Water Rocket Forum

I've retired the PVC design (the kids want to use lots of different kinds of fuels and it seems that the PVC meld/o-ring is equipped to handle it).

I've now followed a tutorial for a gardena style launcher - but - it seems like the guide rails need to be put on each rocket. Is there a design that has the guide-rail that comes through the nozzle similar to the PVC pipe designs? I think I've seen one somewhere, but I may be mistaken.

Many thanks!

As far as I am aware, an internal guide rail, which is basically a more complicated launch tube system, require custom pieces to create, especiallysince the launch tube (guide rail) has to be small enough to fit inside the Gardena nozzle.

Also, if you put guides on the rockets, it makes the rocket heavier and therefore not go as high. Plus, if you only use one it can make the rocket tilt in flight.

Personally, I think Air Command nailed it.

That would be a much easier build and probably more durable too.

Hello DogLover,

I used both 9mm and 15mm Gardena Nozzles. I have heard that a launch tube is more appropriate for larger nozzles such as the fullbore and 15mm. The 15mm Nozzle is a convenient size as you can buy 15mm Copper Tubing that fits very nicely into the Gardena Release head and doesn't even need to be Epoxied into place as there is a firm fitting. Plus it can be removed and other lengths put in for smaller/larger rockets.
As for the 9mm standard gardena nozzle, it would be the same principle although as far as I am aware 9mm is not a standard size for Copper Tubing where I live, but it may be in the USA as I am sure there are much better shops there!! So if you can find it great!

However the technique I use as a launch tube wouldn't be suitable for an internal Guide Rail as the tube preferable needs to be Epoxied into place. Because I prefer to make the launch tubes interchangeable. I instead use a curtain rail as the guide rail and simply attach the small clips to the fairings of the rocket (which weigh less than a gram each). This works quite well. But if you found 9mm tubing and Epoxied it in place it would work well as an internal guide rail. Just make sure to use furniture polish to reduce friction as it much get pulled out by the rocket at launch and that would not be good!
(this final photo was taken prior to painting the launcher)

Hope that Helps, Jamie B.

Jamie5335 wrote:Hello DogLover,

I used both 9mm and 15mm Gardena Nozzles. I have heard that a launch tube is more appropriate for larger nozzles such as the fullbore and 15mm. The 15mm Nozzle is a convenient size as you can buy 15mm Copper Tubing that fits very nicely into the Gardena Release head and doesn't even need to be Epoxied into place as there is a firm fitting. Plus it can be removed and other lengths put in for smaller/larger rockets.

jamie_20140630_0113 c.jpg

jamie_20140701_0130 c.jpg

As for the 9mm standard gardena nozzle, it would be the same principle although as far as I am aware 9mm is not a standard size for Copper Tubing where I live, but it may be in the USA as I am sure there are much better shops there!! So if you can find it great!

However the technique I use as a launch tube wouldn't be suitable for an internal Guide Rail as the tube preferable needs to be Epoxied into place. Because I prefer to make the launch tubes interchangeable. I instead use a curtain rail as the guide rail and simply attach the small clips to the fairings of the rocket (which weigh less than a gram each). This works quite well. But if you found 9mm tubing and Epoxied it in place it would work well as an internal guide rail. Just make sure to use furniture polish to reduce friction as it much get pulled out by the rocket at launch and that would not be good!

jamie_20140630_0115 - Copy.JPG

DSC01723 - Copy.JPG

(this final photo was taken prior to painting the launcher)

Hope that Helps, Jamie B.

Hey Jamie!

I've invested in some 15mm/18mm OD gardena's and some copper tube which seems like it will work a treat as an internal guide. I'm thinking to just hose clamp the hose to the copper tube - easy.

In terms of the 9mm/12mm nozzles I'm at a loss. I went to Bunnings (hardware) today and I couldn't find anything that would work as an internal guide, back to the drawing board for that one!

Thanks for the great ideas!

