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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.

Is there a theoretical maximum altitude for a water rocket?

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HawaiiRockets
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Is there a theoretical maximum altitude for a water rocket?

Post by HawaiiRockets » Wed Sep 11, 2013 3:03 am

I'm wondering if anyone has done the math yet and if so what the results are? I realize the answer will vary depending upon the configuration, multiple stages, PET bottles only or fiberglass type rockets, etc.

To use an analogy, every fixed wing aircraft has something called the service ceiling listed in the pilot operating handbook specific to that aircraft. This is the maximum altitude at which an aircraft can no longer climb at least 100 feet per minute.



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Re: Is there a theoretical maximum altitude for a water rock

Post by Spaceman Spiff » Sat Sep 14, 2013 9:54 am

HawaiiRockets wrote:I'm wondering if anyone has done the math yet and if so what the results are? I realize the answer will vary depending upon the configuration, multiple stages, PET bottles only or fiberglass type rockets, etc.

To use an analogy, every fixed wing aircraft has something called the service ceiling listed in the pilot operating handbook specific to that aircraft. This is the maximum altitude at which an aircraft can no longer climb at least 100 feet per minute.
My guess would be that there is a mathematic absolute maximum for any given volume of water rocket, but if you wanted to say there is a fixed maximum altitude that could never be exceeded, then probably no. I think someone could just think up a theoretical water rocket that was 10 miles tall and simulate it leaving orbit.


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Re: Is there a theoretical maximum altitude for a water rock

Post by U.S. Water Rockets1 » Sat Sep 14, 2013 10:19 pm

Spaceman Spiff wrote:
HawaiiRockets wrote:I'm wondering if anyone has done the math yet and if so what the results are? I realize the answer will vary depending upon the configuration, multiple stages, PET bottles only or fiberglass type rockets, etc.

To use an analogy, every fixed wing aircraft has something called the service ceiling listed in the pilot operating handbook specific to that aircraft. This is the maximum altitude at which an aircraft can no longer climb at least 100 feet per minute.
My guess would be that there is a mathematic absolute maximum for any given volume of water rocket, but if you wanted to say there is a fixed maximum altitude that could never be exceeded, then probably no. I think someone could just think up a theoretical water rocket that was 10 miles tall and simulate it leaving orbit.
LOL. You may find that there isn't enough material on the Earth to make a 10 mile tall PET bottle! And since the experiment is based on Earth (altitude implies a launch from the Earth), you are stuck with what materials you can find here.


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Re: Is there a theoretical maximum altitude for a water rock

Post by arjan » Sun Sep 15, 2013 2:42 am

U.S. Water Rockets1 wrote:
Spaceman Spiff wrote:
HawaiiRockets wrote:I'm wondering if anyone has done the math yet and if so what the results are? I realize the answer will vary depending upon the configuration, multiple stages, PET bottles only or fiberglass type rockets, etc.

To use an analogy, every fixed wing aircraft has something called the service ceiling listed in the pilot operating handbook specific to that aircraft. This is the maximum altitude at which an aircraft can no longer climb at least 100 feet per minute.
My guess would be that there is a mathematic absolute maximum for any given volume of water rocket, but if you wanted to say there is a fixed maximum altitude that could never be exceeded, then probably no. I think someone could just think up a theoretical water rocket that was 10 miles tall and simulate it leaving orbit.
LOL. You may find that there isn't enough material on the Earth to make a 10 mile tall PET bottle! And since the experiment is based on Earth (altitude implies a launch from the Earth), you are stuck with what materials you can find here.
haha. That would require roughly 55495 2Liter bottles stacked on top of each other giving a total volume of 115984.55 Liters and a weight of 3329700 grams!
Clifford heath's simulators says: Now you're talkin' crazy talk! A volume of 1.15985e+08 is outside the range 0.001 to 1e+06

LOL


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Re: Is there a theoretical maximum altitude for a water rock

Post by HawaiiRockets » Sun Sep 15, 2013 8:23 am

I wanna put something in orbit



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Re: Is there a theoretical maximum altitude for a water rock

Post by bugwubber » Sun Sep 15, 2013 10:32 am

HawaiiRockets wrote:I wanna put something in orbit
Sure just a trip to the hardware store and you'll be set!

