1 lb rocket question(s) from a new guy

[Guest no6]

And by the way, I've fired 13 rockets since my initial failure and each has been a success.

 

I'm using the simple formula of 60/20/10/10.

 

60gr KN03

20gr 80 mesh hardwood charcoal

10gr air float hardwood charcoal

10gr sulfur

 

My best results (meaning fastest rocket) have come when running the KN03 through a coffee grinder before hand screening the ingredients together ("green mix").

 

I also made a small batch of this mix using only 80 mesh charcoal (30gr). The rocket lifted about 6" upon ignition, hesitated for about a 1/2 second and took off very cleanly. The flight was much slower but the height was about equal. And it was nice to be able to watch the entire flight (fired during the day). It landed like a lawn dart about 75' away. This was the first spent rocket recovered. The stick is reusable with about 1/8" of charring. The nozzle is still round though much worse for wear. The inside of the tube is charred badly. But I think this thing comes down cool enough to not start a fire.

 

Thanks for all the help and ideas, guys. I spent today building, spiking and pasting my first few serious canister payload shells. We'll see how that goes.

Edited March 7, 2011 by no6

[Mumbles]

Most of the time a salute is placed on top of the rocket. The relative height can be calculated by the delay between the flash and the sound, much like lightning.

[Guest no6]

But you wonder about the rocket curving away.

[Mumbles]

It at least gives you a vague idea of where you're at. Do you need to be able to retrieve the rocket in order to get the info off the altimeter?

[Guest no6]

Unfortunately, yes.

[Guest no6]

Any ideas?

[dagabu]

Hmmm, altimeters are tricky. I only tried this a couple times with a Perfectflight altimeter since it costs $100.00 and glued it into a standard rocket nose cone with a shock cord and triangle ripstop parachute (made for high speeds). I put a sprinkle of BP on top of the clay bulkhead and a wad of Borax treated paper towel on top of the BP. The tube was 12" long, 1" ID and was a standard BP spindle with fuse powder as fuel. It had two increments of fuse powder for delay.

 

It was a calm day with East winds of 40 MPH at 1500' ASL (we are 960' ASL on the ground). The rocket launched straight up, took a gentle right turn into the wind about a second into the flight, popped the chute about 5 seconds into the flight and I retrieved the nose cone from a swampy area but got hung up on milkweed so it stayed dry.

 

The Perfectfligt stores three flights and it recorded 2166' ASL. (1206' above the ground).

 

The second time it lawn darted and the nose cone was crushed at the tip. I had to repair the altimeter and decided to not shoot it again on a pyro rocket.

[donperry]

I'm wondering if I car hit 1km with single stage rocket. Rcandy

 

I'm also going to try some small bp cored rocket but i want to know if those can be cored by drilling like sugar kno3

Edited March 8, 2011 by donperry

[dagabu]

If the fuel lasts long enough and the thrust is constant then it should. That's the beauty of R-candy fuel vs BP, the burn can go on for much longer with a tighter nozzle.

[donperry]

The other ques is if the dry mix would be sufficient. Guess Ima have to test it

[dagabu]

If you crystallize it first then I see no reason why it wouldn't work but this is rocketry, I would test a batch first. I use a big covered skillet when making R-candy, I make a 1 kilo batch at a time and cast all of my grains at the same time. The granular method (Grind up the R-candy after its done) sounds like a great idea and if I ever catch up on my rockets, I am going to try it too.

[moondogman]

I love this thread. It answered many of the questions I had in my head that I couldnt figure out how to ask yet.

 

Steve

[Guest no6]

How big should the pass fire hole be in the bulkhead for this size rocket?

 

I drilled (by hand) my pass fire hole on 2 rockets with 1/8" bits at the edge of the tube. No go. Too small? Put a pinch of BP in there?

[dagabu]

no6,

 

The passfire hole is just that, it 'allows' the fire to pass but there has to be an instrument in place to carry the fire such as blackmatch or black powder or fast paper fuse in the hole and in intimate contact with the fuel grain in order to carry yhr flame to the heading.

 

I have had 100% success on lighting shells since getting rid of my bulkheads and just pressing fast delay on top of my fuel and laying fast paper fuse (the three strand type) on the surface and into the shell. I know that you cant do that with R-candy if you use pre-cored grains but you can if you ram it on top of a spindle.

[WonderBoy]

No6, I do as you said; I drill a 1/8" hole through the bulkhead near the tube wall. Then I use the back of the drill bit to lightly hand press into the hole a small amount of whistle mix(preferred) or BP. I then scoop in another small amount of whistle or BP and, using hand pressure, press it on top of the bulkhead so there is a thin layer covering the clay.

For passing fire to the heading I use a 1/4" tube, or similar, in place of the time fuse, and stuff a few pieces of blackmatch into it so it is a snug fit, with at least one piece long enough to touch the mix pressed on top of the bulkhead. This probably isn't necessary, but it's cheap insurance. I have yet to have a failure with this method.

Edited March 13, 2011 by WonderBoy

[Guest no6]

You two have been very helpful. Thanks.