Restricted Nozzle Launcher

[Brian]

I recently built a launcher which is designed to seal onto the outside of a 16mm OD PVC pipe. The pipe has a 12mm ID.
Because the launcher seals from the outside, the inside can be restricted to any size desired.

Internal O-Ring

RIMG0051.JPG (162.66 KiB) Viewed 108 times

I played around with a 12mm and a 6mm nozzle and got an interesting flight out of the 6mm.

[youtube][/youtube]
I'll be testing cavitation and air water mix nozzles soon if it stops raining.

12mm Nozzle

12mm (1).JPG (52.92 KiB) Viewed 108 times

6mm Nozzle

RIMG0046.JPG (51.43 KiB) Viewed 108 times

Cavitation Nozzle

RIMG0049.JPG (53.82 KiB) Viewed 108 times

For more infomation http://ascenderwaterrockets.weebly.com/ ... ncher.html

[U.S. Water Rockets1]

I recently built a launcher which is designed to seal onto the outside of a 16mm OD PVC pipe. The pipe has a 12mm ID.
Because the launcher seals from the outside, the inside can be restricted to any size desired.

RIMG0051.JPG

I played around with a 12mm and a 6mm nozzle and got an interesting flight out of the 6mm.

[youtube][/youtube]
I'll be testing cavitation and air water mix nozzles soon if it stops raining.

12mm (1).JPG

RIMG0046.JPG

RIMG0049.JPG

For more infomation http://ascenderwaterrockets.weebly.com/ ... ncher.html

Hi Brian,

That is an interesting scheme you created for your launcher. How well does the internal o-ring hold up to launch forces? Usually o-rings on internal grooves tend to blow off under launches. We have experimented with PVC nozzles with internal o-rings on some of our early FTC rockets and we also used PVC to adapt odd sized bottles and jugs to fir our launcher. We would cut a PVC coupler that fits the launch tube and glue it into the bottle mouth to adapt the size. Your method could be used to adapt any bottle to your launcher as well, plus you can have practically any size nozzle opening you choose. That's a great idea.

[U.S. Water Rockets]

Bottle Neck Adapter

adapter.jpg (35.54 KiB) Viewed 102 times

This would be example of the neck adapter we created. The inside diameter matches the PVC pipe outside diameter so it will fit our cable tie launcher.

Brian, your idea goes quite a bit farther than simply adapting a bottle neck to a lunch tube. Nice job!

Either of these concepts would be good for people who lived in places where the bottle mouth opening doesn't fit well to the local PVC pipe.

[Brian]

Thanks, here's a diagram (better late than never)

Cross section

0-12mm.png (7.93 KiB) Viewed 86 times

I haven't had any problems yet. To get the o-ring right, I have to cut a 45 degree edge on 2 peices of pipe to a certain depth to form the groove for the o-ring to sit in.
I'll do some more testing soon

[U.S. Water Rockets1]

Thanks, here's a diagram (better late than never)

0-12mm.png

I haven't had any problems yet. To get the o-ring right, I have to cut a 45 degree edge on 2 peices of pipe to a certain depth to form the groove for the o-ring to sit in.
I'll do some more testing soon

Have you had any problems using the tie wrap heads trimmed off and used to clip the base of the launcher tie wraps? This looks like a nice way to hold the tie wraps in place. Are there any drawbacks with this method? We always assumed the tie wrap strength rating was based on the failing point of the ratchet lock, but never tested that theory.

[Brian]

Have you had any problems using the tie wrap heads trimmed off and used to clip the base of the launcher tie wraps?

No.
They probably are the weekest link but are OK for the pressures I work with (150psi). I usually put glue in the head of the cable ties just in case.

[atvan]

Neat! I would recommend bigger fins for the more restricted nozzles, because the smaller nozzle means that the weight remains in the back for longer, upsetting the stability of the rocket and likely causing the results seen with the 6mm nozzle.

[Brian]

Yes, but it is fun to watch. I don't see any real need for a 6mm nozzle in a single stage rocket though.

[U.S. Water Rockets1]

Neat! I would recommend bigger fins for the more restricted nozzles, because the smaller nozzle means that the weight remains in the back for longer, upsetting the stability of the rocket and likely causing the results seen with the 6mm nozzle.

If you use a level and get the launcher pointed exactly straight up, the rockets tend to balance on their tails as they launch and take some time to start tipping. This gives enough time for the fins to catch air.