5 replies to this topic

[nickpatts]

Hi, I have decided to start making my own spindle on my lathe. Before I get started I thought I?d ask here for any advice you can give me or known working sizes, measurements ect. I currently looking at around using a 12mm Id tube. Can anyone give me an idea of the ideal core size,3/4mm? and length?

Thanks in advance

Nick

[Pyromaster2003]

my spindle is 50mm long and 4mm diametre, works great. I think the 3mm diametre one i had before made the rocket shoot up quickter and to a bigger height but this newer one does the job just fine and hasnt made a rocket which has blown up or failed to take off yet.

[Yugen-biki]

I made my first spindle from a screw filed down using a power drill and a file .
I still use a screw but not the same one, and this one is made in a lathe. The spindle is slightly cone shaped make it easyer pulling the rocket off when finished. The spindle is 3mm i diameter at the tip. 3mm will work for most rockets. The most important component is the fuel. I us 66:23:9 BP for my rockets using a plastic tude. You can find more info on:
http://huizen.dds.nl...er/indexEN.html under E6 Rockets

[Matt]

For my spindle:

spindle

I turned up a base (thats my 9.5mm spindle) and Its not got all the angles anymore either, just a ~30 degree slope now, nice and faint same as my 12mm spindle. Now that ive been incoherent for a lil bit. Basicaly make a base to make whatever fancy or plain nozzles you desire, and drill a hole .5 of a mm less than the pin youll use then get some brasing rod for oxy welding. Grab some of whatever diam you want and cut a length of it for how long you want the pin and turn one end of it down a smidge (just hold a file onto it whilst its spinning) then jam it into the hole!

That has nothing to do with measurements but it will sure as hell save you some time turnig a pin. Doesnt need a taper so long as your using BP type propellants. My recomendations for length would be 4cm by 3.5mm, that works great for my chrysanthemum 6 propellant rockets, these have good lift power. I also have a 12mm spindle with a 15mm long 3.5mm pin, this makess *weak* rockets which just keep going and going and going.

Ofcourse the beuty about this kind of pin is that if it dont work just rip it out and put a diff size pin in. Personaly i dont think you can get a straight answer on this as there are way too many variables.

-Matt

[Yugen-biki]

Matt
Personaly i dont think you can get a straight answer on this as there are way too many variables.

Yes there is no universal blueprint for rocket making. The only way is to make rockets and try and try untill they fly!
I use a 17mm clay nozzle (cly --> dry milled kitty litter), 32mm long spindle 3mm in diameter, 50mm BP (the spindle goes in about 15mm in the BP and the nozzle 17 mm) and on the top U may use clay again to prevent the rocket to lose its preasure the wrong way. I use sugar and kno3 instead of clay on the top, and it gives a rock hard dely! (I use a 2ton hydralic press)

[alany]

The general starting point for core-burners is:

Case Length: 10 x ID
Nozzle throat: 1/3 x ID
Cavity length: 7 x ID

That seems to work well with added charcoal BP varients and greenmix. If it explodes, add more charcoal and/or shorten the core. Increasing the nozzle throat can be tried, but it generally hurts the performance. I tune end-burners more with the throat diameter than core-burners.

Making a fully de Laval style nozzle profile is probably not that important for smaller BP rockets.

Honestly I tend to charge the case then drill-out the nozzle and core of my rockets, especially experimental ones. Once I find a good design I may make a spindle up, but for smaller IDs I find a spindle is a big pain to work with, at 19mm and above it becomes OK.