Greetings From Colorado!

[Jtrops]

I am a high school art teacher, and I had an idea to do a rocket project in my crafts class. I ran into a bit of interference on solid fuel rockets, and then I remembered water rockets from when I was a kid. After a brief search on the web I found this forum, and I'm all over it.

I made a Gardena launcher with a few bits that I had floating around. I'm using a bicycle lever with a long run of cable to trigger the mechanism. I have a 1L. bottle that I did a test with and it worked flawlessly. I can't wait until next weekend when I have fins and a nose cone on the bottle.

I fitted the male Quick Connector to the bottle by shrinking the bottle threads just a little (boiled for a few seconds), then the connector threads right on without a hitch. This is certainly going to be a fast and easy way to do it with 30 kids in my class. I only tested it to 60psi, but there were no leaks.

I'm so excited about this that I may bail on my Estes kit. Those rocket engines are expensive anymore.

[bugwubber]

Howdy and welcome to the forum!

That is a great solution to the gardena nozzle thread issue. Certainly beats drilling and gluing bottle caps for speed. Probably the lightest weight version as well.

I went the other way for nozzles- I chose full bore so there'd be no need to modify bottles. I then built a launcher that sends off 5 at a time. My "class" was 200 Cubscouts and we had to build and launch up to 30 rockets per 40min rotation. Surprisingly, we were able to launch everyone's rockets at least twice during that time window.

I don't blame you regarding estes. Maybe you could find out if a Tripoli club launches nearby and attend one of their high power launch events?

[Jtrops]

Wow, 30 rockets in 40 minutes! I'm planning on a couple of launchers, but I have an hour and a half to setup, launch tear down, and get my class back to the building.

After my initial search I was planning on doing the full bore method with my class. Then I saw the Gardena nozzle and I realized that I had all of that stuff at home already. When I put it together I was still thinking of doing full bore for school until I came up with the idea to boil the threads. That makes the Gardena a fast and easy option, although more expensive.

I think we will only need the nozzles since everything else will be either scavenged, or materials left over from other projects. Has anyone had luck with craft foam fins? I'm still trying to figure out a source to get the corrugated plastic, but I've got plenty of craft foam

Water rockets appeal to the scavenger in me. My solid fuel rocket launch system is pretty scavenged as well. I'm considering modding it to launch water rockets. Of course my gel cell launch controller won't have much use.

[bugwubber]

Wow, 30 rockets in 40 minutes! I'm planning on a couple of launchers, but I have an hour and a half to setup, launch tear down, and get my class back to the building.

After my initial search I was planning on doing the full bore method with my class. Then I saw the Gardena nozzle and I realized that I had all of that stuff at home already. When I put it together I was still thinking of doing full bore for school until I came up with the idea to boil the threads. That makes the Gardena a fast and easy option, although more expensive.

I think we will only need the nozzles since everything else will be either scavenged, or materials left over from other projects. Has anyone had luck with craft foam fins? I'm still trying to figure out a source to get the corrugated plastic, but I've got plenty of craft foam

Water rockets appeal to the scavenger in me. My solid fuel rocket launch system is pretty scavenged as well. I'm considering modding it to launch water rockets. Of course my gel cell launch controller won't have much use.

There are a couple battery powered options for water rocket launchers- either HD servos or 12v car door lock solenoids.

My rocket using box fin design that US Water Rockets came up with. These are made from cardboard.

CAM01145.jpg (3.24 MiB) Viewed 25 times

For fin material, a lot of my fins are 1/4" plywood triangles which were scraps left over from another Scout project. Duct tape covered cardboard make great fins. I've used foamcore posterboard on our water rocket bobsled shells and it worked really well- that was covered in duct tape as well. If you are using glue to put the fins on, thicker material holds in place better than thin and there's no need for filets.

Are far as scavenging, yeah me too. We shop at buy-n-large so we get a bunch of cardboard boxes that had been getting stuffed in the recycle bin. Now they are being cut into strips to use as fins. A bedframe, fenceposts, broken windchime, carpet cleaner bottle caps, wood blind slat cutoffs, old carbon arrow shafts, and various garden hose fittings have all been integrated into my water rockets or launchers.

[Jtrops]

That's a cool fin arrangement. It looks fairly easy to make, probably the math to get the opening tight around the bottle is the hardest part. Does the plywood help to reinforce the bottle so that it holds more pressure?

