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Sprint - Test Flight 2 - Raw Footage (Patreon)

Published:

2020-03-18 19:49:57

Imported:

2026-06

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Hey Patrons, lots of footage here for ya! I'll have a full edit up on the BPS channel in a while but you get the first look - so I've got a few notes!

We waited a little too long to launch last night and we missed the sweet spot of daylight vs motor/pad lighting brightness. We had one failed ignition attempt before the launch which cost a few minutes, but next time we'll go for launch a little earlier. We also set up too close to the launch site and I did a pretty poor job of tracking the vehicle on the way up, gotta practice more before the next flight!

As for the flight itself, that wiggle from last time is gone! The control system response is rock(et) solid here. The big difference was updating my Simulink model of the rocket to reflect how fast the TVC servos can move - by delaying their response a bit more, I could A, recreate the wiggle of the first flight in the sim, and B, generate much more appropriate control gains to keep the rocket on course.

I also added an integral term to the control system, which seems to do a pretty good job nulling out the initial TVC misalignment that you see at liftoff. Still some work to be done there, but glad it worked as well as it did.

The reaction wheel had a 90 degree roll programmed into it at T+1 second, and that worked quite well! We did saturate the wheel around burnout though, which means we ran out of available momentum we could dump into it from the rocket. I intentionally left the inertia of the wheel unchanged from last time to see if we could saturate it, and frankly even when we have no more roll control authority, it's still fairly stable! You can hear the wheel spin down after apogee, which is pretty cool.

As I type this, I've got new parts printing for one more flight on an Apogee F10, maybe later this week. I'd like to do one more before moving to the G8 to see if I can get better response from the integrator part of the control system.

Anyway, that's all for now! Let me know if you have any questions, and thanks again for your support!

Blue skies,

Joe

Files

Previews only

Sprint - Test Flight 2 - Raw Footage

We lost a lot of daylight after the first ignition attempt failed - should've pushed to launch about 10 min earlier. Luckily we've still got plenty of flight data! For this flight, I tried to track the rocket by "punching in" on the video camera's display in order to get better focus during flight. This backfired pretty hard when I lost track of it at the beginning of flight - it was worth a shot but I probably won't do it again :) We also lost the motor on the field - given all the footage, next time we're out there I should be able to find it so we don't litter. There wasn't enough positive motor retention force in the mount so it just slipped out on chute inflation. I think we'll do one more flight on an Apogee F10 before we move to the G8.