Svein=0AI admire your patience and courtesy,=C2- the persistent deniers o
n this tread have =0Ajust about exhausted mine! First of all one should sta
rt with the facts; when a wing =0Afails due to high positive load it claps
forwards. Saying "I don't believe it because it =0Adoesn't fit my understan
ding or theory might be described as "an academic reaction to an inconvenie
nt truth"=0AThis "forward lift component" is very counter intuitive, the on
ly way to approach it is to =0Arefer to a diagram like yours. The criterion
a lot of people overlook is that lift is=0Aperpendicular to line of flight
, which is NOT parallel with the centre line of the fuselage.=0ANor is it 1
80deg from the line of gravity.=0AGraham=0A=0A=0A=0A=0A____________________
____________=0A From: Sidsel & Svein Johnsen <sidsel.svein@oslo.online.no>
=0ATo: europa-list@matronics.com =0ASent: Tuesday, 2 July 2013, 7:23=0ASubj
ect: SV: Europa-List: Re: wing lift/drag pins=0A =0A=0A=0ARon,=0A=C2-=0AF
rom your message:=0A=C2-=0A> Attached is a diagram that is a pretty good
visualization.=0A> Ron P.=0A> =0A> Here's his reply:=0A> No it=C3=A2=82
=AC=84=A2s not=C3=A2=82=AC=C2 (a good visualization)=0A> =0A> You
have to apply real numbers to those phoney scalers on that figure.=0A> =0A>
At high AOA the drag is significantly higher than shown, but lift not so m
uch=0A> so.=C2- This would pull the L/D resultant much father aft.=0A>
=0A> Those two plots are implying that the L/D of a wing is the same at cru
ise and=0A> at high AOA which we all KNOW is not true! (the reason you neve
r fly a high=0A> performance sailplane near Cl Max!)=0A> =0A=C2-=0AI assu
me it was my illustration that you forwarded to your friend.=C2- If so, I
agree with his statement about L/D =C2-- the vectors are not to scale at
all, and were not intended to be.=C2- 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.=0A=C2-=0AMy message =93 and illustration - had two purposes
, which perhaps your friend was not aware of:=C2- =0A=C2-=0A-=C2-=C2
-=C2-=C2-=C2-=C2-=C2-=C2-=C2- To show that lift has no comp
onent 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. =C2-=0A-=C2-=C2-=C2-=C2-=C2-
=C2-=C2-=C2-=C2- To show that a glider is pulled forward (in the di
rection of gliding flight) by gravity, not by any lift component.=0A=C2-
=0AI 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:=C2
- =C2-"At some point it may, as I read the discussion, become larger th
an the wing DRAG=99s component parallel to the centerline in the oppo
site direction, giving a net =9Cforward=9D force on the wing."
=C2- =C2-The magnitude of such a =9Cforward=9D component is
only dependent on the magnitude of the lift and the angle between the cent
erline and the direction of flight.=C2- The magnitude of drag does not co
me in here.=C2- The resultant force on the wing, however, and whether it
acts =9Cforward=9D or =9Cbackward=9D, depends also
on the drag magnitude.=0A=C2-=0AI apologize if I have caused any confusio
n about wing L/D vs. AOA (I don=99t really think I have, though!)=0A
=====================
|