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List small or large improvments we can make to design, process, or operations.

SAC 2023

General

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

Structures

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

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)

Avionics

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

Payload

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

Recovery

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

Launch operations

  • Weigh the rocket

  • More radio training

Field recovery

  • 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

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