23 replies to this topic

[dr thrust]

have you per-chance read congreve's book?
im just wondering.about core design and forming of the core

Edited by dr thrust, 24 June 2011 - 06:02 PM.

[Mortartube]

Personally no. But my boss when I worked at Wells had and relayed the information.

[dan100]

this is interesting. slightly smaller engines but cant be too far off "how they do it"


dan.

[dr thrust]

i cant for the life of me work out, what they are doing?
pouring in water and pushing in a stick with cloth on the end, to compress the fuel grain?
On a 10 kg motor, and yet i need a 20 ton press to make a reliable 3 lb'er?

Edited by dr thrust, 24 June 2011 - 05:45 PM.

[dan100]

i cant for the life of me work out, what they are doing?
pouring in water and pushing in a stick with cloth on the end, to compress the fuel grain?
On a 10 kg motor, and yet i need a 20 ton press to make a reliable 3 lb'er?

you need holy water


me neither, but heres what i think, the core and grain must be quite solid for "big drill man" and pokey stick man" to do their jobs without wrecking it.
the water may be to inhibit the burn in the early thrust phase to prevent cato's on the rack, it may even be oil but i would expect it to be added to the comp before filling the case.
i have asked the original poster of the video whats happening but no reply yet hes a moderator on another forum aswell so not too hard to track down.
it doesn't seem like an exact science to me just experience and good judgement i may be wrong but early rockets were all bamboo and bp made by people with no official education.
dan

[dr thrust]

ahh finally worked out how to get the youtube video thingy on a post
anyways.. check out those crazy chaps sat on the rocket rack, part of the fun?

[bangkokpyro]

Thai rockets in all sizes from 2Kg to100 kg are pressed with a crude hydraulic press of some sort to 2 tons or more pressure on the comp.
The core is drilled throughout the rocket length right to the end and they never press the rockets with spindle type tooling.
The comp is very coarse rough screened B.P. You can see the Sulphur and Charcoal grains in it clearly and it feels gritty. (it also has a lot of water added to it before pressing).
The comp hardly burns when ignited in a pile on the ground.
Days or weeks after the rocket has been pressed some of the comp has dried out and just before the rocket is launched water is poured into the bore and wooden cloth covered dowels in different diameters and lengths are used to absorb some of water and to smooth the inside bore to just the right degree that the rocket does not burn to fast and CATO.. The rocket is not lit from the nozzle end but from the far end of the bored hole using a small bag containing about 5 gms of B.P in contact with some wire wool and ignition wires' attached to a 12 volt car battery. Nozzles are normally wooden.
These rocket are never made for 'artistic' and pretty effects so they contain no matals or coarse charcoal for sparks, their sole purpose is to take as long as possible to reach the maximum height and return to earth.
The Thais place bets on the time achieved and the longest flight time wins. They are always fired in the daytime. Some builders add small amounts of granulated rubber or caster oil to the comp to produce black or white smoke making then easier to track after lift off. Typical flight ime for a 2 inch ID rocket (6KG) is around 190 seconds from launch to hitting the deck again.

Edited by bangkokpyro, 06 July 2011 - 11:50 AM.

[bangkokpyro]

now thats a rocket, you would know more than me but im geussing its a retarded fuel with extra charcoal or mineral oil some of them had different coloured tail's so maybe both[on different rockets] truly amazing how they get 4 minutes airtime
is this the same place they make 4 metre diameter girandola's?
dan

Here is a video of preparation and launch of a 'small' Girandola. Pretty much the same comp as used in the rockets. Rammed into steel pipe with 2 5/8 ID nozzles offset from centre line approx 7 degrees.

[dan100]

thanks for clearing that up its very interesting seeing different methods and finding the facts, ive seen your vids and subbed weeks ago in my search to source information on these. the girandola's are also something quite special to me especially the big ones with 4 nozzles, ive always wanted to light one myself with long sticks, i feel a holiday coming on maybe next year though.

dan.