Thx Graham,
My sentiments exactly.
And to the question of why the spars are strapped together, and why one pin h
as to be a pip pin, is because we have simple overlapping spars, and not for
k spars, so the asymmetrical load on the pins wants to twist them off, as th
e spar ends gets forced away from the other spar.
Cheers,
Pete
On Jul 2, 2013, at 8:19 AM, GRAHAM SINGLETON <grahamsingleton@btinternet.com
> wrote:
> Svein
> I admire your patience and courtesy, the persistent deniers on this tread
have
> just about exhausted mine! First of all one should start with the facts; w
hen a wing
> fails due to high positive load it claps forwards. Saying "I don't believe
it because it
> doesn't fit my understanding or theory might be described as "an academic r
eaction to an inconvenient truth"
> This "forward lift component" is very counter intuitive, the only way to a
pproach it is to
> refer to a diagram like yours. The criterion a lot of people overlook is t
hat lift is
> perpendicular to line of flight, which is NOT parallel with the centre lin
e of the fuselage.
> Nor is it 180deg from the line of gravity.
> Graham
>
>
> From: Sidsel & Svein Johnsen <sidsel.svein@oslo.online.no>
> To: europa-list@matronics.com
> Sent: Tuesday, 2 July 2013, 7:23
> Subject: SV: Europa-List: Re: wing lift/drag pins
>
> Ron,
>
> =46rom your message:
>
> > Attached is a diagram that is a pretty good visualization.
> > Ron P.
> >
> > Here's his reply:
> > No it=C3=A2=82=AC=84=A2s not=C3=A2=82=AC=C2 (a good visualiz
ation)
> >
> > You have to apply real numbers to those phoney scalers on that figure.
> >
> > At high AOA the drag is significantly higher than shown, but lift not so
much
> > so. This would pull the L/D resultant much father aft.
> >
> > Those two plots are implying that the L/D of a wing is the same at cruis
e and
> > at high AOA which we all KNOW is not true! (the reason you never fly a h
igh
> > performance sailplane near Cl Max!)
> >
>
> I assume it was my illustration that you forwarded to your friend. If so,
I agree with his statement about L/D - the vectors are not to scale at all
, and were not intended to be. I realize, however, that I should have empha
sized this and also increased the length of the wing drag vector at the high
AOA illustration, but this has no bearing on the lift component issue.
>
> My message =93 and illustration - had two purposes, which perhaps yo
ur friend was not aware of:
>
> - To show that lift has no component in the direction of flight, r
egardless of the angle of attack, while lift may have a =9Cforward
=9D component, if "forward" means the direction the nose is pointing.
> - To show that a glider is pulled forward (in the direction of gl
iding flight) by gravity, not by any lift component.
>
> I have not made any calculation of the magnitude of the =9Cforward
=9D lift component vs. drag on Europa or any other airplane, which is why
I just referred to arguments and observations presented by others: "At so
me point it may, as I read the discussion, become larger than the wing DRAG
=99s component parallel to the centerline in the opposite direction, givi
ng a net =9Cforward=9D force on the wing." The magnitude of su
ch a =9Cforward=9D component is only dependent on the magnitude o
f the lift and the angle between the centerline and the direction of flight.
The magnitude of drag does not come in here. The resultant force on the w
ing, however, and whether it acts =9Cforward=9D or =9Cback
ward=9D, depends also on the drag magnitude.
>
> I apologize if I have caused any confusion about wing L/D vs. AOA (I don
=99t really think I have, though!)
>
> Regards,
> Svein
> http://www.matronics.com/Navigator?Europa-Listofollow"; target="_blank" h
ref="http://www.matronics.com/contribution";>h
>
>
>
>
>
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