# Electric trainer aircraft has engine weighing 11Kg , how much would a comparable conventional engine weigh?

The Pipstrel Alpha Electro Trainer has an electric engine which weighs 11Kg.

How much would the engine of a comparable gasoline powered aircraft weigh ?

• You need to compare apples and apples... What does the engine and the batteries weigh, and compare that with a gas engine and fuel. Nov 5, 2019 at 22:07
• I'm not sure why this is a question, the Wikipedia article the OP linked to has the specifications for the gas powered Pipstrel Alpha, and fuel capacity. Nov 5, 2019 at 22:23
• What I've been able to discern from the electric paramotor business is that the power density of electric power per pound overall is roughly 1/3rd that of a gasoline engine. Good enough for lots of uses, but not quite there as a universal application. Nov 5, 2019 at 22:24
• The electric motor may weigh only 11Kg but there are other weights that should be included in comparison to a piston engine. In addition to the batteries there is a liquid cooling system for the electric motor. This cooling system includes coolant, radiator, pump, controls, etc. that are not found on a conventional air cooled piston engine. Nov 5, 2019 at 23:55

The Pipstrel Alpha Electro is an electric version of the Pipistrel Alpha Trainer which has a Rotax 912ul engine. The Rotax 912ul weighs 60kg.

For comparisons sake;

The Pipstrel Alpha Electro has a 11kg motor and 126kg of Lipo battery cells for a total of 137kg and about 1hr of flight time per charge.

The Pipistrel Alpha trainer has a 60kg engine and carries 35.5kg of fuel for a total of 95.5kg and 5-6hrs of flight time per tank.

flight time estimates are made assuming the planes are being used in a touch and go trainer role. At cruise speed flight times would be less.

EDIT for question in comments: The electric motor and Rotax engine both make 80hp. specs on the electric plane can be found here: https://www.aopa.org/news-and-media/all-news/2015/october/pilot/f_pipistrel and https://www.pipistrel-usa.com/alpha-electro/

• Much more comprehensive answer than mine, but you might need some references.
– Noah
Nov 5, 2019 at 22:22
• Not sure if this actually answer the "comparable" part of the question, i.e. is the electric motor 80HP? If not then the 60kg gas engine shouldn't be considered "comparable", even though it's used on a similar airplane. Nov 5, 2019 at 22:54
• @user3528438 The Siemens 60-kW/80-hp electric motor and the Rotax 912ul both make 80hp so it is very much "comparable". Specs can be found here: aopa.org/news-and-media/all-news/2015/october/pilot/f_pipistrel I'll edit my answer though. Nov 5, 2019 at 22:58

Let me begin by saying I agree with the comment left by Ron, batteries are very heavy!

But to answer your question, Most medium sized trainers use a "360" engine built by either Lycoming or Continental.

A Lycoming O-360, an older, N/A engine fitted with a carburetor, weigh between 124.7kg and 137.4kg. Source.

Whereas when you "Kit Out" your Lycoming engine with a turbo and fuel injectors (TS-IO-360), they can weigh between 171.9kg and 184.6kg. Source.

If you're interested about what all the numbers and letters in an aircraft engine code mean, have a look at this Continental PDF documenting it all.

• The non-electric Pipstrel uses a Rotax 912UL, it would be better to compare it to that instead of a Lycoming or Continental. Nov 5, 2019 at 22:22
• Yeah, in retrospect I agree. I just know very little about the Rotax engines and thought it was best to share the knowledge I have rather than tell OP about something I'm not sure about.
– Noah
Nov 5, 2019 at 22:29