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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.

A fully operational Water Rocket Derby Launching System

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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bugwubber
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A fully operational Water Rocket Derby Launching System

Post by bugwubber » Mon Mar 25, 2013 12:10 am

The Water Rocket Derby Launcher is now complete!
DSC09543.jpg
Design features-
1. Simultaneous rocket launcher. Can launch 1 or up to 5 rockets at the same time.
2. On launcher water fill. To make loading the water faster and easier.
3. Special purpose port. Launch tube 1 is removable and can be replaced with a specially configured launch tube such as ultra short, stepped, or for an alternate release mechanism.
4. Portability. LOL ok this is a large system. But it comes apart for transport and storage. The launch rail simply slides into the cross braces with no need for fasteners.
5. Stability. At over 3 feet wide, and very low COG, it won't tip over. Holes on the ends of the cross braces allow for stakes to prevent movement.
6. Dual mode. The launch rail can be installed on the horizontal mode cross braces to launch cars or rocket powered skis.
7. Simplicity. No special nozzles needed for rockets. Works with most bottle shapes and sizes. If it is a carbonated soft drink bottle, it will most likely fit.
8. Educational. Rocketeers will be able to immediately compare the effects of different fin sizes, bottle sizes and water levels.
DSC09545.jpg
DSC09546.jpg
DSC09549.jpg
Thanks,

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Re: A fully operational Water Rocket Derby Launching System

Post by Blenderite » Mon Mar 25, 2013 1:55 pm

Nice design.


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Re: A fully operational Water Rocket Derby Launching System

Post by ptx » Mon Mar 25, 2013 9:07 pm

Very nice! Did you test it?
Hope the water does not freeze ..


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Re: A fully operational Water Rocket Derby Launching System

Post by bugwubber » Mon Mar 25, 2013 10:46 pm

nunopt wrote:Very nice! Did you test it?
Hope the water does not freeze ..
When I launched Something Wicked, I had just a tiny bit of ice form on the launch tubes right around the o-rings. I have not done a vertical launch with water yet- just air only. Still missing one of those bottles by the way...


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Re: A fully operational Water Rocket Derby Launching System

Post by WRA2 » Mon Mar 25, 2013 10:57 pm

bugwubber wrote:
nunopt wrote:Very nice! Did you test it?
Hope the water does not freeze ..
When I launched Something Wicked, I had just a tiny bit of ice form on the launch tubes right around the o-rings. I have not done a vertical launch with water yet- just air only. Still missing one of those bottles by the way...
A good way to keep your water from freezing is to mix "blue stuff" (windshield cleaner/de-icer) with your water. The stuff is cheap and plentiful in cold climate areas.


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Re: A fully operational Water Rocket Derby Launching System

Post by bugwubber » Mon Mar 25, 2013 11:15 pm

WRA2 wrote:
bugwubber wrote:
nunopt wrote:Very nice! Did you test it?
Hope the water does not freeze ..
When I launched Something Wicked, I had just a tiny bit of ice form on the launch tubes right around the o-rings. I have not done a vertical launch with water yet- just air only. Still missing one of those bottles by the way...
A good way to keep your water from freezing is to mix "blue stuff" (windshield cleaner/de-icer) with your water. The stuff is cheap and plentiful in cold climate areas.
I'll keep that in mind. The pink RV antifreeze is nontoxic; although more expensive.


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Post by PTrockets » Wed Mar 27, 2013 7:34 pm

Very well done!
A little advice: When you launch lot of water rockets at the same time, they must have good aerodynamics (fins, nosecone, right weight, ...). This way, each rocket will fly straight and there is almost no risk of colliding with other rockets during the flight.

PTrockets



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Re: A fully operational Water Rocket Derby Launching System

Post by U.S. Water Rockets » Wed Mar 27, 2013 8:12 pm

What are the large boxed sections on each side made from? It looks to be made from PVC Fence Posts, but yours look stronger and thicker, so maybe this is a bad guess. The stripes you added to the finished product really make it look imposing. Good work!



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Re: A fully operational Water Rocket Derby Launching System

Post by bugwubber » Wed Mar 27, 2013 10:34 pm

Thanks y'all!

PTrockets- or in the case of my test launch, unguided bottles heading to all corners of the sky! I'll let you know when I find that last missing bottle. :-)

USWR- you are correct, 4 3/4" PVC fence posts. Lowes occasionally puts them on sale for a couple bucks each.
A little bit of your work is in there too. The o-rings on the launch tubes were installed based on that launcher guide published on your site.


