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Patrick14 02-28-2018 04:40 AM

Electric Hybrid
Good Morning!
Is anyone working on a hybrid propulsion System? For example Siemens Electric Motor downrated to 130kw, "small" 40 kWh battery and a Rotax, Limbach, Jaribu or similar to feed the battery

control 02-28-2018 05:19 AM

I did dream about that but soon realized that, that is something for someone who is building the 3rd or 4th aircraft.

As a first time builder I will stay very close to the plans and mainstream... :)

Gillegan 02-28-2018 08:01 AM

As I understand it (and someone correct me if I'm wrong) in hybrid autos, energy that is normally dissipated through braking, coasting down hills, etc. is converted to electrical energy for the batteries. Those opportunities generally wouldn't be available in an aircraft.

Now if someone could figure out how to convert the energy lost due to skin friction to electrical energy, we might be on to something.

control 02-28-2018 08:51 AM

I have a VW Passat GTE, the energy saved from braking is not noticable. And in an aircraft you would get the same effect if you use the prop as a brake when going down....

I toyed with the idea of having a Siemens engine with a max effect when using both the battery and petrol engine of 250hk+ at altitude I would use a Rotax/generator delivering 80-100hk(max 125).

The battery/electric engine should give 150hk+ for at least 15min from fully charged.

Many daydreams about this... maybe when my very soon to be delivered new Lycoming has had 2000+ hours :)

Patrick14 02-28-2018 08:58 AM

a serial hybrid just means that the electrical power for the propulsion is made available by a second, in this case fuel burning piston, engine. The fuel engine could be much smaller and could run on cheap fuel in its most economic range .The Electric motor with its high torque could drive a large diameter slow turning propeller. 130 kW Motor, 40kwh buffer battery and a 120hp gasoline engine should do. As AVGAS prices are astronomically high over here and availability is uncertain for the future, i would highly appreciate this more efficient system, even if it would be more complex, expensive and heavier than the lycoming. Unfortunately its out of my first time builder capabilities. Did anyone try already?

Ps please excuse the typos...

smokyray 02-28-2018 10:26 AM

Vie Gehts Patrick,
Two years ago I replaced the aging 2180CC VW engine in my Sonerai IIL with a new 1835CC VW (blueprinted specifically for aircraft). The engine builder had removed it from his Q2 in lieu of electric power.
His choice of power? The Electraflyer installation:

I think EP is a viable alternative in the RV12 or maybe a new RV design yet to be engineered... Pipistrel is already flying an approved LSA down under....

Check this out:


Mel 02-28-2018 10:48 AM

Unfortunately electric power does not meet LSA parameters in the U.S.....


Mike S 02-28-2018 11:10 AM

Welcome to VAF
Patrick, welcome aboard the good ship VAF:D


Originally Posted by Patrick14 (Post 1242743)
Good Morning!
Is anyone working on a hybrid propulsion System? For example Siemens Electric Motor downrated to 130kw, "small" 40 kWh battery and a Rotax, Limbach, Jaribu or similar to feed the battery

Why use an engine that is designed to directly power a propeller in this situation?

What you are proposing looks like this;

Aircraft engine->generator/alternator->battery->speed control->electric motor->propeller

You are adding weight, cost, complexity, and probably loss of efficiency throughout the system.

I would think it would make more sense to use a engine/generator package that is designed from the ground up to be such. Think Honda eu200i for example------light, cheap, light, hugely successful track record, runs for hours on very little gas. Obviously this particular generator is not enough to run the plane on its own, but I only cite it as an example of what seems to me to be a much better choice instead of the OP suggested setup.

kgood 02-28-2018 12:07 PM

check out

If this works out, it sure isn't a bad idea to have 10-15 min of flying time available in case of an engine stoppage, and have extra power on takeoff when needed....


Patrick14 03-01-2018 03:06 AM

Hallo SmokeyRay,

thanks for the link. Sounds promissing. I think pure electric would unfortunetly not fit to the current design of the RV7 i am going to build. Batteries would be too heavy for 2hrs of flight at 100hp.:(

Hi Kurt,
thanks for the link! I never heard of them before. Sounds similar to what Thielert did a couple of years ago. Most probably a Mercedez Benz 4 cylinder diesel engine adjusted for aircraft use. I have contacted them to find out if:
a) it is aerobatic/inverted capable
b) recommended inflight adjustable propeller
c) pricing

Does anyone know somebody with experience on this system?

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