Re: Computer Program Design program for Skyrockets

LadyKate <ladykate@xxxxxxxxxxxxxxxxxxxx> fired this volley in
news:65655d39-ed21-4efc-8528-564b226e92e7@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:

On May 21, 12:40 pm, "shockwaveriderz" <shockwaverid...@xxxxxxxxxxxxx>
wrote:
dan:

just some modern day formulas as to how long the core should be
versus propellent length; core base diamter as a fucntion of ID;
length/thicknes fo heading as a function of case id..
stuff like that

I may be missing something -- I think you are asking your program to
do too much.

There may be too many variables. You need to tie one or two down.
For instance, the rocket mix makes a huge difference and will affect
the success or failure of any design. If you just settle on one mix -
let's pick BP - then there is a wide spectrum of energy levels
possible - all the way from the hottest that can be made to charcoal
briquette fuel. All of which can be successful but which will take a
different tool set, or application of said tool set, to optimize the
flight - or to even get off the ground.


I'll disagree. Just recently (and for the first time), I've started some
serious research into small rocket motors. I developed a friendship with
"The Sugar Daddy" Jimmy Yawn, and he's been assisting and teaching me.

The primary "signature" for a propellant seems to be its optimum "Kn"
ratio. That is, the best ratio of burning surface to nozzle size. It
requires some experimentation to develop a "best" figure. However, once
that is established, it's pretty easy to computer-model and build a
successful motor from just about any fuel powerful enough to serve the
purpose.

I don't have the figure at hand, but the rocket guys have characterized
the Kn figures for black powder. Intuitively, one can assume that a
slower fuel (more coal) needs a higher Kn ratio to develop the pressures
and burn rate necessary.

So -- it IS rocket science, and it can be modeled relatively easily.

LLoyd
.

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