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CPMcGraw
01-01-2007, 11:22 PM
Here's a topic I think we're all interested in to one degree or another. We've all heard about the famous (or infamous) MABEL and her siblings and decendants. Reading Carl's interview in LAUNCH, we get another glimpse into the background of the equipment itself, when he describes SEMROC's first machine. The mechanism is air-driven, one supposes due to the need to eliminate sparks that might otherwise be created from electric motors.

What else is involved? For example: How do the separate powders get put into the paper cylinder? How do the cylinders move from one step to the next? How are the cylinders fed into the machine? How are the pressing rams powered? Pneumatic or hydraulic? How do you print the various nomenclatures onto the cylinders?

I, for one, would be very interested in knowing this, just for the sake of having a better understanding...

Carl@Semroc
01-02-2007, 11:08 AM
That is a lot of questions!

To listen to Vern (and Gleda) describe the original Mabel was very exciting for me. It was so different from our machine. Vern was a master of fluid logic design. The original and probably its siblings used no electricity at all. It was all hydralic rams and valves. Even the switches were valves.

We started with hydralic and quickly moved to air. The red hydralic stains were a real nuisance, but the real problem was with speed. Air moves much faster than hydralic fluid. When I asked Vern how he moved the ram so fast (to complete one cycle in 5.5 seconds), he almost matter-of-fact said he moved it down until it hit resistance with a high volume, low pressure supply, then switched it over to a low volume, high pressure supply to do the final pack. Once it hit the pre-set pressure, it switched back over to a high volume, low pressure to move the ram back out of the way. THAT is something that I did not think of. Vern was a genius!

I am not sure what the level of interest in actual engine machine design is.

SEL
01-02-2007, 12:33 PM
Here's a topic I think we're all interested in to one degree or another. We've all heard about the famous (or infamous) MABEL and her siblings and decendants. Reading Carl's interview in LAUNCH,...

STOP! When did the new Launch magazine go out? I havn't rceived mine yet. 'Course it'll probably show up today now that I've asked, buit JIC....

Sean

CPMcGraw
01-02-2007, 12:41 PM
That is a lot of questions!

To listen to Vern (and Gleda) describe the original Mabel was very exciting for me. It was so different from our machine. Vern was a master of fluid logic design. The original and probably its siblings used no electricity at all. It was all hydralic rams and valves. Even the switches were valves.

We started with hydralic and quickly moved to air. The red hydralic stains were a real nuisance, but the real problem was with speed. Air moves much faster than hydralic fluid. When I asked Vern how he moved the ram so fast (to complete one cycle in 5.5 seconds), he almost matter-of-fact said he moved it down until it hit resistance with a high volume, low pressure supply, then switched it over to a low volume, high pressure supply to do the final pack. Once it hit the pre-set pressure, it switched back over to a high volume, low pressure to move the ram back out of the way. THAT is something that I did not think of. Vern was a genius!

I am not sure what the level of interest in actual engine machine design is.

I've always had an interest in mechanical design, even as a kid. When I first heard about MABEL it struck a chord, and I have wanted to learn more about how it worked ever since. Now I've learned something about two different machines. Yours was pneumatic, and Vern's was hydraulic.

One day I might surprise you; I might even surprise myself...:eek: :cool: :rolleyes:

CQBArms
01-02-2007, 02:50 PM
Sorry for my ignorance but what brand engines are the Semroc engines?

Carl@Semroc
01-02-2007, 02:56 PM
Sorry for my ignorance but what brand engines are the Semroc engines?They will be Semroc brand. We have been out of production for 36 years.

CQBArms
01-02-2007, 03:46 PM
Ohhh very cool. I learn something new every day. If I might ask, all of these are going to be A-E? hobby motors? Also will there be the "chance" if hobby motors, to get some different colored smoke in either the boost or delay charge?

Eagle3
01-02-2007, 06:52 PM
I'll go ahead and ask first. :D

What engine sizes are you looking to make (13mm, 18mm, 24mm, etc)?

Composite, BP, or both?

Core burners?

Will the emphesis be to fill gaps in existing motor lines or make a complete line?

Some motors that are no longer around that I really miss...

MPC 13mm B4 (awesome awesome little motor!)
Estes 18mm B4-6 (much better sustainer motor than the B6-6)
Estes 24mm D11-9 (another nice sutainer or min dia motor)
and of course......
Estes 18mm B14-anything :)

Carl@Semroc
01-02-2007, 07:15 PM
Here is a preliminary lineup of the sizes we are looking at:Engine Family Portrait (http://www.semroc.com/documents/engine%20family%20portrait.jpg) 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.

