gardena rocket launcher

Water Rockets NSW

Moderator: Moderators

team-DH
Rocket Onlooker
Rocket Onlooker
Posts: 9
Joined: Sat May 16, 2009 1:32 am

gardena rocket launcher

Postby team-DH » Mon Aug 03, 2009 6:44 pm

hello all i got a problem with the gardena rocket launcher that george has build to launch many of his rockets u use a bottle cap to set the gardena in there is the problem i got we dont have the right bottle caps in the nederlands if tried to gleu the gardena on the bottle it self but that wont hold the pressure i use the launch them always there is 1 small leak in the nozzle of the gardena so do u guys now how to fix this problem that would be great thats just the only problem i got :)

air.command
Astronaut
Astronaut
Posts: 1887
Joined: Mon May 14, 2007 11:18 am
Location: Sydney, Australia
Contact:

Re: gardena rocket launcher

Postby air.command » Mon Aug 03, 2009 9:40 pm

team-DH wrote:hello all i got a problem with the gardena rocket launcher that george has build to launch many of his rockets u use a bottle cap to set the gardena in there is the problem i got we dont have the right bottle caps in the nederlands if tried to gleu the gardena on the bottle it self but that wont hold the pressure i use the launch them always there is 1 small leak in the nozzle of the gardena so do u guys now how to fix this problem that would be great thats just the only problem i got :)


Hi team-DH,

Could you please post a picture(s) of the nozzle/cap you are having trouble with? It is much easier to see where the problem might be.

What type of cap are you using? Does it have a separate internal plastic seal, or is it one of the new recent lids where the seal is made up entirely of the one piece?

What do you use as the seal? If the plastic isn't working, try making up a washer from a sheet of hard rubber (or trim down an existing washer)

You really should not need glue to seal the nozzle. The caps being made of polypropylene are hard to glue anyway so even at relatively small pressures the glue can come off.

To try to get a good seal between the nozzle and bottle check the following:

* The part of the gardena nozzle that seats against the bottle is flat and has no scratches on it.

* There is no dirt or plastic shavings on the seal, the nozzle and the bottle.

* The plastic/rubber seal between the nozzle and bottle needs to sit flat. Make sure it is not deformed when you tighten it or pushed to one side. If it is bunching up try adding a little silicone grease to the surfaces.

* Make sure the bottle cap is tight, but not over-tight. If it is too tight you will see the sides of the cap bulge out and may see lighter colour stress marks on the outside where the threads are.

* When putting the nozzle on the bottle keep the nozzle vertical rather than horizontal. This makes sure the seal in the nozzle does not fall to one side when you put it on.

If that still does not work, try looking for caps from other products, not necessarily from fizzy drinks. A lot of cleaning products have a longer and uninterrupted threaded caps that will fit the standard bottle. These are typically a better choice than a standard cap. You would need to have a look at your local supermarket to see what they have. The pump packs for soaps and hand lotions also have good caps. The hole they already have in the middle is fine for nozzles though you may need to make it a bit bigger.

Even though we have used these nozzles extensively, we still sometimes get a leak between the nozzle and bottle. This normally comes down to pinched rubber washer. We simply loosen the cap and re-tighten it to fix the problem.

By not gluing the nozzle to the bottle, you can easily swap the nozzle between rockets.

- George
Crop Circles: ... just a bunch of guys looking for their rockets ....

team-DH
Rocket Onlooker
Rocket Onlooker
Posts: 9
Joined: Sat May 16, 2009 1:32 am

Postby team-DH » Mon Aug 03, 2009 11:36 pm

tank u george sorry but i cant put any picture of the rocket or the bottle cap my camera is broken like hell and i need to the money to buy a new yes here it comes :) camera for imaging planets and the moon fotograping things with my telescope is a big hobby of me water rockets to :D i will explain the problem to as best as i can the problem is the the cap of the bottle its a new cap just as u said in ur reply of my supject the plastic washer is just 1 piece with the bottle and u canot get it off i was just looking for some new brands looks like a store sell them here they got the right bottle caps but still with the washer stuck inside of it also what tool do u use to get the tread section off on the nozzle ? sorry for my bad spelling dislextic

air.command
Astronaut
Astronaut
Posts: 1887
Joined: Mon May 14, 2007 11:18 am
Location: Sydney, Australia
Contact:

