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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.

Use of Bottled air

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Re: Use of Bottled air

Post by sporter2k5 » Tue Jun 03, 2008 2:57 pm

I think it goes unsaid that there should be nothing illegal done in the course of getting a record said. Perhaps it should be added to the rules just to be on the safe side. It would be simple to enforce because laws are cut and dried and easy to reference.

It would be hard to enforce a morality rule because this is subjective. There's no real definition of morality. Do you mean moral in a way that is meant to punish people for not being honest when they submit a record? If you just mean records will be discarded if you don't provide accurate data or fake data, then that is probably just a good thing to mention. Is that what you were getting at?


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Re: Use of Bottled air

Post by Team Seneca » Wed Jun 04, 2008 8:40 am

Steve,

I think if you can create your rule that makes 100% sure that people are using AIR and AIR ONLY, then that's getting closer to something I would be comfortable with. I still think you need to come up with a way to level off the other advantages and possible cheats that bottled air can give. You're forgetting that we still have to rule out the "stomp rocket" problem, and others as well.

Plus, I wasn't thinking about preventing people from entering bogus data when I proposed the "morality" rule. I just wanted to make up something to protect our hard work from plagiarism. I would like to share more details about my designs but have concerns that some kopykatz lurker will clone everything I've done and then use it for their own self aggrandization. I just want a clause that says you can't just clone what others have shared. I think if wording like this would encourage people to give more details of their designs without fear of having their generosity used against them.

On the other hand, your interpretation of my suggestion is broader and covers my concerns as well as others I didn't think of. I think you should go forward with your suggestion.

If you can solve these issues and propose changes then I would think if we have a vote that it would be unanimous.


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Re: Use of Bottled air

Post by Tim Chen » Wed Jun 04, 2008 10:19 am

Here's an idea:

If we want to prevent someone from making a stomp rocket, what if the rules were to specify that if you use a tank for your air supply then you have to use a small nozzle diameter? That would prevent them from getting a large piston action.


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Re: Use of Bottled air

Post by Spaceman Spiff » Wed Jun 04, 2008 12:29 pm

Tim Chen wrote:Here's an idea:

If we want to prevent someone from making a stomp rocket, what if the rules were to specify that if you use a tank for your air supply then you have to use a small nozzle diameter? That would prevent them from getting a large piston action.


I think people would complain if you limited the nozzle size. What if you limit the length of the launch tube to prevent people from doing stomp rocket launches?


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Re: Use of Bottled air

Post by sporter2k5 » Wed Jun 04, 2008 8:36 pm

Team Seneca wrote:Steve,

I think if you can create your rule that makes 100% sure that people are using AIR and AIR ONLY, then that's getting closer to something I would be comfortable with. I still think you need to come up with a way to level off the other advantages and possible cheats that bottled air can give. You're forgetting that we still have to rule out the "stomp rocket" problem, and others as well.

Plus, I wasn't thinking about preventing people from entering bogus data when I proposed the "morality" rule. I just wanted to make up something to protect our hard work from plagiarism. I would like to share more details about my designs but have concerns that some kopykatz lurker will clone everything I've done and then use it for their own self aggrandization. I just want a clause that says you can't just clone what others have shared. I think if wording like this would encourage people to give more details of their designs without fear of having their generosity used against them.

On the other hand, your interpretation of my suggestion is broader and covers my concerns as well as others I didn't think of. I think you should go forward with your suggestion.

If you can solve these issues and propose changes then I would think if we have a vote that it would be unanimous.


Please don't use this topic to play "Tit for tat" with other folks. If you want to contribute to the discussion then great. Just take your disagreements to email. I don't care who's doing what to you if it's off topic.

In addition to "stomp rockets" what else is concerning you?


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Re: Use of Bottled air

Post by Tim Chen » Wed Jun 04, 2008 10:30 pm

Spaceman Spiff wrote:
Tim Chen wrote:Here's an idea:

If we want to prevent someone from making a stomp rocket, what if the rules were to specify that if you use a tank for your air supply then you have to use a small nozzle diameter? That would prevent them from getting a large piston action.


I think people would complain if you limited the nozzle size. What if you limit the length of the launch tube to prevent people from doing stomp rocket launches?


Good idea! I could live with that. It seems like a good compromise. I wonder how anyone could object.


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Re: Use of Bottled air

Post by Tim Chen » Wed Jun 04, 2008 10:47 pm

sporter2k5 wrote:In addition to "stomp rockets" what else is concerning you?


It doesn't seem fair that people who are "certified" or whatever you have to do to own and operate SCUBA tanks get to have shorter fill times over someone who can't easily get trained or certified or whatever. It might take them 30 seconds to fill up their rocket with a tank and it might take my team 10 minutes with a compressor. That's 9:30 of extra time they get to use in the 2 hour window for consecutive flights. There aren't exactly SCUBA shops on every street corner here in NH, and I wouldn't know where to begin looking for a school or even what the fees are, so I don't have any choice but to use compressors. I get the feeling this is the most cost effective way. I just don't want a bunch of surfer dudes from Hawai'i to get extra time because they have easy access to the equipment and training based on where they live. It's very likely they already SCUBA dive so they already have what they need or at least they can justify buying the equipment because they can enjoy that hobby as well. It's already bad enough they get launch weather year round!