Eagle3
01-02-2007, 07:23 PM
Too cool Carl!!!! I thought 29mm BP engines might be too much to ask for. The old Rocketflite 29mm's were a blast. This will make staging MPR a lot of fun!

CQBArms
01-02-2007, 08:05 PM
Now this is a huge step up for contemporary BP engines!

CPMcGraw
01-02-2007, 08:49 PM
...Here is a preliminary lineup...

What body tubes are available for the 15mm and 10mm motors? These look like they could generate some interesting models.

Something I thought about as a possible sideline item -- Pre-packaged deployment charges (not delay chains) for use with electronic triggers, each with specific amounts of pyro, and with two firing ports (one at each end) for redundancy triggering. Not exactly what we'd be using with our smaller models, but possibly for some of those upper-end 29mm birds...

I see the DECAPs used for the 13mm and 10mm motors, but can this be adapted for the 18mm as well? Or does the pressure generated in the 18mm package exceed the limits for whatever adhesive/mechanical fixatives will be used?

Carl@Semroc
01-02-2007, 09:03 PM
What body tubes are available for the 15mm and 10mm motors? These look like they could generate some interesting models. None yet. The 10mm is the minimum allowed in FAI competition. The 15mm is a mid-size for B motors. Just a suggestion of possibility.
Something I thought about as a possible sideline item -- Pre-packaged deployment charges (not delay chains) for use with electronic triggers, each with specific amounts of pyro, and with two firing ports (one at each end) for redundancy triggering. Not exactly what we'd be using with our smaller models, but possibly for some of those upper-end 29mm birds...The Ejection-only DECAP is a pre-packaged deployment charge.

I see the DECAPs used for the 13mm and 10mm motors, but can this be adapted for the 18mm as well? Or does the pressure generated in the 18mm package exceed the limits for whatever adhesive/mechanical fixatives will be used?The 13mm DECAP glues inside an 18mm engine. The 10mm DECAP glues inside a 13mm engine. Probably a potential source of confusion.

The 13mm DECAP (for 18mm standard engines) will probably be the one we do. If it is popular, we might add the 10mm. One of the primary advantages of the DECAP is precision times. The accuracy of a standard engine is only as accurate as how much of the propellant "runs" up around the ram. The DECAP eliminates this variable. Another advantage is the ability to pick in-between times for models that don't fit the 2 second spread.

CPMcGraw
01-02-2007, 09:08 PM
...The Ejection-only DECAP is a pre-packaged deployment charge...

...The 13mm DECAP glues inside an 18mm engine. The 10mm DECAP glues inside a 13mm engine. Probably a potential source of confusion...

Now I understand. Thanks.

One presumes the "ejection-only DECAP" can be fired with an igniter, not just as part of a motor assembly?

A Fish Named Wallyum
01-02-2007, 09:12 PM
What body tubes are available for the 15mm and 10mm motors? These look like they could generate some interesting models.

Something I thought about as a possible sideline item -- Pre-packaged deployment charges (not delay chains) for use with electronic triggers, each with specific amounts of pyro, and with two firing ports (one at each end) for redundancy triggering. Not exactly what we'd be using with our smaller models, but possibly for some of those upper-end 29mm birds...

I see the DECAPs used for the 13mm and 10mm motors, but can this be adapted for the 18mm as well? Or does the pressure generated in the 18mm package exceed the limits for whatever adhesive/mechanical fixatives will be used?

One of the first things I did when stumbling back into the hobby in 2001 was buy a bunch of Apogee cones, rings and tubes. Somewhere in my shop I've got a mess of 10mm tubing that was part of the deal. I was all excited when I got the tubes, but he almost immediately ditched the 10mm motor line, so my excitement was short-lived. Guess I have to dig again. :rolleyes:

Carl@Semroc
01-02-2007, 09:12 PM
One presumes the "ejection-only DECAP" can be fired with an igniter, not just as part of a motor assembly?That is correct. Since BP can not be used loosely in model rockets without a LEUP, there is a demand for a pre-packaged ejection charge in several "sizes" of BP loads.

