A fully operational Water Rocket Derby Launching System

[bugwubber]

The Water Rocket Derby Launcher is now complete!

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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.

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Thanks,

Bugwubber
Team S.P.E.W.
Zimmerman, MN

[Blenderite]

Nice design.

[ptx]

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

[bugwubber]

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...

[WRA2]

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.

[bugwubber]

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.

[PTrockets]

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

[U.S. Water Rockets]

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!

[bugwubber]

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.

[U.S. Water Rockets]

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.

[bugwubber]

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

[bugwubber]

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]

[U.S. Water Rockets1]

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.

[ptx]

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

[bugwubber]

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

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.