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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

Gardena Launcher+Floor Pump: How Best to Connect Them?

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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martan74
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Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by martan74 » Mon Mar 29, 2010 1:44 pm

Hi everyone,

Just joined and am in the process of sourcing parts for my first rocket and launcher. At the moment I'm planning to make a gardena type launcher like the one on Air Command's website, complete with the launch abort valve made from gardena connectors.

Initially the compression will come from a floor pump which presumably will have a Schrader valve connector. I'm just wondering if anyone can offer suggestions on the best way to connect the pump to the launcher? Is there an ideal type of hose to connect to the abort valve, to which I'll then have to attach a Schrader valve (I guess) so I can connect to the pump.

If anyone can advise what parts/techniques would be best, or if there's a better way altogether of doing it, it'd be greatly appreciated!

All the best,

Mark :?



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rockets-in-brighton
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Re: Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by rockets-in-brighton » Mon Mar 29, 2010 2:11 pm

I can't comment on the best way to make the emergency relief valve. For the main connection I use a valve stem of the sort you can get for about 50p each from car tyre shops (think Qwikfit or the like). These are compatible with track pump heads. You need to drill a hole into your launcher's pipework stop-end and force the valve stem into it from the inside, then fit it to your pipework. Note that this doesn't give you a non-return valve, I elevate the hose to achieve that.


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Steve
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rockets-in-brighton
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Re: Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by rockets-in-brighton » Mon Mar 29, 2010 2:12 pm

martan74 wrote:Hi everyone,

Just joined and am in the process of sourcing parts for my first rocket and launcher. At the moment I'm planning to make a gardena type launcher like the one on Air Command's website, complete with the launch abort valve made from gardena connectors.

Initially the compression will come from a floor pump which presumably will have a Schrader valve connector. I'm just wondering if anyone can offer suggestions on the best way to connect the pump to the launcher? Is there an ideal type of hose to connect to the abort valve, to which I'll then have to attach a Schrader valve (I guess) so I can connect to the pump.

If anyone can advise what parts/techniques would be best, or if there's a better way altogether of doing it, it'd be greatly appreciated!

All the best,

Mark :?


Cheers
Steve
Rockets-in-Brighton
WEB: http://groups.google.co.uk/group/rockets-in-brighton

Stevo14
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Re: Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by Stevo14 » Tue Mar 30, 2010 3:29 am

I would suggest using the smallest diameter hose possible to connect the pump to the launcher. If the launcher has too much internal volume, you are wasting energy pressurizing air that won't make your rocket go any higher. I use a 1.5 mm internal diameter hose to connect the pump and launcher, which makes it much easier to reach moderate pressures inside the rocket. To connect the 1.5 mm hose to the regular gardena size hose, I used a plastic hose adapter and "built out" from the smaller hose using other pieces of hose, a hose clamp and finally epoxy.



SaskAlex
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Re: Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by SaskAlex » Tue Mar 30, 2010 10:12 am

I use a pretty small hose too, but 1.5 mm is tiny. How long is your hose, Stevo? Any idea how much pressure is dropping across it? You waste energy filling a large hose, but you can also waste energy pumping air through a long skinny hose. Just try pumping air through it to the atmosphere and see how much work it is.



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WRA2
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Re: Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by WRA2 » Tue Mar 30, 2010 3:29 pm

martan74 wrote:Hi everyone,

Just joined and am in the process of sourcing parts for my first rocket and launcher. At the moment I'm planning to make a gardena type launcher like the one on Air Command's website, complete with the launch abort valve made from gardena connectors.

Initially the compression will come from a floor pump which presumably will have a Schrader valve connector. I'm just wondering if anyone can offer suggestions on the best way to connect the pump to the launcher? Is there an ideal type of hose to connect to the abort valve, to which I'll then have to attach a Schrader valve (I guess) so I can connect to the pump.

If anyone can advise what parts/techniques would be best, or if there's a better way altogether of doing it, it'd be greatly appreciated!

All the best,

Mark :?
Your best bet for making a safety pressure relief valve is to add a tee to your line near the pump and put a valve on it. It is the simplest to build and can be controlled near the pump. Ball valves work the best as they can be fully opened quickly (usually 1/4 to 1/2 tun from fully closed to fully open). Use whatever materials are available locally but make sure that all components are rated for more then the planned launch pressure.Overkill on pressure ratings is a good thing so get components that are rated as high as possible. You never know when you might get the urge to increase pressure so if your plumbing is rated for high pressures you will be ready. Search for pressure washer hoses valves and fittings.

Welcome to the world's largest water rocket community. :W


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Stevo14
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Re: Gardena Launcher+Floor Pump: How Best to Connect Them?

Post by Stevo14 » Wed Mar 31, 2010 2:07 am

SaskAlex wrote:I use a pretty small hose too, but 1.5 mm is tiny. How long is your hose, Stevo? Any idea how much pressure is dropping across it? You waste energy filling a large hose, but you can also waste energy pumping air through a long skinny hose. Just try pumping air through it to the atmosphere and see how much work it is.

The hose I use is about 5 meters long. The reason that I choose 1.5 mm is because the opening in my my home-made 1-way valve is about 1.5 mm. Even if I used a larger hose, the choke point at the 1-way valve is still only 1.5 mm. Maybe I am wrong, but I think using a hose larger than the smallest opening in the valve would not help me much.

In the past, I used a standard diameter hose for the whole 5 meters (with the same 1.5 mm 1-way valve). After switching to the much smaller diameter hose, it feels like it takes the same effort to pump as before (maybe because the choke point is the same?) but that I reach moderate pressures more quickly.



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