Ron, Somewhere I have seen a picture of the wings loaded up with sandbags to
a total of 10g - presumably the biological bits fail well before the wings.
I did understand that you were talking about the outer sections effectively
developing negative incidence when the flaps are down at high speed. However
since the inner section of the wing (& principally the flaps) have to
provide lift equal to the weight of the plane plus any negative lift being
developed by the outer wing (& possibly the fuselage) my bet is on the flap
brackets failing well before the wing, & and while I would be relaxed about
going a bit above Vne I would not want to exceed flap speed significantly.
Regards, David Joyce, G-XSDJ
----- Original Message -----
From: <rparigor@suffolk.lib.ny.us>
Sent: Friday, December 15, 2006 6:32 PM
Subject: Re: Europa-List: Vne Speed
>
> Hello David
>
> "In Don Dykin's booklet about Europa aerodynamics he says that the flaps
> take just about half of the plane's weight at top flap speed. With
> aerodynamic forces increasing with speed squared I wouldn't want to rely
> on
> the flaps not failing before the wings, which have been tested to 10g
> after
> all!"
>
> Were the XS short wings really tested and held up to 10 Gs, or was it
> closer to 6 before failure?
>
> I think the glider wings are stronger, and perhaps 10 on them?
>
> What I was getting at, is with flaps down you have a wing that kinda sorta
> has 30 degrees washout. Go much faster than max flap extension speed and
> the tips are pushing through at a negative angle of attack, and the area
> near flaps at a positive angle of attack. The net needs to be enough to
> keep the plane in the air. There is this twisting and each half of the
> wing fighting each other that is a very awkward.
>
> Can this fight I speak of overload the wing in the middle and break it?
> Can this fight I speak set up for flutter and break it?
> Can this fight I speak of set up flutter in the ailerons?
> Will the flaps flutter and depart?
> will the flaps overload the attachments and depart?
>
> Don't know exact, but the drag and lift bars double convinced that
> exceeding max. flap down speed is not a good idea, evil begins full
> hearted when you do.
>
> Ron Parigoris
>
>
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