BeechTalk - BT

Username Protected · **Posted:** 03 Feb 2016, 22:10

Stuttgart University just did a return flight over the Alps from Germany to Switzerland and back with their E-Genius. First time it's been done. They covered 370nm and used 84kW of power. With California electricity prices of a rather high 12 cents per kWh, that's a fuel expense of $10 in total. Pretty impressive and shows that electric aviation is possible and viable, although in early stages still.

:thumbup:

[youtube]http://youtu.be/Vr3dX2EClDg[/youtube]

Username Protected · **Posted:** 04 Feb 2016, 12:56

Username Protected wrote:

used 84kW of power.

Did you mean 84 kWH of energy?

It also appears they recharged between out and back flights.

Here is something similar, using approximately 0 kWH:

https://www.youtube.com/watch?v=UcogQyzPOu4

In other words, not clear how much of this was enabled by being a glider, how much of this was electric power.

Mike C.

Username Protected · **Posted:** 04 Feb 2016, 13:00

Username Protected wrote:

used 84kW of power.

Did you mean 84 kWH of energy?

Mike C.

Username Protected · **Posted:** 04 Feb 2016, 13:19

Username Protected wrote:

No, they used 84kW in total. There seems to be huge confusion between kW and kWh in general, perhaps more so amongst electrical engineers ;) . kWh is a time based measurement. If you want to know how much kWh they used, divide the 84kW with how long the flight took.

Those electrical engineers, man, they are so screwed up when it comes to kW and kWH confusion. Good thing you know the difference.

Mike C.

Username Protected · **Posted:** 04 Feb 2016, 13:35

For both flights combined, only 83 kWh were needed, the energy contained in 9.2 l of fuel. This leads to a total energy expense of only 21€ for the whole trip, assuming current electricity prices in Germany.

If the flight took one hour 83kWh would be correct. It probably didn't.

Username Protected · **Posted:** 04 Feb 2016, 22:04

9.2 L is only 2.43 gallon at $3, thats $7.30 total, or under $10 at $4 per gallon.
just saying...

Username Protected wrote:

For both flights combined, only 83 kWh were needed, the energy contained in 9.2 l of fuel. This leads to a total energy expense of only 21€ for the whole trip, assuming current electricity prices in Germany.

If the flight took one hour 83kWh would be correct. It probably didn't.

Username Protected · **Posted:** 04 Feb 2016, 22:31

The press release is underselling the efficiency of the airplane and its powerplant.

84kWh (which is about 113 horsepower-hours) would take about 8-9~ish U.S. gallons of avgas burning in one of our lycon engines to create (or a bit more than that amount of Jet A in a light turboprop).

Username Protected · **Posted:** 05 Feb 2016, 17:13

Username Protected wrote:

In other words, not clear how much of this was enabled by being a glider, how much of this was electric power.

Mike C.

If it were a glider it would have had to get up there somehow, either with a tow or onboard gasoline engine. Seems like electric power played a significant role, right?

Username Protected · **Posted:** 05 Feb 2016, 18:22

Username Protected wrote:

If it were a glider it would have had to get up there somehow, either with a tow or onboard gasoline engine. Seems like electric power played a significant role, right?

Depends on what you mean by significant.

You can do a winch tow to 800 ft, using less than 1 KWH of electricity, and then fly a 1000 miles in a glider.

So does that mean the glider can fly a 1000 miles on 1 KWH? Well, not really.

The point is the plane is a glider with a small electric motor and a big battery pack (~500 lbs). It gets its performance predominately from being a glider.

Mike C.

Electric flight over the alps.