Half inch rocket with shell

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coalman
Posts: 105
Joined: Mon Feb 03, 2014 7:53 pm
Location: Swindon

Half inch rocket with shell

Post by coalman »

I had my first 1/2" + 2" shell launch the other day. I've been putting it off for ages because I read somewhere that the maximum payload for a half inch should be 60g and I couldn't work out whether payload is the shell or the whole shebang. With my total launch weight being 96g on top of experimenting with titanium addition to the fuel and putting more in than I intended, plus it being my first proper shell; so I had totally convinced myself that it wouldn't get very far. I set up a very long fuse and got 100ft from the launch site, with the camera set up and started beforehand.

I needn't have worried about it not getting very far, the tail was spectacular and the rocket reached a really good height but the shell burst 5.9 seconds after ignition - Probably at about 60ft, on the way down.

So here are some questions.
  • What sort of apogee heights are likely with a good 60:30:10 fuel mix?
  • What is an optimal star size/burst height/time for the shell? My guess would be 3 secs from ignition
  • How would I best bring forward the burst time - I used a visco passfire into the shell?
  • And from a safety perspective, should I have done anything differently?
I find that if I don't use some sort of end cap I am more likely to get a cato.
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Pyro-Gear
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Posts: 3034
Joined: Wed Jul 10, 2013 8:24 am

Re: Half inch rocket with shell

Post by Pyro-Gear »

I can lift 60grms on a 10mm, with the ½ set as like all my tools there is no need for a clay top plug or any type of fuse to pass fire in to the header, basically make your shell with a ¼ inch tube central to the equator with around 4mm exposed after pasting.
Ram the rocket or press to within 4-5mm from the top of the tube, now take the shell and add a little BP in to the pass fire tube and attach to the motor that’s it, no need for visco if you are using a top clay plug it is likely you are hitting what’s left of the delay far to early hence the cato effect you are seeing.
You should be looking at 150ft to burst with an all up weight of around 130-150grms try this any problems give me shout.
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