Sciencemadness Discussion Board

Rockets-I have problems.

kecskesajt - 15-1-2015 at 08:43

Yeah.My rockets won't work :(.I make a tube,ram BP into it,drill half way,ballance,put a fuse.It is nossleless. I light it and it makes a bang because it shoots out the clay plug :mad: Can somebody help ?

greenlight - 15-1-2015 at 09:14

Are you using a spindle and drifts to form a hollow cored motor or are you trying to make end-burning rockets?

Are you ramming the black powder in in small increments to get a uniform density through the entire rocket tube? If there are parts that aren't as compact as other parts of the motor it could cause a faster burn rate in a spot which could cause it to shoot out the plug.

You say that your rockets are nozzleless, I'm pretty sure just about all black powder rockets need a clay nozzle rammed to generate the thrust to lift off.

Here are two links for black powder rocket construction which may help you compare your design, one on end burners and one on cored motors:

http://www.skylighter.com/fireworks/how-to-make/End-Burner-R...
http://www.skylighter.com/fireworks/how-to-make/4-ounce-blac...


[Edited on 15-1-2015 by greenlight]

Bert - 15-1-2015 at 13:31

There are nozzleless black powder rockets made- simple, not as efficient as could be with well designed nozzle, but very easy and made without many tools.

Skylighter- Nozzleless BP rockets

I agree with greenlight-
Quote:

If there are parts that aren't as compact as other parts of the motor it could cause a faster burn rate in a spot which could cause it to shoot out the plug.


Can you measure and report density of pressed fuel grain.

How did you make the fuel.

How exactly do you press or ram fuel, what size is a finished loading increment- It should not be taller than the tube ID, or you can't press or ram it uniformly in my experience.


If it's not poor pressing: Either your core is too big, you are not putting the forward bulkhead in well enough, or your black powder is just too fast.

Hawkguy - 15-1-2015 at 16:01

If the nozzle isn't stable enough/ well applied, you'll have an endless range of problems. That was always my biggest problem.

Oscilllator - 15-1-2015 at 16:59

This should solve your problem:
http://www.jacobsrocketry.com/aer/casings_nozzles_headers.ht... and Headers


I especially like the last one with the pvc ring, because it holds the nozzle in place without introducing any bits that stick out from the body of the engine.

kecskesajt - 15-1-2015 at 21:34

Test for my BP: https://m.youtube.com/watch?v=5PGDLqcVvG4 I ram the BP in small amount.I only use paper casing for rockets.I will buy some gypsum to make a better and cap.I using a drill to drill my rocket motor.Anyways thanks a lot 4 help :D

kecskesajt - 15-1-2015 at 21:42

Quote: Originally posted by Bert  
There are nozzleless black powder rockets made- simple, not as efficient as could be with well designed nozzle, but very easy and made without many tools.

Skylighter- Nozzleless BP rockets

I agree with greenlight-

Quote:

If there are parts that aren't as compact as other parts of the motor it could cause a faster burn rate in a spot which could cause it to shoot out the plug.


Can you measure and report density of pressed fuel grain.

How did you make the fuel.

How exactly do you press or ram fuel, what size is a finished loading increment- It should not be taller than the tube ID, or you can't press or ram it uniformly in my experience.


If it's not poor pressing: Either your core is too big, you are not putting the forward bulkhead in well enough, or your black powder is just too fast.
I make My fuel with a coffe grinder.I grind the KNO3 then the charcoal and mix it with the sulfur(75:15:12) And granulating it.