AnswerID: 237594 Submitted: Thursday, May 03, 2007 at 07:59
Member - Oldplodder (QLD)
replied:
Do the bottle rockets at the local school fete every year.
Generally get 20 to 30 metres with a 1 litre soft drink bottle.
The kids use hand pumps though.
The secret is to pump slowly and steadily until it goes.
For the cork, we put an old tyre valve stem through a rubber cork, and push the cork into a 1 litre soft drink bottle.
1 to 2 cups of water gets the best result.
Too much water and the intial acceleration is less.
Harder you push the cork in the further it goes once it lets go.
(Little secret, great fun when the littlest kid there gets an extra push on the cork, and all the bigger kids get beaten :o), tis a pleasure to see the smile of success at beating all the others , the ones who normally beat the little kids at most things.)
1 litre bottles go further than 2 litre bottles, less air resistance, since the bottles fly 2/3rds of the distance empty.
Yes, when we made up the rockets, my mate and I had to, in the name of experimentation, fly rockets all afternoon to find the best combination.
The wives just called us big kids and left us to it.
So the answer is, the size of the pump doesn't make any difference, if anything, the slowest one may produce the best distance.
Watching the pressure guage, it is hard to find a cork in the soft drink bottle that will go much beyond 50 psi before letting go. Found rubber corks worked the best.
Now, of course you will need to build a rig and experiment to prove me wrong!
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| John C - aka Oldplodder
In touring mode, the way it should be. |
Reply 5 of 6
