7 replies to this topic

[ridley]

sssssssssssssssss

Edited by ridley, 14 February 2015 - 10:02 PM.

[Arthur Brown]

All the figures are "about right!" However there are lots more to select also.

The dimensions are important, then the compound ratio is important, then the particle size and mixing is important. Also all of these are interdependent!

[ridley]

All the figures are "about right!" However there are lots more to select also.

The dimensions are important, then the compound ratio is important, then the particle size and mixing is important. Also all of these are interdependent!

I have been using 60:15:10 and then adding a further 15 as charcoal powder for added tail. Today the one drilled at 4mm CATOed, blew out the end plug.

Ridley

[digger]

I have been using 60:15:10 and then adding a further 15 as charcoal powder for added tail. Today the one drilled at 4mm CATOed, blew out the end plug.

Ridley

The questions are. What are you using for your end plugs? are they at the very end of the tube or set in? how are you consolidating the the motors? How thick are the end plugs?

Edited by digger, 12 January 2008 - 09:08 PM.

[ridley]

Iam using bentonite rammed to about 12mm set into the end by 5-8mm.

To be honest all but the latest of my CATOs have been when the tube burst, i got them from inoxia.

Ridley

[ridley]

I always thought the spindle should go quite a long way up into the composition, a 4cm spindle would only go 3cm into the composition. Or is my drilling so far into the composition what is causing the catos with the small nozzle size?


In the forums I have read.

"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. "

That seems a lot different from the one proposed by supremepyro. So which is "right"

Ridley

[W.P]

Neither, there aren't definite dimensions and guides to follow for the hobbyist because of the many influential factors. I had a lot of blown end plugs (using bentonite clay) so I increased my nozzle size to double to compensate for the weak plugs.

[ridley]

If I doubled the thickness of my endplug to 2cm say the the spindle would only go 2cm into the composition, would this be enough?

Ridley