CPMcGraw
01-02-2007, 09:23 PM
One of the first things I did when stumbling back into the hobby in 2001 was buy a bunch of Apogee cones, rings and tubes. Somewhere in my shop I've got a mess of 10mm tubing that was part of the deal. I was all excited when I got the tubes, but he almost immediately ditched the 10mm motor line, so my excitement was short-lived. Guess I have to dig again. :rolleyes:

Is that what those tubes were? I've got a bunch myself, from the same source. I think I bought at least two bags of tubes a few years ago, before I knew about SEMROC or even BMS. I may have to look at these tubes again for future BARCLONE projects. They might be useful in some smaller "Schoolyard Sounders"...

For Carl: Those Apogee bags were likely filled with Euclid's tubes, so they may still have the mandrels for making them. The last time I checked the Apogee site, like Bill said, I think those tubes had been dropped from the packs (TVM has dropped them; I just looked), but they've been replaced with 29mm tubes.

CPMcGraw
01-02-2007, 09:39 PM
...Another advantage is the ability to pick in-between times for models that don't fit the 2 second spread...

What will be the minimum delay tick? 1 Second or 1/2 Second intervals?

Carl@Semroc
01-02-2007, 09:41 PM
Planned is 1 second to keep inventory down.

Carl@Semroc
01-02-2007, 09:42 PM
We will probably get a slightly smaller BT-4 (.410"ID/.436"OD).

Tim's micros were 10.5mm. We wanted ours to be as small as possible within FAI limits.

Eagle3
01-02-2007, 10:01 PM
Carl, how do you plan to make the core burners?

Carl@Semroc
01-02-2007, 10:08 PM
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.

John Brohm
01-02-2007, 10:26 PM
Here is a preliminary lineup of the sizes we are looking at:Engine Family Portrait (http://www.semroc.com/documents/engine%20family%20portrait.jpg) 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?

snaquin
01-02-2007, 10:39 PM
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.

.

Carl@Semroc
01-02-2007, 10:40 PM
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.

Carl@Semroc
01-02-2007, 10:42 PM
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.

CPMcGraw
01-02-2007, 10:56 PM
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?

Carl@Semroc
01-02-2007, 11:02 PM
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.

CPMcGraw
01-02-2007, 11:13 PM
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!

John Brohm
01-02-2007, 11:19 PM
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?

Royatl
01-02-2007, 11:32 PM
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.

Gus
01-02-2007, 11:47 PM
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. :p


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. :D

snaquin
01-03-2007, 06:43 PM
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?

.

CQBArms
01-03-2007, 07:43 PM
One small vote for different colored smoke if feasible. Either boost or delay/tracking.

Carl@Semroc
01-03-2007, 07:55 PM
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.

billspad
01-04-2007, 06:23 AM
Here is a preliminary lineup of the sizes we are looking at:Engine Family Portrait (http://www.semroc.com/documents/engine%20family%20portrait.jpg) 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.

Royatl
01-04-2007, 09:05 AM
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.

Doug Sams
01-04-2007, 10:01 AM
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

billspad
01-04-2007, 11:22 AM
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?

Carl@Semroc
01-04-2007, 11:46 AM
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.

Royatl
01-04-2007, 11:50 AM
Doesn't the existence of Semroc , Flis and a bunch of smaller manufacturers disprove that?

Not at all. Their existence is owed to the Internet. Would either of them be around if they had to break in to retail the way they did in the 60's and 70's? The internet doesn't eliminate the natural chasm between startup and establishment, but it makes it a lot shallower by granting access to customers beyond retail.

Once I see FlisKits or Semroc in over, say, 50% of the retail places that Estes is at (not counting the Big Boxes, of course), then you might consider it disproved.

Carl@Semroc
01-04-2007, 12:00 PM
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.As long as engines are widely available, I don't think a matching brand is as important as it might have been in the past.

The absence of 1/2A and A boosters is a good example of why there is little new or innovative kits to use low power boosters. The places available to fly two-stage rockets with a minimum of a C6-0 is growing smaller all the time. If the C6 was a C12 or C20, at least you could do low altitude two-stage rockets with heavier designs. That is just my opinion. I always liked two-stage rockets that you could see and recover. I also liked the B14-0 because I could make the rocket a little heavier.

I am not sure if Estes and Quest dropped the small boosters and port engines because of low demand or they dropped them to create low demand. I guess we will be working on finding out which it is.

Royatl
01-04-2007, 12:26 PM
I am not sure if Estes and Quest dropped the small boosters and port engines because of low demand or they dropped them to create low demand. I guess we will be working on finding out which it is.

I think Estes was motivated by reducing cost and simplifying inventory. Quest is probably at the mercy of having to buy large manufacturing lots from overseas (but then, when they *did* have their own machines, they didn't diversify too much).

