Sunday, April 16, 2017

Thoughts about load testing

Various forums online are for or against a load test.  It is my understanding that every single home-built aircraft in Europe must pass a load test prior to getting approval to fly, and those airplanes aren't crashing because of the test.  And a well-managed test to a load condition within the expected operating range should do no more harm than flying normally.  I'd MUCH rather something break or deform on the ground where I have a chance of catching and correcting the error, versus in-flight.  Practically, there are enough Goats flying (ten?) to give some reasonable confidence in the structural design.  But, and I have to keep telling myself this, it's such inexpensive insurance.

For the positive load test, I will be using some heavy-duty sling straps looped around the nose top tube structure where the seat attaches, simulating my body mass being the load.  These straps will be set up to hold the assembled nose and wing sections at a slight angle to simulate an angle of attack.  And then a series of jugs of water will be split along the leading and trailing edge spar tubes and hung using string or maybe bent coat-hangers.  Hanging weights will get more definition after building the hanging rig.

Available to me (four hours away) is an old wooden swing set with plenty of structural margin to hold the mass and plenty of height too.  It's a lot of work to haul Goat that far, and back again.  Or, it's a lot of work to build a big and temporary test rig in the backyard.  I'm torn.  It'll probably be easier to build a copy of the swing set gantry in the back yard here.  Maybe I can give it to a colleague with a youngster afterwards...

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