Launch tube question

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
nonickname
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Launch tube question

Post by nonickname »

Well I'm designing a new, advanced launcher and I have two materials available for a launch tube.

The first is traditional 'ol pvc, with a very tight fit in the bottle neck.

Second, I have some aluminum tube which is close, but around 1mm off ideal perhaps.

The question being, I want aesthetics AND more safety at higher pressures (FTC with braid rockets) so is it ok to use the aluminum tube? What kind of performance losses would I be looking at with the 1mm or so of blowby?

Thanks
Aquafire
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Re: Launch tube question

Post by Aquafire »

nonickname wrote:Well I'm designing a new, advanced launcher and I have two materials available for a launch tube.

The first is traditional 'ol pvc, with a very tight fit in the bottle neck.

Second, I have some aluminum tube which is close, but around 1mm off ideal perhaps.

The question being, I want aesthetics AND more safety at higher pressures (FTC with braid rockets) so is it ok to use the aluminum tube? What kind of performance losses would I be looking at with the 1mm or so of blowby?

Thanks
I think the PVC tube in that diameter is not rated more than 500PSI, so if you make a launch tube from that pipe then it could explode at the exit of the nozzle. If aluminum is rater for higher pressure then it would be safer.
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U.S. Water Rockets1
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Re: Launch tube question

Post by U.S. Water Rockets1 »

You might want to consider building external guide rails for your rocket to keep it aligned on the pad. Using a launch tube seems to be confusing to some people. There's a forum in Germany where most of the members assume that water rockets with launch tubes don't use water reaction mass for propulsion.

Does this forum have a translation feature? We could talk about it in detail and try and get them to join up and discuss. It could raise awareness in Europe for the WRA2 record competitions hosted here.
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nonickname
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Re: Launch tube question

Post by nonickname »

A translator like babelfish is easy enough to use.

I may just hold off with a new launcher until I get my mini-lathe (late july or after) and custom machine parts. I'm thinking a 12mm launch tube (nozzle would be 12mm/.477") with a double o-ring seal. Custom machined convergent diameter or de laval nozzle perhaps? Most likely a single hook or a hold down plate like the bigfoot rocket launcher. And 3 hardened steel external guide rods.
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rockets-in-brighton
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Re: Launch tube question

Post by rockets-in-brighton »

U.S. Water Rockets1 wrote:You might want to consider building external guide rails for your rocket to keep it aligned on the pad. Using a launch tube seems to be confusing to some people. There's a forum in Germany where most of the members assume that water rockets with launch tubes don't use water reaction mass for propulsion.

Does this forum have a translation feature? We could talk about it in detail and try and get them to join up and discuss. It could raise awareness in Europe for the WRA2 record competitions hosted here.
Assuming it's RaketenModellBau, which sub-forum has this discussion?
Cheers
Steve
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Batkiter
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Launch tube question

Post by Batkiter »

rockets-in-brighton wrote:
U.S. Water Rockets1 wrote:You might want to consider building external guide rails for your rocket to keep it aligned on the pad. Using a launch tube seems to be confusing to some people. There's a forum in Germany where most of the members assume that water rockets with launch tubes don't use water reaction mass for propulsion.

Does this forum have a translation feature? We could talk about it in detail and try and get them to join up and discuss. It could raise awareness in Europe for the WRA2 record competitions hosted here.
Assuming it's RaketenModellBau, which sub-forum has this discussion?

Here my advice for a launchtube-solution!

15mm copper-tube whit no-return-valve on the bottom. And the the special 15,05mm nozzle. Has minimum space between tube and nozzle inside diameter. Powerfull punch!

Greetings Batkiter
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U.S. Water Rockets1
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Re: Launch tube question

Post by U.S. Water Rockets1 »

nonickname wrote:A translator like babelfish is easy enough to use.