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Re: Use of Bottled air

Post by The Mooseheads » Thu Jun 05, 2008 9:57 am

I like the brainstorming I see going on here. Keep up the good work you guys. I think you're onto something. If you can make it fair then I don't see any problems adopting a change to the rules.


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Re: Use of Bottled air

Post by The Mooseheads » Thu Jun 05, 2008 10:00 am

Tim Chen wrote:
sporter2k5 wrote:In addition to "stomp rockets" what else is concerning you?


It doesn't seem fair that people who are "certified" or whatever you have to do to own and operate SCUBA tanks get to have shorter fill times over someone who can't easily get trained or certified or whatever. It might take them 30 seconds to fill up their rocket with a tank and it might take my team 10 minutes with a compressor. That's 9:30 of extra time they get to use in the 2 hour window for consecutive flights. There aren't exactly SCUBA shops on every street corner here in NH, and I wouldn't know where to begin looking for a school or even what the fees are, so I don't have any choice but to use compressors. I get the feeling this is the most cost effective way. I just don't want a bunch of surfer dudes from Hawai'i to get extra time because they have easy access to the equipment and training based on where they live. It's very likely they already SCUBA dive so they already have what they need or at least they can justify buying the equipment because they can enjoy that hobby as well. It's already bad enough they get launch weather year round!


Tim, Too bad there's no good advantages for water rockets that can be had from owning snowmobiles or skis! We'd be sitting pretty! :twisted:


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Re: Use of Bottled air

Post by Spaceman Spiff » Thu Jun 05, 2008 1:36 pm

Tim Chen wrote:It might take them 30 seconds to fill up their rocket with a tank and it might take my team 10 minutes with a compressor. That's 9:30 of extra time they get to use in the 2 hour window for consecutive flights.


Another strike against tanks is that if you can fill your rocket in 30 seconds then you can do that chemical deploy trick with vinegar and baking soda to make the reaction more powerful. The reaction is almost instantaneous and very violent if you heat up the vinegar. If someone uses a compressor the vinegar will cool off while the rocket is filling, unless you add the hot chems after filling the rocket with pressure. You'd have to design a way to do that by remote control so you didn't get close to the rocket too.


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Re: Use of Bottled air

Post by The Mooseheads » Thu Jun 05, 2008 3:22 pm

Spaceman Spiff wrote:Another strike against tanks is that if you can fill your rocket in 30 seconds then you can do that chemical deploy trick with vinegar and baking soda to make the reaction more powerful. The reaction is almost instantaneous and very violent if you heat up the vinegar. If someone uses a compressor the vinegar will cool off while the rocket is filling, unless you add the hot chems after filling the rocket with pressure. You'd have to design a way to do that by remote control so you didn't get close to the rocket too.


Even if you had a way to remotely heat the solution or fill it by remote control then your rocket is sitting all that time while it is pressurizing with an UNARMED deploy. If it launches accidentally, it will have no deploy and will crash.


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Re: Use of Bottled air

Post by Mark Chen » Thu Jun 05, 2008 5:44 pm

:?: :?: :?: :?: :?:


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Re: Use of Bottled air

Post by Tim Chen » Fri Jun 06, 2008 8:45 am

Spaceman Spiff wrote:
Tim Chen wrote:It might take them 30 seconds to fill up their rocket with a tank and it might take my team 10 minutes with a compressor. That's 9:30 of extra time they get to use in the 2 hour window for consecutive flights.


Another strike against tanks is that if you can fill your rocket in 30 seconds then you can do that chemical deploy trick with vinegar and baking soda to make the reaction more powerful. The reaction is almost instantaneous and very violent if you heat up the vinegar. If someone uses a compressor the vinegar will cool off while the rocket is filling, unless you add the hot chems after filling the rocket with pressure. You'd have to design a way to do that by remote control so you didn't get close to the rocket too.


It would be a similar advantage when running your camera too. If it only has to run for 30 seconds you can use one of those all-in-one cameras that records for a minute or two. Just start it going, fill the rocket, and launch. If you have to wait for the fill a while then you have to get a more expensive camera that can record for a long time while filling up. You can also use those watch batteries to make your rocket lighter if the cameera only has to run for a few seconds while filling. Otherwise you have to come up with a way to operate the camera remotely, and that too adds weight.

Something I thought might also be unfair is that if you can fill up your rocket in only a few seconds that means you can wait for ideal conditions and fill up and launch right away. If you have to wait for the rocket to fill for 10 minutes then you have to hope that winds don't pick up or something when you're ready to launch. I would see this is a definite disadvantage too.

If these things can be made fair I don't have a problem. I just don't think you can make it fair for everyone easily and verifyably.


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Re: Use of Bottled air

Post by The Mooseheads » Fri Jun 06, 2008 10:34 am

I think a simple solution to even the playing field would be to stipulate that anybody using a tank must fill the rocket and then wait a predetermined time (based on pressure) before launching. They would show this in a raw unedited ground camera video as proof.

Would this be an acceptable solution?


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Re: Use of Bottled air

Post by Spaceman Spiff » Fri Jun 06, 2008 1:05 pm

The Mooseheads wrote:I think a simple solution to even the playing field would be to stipulate that anybody using a tank must fill the rocket and then wait a predetermined time (based on pressure) before launching. They would show this in a raw unedited ground camera video as proof.

Would this be an acceptable solution?


I'd go along with that. I'd love to see if anyone was really being put off by the compressor requirement. It's always been a hot topic.


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