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Old 30 November 2005, 09:54   #61
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I think me brain's just come back on line. It'll be the reaction to accelerating the water not the reaction to the accelerated water.

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Doesn't have to thrust against anything - ask Newton!!!
Well Cod, since Newton is not here, could you please explain it?
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Old 30 November 2005, 09:58   #62
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Newtons 3rd law - for every action there is an equal and opposite reaction.

Way a rocket works in space - chucks mass out the back so it goes forward.
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Old 30 November 2005, 10:17   #63
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Quote:
Originally Posted by codprawn
Newtons 3rd law - for every action there is an equal and opposite reaction.

Way a rocket works in space - chucks mass out the back so it goes forward.
You don't fekkin know.
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Old 30 November 2005, 12:04   #64
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My jet unit has a large flat plate underneath about 12 x 12". If at planning speed this is level with the water surface then the jet exit water will be above the surface however it is angled down which suggests that the exit water will contact the surface about 6 - 12" further aft. Well thats what I hope it will do if I can re build it.

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Old 30 November 2005, 12:14   #65
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Quote:
Originally Posted by jwalker
You don't fekkin know.
Know what??? Thought it was SO obvious myself!!!!

Could make the joke about it hardly being rocket science but to be honest it IS - and there's nothing complicated about that either!!!
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Old 30 November 2005, 12:30   #66
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Pete.

Is there anything you have not got lying around your garden?



There must be a tea-chest full of used tenners somewhere.
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Old 30 November 2005, 12:35   #67
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Quote:
Originally Posted by Mark Halliday
Pete.

Is there anything you have not got lying around your garden?



There must be a tea-chest full of used tenners somewhere.
Sounds as bad as me - doubt I have a tea chest full of tenners though!!!
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Old 30 November 2005, 12:50   #68
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Just a thought... but I understood the most effective jet-drive was when the jet was just above or partially above the water line and pointing down/at it. I thought that if the jet was totally submerged it wasn't as effective.

I may be wrong of course, but I did pick that nugget of info up somewhere in the dim and distant, but didn't think it would ever come in handy
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Old 30 November 2005, 12:55   #69
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Quote:
Originally Posted by codprawn
Know what??? Thought it was SO obvious myself!!!!
.. - and there's nothing complicated about that either!!!
Well I'm a numpty, explain it to me.
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Old 30 November 2005, 12:56   #70
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Quote:
Originally Posted by Erin
Just a thought... but I understood the most effective jet-drive was when the jet was just above or partially above the water line and pointing down/at it. I thought that if the jet was totally submerged it wasn't as effective.
I think that you are right, but it's because a jet of water won't accelerate as much if going straight into water, whereas if it goes into air you get a bigger/better acceleration effect (Force = Mass x Acceleration) before it hits the water.

If you use a pressure washer to clean the car, it doesn't push back harder the closer you are to the car - the force all comes from the water coming out of the nozzle, not what it hits.

It's the same as the hosepipe into a bucket that Kitten mentioned earlier.

...I think...
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