snipped-for-privacy@gmail.com (David Harper) wrote in news: snipped-for-privacy@posting.google.com:
How about the residue and slag deposits keeping the slugs in place?
snipped-for-privacy@gmail.com (David Harper) wrote in news: snipped-for-privacy@posting.google.com:
How about the residue and slag deposits keeping the slugs in place?
It's possible, but I doubt the slag and/or residue would form bonds/barriers in the chamber to prevent grain movement, since the solids are most likely molten until exiting the chamber. Even solids that did form on the chamber walls would have poor mechanical properties at that elevated temperature.
Dave
Yea, but that's later, after the moter is fired.
snipped-for-privacy@gmail.com (David Harper) wrote in news: snipped-for-privacy@posting.google.com:
But the fuel grains are usually a fairly close fit,any deposits would prevent movement.Aren't you supposed to wrap tape around them if they are too loose?
Nothing can prevent movement of grains after ignition short of gluing them to the liner.
Pressure and massflow are powerful forces.
Powerful enough to send stuff to space with a device smaller than 2 cars.
Jerry
Does it actually matter whether the grains remain in their original position or slide aft? It might change the center of gravity a bit... what else changes?
(Has anyone ever done side-by-side firings with loose vs. glued grains?
-dave w
Only if they slide suddenly. Propellant is not all that shock resistant from physical breakage.
The AT 29mm G240 in any rocket works fine. Stick fins on it and about
1/2 of them fail due to excessive G's dislodging and cracking the grains.Been there, done that too :)
Jerry
When did AT make a G240? (It seems they have discontinued a lot of types - especally single use, and smaller ones in general - over the years, based on such things as motor lists included in some simulation programs...)
-dave w
I've never case bonded KNSU BATES grains in PVC, but experience with standard core grains leads me to believe it is not a good idea. My early PVC sugar motor experiments were pretty disappointing with case bonded cast grains; routine overpressure CATOs. I believe my problems were caused by differing modulus of elasticity between the (brittle) KNSU and the more elastic PVC; the chamber (core) pressre would split the propellant grain since the PVC allowed expansion. The increased burning area would overpressurize the case and FOOOMP! Free standing grains improved reliabilty greatly as the PVC could expand while the pressure was equalized around the grain and prevented cracking/splits.
When Jerry (AT's first dealer) bought them.
Jerry stopped buying them.
That was the same clip I was going to suggest :-)
Ripped it from a Discovery Channel program (has sound)
Stephen
Or..... We could just look into a spent motor and see if we can see anything that would tell us what happened. Naw, I think the discussion of theories is much more fun! :-)
Cool - thanks Stephen! I saw Aurora fly two weekends ago at Wayside, Texas. Some motor ... SOME ROCKET!
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.