Bob Kuykendall wrote:

The problem as I see it with self-latching canopies on modern
sailplanes has several quite thorny aspects, and I have no intention
of going there.

The key to the problem is the activation impulse required to activate
self engaging latches: the slam.

As a first experiment, I'd suggest you go buy an ASW-27, remove the
gas spring from the canopy pivot mechanism, and then spam the canopy
closed several hundred times. Please report your findings in this
forum.

On my ASH 26 E, the gas spring and the weight of the canopy supply a
noticeable closing force when the canopy is held open a few inches. I
think this would be plenty to engage a simple latch that would keep the
canopy from opening in flight. By "opening", I mean it might allow the
rear edge of the canopy to rise an inch or two, but no more. The usual
latches would still be used to secure it closed.

In fact, the "Roeger hook" mechanism it has already works like this.
It's two small springs in the fuslage that the spike on the canopy
engage as it is lowered the last 10 mm or so. I don't think the canopy
needs to be totally self-latching, as a partial latch that keeps the
canopy from flying completely open would be a big improvement. It would
pop up and inch or two during tow, alerting the pilot to the situation
without causing him a problem. He could release and land, or perhaps
simply push it closed after releasing from a normal tow.


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Eric Greenwell
Washington State
USA