Still you'd think they'd have heard about our field situation here in the populous east, what with the buildings and trees and the soccer moms and all.

CPMcGraw
01-04-2007, 01:28 PM
...I am not sure if Estes and Quest dropped the small boosters and port engines because of low demand or they dropped them to create low demand. I guess we will be working on finding out which it is.

It's probably a dog-chasing-tail problem, beginning with a lack of design direction toward the small motors. Most of the cataloged designs for small motors seemed to go in the "smaller is better" way of thinking, which leads to models like the Mosquito, Quark, and 220 Swift. How many of these have we ourselves lost after just one flight, even on 1/4A and 1/2A power? Lose enough of them, you start getting tired of losing them, and you stop flying them, and then you stop buying the motors because you've stopped flying them...

I'm really interested in the 13 and 10 mm category for my "Schoolyard Sounders" series. Small field issues hit very close to home for me, and right now it prevents me from enjoying multi-stage designs. Having boosters in these sizes would open up a lot of possibilities.

billspad
01-04-2007, 05:17 PM
Not at all. Their existence is owed to the Internet. Would either of them be around if they had to break in to retail the way they did in the 60's and 70's? The internet doesn't eliminate the natural chasm between startup and establishment, but it makes it a lot shallower by granting access to customers beyond retail.

Once I see FlisKits or Semroc in over, say, 50% of the retail places that Estes is at (not counting the Big Boxes, of course), then you might consider it disproved.

I agree with what you're saying but you're orignal message was:

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.

Clearly entry into the hobby hasn't been a problem. Going mainstream and getting into hobby stores is another thing entirely and you're right about that.

snaquin
01-04-2007, 05:51 PM
We have presented the entire proposed family for input and to see if we have missed any holes before we start the EX procedure.

Carl,

Not sure if you missed my earlier post about a port burner not being included in the proposed 24mm size? Is a high thrust E engine an oversight or left off the proposed list for a reason? Just curious :)

.

Royatl
01-04-2007, 06:39 PM
Clearly entry into the hobby hasn't been a problem. Going mainstream and getting into hobby stores is another thing entirely and you're right about that.

That's the point I was making. The internet-enabled portion of the rocketry hobby is wonderful, but when I go into a mainstream hobby store and I see a store full of planes, trains, and automobiles, while there's like only a shelf with all Estes stuff for the rocket section, you gotta wonder what it's gonna take to go mainstream.

Carl@Semroc
01-04-2007, 06:55 PM
Carl,

Not sure if you missed my earlier post about a port burner not being included in the proposed 24mm size? Is a high thrust E engine an oversight or left off the proposed list for a reason? Just curious :)

.The drawing is not completed yet. There are plans for port burners in all sizes, but I have never made one larger than the 18mm 3/4C19 size. They may not be practical, but I want to keep them on the list until we know.

billspad
01-04-2007, 09:36 PM
That's the point I was making. The internet-enabled portion of the rocketry hobby is wonderful, but when I go into a mainstream hobby store and I see a store full of planes, trains, and automobiles, while there's like only a shelf with all Estes stuff for the rocket section, you gotta wonder what it's gonna take to go mainstream.

I wonder how long mainstream is going to be bricks and mortar. I live about 10 miles north of Boston. There is one hobby store (I'm not counting Michael's) that's reasonably close to me and it doesn't even have a good selection of planes, tranes, and automobiles. I could spend an afternoon driving to NH and back for a slightly better selection or I could just order what I want online. I don't think anything I've ordered from Semroc has taken more than a week. There are others who are also as fast and that's the key. Think about Amazon. Order it on Monday and have it in your hands on Wednesday.

CPMcGraw
01-06-2007, 04:25 PM
Carl,

I don't know if you've already picked out a tube size to use with the 15mm motors, but I came up with this prospective list based on the dimensions of the 13mm ST-5. I'm calling these tubes ST-6, since the OD is around the 0.6" mark. This allows essentially the same amount of slip / play as the ST-5 has with 13mm motor casings.

ID = 15.088 mm (0.594")
OD = 15.750 mm (0.620")
Wall: 0.013" (Same as ST-5)

Semroc ID# Length
ST-6180....18.0"
ST-6120....12.0"
ST-6100....10.0"
ST-690......9.0"
ST-675......7.5"
ST-660......6.0"
ST-650......5.0"
ST-630......3.0"

I tried to pick out a good cross section of lengths for general model building, with the ST-630 as the motor tube.

