Standards and Repeatability

So there is this one customer of ours who comes by the tunnel couple times a year at least. They have a "standard" test article that they bring every time and have been for at least the past 4 years. We put this test article in and set it up to the same configuration for them to judge comparability of the data from that test to previous tests on other test articles. We are talking about 250Lbs in one force and 1100Lbs in another force. Well, they came in and put the standard in and we ran the first test run of the day. The reading repeated in two runs but we were about 2 and 1o Lbs off in the two forces of interest. So they checked setup and determined that there was something that was not right with the standards setup and changed it to make it correct and ran the next two runs.

Think about that for a second, an aerodynamic test article that the test mounting system is removed and reinstalled each time and the test article that has been transported back and forth for each test and the fact that we were off 2 in 250 Lbs and 10 in 1100Lbs was found to be a setup in the test article and the numbers repeat over a 4 year period with all the setup changes. OK, maybe I'm just geeking out a bit about the repeatability of the test article considering that we see much larger differences between supposedly identical articles brought in for test.

Besides, this crew is a pleasure to work with. I wish I could say more about who they are and what they do as more people would be able to identify with them and what we are testing. Unfortunately I have to stay in generalities when talking about this particular series of tests. That's more than I can even say about others. Like last week when we tested something really cool that can't be talked about. Then we get tests in for NASA that is all public domain so we can talk about them. Just google NASA Jumbo Dart if you want to see some really cool videos of 80K pounds being pushed out of the back of a C-17 at 35K feet altitude. Can you say world record for heaviest highest drop? We had a hand in the testing that preceded that drop and have the model, CAD drawings, pictures and videos to prove it.