Delay timers in sugar rockets

[mahoo91]

Since i started university i have had a firm interest in the hobby we all share. Recently iv delved into the realm of rockets, had some success with sugar and potassium nitrate as a fuel, iv played around with some simple things like adding smoke dye and getting coloured smoke trails etc but would really like a flash and report. Experimented first with a little black powder encased in plastic film canisters. I used bentonite as a barrier between the propellant and charge with Chinese time fuse as my delay. My problem seemed always to be that the propellant would burn too hot and ignite my charge prematurely and cause lumps of burning rocket candy to fall. Iv had success making other fireworks (fountains Roman candles cakes etc) and the delay has even been ok in my experiments with mortars. My eventual intention is to move on to flash powder as the head of the rocket but obviously will not attempt this without success with lower yield charges. Im a chemistry graduate so know about the inherent danger with FP. Any ideas people? My old lecturer suggested a longer delay, but i don't want to risk turning a fireworks into an unguided missile!

[val77]

mhmmm ramming your rcandy fuel and take black powder for your delay Edited October 27, 2012 by val77

[mahoo91]

Would using black powder not have the same problem? Since that's being used as my charge. Also i have always heated my rcandy to a paste and set it to solid before use, could that be the problem that its burning too efficiently?

[val77]

for this to work

rcandy must be powder (uncooked)

Edited October 27, 2012 by val77

[mahoo91]

Thanks will try this out ASAP. Any advice on sugars to use for best results? As i mentioned im a chemist so have access to more complex sugars or would simple sugars work better? I understand obviously that complex sugar will burn slower for longer and simple sugars will burn fast with a lot of thrust but was wondering if you had any suggestions.

[val77]

simple sugar is perfect !

[mahoo91]

Sorry for all what May seem like arbitrary questions but can you offer any advice on nozel diameter? As i said im new to rockets and appreciate the advice of more experienced people.

[val77]

he depend to the diameter of your tube

[californiapyro]

1/4 the tube diameter for endburners is fairly standard, 1/2 the ID for coreburners. What are your core dimensions?

[val77]

californiapyro for the rcandy fuel the diameter of the noozle depend to the power of the fuel

for a good rcandy test a 1/3 noozle to the diameter of the tube

Edited October 27, 2012 by val77

[mahoo91]

Dimensions i use are around 23mm in diameter by 100mm in length. Using bentonite as my ends with a hole.drilled into it and 3mm visco fuse inserted.

[val77]

drill a 8mm hole for the noozle bentonite is perfect !

[mahoo91]

Thanks alot for the advice guys. Will try asap and probably ask for more

[val77]

a little diagram to help you test and my 5 grams of uncooked rcandy

 

http://i47.servimg.com/u/f47/16/97/86/45/rcandy10.jpg

 

 

and the video

[dailymotion]http://www.dailymotion.com/video/xunwvi_rocket-candy-test-1_webcam[/dailymotion]

Edited October 28, 2012 by val77

[mahoo91]

Thanks for the help. Had a few successful tests and even a couple with FP charges all went well except one hangfire from a broken fuse but i can live with that. Next up bigger rockets and maybe add some stars

[mahoo91]

Another note to thank you guys for the advice. Made bonfire night much better my village fete let me include a few with the usual mortars and i my sugar rockets with 5g of FP and a handful of parlon stars and some falling fuses where much more impressive than store bought. Even had some smoke dye for the fuel to add to the visuals. Couldnt have done it without your help and advice