Electric powerplant on RV?

[mchargmg]

Hey all,
This is a really interesting post. Two companies come to mind on the electric powerplant front.

The first is Pipistrel, it now has a certified version of the E-811. It is the basis for their Alpha Electro, which is now flying. This is a small engine, 50 lbs, 77 hp for a minute, and 67 hp continuous. Too small for an RV it seems like. They sell an entire powertrain, including battery packs, for this system. I have no idea how much it costs.

At the other end of the spectrum is Magnix. Their "little" engine is the Magni250, which provides 375 shp continuous. They do have the inverter system developed as well. Last year when I talked with them, they were not interested in selling to the experimental market. They are pushing the "bigger" engine, the Magni 500 which is 750 shp continuous.

The Magni 250 engine is flying, Magni is working with a flightseeing company in Seattle that wants to electrify their Beaver aircraft. They and Magni have one of the Beavers flying and are working on getting it certified. This use case actually may make sense. None of the flightseeing flights are long, but the run multiple flights a day. Additionally, it turns out they put the Magni 500 into a Cessna Electric Caravan. Again, apparently Magni thinks there is a busness case for "ultra short flying."

All of the hard parts of this are the batteries and cooling. I imagine it will be a couple of years before this gets sorted out. If you could manage to buy one of the powertrains, it might be a fun project to take an older RV, rip out the engine, and replace it.

Anyway, I think this is a technology worth keeping track of!

Blue skies

Geoff

[Mike S]

Originally Posted by Aluminum

This one makes a whole lot of sense.

It does???

Range 25 miles.

Recharge time 5.5 to 7.4 hours for the most commonly found electrical source.

A hundred mile flight thus equates to 4 flight legs, with a minimum of 22 hours charging time to make the flight.

At the 62 mph listed, that is slightly over 1.5 hours flight time, 22 hours charging time. Toss in 10 minutes each charging session just to get hooked up , unhooked and misc.

So, your 100 mile flight has taken 24 hours to accomplish.

Sorry, this doesn't make much sense to me.

Yes, it is interesting tech, and a fun looking craft with an interesting flight capibility.

IMHO for electric flight to get to be more than just a novelty, you need to be close to the performance of gas powered aircraft in; load carrying ability, range, speed, refueling (charging) time and cost.

Dont get me wrong, I am not against electric flight, I am just trying to see the total picture and ignore the koolaid. I look forward to the time I can plug in my plane at night and then go fly out for an hour or two, at 150 mph. Then turn around and fly home and land with the same reserves my gas powered plane has. Plug it in again and be ready for the next flight tomorrow

Maybe someday.........

[terrye]

The electric Beaver is a collaboration between Harbour Air of Vancouver and Magnix who supplied the motor, power controls and did the systems integration. I attended the EAA webinar back in July (during Airventure) presented by Magnix and it was very interesting. Unfortunately I couldn't find it in the webinar archives. The stated goal was to electrify a Beaver for future scheduled local flights and prove (or disprove) the viability of the concept. Harbour Air and Magnix were very secretive about the payload remaining after the batteries were installed, but I heard a rumor that it was just the pilot.

I haven't heard any more from Harbour Air or Magnix after the test flight, but I believe the viability depends on another step change in the battery power/weight ratio.

All battery powered vehicles suffer from poor payload and/or poor range. Although battery technology is progressing with lots of research and development in many countries, I think the power density has to increase by a factor of 3 or 4 to be viable in an airplane.

Having said that, I think an electric motor is the perfect powerplant for an airplane: relatively light weight, low vibration, no altitude de-rating, no poisonous exhaust, etc. But when you add the weight of the batteries, inverters and power controls, well...we're still years away.

[rv6n6r]

The RV-12 seems like an excellent candidate for this sort of experiment. But it would be just that (an experiment) as battery technology is still a ways from getting us the all around utility that most of us are looking for.

It sure would be fun to try however, just imagine replacing that big expensive heavy collection of complicated parts barely containing a carefully timed series of explosions, with something that has the same number of parts as your alternator.

I wish I had the money & extra engineering know-how to play with it. I expect someone will. No, it wouldn't go very far - yet. But with improvements in battery technology, you'd be able to drop in (ish) better batteries as they come along and perhaps even get comparable utility some day with only minor modifications along the way.

[rv8ch]

I think there's no doubt that the battery density improvement trends will continue. It's almost already at the point where it makes sense to have electric training aircraft. Very powerful electric motors are already available.

I've read that the primary driver behind the battery technology improvements are the guys making electric screwdrivers. I'd have thought it was the car guys, but apparently we buy a lot more total electric screwdriver batteries than electric car batteries.

[1001001]

There are some very interesting innovations happening on the electric battery front now, but none of them promise (yet) to achieve energy densities on a par with liquid fuels.

In reality, an electric battery will need to achieve slightly better energy density than liquid fuels, as they do not benefit from the increased performance due to loss of mass in flight that liquid fuels offer.

I'll be happy to convert to electric propulsion when it offers me *an advantage* over liquid fuels. And that includes the environmental effects of manufacturing and disposing of the batteries. Until then, internal combustion with liquid fuels is the technical winner.

I don't discourage people from experimenting and developing better electric energy storage options, but as a consumer, I'll not be an early adopter.

[emsvitil]

I can see a hybrid system working.

2 power plants for takeoff, 1 for cruise.

Depending on mission, I'm not sure which power plant would be better for cruise.

[zolotiyeruki]

Originally Posted by emsvitil

I can see a hybrid system working.

2 power plants for takeoff, 1 for cruise.

Depending on mission, I'm not sure which power plant would be better for cruise.

Similar to hybrid cars, I'd expect that the gas engine would be for cruise (and recharging batteries). That way, you can size and tune the engine for maximum efficiency at cruise, and the required battery pack could be greatly shrunk to only the size needed for takeoff.

My question is: what would the actual gains be? If you fly with a 160HP 320 and cruise at 75%, you could maybe replace it with a Rotax 914 or an 0-235, which would free up maybe 100 lbs. Once you subtract the weight of the electric motor, you don't have a whole lot of weight allowance left for batteries.

[BillL]

Originally Posted by FlyGuy65

Maybe just my flawed memory, but it seems that when electric motors came to model rc planes, there were a lot of attempts to fit them to existing designs. However, the existing designs were built around heavy, vibrating engines and the need to protect against oil exhaust and fuel proofing. A brand new plane designed specifically around electric power might be the key?

Having been in an engineering research org for a few years, this is the 99% case. This is why the Prius design is much more value added than nearly all other hybrids. Cars work because of energy lost to various things, braking being the most significant, then allowing the gasoline power plant to operate much more efficiently w/o operation compromises or not operating at all.

Electric motors require amps, amps yield torque, amps require copper, copper is heavy. PM motors of certain configuration can operate quite efficiently at high rpm, without the friction losses like a recip engine. I dont understand all these direct drives?? It would be a lot more weight efficient to use a low amp, high voltage (400-600), high speed motors with an efficient gear box. Another development of it's own.

A test platform for learning is fine, but the component technical objectives and technology roadmaps seem to be missing in aviation. The US government research program managers do a pretty darn good job of driving these roadmaps.

[BillL]

Question: is a propellor more efficient than a higher rpm ducted fan with blades optimized for a fixed speed? It would seem the friction drag of a lot of surface area would outweigh tip losses? Isn't that why large turbines are more efficient than smaller diameter?