# Finally an electric aeroplane

1. Oct 3, 2008

### mgb_phys

They call it the first Battery-Powered Plane (but thst's only because they don't know any better)

http://blog.wired.com/cars/2008/08/the-company-cla.html

70Mph, 2hour endurance and a 2hour 60cent recharge!
It's also silent, low vibration and of course pollution free.

Amazing - I want one (except I can't fly and have nowhere to put it!)

2. Oct 4, 2008

### Redbelly98

Staff Emeritus
Neat. I wonder how easy it is to change batteries? You have a 2nd battery on the recharger while you fly around. 2 hours later you land, exchange batteries, and off you go again!

3. Oct 4, 2008

### FredGarvin

I guess it was just a matter of time. It makes sense. The reliability goes way up. I would also redundancy would be much easier to design in. Very neat.

4. Oct 4, 2008

### dlgoff

http://electraflyer.com/" [Broken]

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5. Oct 4, 2008

### mgb_phys

Surprised the power/weight for batteries is good enough - it looks like the lightweight low speed prop is the real breakthrough.

I wonder if you could put a few m2 of solar panels on the wings and give the range a boost.

6. Oct 4, 2008

### Staff: Mentor

That calculation is relatively easy: A good solar panel can generate 140 w/m^2 at noon. The batteries on that plane hold 5.6 kWh and can power the plane for up to 2 hours (2.8 kW). If the wing area is 10 m^2 (it is probably less), in 2 hours, it would generate enough energy to keep the plane flying another hour.

This, of course, assumes the sun is high in the sky and doesn't take into account the weight of the panels or electronics, which would be substantial...

7. Oct 4, 2008

### mgb_phys

I thought (it's too early here for calculations) it was impractical because the solarplanes are ultra-light NASA carbon fibre things. So I was surprised that the battery on this worked.

Although - this is likely to be mainly used in areas with nice weather (SW USA). It might be worth having a m^2 of solar panels just to re-charge on the ground, so it's charged for the next days flying.

8. Oct 6, 2008

### charith

Hey,

Out of interest, how much does a small aircraft such as this normally cost?
And how much runway do these need to take off and land?

Thanks,
Charith

9. Oct 6, 2008

### Topher925

This the right question to ask. Electrical power trains can achieve much higher power to weight ratios than any internal combustion engine can. Designing an electric airplane that will perform is easy. Doing so at a practical cost isn't.

I would guess that this plane is going to be a lot more expensive than its gasoline powered counterpart.

As for take distance, I'd guess around 100-200 yards. Can't really tell just by looking at it.

10. Oct 6, 2008

### charith

Hmm, how much would a gasoline aircraft cost?

Also, they might be able to fix the cost of the lithium battery packs by using something such as this: http://en.wikipedia.org/wiki/EEStor

Its claimed to have a higher energy density and lasts much longer than the lithium packs used on this aircraft.

Do you guys believe this technology is actually real and viable anytime soon?

11. Oct 6, 2008

### mgb_phys

Cost is apparently $16-21k. I don't know how much an equivalent piston engined aircraft costs but in terms of SUVs that seems like a bargain! The recharge may only be 60c, but the battery pack is$6K and has a 1000 cycle life so \$6/flight in depreceation.
I suppose by the time you have worn out one pack some better technology might be available.

12. Oct 6, 2008

### Staff: Mentor

You mean the next night's flying. :rofl: Sorry, I couldn't resist

13. Oct 6, 2008

### Staff: Mentor

While that is true, it is incomplete. The energy density of the "fuel" is also pretty important and the energy density of batteries is almost two orders of magnitude below that of conventional fuel. And, range is a component of "performance". As such, making such an aircraft practical is not really a matter of cost, it is a matter of performance. Electric planes (with batteries) can come nowhere close to the performance of conventionall powered planes.

14. Oct 6, 2008

### Staff: Mentor

There isn't really any new technology here. It is most certainly real. But as I pointed out in my previous post, there is a serious and probably impenetrable performance barrier to viability. Battery powered electric planes will amost certainly never be anything more than a novelty.

Hydrogen fuel cell powered planes, however, stand a fighting chance of viability.

15. Oct 6, 2008

### mgb_phys

I suppose general aviation flying is itself a bit of a novelty. I'm very impressed that they made this work with a relatively conventional aircraft given the disadvantages of batteries.

Without a pilot your could triple the range ( the battery pack weighs about 80lbs) so the same airframe could be a 6-8 hour endurance RPV for 1/100 the cost of a predator.

16. Oct 6, 2008

### Topher925

Indeed. Battery technology does allow greater power to weight ratios but not necessarily greater energy to weight. In some applications it does and in other it doesn't.

This is not the first time someone has done this although the article says it is. People have been building electric planes for years now, especially ultralights.

http://www.airventure.org/2007/4wed25/sonex.html
http://www.treehugger.com/files/2008/01/first_conventio.php

17. Oct 6, 2008

### Staff: Mentor

Very true. When you're building something as a hobby, often you do it just to prove you can, not to meet a performance spec.
It would have very little in common with the Predator, so that doesn't really mean a whole lot. Also, a pilot isn't all that heavy of a flight control system. Taking him, his seat, and his instrument panel out doesn't mean saving 200 lb when you have to put back in a lot of electronics and controls to turn the plane into a UAV.

Last edited: Oct 6, 2008
18. Oct 6, 2008

### mgb_phys

There are a lot of less demanding UAV roles; LIDAR, power line surveys, forest fire wathc, animal research that would be nice to do with something that cost as much as a bit of lab kit instead of as much as a building!

I don't know if the FAA/CAA rules for UAVs are relaxed if you are in the middle of nowhere.

19. Oct 6, 2008

### charith

Oh, the technology I was referring to was the EEStore batteries, they claim to have an energy density 3 to 5 times greater than the Li-Ion batteries and offer almost unlimited charges before the battery pack dies off.

To be this seems like a dream battery for this sort of purpose and for transport.

I am referring to http://en.wikipedia.org/wiki/EEStor or just google up EEStor.

Does this technology seem possible to you guys?

20. Oct 6, 2008

### Staff: Mentor

Well, fair enough, and the military has dozens of other UAVs:
http://www.globalsecurity.org/intell/systems/uav.htm

I would think it might be worth considering a solar powered one for the high altitude-long endurance type.

Last edited: Oct 6, 2008