2-stage flight this weekend

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SparkyVTFlyer

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Got a 2-stage high-power flight in this weekend and I figured I'd share the video. First 2-stage flight in 2 years felt really good after I crashed the booster (I'm a slow builder). Great weather at Tripoli Central VA, 7400ft up and it landed about 1000ft away. Motors were 38mm, EX J450 Blue staging to an EX I120 Blue moonburn. Avionics were my own home-brew system that controlled all the events. The gyro did a fair job, but lost accuracy towards the end. Probably a calibration issue. 915MHz FHSS telemetry worked well, and was really useful figuring out what was happening when we couldn't see it. I was surprised how well the GPS kept up. The system is a work in progress. The plots at the end were produced with Python matplotlib.


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SparkyVTFlyer

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Thanks. Yours is pretty good too, especially your ground station; that's a thing of beauty. Mine is just a 20x4 character LCD.

I've got a newer version now with better sensors and an SMA connector, but its the same basic footprint. The software is a work in progress, and I'm constantly chasing bugs, but the core features are stable. The integrated GPS is working really well now.

I'm very happy with the magnet activation capability, which I coded with 2-stagers in mind. I can power the system and receive an audible continuity report while the system is still in "safe mode." If everything is OK, I then install the igniter and place it on the stack. It stays in "safe mode" until it senses that the magnet is nearby, then it goes through the normal startup sequence. It can sense the magnet up to about 6 inches away. Once it boots up, if you need to take it down, then just put the magnet nearby again. It will stop and go into "safe mode" until the power is cycled. It really reduces my stress at the pad when launching multi-stagers. I'm not sure if any of the other major systems have something like that. I think that some of them have gone with remote arming/dis-arming, but I like the simplicity of a magnet.


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SparkyVTFlyer

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Originally I had diodes to prevent any backwards flow to the MOSFET gate. However I found it was unnecessary. The resistors alone are enough. You can see the difference between the photos of the two designs. Keep in mind, I’m no professional and do this work as a hobby.
 
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