Rocket Drawings and Design
#1
Posted 05 August 2004 - 01:42 PM
This is a drawing of a recent rocket
I am using Rhodri's formula 61:34:8 and then adding 20% 75:15:10 for the fuel
(Thanks for that one)
Overall with stick this weighs 75g.
I've only launched one, which went up to about 60-70ft quite quickly but then slowed, turned 180, and headed back down with the still motor burning reasonably fast.
Could someone give me advice on how to modify to achieve more height and fully utilise the motor?
Is it a good idea to make one with an entirely hollow core ie:full length?
A bit of advice would be much appreciated
Cheers
#2
Posted 05 August 2004 - 01:45 PM
#3
Posted 05 August 2004 - 05:35 PM
Another option would be to use the same length of propellant, but increase the core length to achieve a shorter delay (since that is a reason for the uncored section - to allow the rocket to slow a little before the stars discharge). However, this may result in the rockets blowing up, and you might need to use a slower burning propellant. This method would probably increase the height the rockets reach over your current 60-70 feet. With either of the above, I would probably reduce the delay section to a little uner half its current length.
Alternatively, you could try to reduce the mass of the rocket until the uncored portion can confortably carry it after the cored bit has finished burning, in which case the rockets would ascend higher than they do at present.
[EDIT] Oops... sorry, I didn't realise you'd relocated the topic to a better area until after I made this post, as I'm in the habit of reading topics bottom to top of the list.
Edited by Phoenix, 05 August 2004 - 05:44 PM.
#4
Posted 05 August 2004 - 06:45 PM
The core in large rockets is sometimes star shaped. This means that the thrust/time relationship can be controlled and the initial burn produces usable thrust sooner after ignition.
Keep mannequins and watermelons away from fireworks..they always get hurt..
#5
Posted 06 August 2004 - 06:51 AM
Longer core test this weekend, I will post the result
Cheers
#6
Posted 06 August 2004 - 10:44 AM
This weekend I will be placing a 3" dia payload which I hope will burst within seeing distance.
I have no doubt over the rockets ability to lift the payload as my initial test on the motor was to place it inverted in the ground a bit like a fountain.. I had to dig nearly 2' down to recover the tube.
Mark
PS RichardH.. you think UKRA would pass this as a hybrid motor ?
BPA L1 & L2
#7
Posted 06 August 2004 - 10:59 AM
Just a quick question or two
Do you load your rockets wet, with alc or water, or dry?
Presumably you are using tooling to get the 6-3mm taper?
#8
Posted 06 August 2004 - 05:38 PM
Yes, I am using tooling which is from Greg Boyd.. not sure of the web site but it will show up on a search of the forum.
Mark
BPA L1 & L2
#9
Posted 07 August 2004 - 03:11 AM
Anyway, I basically said what Phoenix did, just in my usual more verbose manner.
http://www.vk2zay.net/
#10
Posted 08 August 2004 - 04:03 PM
But also tested a 88mm rocket, 12mm i/d filled with 75:15:10 black powder and went at least 200ft. superb! These are only my estimates on height but i was impressed!
Ive only been making wheels, rats and fountains before this so last night was pretty cool.
Thanks All!
#11
Posted 09 August 2004 - 10:44 AM
(Alany, please excuse me - it was I who deleted the posts - yours and mine included. I attempted to do some housekeeping and messed it up )
Oh well!
#12
Posted 26 August 2004 - 10:53 AM
chemicalwazi, I thik the drawing you showed would work well with straight meal or meal and 10% C as I have had great success with a rocket of similar dimensions recently.
#13
Posted 26 August 2004 - 01:14 PM
Think I found out why it went like a bat out of hell, I used my perc BP and not the KNO3 bp which may have made it a bit more energetic. Also my perc BP had been milled a while longer so a better performer overall.
Mark
ps: Anyone used pyrodex in place of BP for anything ?
BPA L1 & L2
#14
Posted 26 August 2004 - 07:32 PM
Yeh, that sounds about the same.. +/- 10mm to +/- 6mm.
Think I found out why it went like a bat out of hell, I used my perc BP and not the KNO3 bp which may have made it a bit more energetic. Also my perc BP had been milled a while longer so a better performer overall.
Mark
ps: Anyone used pyrodex in place of BP for anything ?
Hi Mark
Could i ask the formula for your Perc BP?
Be nice to try against my standard BP. I also have just been given a Ball Mill and my 11mm lead shot has just arrived. Cant wait to give it a go
Thanks maxman, that's another one for the test.
Paul
1 user(s) are reading this topic
0 members, 1 guests, 0 anonymous users