248 replies to this topic

[Jerronimo]

Thanks for the reply Green flames,

Vaseline will probably slow the fuel down a little bit, but at 2% you will hardly notice.
But it has some advantages:

1:working with it is much easier and cleaner
2:the powder compacts much better
3:it produces a more solid (shiny) fuel grain that won't crack or absorb moisture.

The Bp silver formula is:

Pine charcoal Black powder 100
titanium powder 10
Mg/Al (200 mesh) 10
Al spherical (300 mesh) 20
Dextrin 10

[sasman]

Very Nice jerronimo..Rocket 1 was my fav...also the silver flitter was nice...what formula was that and what mesh size was your aluminium

[Jerronimo]

Hey Sas,

Yes I liked the silver flitter also very bright silver, to bad the break was pathetic and I didn't get 100% star ignition.
These stars are probably to big for a 3'' shell, in a 4'' they will look and ignite better I think.

The formula is from Mike Swisher:

Potassium Chlorate 12
Aluminum, flake, bright. -325 mesh, 36 micron 5
Potassium Nitrate 2
Aluminum, flake, flitters, medium 16-326 mesh 2
Dextrin 2
Red Gum 1

See rec.pyrotechnics for more information.

This is the exact Al I used:
Al flitter 1
Al flitter 2

[BrightStar]

Here we go again... Conkling Blue this time.



I saw some great rockets in the sky driving home tonight. Can't wait to test this one

Edited by BrightStar, 31 October 2007 - 10:23 PM.

[dr thrust]

nice pasteing! when she "flying", i tried a couple 3 lb,ers they were seven inch long core burners, the core was 5 inch long with a half inch delay, last night (my first) useing the same 65,25,10 vaseline riced rp,as my 1 lb,ers, i upped the vaseline to 4% and they went up very fast and a good height,but they delay was a "long" three seconds ,should i make the delay comp faster so it gives a extra bit of thrust like a end burner, chris

[BrightStar]

Tested the above rocket this evening to kick off a small show. It's filmed here from about 100m away:

1lb Blue Peony Rocket Test (Divx avi, 2,259 KB)

I was fairly happy with this - it was dramatic enough and the altitude was very impressive. I really need to invest in a star plate for these smaller stars - they were just quickly rough cut to about 7mm and very uneven. Also a 'pokka' configuration would have given a fuller break. The passfire this time was shogun visco passed from the header though a hole in the top clay bulkhead and set about 5mm into the glitter delay grain.

One nice thing about home made rockets is you can make them coast for quite a bit before the burst. It gives a much longer flight and the shop bought ones don't often seem to do this.

Chris, not sure I can help with your delay as it seems to vary greatly depending on the construction and flight characteristics of each rocket. I think you have to just 'dial it in' yourself, but if I were you I would stick to the same composition each time and just vary the depth used...

Edited by BrightStar, 05 November 2007 - 12:20 AM.

[marble]

Had 2 rockets fail on me tonight:

This one was a 1lb made with my new swanky pyrotooling, fuel was some crap i had laying around that was fairly slow. Any ideas what went wrong? This one had a 50g dummy header. Was not happy with the nozzle (was crumbly and and a bit thick) and it crumpled the tube a bit.



Looks to me like a blowout

This one was made with my Chinese tooling (with the nozzle drilled out), tube recovered intact and is perfect, nozzle held out well. Was 1lb with no header. Same fuel as above.

Edited by marble, 08 November 2007 - 01:37 PM.

[dr thrust]

yeah looks like a top plug blow out, did you use the same material as the nozzle? if so what did you use? the second one "slow fuel"with a small core?,what are the dims of your rocket tooling?, ho one more point! dont just use any old "crap" youve got laying around,label it, with milling times and the composition so you know what your using!. be methodical and you'll get consistent rockets. ive put an electric timer on my ball mill so each "batch" gets the same amount of time

[BrightStar]

It's worthwhile just ramming a nozzle and removing it from the spindle to judge whether your clay mix is working as expected. It shouldn't crumble at all and should be perfectly smooth and rock hard. Adding 5 to 10% graphite does seem help it come off the spindle without cracking. For the top bulkhead I just use raw powdered bentonite as it is easy to hand drill for the passfire.

Try raming your fuel hard and in small increments - no larger than 1.5 teaspoons at a time. When you take the motor off the spindle, a few specs of BP will fall out. If you tap it on a hard surface and more falls out you have a cracked or insufficiently packed grain. If it falls out with a second and third tap you will almost certainly be heading for a CATO.

BTW, the remainder of my rocket came down like an arrow and embedded itself a good 3" into the ground The tube (stick still attached) and nozzle were still in place, as was the top bulkhead. The ball shell header was nowhere to be seen.

Beware - these rockets come back down very fast, even when all goes according to plan...

Edited by BrightStar, 09 November 2007 - 08:12 PM.

[marble]

nozzle was shit, i used bentonite pellets which didn't compress like i had hoped

Ive since made a new batch of 60/30/10 ballmilled for 15 mins (I love the timer on my mill) and rammed a new rocket. I used just powdered bentonite and the nozzle looks like it should - nice, hard and non crumbly.

Edited by marble, 10 November 2007 - 12:39 AM.

[dr thrust]

good luck with the next rocket! keep us posted, a good "tip" i use is to mark/put a piece of tape on the rammer when i get to the top of my spindle so i know how thick the delay and then the endplug is on a postmortem of one of my 1lb rockets i found my endplug was only 9mm! its hard to judge the "true" thickness after ramming/pressing

[marble]

Ive written down on a sheet of paper how many spoons of clay = correct nozzle size. Ive got one ready to fly now, stick is a bit short but hopefully it will work.

Ill fire it tonight if it doesn't rain

[marble]

Another CATO, this time it was the whole shebang. Didn't get it on video as the fooking battery ran out when I switched it on but none the less. I'm fairly sure what went wrong, with the 60/30/10 fuel I was out of various mesh charcoal so I just used hardwood aifloat hoping it would be slow enough. Either that or the tubes...

Easy fix I hope, wont be able to fire up my cooker for a while though

Edited by marble, 10 November 2007 - 02:23 PM.

[Anders Greenman]

I've made several end burners lately and they perform well. My 7/8" I.D's can lift a payload of 60g very easily and they are very reliable.
The only thing I'm missing is the sound wich commercial end burners put out. I bought a rocket last year, spanish thing called "Big" (the blue one, on the left). The sound when it took of was amazing! A deep bass and very loud, but the thrust was weak compared to mine wich are of about the same size (7/8"). So, the sound isn't really proportional to force here, it seems. Anyone knows what creates that wonderful loud, deep bass? It musth be something other than nozzle diameter, maybe nozzle length?

Two comerades. The one in front is a hybrid, 6mm nozzle and 1,5 cm core. The other one (grey) is a true end burner with 5mm nozzle and no core.

Edited by Anders Greenman, 30 November 2007 - 11:22 PM.

[dr thrust]

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.