What PSI have you achieved with meld launcher?

[sletts02]

What's the typical PSI you achieve with a meld/bump style PVC launcher (where you heat the section of PVC to create a small friction seal).

I seem to be stuck around 60psi, maybe my bump isn't uniform enough? I'm wanting to try a higher pressure but not sure if it's even feasible with this style launcher.

Enlighten me !

[U.S. Water Rockets1]

What's the typical PSI you achieve with a meld/bump style PVC launcher (where you heat the section of PVC to create a small friction seal).

I seem to be stuck around 60psi, maybe my bump isn't uniform enough? I'm wanting to try a higher pressure but not sure if it's even feasible with this style launcher.

Enlighten me !

Why not just make an o-ring launcher? They can handle 100's of PSI with PVC, and a lot more with metal launch tubes. It's not difficult, and we have some tutorials on how to do it on our YouTube Channel. Don't count out the design.

[sletts02]

What's the typical PSI you achieve with a meld/bump style PVC launcher (where you heat the section of PVC to create a small friction seal).

I seem to be stuck around 60psi, maybe my bump isn't uniform enough? I'm wanting to try a higher pressure but not sure if it's even feasible with this style launcher.

Enlighten me !

Why not just make an o-ring launcher? They can handle 100's of PSI with PVC, and a lot more with metal launch tubes. It's not difficult, and we have some tutorials on how to do it on our YouTube Channel. Don't count out the design.

I tried 3 times with no success with the o-ring unfortunately. Each time it seems to leak air. Perhaps I don't have the right sized / quality of o-ring?

I've tried every applicable o-ring from this pack: http://www.bunnings.com.au/kinetic-asso ... k_p4920305 All of them leak to some degree.

I tried the another meld/bump and got to 90P psi today which was good.

[bugwubber]

The first launcher I made used this method. Don't think I ever went over 65 without having to hold the rocket down. I recall someone heated up the pvc and then force screwed in steel male NPT fitting to produce a better ramped swell in the PVC.

From my own experience, the ideal o-ring for 1/2" pvc has been the type BUNA N size "-208" hardness 75 DN o-ring. Never had an issue with leaking up to 110psi.

[Blenderite]

Personally I have never had a problem with the o-ring style launcher. Do you have pictures of the one you built?

As for the bump launcher, I have not heard people using it past 90psi.