In development, electric-powered light aircraft

[Hobbes]

Sonex Aircraft Unveils Electrically-Powered Proof Of Concept SportPlane

From: http://www.aero-news.net/index.cfm?ContentBlockID=3ee41f10-02b3-4067-aace-fd579501c254&CFID=16116587&CFTOKEN=36096323

Plug and Play - And It's Good For The Environment

The crowd surrounded the small yellow Sonex plane at AeroShell Square, waiting for answers. Electric? Ethanol? What will Sonex Founder and President John Monnett would be announcing at Tuesday's press conference about his company's E-Flight Initiative?

Following company accolades by Tom Poberezny concerning the company's craftsmanship and its endeavors to improve and grow aviation in the future, Monnett took to the podium and made it officia --l by introducing the proof of concept prototype electric motor powerplant, controller, battery pack and charging systems installed in a Waiex airframe.
The proof-of-concept looks exactly like a Sonex from the outside, but uses the alternative energy source.
And for the ethanol crowd, he noted AeroConversion's investigation of converting its versions Aero Vee 2.0 powerplant for use of both ethanol-based fuels. More on that Wednesday, though.
The goal of the electric proof-of-concept, according to Sonex, is to determine the feasibility of a marketable line of Sonex and prototype products.
With the current Sonex staff focused on customer service and sales, it was only a small group of folks from AeroConversion who focused their energies on the new concept, which only took six months from idea to concept plane.
The current non-electric Sonex is a kit-based, basic all-metal two place monoplace suited for the US Sport Pilot.
And for those looking under the cowling to see which company's battery was being used in the proof-of-concept, they were disappointed.

Noted Sonex's Director of Public Relations Mark Schaible, the motor and battery system named no names: "They are proprietary parts we are in the process of developing."
The motor, said Schaible, is more than 90 percent efficient... and the most powerful of its kind. In regard to battery power, most contemporary electric powerplants for gas-electric and pure electric cars and previous generations of RC electric vehicles utilize Lithium Ion battery technology.
While much improved in power density and discharge rate over lead-acid and NiCad batteries, Li-Ion batteries still do not offer sufficient power discharge-to-weight ratio to support an electric powerplant for an aircraft based on battery power alone with market-viable endurance.
Newer RC electric vehicles, cell phones, laptop computers and other mobile devices have been moving toward Lithium Polymer cells, which can safely discharge at a rate of 25 times their capacity, or "25c."
The so-called "E-Flight Team" engineered and constructed 10 battery "safe boxes" to contain eight Li-Poly battery packs per box and consolidate their charge/discharge and balancing wiring into two sets of multi-pin connectors.
The boxes will accommodate natural cell expansion and contraction while safely securing each cell pack and facilitating cell cooling with "cooling foam" padding. The boxes are designed to contain and safely direct fire or explosion within the box through a "blow hole" in the box connected to a small exhaust manifold.
For the proof-of-concept plane, the battery boxes are removed and charged individually.
Further generations of safer, more powerful Li-Poly batteries show the near-term possibility of further extended flight durations, from the current 45 minutes to one hour, while personal electronics and transportation will undoubtedly continue to push improvement of the technology in years to come.

And now to the big questions. When will an actual kit plane be available to the public and how much will it cost? As with any proof-of-concept, company representatives were unable to share specific timelines
However, said Schaible, "We don't want to take too long and we don't want to put out artificial deadlines."
And in regard to price? "Any (final) product will be vastly less expensive than other things out there." In fact, said Schaible, the entire research and development for the project is less than the cost of a ready-to-fly LSA.
A follow-up informational forum is open to the public Wednesday, July 25 at 11:30 am at AirVenture forum building 11.
Founded in 1998, Sonex Aircraft has been providing a series of Sport Pilot-eligible kit aircraft and producing the AeroConversions' line of products that include Aero Vee engine, AeroCarb, and ancillary aviation products.
FMI: www.sonexaircraft.com/aircraft/sonex.html

[quade]

While I would never say never, the current power to weight ratios alone mean that this will, for the foreseeable future be in devolpment and not in practicle use.

It will be interesting to see where this technology goes, but with current flight durations of only 45 minutes to one hour very few pilots are going to want to deal with that. In the US, for instance, a requirement by the FAA is that you have enough fuel to land at your destination AND have a 30 minute reserve (45 minutes if IFR). Even taking this into account would give this aircraft a -very- short range.

[polo_pro]

Nice find Hobbes! An electric power source for a plane offers many options.

1) Redundancy can be more easily built in much like it has on the segway.
2) Fuel costs MAY be less. Currently a typical small plane costs $50/hour in fuel. It's more like $90 to $100 when you factor in maintenance.
3) Weight and balance doesn't change (unlike with a plane where the gas gets consumed and you constantly have to monitor where you're drawing your gas from and how it'll change your performance characteristics when you land).

