>Looking at historical data

>One interesting aircraft in the historical data:

Lancair Evolution

P/W Power to weight ratio 7.54 kg/kW, 12.28 lbs/hp.
W/S Wing loading 142 kg/m^2, 29.05 lbs/sqft
Stall speed 61 kts
Empty weight to gross weight ratio: 0.55
Fuel to gross weight ratio: 0.2
Aspect ratio: 10.3

Aircraft with 12.28 lbs/hp power loading and 29.05 lbs/sqft wing loading in other words can
be made to climb, and it can also meet FAR 23 in stall speed requirement (61 kts). According to an article, the LC Evolution demonstrated glide ratio of 1:22 which is amazing compared to the competition, especially achieving this with only AR=10.3.

With these parameters, a smaller Rotax powered twin aircraft would be sized as follows:
Engines: 2 x Rotax 912UL, each turbocharged at 100 hp
Gross weight: 1116 kg
Empty weight: 0.55 * 1116 kg = 613 kg
Fuel weight: 0.2 * 1116 kg = 223 kg
Fuel volume: 314 l
Wing area: 1116 kg / 142 kg/m2 = 7.75 m2
Useful load (including fuel): 503 kg
Useful load full fuel: 280 kg
Endurance: 10.4 hours

– achieving the stall speed of 61 kts, requires very high Clmax for the flapped airfoil
– achieving > 20 glide ratio with lower Re, requires higher AR most likely
– achieving positive climb rate with single engine
– achieve the Clmax with wings that carry two engine pods on them (blanketing potentially flap and part of the wing).
– The fuel potentially does not fit inside the wing of this low wing area.

What it shows:
– Still with this high wing loading, it would be possible to fit three adults on the plane with full fuel. The result is not at all bad compared to any production aircraft.
– Empty weight looks realistic taking in account there are two Rotax engines on the craft. It is higher than it would be if it was relatively as lightweight as a Dynaero.

Bottom line: The parameters of the Lancair Evolution are very impressive and inspiring.

Realism hits:

Reduce the wing loading to 120 kg/m2
Wing area becomes: 1116 kg / 120 kg/m2 = 9.3 m2

-> It ends up in the magic 9.3 m2 wing area I have ended up from many directions already several times before.

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