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  #21  
Old 01-02-2007, 10:01 PM
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Carl, how do you plan to make the core burners?
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  #22  
Old 01-02-2007, 10:08 PM
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Originally Posted by Eagle3
Carl, how do you plan to make the core burners?
18mm and under will be drilled in post production by another separate machine completely automated. The larger ones... we will cross that bridge then.

The largest core burner initially will be the 3/4C19 - 7.5ns. That was the only booster I liked better than the B14.
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  #23  
Old 01-02-2007, 10:26 PM
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Quote:
Originally Posted by Carl@Semroc
Here is a preliminary lineup of the sizes we are looking at:Engine Family Portrait This list is tentative and will be made more final over the next month so we can apply for EX-numbers. This is confidential, but your input is needed so we don't overlook something.

The propellant for all this batch is BP, but we are looking at "steam generators" later for contests.

The DECAP's will be a welcome addition for some. They will be available in 2-9 seconds in standard .5g load and -X with 1.2g load. A plugged version will be included as well as an Ejection Charge only version that takes standard igniters and will come in .5g, 1.2g, and 2.0g versions.

The order of release will be based on discussions here. The smaller 18mm and under machine is being built first. Engines over 70mm long or over 18mm in diameter will be done on the larger machine.


Carl;

Given the process in front of you, about how far away is Semroc from putting the first few on a store shelf somewhere?
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  #24  
Old 01-02-2007, 10:39 PM
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Hello Carl,

Do you plan to manufacture your own igniter to ship with these? It would seem the 29mm PB would need a special igniter.

The 24mm and 29mm would be exciting for two stage rockets based on the LT tubing sizes. The first thing I think of when I see these 24mm and 29mm BP motors in your diagram is staging them.

.
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  #25  
Old 01-02-2007, 10:40 PM
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Quote:
Originally Posted by John Brohm
Carl;

Given the process in front of you, about how far away is Semroc from putting the first few on a store shelf somewhere?
There are too many variables to solve THAT equation!

Seriously, you are involved in the earliest stages and will probably see the whole thing evolve, warts and all.
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  #26  
Old 01-02-2007, 10:42 PM
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Originally Posted by snaquin
Hello Carl,

Do you plan to manufacture your own igniter to ship with these?
We have been working on an igniter for the small engines. The larger engines might need a different design.
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  #27  
Old 01-02-2007, 10:56 PM
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Carl,

Concerning those PB (Port Burner, or cored) motors, you said they would need to be drilled. What is the manufacturing problem about using, say, a Teflon-coated mandrel run up through the nozzle during the pressing operation? Couldn't the BP be pressed around the mandrel evenly and completely in a single pass of the ram? Or even have a double-piston, one pressing down from the top, the other pressing the mandrel up from the bottom, to ensure the even distribution of powder?
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  #28  
Old 01-02-2007, 11:02 PM
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Quote:
Originally Posted by CPMcGraw
Carl,

Concerning those PB (Port Burner, or cored) motors, you said they would need to be drilled. What is the manufacturing problem about using, say, a Teflon-coated mandrel run up through the nozzle during the pressing operation? Couldn't the BP be pressed around the mandrel evenly and completely in a single pass of the ram? Or even have a double-piston, one pressing down from the top, the other pressing the mandrel up from the bottom, to ensure the even distribution of powder?
It's not that easy. You can only pack a small amount of BP at a time. It bonds to the walls. The mandrel fills up and can't be cleaned on-the-fly.

It is really hard to explain.
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  #29  
Old 01-02-2007, 11:13 PM
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Quote:
Originally Posted by Carl@Semroc
It's not that easy. You can only pack a small amount of BP at a time. It bonds to the walls. The mandrel fills up and can't be cleaned on-the-fly.

It is really hard to explain.


So the pressing action is multi-layered? You fill a small amount, press it, fill some more, press that, etc... until you build up the final amount of powder, then perhaps, you give the whole mass one final pressing to reach the desired compression density?

That explains why the mandrel approach would be difficult. You would also need a mandrel at each fill and press station, and getting the mandrels aligned correctly each time would be difficult. The drilling process can be done in one pass after the cylinder has been filled and final-pressed.

It's a shame the BP couldn't be hard-pressed into pellets separately, then soft-rammed into the cylinder during the final assembly. I know this brings possible deformation and cracking issues into the pellets, leading to grain failures (CATOs).

I'm learning as we go along. This was new information to me. Thanks!
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  #30  
Old 01-02-2007, 11:19 PM
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Quote:
Originally Posted by Carl@Semroc
There are too many variables to solve THAT equation!

Seriously, you are involved in the earliest stages and will probably see the whole thing evolve, warts and all.


Will one of the objectives be then to actually produce a USA-based FAI acceptable competition motor?
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