Uploaded August 2025 | Updated September 2026, 1 week ago
Ready to give your Mako or other 74mm (3" diameter) airframe an extra kick? In this video tutorial we walk you step-by-step through installing Apogee’s Dual 29 mm Motor Mount Adapter Kit inside a 3-fin rocket that uses through-the-wall (TTW) fins—a combo that looks simple until you realize the fin tabs don’t quite touch both motor tubes. We’ll show you how to bridge that gap, align everything perfectly, and beef it up for extra durability.
Kit used in this video:
Dual 29 mm Motor Mount Adapter Kit (29 mm → 74 mm body tube)
apogeerockets.com/Building-Supplies/Motor-Mount-Kits-Adapters/Motor-Mount-Kits-for-Body-Tubes-56mm-and-Up/Dual-Motor-Mount-Adapter-Kit-29-74
What you’ll learn:
• Dry-fitting centering rings & tubes for a dual-engine layout
• Trimming the “too-long” third fin tab so it clears the mount
• Using G/Flex 655 thickened epoxy to bridge the small fin-to-tube gaps without adding excess weight
• Forming internal fillets that become the primary load path for the fins
• Holding everything straight with a 3-fin alignment jig while the epoxy cures
• Adding the external fin fillets to finish it off
Tools & Materials
• Dual 29 mm motor mount kit
• 3-fin alignment jig
• G/Flex 655 thickened epoxy (or equivalent high-viscosity epoxy)
• Mixing sticks, epoxy brushes, nitrile gloves
• Hobby knife & sanding block
• RockSim or flight-sim software
If you found this helpful, smash that Like button, subscribe for more advanced build tips, and ring the notification bell so you never miss a launch!
Questions or additional tips to share? Drop them in the comments below—we love seeing your projects.
#ModelRockets #ClusterRockets #ApogeeRockets #RockSim #GFlex #HighPowerRocketry
Ready to give your Mako or other 74mm (3" diameter) airframe an extra kick? In this video tutorial we walk you step-by-step through installing Apogee’s Dual 29 mm Motor Mount Adapter Kit inside a 3-fin rocket that uses through-the-wall (TTW) fins—a combo that looks simple until you realize the fin tabs don’t quite touch both motor tubes. We’ll show you how to bridge that gap, align everything perfectly, and beef it up for extra durability.
Kit used in this video:
Dual 29 mm Motor Mount Adapter Kit (29 mm → 74 mm body tube)
apogeerockets.com/Building-Supplies/Motor-Mount-Kits-Adapters/Motor-Mount-Kits-for-Body-Tubes-56mm-and-Up/Dual-Motor-Mount-Adapter-Kit-29-74
What you’ll learn:
• Dry-fitting centering rings & tubes for a dual-engine layout
• Trimming the “too-long” third fin tab so it clears the mount
• Using G/Flex 655 thickened epoxy to bridge the small fin-to-tube gaps without adding excess weight
• Forming internal fillets that become the primary load path for the fins
• Holding everything straight with a 3-fin alignment jig while the epoxy cures
• Adding the external fin fillets to finish it off
Tools & Materials
• Dual 29 mm motor mount kit
• 3-fin alignment jig
• G/Flex 655 thickened epoxy (or equivalent high-viscosity epoxy)
• Mixing sticks, epoxy brushes, nitrile gloves
• Hobby knife & sanding block
• RockSim or flight-sim software
If you found this helpful, smash that Like button, subscribe for more advanced build tips, and ring the notification bell so you never miss a launch!
Questions or additional tips to share? Drop them in the comments below—we love seeing your projects.
#ModelRockets #ClusterRockets #ApogeeRockets #RockSim #GFlex #HighPowerRocketry
