Roman Candle Redux - 4 Shot, 7 mm Mixed Candle
Date: 2006-05-05
Description
It has been a while since I made a roman candle. All my previous efforts were hampered by my poor quality lift, but lately I've been making much better quality corned BP.
Over the past few weeks I've rolled some 7 mm ID tubes with mini-candles in mind, and pumped an assortment of 5 mm stars with various comps. So all the materials were at-hand, except for candle composition. I decided to try some granulated 6:1:1 BP (made from commercial airfloat) I had in the magazine rather than make a batch of candle comp up and wait a few more days while it dried.
The tubes were rolled using wheat paste and 80 gsm A4 copy paper, rolled on a length of brass tube. They were pasted for the first few turns and the last, Weingart style, but the rolling spread the paste so that all the paper was pasted to some degree. The off-cut from making a small stargun was selected for this initial test, it was one of the poorest tubes, it got wrinkled a little during rolling but the damage was largely cosmetic. At only 130 mm long, 4 shots was about the limit with a good delay between them. The bottom plug was paper wadding and hot-melt glue because I currently lack a nipple and rammer matching the tube ID.
A small powder scoop was made using a piece of soda straw hot-melt glued to a length of rectangular bamboo stick. Its dimensions are approximately 5 mm ID and 3 mm deep. The lift is corned -10+30 mesh from very hot BP.
I used the clay scoop from my old 9.5 mm payload lifter rockets for the candle comp. All stars were 5 mm OD, 8 mm long. The stars in shot order were; Winokur 20, Chlorate Red, D1 Glitter, Tiger Tail.
A short length of visco was used to fuse the candle, held in place with a thin nosing of kitchen paper. A bambo kebab stick was hot-melt tacked to the side as a stake.
Comments
Worked great!
Unfortunately the video does not follow the stars in the air, but the performance of the device can still be roughly seen.
The delay timings were pretty good, but did range from 2 to 2.7 seconds. I am sure more careful measurement of the delay comp would tighten these numbers.
The last lift was quite hard, obviously less BP is actually required, especially once I use the full length of the tubes available. I'll modify the scoops accordingly, the first shot was actually almost perfectly lifted, burning out at apogee. The chlorate star was still moving pretty fast at burn-out. The D1 and TT's were nearly put into orbit! :)
You can hear the MgAl-based Winokur 20 star of the first shot crackling as it burns. I am starting to really like Winokur 20, I am going to design a silver version in the near future.
The hot, over-oxidised burning of the 6:1:1 delay comp did roast the tube a little. You could see in the video how white, bright, and sparkless the candle comp flame was - this is never a good sign if you want cool burning. A proper candle comp would be much cooler and avoid this while offering a better effect between shots. The tube walls could be a little thicker too.
Attachments
| title | type | size |
|---|---|---|
| Candle Video | video/x-msvideo | 5.510 Mbytes |
| Pre-Test Picture | image/jpeg | 35.991 kbytes |
| Post-Mortem Picture | image/jpeg | 32.560 kbytes |