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  #11  
Old 09-25-2016, 05:35 PM
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Quote:
Originally Posted by tbzep
George, now that you mention it, I've seen B14 comparisons where the nozzles are not the same size and different core depth, with later production looking a lot like the B8. I believe the consensus was they quit drilling and started making something like the B8 before Estes ever released the B8 by name.


I purchased my first box of B14 motors from Centuri probably sometime in late 1976. By that time of course the Centuri motors were once again being made by Estes.

I was really looking forward to seeing the 'really deep' core on the motors. But, to my sad surprise when they came with my next order, they did not have any deeper of a core than my other motors in my meager stock at that time. I thought at the time that maybe there was a manufacturing defect in them, but they operated just fine in my Screaming Eagle.

In more recent times though, with various discussions about B14 motors and how they were made, I assumed they had just stopped coring them.

Several years ago I did get a number of boxes of very early 70s Centuri B14s and they DID have the deep core.

So yes, I think at some point in the 70s they just stopped drilling them, but never really announced a spec change on them.

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  #12  
Old 09-25-2016, 05:48 PM
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Quote:
Originally Posted by tbzep
George, now that you mention it, I've seen B14 comparisons where the nozzles are not the same size and different core depth, with later production looking a lot like the B8. I believe the consensus was they quit drilling and started making something like the B8 before Estes ever released the B8 by name.
Here are some pics from a few years ago. (BTW, the B18 annotation is supposed to be B8.) The dimension is the nozzle depth.

Doug

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  #13  
Old 09-26-2016, 06:38 AM
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Quote:
Originally Posted by Doug Sams
Here are some pics from a few years ago. (BTW, the B18 annotation is supposed to be B8.) The dimension is the nozzle depth.

Doug

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Doug, if that third engine is truly a B14, how did Estes get away with such a small diameter on the nozzle opening? It looks the same as the last one (B8).
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Old 09-26-2016, 07:05 AM
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Quote:
Originally Posted by mojo1986
Doug, if that third engine is truly a B14, how did Estes get away with such a small diameter on the nozzle opening? It looks the same as the last one (B8).

That's what I was talking about. Estes stopped drilling them and began using the standard pintle method. The resulting B14 ended up being very close to if not the same as the "new" B8.
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Old 09-26-2016, 10:39 AM
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Quote:
Originally Posted by tbzep
That's what I was talking about. Estes stopped drilling them and began using the standard pintle method. The resulting B14 ended up being very close to if not the same as the "new" B8.
Yes. And based on earlier conversations here, I'm inclined to think that was indeed the case, that pintle-produced B14's were in fact the earliest versions of what became known as the B8's.

The only discontinuity in this theory is the depth of the nozzles. When I took those pics (~10 years ago), I was careful to properly measure the nozzle depths. The presumably-pintle formed B14 measured 0.75" deep while the B8 measured 0.6". So there was some difference. But this may simply be an evolutionary step - after some volume of production with a 0.75" pintle, it may have become necessary to use a shorter pintle due to excess wear or breaking. (There's a question for Mr Brown )

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  #16  
Old 09-26-2016, 04:54 PM
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Some images from old Estes catalog scans on http://www.ninfinger.org

1970 catalog, pages 92-93, engine chart. Note the burn time of the B14 as .35 second.



1969 catalog, page 76, comparison of B6 and B14. with some dimensions. Notably the throat diameter:



1968 catalog , page 52. The drawing shows a deeper drilled core than the one above, and IIRC that was more inline with other info I’d seen. Also, given the thrust curve shape, how it drops to zero SO fast, the core would need to be so deep as in the drawing below, that there would be little to no propellant left to burn forward of the core, once the flame front reached the sides (A tiny bit of an arc of unburned propellant near the casing sides and bottom of the time delay being consumed during the steep drop-off).

So, what is really needed for this thread is for someone with a very old Estes B14 from 1970 or before, to measure the core depth. .75 inches from the casing bottom seems WAY shallow for the original “real B14” thrust curve..

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  #17  
Old 09-29-2016, 11:52 AM
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I recall that those old B14s were ideal for putting up a 2-stage Class C egg-lofter in a hurry!
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  #18  
Old 09-29-2016, 07:40 PM
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Quote:
Originally Posted by Doug Sams
Here are some pics from a few years ago. (BTW, the B18 annotation is supposed to be B8.) The dimension is the nozzle depth.

Doug

.


Just for comparison, below are the early Estes English pre-cursers to the B14, the B3's:

Sean
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  #19  
Old 09-30-2016, 04:30 PM
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Prior to the B3, Estes had a MAJOR thrust "B" through 1961.
A B16 existed. Those things had a complete propellant burn time of .07 secs with 16lb of peak thrust.
That is a REAL kick in the tail.
If it could be done back then WITH almost ZERO automation in production, it could be done NOW much more safely.
The sissies and mamby-pambys just won't do it.
We can't even get the moderate-thrust B8 and C5 pintle-port motors back.
REAL BP engines are PORT burners !
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Last edited by ghrocketman : 09-30-2016 at 04:46 PM.
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  #20  
Old 10-01-2016, 06:24 AM
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I'm gonna have to take a hard look at the Centuri B14's I still have...
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