After our last launch we started on a campaign of further ground testing to see if we could replicate the loss of GPS location updates. We ran a half dozen cold soak tests using dry ice to drop the Tracksoar down to between -40 and -60 celsius, the usual range of temperatures we have seen at altitude. Additionally we did some real stress testing and dropped the board and batteries down to -100 celsius to see how it held up, and got some very interesting results.
Subjecting the Tracksoar to temperatures below -40 for more than a half hour caused the GPS to lose satellite lock. Pouring over the various components datasheets we found that the GPS antenna we selected (and pretty much every other GPS antenna we researched) has a rated limit of -40c after which point it will detune and no longer be able to pick up the GPS signal. This is most likely the cause of the issue we saw on our last flight where the GPS stopped updating at 66k feet, rather than the jumper issue I had suspected initially. With this new data in hand we worked on a solution and found a very simple one, by encasing the Tracksoar in EPF (Expanded Polystyrene Foam) we were able to insulate it enough to last for hours at external temperatures well below -40c. We are now working with a couple of vendors to create a custom molded EPF shell for the Tracksoar, that will serve to protect it in shipping as well as in flight.
To further test that our EPF shell will resolve our issues we have another launch planned for this Saturday 8/29 from somewhere near Castaic CA.
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