BobCox
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I am currently building a BT-70 rocket with a 3x24mm cluster mount.
Constraints:
Option A: Make the engine tube 3.75 inches long, install a 1/4" engine block in each tube, and leave 0.5 inches of threaded rod sticking out. Install three 1-inch spacers in the tubes when using the shorter C11 or D12 engines
Pros:
+ Moves weight farther forward when using E9 engines.
+ Less threaded rod weight.
Cons:
- Spacers adds extra weight when using the lower-powered engines.
Option B: Make the engine tubes 2.75 inches long, install a 1/4" engine block in each tube, and leave 1.5 inches of threaded rod sticking out.
Pros:
+ No spacer tubes required for shorter engines.
Cons: The extra length of metal rod hanging out the back:
- may get bent on landing
- may impale something or someone during landing
- may get gunked up by the engine exhaust.
Option C: Other.
Comments? Suggestions?
Constraints:
- I do not trust friction fit. For motor retention, I want to leave a threaded rod sticking out the back between the engine tubes and hold the motors in place with nuts and possibly washers.
- I want the option to be able to fly with C11, D12, or E9 motors.
- I am trying to hold the weight down, at least on the C motors.
Option A: Make the engine tube 3.75 inches long, install a 1/4" engine block in each tube, and leave 0.5 inches of threaded rod sticking out. Install three 1-inch spacers in the tubes when using the shorter C11 or D12 engines
Pros:
+ Moves weight farther forward when using E9 engines.
+ Less threaded rod weight.
Cons:
- Spacers adds extra weight when using the lower-powered engines.
Option B: Make the engine tubes 2.75 inches long, install a 1/4" engine block in each tube, and leave 1.5 inches of threaded rod sticking out.
Pros:
+ No spacer tubes required for shorter engines.
Cons: The extra length of metal rod hanging out the back:
- may get bent on landing
- may impale something or someone during landing
- may get gunked up by the engine exhaust.
Option C: Other.
Comments? Suggestions?