New staging mechanism and Launcher

Water Rockets NSW

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air.command
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New staging mechanism and Launcher

Postby air.command » Tue Jan 22, 2008 12:57 pm

We have done a couple of updates in recent weeks to our website that describe a new staging mechanism that we have been working on for multi-stage water rockets:

http://www.AirCommandRockets.com/day51.htm

Image

Also more recently we have been building a new launcher for clustered water rockets. This new launcher is rated to 500psi (36 bar). The following update describes some of the design.

http://www.AirCommandRockets.com/day52.htm

I don't think we will have the launcher and rocket finished in time for this weekend's NSWRA meet (we'll bring our other rockets), but should be ready for the next one. The above update also includes tests of a booster segment that will be launched from the new launcher.

Image


Calculations show the main stage should go above 600 feet, but likely to around 700 feet at higher pressure (130psi). The main stage will use a 7mm nozzle and use foam for thrust. This combination gives around 7 seconds of thrust.

Here is a video of what that looks like on a static test stand. (The rocket capacity will be the same as in this test) The 7 second burn is the last one in the video.

http://www.AirCommandRockets.com/day31.htm#vid_thrustmeasurement

- George
Crop Circles: ... just a bunch of guys looking for their rockets ....

Kryten
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Postby Kryten » Tue Jan 22, 2008 3:51 pm

You've certainly been busy since you've returned home!
Amazing stuff!
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astroboy
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Postby astroboy » Tue Jan 22, 2008 7:32 pm

Thats some cool stuff there air.command. I know exactly what it is like to step through video frame by frame to get your performance curves. But you are lucky its just 60/sec!
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air.command
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Postby air.command » Wed Jan 23, 2008 8:38 pm

astroboy wrote:I know exactly what it is like to step through video frame by frame to get your performance curves.


hee hee ... that was a few nights of typing lots of numbers. I don't want to do that again any time soon. :? Definitely automated logging is necessary.
Crop Circles: ... just a bunch of guys looking for their rockets ....

Riddles81
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Gardena Quick Release Hose Connector

Postby Riddles81 » Tue Feb 26, 2008 7:11 pm

I have been looking at the Gardena hose connectors and I'm having a little trouble understanding how it can be used.

Correct me if I'm wrong but doesn't the hose connector allow the water held in the rocket to run back into the length of hose that is used to pressurised to rocket? So say you have a 10m hose between the air pump valve and the rocket then surely the amount of water in the rocket would completely drain into the hose leaving nothing in the rocket at all?

Can anyone who used this kind of launcher give me an idea of how this can possibly work?

Cheers
Riddles

air.command
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Postby air.command » Tue Feb 26, 2008 7:35 pm

Hi Riddles,

You are correct, that is exactly what can happen, and so most people use a non-return valve in the air hose close to the Gardena mechanism. These are typically made from bicycle tyre valves. These valves make it also easy to connect your air supply hose from a bicycle pump or a foot pump.

The alternative is to make the air hose go up like an S-bend above the water line in the rocket. This will also mostly keep the water in the rocket without draining into all of the hose.
Crop Circles: ... just a bunch of guys looking for their rockets ....

Riddles81
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Gardena Hose

Postby Riddles81 » Wed Feb 27, 2008 11:25 am

Thanks air.command,

From the designs I've seen I will definitely need at least one valve to allow me to pump up the bottle, various websites recommend putting the valve on the end of the long line so there's no wasted effort when you are pumping (i.e. keep the air lines pressurised as well as the bottle). Obviously doing it this way will mean the water can travel up the hose as in my previous message.

Would you recommend putting two valve's in (one at the end of the air line, one right up close to the Gardena connector? Or is it easier/better to put just one valve up near the connector to stop the water draining out and simply deal with the wasted effort of loosing air pressure in the hose after each pump?

Cheers
Riddles


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