248 replies to this topic

[Pyromaster2003]

Tested a couple of rockets tonight...

Been making stars lately so thought id through the 4 iv been working on in a vitiman bottle and put this on top of a end burner i wanted to try. I thought it was decent but only a few of the charcoal/al and blue stars lit and the gold glitter and red ones never. The rocket needs a smaller choke next time, was a 3/4 inch ID tube x 5 inch long but was under powered, the shell only weighed 150g...

The second one was the same size rocket and 80/20 meal/unmilled black powder + 1% FeTi fuel but was only filled half way and the remaining gap was riced bp and a few blue stars for a mine effect, only a few lit again would have been a good effect if it worked properly. Back to the drawing board for these two..

3 inch vitiman bottle shell and rocket test:


Blue star and rocket test:

Edited by Pyromaster2003, 16 May 2007 - 10:01 PM.

[aquarius]

Not too bad if you ask me.
I'm trying out endburners in the same spectre, 15 mm but with a somewhat weaker fuel I suspect, 70:20:10.
What's the size of your choke?

[Pyromaster2003]

Cheers i was pleased with it with me just starting to make shells the next one will be better - every one that fails gives you more knowledge so i learned from it. The choke was 5 mm but with end burners iv had more success using a 3mm choke for a 19mm ID so il try this next time and let you know how it goes. Surprised you use a weaker comp normally end burners require as fast as possible mixes from my experience..

[aquarius]

Yup, I have tried with 3 mm in a 15 mm ID enburner with a bit more fierce BP, and it whent "bang".
The standard 70:20:10 is a good measure for my coreburners, and give a good tail without any metals.

I'm thinking about a faster powder and 4 mm for my 15 mm ID endburner, since I have a hard time getting these buggers right.
And I hate ten comps for ten drivers.
Therefore the "standard" comp of 70:20:10, is't fast and it's easy, and I tend to manipulate my toolings rather than my comps.
Each to one's own..

[portfire]

Hi all.Just finished two coreburners,one big an one small.

This is the larger one of the two.105mm/15mmID/4.5mm choke.The propellant for this one is 6/3/1 milled for 30mins then i added 10% charcoal to slow it down a little,with it been a coreburner of this size with a small choke.





I had ago at making some tooling for this one,it's abit crude but it seems to have worked


Here is the smaller one


70mm/10mmID/4mm choke.The propellant for this one is 6/3/1 milled for 1hr.


Regards
dean

Edited by portfire, 18 May 2007 - 03:46 PM.

[portfire]

Hi all.Well i'm pleased to say that my rockets are improving.
Here's the 15mmID


10mmID


I drilled the core by hand (it wasn't central and thats why it flew right i think,plus it was windy) in the 10mm one,which i hate and this is the reason i made some tooling for the 15mm,which worked!so i'm going to make some more for 10-12mm rockets.


dean

[Pyromaster2003]

Look like decent rockets, plenty of thrust but that one that you drilled out looked a bit precarious lol! Doesnt matter what the tooling looks like aslong as it does the job and it obviously did the job for the 15mm one. Im going to have to make some tooling for 3/4 inch rockets dont think i will be able to get a really good thrust from an end burning, not good enough to lift a 200g+ shell over 2-300 feet. A couple more end burner tests tonight and then il make some tooling no chance am i drilling the core out...

[portfire]

Look like decent rockets, plenty of thrust but that one that you drilled out looked a bit precarious lol! Doesnt matter what the tooling looks like aslong as it does the job and it obviously did the job for the 15mm one. Im going to have to make some tooling for 3/4 inch rockets dont think i will be able to get a really good thrust from an end burning, not good enough to lift a 200g+ shell over 2-300 feet. A couple more end burner tests tonight and then il make some tooling no chance am i drilling the core out...

Yeah i'm pretty pleased with them,room for improvement though .Although the 10mm one flew right it did have constant thrust and a nice tail,(you cant see it all that well on the vid)the 15mm seemed to chuff,dont think i rammed it hard enough.I'm going to make some 10mm tooling tomorrow so hopfully i will get a better result.

dean

[Pyromaster2003]

Made some end burner tests just now using straight meal no ti or anything else. Guessing the 3/4 inch one the other night with the test shell on top had too large of a choke coz the one iv just lit got just under 1.4Kg (1.375kg) of thrust which is just over 3lbs about right for a 1lb rocket??
The 4 oz (half inch) one got JUST under 400g (399g) which is 14 ounces.

Heres the vid, comments would be appreciated on how good of a thrust i got for these two as im not sure how good/bad it is and how much do you clued up rocket makers reckon each of the rockets could safely lift to a decent height?

Vid ...

[sasman]

I have not made any rockets for a long time .. The only advice i can give is that i made a 3/4 inch diameter rocket and using a old spring balance to measure thrust got well over 5 kg initail thrust.. and about 1 kg constant thrust?..From your video i could not see your peak thrust but it looked low..and your constant thrust was about 500 gr?..

I stopped experiments on my rocket but i will soon start making some more and intend to make em more powerful..20 lbs intail thrust should be possible? according to some experts?..Looking at your 3" Rocket shell you can see they are way underpowered.. Do you have a press? a press should enable you to press harder and therefore use faster fuel..Which should=more thrust?

Edited by sasman, 19 May 2007 - 10:22 PM.

[Pyromaster2003]

Cheers for the advice you must be talking about a core burner though i only used end burners in the tests? I used straight meal so dont think the fuel can be any faster unless i used whistle..

Looks like il have to make a spindle for my 3/4 inch ones...i will try one more test by adding a longer nozzle and wider choke and see what happens.

[BrightStar]

Friday night, time to have some fun, so I made a rocket:



Did it work? Hell yeah... sort of... umm... actually, no. Video here:

Rocket launch (1448 Kb, Divx avi)

Mix was 63:25:12, nozzle - my usual stuff, the delay was 2cm of Karl's glitter comp (lots of Fe and Al), the top plug was 8mm bentonite with a 3mm off-centre hole - hand drilled with a sharp bit, the passfire was two strands of good blackmatch in a central plastic straw pipette - this burnt instantly in all tests.

I was wearing eye protection for the test but not full hard-hat PPE as I probably should have. I've no idea why the delay was so long - it ended up bursting a bit too close to me on the ground

Any ideas what went wrong ???

Edited by BrightStar, 04 August 2007 - 06:46 PM.

[MDH]

Brightstar, I recommend you work in a device which signals your salute is about to go off and gives you two seconds. This way you can easily scramble and tell where it is if it is falling towards you.

[BrightStar]

Brightstar, I recommend you work in a device which signals your salute is about to go off and gives you two seconds.

Thanks, yes, that's kind of the idea of the glitter delay mix - it is very visible so you can see where the rocket its going. There should have been no other delay - the piped black match burns instantly.

I think the key here is to use two sections of black match, one secured in the passfire pipette, the other bonded into the motor with a BP slurry prime. I think the black match was probably dislodged at some stage, or the flame was blocked by loose clay causing the failure.

I have to say though, you won't find me firing big rockets without a hard hat in the near future...

Edited by BrightStar, 04 August 2007 - 06:41 PM.

[sasman]

Cant explain the long delay...it should have worked ok?..In the past few weeks i have made a few test rockets but not put on any payloads .. but i have made 1 tonite that has a small payload.. i didnt use black match i think its to much hassle..

I have used a thin layer of Tigertail as my delay comp.. the layer may not give a very long delay but like you have just found out it is better for it to go off quicker than slower ...