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-   -   B14 motor musings... (http://www.oldrocketforum.com/showthread.php?t=7425)

ghrocketman 07-22-2010 12:55 PM

FSI F100 and E60 motors were pressed around a large-diameter pintle.
Not sure about the D18 and D20 though as those cores were MUCH smaller.

Shreadvector 07-22-2010 01:11 PM

Quote:
Originally Posted by jdbectec
Now that we know all about B14's, and have a good idea on the Mini-Max's, Does anyone know how FSI cored/pressed their motors?


I don't know for sure, but I know they had at least 7 rammings in the F7 and F100. They added some propellant and rammed it in, then repeated until they were done.

Doug Sams 07-22-2010 01:30 PM

Quote:
Originally Posted by ghrocketman
The nozzle appears to be a standard "B4" profile nozzle diameter and shape.
I have seen some later B14's that looked more like B8's - they didn't begin to have the larger cores seen on the earlier B14's. It wasn't clear to me if this was due to worn out drills, substitution (ie, selling B8's as B14's before finally getting new cert's and name changes), or mislabelling.

(I posted a pic of the various B14 and B8 nozzles somewhere, but danged if I can find it now...) [Edit: It was on my old website, but I need to upload it to my new one.]

Doug

.

tbzep 07-22-2010 01:34 PM

Quote:
Originally Posted by Shreadvector
I don't know for sure, but I know they had at least 7 rammings in the F7 and F100. They added some propellant and rammed it in, then repeated until they were done.


IIRC, that's the way some of the Chinese motors were done, creating a pulsing thrust. I havn't flown my D5's or long burn C6's yet, so I'm only going by memory of what has been posted here in the past.

Shreadvector 07-22-2010 01:59 PM

Quote:
Originally Posted by Doug Sams
I have seen some later B14's that looked more like B8's - they didn't begin to have the larger cores seen on the earlier B14's. It wasn't clear to me if this was due to worn out drills, substitution (ie, selling B8's as B14's before finally getting new cert's and name changes), or mislabelling.

(I posted a pic of the various B14 and B8 nozzles somewhere, but danged if I can find it now...) [Edit: It was on my old website, but I need to upload it to my new one.]

Doug

.


I think there was a later (possibly Centuri blue or green casing era) version of B14 make with a deep tapered core rather than the core with two steps seen earlier. It was much deeper than the B8/C5 core.

blackshire 07-22-2010 08:09 PM

Quote:
Originally Posted by Shreadvector
I think there was a later (possibly Centuri blue or green casing era) version of B14 make with a deep tapered core rather than the core with two steps seen earlier. It was much deeper than the B8/C5 core.
I have one of those blue-casing motors (a Centuri B14-7, Date Code: 110 1 73). Its nozzle is *very* wide and is almost cylindrical in cross-section, rather like the "nozz-hole" orifices in the Quest MicroMaxx motors. The tapered propellant grain void looks conical (it may be cylindrical for the upper 20% or so, but the foreshortened view makes it difficult to tell).

I also have an Estes B14-5 (Date Code: 21J5), whose nozzle looks like a B4's nozzle (going from memory, as I don't have any B4 motors on hand). The nozzle is considerably narrower than the Centuri B14-7's nozzle; it is a straight-sided cone that narrows down to a short cylindrical section. The grain void beyond is almost cylindrical, being a gently-tapered cone.

For comparison, a Centuri B8-5 I have (Date Code: 10l8? [the bottom of the third character wasn't printed]) has a nozzle only slightly wider than that of an Estes B6-4 (Date Code: 10 A 10). The grain void is conical, with perhaps the upper 10% - 15% being cylindrical.

Doug Sams 07-22-2010 08:37 PM

Quote:
Originally Posted by Doug Sams
(I posted a pic of the various B14 and B8 nozzles somewhere, but danged if I can find it now...) [Edit: It was on my old website, but I need to upload it to my new one.]
Here it is: (The dimensions are nozzle depth.)


And here's a close-up:



Doug

.

blackshire 07-22-2010 09:03 PM

Thank you for posting these pix, Doug!

ghrocketman 07-23-2010 09:28 AM

I think the right most B14's in those pics are the "precursors" to the B8 motors that replaced them.
Functionally, those last produced "B14s" I theorize were actually B8's; I have some late B14-7's and I cannot tell ANY dimensional difference in them from the B8-7's from a year later even under magnified examination.

Shreadvector 07-23-2010 09:48 AM

Quote:
Originally Posted by ghrocketman
I think the right most B14's in those pics are the "precursors" to the B8 motors that replaced them.
Functionally, those last produced "B14s" I theorize were actually B8's; I have some late B14-7's and I cannot tell ANY dimensional difference in them from the B8-7's from a year later even under magnified examination.


here is a theory (based on nothing but a guess):

Motor manufacturers can change a design without recertification as long as there is no major change. Often a motor is redesigned because of a change in propellant (different sources of black powder) or a change in place of manufacture. Usually the new samples are submitted for recertification, sometimes with the same motor designation (like the Quest C6-5 made in USA, Germany and China). back in the 1970's they may have tweaked the B14 design and tried to keep calling them B14's, but then either decided to recertify them as B8 on their own or after the NAR told them to do so.

I still think there was a tapered bore version (deep large hole plus deeper tiny drilled cylinder) as well as a long tapered single bore version (like a B8 bore, but deeper).

Any photos or measurements of a 196's era English units B3 motor?

8.1.6 Any changes exceeding manufacturing tolerances

made to the physical design or chemical composition of a

model rocket motor, motor reloading kit, or component(s)

by a manufacturer after certification testing shall be reported

to the recognized testing organization that originally

granted the certification prior to sale or shipment. If

the changes potentially affect characteristics measured in

the original certification testing, that testing organization

shall be permitted to require that samples of the changed
product be submitted for testing.



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