That's interesting. As a glider tow pilot I have long been wondering about making the ultimate tow plane. With a range of 10-15 minutes, it should e possible to do 10+ tows in one charge. With an easy battery cartridge system, replacing the used battery with a fully charged one is done in seconds. The plane has to be purpose built for glider towing, max L/D at the right speed etc, and 2-300 hp or more. Up to 5-600 hp should be no problem, but probably overkill. The aircraft will of course charge on the way down, as a small-ish bi-effekt of steep descent, and will off-set some of the battery weight. It would be fun to optimize this concept.I compared 2 power-plants, similar power, electric vs internal combustion engine (ICE). The result I condensed in the following graph:
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The electric motor weight is only a fraction of the weight of the ICE. The graph sows that for short trips the weight of electric motor + batteries is smaller than for the ICE + gas. It seems that for aircraft specifically designed for short trips, under an hour, it makes sense to go fully electric.
I used values for real batteries you can buy and weight data from engine and motor datasheets. The future batteries I expect to be better in the specific energy department so it makes sense to start investing in an electric power plant. The fact that an electric motor does need only a fraction of the cooling compared to an ICE, so reduced cooling loses and the fact that cowling can be more aerodynamic, reducing drag is not taken into consideration, and only can help.
I did this for a study on personal VTOL aircraft that could be used for commuting. For a VTOL aircraft there is a big difference in how much power is needed in hover/transition versus cruising. In this case an electric motor have also the advantage to be highly efficient even when needs to output only a fraction of it's maximum power.
More details about my project here: aliptera.com
The "proof of concept" have already been done by Siemens and Extra, although the Extra 330 must be a very un-optimal airframe.