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Monday, April 12, 2004
Armadillo Aerospace News: Up in the air (sort of), Jet vanes, Big Engine V2.0
The thermocouple amplifiers still didn’t arrive. Axiomatic said they would ship next-day delivery on Wednesday, but when I called on Friday looking for a tracking number, no one was answering the phones. They have now missed both their quoted ship date and their verbal ship date. I went with their product because they offered 12V power and a decent case, but I am probably going to look elsewhere for the next batch.
We did a careful valve cracking calibration of all the vehicle valves. We had done this before, but I had botched the correction code, and we weren’t all that precise. To make a better check than just listening for gas escaping the nozzles, we stretched disposable gloves over all the nozzles and watched for when they started to inflate. This worked very well. There were two correction factors that the code applied to the throttle position that I wound up removing: the A/D raw to native conversion nudged the potentiometer range in a percent on each side so that the values would stay truly in the 0% to 100% range even with some noise, and the flight control software scaled the desired throttle by 70% so it would never be in the nearly fully open ball valve range with little authority. I removed both of these (I limit the controlled throttle explicitly now instead of implicitly), and now the cracking points are all at approximately the same level we see on the test stand data feedback. The individual valves cracked at different points ranging from 11% to 15% before correction, which obviously makes them not warm up the same at low throttle levels. With correction, they all crack at 11%. Read More
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