Water Rocket Forum

Last weekend I went to local stores in order to find materials for my first launcher. From the materials I bought I imagine the attached gardena launcher system intended to be portable. I will start to assemble it in the next days and hope it will work.

I am planing to use the super glue (Cyanoacrylate) instead of plastic glue to assemble the pvc pipes, I have the feeling that it will be more robust. Does anyone have experience with this super glue?

Thx for your comments

Howdy! I like your simple, compact design. One suggestion I have is that you consider putting the hinge to fold away from you so the pipe lays down on top, inside the c channel. That keeps all the lateral stress off of the pin and PVC. Might increase your base length.

I used Plumbers Goop on a joint that has held well for 5 years now. Recommend using the primer and glue designed specifically for pvc as they have excellent strength and gap filling qualities. If applied properly, it won't be the joint that fails first.

Super Glue is not the best option for PVC. For a stronger hold, and less chance of leakage, use PVC Cement (often called Camel Snot). You don't even need to use the primer, straight cement is good enough for most launchers. I've never had a PVC joint fail (in any project).

Like Tony, I've never used primer, and the pvc cement has always held. I do usually clean the parts with paint thinner, though. Apparently if you don't have the primer, you can give the parts a quick sanding with fine sand paper. I guess they used to do that before they developed the primer. Definitely recommend going with PVC cement.

Another thing about super glue- apparently it is slightly water soluble. If you use it for a launcher joint that gets wet, it could dissolve over time and eventually fail.

Hi bugwubber, Tony and SaskAlex

I am very glad that I posted here my project because you guys gave great suggestions on it.

bugwubber you are absolutely right, it would be much better that way and as mentioned the only problem is the bigger base that would compromise portability. I will surely think about it and probably will follow your suggestion.

Also Tony and SaskAlex thanks for your remarks on the glue. I will look for PVC cement.

Hope to start this project next Sunday.

Thanks again for your help!

That's good to hear about the primer cause that is some nasty stuff. I would not mind at all replacing that with a little sanding.

By all means, use the PVC cement if possible. It welds the PVC together and the parts fuse and cannot come apart. CA glue just makes a surface bond which can peel apart under load.

It is ready with your good suggestions. I have named it "Gardena-Soyuz" because it makes me remember the Soyuz launch pad (with the raising tower).

Now just need a nozzle and a rocket and then I will do two 15 min pressure tests: ~70 and ~100 psi. If it passes them (hope so ) ... first launch

However there is one thing that worries me. On this system I do not have non-return valve and the rocket will stay too high to make a S-bend with my Hand Pump hose, so I am worried to have water damaging the Hand Pump.
What is your experience on this? Do you think it will be a critical item? Is it really necessary?

Thx

nunopt wrote:It is ready with your good suggestions. I have named it "Gardena-Soyuz" because it makes me remember the Soyuz launch pad (with the raising tower).

Now just need a nozzle and a rocket and then I will do two 15 min pressure tests: ~70 and ~100 psi. If it passes them (hope so ) ... first launch

However there is one thing that worries me. On this system I do not have non-return valve and the rocket will stay too high to make a S-bend with my Hand Pump hose, so I am worried to have water damaging the Hand Pump.
What is your experience on this? Do you think it will be a critical item? Is it really necessary?

Thx

Beautiful! I've only used compressors so not able to comment on the hand pump question.

Suppose if it is an issue, you could just add a turn at the bottom of the pipe so your tire valve is pointed up. Then when you pour in water, some air will remain trapped in front of the valve.

I wouldn't worry about the water. Are you connecting the pump directly to the launcher, or do you have an air line in between? In any case, the water probably won't make it all the way back to the pump. Even if it does, I doubt there is anything in your pump that will be ruined by a little water. Does it have any steel parts? Of the pumps I've had, the cheap ones are all plastic, and the good one is all aluminum and maybe some brass. Nothing that will rust.

Just did the pressure test and at 70 psi ... 5 min ... booom ...

The white chair foot with the bike valve seems not to be pvc, there is no information at the package, but probably PE (??). As I could check (picture below), the pvc cement stayed well stuck to the pvc tube and not to the chair foot. The problem is that I could not find pvc ends at local stores.

Have to think about it ... look at the internet or go for other solution ...

Parabéns ! O seu lançador ficou muito bem e parece muito fácil de transportar e usar.
Não se sinta aborrecido pelo lançador ter explodido. Para que isso não aconteça, a cap (a peça que tem a válvula) deve ser de rosca e não colada.
Espero ter ajudado.
Contudo, você inspirou-me e acho que vou fazer um novo lançador... mais 'bonito', tal como o seu.

PTrockets

nunopt wrote:Just did the pressure test and at 70 psi ... 5 min ... booom ...

The white chair foot with the bike valve seems not to be pvc, there is no information at the package, but probably PE (??). As I could check (picture below), the pvc cement stayed well stuck to the pvc tube and not to the chair foot. The problem is that I could not find pvc ends at local stores.

Have to think about it ... look at the internet or go for other solution ...

That chair foot piece does look like PE plastic or something similar. This would be a likely material for a piece that takes a lot of abuse and impacts. You need to find some PVC pieces somewhere to make the repair. Good luck with the fix!

One of the primary qualities of PE is that it is slippery stuff. Very hard to glue.

Here's a closeup picture of my schrader valves. Bottom right is a slip fit PVC cap. Notice it is much thicker walled than the chair foot so it is able to handle higher PSI.

If you can't find that, check out the other solution at the top of the picture:
1/2" slip fit to female threaded PVC adapter, screwed into that is a brass reducer 1/2"NPT to 1/4", and finally a 1/4" male threaded schrader valve.
It costs a lot more to go that route, that's about $12us worth of brass there vs the $.30 slip fit cap and a free tire stem.

One last thought- threaded isn't necessary, but it makes it much easier to swap out the tire valve if it starts leaking. With glued on slip fit, you have to cut the cap off and toss it.

Many thanks for your great suggestions posted here!

Unfortunately local stores give me limited options, nevertheless instead of the pvc tube I decided to use a fiber reinforced hose with a pvc tube outside. To fix the bike valve I was going to use a clamp but I saw another part that gave me an idea, it was a cable gland and I gave it a try. The bike valve fits very well inside the gland and I screw it to the hose ( not the best solution .. but just to try).

It worked at 70 and 100psi .. but was loosing 1-2psi/min through the screw zone. So I assembly it again using glue and after repeating the two 15 min tests, was loosing only 0-0,2psi/min. I think I have a launcher

Afterwards just did a few improvements on it and now I have to build a rocket to launch. I still do not have one ..