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350 HP No pistons!

Think it's more likely to be a lead in to a hybrid aircraft.

The weight savings would easily offset the installation of a small generator, easily fueled by 89 octane fuel. Gal/hour would be excellent... So, with the bladder being the lmiting factor, no need to carry 40-50 gal of fuel. Drop it to 10-20 gal tanks and more weight saved.

Overall, a huge reduction in operating/maintenance costs. Think it could be a great boost to GA.
 
MercFE said:
Think it's more likely to be a lead in to a hybrid aircraft.

The weight savings would easily offset the installation of a small generator, easily fueled by 89 octane fuel. Gal/hour would be excellent... So, with the bladder being the lmiting factor, no need to carry 40-50 gal of fuel. Drop it to 10-20 gal tanks and more weight saved.

Overall, a huge reduction in operating/maintenance costs. Think it could be a great boost to GA.
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A series hybrid may be the way to go, though weight and drag improvements will help in general. Anyway, take a gas/diesel sustainer engine sized for cruise power requirements and charging, plus a bit of margin. Hook that to a generator. Drive the prop(s) by electric motor, supplied by the generator and batteries with 10-15min of power. The stored electrical energy gives you the power boost for takeoff and initial climb, and they slowly get recharged during cruise for use in a go-around or engine out.

By this approach you can get insane takeoff power if needed (think near-VTOL performance, especially with a pair of folding props), and since the engine isn't directly driving the prop, you can run it at optimal RPM and you can use pretty much any engine you want, without worrying about torsional vibration or reduction gearboxes. It's also easier to integrate into the airframe and you can use an optimal cooling system (ducted radiators).
 
Hybrid systems work in cars because they recover energy from braking, and can use the electric motor to assist in acceleration, allowing a smaller gas motor which is more efficient in steady speed cruise. Neither of these situations exist in aircraft.

An airplane needs to make full power for hours on end, while a hybrid battery generally only contains minutes of energy. Your 89 octane generator still needs to be 180HP if you want to cruise as fast as your 180 HP Lycoming, and the fuel consumption of an engine like a Lycoming run LOP is really low for the power it produces. Most GA aircraft engines will already run happily on 91 octane, it's just that you can't get it at most airports.

You could get better takeoff performance in a plane with a hybrid system, but you aren't going to halve the fuel consumption, or even really reduce it at all. The gains that come would likely come from an optimized airframe with the new packaging that is possible.
 
You could probably fill the wings with Lithium batteries and still be light, maybe get a good few hours or more of flight time but who wants to sit overnight to charge the batteries on a Xcountry. The Tesla with charge 80% in ~ 20 minutes on 440 volts... But when will we see FBO's across the country that will have chargers... Maybe someday
 
Jordan1976 said:
An airplane needs to make full power for hours on end, while a hybrid battery generally only contains minutes of energy. Your 89 octane generator still needs to be 180HP if you want to cruise as fast as your 180 HP Lycoming, and the fuel consumption of an engine like a Lycoming run LOP is really low for the power it produces. Most GA aircraft engines will already run happily on 91 octane, it's just that you can't get it at most airports.
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Might get significant weight savings in the engine using a much smaller (cubic inch) higher reving, higher compression engine still producing cruise power. Think of say a 120hp turbo charged engine would produce same 9000 ft power as that 180hp lycoming does. Then add thin film PV to the wings to provide for recharging on the ground and a little extra power in the air.....
Engine quits and you have 15 min of full power to land. Put the engine in the tail, move the wing back, streamline the nose. I think I will start that mod right now. will only take a few hours I promise.

I do like the ideas, but still a long way to go before realistic for a cross country machine. Training aircraft that have 1 hr flight time with 30 min reserves is coming close to possible.
 
Remember the 5 1/4 floppy disc, now we have 512 GB card, who knew back then. Same with battery tec, I can't wait to see what the very near future brings us. :D
 
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[email protected] said:
Might get significant weight savings in the engine using a much smaller (cubic inch) higher reving, higher compression engine still producing cruise power. Think of say a 120hp turbo charged engine would produce same 9000 ft power as that 180hp lycoming does. Then add thin film PV to the wings to provide for recharging on the ground and a little extra power in the air.....
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RV-8 Wing Area = 116 sq ft
Max sunlight = 100 W/sq ft
Thin film solar panel efficiency = 20%
Power = 2.3kW

120 HP = 90KW

You'd only need to charge in the sun for 40 hours of direct, intense, equatorial sunlight in order to fly for an hour. In flight, each hour of flight only adds about 80 seconds to the flight, the same as about 8 ounces of fuel.

As for a small, turbo engine, why go through the whole electric conversion and back instead of a gearbox? If you have a small engine that is reliable enough for an airplane, then you have something special already.
 
FasGlas said:
You could probably fill the wings with Lithium batteries and still be light, maybe get a good few hours or more of flight time
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It takes almost 4,000 lbs of batteries to have the same range as 40 gallons (240 lbs) of fuel. The Tesla battery is 1,200 lbs for the same range as a 12.5 gallon tank in a car at 20 MPG.
 
Jordan1976 said:
As for a small, turbo engine, why go through the whole electric conversion and back instead of a gearbox? If you have a small engine that is reliable enough for an airplane, then you have something special already.
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If you run though the generator then out through a motor, there are some small losses in the conversion, but it allows you to recharge charge the batteries (for the times you need extra power). You also avoid having to do the whole gearbox development process, you don't have to deal with torsional resonance and vibration, the engine doesn't need to absorb propeller loads, packaging the engine and motor installation is easier (you don't need to put the engine right next to the prop or use a long, heavy, tricky-to-get-right driveshaft--heck, you can run more than one prop if you want) and potentially less draggy because you don't have a big blunt engine before or after your prop, with all the flow problems that entails. You also won't need to worry about throttle response; it either runs all-out or idles.

