OblivionFall Posted October 24, 2014 Posted October 24, 2014 (edited) Hi there, I am trying to make some small BP rockets for this Halloween with the few supplies that I have. I have some 5/8" I.D. x 1 1/2" Length x 3/32" Wall spiral tubes that I am going to use for the rockets. I have the long, thin piece of dowel to balance it, a short 5/8" piece of dowel and a heavy metal bar for a mallet and that's what I've been using so far. The process: Take the 5/8" tube and place it on flat piece of wood, proceed to pour a bit of clay into it and ram with dowel and a heavy piece of metal as a mallet.Fill a little bit of black powder from other fireworks that used to be granular but has since been grinded into a powder form, ram with dowel, repeat.When I have rammed the black powder over 3/4 of the way, this is where the problems come in. I tested the rocket perfectly balanced with a piece of dowel. It had no core and it was just a bit of BP rammed into a tube. It burns very fast for a little over a second and lifted the rocket in the air a couple of feet. The problem is, I wanted more thrust so I tried giving it a core and clay end nozzle by ramming it all into the tube then drilling a hole through the middle of it almost all the way into the black powder. When I tested it, it was more of a BP salute than a rocket. I figured the problem was that I had some loose BP in there. I tried it again, but only drilled to the end of the clay, giving it a clay nozzle but no hole through the black powder. I illustrated what I did here: http://i.imgur.com/e79bai1.png Pretty much what I'm asking here is if I have the right idea making these rockets. I don't have much time to make these and test them and I want to conserve the materials I have left for Halloween. Please provide me some constructive criticism/tips/methods of making these. Edited October 24, 2014 by OblivionFall
stix Posted October 24, 2014 Posted October 24, 2014 (edited) I'm pretty new to bp rockets myself and I'm sure others will be able to point you in the right direction, but . . . Fill a little bit of black powder from other fireworks that used to be granular but has since been grinded into a powder form . . . How do you know that it's straight black powder without some unknown additive? Also, how big is the nozzle hole you are drilling? Just a thought. Edited October 24, 2014 by stix
Col Posted October 24, 2014 Posted October 24, 2014 (edited) Repurposing unknown comps is a dodgy business, best avoided imho. Granulated sounds like it may have been lift originally. What did it come from? The test results suggest its not hot enough for the endburner (or nozzle too big) and too hot for the core burner (or nozzle too small, core too long. The 5/8" id x 1.5" tube doesnt really have enough length for a coreburner, a short fat endburner may work if you reduce the nozzle size but its not ideal. It`d be easier to roll a new tube thats more suited to the job. Edited October 24, 2014 by Col
BurritoBandito Posted October 24, 2014 Posted October 24, 2014 I agree with Col about the fuel being too hot for a core burner, they typically use a cooler 6:3:1 BP. Try toning it down by adding a bit more charcoal. Also aside from the length of the tubes they are spiral wound, but you should be using convolute tubes. It really would benefit you to just roll your own. Metal isn't really ideal for ramming either. You didn't specify if you hand drilled the core, so I'm just going to put this out there do NOT use a powered drill for making cores!!!
OblivionFall Posted October 24, 2014 Author Posted October 24, 2014 Repurposing unknown comps is a dodgy business, best avoided imho. Granulated sounds like it may have been lift originally. What did it come from? The test results suggest its not hot enough for the endburner (or nozzle too big) and too hot for the core burner (or nozzle too small, core too long. The 5/8" id x 1.5" tube doesnt really have enough length for a coreburner, a short fat endburner may work if you reduce the nozzle size but its not ideal. It`d be easier to roll a new tube thats more suited to the job.A while back I was taking the reports out of cakes because I figured it was too dangerous to make them myself and I had some granulated lift BP left over.
OblivionFall Posted October 24, 2014 Author Posted October 24, 2014 I agree with Col about the fuel being too hot for a core burner, they typically use a cooler 6:3:1 BP. Try toning it down by adding a bit more charcoal. Also aside from the length of the tubes they are spiral wound, but you should be using convolute tubes. It really would benefit you to just roll your own. Metal isn't really ideal for ramming either. You didn't specify if you hand drilled the core, so I'm just going to put this out there do NOT use a powered drill for making cores!!!I drilled very slowly through the clay but not into the BP. I used a wood dowel piece to ram and the metal as a mallet.
Blackthumb Posted October 24, 2014 Posted October 24, 2014 I constantly make small BP rockets from salute casings....9/16 x 1 1/2". They are easy and the tooling is low or no cost. Will do a video and post it.....fly about 300-400'
schroedinger Posted October 24, 2014 Posted October 24, 2014 Oblivion one real fact you missed out here is, how big is your exhaust hole?For an endburner it should be between 1/8 and 5/32 with your tube. Try those size and tell us hoe they work then. Also if your powder is fast you are only having about 1" of powder in it, which will result in a thrust phase of just about 1.5 to 2 seconds. That is not much and will give maybe a rising hight of 100' max.
Recommended Posts