I may just hold off with a new launcher until I get my mini-lathe (late july or after) and custom machine parts. I'm thinking a 12mm launch tube (nozzle would be 12mm/.477") with a double o-ring seal. Custom machined convergent diameter or de laval nozzle perhaps? Most likely a single hook or a hold down plate like the bigfoot rocket launcher. And 3 hardened steel external guide rods.
The forum software does not work with the online translators. It blocks any links from working with the translator so when you try and click on any link to navigate to any other page then it gives an error. The only way to read anything is if you have a direct link to feed to the translator or the text from the page which you can paste into the translator.
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Re: Launch tube question

Post by U.S. Water Rockets1 »

rockets-in-brighton wrote:
U.S. Water Rockets1 wrote:You might want to consider building external guide rails for your rocket to keep it aligned on the pad. Using a launch tube seems to be confusing to some people. There's a forum in Germany where most of the members assume that water rockets with launch tubes don't use water reaction mass for propulsion.

Does this forum have a translation feature? We could talk about it in detail and try and get them to join up and discuss. It could raise awareness in Europe for the WRA2 record competitions hosted here.
Assuming it's RaketenModellBau, which sub-forum has this discussion?
That's the forum. The topic is down in the first category under "water rockets" (in German). It shouldn't be too hard to locate. It's called "German Record" (also in German).

It's a shame the translator does not work correctly because it's difficult to really follow the conversation. Correct us if we're wrong but as far as we can tell they have their own altitude competition and someone recently broke their record using a launch tube which caused the previous record holder to change the rules to forbid the use of a launch tube.

For some strange reason the translation as we interpret it says the guy in charge has made an exception to the rule to allow the new guy to keep the title even though his rocket uses a launch tube but they don't recognise any of our USWR flights because we use a launch tube. That doesn't make any sense.
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rockets-in-brighton
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Re: Launch tube question

Post by rockets-in-brighton »

U.S. Water Rockets1 wrote:
rockets-in-brighton wrote:
U.S. Water Rockets1 wrote:You might want to consider building external guide rails for your rocket to keep it aligned on the pad. Using a launch tube seems to be confusing to some people. There's a forum in Germany where most of the members assume that water rockets with launch tubes don't use water reaction mass for propulsion.

Does this forum have a translation feature? We could talk about it in detail and try and get them to join up and discuss. It could raise awareness in Europe for the WRA2 record competitions hosted here.
Assuming it's RaketenModellBau, which sub-forum has this discussion?
That's the forum. The topic is down in the first category under "water rockets" (in German). It shouldn't be too hard to locate. It's called "German Record" (also in German).

It's a shame the translator does not work correctly because it's difficult to really follow the conversation. Correct us if we're wrong but as far as we can tell they have their own altitude competition and someone recently broke their record using a launch tube which caused the previous record holder to change the rules to forbid the use of a launch tube.

For some strange reason the translation as we interpret it says the guy in charge has made an exception to the rule to allow the new guy to keep the title even though his rocket uses a launch tube but they don't recognise any of our USWR flights because we use a launch tube. That doesn't make any sense.

OK, I found the thread. Incidentally, Google Translate used to work perfectly with this forum until very recently, as I got the best results by using it and BabelFish side-by-side to get the best sense by combining the translations. BabelFish still works: http://babelfish.yahoo.com/translate_ur ... =Translate

Anyway, the gist of the conversation is that a small group of experienced water rocketeers are trying to agree a set of criteria under which to compete for best height; the purpose being mutual entertainment and promotion of the sport. The current "winner" used a launch tube and the previous record holder said that he had long felt that launch tubes were against the spirit of the competition - specifically that a long launch tube combined with a narrow rocket body and a wide nozzle result in a piston launch rather than a true rocket engine. On those grounds the USWR rocket would not be eligible. However, it looks to be more in the nature of a friendly contest among friends, hence the generous agreement that the new record holder should keep the record after thesuggested change to the rules.

