View Single Post
Old 07-21-2010, 11:00 PM
blackshire's Avatar
blackshire blackshire is offline
Master Modeler
Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 6,162

Originally Posted by Doug Sams
I think that's essentially the B8/C5.

My take is that for the more aggressive (steep) core of the B14, if you tried to merely ram it, that you wouldn't get the powder to pack tightly around the pintle (I think that's the right term) with the result that the core wouldn't be formed properly.
Yes, that's the most common term (pintle) for it that I've encountered, although in the book "All About Rockets & Jets" by Fletcher Pratt, the section that describes and illustrates Skyrocket motor pressing calls it a "thorn."
Originally Posted by Doug Sams
Since it's a powder being rammed (and not a liquid), you don't get true hydraulic behavior so the vertical pressures in the casing during the ram are greater than the horizontal forces - there's not enough force to pack the powder tightly around the core.
Indeed--up to a point, as long as it is tapered and not cylindrical (as was the pintle used in the B8 & C5 motors, as well as the conical thorn often used for pressing skyrocket motors), the pintle or thorn can apply sufficient vertical (bottom-to-top) pressure to the black powder grains to force them together into a solid mass when the grain is pressed.
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
All of my book proceeds go to the Northcote Heavy Horse Centre
NAR #54895 SR
Reply With Quote