Jamie5335 wrote:Hello DogLover,

I used both 9mm and 15mm Gardena Nozzles. I have heard that a launch tube is more appropriate for larger nozzles such as the fullbore and 15mm. The 15mm Nozzle is a convenient size as you can buy 15mm Copper Tubing that fits very nicely into the Gardena Release head and doesn't even need to be Epoxied into place as there is a firm fitting. Plus it can be removed and other lengths put in for smaller/larger rockets.

jamie_20140630_0113 c.jpg

jamie_20140701_0130 c.jpg

As for the 9mm standard gardena nozzle, it would be the same principle although as far as I am aware 9mm is not a standard size for Copper Tubing where I live, but it may be in the USA as I am sure there are much better shops there!! So if you can find it great!

However the technique I use as a launch tube wouldn't be suitable for an internal Guide Rail as the tube preferable needs to be Epoxied into place. Because I prefer to make the launch tubes interchangeable. I instead use a curtain rail as the guide rail and simply attach the small clips to the fairings of the rocket (which weigh less than a gram each). This works quite well. But if you found 9mm tubing and Epoxied it in place it would work well as an internal guide rail. Just make sure to use furniture polish to reduce friction as it much get pulled out by the rocket at launch and that would not be good!

jamie_20140630_0115 - Copy.JPG

DSC01723 - Copy.JPG

(this final photo was taken prior to painting the launcher)

Hope that Helps, Jamie B.

Hey Jamie!

I've invested in some 15mm/18mm OD gardena's and some copper tube which seems like it will work a treat as an internal guide. I'm thinking to just hose clamp the hose to the copper tube - easy.

In terms of the 9mm/12mm nozzles I'm at a loss. I went to Bunnings (hardware) today and I couldn't find anything that would work as an internal guide, back to the drawing board for that one!

Thanks for the great ideas!

sletts02 wrote:Hey Jamie!

I've invested in some 15mm/18mm OD gardena's and some copper tube which seems like it will work a treat as an internal guide. I'm thinking to just hose clamp the hose to the copper tube - easy.

In terms of the 9mm/12mm nozzles I'm at a loss. I went to Bunnings (hardware) today and I couldn't find anything that would work as an internal guide, back to the drawing board for that one!

Thanks for the great ideas!

I hope that you have a non-return valve in your design. If you don't then your pump will be destroyed. Trust me I have done it before.

As for the 9mm tubing, I think that this might work: http://www.hobbylinc.com/htm/k+s/k+s9827.htm It comes with two 12" pieces, that should be enough for a launchtube.

DogLover wrote:

sletts02 wrote:Hey Jamie!

I've invested in some 15mm/18mm OD gardena's and some copper tube which seems like it will work a treat as an internal guide. I'm thinking to just hose clamp the hose to the copper tube - easy.

In terms of the 9mm/12mm nozzles I'm at a loss. I went to Bunnings (hardware) today and I couldn't find anything that would work as an internal guide, back to the drawing board for that one!

Thanks for the great ideas!

I hope that you have a non-return valve in your design. If you don't then your pump will be destroyed. Trust me I have done it before.

As for the 9mm tubing, I think that this might work: http://www.hobbylinc.com/htm/k+s/k+s9827.htm It comes with two 12" pieces, that should be enough for a launchtube.

What non-return valve do you recommend? I've seen the two on YouTube that use a piece of rubber, is that the only way? Would this be a better option? http://www.bunnings.com.au/holman-20mm- ... -_p4790027

That H&S stuff looks like a winner, but it's hard to get a hold of in Aus by the looks of it.

I found some 10mm aluminum at Bunnings today. I drilled out the gardena nozzle and adapter to make it fit nice.

I'm not sure if it will be a long enough guide with a single bottle. I'm thinking it'll only work with a spliced bottle with a longer rail. Thoughts?

Hello sletts02,

Sorry for my late reply, I am on holiday and making use of WiFi hotspots!

Glad you found my post helpful! As for the 9mm nozzle launch tube, that is a good idea to drill it out and make it 10mm as you can buy that as a standard size so I might have to give that a go!

