josepher44
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After almost 2 years away from rocketry, finally getting some free time this summer has gotten me back into it. After some work with some older LPR/MPR kits, I have decided to embark on my first scratch built HPR project since returning, in preparation for turning 18 and the possibility of Level 2 opening up.
I have designed a much modified "replacement" to a rocket i built 2 years ago, dubbed Kid Speedy. It was a stubby 5.5 inch design, with a 5 motor cluster, consisting of a central 54mm and 4 29mm outboard motors. Unfortunately, an adapter failure lead to a rather disastrous maiden flight, crushing 2/3rds of the body and causing more minor damage throughout the fin can.
Partially to work with the parts I have on hand, and partially to prevent this build from becoming a complete redo of Kid Speedy's, I have redesigned nearly all of the rocket. The motor mount is still a 5 motor cluster, this time with the central mount scaled back to 38mm. The body has been completely redesigned. The new design stands 8.5 feet tall, with most of that being 3" tube. The lower 2 feet are 4", with a fiberglass-covered foam transition in between. Since the motor mount doesn't quite fit nicely in the 4" tube, the 29mm mounts will stick out a bit through precut slots, and be "capped off" by aerodynamic foam and fiberglass end caps.
Although I am waiting for most of the parts to come in, I have been able to start construction of some parts of the rocket, namely the centering rings and adjustable noseweight system. Couple pics of that, with more to come in a bit.
Finally, I have a couple of questions.
1. Once everything is epoxied together, will the large amounts of slots being cut in the booster still be a weak point, or will the motor mount hold everything together well enough? If not, what kind of reinforcement here would you reccomend? Would this be a good project to go with a foamed fincan?
2. For ease of access/wiring, I was planning on mounting at the very least airstarting electronics, and possibly deployment electronics as well, low down in the rocket, just below the transition. Will the presence of the transition, fins, and 29mm motor mounts create enough aerodynamic disturbance that this is a bad idea, or will they be fine down there?
And some pictures:
The remains of Kid Speedy (ow...):
Rocket modeled in Autodesk Inventor:
Motor mount, minus Aft centering ring:
Pile 'o Parts:
Cluster centering rings (AKA ninja stars of death) laid out on 3/8" birch plywood:
29mm holes cut out (all cutting was done with a dremel circle cutter)
Finished ring, pre-sanding:
Enjoy! More to follow
I have designed a much modified "replacement" to a rocket i built 2 years ago, dubbed Kid Speedy. It was a stubby 5.5 inch design, with a 5 motor cluster, consisting of a central 54mm and 4 29mm outboard motors. Unfortunately, an adapter failure lead to a rather disastrous maiden flight, crushing 2/3rds of the body and causing more minor damage throughout the fin can.
Partially to work with the parts I have on hand, and partially to prevent this build from becoming a complete redo of Kid Speedy's, I have redesigned nearly all of the rocket. The motor mount is still a 5 motor cluster, this time with the central mount scaled back to 38mm. The body has been completely redesigned. The new design stands 8.5 feet tall, with most of that being 3" tube. The lower 2 feet are 4", with a fiberglass-covered foam transition in between. Since the motor mount doesn't quite fit nicely in the 4" tube, the 29mm mounts will stick out a bit through precut slots, and be "capped off" by aerodynamic foam and fiberglass end caps.
Although I am waiting for most of the parts to come in, I have been able to start construction of some parts of the rocket, namely the centering rings and adjustable noseweight system. Couple pics of that, with more to come in a bit.
Finally, I have a couple of questions.
1. Once everything is epoxied together, will the large amounts of slots being cut in the booster still be a weak point, or will the motor mount hold everything together well enough? If not, what kind of reinforcement here would you reccomend? Would this be a good project to go with a foamed fincan?
2. For ease of access/wiring, I was planning on mounting at the very least airstarting electronics, and possibly deployment electronics as well, low down in the rocket, just below the transition. Will the presence of the transition, fins, and 29mm motor mounts create enough aerodynamic disturbance that this is a bad idea, or will they be fine down there?
And some pictures:
The remains of Kid Speedy (ow...):
Rocket modeled in Autodesk Inventor:
Motor mount, minus Aft centering ring:
Pile 'o Parts:
Cluster centering rings (AKA ninja stars of death) laid out on 3/8" birch plywood:
29mm holes cut out (all cutting was done with a dremel circle cutter)
Finished ring, pre-sanding:
Enjoy! More to follow