Lasheyda wrote:Thanks a bunch! I have a couple of brass and plastic (irrigation PVC) nipples lying around, would love to put them to use!
Have you ever tried this yourself?
I would avoid the brass ones. They will unsettle the balance of the rockets and add unneeded weight.
Joining PET bottles is a huge advantage due to best air flow and minimal weight addition, but if you must use robinson coupling methods, stick to largest openings you can effectively apply. Pressure and water the same, the joined rocket should always beat out the coupled rocket, So keep that in mind.
Yes, I use irrigation nipples.
At this time, I like to keep my rockets modular, with interchangeable components.
I need to add a few comments on the process:
Careful how deep you tap, you want the thread as tight as possible.
If possible, tighten the bottles as an assy. while under some pressure, to include expansion and to set the bottoms firmly against each other.
Remember to apply your preferred adhesive to the inner side of the bottle.
(normal robinson process uses a seal between bottles.)
You may need to apply adhesive more than once.
There are no nuts used.
Done properly, you should be good to 110/120 psi
Nick and Dad B.