Weird Altimeter Problem

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Addicted to APCP
Jan 19, 2009
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Last weekend, I used a Perfectflite MAWD for controlling deployment in my rockets.

On Saturday, I launched my Motoreater on a K550. Deployment and recovery were normal, the altimeter was beeping out 4031 feet on recovery. That evening, I downloaded the data to my laptop. Everything was normal - until the results came up on the screen. The peak altitude was only 1700 feet. Looking back, this was the data from the previous flight of the altimeter (in August - Cyclotron on I200).

I thought this was a fluke and flew the altimeter again in my Cyclotron on an I300. Due to error on my part, the rocket suffered an extremely hard landing (RIP). However, the altimeter checked out OK. I then flew it in my upscale Deuce on J420's. Again, deployment and recovery were nominal. This time the altimeter was beeping out 2032 feet. Downloading proved that the August data was still there.

Any explanation?
This altimeter had given 6 previous flights with good data downloads before this.
Sounds like the memory chip or more likely one of the connections to it is damaged. The altimeter will beep the correct altitude as that is held in the processor chip whilst power is applied. The flight data is held on a separate memory chip - damage could prevent the flight data being recorded to this chip but still allow the data that is in it to be recalled.

You could try getting the altimeter checked out and repaired by John Fleischer - mail him at [email protected]. I have never used him (living in the UK) but I have spoken to him via e-mail and he has mailed stuff to me snail mail at his expense. He seems a very knowledgable and genuine guy. From his posts on ROL he is cheap too.
After rereading the manual to eliminate the possible of a procedural mistake, the first thing I would do is to e-mail Prefectflite, the manufacturer. They have made a lot of these altimeters and I'm sure they can help you.

It's possible that the program code got messed up in the crash. I believe you can reload the program into the altimeter as well via the RS-232.

Bob Krech
Speaking as a PerfectFlite dealer. I agree with the sound advice Bob gave. Contact PerfectFlite. Peter will help you.

It's hard to guess at what could have happened without knowing the electronics involved. Also I'm a little confused. It sounds like it the failure was intermittent and it is working now? I assume the memory is integral to the processor?
Originally posted by rstaff3
I assume the memory is integral to the processor?

No - the flight data memory is separate from the processor memory. I haven't poked around enough to know what processor and memory chips it uses (betting on a PIC of some sort and a serial EEPROM)
Lots of possibilities for soft failures. I still don't fully understand the problem.

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