#1
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Booster question
I am building my first booster rocket with my daughter, and have a simple questions. How tight or loose should the booster section be to the main rocket? We are building a SEMROC Shrike and the booster stage seems pretty tight.
The engine hook on the main rocket needs to slide inside the engine tube of the booster, that makes a pretty tight fit. Is this okay or do I need to somehow loosen the connection? any help would be great!! thanks Phil |
#2
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I think you've got a construction problem. The upper-stage motor hook should not enter the booster stage motor mount tube.
The "classic" Estes multi-stage motor mounting technique didn't use motor hooks at all, because the motors were taped together. Later, the "pop and go" method was introduced. The motors were not taped together, and there was a small gap between the top of the booster motor and the nozzle of the sustainer. Sometimes vent holes are put in the booster to vent gas. Without knowing exactly how you put the model together I'm not sure how to correct things.
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NAR #27085 - Oregon Rocketry - SAM |
#3
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The instructions call for two hooks, one ea. for the booster and sustainer.
http://www.semroc.com/Documents/pdf/Shrike.pdf Steps 7,8, 9, 13 and step 21 establish the correct dimentions. Could you have made a mistake? |
#4
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I've just finished the booster and the upper stage. The situation is exactly as you describe. Don't worry about the tight fit tho. The booster will separate. Did you finish your Shrike and if so have you flown it yet?
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Leo My rocket fleet and more @ Leo's Leisure Site and on YouTube - My latest project: ALTDuino |
#5
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"Pretty tight" is ok. Anything more than "pretty tight" will result in the stages not separating and the sustainer firing through the booster....roasting the interstage area in the process.
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I love sanding. |
#6
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And if it is too loose, the pressure generated by the blow-through of the booster motor separates the booster without igniting the upper stage, usually resulting in the sustainer lawndarting.
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'Til next time, Mike Toelle NAR 31692 L1 SAM 0373 |
#7
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Except when using the Shrike as dual deploy which I will be doing. It's a perfect rocket for the task
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Leo My rocket fleet and more @ Leo's Leisure Site and on YouTube - My latest project: ALTDuino |
#8
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You have built the Shrike per the instructions in which the booster coupler extends about 1/2 inch above thebooster BT, and the sustainer motor tube is flush with the bottom of the BT. This places the sustainer hook about 1/4 inch into the booster. The best recommendation I can offer is that the booster should be able to turn on the sustainer with a little twisting pressure. Not loose, and surely not tight enough to stick. If it is too tight, lightly sand around the coupler. If it becomes too loose, lightly dampen the coupler prior to a flight.
Nice model. Enjoy your flights.
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Gravity is a harsh mistress SAM 002 NAR 91005 "The complexity of living is eminently favored to the simplicity of not." |
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