I thought for my class that I would have the students research different fin configurations, and then design their own. Since it's not a science class I don't plan on hitting the physics too hard. Still we will have awards for highest flight, lowest flight, most stylish fins, most inventive design, and a few more. I hope to have the students come up with ideas and make the awards.

Fins are going on today. I will see what I can scavenge.

[bugwubber]

That's a cool fin arrangement. It looks fairly easy to make, probably the math to get the opening tight around the bottle is the hardest part. Does the plywood help to reinforce the bottle so that it holds more pressure?

I thought for my class that I would have the students research different fin configurations, and then design their own. Since it's not a science class I don't plan on hitting the physics too hard. Still we will have awards for highest flight, lowest flight, most stylish fins, most inventive design, and a few more. I hope to have the students come up with ideas and make the awards.

Fins are going on today. I will see what I can scavenge.

The math is just 2D*.866 Here's their instructions- http://www.uswaterrockets.com/construct ... torial.htm

The plywod does not have an impact on bottle pressure capacity.

You can do things like wrap the bottle in duct tape, fiberglass, or even something exotic like carbon fiber or kevlar but I haven't bothered much with that yet. My pet project is a 5 minute splice. Not quite there yet.

One of the main factors in a successful rocket is to get the mass and cg right. Single bottle rockets especially need weight in the nose to fly right.

You can have a lot of fun with the fins and do a retro 50's style if you have clearance on your launcher.

[Jtrops]

My first launcher was thrown together in 20 minutes with a goal of proving the concept. Since it works my next goal is to make it more practical. I plan on putting an air tube through the Gardena fitting so that it has a guide rod inside, and still uses the quick connect. My thought is that this will free up space around the launcher for creative fin designs without having to worry about the launch rod/lugs.

Good point about the weighted nose. I will probably have to hit on stability a bit. It will be fun seeing all of the students swinging rockets around on string. To be honest it's been a long time since I've thought this much about rockets.

[bugwubber]

My first launcher was thrown together in 20 minutes with a goal of proving the concept. Since it works my next goal is to make it more practical. I plan on putting an air tube through the Gardena fitting so that it has a guide rod inside, and still uses the quick connect. My thought is that this will free up space around the launcher for creative fin designs without having to worry about the launch rod/lugs.

Good point about the weighted nose. I will probably have to hit on stability a bit. It will be fun seeing all of the students swinging rockets around on string. To be honest it's been a long time since I've thought this much about rockets.

That is the great thing about gardena launchers. They can be made quickly without any glues or solvents. You just have to figire out how to stick the nozzle on the bottle. My first test attempts were similar except I used an airhose quick release glued into a soakerhose endcap. I then realized I had a pvc launcher already 90% built with a pvc sprayer I had made a couple years before.

I just got invited to help the 5th grade launch water rockets at my kid's school. This should be fun because they have been launching them only 20-30ft in the air.

[Jtrops]

I suppose I should jump over to the regular forums, but this is a nice discussion happening here in the "introduction" forum.

Anyway, I am running into a glitch with my launcher release, and I have some questions about emergency pressure valves.

My remote release works as long as the run is 8' or less. once it gets longer than that the cable has to much friction inside the housing to move smoothly, and by the time the gardena is pulled it's not enough to release the nozzle. I was hoping to have a launcher that would not have to supply resistance to the line in order to activate the launch. Are there any work arounds for this or is the best solution to make the launcher base bigger, and stake it down so that it can resist the pull?

My biggest concern is being able to launch from the 50' distance mentioned on the safety page. Is this distance for high pressure rockets, or for all air rockets? I don't imagine going over 100psi for our school launches.

Secondly, I am trying to figure out a simple emergency release valve. Is there anything out there that has a pin that when pulled out opens a valve? I would imagine that the amount of force to pull the pin would be fairly insignificant. I can imagine how a valve like this might work, but I haven't found anything.

[bugwubber]

I wonder if a lubricant would help out your cable. Maybe graphite or a chain wax from a bicycle shop or synthetic grease if it has already been greased?

Regardless you should always stake your launcher. The conventional solution is to just put eyebolts or pulleys at the base of your launcher to minimize tipping forces.

I don't recall ever seeing this type of cable release stretched out to 50ft so you may have found why...

50ft- yes adhere to it. Kids will have a tendancy to crowd the launcher if they aren't kept back. Not just for burst danger but what goes up can come down just as fast. Also, you get a better view of the launch.

Do I personally violate the 50ft rule? Yes. Not at Scout/Student events though.