On Apr 13, 11:00 am, "Bill Daniels" bildan@comcast-dot-net wrote:

snip

If the STC for a tow hook doesn't require new performance charts,
it should.

I don't believe that there would ever be another tow hook approved in
the US, if this was required by the FAA. The amount of testing and
analysis that would be required would break any club's budget.

I think charts would have to be
developed empirically from tests on a specific tug but once there were a few
data points, interpolation should be possible.

Interpolation (between data points ) or extrapolation (beyond the data
set ) ?

Interpolation to a different tug ? or to a different glider ?

You might be able to extrapolate to different gliders, but different
tugs could be vastly different, even if they were similar in major
specifications ( ie same horsepower, weight and wing loading). A
different prop size or having a constant speed prop would make a great
difference, for example.

If I had a specific tug in mind, I might come up with different tables
for single seat glass (with and without water), 2 seat glass and 2
seat trainer.

But I think it would take many-many flights to gather the data.

Todd Smith
3S