ORIGINAL: hombresinropa
I want to create one of these that anchors into the soil, and the restraint flips down on a hinge, so I don't have to pull up stakes or pick up the airplane with it running. This is mostly a concern for me when I'm by myself at the field. I imagine that a gate latch would do the trick, with a couple pieces of bent wire or rebar and a spring. a bit like a mousetrap.
A few years ago I made just what your describing buy using a standard entry door hinge. However I didn't use a spring, just the mechanics of the hinge to limit travel in one direction. When I'm ready to fly I just pull the plane back a foot or so and push the restraining arms down parallel with the ground and leave them there until I need to use it again.
One caveat though, my design is all steel so it is something I welded together. I can take a pic of it and post if you would like?