On Jan 2, 10:38*am, Andy wrote:
On Jan 1, 8:29*pm, "
wrote:

Then.....if the tow rope provides a forward and Downward pull........
(which was pretty much proven in an earlier discussion, by virtue of
the 'sag" in the rope, the angle at which the rope meets the
glider) * *then lift has to be GREATER than what you might at first
think. *

I was not part of that earlier discussion and I certainly don't accept
that conclusion.

All I have read here is that the D2, because of its very low angle of
incidence, may have a downward pull on the nose (and even here
downward would mean below the glider longitudinal axis, not
necessarily below the horizon). *I'm quite sure that my ASW 28 being
towed on the CG hook has no downward force on the nose.

When I do tow in gliders with a nose hook I'm quite sure there is no
significant downward pull from the rope. *Maybe it all depends on what
you call high tow. *I've seen may pilots tow tens of feet higher than
I regard as normal high tow.

Andy

Which part don't you accept? The part about rope pulling downward, or
the part about the required lift being greater if/when it does?

In the previous discussion we all seemed to agree that the tow rope
has a consicerable sag during tow, and that the pulling force of the
rope acts in the direction of the rope meeting the tow hook, which is
not along the long. axis of the glider, and not parallel to the
direction of flight of the glider.

Now, how significant? I dunno!

With a mid-mounted wing glider and a nose hook, the forces of the tow
rope and the drag all run pretty close to the CG.....so probably
little to no pitching effect.......On a 2-33 for instance, where the
tow hook is mounted low, and the wing is high, I believe there is a
nose up pitching moment created, and in fact the 2-33 needs full
forward trim and considerable forward stick pressure on tow. Where a
mid wing nose hook glider flys nicely with about neutral trim and
little stick force if any.

But if we were to agree that the tow rope does not pull in the
dircetion of flight of the glider, and in fact pulls somewhat
"downward" compared to the direction of flight, we need to balance
this force......the only way to balance this force is for lift to
become greater, since weight, and drag remain the same. More lift
comes from more AoA.

I am not saying this is the only factor in this mushy tow deal, but I
think it contributes along with the other factors mentioned.


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