Mechanics, Engineers, and Heating

These two creatures work in perfect harmony at NASA's 40x80 foot Wind Tunnel, most of the time. Deny an engineer its lunch, ho-hum they'll keep working without too much of a fit. Deny a mechanic a 10-minute break every hour or a 1-hour lunch break, all hell will break loose. The lesson to learn here is that mechanics need to eat constantly or they might throw a temper tantrum.

So the wind tunnel tests. They are progressing, albeit very slowly but they are progressing. Yesterday during one of the warm up runs one of the screws on the tips of the rotor blades sheared off. There wasn't any damage done to anything else, but they had to stop testing for the day and inspect the model and replace the screw. So I had the afternoon off. Saying it was off might be slightly misleading I had the afternoon off from sitting in the control room to sitting in meetings and at my desk doing my other work. The other work is going well and its become more focused. Instead of looking entire population of the reference points, I am now just looking at the power readings from the test stand. What changed one might ask? Well as I was looking at the housekeeping points, something strange began to appear. The mean values for the backup sensor started to read a lower value at the end of the run than they were reading at the beginning of the run. They should have been reading the same, or rather within a reasonable percentage difference, but instead they were reading almost 5% lower than they were reading at the beginning of the run. So this raised the question of what the hell the sensor was up to. So without going into how a rotor balance is constructed just know that heat can cause thermal expansion which can then change the measurement of the sensors in the test stand. So now I have to find evidence of these "thermal effects" in other points besides the housekeeping points. My research may have been narrowed but this is the first time these effects have been observed so figuring the thermal effects is more important than checking if the mechanics can set up on the correct test conditions.