Compressor question

Submitted: Wednesday, May 02, 2007 at 20:13
ThreadID: 45025 Views:1802 Replies:6 FollowUps:9
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The options are: ARB, Bluetongue, Bushranger, Big Red and the list goes on .... which compressor will push these water rockets the furtherest ?? A bit of fun in the bush ... just don't camp too far from the hospital in case they get out of control or blow up. Not sure if they would be rated to 100-200 psi.

Water Rocket

Exploroz and the post originator take no responsibility for personal injury! But they look like so much fun!

Wazza.
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Reply By: Member - Olcoolone (SA) - Wednesday, May 02, 2007 at 20:15

Wednesday, May 02, 2007 at 20:15
explosives work better!

Regards Richard
AnswerID: 237498

Reply By: Member - Sam (NSW) - Wednesday, May 02, 2007 at 20:25

Wednesday, May 02, 2007 at 20:25
you can easily make a similar rocket out of a P.E.T. bottle and the valve cut out of a bicyle tyre inner tube.

take an old inner tube and cut out the valve stem, leaving a bit of the tube around the base (you need this to help make the seal)

cut a hole in the screw on cap of the P.E.T. bottle big enough for the valve stem to fit through, put a bit of silicone between the rubber and the cap to make a decent seal.

fill the bottle with 1/8th of water, screw the cap on and hook up a bike pump. Pump it up as hard as possible and then detach from the pump and slowly unscrew the cap, making sure you point it away from your body and not at anyone else.

the bottle should shoot up into the air to a reasonable height.
AnswerID: 237500

Follow Up By: Wazza - (Vic) - Wednesday, May 02, 2007 at 20:29

Wednesday, May 02, 2007 at 20:29
Sam,

damned if I could get the bugger to go straight though.

Wazza.
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FollowupID: 498528

Follow Up By: Member - Sam (NSW) - Wednesday, May 02, 2007 at 20:35

Wednesday, May 02, 2007 at 20:35
Yeah, thats the one down side.

But that has a lot to do with the propulsion nozzle. If you could control that a bit better, might have a better chance of getting it to go straight.

But I have never been able to have a direct vertical launch using water. LPG is a different story ;-)
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Follow Up By: Crackles - Wednesday, May 02, 2007 at 22:57

Wednesday, May 02, 2007 at 22:57
Unscrewing the bottle sound like a good way to get wet Sam.
We've gone a bit more high tech with our PET bottles glueing 3 fins to the neck of a 2 litre Coke bottle & a heavy washer & nose cone to the base to help it fly straight. The launch pad is a water hose connected to the tap with a one way valve & tee piece connected to the compressor. A poly hose of the exact diameter seals perfectly into the neck of the bottle. To launch I just turn on the water tap to 1/2 fill the bottle then turn on the compresor. At around 100 psi it shoots off up to 50 metres. Next project (For the Kids) is to shoot a drink fountain bottle off which I've be told are good for over 150 psi :-))
Cheers Craig................
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FollowupID: 498602

Follow Up By: Member - Sam (NSW) - Thursday, May 03, 2007 at 07:46

Thursday, May 03, 2007 at 07:46
It is! Ok on a hot summers day, but not so much fun when the weather is a little cooler.

I might have to have a crack at doing what you have done Craig. Sounds good to me!
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Reply By: Bonz (Vic) - Wednesday, May 02, 2007 at 20:30

Wednesday, May 02, 2007 at 20:30
I need one, lets get a cartel together and order many at a reduced price.
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AnswerID: 237506

Follow Up By: Member - Sam (NSW) - Wednesday, May 02, 2007 at 20:33

Wednesday, May 02, 2007 at 20:33
I'd have a couple mounted to the truck for a vehicle launch system.
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Reply By: Niffty - Wednesday, May 02, 2007 at 22:15

Wednesday, May 02, 2007 at 22:15
If you sat on it you could be in the next dumd ass movie :-)
I rekon about 2 minutes of fame and a life time of pain!
Niffty
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AnswerID: 237548

Reply By: Member - Oldplodder (QLD) - Thursday, May 03, 2007 at 07:59

Thursday, May 03, 2007 at 07:59
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!
AnswerID: 237594

Follow Up By: Member No 1- Thursday, May 03, 2007 at 10:49

Thursday, May 03, 2007 at 10:49
I reckon can get the corks to hold at higher pressure ..but at what pressure does the pet bottles hold before rupturing?
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FollowupID: 498679

Follow Up By: Member - Oldplodder (QLD) - Thursday, May 03, 2007 at 20:41

Thursday, May 03, 2007 at 20:41
Only one way to find out. Test to destruction as the Myth Busters say.
You done it yet?
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FollowupID: 498810

Follow Up By: Member No 1- Friday, May 04, 2007 at 07:28

Friday, May 04, 2007 at 07:28
nope..not yet...but am going to give it a try on sunday
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Follow Up By: Middle Jeff - Friday, May 04, 2007 at 08:10

Friday, May 04, 2007 at 08:10
PET bottles will blow the lid off before they explode, I worked in a warehouse once and a forklift dropped a pallet of no name lemonade the things started to bounce everywhere great fun until the lids started to let go, one got me in the back and put on the floor with five little bruise marks on my back, sore and sticky!

Have fun

Craig
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Reply By: Robin - Thursday, May 03, 2007 at 08:05

Thursday, May 03, 2007 at 08:05
I'm more into nitrous oxide versions , but brother had home made one at Xmas camp. Using 1.5m Electrical conduit main tube and pumped to 100psi with arb compressor and about 900ml water.

It sure went straight up but only about 20m.

Robin Miller
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AnswerID: 237596

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