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  #31  
Old 01-03-2007, 12:32 AM
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Quote:
Originally Posted by CPMcGraw
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!


As I understand it, B14 was drilled separately, but motors blowing on the drill became a problem. The C5 and B8 used a mandrel, but they had problems with the mandrels breaking or wearing down, or cracks developing in the BP around the mandrel.

I'm looking at a late model FSI F100 and E60, both made in 1989, and they appear to have been drilled.
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  #32  
Old 01-03-2007, 12:47 AM
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Carl,

This is really exciting news.

Please put me down as #1 on the reserve list for 5 packs of each motor and ejection charge.


And as for the original theme of the thread, if Mark is reading, like Craig I'd love to read an in depth article about how Mabel actually worked. Lee Piester's description at Narcon of Centuri's engine works was also really fascinating, as was Carl's description here.

And Carl, I've reconsidered. Make it a case of each.
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  #33  
Old 01-03-2007, 07:43 PM
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Hello Carl,

I noticed there isn't a port burner listed in the 24mm casing sizes. I know you said the 24mm and 29mm motors would be the last to be produced but I was just curious to see if you thought there might not be enough interest for a high thrust 24mm motor?

Since we're bouncing ideas in this new forum, I was thinking along the design lines of a Semroc version of the FSI Mach-1 Dart with a 29mm port burner staged to a 24mm port burner using the LT tubing sizes. Either a slightly larger version using the same FSI fin patterns or a complete make over into a new unique Semroc design. If you thought there would be enough interest I'd be willing to create and submit some designs for your consideration.

Just a thought. What do you think?

.
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  #34  
Old 01-03-2007, 08:43 PM
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One small vote for different colored smoke if feasible. Either boost or delay/tracking.
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  #35  
Old 01-03-2007, 08:55 PM
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Originally Posted by CQBArms
One small vote for different colored smoke if feasible. Either boost or delay/tracking.
That reminds me. Another DECAP is plugged at the top and has 9 seconds of smoke. Used in "extra" engines in clusters.

Colored smoke is something we are looking at. Orange has always been my favorite, but it leaves bad stains from the dye. Manufacturability and repeatability is also a problem. Getting the delay correct with a reasonable amount of smoke is our primary design goal. We used hexachlorethane in the 60's which made volumes of smoke, but it was volatile and the delay time decreased with age. We will probably start out with the a more conventional delay.
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  #36  
Old 01-04-2007, 07:23 AM
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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.


Unless you've got a way to undercut Estes on price on A8-3, B6-4, and C6-5's I think you should concentrate on motors that are different at first. I'll bet a 13mm B would be popular and if you can get a reliable black powder F or an E that has more power than the E9 there will be dancing in the streets. I think someone has mentioned that the cored B's and C's would fill a void.
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  #37  
Old 01-04-2007, 10:05 AM
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Quote:
Originally Posted by billspad
Unless you've got a way to undercut Estes on price on A8-3, B6-4, and C6-5's I think you should concentrate on motors that are different at first. I'll bet a 13mm B would be popular and if you can get a reliable black powder F or an E that has more power than the E9 there will be dancing in the streets. I think someone has mentioned that the cored B's and C's would fill a void.


On the other hand, one of the purported psychological barriers of entry in the hobby industry for small rocket kit manufacturers is the lack of a similarly branded line of motors.
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  #38  
Old 01-04-2007, 11:01 AM
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Quote:
Originally Posted by Royatl
On the other hand, one of the purported psychological barriers of entry in the hobby industry for small rocket kit manufacturers is the lack of a similarly branded line of motors.
That was one of the ideas kicking around in my head a while back, too. That said, given the retailers' propensity for dealing only with distributors and not directly with manufacturers, I doubt bundling motors with kits would get small kit vendors over that barrier. They would still need to play in distribution, and I'm sure the 800-pound gorilla can make things messy there.

But I still like the idea of pooling demand from the varied kit vendors to establish a critical mass of demand for new motors. I think the key is for the kit vendors to invent new designs which would use new, unique motors. For example, vendor X develops a kit which needs 1/2A boosters. Semroc private labels for the vendor who in turn promotes both the kit and the motor. The business is done over the web. Getting it onto store shelves would probably take painful amounts of effort

But the key is that the motor manufacturing risk is shared with other kit vendors.

Doug
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  #39  
Old 01-04-2007, 12:22 PM
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Quote:
Originally Posted by Royatl
On the other hand, one of the purported psychological barriers of entry in the hobby industry for small rocket kit manufacturers is the lack of a similarly branded line of motors.



Doesn't the existence of Semroc , Flis and a bunch of smaller manufacturers disprove that?
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  #40  
Old 01-04-2007, 12:46 PM
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Quote:
Originally Posted by billspad
Unless you've got a way to undercut Estes on price on A8-3, B6-4, and C6-5's I think you should concentrate on motors that are different at first. I'll bet a 13mm B would be popular and if you can get a reliable black powder F or an E that has more power than the E9 there will be dancing in the streets. I think someone has mentioned that the cored B's and C's would fill a void.
We will have to have a complete line, including those popular three. We are not trying to undercut Estes just as we are not trying to undercut them on nose cones or body tubes. We are just trying to fill a much smaller market with a complete line. We are at the mercy right now of Estes and Quest not discontinuing any more engines. Those three primary engines will work with many current kits, but they limit the creativity of designs that need something different.

The 10-18mm engines will be much earlier than the larger engines. Basically, the larger machine would be capitalized from sales from the smaller machine. We have presented the entire proposed family for input and to see if we have missed any holes before we start the EX procedure.
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