FWIW, my understanding was that they started with something approximately equal to a C6, then drilled it to the B14. By the time they were thru drilling, enough BP had been removed to drop it one impulse class. I doubt it was a full C to begin with, but still a bit more than a B.

Doug

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YORF member #11

doug, I of course was being both totally facetious and politically incorrect with my suggestions for drilling B14.

I do think that there is probably some combination of advanced technologies that in combination might make drilling BP much safer than perhasp its was in the past.

Going way back to the past with pyrotechnic skyrockets, they use to drill cores in some instances by running the drill through a wet sponge to reduce the hat generated, as heat generation due to friction is what can cause the Bp to detonate.

This leads me to believe that perhaps what we need is a drill bit that is hollow ith a gas or liquid cooled material to keep the drill bit way below the autoignition temperature of the pressed BP.

I have a technical report provided to me from Estes-Cox in which the autoignition temperature of their pressed Bp is on the order of +500 F. (this is from memory so it may be off some) SO if you drill in small increments at a low speed to maintain a small amount of frictional heating, add a drill bit that is cooled somehow, perhaps add a coating to the drill bit like maybe PTFE to also reduce frictional heat, a machine to drill might just be possible. A CNC mill that could be controlled by precise depth increment,rotational cut speed, etc and a cooling solution might work.


EDIT I just found the R&D report and the values are:

31 samples tested
all ignited between 562 and 627 F
the average ignition temperature was 589 F

Another factor involved with highly pressed BP is known as its Dead-Press Pressure which means that most explosives become much less sensitive to explosion when they are pre-pressed to a very high pressure such as BP in a motor is. .


Another idea to be usd in conjunction would be to use their successful B8/C5 formed core design and then just drill out the rest of the core.

The combination of the two might just work.

Another solution might be that some super stif materials like titanium or tungsten might be used on the spindles and drifts used to form fulled cored motor. Its my undrstanding that current materials used and the pressures they are subjected to, result in easy breakage , wear and tear,etc. Perhaps the tooling needs to be mad of some aerospace grade metals combination?


terry dean

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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.

Actually the drilled core was quite skinny. 1/16" diameter x 0.4" long with the pressed core being nearly 3/16" dia x 0.15 long.

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Roy
nar12605

This is simple to handle and does not require a "sensitive" sensor. Just use an optical sensor to see if the pintle is still there between motors. If the pintle tip is missing, then the previous motor is suspect.

It would come down to how often this happens. I see no reason why it should be a frequent occurrence. Are the nozzles pressed with a pintle? Why do they not have the same issue? Or are the pressures much lower when compressing the nozzles?

As long as the plunger and nozzle have the same relationship, the pintle will always be calibrated in proper position if the nozzle is used to center the engine on the pintle.

Then again, I will happily read that I've totally overlooked serious machining issues. Machining discussion fascinates me. Still, I do not see why a compress-around-a-pintle machine cannot be made safe and efficient.

Ah, reading further I see that the pintle would need to be very thin and relatively long.

Hmmm. What if the pintle were made out of something flexible and compressible rather then hard? Then use a separate pintle for every engine and extract it after manufacturing. It would need to have great linear strength so it could be extracted without snapping. Carbon fiber rods?

Hee, hee, or make it out of frozen carbon dioxide and let it evaporate after engine forming...

Hmmm or a high tech balloon device which is volume controlled. The pressure is increased to maintain constant volume such that the air (or nitrogen, or argon) pressure inside matches the compression on the outside. That should do away with pintle snaps. A leaking pintle will be obvious to the pressure controller. I'm just not sure if we have gas compression technology that can do the job affordably.

It's the depth that dictates how full the case has to be. I'm assuming your depth number is only the depth into the BP and excludes the nozzle depth. In some recent measurements I took, I got (IIRC) ~0.75" total depth.

I envision the burning pattern to be sort of like an umbrella opening with the result that the shallow sides tend to catch up with the deeper core during the burn such that there is little BP left after the initial spike and hence little tail on the thrust curve.

Anyway, what I saw in my comparison was that the core got narrower over time as it transitioned from B14 to B8.


I seem to be struggling to say what I need to My understanding was the core was drilled in two steps. I assumed that one step was to get the deeper, skinny section, and the other was to open the nozzle. But I could be wrong.

Doug


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YORF member #11

It's my understanding that creating a B14 motor required drilling a port roughly 1" deep through the throat of a B6 motor. It was a hand operation done over water. The port could not be made in the normal pressing operation because the required rams would need to be hollow to allow the removal of entrapped powder inside after a power stroke. The ram would simply be too mechanically fragile and could therefore break or dislodge into the machinery. Bad things, i.e. "kaboom" happen after that.

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Quando Omni Flunkus Moritati

great photo Doug.


anybody else have older and or other dated stamped B14 to compare port sizes over time?
especially mid to late 60'sand later 70's?


terry dean

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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.

Well, I have a few Estes B3-6's dated 12/02/67 - will that help?

Sean

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Those "old school" imperial-rated B3-x motors from 1967 actually test out to around a B16 with even higher avg. thrust than the original metric-newton-rated "drilled core" B14's that replaced them.
I'd like to see ANY of the high-thrust B's (drilled-core B14, pressed-core B14, or even the semi-port-burning B8) return in all the -0, 3, 5, 6, and 7 flavors.
Return of the C5-0, 3 would also be very welcome.
I'd be wholeheartedly in favor of discontinuing the C6-0, C6-3 and C6-5 completely if we could get C5-0, 3, and 5 engines.
The C5 series are MUCH more versatile to use than the C6; they can actually lift a reasonable amount of weight without a cruise missile flight.
The C5-3 (and old Cox 18mm D8-3) is the perfect BP engine for the Mars Lander and 1284 Space Shuttle.
Those two rockets fly barely so-so on a C6-3, but great on a C5-3.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !