List small or large improvments we can make to design, process, or operations, in reverse-chronological order.
Successes:
Test-flight timeline (even without test flight) made us do much less last-minute so IREC weeek was less stressful
Same goes for integration tests well before IREC
Failures:
Never weighed rocket
Showed up to Tuesday saftey checks without fully-assembled rocket
Mitigations & ideas:
Show up to saftey check fully assembled (sans energetics)
Weigh the rocket in the field
Assign a systems engineer
Failures:
Long tube makes assembly very hard
Tubes fill with dust when wind gusts
Weathercock off rail
Low-ish TWR
Long railguides levered and caught on rail
Winding improvements
Redesign and reprint filament holder end caps
Design a dowel/other holding system for the rollers
Mitigations & ideas:
Aim for higher TWR
Return to button rail guides
Shorter/more open tubes
Printed end caps for tubes
Make long tubes before lengths are figured out (work in parallel)
Successes:
Sleds not wired together
Crimping multiple conductors into one ferrule for bridging
Huge Big Red Bee battery
Batteries with protection circuits
T-shaped and tapered key, easy to insert and stops in the right place
Failures:
Glued nut stuck inside, could not remove avionics bay
FSR judge didn’t like the massive battery and thin sled parts
it did break during flight
Sleds were loose when not in a tube
Big Red Bees are way too unreliable for a COTS part, we’ve had 4 failures in total
BRB antenna smashed into nose cone bulkhead and could not transmit
Upper end cap broke
Mitigations & ideas:
Retain the sleds while outside a tube
Impact test avionics bay
Re-do FEA after all changes, new holes/slots mean new stress concentrations
Think about assembly forces, not just flight forces
Better nut retention on the mounting bars
Do smaller slots for wire pass or put them on the side of the sled (DO backplane sled, DON’T do COTS sled)
Reduce the number of threaded connections, labor-intensive to Loctite everything
Have spares for everything (backup Big Red Bees saved us)
Tripod for the antenna holder on the stands
Use rubber ducky (or other encased antenna) for everything sticking up
GSW tracks “time of last update” and “time of last change” for GPS packets to check lock
Successes:
Mounting electronics to side panels improved density and made assembly easier
JST connectors worked well
Good to buy batteries with protections
Failures:
Line cutter immediately got cut
Alternate: Early main due to pressure spike
Need to depanel payload in the field to plug things in
Not enough venting
Mitigations & ideas:
Put a switch on every battery
Stronger line for line cutter
Successes:
Drogue streamer is easier to integrate, easier to see on descent/recovery, less snatch force
Mini-Tamiya connectors worked and did not need to be zip tied. Very cheap and easy to use.
Failures:
Needed to reach down 5’ of tube
Main at apogee for TBD reasons
Single-bay might be more complicated than worth, but not totally clear since we had >1’ of payload
Booster coupler tube cut shock cord, load rating did not matter
Couldn’t de-integrate fully because integration testing didn’t have us threadlock the charge caps or
Mitigations & ideas:
Back to dual bay
Higher TWR for less weathercocking
Fully (dummy energetics) integration test! No exceptions
Protect potential cut points (wrap more kevlar/other protection)
Wrench flats on charge cups
Weigh the rocket
More radio training
Land navigation training
Require all recovery to be HAM licensed
Earpiece microphones
More radio training
Make sure one person has cell reception (Verizon seems reliable)
Timer to drink water