Thanks Charlie. I was a bit surprised by a couple of people that didn't think a load test was necessary. The CFI that taught me to fly asked me if I was planning on having a parachute. When I said es he said do a normal flight test then "try to break the wings off". I figured he had to be kidding and I finally told him I wasn't willing to bet my life on a parachute. I bought a light sport plane kit and the designer of it told me because my spar was basically a copy of a proven design (Marske's Monarch) he thought it was unnecessary. Maybe I'm just getting older but it seemed like the prudent thing to do. It would have been a bad day if the wings had broken, but I would rather be standing on the ground watching it rather than sitting in it watching the wing flutter away....
I have everything covered now and about 75% painted. Should be done just in time for winter to arrive and soaring season gone...
From: Charlie Johnson <This email address is being protected from spambots. You need JavaScript enabled to view it.>
To: "This email address is being protected from spambots. You need JavaScript enabled to view it." <This email address is being protected from spambots. You need JavaScript enabled to view it.>
Sent: Tuesday, September 18, 2012 9:33 AM
Subject: Re: [Carbondragonbuildersandpilots] Load test
Rick,
Well, to just go fly a new design wing spar is not an experiment it is a crap shoot. Proof loading is ok if done right as you did. Now the results of the experiment is the wing will hold 5G static. Now a wing of your design will not have to be proof loaded. You will also feel a lot better on that first flight where you introduce all kinds of asymmetrical loads into the structure.
You are making great progress!
Charlie Johnson
Ogden Utah
Sent from my iPad
On Sep 17, 2012, at 3:15 PM, "Rick" <mailto:flyndude%40yahoo.com> wrote:
> I finally got my load test out of the way. I had several people tell me they thought it was an unnecessary stressing of the wings, but a lot of these construction techniques were new to me as well as working with composites, and my wing was not constructed exactly like any other CDs that I was aware of. I wouldn't have felt at ease flying it without a test. My plan was to test it to 5 Gs but when calculating the necessary weight I forgot to subtract the weight of the wings so I loaded about 400 pounds more than I needed to. The test went well with really no noises other than occasional "bonks" as the leading edge oil-canned as the wings bowed down. At least until we got a crap-the pants "bang" toward the end. After several anxious minutes we found a screw had sheared off a diagonal brace on our test stand. Everything returned to normal after the load was removed and if I ever built another I wouldn't do the test. I uploaded a couple pictures to my photo section.
