Welcome to the Water Rocket Forum, sponsored by The Water Rocket Achievement World Record Association.

The largest, most sophisticated and ground breaking group supporting you, the serious water rocket flyer! Whether you are a beginner or an expert, the WRA2 has something for everyone.

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.

Launch tube question

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
nonickname
Advanced Member
Advanced Member
Posts: 15
Joined: Wed Nov 26, 2008 5:39 am

Launch tube question

Post by nonickname » Fri May 08, 2009 9:13 pm

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
Advanced Member
Advanced Member
Posts: 43
Joined: Wed Dec 26, 2007 5:58 pm

Re: Launch tube question

Post by Aquafire » Sat May 09, 2009 3:30 pm

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.



User avatar
U.S. Water Rockets1
WRA2 Member
WRA2 Member
Posts: 1771
Joined: Sat Feb 03, 2007 3:24 pm

Re: Launch tube question

Post by U.S. Water Rockets1 » Sat May 09, 2009 9:54 pm

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.


Team U.S. Water Rockets
Visit USWaterRockets.com
Visit our Blog
Tune in to our YouTube Channel
Visit our Facebook page
Visit our Twitter Page
Opportunity is missed by most people because it is dressed in overalls and looks like work. --Thomas Edison

nonickname
Advanced Member
Advanced Member
Posts: 15
Joined: Wed Nov 26, 2008 5:39 am

Re: Launch tube question

Post by nonickname » Sun May 10, 2009 12:12 am

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.



User avatar
rockets-in-brighton
Senior Member
Senior Member
Posts: 431
Joined: Fri Jun 20, 2008 12:33 pm

Re: Launch tube question

Post by rockets-in-brighton » Fri May 15, 2009 5:59 pm

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
Rockets-in-Brighton
WEB: http://groups.google.co.uk/group/rockets-in-brighton

User avatar
Batkiter
Senior Member
Senior Member
Posts: 112
Joined: Fri Jun 20, 2008 8:07 am

Launch tube question

Post by Batkiter » Sat May 16, 2009 11:41 am

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
You do not have the required permissions to view the files attached to this post.



User avatar
U.S. Water Rockets1
WRA2 Member
WRA2 Member
Posts: 1771
Joined: Sat Feb 03, 2007 3:24 pm

Re: Launch tube question

Post by U.S. Water Rockets1 » Sat May 16, 2009 9:55 pm

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.


Team U.S. Water Rockets
Visit USWaterRockets.com
Visit our Blog
Tune in to our YouTube Channel
Visit our Facebook page
Visit our Twitter Page
Opportunity is missed by most people because it is dressed in overalls and looks like work. --Thomas Edison

User avatar
U.S. Water Rockets1
WRA2 Member
WRA2 Member
Posts: 1771
Joined: Sat Feb 03, 2007 3:24 pm

Re: Launch tube question

Post by U.S. Water Rockets1 » Sat May 16, 2009 10:07 pm

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.


Team U.S. Water Rockets
Visit USWaterRockets.com
Visit our Blog
Tune in to our YouTube Channel
Visit our Facebook page
Visit our Twitter Page
Opportunity is missed by most people because it is dressed in overalls and looks like work. --Thomas Edison

User avatar
rockets-in-brighton
Senior Member
Senior Member
Posts: 431
Joined: Fri Jun 20, 2008 12:33 pm

Re: Launch tube question

Post by rockets-in-brighton » Mon May 18, 2009 6:45 pm

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
Rockets-in-Brighton
WEB: http://groups.google.co.uk/group/rockets-in-brighton

User avatar
Batkiter
Senior Member
Senior Member
Posts: 112
Joined: Fri Jun 20, 2008 8:07 am

Re: Launch tube question

Post by Batkiter » Tue May 19, 2009 6:32 am

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)



dongfang
WRA2 Member
WRA2 Member
Posts: 210
Joined: Thu Jun 19, 2008 6:29 pm

Re: Launch tube question

Post by dongfang » Wed May 20, 2009 11:09 am

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



User avatar
Batkiter
Senior Member
Senior Member
Posts: 112
Joined: Fri Jun 20, 2008 8:07 am

Re: Launch tube question

Post by Batkiter » Wed May 20, 2009 11:33 am

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



User avatar
WRA2
Site Admin
Site Admin
Posts: 1079
Joined: Sat Dec 30, 2006 11:30 pm

Re: Launch tube question

Post by WRA2 » Wed May 20, 2009 4:06 pm

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,
:WRA2: Forum Administrator. :WRA2:
:WRA2:The Water Rocket Achievement World Record Association :WRA2:

User avatar
Tim Chen
WRA2 Member
WRA2 Member
Posts: 871
Joined: Wed Jan 31, 2007 1:44 am

Re: Launch tube question

Post by Tim Chen » Thu May 21, 2009 8:30 am

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!


Tim Chen
Captain, Team Enterprise

User avatar
U.S. Water Rockets1
WRA2 Member
WRA2 Member
Posts: 1771
Joined: Sat Feb 03, 2007 3:24 pm

Re: Launch tube question

Post by U.S. Water Rockets1 » Sat May 23, 2009 10:45 pm

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.


Team U.S. Water Rockets
Visit USWaterRockets.com
Visit our Blog
Tune in to our YouTube Channel
Visit our Facebook page
Visit our Twitter Page
Opportunity is missed by most people because it is dressed in overalls and looks like work. --Thomas Edison

Post Reply