As for the non return valve, Dog lover is right, you do need one and I found this out due to the fact that the Schrader valve (a bicycle pump valve) isn't non return above around 30psi. So when I got the new compressor, we went down to our local hydraulics/plumbing store and drew out a diagram of what we wanted to do (make a new launcher using the gardena). Although we got some strange looks, the people in the shop were very helpful and found all the parts and it worked as planned. I myself have little experience in plumbing, so your local plumbers merchant would be your best bet in integrating a non return valve into your launcher.

Hope that helps, Jamie B.

Jamie5335 wrote:Hello sletts02,

Sorry for my late reply, I am on holiday and making use of WiFi hotspots!

Glad you found my post helpful! As for the 9mm nozzle launch tube, that is a good idea to drill it out and make it 10mm as you can buy that as a standard size so I might have to give that a go!

As for the non return valve, Dog lover is right, you do need one and I found this out due to the fact that the Schrader valve (a bicycle pump valve) isn't non return above around 30psi. So when I got the new compressor, we went down to our local hydraulics/plumbing store and drew out a diagram of what we wanted to do (make a new launcher using the gardena). Although we got some strange looks, the people in the shop were very helpful and found all the parts and it worked as planned. I myself have little experience in plumbing, so your local plumbers merchant would be your best bet in integrating a non return valve into your launcher.

Hope that helps, Jamie B.

Bicycle tires use schrader valves in a non return configuration well over 30PSI. Are you sure you simply did not have a pump that utilized this feature? Some bike pumps have a barb that defeats the return function intentionally to make pumping easier but when the pump is removed from the valve, the return valve is allowed to close normally. This works with tires with over 100PSI in them.

For a 9mm Gardena guide rail/internal launch tube I use 3/8" (9.525 mm) automotive brake line and mount it in the launcher using a standard compression fitting and bore the nozzle to 3/8" by hand. I don't use epoxies and such with my launchers as it is difficult to have an accurate idea of the maximum safe psi over time with the stress of all the rapid pressure cycling.

MarcTolbert wrote:For a 9mm Gardena guide rail/internal launch tube I use 3/8" (9.525 mm) automotive brake line and mount it in the launcher using a standard compression fitting and bore the nozzle to 3/8" by hand. I don't use epoxies and such with my launchers as it is difficult to have an accurate idea of the maximum safe psi over time with the stress of all the rapid pressure cycling.

How stiff is that brake line? Will it get all bent up when the rocket launches?

U.S. Water Rockets1 wrote:

MarcTolbert wrote:For a 9mm Gardena guide rail/internal launch tube I use 3/8" (9.525 mm) automotive brake line and mount it in the launcher using a standard compression fitting and bore the nozzle to 3/8" by hand. I don't use epoxies and such with my launchers as it is difficult to have an accurate idea of the maximum safe psi over time with the stress of all the rapid pressure cycling.

How stiff is that brake line? Will it get all bent up when the rocket launches?

I get the straight lengths of steel pre-flared with connectors on the line. They are quite stiff and the walls are very thick for the diameter (my sons have misplaced my digital calipers). I cut a fresh section of line to the length I need and mount it using a brass compression fitting. A forty inch length of brake line is under 7 USD. I have not had problems with any bending with launches at up to 250 PSI and internal launch tube lengths of up to 14".

How it does with in longer lengths and higher pressures is still to be determined. You would definately be the resident expert on really long internal launch tube lengths at very high pressures. What have you been using for your FTC rockets?

I had a quick look at my old pump and it looks like it does have some type of barb in it, that defects the Non return. My mistake Though I wouldn't trust a Schrader valve on a 200 PSI rocket! I would invest in a more professional air line just to be safe when dealing with those pressures!

Cheers Jamie B

Jamie5335 wrote:I had a quick look at my old pump and it looks like it does have some type of barb in it, that defects the Non return. My mistake Though I wouldn't trust a Schrader valve on a 200 PSI rocket! I would invest in a more professional air line just to be safe when dealing with those pressures!

Cheers Jamie B

We had a regular automotive shrader valve hold 290PSI for several minutes before it failed, and the failure was that it popped out of the PVC pipe. Had we used the correct drill size for the hole it probably would have stayed put.

[youtube][/youtube]