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Post by silverdragon on Jul 15, 2014 8:05:18 GMT
Take a bottle one third full of water, add air, with a foot pump, through a cork holder jammed in the neck, (Upside down of course?..) and the bottle will take flight.
I have a question....
My Foot-pump "says" it can do 180lbs/sq inch.
It could probably manage 100 with me pumping.... I think I would run out of pump before I went much further....
So am I in danger of over doing the pressure if the bottle fails to release?...
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Post by the light works on Jul 15, 2014 17:08:26 GMT
I suspect the bottle would fail, particularly with more modern bottles. I also suspect that being a foot pump, with - if yours are like ours, with about a 10:1 mechanical advantage on the treadle, you would have to be much more petite than I envision you to be unable to pump past 100 PSI.
however, I do not know the PSI burst strength of the average carbonated beverage bottle (which would be the strongest bottle I would expect to see) so I could be wrong.
the design I am more familiar with includes a tennis ball, and a release mechanism made with a bent rod driven through holes in the launch tube - to create a release. (I believe he also used the cap with a hole drilled in it to create a tighter rocket nozzle.)
this was submitted as a replica hand cannon for war scenarios, and was originally rejected on the grounds the rules did not allow compressed gas fired weapons - but the appeal was granted on the grounds that it was, in function, a perfect replica of a period hand cannon: cumbersome, awkward to load, wildly inaccurate, and creating a huge visual interference. - and because everybody who saw the demonstration thought it was way cool.
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Post by silverdragon on Jul 16, 2014 8:25:28 GMT
100psi I can manage, I have never got as far as 180....
"Myths you can do at home", an episode that aired recently in UK, used Water and Dry Ice.
I am using the 100psi mark as that is what they found was about the strength of a drinks bottle on the show.
Did that not air yet in USA?... Strange.
For my home-brew design, take either a nozzle from a garden water hose or any plastic pipe with a slight taper and jam it hard into the bottle opening, upside down..... that will hold it enough to get 60 to 70 psi which is normally enough to get a good flight with a water rocket.
Its simple and effective.
The harder you push it in, the more pressure, and if its a Garden hose, you can do all the pumping through a long hose...
Or... if like us... if you have enough mains water pressure, you just turn the tap on, fill to one third, and pump air the rest of the way.
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Post by the light works on Jul 16, 2014 13:41:26 GMT
100psi I can manage, I have never got as far as 180.... "Myths you can do at home", an episode that aired recently in UK, used Water and Dry Ice. I am using the 100psi mark as that is what they found was about the strength of a drinks bottle on the show. Did that not air yet in USA?... Strange. For my home-brew design, take either a nozzle from a garden water hose or any plastic pipe with a slight taper and jam it hard into the bottle opening, upside down..... that will hold it enough to get 60 to 70 psi which is normally enough to get a good flight with a water rocket. Its simple and effective. The harder you push it in, the more pressure, and if its a Garden hose, you can do all the pumping through a long hose... Or... if like us... if you have enough mains water pressure, you just turn the tap on, fill to one third, and pump air the rest of the way. is this more of a "before my leg gets tired" qualifier? I saw the episode, but I did not remember the numbers. the design I saw loaded from a bucket and dipper - and I think operated at lower pressure. my own "mains" pressure is 80 PSI. I like my showers to have some vigor. |
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Post by watcher56 on Jul 17, 2014 0:45:02 GMT
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Post by silverdragon on Jul 17, 2014 7:27:35 GMT
Exactly.
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