An electric plane that cruises silently at 70 mph and costs just 70 cents to charge

[madokie]

http://www.popsci.com/military-aviation-amp-space/article/2008-12/silent-electric-plane

A Silent Electric Plane

By Amanda Schupak Posted 12.04.2008 at 12:54 pm 12 Comments



Happy Landings : The builder says his goal was a noiseless plane that would fly as smoothly as a magic carpet. John B. CarnettIn August, at the Experimental Aircraft Association (EAA) AirVenture show in Oshkosh, Wisconsin, Randall Fishman’s ElectraFlyer-C made a virtually silent pass over the audience at a mere 200 feet. What they were seeing (but not hearing) might be the world’s first fully electric-powered airplane—representing, said one EAA official, “a groundbreaking technology that would be aviation’s first true alternative to a fossil-fuel engine.”

Fishman, a retired jeweler from New Jersey, has been flying planes and gliders for 30 years. In the mid-1990s, he put together a motorized glider kit, but it was noisy and undependable. It sat in storage until two years ago, when he replaced its gas engine with an 18-horsepower electric motor he and a colleague designed to minimize noise and vibration. He then raised the plane body eight inches off the ground to accommodate a 45-inch propeller, increasing the prop’s thrust by more than half. He also designed battery packs to hold two 75-volt lithium-ion-polymer batteries, which can juice up in midair and propel the plane at 70 miles an hour for 90 minutes on a single charge.

Now Fishman is taking his creation to the public. He sells kits on his Web site (electraflyer.com) that include the batteries and electrical propulsion components. By mid-2010, he plans to offer ready-to-fly electric two-seat planes.

[TomInTib]

1. Now you've gone and done it.

I must have one of those. How cool would that be over SF Bay? Fly up around Mt Tam, out to Wine Country.

[madokie]

21. Make one a little bigger with two seats and a little more battery,

Load the misses up and an afternoon of fun to be had.

[thunder rising]

2. and the payload is probably 1 very skinny person.

[madokie]

5. I think its more for whats possible,

of whats to come. I'm impressed that it can fly for 90 minutes on less than a bux for recharging.

[thunder rising]

10. I can appreciate the effort and thought, the physics don't play out.

It's a great hobby plane. There are plenty of such things. 90 minutes at < 70 m/h is nothing.

[madokie]

11. Mostly what this does is prove its possible

or thats what I get from this article anyway. Its a first step to electrical powered aircraft, I like it.

[thunder rising]

14. This is no leap ... man powered aircraft have been flown.

[ddeclue]

16. VERY slowly in ground effect with people running along side

This is far better than that.

Doug D.

[thunder rising]

22. That must say something about ground effect ... FYI

I'm a pilot nearly ATP (which I'm sure you know is more of an award than a requirement to fly big planes full of people)

[RedCappedBandit]

3. want

[HeeBGBz]

4. Won't that be fun?

People buzzin around like bees

[Roon]

6. Awww, what wonderful birdies!!!

Are they all yours?

[ddeclue]

7. Way cool!!!!

I would add the following:

Much more reliable than a gas engine - much simpler, eliminates vacuum pump and alternator accessory issues for the instrument panel (hey it's all battery driven). Also eliminates problems with carb deice, water contamination of fuel, excessive vibration fatiguing the airframe, hearing loss due to prolonged exposure, noice complaints from homeowners, etc.

Would probably be much simpler to do the pre-flight checks as well.

Fuel at 70 cents for 90 minutes flying is incredible considering the recent cost of av-gas as well. An average C172 or PA28 burns 8.5 gallons of av-gas an hour with costs having been into the 5 dollar range recently fuel was making flying all but unaffordable.

The only down side here is apparent range and possibly recharge time. (There may also be electrical interference issues between the motor and radios but this should be fixable). A C172 or PA28 will have 5+ hours of range at about 90 knots or about 450 knot range give or take. Here we are talking about a 90 knot range. (Without winds.) I'm wondering how much the batteries weigh and whether it would be possible to increase the battery capacity to increase the range.

Doug De Clue
Aerospace Engineer / Private Pilot

[ddeclue]

8. Having gone to the website...

this is just a motorized parasail design and I wouldn't characterize it as very aerodynamically efficient.

It ought to be possible to get far better performance in both speed and range by applying the electrical motor and battery to a monoplane glider design with enclosed cockpit.

[madokie]

9. Where are you getting that info

I'm not finding where its said to be a motorized parasail. Help me out here

[ddeclue]

12. Electraflyer.com mentioned in the article

shows a picture of the "plane" - technically a part 103 ultralight, not a true airplane (there are weight and speed limits on ultralights but technically they do not require a pilot's license).

The picture makes it obvious that the wing is like a parasail type wing, not something you would see in most real airplanes with high aspect ratio straight wings with a main spar, flaps and ailerons etc.

This ultralight is steered by shifting body weight/moving the control bar just like a hang glider.

The power drive and batteries could be adapted to do a much more spectacular job on a high performance glider airframe and you could also increase the battery weight substantially if this were done as an experimental aircraft instead of ultralight.

Doug D.

[madokie]

17. but I'm seeing a small one seat plane

I see the paraglider too but this article is about the electric powered plane, is it not?

[ddeclue]

18. I only saw the paraglider and read that article..maybe I missed it..

clearly there are two flavors.

Doug D.

[madokie]

20. clearly

no kidding :hi:

[TahitiNut]

13. That's only one of the implementations. See this fixed-wing, enclosed cockpit design ...

http://www.flickr.com/photos/27224985@N07/sets/72157605355156982/

[ddeclue]

15. Ahhhh much better!

I would want something that would be considered an experimental airplane not an ultralight so I would be interested in additional battery capacity and perhaps a more powerful motor.

The aerodynamics are far better in the above picture but they could be better still if the wing and fuselage blended better. Would also do better with a Rutan style pusher design with the elevator forward of the CG so that you had lift from the elevator instead of negative lift which has to be made up for by additional wing lift (and hence additional induced drag). On the other hand I don't like canard designs aesthetically.

I wonder if a ducted fan design with the motor and prop embedded in the rear of the air frame and additional battery up front might not offer cleaner aerodynamics and better propeller efficiancy???

One other point - I'm not a fan of the tail dragger design as it is prone to ground loop but I guess it saves a lot of weight and helps reduce drag without needing retractable gear. It also looks like it has outrigger wheels like some gliders have to help keep it stable on landing and takeoff.

How much does the enclosed cockpit design cost?

Also how long does it take to recharge the batteries?

How many charge cycles can you get out of the battery pack?

[madokie]

19. 5 to 6 hours for recharge and 800 to a 1000 cycles

partly due to not having to stress the batteries much.