Well, the first one flew....

[Dodad]

Hello All,

 

I have been working with a 4 oz BP tooling kit from Wolter. I am using a KNO3 SU fuel.

Here is my first shot.....

 

Humm.... "You aren't permitted to upload this kind of file" MP4?

 

Link:

https://docs.google....t?usp=drive_web

 

Well, anyway the first one was a resounding success! Then it gets to be mixed results. Blowen out end plugs (Bentonite).

I believe the fuel was not rammed enough. The next one flew ok. The biggest problem I seem to be having at the moment is that

the rocket fuel is sticking on the spindle. The last one I used slip joint pliers to twist on the tube. I buggered up the tube enough

that I was worried it would fail. So I wrapped the area with strapping tape. This was for a static test to test a new nozzle mix.

It blew out the end plug with very little burn time. I believe it was rammed enough. I am thinking that I fractured the fuel grain with the pliers.

The question I have is how to keep the sugar fuel from sticking to the spindle. I am guessing that this is less of a problem

when using BP.

Edited September 7, 2013 by Dodad

[leedrill]

hi dodad go buy some graphite powder from somewhere always coat your spindle in it before pressing will solve all your problems if you coat well enough and between each motor i can release a 190mm spindle from a 3lb motor by hand when the bp is pressed to 7500psi from the second increment up so that might give you an idea of the difference it makes graphite powder gets used in industrial applications very similar to this and it is basically pure carbon

 

 

if you do need to use pliers again place a rammer inside the tube and grab onto the bit of tube ssupported by the rammer you might of done this but just thought id add it

Edited September 8, 2013 by leedrill

[Dodad]

Thanks Leedrill, I have tried a few things. Liquid Rollers, (a silicone spray). I think a large part of the problem is the sugar propellant. It really sticks to the spindle

and the aluminum rammer ends. When i used the pliers the motor was complete so the only place the rammer could go would be the last 1/2" of the tube.

[leedrill]

well yeah use the last half " of the tube to do it will be better than applying pressure to the grain and silicone spay is a good lubricant but would not work for that application well it would help but seriously post back here after you have tried the graphite powder and im sure your response will be positive

i worked in stressing anchors and the strand anchors use a conical wedge system to hold load with a tapered cone in a block head the strands receive up to 25ton each.

if the blocks are new and the wedges are clean most of the time you have no chance of getting the wedges out with a 15lb sledge hammer but if using graphite powder you can usually get them out by hand or with a slight tap from a carpenters hammer

[Dodad]

I will give it a try. I wonder if the fuel increments will wipe the graphite off leaving the remaining exposed spindle uncoated. That sugar fuel really does stick. It leaves rings of the stuff on the spindle that is difficult to clean off.

Some kind of nonstick (paint) coating would be nice.

[Dodad]

I polished the spindle with metal polish. Then I rubbed it with wax. This did the trick! The motor popped off easily and cleanly. I did a static burn and all went well except my nozzle eroded quite a bit.

I am working on a Bentonite / Graphite / Parafin mix.

[leedrill]

what is used in place of graphite powder in this sort of thing is graphite spray you can also get ptfe sprays but you are more after a coating which not only lubricates but also creates a soft barrier for easy release im glad to hear that the wax worked well for you and to be honest graphite is quite messy so if your happy with the wax great but graphite would still work better take it you are ramming your motors when using a press bp and kn/su fuels both are hard to release and if i forget to use graphite on my coreburner tooling it is nearly impossible

[Dodad]

I finally made a batch of BP using Skylighter charcoal. I moistened it and made a "potatoe" as per thier instructions. I granulated it.

Its much less dusty than it was. It was screened not milled. The 4 oz rocket flew just fine. I seems louder taking off than KNSU. It is more messy too.

My next step is to make some white pine charcoal. I have a Harbor Freight tumbler I have'nt used yet. I need media of some sort. I have a 6 piece fishing weight mold, 3/4 oz egg weights. I think I can make them without holes. The fun continues........

[leedrill]

fun indeed dodad and im sure you would of gotten even more addicted after seeing a better tail