had the feeling all these speakers would love to have said more but were trying to get the jump on the technology so were all holding back.

 

With the amount of money poring into Battery technology it is just a matter of time before they become very common. I cant wait!

 

Stephen

 

 

[Modest Pilot]

There was a Chinese Motor Glider at Oshkosh this year that looked like a good concept. Powered by a 40kw system that cost $33,000 US. The LiPo battery cost $10,000. (good for about 1000hours of engine time or 700 cycles?) The guy at Sonex said that was a good price; the one they are developing looks like it will have a $15,000 price tag!

 

 

[riverduk]

thanks MP, just wondering is this the one you were talking about? see link below

 

cheers, Da Duk

 

Yuneec International 2008

 

 

[Guest ozzie]

http://www.psfradio.com/impodcast/2010/08/10/psf100810b.mp3

 

Disscussion on the electric symposium at Airventure.

 

 

[i_like_planes]

Incredible how far battery development has come in the last 5 years. I'm still holding my breath for some decent capacitors though. Then we'll be flying!

 

 

[Powerin]

I reckon fuel cells might be good for aircraft rather than batteries. A lot of development is needed yet, but direct methanol or ethanol (or even hydrogen) fuel cells would mean you just refuel instead of having to recharge batteries.

 

Fuel cell - Wikipedia, the free encyclopedia

 

 

[mechfx]

I reckon the Sapphire is a good candidate for electric power conversion. Fast, light and proven to fly well on 40kw.

 

 

[Vision325]

Powered Electric Flight

 

I agree about the sapphire being an excellent candidate to try out electric flight with.

 

Any body got one they would like to donate to experiment with.

 

Another avenue that is fast advancing to larger and larger electric flight

 

HobbyKing Online R/C Hobby Store : Turnigy CA120-70 Brushless Outrunner (100cc eq)

 

It is only a matter of time before these guys start to think of the manned flight

 

market.

 

In regards to fuel cells they suffer from inefficiency problems at the moment but they

 

look promising. I believe there are fuel cell being developed that can use petroleum based fuels also.

 

At Oshkosh Flight Designs had an interesting concept where they had from memory a Rotax 4 stroke with a electric motor mounted on top of it coupled by a belt drive.

 

During take off the electric motor and the rotax worked together to increase power.

 

Then in cruise the Rotax charged the small battery using the electric motor as a generator. This seemed to be a good stepping stone to full electric flight.

 

Flight Design - Light Sport Aircraft

 

Steve

 

 

[Spin]

I agree that we have exciting times ahead and that battery/fuel cell etc development is probably still in its infancy.

 

I worry a bit about the practicality of some of the products which are being put forward at the moment though. For example, the hybrid Rotax sounds fine, channelling the Prius and other automotive hybrids which are rapidly moving into the mainstream, however normal operation of an aircraft powerplant requires 100% power for perhaps 5 minutes - more if you're climbing to a cross country type altitude, followed by a few hours at 75% or so in the cruise and then a relatively short low power decent. That doesn't leave much excess power for pulling what is effectively a great lump of a generator and heavy batteries around. Looks to me you're going to have to run the Rotax flat out in the cruise to charge the batteries, or otherwise specify an oversized engine to allow you to cruise at say 55% power whilst using the other 20% to run the generator.

 

Cars have a very different energy consumption profile, full power is typically only used in an overtaking situation, whereas cruise uses only a small percentage of available power - something like 8/9kW to run an efficient small car on a level road at 100km/h I believe, leaving plenty to spare for generator duties. There is also the opportunity for power regeneration in a stop start urban scenario or on a down grade. Even then a hybrid battles to beat the energy consumption of a small turbo diesel, thanks to the inherent inefficiency of converting fuel into stored electricity and then again into power via an electric motor.

 

 

[Vision325]

You will have to excuse my memory of Flight Designs explanation of their hybrid concept engine but the figures they put forward required to charge the batteries was something like %5 extra in cruise.

 

This engine has been built and was on display so their figures weren't only theoretical so it may be interesting.

 

Their reasoning was that they would save some weight by the fact that they would require a smaller hp engine with the extra hp coming from the electric motor at peak power settings.

 

The weight gain was quite reasonable as there was no need for large batteries due to the short duration of the electric assistance.

 

I hope this makes things clearer.

 

Their explanation made a lot more sense when I was their. My brain got fried with 7 days 12 hours a day racing from one exhibit/forum to the next.

 

Before Oshkosh I was skeptical about hybrids but I have a bit better understanding of how they could fill a gap while battery technology improves.

 

Time will tell.

