The best way to keep things straight is to divide the wing into a grid system with each "cell" getting a different amount of lead for each load case. Over 280 cells were loaded to accuracies within one pound to achieve the exact loading for each condition. The sum of the loads in each cell of our grid closely approximates the total flight load and distribution. When we test the wing, we mount it upside down in a rigid steel frame, simulating the fuselage, and cover the bottom surfaces with thin plywood, marked with this grid.


 
Loading shot bags on the bottom simulates the load the wing will see in normal flight. It takes some equipment, (ie., a forklift!) some muscle (someone else’s, if I can arrange it) and careful attention to be sure the right amount of weight is applied in the correct location.

Part 23 requires that the wing support 1.5 times the limit load of 3.8G
 (i.e.: 5.7G) for 3 seconds in all conditions. It allows the use of a different test article for each condition. We used the same test article to test for all conditions. Ours is a more severe test, because the wing could be weakened by one test before the next is run. As full load is reached, the wing creaks and groans and wrinkles run like heavy seas across the top skins. Engineers start using some strange body english and holding their lips all funny. When the last few shot bags are loaded, the atmosphere can be pretty tense.

We were very pleased to find that our calculations had been correct and the wing passed all the requirements of Part 23.

Please, watch the RVator and this website for details of RV-10 development, but don’t call and ask us how it’s going. When we know, we will let you know and we will know sooner if we spend less time on the phone.
                                
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