94 replies to this topic

[Mumbles]

This is from Mike Swisher on rec.pyro.

"For black powder rockets, let the case length be 10 times its inside diameter. Let the spindle's over-all length be 8 times the case i.d.; of this, the base which supports the case should be one case i.d. tall, and the tapering portion of the spindle should be 7 times the case i.d. Let the spindle taper from 1/2 the case i.d. at base to 1/4 the case i.d. at its tip, and the tip should be domed with a radius of 1/8 the case i.d. Enough room is provided in the case for a massif, or solid increment of composition, having 1 to 1-1/2 times the case i.d., to be rammed above the spindle, which will normally be sufficient. These dimensions should do for standard American rocket sizes from 4-oz. to 4-lb. "

So for a 1lb rocket:

5.25" spindle length
3/4" base height
3/8" nozzle start diameter
Tapered to 3/16" diameter at top domed with a radius of 3/32"(probably not really neccesary to have this part perfect, just round the top off)

Edited by Mumbles, 25 May 2006 - 09:18 PM.

[Pieman]

Can you give me the dimensions for the drifts as well please? Is it possible to make these on a lathe and just drill the center to the correct depth?

[Spudgun]

I'm really interested in buying the pyrotooling 1/2" bp tool set, however I'm wondering of I could use these tools with a KNO3 based propellant? EDIT: By 'KNO3 based' I don't mean BP, although I would use it for BP rockets as well...

Edited by Spudgun, 23 December 2006 - 09:32 PM.

[karlfoxman]

What mixture you going to be using?

[Spudgun]

Subtle variations on the 60:30:10 KNO3:Sugar:Sulphur mix

[parabolic]

Ive recently turned myself an end burning type rocket tooling set,
I used nylon for all parts, I think they work very well indeed, nylon is very strong, and doesnt get deformed like steel does, it seems to bounce back to shape, the material is non-sparking, and if there is any worry about static then simply earth your self and the tooling against a common ground before using them. as should be done will all tooling anyway


http://www.parabolic...uk/dscn3716.jpg

[maxman]

Looks good! How long is the spindle? and what diameter tubes are you using? Straight meal fuel?

[parabolic]

Looks good! How long is the spindle? and what diameter tubes are you using? Straight meal fuel?

the spindle is 10mm long 5mm od at the tip and tapers up to 6mm at the base, - the taper is just there to make it easer to remove from the rammed nozzle. the tubes iam using have an ID of 20.5mm and are about 3 inches long

I fill the tubes with about a teaspoon of ground cat litter and ram it good and hard with drift no 1, then the rest with straight meal
Drift no 1 has a 10mm deep hole to alow for the little bit of spindle nose that sticks through the rammed nozzle and is also used to ram the first 15mm of BP, then I change to the next drift to ram the rest of BP in increments and then the end plug

I might in the 'new year' make a few for sale on ebay for different tube sizes

[maxman]

So its a true end burner then? no propellant core at all? I have just made one from a stinger spindle cut down from 35mm to 20mm giving 10mm into the propellant. The tubes are 3/4" id and 3 1/2" long. I charged the tubes with 23g meal. I think It wont be possible to make the length greater without improving the nozzle to stop it eroding. I used a 2 1/2" ball shell payload with 22 3/8" red stars and a BP break that weighed 60g It lifted it ok but another I made identical with green stars started to come down and broke a bit low. What will yours lift?

[parabolic]

I havent tried a payload yet, ive only just started in the rockect area of pyro, so iam concentrating on the engines first for a while.

[maxman]

Have you any vids? I'm not sure no core at all will work very well. As I said my core is now 10mm into the meal but using a full size stinger spindle 25mm into the meal usually gets a cato though some fly ridiculously too fast. I think about 15mm into the meal should be just about right. What does anyone else use?

[parabolic]

no vids but the rockets Ive made so far were using a crappy BP which was quite slow, but it still flew very well.
I dont think your right about end burning rockets not working very well,, ESTES the pro rocket engine makers are of the end burning type..
I think its more to do with the propellent that determines the decision whether to use end burner or core type

[spanner]

ESTES the pro rocket engine makers are of the end burning type..

Not all of them. If you look closely, you will note a core extending beyond the clay nozzle, at least on some of the smaller motors, IIRC.

But this was in 1992, they may well have changed the design since then...

Edited by spanner, 11 January 2007 - 03:55 PM.

[xplosive]

Not all of them. If you look closely, you will note a core extending beyond the clay nozzle, at least on some of the smaller motors, IIRC.

But this was in 1992, they may well have changed the design since then...

Try this links , the prices are reasonable.
http://www.freewebs.com/supremepyro/

[karlfoxman]

This is already in another thred.