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Stall Speed / CLmax /magic

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Foundationer

Well-Known Member
Joined
Nov 29, 2016
Messages
246
Location
London
Here in the UK we have SSDR ultralights, the rules are: MTOW under 300kg (660lbs), Stall speed 35 knots CAS (18m/s).

Having a look at the numbers for a few of these the stall speed numbers seem... unlikely. Taking published numbers for area they seem to have CLmax in the 2.1 to 2.4 range with plain flaps. Ones I was looking at were B612 (CLmax 2.43), SD1 (2.1) and MC30 Luciole (2.2).

With a decent airfoil and plain flaps I can come up with something in the region of wing CLmax 1.65.

So what's going on here?

Links to the various aircraft:
http://www.a4aviation.co.uk/b612-aircraft-2/
http://sdplanes.co.uk/sd-1/design/
https://en.wikipedia.org/wiki/Colomban_MC-30_Luciole
 
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