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Re: A fully operational Water Rocket Derby Launching System

Post by U.S. Water Rockets » Thu Mar 28, 2013 4:47 pm

bugwubber wrote:Thanks y'all!

PTrockets- or in the case of my test launch, unguided bottles heading to all corners of the sky! I'll let you know when I find that last missing bottle. :-)

USWR- you are correct, 4 3/4" PVC fence posts. Lowes occasionally puts them on sale for a couple bucks each.
A little bit of your work is in there too. The o-rings on the launch tubes were installed based on that launcher guide published on your site.
Cool! We will have to keep an eye out for the sale on those posts because they look extremely useful!

Glad you were able to make use of our o-ring design. We've done a standalone tutorial on how to make the launch tube, separate from the launcher tutorial, so it's good to know that people would want to build just that part. We will have to put it online.



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Re: A fully operational Water Rocket Derby Launching System

Post by bugwubber » Fri Mar 29, 2013 1:03 pm

U.S. Water Rockets wrote:
bugwubber wrote:Thanks y'all!

PTrockets- or in the case of my test launch, unguided bottles heading to all corners of the sky! I'll let you know when I find that last missing bottle. :-)

USWR- you are correct, 4 3/4" PVC fence posts. Lowes occasionally puts them on sale for a couple bucks each.
A little bit of your work is in there too. The o-rings on the launch tubes were installed based on that launcher guide published on your site.
Cool! We will have to keep an eye out for the sale on those posts because they look extremely useful!

Glad you were able to make use of our o-ring design. We've done a standalone tutorial on how to make the launch tube, separate from the launcher tutorial, so it's good to know that people would want to build just that part. We will have to put it online.
The one thing I didn't do was glue the top piece of 1/2" pvc with the o-ring in place. Instead I cut a 1/8" spacer out of pvc, broke it in half, and then held it in place of the o-ring while I installed the pvc over the cpvc. Didn't know if the glue would mess up the o-ring or bond it, so played it safe.

Thanks,

Bugwubber


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Re: A fully operational Water Rocket Derby Launching System

Post by bugwubber » Fri Mar 29, 2013 10:49 pm

Ran my first vertical launch tests today with water from the water tower.

With low water pressure, the water automatically fills to whatever percent of atmospheric pressure the water psi is at.
I laughed at myself over not predicting that. Luckily I built the water tower on a variable height platform!

With water, minimum air PSI setting needs to be 60. Lower than that, the bottles move too slowly. For empty bottles the min PSI was 40. Which brings up the next observation- bottles with more water, take longer to launch. It is plainly evident in the video which bottles had more water in them.

Slow motion launch:
[youtube][/youtube]

Regular speed launch
[youtube][/youtube]


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Re: A fully operational Water Rocket Derby Launching System

Post by U.S. Water Rockets1 » Sat Mar 30, 2013 10:41 pm

Your observation about the amount of water impacting the launch speed is very interesting. We've never seen an experiment that proved it conclusively until now. That's very interesting. Is there a way to repeat the test with the same water volume in identical bottles only with weights added to the top (used water filled bottles). The repeat test would show if it is the weight of the water that slows down the launches, or if you are seeing an effect of the smaller air volume depleting the energy because it expands in a shorter time.


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Re: A fully operational Water Rocket Derby Launching System

Post by ptx » Sun Mar 31, 2013 3:06 pm

Interesting, I am thinking if the bottles at the left farther from the tank got an higher air pressure inside during water filling because of more air trapped inside the line, and so got less water (??)

Btw, I found here a bottle and maybe is the one u r missing. It crossed the atlantic :D


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Re: A fully operational Water Rocket Derby Launching System

Post by bugwubber » Sun Mar 31, 2013 11:21 pm

nunopt wrote:Interesting, I am thinking if the bottles at the left farther from the tank got an higher air pressure inside during water filling because of more air trapped inside the line, and so got less water (??)

Btw, I found here a bottle and maybe is the one u r missing. It crossed the atlantic :D
So that's where it went! Hey WRA we do we get some kinda medal for that? ;-)

Regarding the video, for that particular launch, I squeezed some of the bottles before loading to manipulate the water levels. However, yes, when I did the first water load, the launcher was tilted a bit to the right so the water went to the lower ones first, and more air from the pipe was pushed into the high end so less water loaded. If I fill the pipes with water prior to loading, I can minimize that effect.


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