Electraflyer Flies Trike, Motorglider On Battery Power

barnstorm2

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Nov 1, 2003
Messages
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Location
Cincinnati, Ohio
Aircraft
2-place Air Command CLT SxS (project), & Twinstarr Autogyro
Total Flight Time
750+hrs and climbing
http://www.avweb.com/news/snf/SunNFun2008_Electraflyer_TrikeMotorglider_BatteryPower_197632-1.html

For the sport flyer who enjoys local fun flights and $100 hamburgers, Electraflyer's new battery-powered airplane may be just right -- and with no fuel to burn, it can cut the cost of that hamburger down to about 60 cents. That's how much it costs to fully charge the lithium-polymer battery pack, says Randall Fishman, president of the Electraflyer Corp.

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The electric engine is mounted on an old Monnet motorglider that Fishman built from a kit, and the aircraft just this week earned its experimental airworthiness certificate. Fishman also is flying a battery-powered trike, which has about 55 hours on it. The battery pack has an endurance of about an hour and a half on the trike, and Fishman said he is still tweaking it on the airplane, but expects it will last about the same or a little longer.

The charging unit weighs about five pounds, he said, so it's easy to take it with you and recharge anywhere. "It's so quiet when you're flying, you can hear the wind going by, and there's no vibration," he told AVweb at Sun 'n Fun on Saturday. He's selling copies of the trike, and engine kits for homebuilders, from his Web site; a complete trike system runs about $17,000.



Fishman also said he is working on a two-seat model that would carry a larger electric motor.


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That's awesome! I have been wondering when someone would make electric flight available for the masses.
I have the smallest Makita lithium-ion drill/driver and have been repeatedly amazed at the amount of torque it packs into a light weight tool. I mean, it feels like a toy, but can drive 4" screws. I like it so much that I try to leave it in it's case for use in small spaces and use my old Milwaukee instead.

Anyway I'd really like to hear the thrust numbers coming off that electricity driven prop...Anyone want to pose a guess as to how long it will be until someone flys an electric gyro? I vote for my birthday next year--April 3 2009.
 
I would LOVE an electric gyro even if would be only short range.

"Gyros are draggy devices" so I think we will be the last to get electric.

Think how cool a silent super-maneuverable gyro would be to cut up the farm land with!

I would love it is someone or some chapter would buy the trike electric kit and put it on a bee frame...

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If we wanted to have an electric gyro, the first thing we'd have to do is to make a gyro that is as efficient as possible. What would we have to do to make a gyro that flies on 30hp, or better yet 20 hp? Bigger blades? wider chord? more pitch? less pitch? Obviously lighter, but what else? Partial wing would be a consideration... Probably a tractor to get a bigger, more efficient prop and a bit of streamlining. Any ideas?
 
John, it would have to be space age with a capital S and mucho bucks
 
Thats certain Tony. The batteries alone would cost as much as a 4 stroke Rotax.
 
Here’s the rub. According to Wikipedia, a lithium-polymer battery stores 130 to 200 watt-hours per kilogram, equal to 309 BTU/lb. using the higher value.

A pound of gasoline contains ~20,000 BTU/lb. of which only about 30% can be recovered as mechanical energy.

Even assuming the conversion efficiency of the energy stored in a battery can be converted to mechanical energy at an efficiency of 90%, the weight penalty of electricity is 21.6 times that of gasoline.

That 30 lb. of gasoline in your seat tank could be replaced by a lithium-polymer battery weighing 647 lb.

http://en.wikipedia.org/wiki/Lithium_polymer
 
I am not saying it would be at all practical, in fact it would likely be an utter waste of money, but 3 of those batteries in the wikipedia article in series would be 50 amp hours at 90 volts. If it could discharge at 15 c it would produce 67,500 watts Right? that would be enough to power 2 B&S E-teks or 2 Lemco motors to 15 or 20 hp each, possibly more, for a short time while the batteries are self destructing and the motors melt down. Might that not be enough to get an extreemly lightweight and efficient gyro off the ground for a short time?
 
Let’s see…50AH at 90 volts means 1 amp for 50 hours or 50 amps for 1 hour. That’s 4500 watt-hours (50A x 90V x 1 hour). With 746 watts per HP, that’s 6 HP-hours; 6 HP for 1 hour or 12 HP for a ½ hour; 24 HP for a ¼ hour. All at 100% efficiency; actual efficiency can be as high as 90%.

I didn’t read the article; how much does that 50AH, 90V battery weigh?
 
Although an expensive machine, it would be neat to have an electric gyro that even just takes you up to 500ft and then you glide back.
 
It doesn't say Chuck, but if we used (4) 22.2volt Thunderpower 9 amp hour lithium polymer batteries in series, and we packed them 9 deep for capacity, we'd have 88.8v and 81 amp hours at 106 pounds. They claim to put out 20c continuous and 50c peak (!)
I'm completely ignoring the difficulty of having them charge and discharge evenly.
That seems like it would get us into the ballpark for enough energy to break ground.

The batteries would only cost $21,600 but I think we could get a volume discount ;)

2 Perm PM 132 motors are $1000 each and will put out a claimed peak of 34 hp at 72volts and about 350 amps for a few minutes. They weigh 25 lbs a piece. Their continuous rating is 110 amps. Claimed peak efficiency at 72v is 88.6%

That would get about 35 hp for 15 min. at the claimed peak effeciency.

Motor+batt weight is 155 lbs plus PSRU.

I honestly think it could get off the ground if there were someone who really wanted to be in the record books for the first electric gyro. The only record that can't be beat is the record of being the first...
 
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There was a company doing business as Orlando Helicopter that played around with an electric helicopter a number of years ago. I think they managed to hover something based on the Sikorski S-51 with nothing more than ordinary lead-acid batteries in ground effect.

They were at one time offering a kit based on S-51 dynamic components and powered by a souped up GM automobile engine.

I dropped Dr. Bensen off at their place a couple of times and they always transported him back to my place. I think he was trying to work out an improved control system for helicopters based on force feedback. It was a big secret and I never tried to dig it out.
 
What can be done to make a gyro more efficient?
 
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In a gyro, we’re pretty much stuck with the blade tips going 300 or 400 MPH while the rest of the machine is hardly moving. That eats some power that can’t easily be reduced.

However, the real poison pill comes from the typical open airframe or the chopped off in the back cabin. I’m not convinced that a 2-place SBS can ever have drag as low as a tractor, even though the tractor has to fly through its own headwind. The problem is maintaining attached flow after the widest part of the cabin to the propeller.

I calculated the attached plot a number of years ago and it demonstrates just what a power hog an open frame can be. Pilots would be shocked at much proper streamlining could reduce power consumption.
 

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