 

 

[Spin]

Thanks for that, it does make it clearer - all very interesting. Roll on the day when I can have my own fuel cell generating electricity in the back garden, no o/h lines - plug the car in to top up the charge, same for the electric RV12 sitting on a trailer in the shed....., bugger, coffee is a fraction cold by now:laugh:

 

 

[Guest ozzie]

there is a real shame to all of this. we could have had good efficient batteries ect back by the mid 50's. All thru the midwest USA before the elec grid became available everyone used wind generators recharging battery banks to run houses and farms. worked quite well. Then along came the power companies stringing up powerlines and convincing people that it was much easier and economcal to just run a line to their property, and i suppose it was, those that resisted and wanted to run on windpower found that mysteriously their windmills fell over and the battery sheds caught on fire so slowly every one switched over to the grid. Now if that did not happen and it all went the other way we would now have the battery knowledge already and the methods to recharge them. Big biz sometimes works against us.

 

 

[Warmbrak]

These guys claim that they may have a solution ready for flight testing next year to re-engine a Cessna 172: Images

 

While it is interesting to see new aircraft being developed with lighter airframes to accommodate existing technology (such as Yuneec), I feel the real breakthrough would be conversion of existing aircraft to e-power.

 

 

[Guest ozzie]

Converting to electric has been happening for a few years now in the car area. A company in melbourne specalises in converting new Hyundis for about 25 grand or so. they will also do a number on your current pride and joy. a lot of interest in the rodding area for hybrides as well. The Isle of Mann TT has a race for electric bikes 160mph plus. So aircraft conversions are mainly just paperwork to make them legal. i think a Jabba conversion would improve it as a trainer no end.

 

 

[Gnarly Gnu]

Unfortunately electricity prices in Australia are starting to spiral out of control. At work I just received a notice that my power is going up to 23 - 26 cents kWh (winter / summer) and that's before the proposed Greenie tax that Labor wants to bring in. And for some bizarre reason the more I use the more expensive it gets. This is outrageous when you consider in most US states they are paying 10 to 12 cents. By the time the battery technology becomes viable for flight I wonder if the recharging costs will still be.

 

 

[riverduk]

Hey Gnarly,

 

Solar panels etc will help keep the bills down, perhaps even built into the wings of fixed wing aircraft, don't know how I'm gonna fit them on the Black Duk (Trike) though i_dunno

 

Cheers, Da Duk

 

 

[Mick]

I have some mates that are working with some pretty large electric scale models.

 

It seems that motor size and battery capacity are fast becoming unlimited if you are prepared to throw enough $$$ at it.

 

One of the limiting factors at this stage for a lot of batteries is recharge capacity, ie how big a current you can put into them which determines how long they take to charge.

 

This is particularly limiting with the Li-Po batteries that have such impressive outputs for their size and weights.

 

For example I have one small model that flies for about 10 minutes on a charge but the Li-Po battery takes over an hour to charge. Translate that to an hours flight in a full size and the charge time would be ?????????

 

Makes that 20 minute fuel stop now on a trip seem pretty convenient........

 

My mates are experimenting with some new types of battery that are slightly heavier and more bulky than the popular Li-Po's but give an equivalent flight time of around 9 minutes. The real plus though is that these new batteries can be re-charged in under 10 minutes. Another advantage is that unlike Li-Po's they can be left in the model while being charged.

 

I love my IC engines but the development of electrics has alot of appeal too.

 

Cheers

 

Mick

 

 

[Vev]

I also went along to Oshkosh and sat in on almost all of the electric workshops and discussions .. also met and spoke with all of the manufactures about their products.

 

The Yuneec guys were much more advanced in terms of a commercial release and their products look quite good. They had a 40kw motor mounted on a wall stand and I got to have a go at playing with it through the power and speed range .. the most interesting thing was how quiet and smooth it is.

 

Without exception all of the manufactures are waiting for the next step in battery technology .. most seem to think that Li -Air will be the next gen to provide the energy density they need. The problem is the cycle capacity is only around 3 or 4 cycles compared to 1500-3000 with Li-Po. I think the technology is already here but they need an engineering solution to sort out the cycle performance.

 

Never the less, the whole programme is real and alive using Li-Po and they are making great strides .. if I was a betting man I would say we will see a real commercial solution in the next 5 years that will meet the reliability and durability we will need for avaiation.

 

Very exciting times to come.

 

Cheers

 

Jack

 

 

[eightyknots]

No question which way the graphs are headed. Avgas/ULP going up and electricity/batteries down. It is only a question of time.

...yes, except the weight and power.

 

I don't think a Rotax 912 engine & full fuel tanks will be replaced by an electric motor & batteries of similar power and/or endurance for at least a decade.