CPMcGraw
01-06-2007, 07:07 PM
Carl,

Curiosity has killed more cats than I can count, but I can't help myself here... :o

When you insert the ceramic nozzle into the casing, do you start from the top down, or just a quick insertion from the... short end?

And, does the ceramic nozzle have a bulge in the middle, or is it more wedge-shaped?

Carl@Semroc
01-06-2007, 07:25 PM
Carl,

Curiosity has killed more cats than I can count, but I can't help myself here... :o

When you insert the ceramic nozzle into the casing, do you start from the top down, or just a quick insertion from the... short end?

And, does the ceramic nozzle have a bulge in the middle, or is it more wedge-shaped?Everything is packed from the top. A nozzle forming die is at the bottom of the pressure chamber and a tube is inserted over it. The loose clay is measured next and then packed down over the die. The clay nozzle is slightly bigger at the top because as you pack the clay, it expands more nearer the ram. It almost flows like a fluid. By the way, so does the black powder and delay.

CPMcGraw
01-06-2007, 07:31 PM
Everything is packed from the top. A nozzle forming die is at the bottom of the pressure chamber and a tube is inserted over it. The loose clay is measured next and then packed down over the die. The clay nozzle is slightly bigger at the top because as you pack the clay, it expands more nearer the ram. It almost flows like a fluid. By the way, so does the black powder and delay.

So the ceramic is not "heat hardened", but "pressed", similar to a piece of tablet candy? As in several thousand pounds of pressure? This is a "dry" clay with a very low moisture content, yes? The product "fluidizes" as it's pressed.

Carl@Semroc
01-06-2007, 08:27 PM
So the ceramic is not "heat hardened", but "pressed", similar to a piece of tablet candy? As in several thousand pounds of pressure? This is a "dry" clay with a very low moisture content, yes? The product "fluidizes" as it's pressed.It does become "fired ceramic" at ignition!

It is dry ceramic and presses to about 40% of its original volume with 10,000 psi. Does anyone know where Vern got his original "ceramic clay"?

Bazookadale
01-07-2007, 12:16 AM
I think Estes was motivated by reducing cost and simplifying inventory. Quest is probably at the mercy of having to buy large manufacturing lots from overseas (but then, when they *did* have their own machines, they didn't diversify too much).

I've been in manufacturing and sales for over 30 years - inventory is EVIL - but a neccesary evil. It was rumored about 10 years ago that Estes' long range plan was to offer only one delay per size (ie the only C motor would be the C6-5 ect.) which really kills inovative design


Still you'd think they'd have heard about our field situation here in the populous east, what with the buildings and trees and the soccer moms and all.

Don't get me started about soccer moms!

Dale Greene

Gus
01-08-2007, 07:05 PM
Does anyone know where Vern got his original "ceramic clay"?
OK Carl, I give up. :o

And as long as you're answering that one, how about an explanation of how "port burners" got their name. ;)

Carl@Semroc
01-08-2007, 09:22 PM
OK Carl, I give up. :o

And as long as you're answering that one, how about an explanation of how "port burners" got their name. ;)Vern said he got the dust that was left over from a local tombstone engraver and the price was right. Never tried THAT! Tried about everything else.

I first saw Port-Burning (PB) in the 1965 Centuri catalog. They called their engines made on the Coaster machine port or center burning solid propellan grain. Estes, I think, always just said center burning. I did not hear core burning until recently, probably associated with Aerotech.

rocket_james
01-08-2007, 09:24 PM
Ohhh very cool. I learn something new every day. If I might ask, all of these are going to be A-E? hobby motors? Also will there be the "chance" if hobby motors, to get some different colored smoke in either the boost or delay charge?

Now that would be cool! I'm not sure if that wouldn't make tracking more difficult, though. My grandson loves the redline, green gorilla, etc motors. Having that kind of availability during boost in the smaller motors would be very cool, though. I have been asked that question about rocket motors (from people who are unfamiliar with rocketr) on many occasions.
James

rocket_james
01-08-2007, 09:35 PM
As long as engines are widely available, I don't think a matching brand is as important as it might have been in the past.

The absence of 1/2A and A boosters is a good example of why there is little new or innovative kits to use low power boosters. The places available to fly two-stage rockets with a minimum of a C6-0 is growing smaller all the time. If the C6 was a C12 or C20, at least you could do low altitude two-stage rockets with heavier designs. That is just my opinion. I always liked two-stage rockets that you could see and recover. I also liked the B14-0 because I could make the rocket a little heavier.

