In rec.aviation.piloting Morgans wrote:

wrote

Well, to be fair, there is solar cell research that if it becomes
practical and cheap enough would work on sail planes with lithium
batteries.

Are you sure about that?

I think I recall seeing someone do the calculations of how much solar energy
hits the top surface of a sailplane and wing, and it was still not enough to
motor without thermals, if it was all converted to electrical energy.

Anyone better in math, than me, want to take on that supposition?

In rough numbers, you get about 1 kW/m^2 of energy from the sun on
a clear day.

Current conversion technology is about 22% at best.

Technologies in the works are promising 50-60% (the check is in the
mail and I will respect you in the morning).

One presumes a sailplane is going to spend most of its time sailing
and only using the motor (with batteries) to get off the ground
and occassionaly cruise between thermals.

So most of the time you are just charging the batteries.


--
Jim Pennino

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