Building from scratch; 7/16" ID bottle rockets.

[dagabu]

I have always loved bottle rockets and in my youth, I would buy them by the gross and have bottle rocket wars with my buddies in a quarry. I eventually grew up, got married and had kids but I can still never pass a fireworks store without grabbing at least a pack of standard bottle rockets to play with. Because of this unhealthy addiction to bottle rockets, I thought perhaps some immersion therapy would help me in getting past my addiction.

 

Lets start this project with a better understanding of how a bottle rocket is made and lets select a size to work with. Looking at all of the rockets that are available, I selected the Black Cat Three-Peat rocket with three reports to use as a template. The Black Cat Three-Peat rocket has a fuel grain .335" (about 8mm) wide and 1-3/8" (about 35mm) long and has 2.5g of black powder for fuel.

 

 

 

After shooting the pack of Black Cat rockets, I thought that I would like to make the same outer diameter rocket but I would like to use a larger fuel grain then the off the shelf variety and decided on a 7/16" or 0.4375" (about 11mm) by 2.00" (about 51 mm) long fuel grain made with granulated BP with 10% -325 atomized aluminum for a bright tail.

 

The tube I will use to make these is made from a strip of .30 chip board cut against the bias (it will naturally curl around the former with the grain going across the width) 8.5" long and 3" wide.

 

 

 

I then took a strip of chip board and sanded both ends of the chip board down to a fine taper. This makes for a very nice transition on both ends and makes a tight glue joint.

 

 

 

 

I use the 3M sanding screens (I have a crap load of them) to taper the ends like shown above. Look below and see the huge difference it makes in the end product. Look at the two on the far right. The taper makes for a round tube with no abrupt steps to the tube.

I then roll the strip up on a former WITH NO GLUE, straighten it out, tighten it up by rolling it toward the end on a flat surface with the palm of my hand and then glue only the last 1/2" (about 12mm). I then roll it closed and hold it against a flat surface to set the glue.

Here is the tube rolled up and ready to dry overnight.

Next up: Pressing nozzles and fuel into the tubes.

 

 

Well, I pressed the nozzle and BP to 5000LPI, the nozzle is a little crumbly and so I will be switching to kitty litter for these rockets.

 

 

 

The fuel grain has increased threefold to 6.2g of BP and with a 7/64" (.0109" or about 2mm) nozzle, there should be adequate thrust created to make the rocket and heading fly.

 

 

 

 

 

-dag

Edited November 5, 2011 by dagabu

[Blackthumb]

dag...I too share your love for the smaller rockets. I have been making them for years. Jus found 1000 5/8 x 3 solid tubes and am flying 'sawdust scooters' all over the place. They hold up so well, I have reused them when recovered...my thrifty side...find that I can reform the nozzle and load them many times before burnout. Of course I have to paint the sticks with day glo orange to find them easier but it is worth while. Like your labels.

[dagabu]

Thanks BT,

 

Why don't you post some pictures of how you make your rockets as well? These are great projects for winter and everyone here can make them.

 

-dag

[pyrokid]

Dag what kind of tooling do you use?

[dagabu]

I turned a stainless steel nipple and a couple aluminum rammers to make them.

 

-dag

[vh718]

nice little rockets dag, did you ever get that pm i send you for some tooling? Edited November 5, 2011 by vh718

[Blackthumb]

Dag...how do I embed photos into my reply such as you have?

[NightHawkInLight]

Very nice Dag, I look forward to seeing them fly. Good call on your tube rolling method also, they look good. Those small tubes hold up great with just the end glued down, and it saves a ton of time.

 

When you get them down I expect to see you recreate this:

 

http://www.youtube.com/watch?v=2Wir0qJdLYI

[dagabu]

Very nice Dag, I look forward to seeing them fly. Good call on your tube rolling method also, they look good. Those small tubes hold up great with just the end glued down, and it saves a ton of time.

 

When you get them down I expect to see you recreate this:

 

 

Nutter!

 

I am planning on a volley of 100 if I can swing it though. Video to follow.

 

Say, I had to glue them all the way, the loose chipboard got pulled down into the tube and screwed them up I also made a press in sleeve from Delrin and the process is going very smoothly now. The wind is howling tonight so Guy Fawkes night was a bust but I will see if I can't run out an light a few testers tomorrow night and get some video up here.

 

-dag

Edited November 6, 2011 by dagabu

[Col]

Hey dag,

Great pictures, you`ve sparked my interest in smaller calibre rockets so i knocked up some 1/2" tooling from some odds and sods i had around. It uses the extra long base as with my other spindles and fits the same base. My tubes will be a bit longer than yours at 85mm.

1/2" is smaller than i`m used to pressing and I managed to split 2 tubes testing how much nozzle mix to use ( turned out to be 2.5g) so i`ve had to make a support sleeve as well. I just need to pickup some small hose clamps for that and i`m in business.

I don`t have the patience to make 100 rockets at a time..2 or 3 and i`m ready for a teabreak

The spindle is 2" long

http://i770.photobucket.com/albums/xx341/colinspyro/2011/05inchrockettool.jpg

 

Quick update,

i pressed one to test. Specs: Fuel weight: 9.81g (75/15/10), motor weight: 19.27g, Stick length: 18". Added 1.25g of ti-spiked loose bp for a visual header. Total rocket weight: 26.9g incl the fuse.

http://i770.photobucket.com/albums/xx341/colinspyro/2011/readyforatest.jpg

Edited November 11, 2011 by Col

[dan999ification]

[quote

 

When you get them down I expect to see you recreate this:

 

http://www.youtube.com/watch?v=2Wir0qJdLYI

 

 

to be fair the brits hold the record for this,

col im suprised you got 2.5g nozzle in there i use .75 in my endburners [10mm] and 5g in the 1pound tubes i must get a small press.

and me too 2 or 3 and i start rushing things and need a break to slow me down.

 

dan.

[Col]

2.5g gives me a finished nozzle 1/2" tall, i alway inspect the first few nozzles by cutting them from the tube. I use 10g in 3/4" tubes.

I pressed a second motor so i have one to put on the scales for a thrust test and one to fly. It was way too windy last night.

 

I managed to do the thrust test. The little motor delivered a peak thrust of 3.55kg, or a shade under 8lbs. thrust test

Edited November 12, 2011 by Col

[spitfire]

Dag, compliments on your hard work! I think many pyro's share this warm feeling to small bottle rockets, for me it all started with these neat items as a kid when my father took me out for lighting some. Together with some fountains and ground spinners, i smelled the magic. In my memories, this particular moment was the trigger. Later as a kid, i cut up small Chinese bp bottle rockets, and i thought they where easy: no clay nozzle, just a crude crimped end, and the fuse creating an empty space for maximum pressure. Little did i know how difficult it turned out to be if you want to make your own. 1lb rockets, no problemo, but small bottle rockets with only 1g BP, going that high?? Gosh! Magic... hmm...