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Motor Mount Construction

Specifications

Component Value
Motor Tube ID 38mm
Motor Tube Length 11" (28 cm)
Centering Rings Plywood, 38mm to 98mm

Motor Retention Options

The kit does NOT include motor retention. Options:

  • AeroPack 38L for LOC-style paper tubes (OD 1.630")
  • Provides professional appearance
  • Easy motor changes
  • Epoxy to aft centering ring

Option 2: Fins & Fire Retainer

  • Alternative to AeroPack
  • Similar functionality

Option 3: Masking Tape (Traditional)

  • Wrap tape around motor at tube exit
  • Simple and effective
  • Must re-tape each flight

Shock Cord Attachment

The motor mount includes a Kevlar cord anchor:

  1. Thread Kevlar through centering ring holes
  2. Secure with epoxy
  3. Allows rear centering ring to be pulled out for internal fillet access

Long Motor Accommodation

Motor Length

The motor tube is 11" long. For motors longer than the tube:

  • Remove thrust block
  • Motor will project into parachute bay
  • Verify adequate space for recovery gear

Build Notes

Epoxy Selection

Used 1-hour epoxy (working time) with 24-hour cure.

Epoxy Viscosity Issue

The epoxy was quite liquid, which caused it to leak through small holes in the centering rings. This required careful orientation during curing.

Curing Process

Due to liquid epoxy leaking, each side was cured separately:

  1. Day 1: Motor mount positioned upright, epoxy applied to bottom centering ring area
  2. Day 2: Flipped, epoxy applied to top centering ring area
  3. Day 3: Internal fin fillets
  4. Day 4: External fin fillets

Total cure time: ~4 days for complete assembly.

Lessons Learned

  • Thicker epoxy (Rocketpoxy or thickened with microballoons) would reduce leakage
  • Pre-sealing centering ring holes with thin CA can help
  • Patience with 24-hour cure cycles results in stronger bonds

Build Photos

Photos to be added - see Issue #8