248 replies to this topic

[icarus]

if you look on vk2zay,s website his rp rocket propellant seems to be less pressure dependant than bp ive had excellent results with it for a none eco friendly cheap case use plastic 22mm water piping to set a bentonite plug into it smear sticky glue around inside end of pipe then dip pipe into coarse dry sand or grit now you have a grit ring round the inside of the tube ram your bentonite plug dont bother waiting for glue to dry its only purpose was to hold grit in place as you ram the plug the grit is impacted into the tube wall locking the bentonite plug into place if you have to drill the plug theres no sand or grit mixed in to make it difficult to drill i use 3mm hole

[Anders Greenman]

could it be the position of the nozzle in the tube, i took a small endburner apart (in the name of science ) and apart from finding it was in a thick plastic tube covered in paper, there was also no end plug! the nozzle was about 18mm up inside the tube.

I've noticed that too. I mean, at least half the tube is just air and clay! And the fuel seems to be pretty slow compared to BP. I guess it varies from motor to motor. The nozzle lenght might contribute to sound due to the increased friction from gases running down the nozzle. And the plastic tube is very thick indeed!
But the nozzle opening is not very small and so the only reason for such a wall thickness must be the lenght of the nozzle.

if you look on vk2zay,s website his rp rocket propellant seems to be less pressure dependant than bp ive had excellent results with it for a none eco friendly cheap case use plastic 22mm water piping to set a bentonite plug into it smear sticky glue around inside end of pipe then dip pipe into coarse dry sand or grit now you have a grit ring round the inside of the tube ram your bentonite plug dont bother waiting for glue to dry its only purpose was to hold grit in place as you ram the plug the grit is impacted into the tube wall locking the bentonite plug into place if you have to drill the plug theres no sand or grit mixed in to make it difficult to drill i use 3mm hole

I add about 25% rough blasting sand to my clay and cut riflings inside the tube. I also press the first increment without tube support (plastic tubes), so it expands and makes it almost impossible for the nozzle to blow out.

[Jerronimo]

http://www.pyrobin.com/files/fuse.jpg
http://www.pyrobin.c.../nozzleless.jpg
http://www.pyrobin.c...ozzleless 2.jpg
http://www.pyrobin.c...lash salute.jpg

A couple of rockets I build today .
1 pound nozzle-less with 4'' header containing slow gold to red stars and 6 20mm crackling comets, 6 gram whistle booster.
1 pound nozzle-less with 3'' header containing pressed tiger-tail stars, 3 gram whistle booster.
1 pound nozzle-less salute rocket containing 10 grams of nitrate flash.

Rocket fuel is 3 hour willow meal + 2% vaseline.
4'' shell weight 360 gram
3'' shell weight 140 gram
Both are plastic shells pasted with 4 layers of gummed paper tape.

Will probably shoot them tonight or tomorrow, will post vid's if I succeed catching them on film.

EDIT:

rocketvideo here's the video of the rockets I fired.

The nitrate flash salute was awesome really loud nice deep boom.
The 3'' tigertail shell rocket didn't reach a high enough altitude, but the break was nice.
The 4'' shell went high enough but didn't break properly, I think I jammed to much stuff in there, the 20mm comets take up lots of space leaving little room for burstcharge.
Also the red cores didn't ignite but the slow gold stars look realy nice, could have broken it a bit harder I think.
Next time I will try 8 grams of whistle and just some small pistil stars mixed in with the burst.

Edited by Jerronimo, 03 December 2007 - 07:01 PM.

[dr thrust]

nice! the motors went well, seeing they had no nozzles, ive never seen that on a bp motor before where did you get the idea? is it somthing you normally do or just trying new things?

[Anders Greenman]

Some very nice rockets there man! Very good filming too!

[pudi.dk]

Woops!

[dr thrust]

woops indeed! ho well at least your stars lit, ia'm having prob's with my passfire's somtimes they work somtimes not! they are usually to the side of the top plug and 3-3.5 mm wide in a 18mm coreburner how big can i go? 5mm? and would two passfire's work? one each side of the end plug?how do you do yours?

Edited by chris m, 17 December 2007 - 09:06 PM.

