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Post by Bruce on Apr 11, 2008 18:13:43 GMT 12
O.K. I'm getting nervous!.... This Saturday morning I will be carrying out the all - important wing load demonstration on my homebuilt Adventurer. The LH wing panel (the one I havent covered yet) will be mounted upside down in a special jig, and approx 1.4 Tonnes of cement bags will be carefully loaded in increments on it.... This will demonstrate its capability of withstanding a minimum of 3.8 G (Normal category plus safety margin). Its not necessary pleasant, but worth doing. Interestingly in an anomaly in the CAA rules, Special category "experimental" or "Amateur Built" aircraft such as mine are not actualy obliged to have a wing load test, whereas class 2 (2 Seat) microlights are. Common sense suggests it is worth doing! I have a bunch of SAA mates coming along to stack cement for me  and plenty of photos will be taken (some to be posted here) - its a big day for me. I am confident that the wing will handle the load OK, but still theres always a number of things that can go wrong  Fingers crossed.... |
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Post by Dave Homewood on Apr 11, 2008 18:28:52 GMT 12
Good luck Bruce.
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Post by corsair67 on Apr 11, 2008 18:47:38 GMT 12
Yep, good luck, Bruce. I'm sure all will go well for you.
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Post by Citabria on Apr 12, 2008 8:48:50 GMT 12
Good luck mate.... hope all goes well and can you make me a concrete pot when you have finished ;D
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Post by Bruce on Apr 12, 2008 16:25:00 GMT 12
GOOD NEWS. the wing has sucessfully been demonstrated to no less than 4G - a total of 1.5 Tonne spread across the wing.  This should provide an operation limitation of +3 - 2 G with 25% demonstrated safety factor. 1.5Tonne is a LOT of cement - the wing did visibly bend,(as expected) but no structural damage ensued and everything returned to the correct shape afterwards. Heart rate and blood pressure of builder also returned to normal shortly afterwards! The only heart stopping moment was just as we were loading up over 3G, one of the dynabolts holding the jig to the floor sheared.  No damage to the wing, but a loud bang gets everyones attention. fixed the jig after sending a helper down the road to get some bigger dynabolts and wedging in an extra brace, and the tests resumed. The "empty" test rig - 90kg of plywood on the lower suface directs the load to the spars, Heavy duty cable puller attached to the portal truss to lift the wing. Mike Tunnicliffe (Mosquito builder and SAA mate taking baseline measurements  1G loading  Paul Parsons records the data  the biggie - 4G - 1500Kg! (it should NEVER get to this load again - ever...)  The fixed camera shot shows some deflection - the reflective tape is the measurement datum.  Rear spar at 4G - another fixed camera  The load was then eased to max service 3G, and another 120KG added along the trailing edge (production sandbags) to simulate flap and aileron loads - Mike measures the deflection again    After that the cement was unloaded and re-stacked on the pallet for return to Mitre 10 (who kindly loaned it for the day) No permanent distortion found - but I am so glad I dont have to do that again - in some respects the first flight will be easy after this (there was a very real risk of something breaking...) the other good news is that CAA have waived the undercarriage drop test requirement due to the fact the leg assembly and the axle / wheel sets exceed the requirements and are built by reputable commercial suppliers (Same company builds Maule UC legs) Time to have a breather this afternoon.....
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Post by Radialicious on Apr 12, 2008 16:37:44 GMT 12
...and a beer! Well done Bruce.
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Post by stu on Apr 12, 2008 17:35:05 GMT 12
You'll have to let us know when the first flight is due, could be a good excuse for another Hamilton gathering (?).
;D
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Post by Gavin Conroy on Apr 12, 2008 18:15:48 GMT 12
Well done indeed Bruce and thank you very much for illustrating things so well for us all to see, very interesting indeed |
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Post by flyjoe180 on Apr 12, 2008 21:26:58 GMT 12
Yes I found that very interesting also, cheers. I was going to ask what you were going to do with so much cement!
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Post by corsair67 on Apr 12, 2008 21:36:29 GMT 12
Yep, well done, Bruce. Great photos, and thanks for posting them here. Makes it easier for us novices to understand what's entailed in these kinds of tests.
That really is a hell of a lot of cement, and it is very good of Mitre 10 to loan you all those bags of cement, as that's a few dollars worth there.
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Post by Peter Lewis on Apr 13, 2008 19:42:16 GMT 12
Awesome Bruce, oh the relief that it all measured up.
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and plenty of photos will be taken (some to be posted here) - its a big day for me. I am confident that the wing will handle the load OK, but still theres always a number of things that can go wrong 
Fingers crossed....
No damage to the wing, but a loud bang gets everyones attention. fixed the jig after sending a helper down the road to get some bigger dynabolts and wedging in an extra brace, and the tests resumed.
