8-10 kg of batteries?
It means capacity of +-2 kWh.
For TakeOff power 14 kW you have discharge rate of 7C.
It is your project just...
I really recommend you to make several ground tests with max. power and power necessary for level flight with detailed measurement of temp. of battery cells and motors. It will give you some impression how long you can use max. and cont. power.
Part 103 plane needs only 8-12 KW for take off. Plane works as a plat form for several FAI records...with more batteries and 14 KW of max power.
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There are several aims with this:
1. Finnish 70 kg motorglider...that is first intented...with 8-10 kg of batteries.
2. Part 103...that can have flaps and more batteries as it is 115 kg limit ( 5 gallons worth ? ).
3. Certified ultra under 300 kg.
Plane has very low stall speed at 70 kg weight...so it fits PART 103 as such.
I hope this clear the subject.