Ron,
>From 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
visualization)
>
> 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
cruise and
> at high AOA which we all KNOW is not true! (the reason you never fly a
high
> 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 emphasized 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
your friend was not aware of:
- To show that lift has no component in the direction of
flight, regardless 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
gliding 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 some point it may, as I read the discussion,
become larger than the wing DRAG=99s component parallel to the
centerline in the opposite direction, giving a net
=9Cforward=9D force on the wing." The magnitude of such a
=9Cforward=9D component is only dependent on the magnitude
of 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 wing, however, and whether it acts
=9Cforward=9D or =9Cbackward=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
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