[Jerronimo]

Well, I also (had) problems with my passfire's.
It really sucks when a nice 4'' ballshell heading fails to light and falls back to earth .
The nozzleless rockets I make should not need a clay bulkhead as the pressure inside the rocket is not as high as in a normal nozzled rocket.
But I haven't tested any rockets without one and ram some clay on top just to be on the safe side.

It's hard to tell if the rocket passfire is the problem or the internal fuse of the ballshell fails to catch fire.
On my last launch I drilled a 6mm hole in the bulkhead, put some lose blackpowder on it and made sure the internal shell fuse didn't fit to tightly inside the tube I use to pass fire to the middle of the shell.
It worked perfectly so I hope this method will have solved the problem.

[dr thrust]

hmm,6mm! thanks i will give it a go

[dr thrust]

heres a question that's "been rolling around in my head for a while" it regards big rockets. like 3lb, 4lb, 6 lb, the thing is, that most of the rocket motors ive seen on the net and here on this fine forum, are usually about seven to eight inch's long.

every things fine i here you say! and indeed my 3lb'ers work a treat but when you dig deep into some of the "old time books" they quote 3lb motor being ten inch long and 4 lber's 14 inch and 6lb'er 16 inch!! has anybody made a motor that long!!

what would the benefits be more thrust?, longer burn time? and would it affect the timing of the delay or not? hmm so many questions ps in brocks book he say's that a 6lb rocket body should be twenty inches long!and other books talk of 14ft long sticks that's got to be some f+@king rocket!

Edited by chris m, 27 December 2007 - 11:35 PM.

[Mumbles]

The most common length for black powder rockets is 10x the ID generally. So a 6lb rocket would be 15" by this measurement, but 16" is more common for some reason. I've never made any this big but have seen numerous ones in person.

Edited by Mumbles, 28 December 2007 - 04:50 AM.

[Skarphedin]

I made a few 4oz rockets for new years eve. This is the best one:

http://pyrotechnics....l_ballshell.avi

Also on YouTube:

I use passfire 4oz bp rocket fuel. Ignition with quickmatch and a bit of visco fuse in the end.
The header is a 1.75" ball shell with 3/8" pumped tiger tail stars, bp on grass seeds and 0.3 gram slow nitrate flash for break. Hemispheres made of newspaper and pasted with 6 layers of thin recycled kraftpaper.

I have a few areas I want to improve: a slightly harder break and a slower burning delay above the core of the rocket. Now I have only used rocket fuel, but I want to try a slower burning composition to get a small delay before the shell bursts.

Do you have any other suggestions for improvement?

Edited by Skarphedin, 05 January 2008 - 02:11 PM.

[digger]

Here is a video of a few of the rockets I made for Nov 5th last year. The headers were my first attempt at 3" ball shells (2 3/4 plastic). The stars were veline, however the colours don't come out very well on the video (they were not as good as they could have been anyway due using PVC instead of Parlon).

So what do you think to my first attempt.

A Few Rockets

P.S. I know there were a few blind stars, however that was due to lazy priming and vacuum drying

Edited by digger, 09 January 2008 - 10:18 PM.

[dr thrust]

ho! so many rockets great first attempt, well timed bursts, looks like ever body on the video enjoyed them! just being nosy.. what was the comp you used in your motors? i just like trying different comps until i find a really good one!

[digger]

ho! so many rockets great first attempt, well timed bursts, looks like ever body on the video enjoyed them! just being nosy.. what was the comp you used in your motors? i just like trying different comps until i find a really good one!

Thanks (That was only around 1/3rd of the volley of six banks of 8 rockets, the misses taped over the rest)

Pretty basic comp

KNO3 75
Norit Activated Carbon 15
Sulphur 10
Titanium Sponge +5%

All but the titanium milled for 4 hours then titanium mixed in, then pressed into the casings. This is for quite a short core motor, so it would probably need a bit more carbon with 1lb, 3lb etc tooling.

Just as an example in the first picture below of some of my home made tooling (I make all my rammers and cores from alubronze) the tooling on the left was used for these rockets, the middle tooling is my 1lb tooling and the right hand side tooling is 3lb tooling. The ID of these rockets is between that of the 1lb and the 3lb tooling.