Am 17.10.2011 18:59, Andy wrote:
On Oct 16, 12:58 pm, Peter wrote:

A rough graphical calculation that I just did shows that the Tost CG
hook will probably release at about 100 ft height above ground, perhaps
even earlier, depending on the climb angle.


That answer does not seem reasonable since it implies a limiting cable
angle of 30 degrees to the horizontal. Anyone who has observed a
winch launch knows the normal cable angle at top of the launch greatly
exceeds 30 degrees. If the limiting cable angle is conservatively
assumed to be 60 degrees then a 200ft rope would give 173 ft of
altitude if the climb profile was flown correctly.

Andy

You have to add the rope angle and the plane angle (measured against the
ground), the resulting angle is the angle between the rope and the
plane. The shorter the rope, the earlier you get to a resulting angle
that gets near 90°. Typically, a Tost hook will release a bit earlier
than 90°.

In a typical winch launch, with rope length more than 2000 ft at the
beginning, and more than 1000ft at the end of the launch, increasing the
angle of the plane does not release the Tost hook in the climb phase,
because the rope angle is much smaller than in the 200ft example that we
have here.
--
Peter Scholz
ASW24 JE