[Supervolant (OP)]

Hello!

Internal combustion engines of aircraft need oxygen in order to burn their fuel and produce thrust. This isn't the case for all electric aircraft which rely on electro-magnetism in order to run their motors generating thrust.

How much higher can an electric aircraft fly in comparison to an current jet powered design?

I am aware the higher one goes the thinner the air becomes. One has to fly faster in order to fly higher because of lift generation. So at which speeds and how high could and all electric (winged) aircraft fly?

Please ignore current energy density ratios of batteries or anything else and let's just concentrate on the hypothetical speeds and heights such an all electric aircraft could fly at.

I believe this topic to be high interest as all electric aircraft are not a matter of if but of when!

If you are interested in this as well and have something to say please go ahead and shoot me an answer! And to all of you guest's having something to say, go ahead and logg into an account! :-D

Looking forward to all of your answers.

- Robert

Modfiy: I am aware that this topic is highly math depended. If you are an mathematician go ahead and freak it all out!

[Kryptid]

Electric aircraft can indeed fly very high. The Helios HP01 flew above 96,000 feet: https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-068-DFRC.html

The fastest electric aircraft is currently the Long ESA, which can reach 220 miles per hour: https://www.wired.com/2014/07/chip-yates-electric-plane-records/

[Supervolant (OP)]

Electric aircraft can indeed fly very high. The Helios HP01 flew above 96,000 feet: https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-068-DFRC.html

The fastest electric aircraft is currently the Long ESA, which can reach 220 miles per hour: https://www.wired.com/2014/07/chip-yates-electric-plane-records/

@Kryptid Thanks for booth the links! I though the fastest was the last year build and flown EXTRA 330 LE. Which actually flew 210 mph. But it set a new towing record for sailplanes so them...

The thing with the Helios is... it relied on a superwide wingspan in order to generate enough lift even at these extreme high altitudes. What I would like to see is something very fast and high flying but all electric at the same time.

[evan_au]

In the extreme...  If you go high enough, you don't need to fight wind drag and gravity, and you can use an ion drive; this is often used for station-keeping in geosynchronous orbit!
See: https://en.wikipedia.org/wiki/Ion_thruster

[alancalverd]

Problem with extreme high flight is the narrowing corner of the flight envelope between stall speed and supersonic. The U2 spyplane flew in the corner, with glider-like wings, and later high altitude reconnaisance aircraft have been designed for supersonic flight, which burns a lot of fuel.

If you really could ignore fuel energy density, then there is no theoretical objection to an electric Concorde, using an electrically driven jet engine. But if you want to "ignore the weight of the elephant", why not go for an electric rocket, with unlimited altitude and a cruising speed as close to the speed of light as you want?

[Kryptid]

The thing with the Helios is... it relied on a superwide wingspan in order to generate enough lift even at these extreme high altitudes. What I would like to see is something very fast and high flying but all electric at the same time.

You end up with a bit of a problem when you want a propeller-driven aircraft (electric or not) that can simultaneously fly both high and fast. Going fast calls for maximizing the thrust-to-drag ratio, which would normally call making the aircraft as light as possible (to minimize lift-induced drag) and giving it small wings (to minimize form drag and friction drag). A high-flying aircraft would either need to fly fast (to generate large amounts of dynamic lift, as in the SR-71) or have a large wing area (like the U-2). Since even the fastest propeller-driven aircraft can't reach the sound barrier, the dynamic lift method isn't an option. So your electric aircraft is going to require large wings (and therefore have relatively high drag).

The Boeing Condor offers a fairly good model as a potential compromise. It is piston-powered, can fly above 67,000 feet and fly up to 161 miles per hour. It has two engines that produce 175 horsepower (with a power-to-weight ratio of 0.89 kilowatts per kilogram). It may be possible to replace those piston engines with electric engines and get similar performance. There are apparently electric aircraft engines that exceed that power-to-weight ratio: https://newatlas.com/siemens-world-record-electric-motor-aircraft/37048/

[IzzieC]

Hi Robert,

We'd like to try to discuss this on an upcoming show... Can you drop me a message and we can discuss this further?

Thanks a lot,
Izzie