Perhaps one of our native German speakers could confirm if I got that right?
Cheers
Steve
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Batkiter
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Re: Launch tube question

Post by Batkiter »

OK, I found the thread. Incidentally, Google Translate used to work perfectly with this forum until very recently, as I got the best results by using it and BabelFish side-by-side to get the best sense by combining the translations. BabelFish still works: http://babelfish.yahoo.com/translate_ur ... =Translate

Anyway, the gist of the conversation is that a small group of experienced water rocketeers are trying to agree a set of criteria under which to compete for best height; the purpose being mutual entertainment and promotion of the sport. The current "winner" used a launch tube and the previous record holder said that he had long felt that launch tubes were against the spirit of the competition - specifically that a long launch tube combined with a narrow rocket body and a wide nozzle result in a piston launch rather than a true rocket engine. On those grounds the USWR rocket would not be eligible. However, it looks to be more in the nature of a friendly contest among friends, hence the generous agreement that the new record holder should keep the record after thesuggested change to the rules.

Perhaps one of our native German speakers could confirm if I got that right?[/quote]

Hallo Steve!


With your estimate you lie perfectly correctly. We start and build our rockets exactly after this guideline. With this method we achieve a large resonance among the rocket builders and the fun are guaranteed.

Gruß Claus (Batkiter)
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Re: Launch tube question

Post by dongfang »

Hi,

If someone can post a link to the original German page, I can try translate (or just the passages that the autotranslator stumbles in). I know both German and English so-so.

Regards
Soren
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Re: Launch tube question

Post by Batkiter »

dongfang wrote:Hi,

If someone can post a link to the original German page, I can try translate (or just the passages that the autotranslator stumbles in). I know both German and English so-so.

Regards
Soren
Hi Soren!

The original website of german waterrocketeers is: http://www.raketenmodellbau.org

If you need help, translation or information about our forum, let me know.

Regards

Batkiter
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Re: Launch tube question

Post by WRA2 »

Batkiter wrote:
dongfang wrote:Hi,

If someone can post a link to the original German page, I can try translate (or just the passages that the autotranslator stumbles in). I know both German and English so-so.

Regards
Soren
Hi Soren!

The original website of german waterrocketeers is: http://www.raketenmodellbau.org

If you need help, translation or information about our forum, let me know.

Regards

Batkiter
Hello Batkiter,

How about posting the results of the competition to this forum? I'm sure all our members here would be interested. Just start a new topic in our "personal or team best" forum.

http://www.wra2.org/forum/viewforum.php?f=36

Just start a new thread with the name of the competition. If this gains popularity we could rename the "Personal best forum" to include other organized competitions. :D :D :D
Lisa Walker,
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:WRA2:The Water Rocket Achievement World Record Association :WRA2:
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Re: Launch tube question

Post by Tim Chen »

I would like to see the results too. You guys in Europe have the biggest gatherings of water rocketeers I've seen and the videos are always great! Keep us informed!
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Re: Launch tube question

Post by U.S. Water Rockets1 »

Batkiter wrote:
dongfang wrote:Hi,

If someone can post a link to the original German page, I can try translate (or just the passages that the autotranslator stumbles in). I know both German and English so-so.

Regards
Soren
Hi Soren!

The original website of german waterrocketeers is: http://www.raketenmodellbau.org

If you need help, translation or information about our forum, let me know.

Regards

Batkiter

There's a guy over there who appears to think that our water rockets do not use any water and that the launch tube is the source of thrust. It would be easy to feel this way if he cannot read the rules we followed because they are posted in English. If you run a simulator with a very high pressure pneumatic rocket that it won't accelerate well because the tube is so short. If you try the simulator with a water rocket at high pressure you will see it doesn't add a great deal of altitude. The sole purpose of our launch tube is to provide stability for our rocket while on the launch pad. We cannot launch at a 90 degree angle because we need to land away from trees so we have to launch the rocket angled away from the trees. Because we are not vertical the rocket must be held at the launch angle while pressurizing and so we use the launch tube to support the weight of the rocket using internal guides. Without the launchtube, there are large torque forces on the nozzle at the angle we launch with. The long heavy rocket we fly acts as a lever and can damage our launch mechanism if we do not support it with the launch tube.

Hopefully, someone can relay this back so that there's no misunderstanding.
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