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Francis' article in the last magazine

Posted: Fri Jan 24, 2014 6:15 pm
by Basil
In the last LAA magazine Francis said that it was unlikely that the SD1 or the luciole would comply due to their high wing loading and stall speed. The SD1 is accepted as a microlight in Germany where the same 65kph max stall speed is required and the designer,Igor Spacek, says all examples have stalled below 35kts.
Looking at the aerofoil used this seems quite feasible.
The Luciole has a wing loading 3kg/m2 higher than the SD1 so it would always be a bit marginal. Does anyone know the aerofoil used on the Luciole so I can try to check out why the stall speed seems so much higher?


Re: Francis' article in the last magazine

Posted: Sat Jan 25, 2014 9:08 am
by Brian Hope
Hi Basil, I'm afraid I don't have the answer to your query re wing section of the Luciole but FYI in the February issue Francis expands the stall speed discussion with a more in depth, though not highly technical article on how you can assess probable stall speed in relation to wing profile/flap/slat etc.
On a pragmatic note, I think with the differing experimental/homebuilt regulations that are in place around the world, the assessment of stall speed differs enormously - from somebody looking at what it reads on an uncalibrated Mickey Mouse ASI, to conducting a series of flight tests with certified accurate instrumentation and pitot set ups. I think we have to take ‘published’ stall speed with a sizeable pinch of salt (that said I have no knowledge of how stated the SD1 stall speed figure was arrived at).
Reality is that the CAA is not going to test every (if any) SSDRs for stall speed, particularly if they exhibit the appearance of being representative of the intention of the regulations. Flaunt the rules with a minimum weight F1 replica machine that clearly stalls at around 60kts and it might be a different manner.
There are several Luciole’s well on the way to completion in the UK now, hopefully we might see another one flying this year to join from Richard Teverson’s very nice example. Richard by the way, is absolutely delighted with the aircraft and is wracking up plenty of hours in it, he probably has over 250 by now. The engine has behaved itself perfectly and performance meets expectations, which is a real stimulus to those who would like to build something similar within SSDR – it is possible to come up with a really practical ultralight aeroplane.

Re: Francis' article in the last magazine

Posted: Sat Jan 25, 2014 10:56 am
by Basil
I look forward to reading it.

I was trying to establish if the reported high stall speed of the Luciole was due to being optimised for fast cruise. I intend to built an SD1 under the new SSDR regs.