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Q & A: bottle rockets

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Most recent answer: 04/13/2015
Q:
Me and my friends are competing in a bottle rocket competition. We decided to model our rocket off of a harpoon missile(sorry I can't attach a picture, but please look it up). Is this a good design? Our rocket consists of 6 2 liter bottles and 3 1 liter boosters by the way. And also how much should we fill our rocket?
- Purush (age 13)
Cali
A:

We have many old answers about bottle rockets, easy to find with our search engine. They answer the questions about optimal filling and fins.

What's different about your question is that you propose using boosters. I'm puzzled about why you would have 3 L net boosters for 12 L net second-stage. The boosters will do very little to lift that big weight. You should use big boosters for a small second stage. That way the boosters can go almost as high as they would without having to carry a second stage, and the second stage can then add more height to that. What made you think of doing it the opposite way?

Our old answers discuss the question of using multiple bottles for a single stage (like your second stage). We see very little advantage of using multiple bottles. So I think you want a small single-bottle second stage with a booster of multiple large bottles.

One tough part  will be to get the multiple booster rockets started at the same time. Then the big trick will be to trigger the second stage at the highest point in the boost. What are your plans for that?

Mike W.

 


(published on 04/13/2015)

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