I am not sure if Estes and Quest dropped the small boosters and port engines because of low demand or they dropped them to create low demand. I guess we will be working on finding out which it is.

Yep to all that! I especially loved the B14 motors.
James

rocket_james
01-08-2007, 09:39 PM
It's probably a dog-chasing-tail problem, beginning with a lack of design direction toward the small motors. Most of the cataloged designs for small motors seemed to go in the "smaller is better" way of thinking, which leads to models like the Mosquito, Quark, and 220 Swift. How many of these have we ourselves lost after just one flight, even on 1/4A and 1/2A power? Lose enough of them, you start getting tired of losing them, and you stop flying them, and then you stop buying the motors because you've stopped flying them...

I'm really interested in the 13 and 10 mm category for my "Schoolyard Sounders" series. Small field issues hit very close to home for me, and right now it prevents me from enjoying multi-stage designs. Having boosters in these sizes would open up a lot of possibilities.

Exactly!
James

foose4string
01-12-2007, 11:01 AM
Whoa, is this cool or what? Sorry, I'm late getting in on this thread, but this changes everything about the hobby as we know it. Great stuff Carl!

Mark+3
01-14-2007, 05:00 AM
We have presented the entire proposed family for input and to see if we have missed any holes before we start the EX procedure.

What is the "EX procedure"?

Royatl
01-14-2007, 12:10 PM
What is the "EX procedure"?

from Info-Central.org...

"The Department of Transportation

The DOT regulates the shipment of hazardous materials, including rocket motors of all types, in interstate commerce. The DOT works on an exemption basis: The way it works is that the shipment of all hazardous materials, including rocket motors, is forbidden, unless an exemption is granted by the DOT. A manufacturer wanting to ship a motor must therefore submit it to DOT, where it is evaluated and an exemption number, or EX number, is given. The EX number is issued in a letter which states how the material is classified, and the rules applicable to its shipment. Manufacturers may ask for additional relief, so that for example the DOT may approve the shipment of a substance normally classified as an explosive as if it were merely a flammable solid, provided specific quantity limits and packaging instructions are met. The typical sport rocketry enthusiast is not likely to run afoul of DOT regulations when driving around with motors in their car trunk, unless they are engaged in transporting experimental motors which have not been issued an EX number.

However, knowledge of the EX number system and the applicable DOT shipment regulations is necessary in order to properly ship motors using the Postal Service, UPS, or other carrier. Rocket motors must never be loaded onto a passenger carrying airliner, either in checked baggage or in carry on luggage. Many motors can be shipped using the Postal Service, provided that the package is properly marked and documented. If you have cause to send a motor back to a manufacturer, call and ask for instructions–many will send shipping materials to you that are designed to keep everyone compliant with the applicable regulations."

ghrocketman
01-21-2007, 11:07 PM
The idea of new BP engines in 13, 18,and 29 mm is absolutely GREAT.
This is something the hobby has needed ever since Estes started discontinuing the less popular "niche" motors such as the B14-x, B4-6, C5-x, B8-x and others.
I think it is GREAT that we will once again see BP 18mm port-burners.
I'll probably order at least 5 paks of each port-burner offered.

Eagle3
01-22-2007, 08:46 AM
...
I'll probably order at least 5 paks of each port-burner offered.

and burn em all in one day! ;)

Gus
01-22-2007, 10:07 AM
and burn em all in one day! ;)
Black powder school yard bowling ball launch? :eek:

bsexton
01-22-2007, 05:44 PM
Here is a preliminary lineup of the sizes we are looking at:Engine Family Portrait (http://www.semroc.com/documents/engine%20family%20portrait.jpg) 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.
Please forgive my ignorance and/or if this has already been answered and I just haven't read far enough, but...

What is "PB" and "EB"? I am assuming "EB" is End Burner...

Ltvscout
01-22-2007, 05:45 PM
Please forgive my ignorance and/or if this has already been answered and I just haven't read far enough, but...

What is "PB" and "EB"? I am assuming "EB" is End Burner...
Correct. PB is Port Burner, like the old B14's, FSI F100's, etc.

bsexton
01-22-2007, 05:51 PM
Correct. PB is Port Burner, like the old B14's, FSI F100's, etc.
So does Port Burner = Core Burner? I don't remember B14's and I never flew any FSI motors...

ghrocketman
01-22-2007, 10:12 PM
Yes, port burner (PB)= Core burner; hi-thrust, short duration, "load-lifting" engines.