superspike23 Posted June 28, 2007 Posted June 28, 2007 here video. I not understand what is the problem. I try manydiameter of nozzle and always the same result.http://www.apcforum.net/files/essai10.wmv
aquaman Posted June 28, 2007 Posted June 28, 2007 Can you briefly explain your procedures for making it? Like what fuel you're using. The diameter or size of the rocket. Core or no core. What you're doing for the plug/nozzel. Are you pressing it or ramming it? Just stuff like that.
superspike23 Posted June 28, 2007 Author Posted June 28, 2007 I use simply black powder 75/10/15. the length of the engine is 9 cm. the internal diameter 12mm. the nozzle 3mm. I bore has 2.5 cm in the back powder. I use of Shell of 13 gram.
Jason Posted June 29, 2007 Posted June 29, 2007 I'm not an expert, but it looks like you have a few things wrong: 1) Your rocket is not long enough for the I.D. you're using.2) Your core doesn't seem long enough, either. I would say a 1/2" rocket is normally ~4-5" long, whereas yours are ~3.5" long and almost an inch in diameter. Also, most cores extend further up, how much further exactly I don't know.
moonshot Posted June 29, 2007 Posted June 29, 2007 First slow your powder down by making a 70/25/5 or 60/30/10 mix. Keep your tube ID the same but lengthen it to 10cm. Make your core 4.5 to 5cm long.Keep your nozzle ID 3 to 4mm. Try to use a longer but lighter stick to make the rocket fly straighter. This rocket has these specs.http://s107.photobucket.com/albums/m314/di...=Picture061.flv
psyco_1322 Posted June 29, 2007 Posted June 29, 2007 How do you make your core bigger than the nozzle?
moonshot Posted June 30, 2007 Posted June 30, 2007 The 4.5 to 5cm is the LENGTH of the core. The 3 to 4mm is the INSIDE DIAMETER of the nozzle. I ram my rockets on a SPINDLE that has a LENGTH of 5cm and a 3mm diameter at the base of the spindle taper making the INSIDE DIAMETER of the nozzle 3mm. Is this a simple enough explanation?
Aquarius Posted June 30, 2007 Posted June 30, 2007 Are we talking about end- or coreburners here?A 12 mm coreburner works ok with a 4 to 5 mm nozzle and say 6 to 7 cm core if the fuel is not too hot. As for the 3 mm nozzle, I suspect we are entering the endburners? But a 3 mm endburner with a 12 mm ID should work, IF your BP is hot enough (I newer had any success with endburners so far due to my cool BP).
superspike23 Posted June 30, 2007 Author Posted June 30, 2007 I makes a stopper clay of 1.5cm height. the height of powder black is 6cm. I bore 2cm approximately in the powder. I am between a endburners and a core burners.
Aquarius Posted July 1, 2007 Posted July 1, 2007 A good guide is to make the casing 10 times the ID of your driver, the core 7/10 of the length of the casing and the nozzle 1/4 of the drivers ID. And to read some of the posts on this forum.
cplmac Posted July 2, 2007 Posted July 2, 2007 Cores are generally 1/3 the ID, and there is no need for your clay nozzle to be a quarter of the length of the motor. I'd start by making a clay nozzle no longer than 1cm at most, and make the core itself longer. I use 75/15/10 for my BP rockets too and they fly just fine. Make that core longer and the clay nozzle shorter.
Aquarius Posted July 3, 2007 Posted July 3, 2007 Sorry, my bad. I did not make myself clear. I did not mean that the nozzle should be 1/4 length of the casing and a spelling mistake on the 1/4. My point is as cplmac's, only worse written.The specs listed works well, try it out and tune it in by correcitng the spindle/core length and/or the fuel.
psyco_1322 Posted July 5, 2007 Posted July 5, 2007 The 4.5 to 5cm is the LENGTH of the core. The 3 to 4mm is the INSIDE DIAMETER of the nozzle. I ram my rockets on a SPINDLE that has a LENGTH of 5cm and a 3mm diameter at the base of the spindle taper making the INSIDE DIAMETER of the nozzle 3mm. Is this a simple enough explanation? Oops. Must have missed the long part on your post. Unless you edited that? Ya I get what your taking about now.
frogy Posted August 27, 2007 Posted August 27, 2007 Yes... Is that 75/15/10 ball milled for at least 3 hours? Because the rockets should be flying without any core if your using 75/15/10... If you are actually using green mix (not ball milled) or 6:3:1 you should make a core that is 1/3 of the ID of the motor in diameter and 7/10 of the propellant grain in length... So if your motor is a 1 lb. (3/4" by 7.5") you want to make the core .25" by 4.5" or so...
mormanman Posted August 29, 2007 Posted August 29, 2007 I have found a mix of black powder and I want to know if anyone else has tried it. I have post something about this before but the black powder I discovered was on accident. I was when I was first starting out. The ratio was the regular 75/15/10 but the sulfur and the charcoal are switched. It really does work good for rocket. I only tested it tying it to the ground but the tail was long and orange but had a lot of thrust (so it appeared).
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