Life glider hours with winch

Hi Bob.

Thanks for the reply, it was what I looking for !!

I think that the pilots how said that, were thinking that because the 3.52 g that the glider "suffer" during the wich start.

Have a nice day, José


El jueves, 21 de marzo de 2019, 23:02:51 (UTC-3), Bob Kuykendall escribió:
What I've read is that the bending forces applied to the wings and tail during a typical winch launch are roughly equivalent to 3.5g flight. That is comfortably below the load limit of every common glider. However, it is high enough that repeated launches will eventually shorten the service life of an aluminum glider. The Blanik designers understood this very well, and the original service documentation was quite explicit about logging operations carefully so the service life could be tracked. Unfortunately, most operators did not do so.

Normal winching operations probably has no appreciable effect on the composite parts of a composite glider. However, I believe it was BGA analysis of repeated winch launch stresses that initiated the service bulletin on the steel end-pins ("spigots") on Grob 102, 103 and 109 series sailplanes.

As for wood sailplanes, my concern would mostly be around the age and condition of the structure, since many wood gliders are now half a century old.. Since you don't feel the added stresses of winch launching the way you feel the g of vertical acceleration, it would be easy to get into the gray area between what the structure was originally built to sustain, and what it can actually sustain after fifty years of operation, repairs, and deterioration.

--Bob K.