ronhill
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Thought I start a rack rocket thread and post a photo of my latest, Rack 4. Rokitflite and I accidentally hijacked a thread some time back originally dealing with tube-finned rockets.
This photo does not show the engines installed, but imagine the booster hanging in the middle of the fin booms and taped (the usual method) to the upper stage engine. This is a BT-60 design and uses a combination of D12-0 and D12-7 engines. It flew well at the Quark launch last Sunday.
The Rack 4 is not an optimum design, but I recycled the body tube from a previous conventional rocket with warped fins--too much water in the FnF on old dry plywood. I simply cut and ground off the old warped fins and attached the fin booms.
Im not sure of the definition of a rack rocket, but this definition will do. Its a multistage rocket with only one set of fins. Those fins are extended aft on booms to ensure stability for all stages. The booster(s) are CHAD staged and simply drop off (without fins) through the middle of the fin booms. The obvious advantage is decreased weight and drag during the booster phase. But thats compensated for by the weight and drag of the booms. Further, the upper stage carries everything (except the booster engine) the entire flight. Another positive factor is that the fins can be relatively small because of forward CG and aft CP.
In any case, it stages high and smoothly, and the upper stage consistently goes almost out of sightI always use a streamer. The rack rocket idea came from a 2002 TRA paper entitled, The Rack Rocket Concept, a Quest for High Altitude, by Ken Good. You can get it from his page at:
members.tripod.com/Tripoli_Rocketry_PGH/kjgboard.html
If anyone is interested, I can post photos of the since-departed Rack 1 and Rack 2 rockets or refer you to previous posts.
Is anyone else making rack rockets?
This photo does not show the engines installed, but imagine the booster hanging in the middle of the fin booms and taped (the usual method) to the upper stage engine. This is a BT-60 design and uses a combination of D12-0 and D12-7 engines. It flew well at the Quark launch last Sunday.
The Rack 4 is not an optimum design, but I recycled the body tube from a previous conventional rocket with warped fins--too much water in the FnF on old dry plywood. I simply cut and ground off the old warped fins and attached the fin booms.
Im not sure of the definition of a rack rocket, but this definition will do. Its a multistage rocket with only one set of fins. Those fins are extended aft on booms to ensure stability for all stages. The booster(s) are CHAD staged and simply drop off (without fins) through the middle of the fin booms. The obvious advantage is decreased weight and drag during the booster phase. But thats compensated for by the weight and drag of the booms. Further, the upper stage carries everything (except the booster engine) the entire flight. Another positive factor is that the fins can be relatively small because of forward CG and aft CP.
In any case, it stages high and smoothly, and the upper stage consistently goes almost out of sightI always use a streamer. The rack rocket idea came from a 2002 TRA paper entitled, The Rack Rocket Concept, a Quest for High Altitude, by Ken Good. You can get it from his page at:
members.tripod.com/Tripoli_Rocketry_PGH/kjgboard.html
If anyone is interested, I can post photos of the since-departed Rack 1 and Rack 2 rockets or refer you to previous posts.
Is anyone else making rack rockets?
Sorry Ron, I shoul dhave followed the link originally!
