There is too much solid propellant above the core, which doesn't produce nearly as much thrust as the cored portion. The cored bit burns, and gets the rocket up in the air, but the uncored bit doesn't have enough thrust to keep it there. One quick and easy solution is to put less uncored propellant on top of the cored portion, so that the payload will be ignited before it tips over. This way the rocket would go to your estimated 60-70 feet, then discharge the payload.
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.
