35 replies to this topic

[maxman]

I have just made a 3" can shell that is about 4" in length. I wanted to use it as a rocket payload as I have no mortar. Unfortunately it weighs heavier than I expected at 350 grams.

Am I to assume from what I've read above that this would be too dangerous as a header for my biggest rocket which is 1lb?

I have two 1lb rockets made up so would it be possible to strap the two motors together to get this payload up? or is this going to be two dangerous?

Thanks

Maxman

[adamw]

I would say 'yes' - quite risky! What if one of the motors doesn't ignite? What if one is more powerful than the other, sending the rocket at an angle.

[Yugen-biki]

It's not very good as adamw said. I have tested something similar useing 2 small rockets. They tend to get an angel because it is close to impossible to ignite the two rockets at the exact time.

Edited by Yugen-biki, 07 November 2004 - 06:51 PM.

[maxman]

Well we did test it on Friday night! and it worked perfectly. We had 1x 1lb motor with 2x 4oz motors strapped to the side (like the shuttle) the payload was 3x4" can shell with a mixture of 3/8" stars glitter, aluminium, granite. Rice crispies coated in meal was the burst charge.

The payload weighed 350g and the total weight inc a 42" stick 8mm sq section was 688 grams. We recovered the three motors and stick which had a dead weight of 233g approx. (it was impailed deep in the earth, also seen on video)

The 1lb motor and one of the 4oz motors fired at the same time but there was a delay with the second 4 oz motor of a second. This didn't seem to cause any problems and can be clearly seen kicking in on the video.

I am without a capture card at the moment on this new PC but will make it known as soon as I can get the VHS-C tape onto the hard drive. Its worth watching (well I think so anyhow)

I do have a couple of stills of the device prior to setting it off if anyone is interested.

Maxman

[sasman]

Maxman How much do you normaly lift with your 1 lb rocket? I made a few for the 5th But struggled with a Total weight including stick of 190 ish grams..

Which i think is poor.. i have seen endburners on the net carrying a 1lb payload?.. Its easy to experiment if you have time..but sods law has stepped in and i have and will be very bizzy for the next few months..

So would like some advice on how to increase the thrust of the Rocket?..Other than drilling a longer core?..If i make the core to long they do produce more thrust but burn to fast.. and then dont go high enough..Have you experimented with core length or Dia?..Also something of a worry is the Stick? when they go up they come down fast? very Dodgy in a populated area?..I reckon the stick on commercial rockets are desinged to break in mid air so dont fall back to earth as fast..

[Kembang Api]

I had been shooting Chinese made rockets with 2 breaks (1.5 inches shell each) Here is the picture.

I had made the same rocket a couple of months back with the following spec.
1. Inner diameter 19 mm
2. lenght of tube 5 inches
3. 7 mm core burning type of rocket.
4. length of core is 70 mm
6. 750 mm (8mm X 8mm) wooden stick

I attached 3 inches shell (135 grams)on the rocket and it took off very well. I angle the rocket a few degree following the direction of the wind. I will send the picture soon.

Edited by Kembang Api, 11 November 2004 - 09:37 PM.