But on the other side of the coin, I'll bet you have to monitor temperature constantly. You do this to some extent on a regular small plane too. But the consequences of going overtemperature aren't as serious. Having a LiPo fire would be the kiss of death when flying!

In fact, I'd guess any manufacturer would have to include an ejection system for the batteries...not that having flaming falling batteries is going to appeal to the FAA!! Another design consideration would be glide characteristics after ejection. You'd certainly have a new weight and balance, eh?

By the way, Quade, 45 minutes is enough time to practice touch and go's. You're never too far from the airport even if you suddenly lose power. And you'd be surprised how much of flight training is doing this...I'd guess over 50%. I think the real question is how much charge time is required. If you could get an 80% charge in 15 minutes and then run the plane for a half hour or more, then flight schools might be interested in this (assuming time in a sport's plane would count towards the 40 hour requirement for flight training). Especially if the cost of charging was significantly less than AVGAS...heck, maybe we're seeing the "hybrid" effect in planes (but without the gas engine).

ps - Remember planes are made of aluminum that's being seriously stressed as the plane is pushed through the air. When there's a fire, you MUST get it out quickly.

[quade]

By the way, Quade, 45 minutes is enough time to practice touch and go's. You're never too far from the airport even if you suddenly lose power. And you'd be surprised how much of flight training is doing this...I'd guess over 50%.

I used to be a CFI. Upwards of up to 50% of all flying in the US is flight training. That said, in it's current state, this aircraft would NOT be suitable for a training aircraft in any way, shape or form and especially not for pattern work since this aircraft probably isn't the aircraft you'd be trying to keep current in. Nobody in his right mind is going to do pattern work in this if he still has to take a check ride in a C-172. BTW, we'd usually try to schedule training blocks in increments of 1.0 hours on the Hobbs. Time on the ground is another issue. I seriously doubt the plane could be recharged in anything even coming close to 15 minutes. I find it very difficult to believe that with any technology in the nearly foreseeable future you're going to see charge times much less than discharge times. Meanwhile, I call up the fuel truck, it's over and done in 5.

As for fuel costs . . . the reason even a beat up rental C-172 goes for $100 wet isn't primarily because of the "wet". It has far more to do with engine maintenance, tie-down fees and insurance. I know you know this, because you accounted for a bit of that in your post, just re-iterating.

Technology demonstrators are always interesting. That said, it can be a LONG way from technical demonstration to commercial viable. For instance, when was the last time man set foot on the Moon? Heck, at this point I'd still say that even the Segway isn't commercially viable. It's an amazing technology demonstrator that -some- people have found useful in a real world environment, but it's not like the world is actually even ready for them to be used on a mass basis yet.

[Hobbes]

There is more info here: http://www.airventure.org/2007/4wed25/sonex.html

A good use may be for a motorglider, or most likely a self-launching sailplane, since usage is not necessarily for long periods, power requirements are in this range, and the power required to stay aloft is a fraction of the peak take-off hp (maybe in the range of 10 - 20%).

Timeline for commercialization may be 5 years, and that is a long time in batteryland.

[polo_pro]

Originally Posted by quade

Nobody in his right mind is going to do pattern work in this if he still has to take a check ride in a C-172.

I do agree with this point. You're going to want to train in something that is very very close to whatever you do your checkride in. But still I think you can use other tools to aid in the learning process.

In my case I used Google Earth and MS Flight Simulator. Did they help me learn how to land a plan quicker or better? Hell no, but when it came to doing cross country flights, both of these tools were invaluable. The former let me see what I would from the plane at altitude (so I could pick out landmarks more easily), and the latter helped give me a sense of time to gauge when I'd be arriving in the vicinity of the far away airport (or when I needed to verify a checkpoint). By the time I actually did the cross country flights it was a piece of cake!

ps - When I showed my old school flight instructor these tools, he said "You cheated!" 8^) 8^) 8^)

[hellphish]

Originally Posted by quade

I find it very difficult to believe that with any technology in the nearly foreseeable future you're going to see charge times much less than discharge times. Meanwhile, I call up the fuel truck, it's over and done in 5.

This thing charges in 5 minutes and has a 10-15 minute flight time.

[polo_pro]

Originally Posted by hellphish

This thing charges in 5 minutes and has a 10-15 minute flight time.

I've seen those first hand...very cool. Surprisingly stable. Not very durable so be careful not to crash it hard.

[hellphish]

They are actually pretty tough. The main rotor is the strongest part of the heli and it is usually what ends up hitting a wall. The tail rotor is really weak (I already cracked mine) but they supply you with a few of them and offer replacements online.

EDIT: replacement tail rotors

[polo_pro]

Originally Posted by hellphish

They are actually pretty tough. The main rotor is the strongest part of the heli and it is usually what ends up hitting a wall. The tail rotor is really weak (I already cracked mine) but they supply you with a few of them and offer replacements online.

Excellent...I'll tell my buddy who has one.