would somebody that knows please xplain what the major differences there is between the APCP used in the SPace Shuttle SRb's and the APCP as used in Sport Rocketry Motors.
Isn't there a number of ingredients used in the SRB that aren't found in the sport rocketry motors? Isn't ther a difference in terms of particle size in the SRB AP than the AP used in Sport Rocketry motors?
tia
shockie B)
There is no major difference, although it does contain more aluminum than most of us use. The formula is publically available and easily made. Here is one source I found:
I launched my Magnum one time on a 5-grain 54mm K motor made with this formula (by a friend of mine), and it moved VERY quickly and achieved 5600 feet.
-- David
There is No major difference.
Actually, it's the other way around. There are just five ingredients in the SRB propellant: (1) PBAN binder; (2) Epoxy curative; (3) AP; (4) Aluminum; (5) red iron oxide.
As I look through over a dozen formulations for APCP prepared by amateurs, I see two with five ingredients. The rest have up to 11.
I can't answer the particle-size question authoritatively, but was told by an individual who is in the hobby motor business that the SRBs use exclusively 200 micron AP---same as most amateurs.
Best regards -- The other Terry
I think the earlier SRB propellant used PBAN as the binder. I'm not certain if the current formulation uses HTPB or PBAN.
John
When people ask, I always get them started with a four ingredient propellant. It's AP, Al, HTPB, and MDI.
-JT
snipped-for-privacy@hotmail.com wrote:
So you want to torture them and "incentivize" them to buy your commercial propellants.
Jerry
Do you have anything constructive to add? Like a good formula for people to start out with?
That's not what this thread is about.
The above formula (shuttle propellant) is a RPIA to make and "pack".
Donny says vacuum!
When aluminum burns, the immediate result is gaseous Al2O3. It takes a lot of energy to vaporize that material, and when it precipitates as solid smoke particles, you get that energy back as heat - with which to expand gas. (You also get light, BTW.) It takes some time for the precipitation to occur. In a small motor, most of the the material would be ejected first. Thus, it isn't productive to have large amounts of aluminum in sport rocketry motors.
-Larry (That's a remarkable link. Thanks! ) C.
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