59 replies to this topic

[dr thrust]

interesting video, but whats the propellant? 3 inch rocket from what i have read the ideal set up is igniting the top of the core, a handy tip for when i try these i'm going for a fast willow bp 3lb, 8"core

Edited by chris m, 10 June 2008 - 11:03 PM.

[Sambo]

I would say that’s probably an ammonium perchlorate type propellant.

I've made a few nozzle-less rockets i use fast willow bp, 1" id by 6" long case with a 3" core 8mm diameter.
These rockets are super fast, probably capable of lifting a 3" shell.

I tried ramming one on my standard bp core burner tooling (8"core 10" case length) using half an hour milled pine bp (this is slow bp) and it was a huge cato; it split the case down the entire length, these were tubes from pyrotubes4europe so they were very good strong tubes. I would advise against the long core with fast bp, im trying unmilled greenmix next with a long core.

[dr thrust]

hi, sambo thanx for the info on your rockets very interesting! ive got a supply of those tubes and they are very strong indeed and i'm quite surprised to find these can Cato as well as nozzle'd motors this was the main reason i was going to try them to get away from cato's, never mind i still try them with a fast willow bp riced with 3% Vaseline as my other rockets and try pressing instead of ramming, got any video of your 10" motor? i love em!! heres mine 10", with 8" core

[Sambo]

My 10" motors are very similar to yours, they seem to burn on the pad for a few seconds before take-off.
I dont think i've got any vids, ill make a motor now and fire it later on.
Heres the pic of the CATO - pyrobin

[dr thrust]

ha found some info on building them! looks like i wasn't to far out using Vaseline as a binder, on the link page they use oil, which i have tried in the past but found this gives no tail, any way I'm rambling on heres the link

[Sambo]

Heres one of my 6" * 1" ID nozzleless rockets. Nozzle-less rocket
Sorry about the vid, its only filmed from a digi camera not a camcorder. I think it accelerated a bit quickly for my dad to follow it

Total weight was 312g with a 123g dummy header in a 3" ball shell. It seems like it is capable if lifting alot more, i will test one with a 4" ball header and about 250g dummy payload.

Edited by Sambo, 12 June 2008 - 02:36 PM.

[Sambo]

Just made and tested another 3lb nozzleless with 10 minute milled pine BP, yet another CATO.
It looks like i'm going to have to change the ratios about a bit. Heres the post pic of the rocket

Edited by Sambo, 13 June 2008 - 08:02 PM.

[dr thrust]

hooo nasty cato! are you still ramming?, ive just made a few 1"id, 6" long pressed to 3 tons, taking them down to the icarus meet, ill try and film it, chris

Edited by chris m, 18 October 2008 - 01:41 PM.

[Sambo]

yeah, my press is a bit small for the job, i could do with welding a new one up really, got all the bits just never got around to it.
It would be great if you could get some vids, have they got any headers?
Ill keep experimenting, and post any results here.

[dr thrust]

no headers for the motors,just testing the design but i will try them with a plastic bottle of water to see what weight they can lift, if they lift 300g thats a four inch shell! so far ive made two 1"x6", one 1lber, one 3lber, cato chris will earn his name tomorrow

[Sambo]

How do you fuse you'r coreburners? i used to fuse with visco that went about half way up the core but i found the take-off was slow.
I've just tried with one strand of black match all the way up the core as skylighter reccomends, the lift was quick untill it cato'd at about 15ft
It seems like most of the motors i build atm cato.
Whats your 3lb propellent ratios? mine is 51/40/9 kno3/c/s

How did yours go on sat anyway? got any vids?

Edited by Sambo, 15 June 2008 - 04:17 PM.

[dr thrust]

hello! hmm how do i fuse them? so far i just bend the last 10mm over it self and push it up the core about 12-15mm this stops the fuse from falling out, as for a slow take off definitely not! no Cato's today from cato Chris

the propellant was four hour willow meal 75,15,10 riced with 3% Vaseline which was dissolved in warm cellulose thinners, this is then left to dry for a few days then!! this is the important bit! pressed to two tons

i made three motors first a standard 1lb bp rocket tooling, a six inch long 1"id motor this lifted 260G with ease, and a 10" long motor carrying 360G , its hard to see the rockets after they launch so ill do a night time one with headers, also it looks like you don't need a clay bulkhead heres the vid rocket test

Edited by chris m, 16 June 2008 - 07:39 PM.

[pyrotrev]

An idea for you guys... Whilst playing with star comps I tried binding some with polyester resin thinned with acetone to enable even mixing. Though the stars were admirably hard (think milling media ), the burning rate was pants. Just struck me it might be a way of slowing down over-eager BP for core burners, whilst keeping the best F/O ratio for efficiency. You'd need to get your shit together though as far as pressing went, since once the catalyst is mixed in you've got maybe 20 mins in warm weather before it starts getting too thick to work.

[Sambo]

I've been thinking this for a while, i was thinking of thining it untill it just becomes pourable.
Lube or use a releace agent on the spindle and put a tube on; you simply pour the propellent in and pull a vacuum on the top of the tube to remove any air bubbles trapped.
The F/O ratio would ahve to be changed slightly as the resin would act like another fuel in the mix, i would probably use a 60/40 ratio so every 4 parts resin i would add 6 parts oxidizer.

Edited by Sambo, 17 June 2008 - 02:58 PM.

[dr thrust]

your Right pyrotrev polyester resin is pants! a few other members on this forum have tried it before and had poor results, its looks like the resin of choice would be resorcinol resin also cooperman stocks it, i suspect you would also have to experiment with different oxidizers