November 08, 2005

From Canaan




I finally got my sensor talking to Flightgear in real time via socket programming. If you're willing to thrash around for a while you can learn to do just about anything by studying source codes. It turned out I only had to tweak the uNav/Stargate published source codes a bit and run Flightgear on the TCP protocol (until I figure out how to shift to others? ...If it matters). First you make things work, then you make them elegant!

The output jitters a bit with about (1) degree of variation over time in heading position. I think this may be a calibration issue, but it will a while before I burrow into things and check that out. I may be getting effects from the fact that the sensor is in a cardboard box on top of the Linux box. Of course, for an extra $10,000 to $15,000 you can get a sensor that doesn't jitter... Anyhow, the uNav definitely is sensitive to iron as readily illustrated by moving a small screw driver near the device. I think I swung the compass (and the display depiction) about 15 to 20 degrees with the screwdriver. I wanted to take the picture of the device next to the monitor but nixed the idea because of the steel used in the support frame the monitor sits on. Plus I figured it probably wasn't a great ideat to get it anywhere near a flyback transformer...

Progress only cost me two lock-ups of my machine and I have some file system cleanup to do from the wreckage, but it is nice to verify that you can combine an inertial sensor with a flight simulation package and produce a sophisticated cockpit display capability.

Meanwhile, back at the ranch... Joel Godston (retired from Pratt & Whitney) gave a talk on jet engines this evening at our EAA chapter meeting. Joel brought parts! ...From his development days when they tested engines, and that occasionally meant frying them... When you think of it, the development of gas turbines over the last 50+ years has produced the most reliable and fuel efficient high output engines ever produced.