The advantage with the series hybrid concept is that your fuel engine need only be large enough for cruise power, instead of being sized to provide a lot of takeoff power. But that pretty much requires that a lot of effort be put into making a light, slick airframe, and that most likely means molded carbon fiber structure.

Again, think of the possibilities of an airplane with an electric "afterburner" mode that could put out 400+ horsepower for a couple of minutes. If there's anything that would make personal fixed-wing VTOL aircraft possible, it's this.
 
Jordan1976 said:
It takes almost 4,000 lbs of batteries to have the same range as 40 gallons (240 lbs) of fuel. The Tesla battery is 1,200 lbs for the same range as a 12.5 gallon tank in a car at 20 MPG.
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A Tesla will drive from LA to Vegas on one charge. It's about 400hp equivalent. I have a Ford electric truck that has NiMH batteries, 320 volts 100 ah, they weigh less then 800 lbs. Lithium batteries weigh a fraction of that. You could fill a hangar with 2 tons of Lithium batteries. Just pick up a new 12 v Lithium battery they sell for planes, weighs oz's.
 
A Tesla requires less than 30HP at cruise. An RV requires 100 to 120HP for Cruise. This would mean a range of maybe 60 miles for an RV on a Tesla battery pack.

The trick isn't power production for electric motors. Heck, trains, ships, even submarines are electric. The trick is energy storage, which is batteries. Yes, lithium battery technology provides much better energy density than lead acid, but still nowhere near that of gasoline or diesel.

Tim
 
bret said:
Remember the 5 1/4 floppy disc, now we have 512 GB card, who knew back then. Same with battery tec, I can't wait to see what the very near future brings us. :D
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Data storage (and computers in general) have been subject to Moore's Law for the last 50 years (i.e. a rough doubling in storage density or compute power every 18 months). I don't think that battery technology has been anywhere near the same trajectory.
 
And people say automotive engine installations are for people who prefer tinkering to flying. Granted, an automotive installation is a little more complex than a battery and an electric motor, but as a system i'd be surprised if working out the bugs will be any easier on an electric or hybrid installation than on an automotive installation.
 
True. I too think we will see more and more electric airplanes. But the road will not be easy.
 
My guess would be carbon nanotube hi pressure hydrogen storage to PEM fuel cells direct to electricity. At least for the airline size ships.
 
Jordan1976 said:
As for a small, turbo engine, why go through the whole electric conversion and back instead of a gearbox? If you have a small engine that is reliable enough for an airplane, then you have something special already.
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I think one main advantage would be that your engine does not have to be that reliable. If I had enough battery power to survive a failure of my fuel engine I would be just fine with the reliability of a modern car/motorcycle engine without modifications running at optimal rpm at all times. Wonder how much more weight such a hybrid concept would really have. You need some additional weight on batteries for 15 minutes of flight or so, the electric engine, electronics and the generator and save some weight on the fuel engine ( e.g. No magnetos, smaller higher rpm).

Now getting all this to work reliably would be a fun project even if it doesn't make sense .... .
 
FasGlas said:
A Tesla will drive from LA to Vegas on one charge. It's about 400hp equivalent. I have a Ford electric truck that has NiMH batteries, 320 volts 100 ah, they weigh less then 800 lbs. Lithium batteries weigh a fraction of that. You could fill a hangar with 2 tons of Lithium batteries. Just pick up a new 12 v Lithium battery they sell for planes, weighs oz's.
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At 1200lbs for a Tesla battery pack, you'd only need 3.33 Tesla P85 battery packs to reach 2 tons of batteries. That leaves a lot of room in that hangar. :)

The numbers are pretty clear: 1200lbs (electric) vs 75lbs (gas) for 250 miles of range.

We have quite a ways to go before we have viable electric planes with RV performance.
 
10,000 Farad Graphene SuperCapacitor

bret said:
This company has a 110 lb electric motor rated at 350 HP @ 2500 RPM direct drive! Now all we need is Testla to make batterys to fit into our fuel tanks and firewall!

http://phys.org/news/2015-04-world-record-electric-motor-aircraft.html
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Bret, This may be the missing piece to the puzzle.

http://www.marketwatch.com/story/su...0000-farad-graphene-supercapacitor-2015-05-06

Not the first to be touted as a "SuperCapacitor", may not be the last. Is it more than "vaporware"? Time will tell. Tesla is hoping to have their batteries down to $150/Kwh by 2020, this outfit is hoping to cut that by two thirds by the end of this year. They do not address weight in their press release. Caveat Emptor
 
Hybrid...

All you really need is time to make a decision and find a suitable place to land. Someone (I think Eurocopter) was looking into this for helicopters. Think only 1 minute of full power from a battery. Enough for 20-30 seconds of "ohh, $#!T, what just happened?" then get collective down to enter the auto, then another 20-30 seconds for a full powered landing.

Same for a F/W:

Enough power to keep prop spinning until you recognize it and pull power and establish best glide (because you always fly at an altitude to make a proper glide to a safe landing location, right?) then just enough power to correct for an imperfect emergency pattern (which you won't have because you regularly practice flameout approaches, right?).
 
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