Postby air.command » Wed Aug 05, 2009 1:16 pm

team-DH wrote:tank u george sorry but i cant put any picture of the rocket or the bottle cap my camera is broken like hell and i need to the money to buy a new yes here it comes :) camera for imaging planets and the moon fotograping things with my telescope is a big hobby of me water rockets to :D i will explain the problem to as best as i can the problem is the the cap of the bottle its a new cap just as u said in ur reply of my supject the plastic washer is just 1 piece with the bottle and u canot get it off i was just looking for some new brands looks like a store sell them here they got the right bottle caps but still with the washer stuck inside of it also what tool do u use to get the tread section off on the nozzle ? sorry for my bad spelling dislextic


hi Team-DH,

No worries if you can't post a photo. I know of three kinds of caps commonly used on bottles.
1. The ones that are made from a single piece of plastic including the seal
2. Ones that have the (usually) blue plastic seal welded into them.
3. Ones that have the blue plastic seal that can be easily removed from the cap.

You want to use the last (3.) type of cap. In Australia at least 'Coke' bottles are the last to use these, all other manufacturers have switched to types 1. and 2. Have a look if Coke still sells bottles with those caps and use the seals from them. They should work well with the Gardena nozzle.

What pressures do you pressurise your rockets to?

As far as removing the threaded section from the Gardena nozzle I used to use a hacksaw, and then file down the edges. (These days we just put it on the lathe and cut it off that way. )

Once you remove the thread and clean up the edges, put the nozzle down on some fine sandpaper on a flat surface and sand the top of the nozzle so it will sit completely flat against the bottle. Try to remove any scratches, ridges etc. and see if you can even polish it. The cleaner this surface is the better sealing results you will get.

Also make sure that the diameter of the nozzle that sits inside the cap is as wide as possible to give the bottle maximum area to sit against. If the diameter is too narrow, you risk the seal rolling off the edge when you tighten the bottle and then you would get a poor seal.

Image

Please let me know how you go with that.
Crop Circles: ... just a bunch of guys looking for their rockets ....

Bones
Engineer
Engineer
Posts: 821
Joined: Sun Jun 24, 2007 10:04 am
Location: Wauchope!
Contact:

Postby Bones » Wed Aug 05, 2009 11:09 pm

Probably a little premature, but in about 12 months the thread length on a large range of the PET bottles is going to be shortened. Not sure by how much, but the change might be critical for water rocket applications.

I will see what I can find out for you.
"You could give Aristotle a tutorial. And you could thrill him to the core of his being ... Such is the privilege of living after Newton, Darwin, Einstein, Planck, Watson, Crick and their colleagues." - Richard Dawkins

www.suburbanrocketry.com

team-DH
Rocket Onlooker
Rocket Onlooker
Posts: 9
Joined: Sat May 16, 2009 1:32 am

oops

Postby team-DH » Thu Aug 06, 2009 3:07 am

sorry made a new topic wen i wanted to post a reply just look there :shock:

team-DH
Rocket Onlooker
Rocket Onlooker
Posts: 9
Joined: Sat May 16, 2009 1:32 am

name

Postby team-DH » Thu Aug 06, 2009 3:08 am

its named tank u guys 8)

air.command
Astronaut
Astronaut
Posts: 1887
Joined: Mon May 14, 2007 11:18 am
Location: Sydney, Australia
Contact:

Postby air.command » Thu Aug 06, 2009 7:53 am

Bones wrote:Probably a little premature, but in about 12 months the thread length on a large range of the PET bottles is going to be shortened. Not sure by how much, but the change might be critical for water rocket applications.

I will see what I can find out for you.


Hi Bones,

Good to know. On our last visit to the US I noticed that some manufacturers had introduced these smaller caps already, and my first reaction too was that it will become a problem. I guess by taking a couple of mm off the cap, hundreds of thousands of dollars can be saved.

I've been stock piling lids since, for when they are no longer available.

Luckily there are still lids from other products (various cleaning products) with much longer and un-interrupted threads that fit well on PET bottles.
Crop Circles: ... just a bunch of guys looking for their rockets ....

bpratt
Engineer
Engineer
Posts: 914
Joined: Sun Feb 10, 2008 3:20 pm
Location: Logan Village
Contact:

Postby bpratt » Thu Aug 06, 2009 8:49 am

air.command wrote:
I've been stock piling lids since, for when they are no longer available.



Just don't leave them where the sun gets to them, as they become perishable from the UV exposure.

:)


Return to “Air Command Water Rockets”

Who is online

Users browsing this forum: No registered users and 1 guest