wiz@xroads.UUCP (Mike Carter) (12/03/87)
I am part of a reasonably sane assemblage of Amateur rocket enthusiasts
here in Arizona. What I'm looking for is a Mathematical
wizard who can reduce gas law equations into step-by-step calculations. I have
limited math background and need not only to be able to calculate volume
and density flows but also use the product to design nozzles. We're growing
weary of paying exhorbitant prices for minimally powered engines from various
suppliers. The K250 (producing 10 secs of 2300 Newton secs of thrust) is
a good engine, but the price is prohibitive for now. Using some knowledge
we have from various books, we are short a few pieces; (1) Gas Law math
made easy (I see you're laughing) (2) Better equations for nozzle design.
(3) Composite solid propellant formulas (we have 3, they are inefficient
and experimentation isn't our bag).
Thanks for your help.
Mike of the MAD Scientists Rocket Club.ornitz@kodak.UUCP (barry ornitz) (12/04/87)
In article <349@xroads.UUCP> wiz@xroads.UUCP (Mike Carter) writes: > >I am part of a reasonably sane assemblage of Amateur rocket enthusiasts ----------------? >here in Arizona. What I'm looking for is a Mathematical >wizard who can reduce gas law equations into step-by-step calculations. I have >limited math background and need not only to be able to calculate volume >and density flows but also use the product to design nozzles. We're growing >weary of paying exhorbitant prices for minimally powered engines from various >suppliers. The K250 (producing 10 secs of 2300 Newton secs of thrust) is >a good engine, but the price is prohibitive for now. Using some knowledge >we have from various books, we are short a few pieces; (1) Gas Law math >made easy (I see you're laughing) (2) Better equations for nozzle design. ===================== *Not Really* >(3) Composite solid propellant formulas (we have 3, they are inefficient >and experimentation isn't our bag). >Thanks for your help. > Mike of the MAD Scientists Rocket Club. Mike, There is a good reason for the prohibitive prices. The manufacturer has spent a great deal of time to optimize his design for performance, reproducibility, and especially safety. From your posting, I can see that you do not understand very much about thermodynamics, reaction chemistry, physics, and mathematics. Until you understand at least the fundamentals of these subjects, I question whether you can safely go beyond the commercial engines in your experiments. ------ It has taken many years of hard work to develop the safety record we have today with model rocketry. Please don't send us back to the days of amateur pyrotechnics. BTW, there is a model rocketry mailing list; are you a member? Barry ----------------- | ___ ________ | | | / / | | Dr. Barry L. Ornitz UUCP:...!rochester!kodak!ornitz | | / / | | Eastman Kodak Company | |< < K O D A K| | Eastman Chemicals Division Research Laboratories | | \ \ | | P. O. Box 1972 | |__\ \________| | Kingsport, TN 37662 615/229-4904 | | -----------------
gwyn@brl-smoke.ARPA (Doug Gwyn ) (12/04/87)
In article <349@xroads.UUCP> wiz@xroads.UUCP (Mike Carter) writes: >... (1) Gas Law math >made easy (I see you're laughing) (2) Better equations for nozzle design. >(3) Composite solid propellant formulas (we have 3, they are inefficient >and experimentation isn't our bag). Rocket motor design is a big subject. I remember finding a book "Guided Missile Engineering" by Ramo (the "R" in TRW) helpful. I suspect by now there are better references. As to the fuel, a really good one is likely to be dangerous too. Ammonium perchlorate, aluminum dust, and some organic fuel such as rubber are the ingredients of motors like the Shuttle's SRBs. The fuel has to be cured, and cracks in it can cause a motor to explode. You're probably better off using lower specific impulse formulations such as the old standby potassium nitrate and sugar (melted in a double boiler, and cast in place around a waxed rod to leave a hollow core when the rod is removed). This is still dangerous, but less so than some formulations. I don't recall the best proportions for sure, but I think it was 3:2 by weight. Some amateurs used to use zinc and sulfur, but I never had much luck with that. Commercial model rocket motors, at least the earlier ones, used highly compressed DuPont FFFFG black powder. You will also need a good igniter (it should spread flame down the whole core), and some fuels won't burn unless the pressure is high enough, which can make ignition more difficult. (Potassium nitrate/sugar burns okay at 1 atm.) Please be careful; any kids reading this should obtain adult supervision before working with potential explosives. The adults may be uncool, but they've learned how to be cautious over the years.