What are the L/D ratios of the two Solar Impulse airplanes? I haven't been able to find them.
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asked Mar 2 at 3:29
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1 Answer
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Solar Impulse1 had 4 × 7.5 kW (10 hp) electric motors and a MTOW of around 4400 pounds, and was able to cruise at 43 mph, with 11 foot propellers.
Solar Impulse 2 had 4 × 13 kW (17.4 hp) each at 5100 lbs, and was able to cruise at 56 mph, with 13 foot propellers.
According to this article, the lift to drag ratio was around 37:1.
Rough calculation of 4 × 17.5 hp cruising at half throttle generating 4 pounds of thrust per hp
5100 lbs/(4×17.5 hp×4 lbs/hp×0.5) = 36.4
This is quite good for powered aircraft$^1$. Airliners range in the high teens, with the U-2 at 25.6.
$^1$ unless they can retract their power unit into the fuselage
answered Mar 2 at 14:12