Kenn Sebesta wrote on 2/5/2021 7:02 AM:
On Tuesday, February 2, 2021 at 4:26:10 PM UTC-5, David Scott wrote:
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Practically, it's not easy to find the right combination of propeller and motor and battery and layout which works. Every glider has its own peculiarities, and those need to be negotiated at some cost of time and money.

I would caution you against considering anything but the lightest of gliders. There's nothing wrong or unsafe about larger self-launching gliders, but when you're pulling this together in your shop it's a world of different if you're working with a 15kW motor, a 3kW-hr battery, and a 1.3m prop vs. a 40kW motor a 6kW-hr pack, and a 2m prop. Good candidates are the AC-5M and the Carbon Dragon. The former because all you have to do is swap out the existing engine, and the latter because it's so very, very light.

I've been comparing electric self-launching gliders, including the JS3 RES (15M), GP15,
miniLak, and Silent Electro. It became obvious the dramatic difference low weight can make in
powered performance. For example, when both have the "big batteries": the JS3 RES 15M is 250
pounds heavier than the GP15, and for that reason it's max altitude gain is about 9000',
compared to 13,000' for the GP15.

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Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1