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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.

Cheezy Water Rocket Toy with Potential

Discussions about rockets, construction materials, adhesives, nozzles, nosecones and fin design.
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Alien Space Agency
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Re: Cheezy Water Rocket Toy with Potential

Post by Alien Space Agency » Sat Mar 05, 2016 4:36 am

Oh, doesn't it put too much stress on the interstage?


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Re: Cheezy Water Rocket Toy with Potential

Post by Astrofox » Sun Mar 06, 2016 2:45 pm

So, will there be instructions on how to build such a staging mechanism on instructables? It seems to me like this is a very efficient and fairly easy way to have multi-stage rockets.



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Re: Cheezy Water Rocket Toy with Potential

Post by bugwubber » Thu Jun 30, 2016 1:09 am

Astrofox wrote:So, will there be instructions on how to build such a staging mechanism on instructables? It seems to me like this is a very efficient and fairly easy way to have multi-stage rockets.
One day! :-)


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China_WaterRocket
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Re: Cheezy Water Rocket Toy with Potential

Post by China_WaterRocket » Sat Feb 11, 2017 9:57 pm

I know how it works


I come from China, do not understand English, your information I use the translation software to view. I like water rockets, technology is the same, I hope we can become friends.

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Re: Cheezy Water Rocket Toy with Potential

Post by China_WaterRocket » Sat Feb 11, 2017 9:58 pm

But I don't know how to send pictures in the Forum


I come from China, do not understand English, your information I use the translation software to view. I like water rockets, technology is the same, I hope we can become friends.

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Re: Cheezy Water Rocket Toy with Potential

Post by Braaainz » Sun Jul 29, 2018 9:59 pm

So any videos of this stager with successful flight?



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Re: Cheezy Water Rocket Toy with Potential

Post by kitestring » Sun Jul 29, 2018 10:54 pm

Braaainz wrote:
Sun Jul 29, 2018 9:59 pm
So any videos of this stager with successful flight?
I did a trial in 2016.. I haven't an opportunity to do again since then.. Worked fine in principle.



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Re: Cheezy Water Rocket Toy with Potential

Post by Braaainz » Mon Jul 30, 2018 3:57 am

kitestring wrote:
Sun Jul 29, 2018 10:54 pm
Braaainz wrote:
Sun Jul 29, 2018 9:59 pm
So any videos of this stager with successful flight?
I did a trial in 2016.. I haven't an opportunity to do again since then.. Worked fine in principle.
Where do you think your leaks were coming from?



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Re: Cheezy Water Rocket Toy with Potential

Post by kitestring » Mon Jul 30, 2018 4:05 am

Braaainz wrote:
Mon Jul 30, 2018 3:57 am
kitestring wrote:
Sun Jul 29, 2018 10:54 pm
Braaainz wrote:
Sun Jul 29, 2018 9:59 pm
So any videos of this stager with successful flight?
I did a trial in 2016.. I haven't an opportunity to do again since then.. Worked fine in principle.
Where do you think your leaks were coming from?
From a launcher issue, not the rocket



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Re: Cheezy Water Rocket Toy with Potential

Post by sebswift » Tue Aug 28, 2018 11:43 am

I recently started experimenting with a similar concept like this thread. It is a fully 3d printed release mechanism with an internal non-return system (holds pressure in one direction but slowly bleeds it off if 2nd stage fires prematurely). Here is a test video. First step was to depressurize the first stage to test the non-return valve. Then I manually triggered the air-flap on my tommy-timer system. The timer releases a radial deploy sleeve (Thanks USWR!) which takes the pressure off of three claw-arms that hold the 2nd stage. A parachute would be tucked in there as well. The hinges on the claws are also 3D printed. The system just needs two o-rings, a washer, and a 1/4" rubber ball bearing. I printed a 3D section view of the mechanism which I can post if anyone wants to see how the non-return system work. I have not launched this yet.




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Re: Cheezy Water Rocket Toy with Potential

Post by sebswift » Tue Aug 28, 2018 12:00 pm

Here is a section rendering of the device (video in last post). The Non-return valve rubber ball bearing is dropped into the device during the printing and the system continues to print around the bearing. The hinge pins are also 3D printed. This version uses 3 claws to hold the second stage which allows just enough room for a first stage parachute.
multi-stage-section.png
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Re: Cheezy Water Rocket Toy with Potential

Post by Braaainz » Wed Aug 29, 2018 6:07 pm

I am eagerly awaiting to hear about the launch.

I think the time delay would make for a higher height than a crushing sleeve, thoughts?

Times like this, I wish I had a computer for simulator use. I only have a smartphone. Anyone know of a simulation that run on an Android phone?



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Re: Cheezy Water Rocket Toy with Potential

Post by bugwubber » Fri Aug 31, 2018 8:36 pm

Awesome!


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anachronist
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Re: Cheezy Water Rocket Toy with Potential

Post by anachronist » Sun Sep 02, 2018 11:05 am

Braaainz wrote:
Wed Aug 29, 2018 6:07 pm
I think the time delay would make for a higher height than a crushing sleeve, thoughts?
Answer is "it depends." Generally you get more altitude by increasing max velocity (as in, no delay), rather than by letting the rocket slow down before the second stage fires.

However, increasing velocity also increases drag (which goes up as the square of velocity), which might mean that the energy used to overcome that drag is wasted when it could have been used to accelerate the rocket from a slower speed by adding a delay. There may be an optimum delay time, greater than zero, but less than waiting for first stage apogee before firing the second stage. I don't know but I suspect the answer is closer to zero delay.

I can modify my simulator to test some scenarios.



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Re: Cheezy Water Rocket Toy with Potential

Post by anachronist » Sun Sep 02, 2018 12:25 pm

OK, I was wrong, it helps to have a small delay before firing the second stage. Here are some simulations. Arbitrarily, I set:
  • 2L bottle for each stage
  • each stage filled with 0.5L of water
  • no flow restriction on each stage, standard 22mm nozzle diameter
  • 200g of ballast (instruments, staging mechanism, fins, etc.), reducing to 100g when first stage falls away
  • 200 mm launch tube on first stage
  • drag coefficient of 0.2
Test 1: no delay - second stage fires when first stage runs out of water
Velocity and altitude on second stage firing: 24.4 m/s, 0.92 m
Final altitude: 134 m

Test 2: small delay - 0.5 sec delay from launch to fire second stage
Velocity and altitude on second stage firing: 23.2 m/s, 12 m
Final altitude: 143 m

Test 3: medium delay - 1 sec delay from launch to fire second stage
Velocity and altitude on second stage firing: 18 m/s, 22.3 m
Final altitude: 147 m

Test 4: large delay - 2 sec delay from launch (almost to apogee of 2-stage assembly with 2nd stage still full)
Velocity and altitude on second stage firing: 7.9 m/s, 35.3 m
Final altitude: 146 m

Conclusion: For the tested configuration, a small delay before firing the second stage achieves some additional altitude, by about 10% over firing the second stage immediately after the water is exhausted from the first stage. Optimal delay is about 1 second from launch. Any delay more than 2 seconds risks firing the second stage after reaching apogee from first stage.



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