Traditional Homebuilts Suited to Electric

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Tiger Tim

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What, if any, traditional homebuilts might be suited to a conversion to electric power? This is in the spirit of taking a proven airframe so that a builder isn’t stuck concurrently developing two things. Using a known set of plans should get airplanes in the air sooner and power systems developed faster.

It seems to me that you would want an airplane that’s speedy on modest power and maybe a two seater converted to solo so that a lot of that useful load can be put to work carrying batteries. Would a Tailwind work well on electric power? How about a Sonerai II? Maybe a VariEze or a Mustang 2?

What do you guys think?
 

TFF

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You can’t carry the batteries. Not yet. All the electric planes on the market are essentially high performance motor gliders. They need the wing lift. Think Cub. Pipistrel has Cub span. super Cub weight. 250 lb of batteries gets 45 min of 75kt cruise. In away it’s kind of impressive. With the short wing fast planes mentioned, I bet that 250 lb battery would take off once and be dead at the crosswind turn. My guess is a Tailwind would need four of those batteries to take off and fly at cruise for 45 min and actually fly at Tailwind cruise speed of 150 kt. 1400 lb gross plane and 1000lb of batteries. 400 lb for airplane and people. Can’t see it better for the Mustang 2. Worse for the Sonerai. VariEZ might be the edge by 5%. Get it back to three batteries, you might be able to fly around a little at a reasonable gross for a few minutes.
 

Voidhawk9

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You need designs that can fly on very low power, essentially. That's why all the new electrics are so glider-like or have poor endurance. Most electrics take-off in what would be considered almost a fuel emergency for a conventionally powered aircraft!
 

BJC

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What, if any, traditional homebuilts might be suited to a conversion to electric power? This is in the spirit of taking a proven airframe so that a builder isn’t stuck concurrently developing two things. Using a known set of plans should get airplanes in the air sooner and power systems developed faster.

It seems to me that you would want an airplane that’s speedy on modest power and maybe a two seater converted to solo so that a lot of that useful load can be put to work carrying batteries. Would a Tailwind work well on electric power? How about a Sonerai II? Maybe a VariEze or a Mustang 2?

What do you guys think?
Of USA E-AB, a modified Waiex is the only one that much honest information is available on. See https://www.sonexaircraft.com/e-flight/ for info on their development work. Note the endurance and range. I would hope that practicable advances have been made since their work, but I doubt that those advances are ready for common usage in an airplane.

BTW, it is the only electric powered man-carrying airplane that I have seen fly.


BJC
 
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Aerowerx

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Solar augmentation??

Start with a electric self-launch sailplane, and cover the wings with solar cells to help keep the battery charged when in cruise.
 

Pops

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I think the SSSC with the first set of longer wings would be a good one for electric. With the 1835cc VW engine , I could hold level flight at 2000 rpm @ 53 mph. The idle rpm on a VW is about 950 rpm. At that time the EW was 450 lbs with 120 sq' of wing area.
 

BBerson

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The gross weight could be adjusted upward with batteries in the wings. (span loaded like water ballast)
 

BJC

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Great pick! Mine would be similar to a metal Electra Flyer ULS.
I’ve seen the electric powered Song, aka Electra Flyer, and it looks like a good set-up, considering the state of the art as of 5 years ago.

Some questions to anyone who has more up to date information.

Is the Electra Flyer ULS airframe (a Song) available as a kit in the USA?

The Electra Flyer web site has not been updated in three years. Are they still in business?

Has there been any independent verification of the Electra Flyer performance claims?


BJC
 

litespeed

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Some Australian designs might be suitable as well.

As a start would be the Sapphire by Scott Winton of World record holder fame from the Facet Opal

Sapphire


The Sapphire is a lovely little thing in the sub 300kg class. Add some more wing and should be great.



The Opal would be a real contender as it was very efficient as noted by its world records in time to climb even up to very high levels. Also endurance which was extreme. It never had a great deal of power either so could be expected to fly on little energy.
Note the Opal was a one off, but a modern version could easily be done and produced at a competitive price.
It holds still many records for FAI sub 300kg.

The Facet Opal holds / maintained the following highs and climb records for ultralight aircraft:

  • 3000 m in 6 minutes
  • 6000 m in 20.5 minutes
  • Altitude 10,300 m FAI class C1a / 0 (piston engine-powered aircraft under 300 kg)
Here are the specs- Note the 110kg fuel load that is a lot of batteries assuming the engine and controller still weighs as much as the original 40 hp.

  • Hull length: 3.2 m
  • Span: 6.6 m
  • Wing area: 10 m²
  • Wing depth: 1.6 m
  • Profile: NACA 66 (1) -212 mod. 12% thickness
  • Unladen mass: 110 kg
  • Fuel: max. 110 kg (estimated)
  • Max. Starting weight: 300-320 kg
  • Max. Surface load: ~ 30-32 kg / m²
  • Top speed: 280 km / h
  • Cruising speed: ~ 250 km / h
  • Consumption at 250 km / h: 9.2 l / h (6.9 kg / h)
  • Range: 3200-3500 km

Note it sips fuel at 250kmh only 9.2lt/hr, drop that down in speed and it would be a real frugal beast. Aslo at the heights he flew it would be making little power on a atmo engine.

It also has a lovely 10 metres of wing area for solar.

 
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litespeed

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It still amazes me the time to climb 3000m or roughly 10,000 ft in 6 mins.

It certainly climbs like a high speed elevator. Initial climb must be well above 2000ft/min.

A massive difference to other 40hp light machines.

All on a old school rotax air cooled 447

That would indicate, it can fly and climb on substantially less and still be a great thing. So I nominate the OPAL as the best of the breed for electric.

IF someone can beat it, please do and we all win as a sport.

The opal should also be reasonable to make price wise as well. It is just a wing with a pod for pilot and would be easy to do in Carbon with a carbon/kevlar cockpit.

The far lower cooling drag from going electric would make it even more slippery.

Unlike the mainly glider/motor glider style machines, this one has a very small footprint for hangers and trailers. Just prop it sideways on a trailer at a angle and good to go. So no need for folding or detachable wings.

Keep the nominations coming fellas.
 

GeneG

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Arkansas
I’ve seen the electric powered Song, aka Electra Flyer, and it looks like a good set-up, considering the state of the art as of 5 years ago.

Some questions to anyone who has more up to date information.

Is the Electra Flyer ULS airframe (a Song) available as a kit in the USA?

The Electra Flyer web site has not been updated in three years. Are they still in business?

Has there been any independent verification of the Electra Flyer performance claims?


BJC

I'm sorry but I have no information. In the video the designer indicates that they have the molds to produce them though.
 

13brv3

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I had never heard of the Opal, but what a neat concept. I'd love to see similar style planes as either part 103, or E-AB. It sure seemed to fly well for such a short aircraft. Pity it eventually cost the world an innovated designer.

I've considered aircraft for electric conversion, and one that keeps coming to mind is the Kolb FireStar II. It has a lot of wing, and was made for lower power. They can be purchased complete at pretty inexpensive prices as well.
Rusty
 
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