Marco Posted November 5 Posted November 5 I want to make some tooling for 3/4" and 1" BP rockets, I have a lathe and various metal stock but i need some dimensions, especially the nozzle diameter as too small and Bang, or too large and poor thrust. Any info would be greatly appreciated.
Arthur Posted November 5 Posted November 5 The other half of the equation is "what powder mix will you use?" A fast powder will make much lift but need a big nozzle, maybe even no clay at all. A slow mix will need more restriction in the nozzle but make less thrust but for longer. Fast BP is usually too fast, but may fly nozzleless. A mix of meal and stir mixed ingredients will be slower but need a nozzle. ALSO big rockets may need a slower powder than works wll in a small rocket.
DavidF Posted November 6 Posted November 6 (edited) From Hardt's 'Pyrotechnics'. It's worth noting that if the 'A' dimension is not increased, a sloppy fit in the tube will result. Some toolmakers use standard 3/4" or 1" rod stock and make sloppy tooling. Others make the tube fit snugly on the spindle base, which is much better. 3/4" and 1" NEPT tube IDs are about .015" over-sized from nominal. Edited November 6 by DavidF
Marco Posted November 6 Author Posted November 6 Firstly thank you for taking the time to reply yo my post and with axactly the info I hoped for DAVIDF. I live in a small town in South East Spain and have always dabbled in fireworks, Both in the UK where I am from and since l have live here. My preferences has been for morters in the past but some of my neighbours have dogs that are not amused by the sound of the lift charge, so now that i have retired I decided to get into rockets (less noise going up and more height for the bang). ARTHUR, a very good point, I love tiger tail & willow bursts so I had planed to incoporate in the fuel something to give me a good. Tail on the way up, I guess this would probable slow down the burning rate but I haven't yet looked into it.
Arthur Posted November 6 Posted November 6 Remember that the tool set needs tubular rammers with depth limit marks. The tapered centre pin needs to be fastened to the base with a bolt threaded into the parallel portion and there should be a washer between the pin and the base, otherwise the centre pin will lock up as you try to pull it out. While a shell has the single bang of the lift charge, a rocket has hundreds of hammer blows as you compact the core material in increments. Otherwise you should use a hydraulic press (still pressing in small increments). Lancaster has mentioned in his book that some rockets are simply pressed full and then a core is drilled out, but this demands tooling to keep the drill straight and centred. The tube never fits the tool perfectly because it's impossible to make a paper tube that doesn't change size slightly with the local weather. Typically a medium size rocket contains 20% meal powder then the rest as meal ingredients in sizes from 10 mesh to 40 mesh in vaguely the usual BP ratios. Bigger charcoal is lost to the lift but shows as the tail, small spherical aluminium or steel can be included in minor amounts to add brightness to the tail
Marco Posted November 14 Author Posted November 14 Hi Arthur, sorry for the delay in replying we've had a series of guests come to visit (a free holiday!), alway nice to see them but nice when you get your life back. Thanks for the info, on the subject of info, I was looking on a long forgotten website only to find coppies of "Pyrotechnics by Alexander Hardt" and "Chemistry of Pyrotechnics-Basic Principles and Theory" in pdf format for free!. Anyhow thanks again until next time marco
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