Tow testing 2: March 7 2025

• Test location: Minute Man Airfield
• Configuration:
  • Parachute connected to the car, bag connected to a long line staked to the ground
  • Reefing line cutter wire activated by flight computer
• Media https://drive.google.com/drive/folders/1heDDfimlsCK1b6wlfXEJbvaHoiqo076k?usp=drive_link
• Tow Test Procedure: Tow Testing SOP (1).pdf

• Run 1:
  • Original arrangement (cutter wire to its own rope free of the parachute lines)
  • Parachute came out of bag very tangled, did not inflate behind the car
    • We did not repack the parachute before this test and so the tangling was likely due to poor packing
  • Line cutters ignited and cut the reefing line but the parachute still did not inflate
  • After removing from the car the parachute was made to inflate by holding it in the wind
    • This makes us suspect that the car wake is affecting parachute inflation
  • Staked out line was limp and did not seem to have been pulled taut, seems like the parachute just fell out of the bag
    • Rubber band of bag was snapped
• Run 2:
  • Ensured that all reefing lines ran through the loops under the shroud lines
  • Attached the reefing cutter wire to a shroud line
  • Parachute still did not inflate in drogue or main configuration
  • Staked out line was limp again
  • Line cutters did not ignite but were ignited after the test, which seems like it was a connection to flight computer problem

Tow testing 3: March 21 2025

• Test location: Minute Man Airfield
• Configuration:
  • Parachute connected to test rig attached to car to raise the parachute up higher, out of the car wake
  • Prototype test rig:
    • 
• New tow test acceleration method:
  • For an automatic clutch (and because these tests are on tarmac now), put the car into drive and step on the brake
  • Rev the engine to 3-4k rpm (maximum power band for most engines) during countdown
  • At the same time, floor the gas pedal and release the brakes
  • Ideally this gets a faster start because the car can apply more power at the start and accelerate better, as opposed to starting from 0 RPM and revving higher before hitting max power
• Run 1:
  • Proving test rig, full parachute deployment from bag but no reefing line
  • Got up to approximately 50 mph before the line ran out, parachute came out of the bag as expected
  • Shock force of full parachute at 50 mph was enough to deform the test stand and loosen the fixture to the truck
  • VIDEO: towtest21mar_run1.MOV
  • 
  • Test was halted immediately, no damage was noted to the parachute or the truck
• Run 2:
  • Modifying test rig, ran a ratchet strap across the truck bed and then connected the (not reefed) parachute lines to that ratchet strap and up over the tailgate
  • Again, got up to approximately 50 mph before deployment, this time the shock force also immediately snapped the ratchet strap (rated to 500 lbf)
  • VIDEO: towtest21mar_run2.MOV
  • Test was halted immediately, no damage was noted to the parachute but the hooks in the truck bed were slightly deformed 
• Run 3:
  • Instead of testing parachute deployment at high speed, test the reefed parachute at low speed
  • Drive at about 20 mph (fast enough to inflate the parachute but no faster)
  • Attempted to ignite the line cutter remotely using a laptop and the telemega (did not succeed)
  • Also did not manage to ignite the line cutter with a lipo battery (so some continuity issues with the e-matches in the line cutter)
• Results:
  • Tow testing successful! Parachute emerged from the parachute bag with no issues
  • If we run tow testing again with a test rig like this, we will need to do more calculations to build a sturdier test stand