[youtube][/youtube]

I think for water rockets, your limiting factor is going to be your compressor and weight of the material used on your pressure vessel. Where do you get 10k psi AND safely contain it in a vessel that's light enough to fly?


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Re: Is there a theoretical maximum altitude for a water rock

Post by Spaceman Spiff » Sun Sep 15, 2013 11:18 am

Wasn't there some guy a while ago claiming that he was building a water rocket that would go 30,000 feet. LOL!


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Re: Is there a theoretical maximum altitude for a water rock

Post by HawaiiRockets » Sun Sep 15, 2013 2:13 pm

bugwubber wrote:
HawaiiRockets wrote:I wanna put something in orbit
Sure just a trip to the hardware store and you'll be set!

[youtube][/youtube]

I think for water rockets, your limiting factor is going to be your compressor and weight of the material used on your pressure vessel. Where do you get 10k psi AND safely contain it in a vessel that's light enough to fly?
Yeah I saw that show .... I think they estimated 50K feet ... Another guy in YouTube did 120'K feet.. but how high till u can orbit?



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Re: Is there a theoretical maximum altitude for a water rock

Post by bugwubber » Mon Sep 16, 2013 12:40 am

HawaiiRockets wrote:
bugwubber wrote:
HawaiiRockets wrote:I wanna put something in orbit
Sure just a trip to the hardware store and you'll be set!

[youtube][/youtube]

I think for water rockets, your limiting factor is going to be your compressor and weight of the material used on your pressure vessel. Where do you get 10k psi AND safely contain it in a vessel that's light enough to fly?
Yeah I saw that show .... I think they estimated 50K feet ... Another guy in YouTube did 120'K feet.. but how high till u can orbit?

Orbit is more about how fast. And the answer is around 17,000mph. You really have to be above the atmosphere to make those kinds of speeds possible- otherwise you end up just like all the meteors you see in the sky, heating up until you vaporize. Orbit is essentially falling but always missing the planet because of the sideways velocity.

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Re: Is there a theoretical maximum altitude for a water rock

Post by HawaiiRockets » Mon Sep 16, 2013 3:36 am

Good info bugwuber



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Re: Is there a theoretical maximum altitude for a water rock

Post by Spaceman Spiff » Tue Sep 17, 2013 5:16 pm

bugwubber wrote: Orbit is more about how fast. And the answer is around 17,000mph. You really have to be above the atmosphere to make those kinds of speeds possible- otherwise you end up just like all the meteors you see in the sky, heating up until you vaporize. Orbit is essentially falling but always missing the planet because of the sideways velocity.
Bugwubber
What if you didn't want to go into orbit? Say you decided to just lift off and fly straight up and just leave the Earth and fly out of the solar system. I don't think you need to go that fast at all.


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Re: Is there a theoretical maximum altitude for a water rock

Post by bugwubber » Tue Sep 17, 2013 10:04 pm

Spaceman Spiff wrote:
bugwubber wrote: Orbit is more about how fast. And the answer is around 17,000mph. You really have to be above the atmosphere to make those kinds of speeds possible- otherwise you end up just like all the meteors you see in the sky, heating up until you vaporize. Orbit is essentially falling but always missing the planet because of the sideways velocity.
Bugwubber
What if you didn't want to go into orbit? Say you decided to just lift off and fly straight up and just leave the Earth and fly out of the solar system. I don't think you need to go that fast at all.
Well as long as you had suffcient power and fuel, no. But NASA sent New Horizons on a direct route out of the Solar system (with gravity assists) and felt it needed to travel at over 37k mph to escape the Sun. I suppose they figured out it was more efficient to do it that way.

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Re: Is there a theoretical maximum altitude for a water rocket?

Post by Alien Space Agency » Mon Jan 11, 2016 6:08 pm

George once said a maximum of 5km.... Probably a carbon fiber/fiberglass rocket filled to 1111000 psi.... AAAAANNNNDDD a volume of 30L.


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Re: Is there a theoretical maximum altitude for a water rock

Post by motorcyclepilot » Tue Jan 12, 2016 11:24 pm

bugwubber wrote:
HawaiiRockets wrote:
bugwubber wrote:
Orbit is essentially falling but always missing the planet because of the sideways velocity.

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