The Triton was a misprint. It was correct in the Volume 1, Number 1 issue. When we went to a smaller form factor for the second issue, it slipped by. I think it was corrected later, but all my copies have the wrong data.

I think I was counting blocks on the graph sheets from the test stand to get the NEXT page correct and missed it.

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Carl McLawhorn
NAR#4717 L2
semroc.com

Cut down after they were made...hmmm...Estes could make 1/2A6-2S and 1/2A6-0S "Shorty" motors today.So that material is what enabled you all to re-create your original kits--I understand now. Also, I stand corrected regarding the details of the demise of the company in its original form that I posted above. Carl, you really ought to write a book about the history of Semroc Astronautics! If you have any photographs of these machines (now and perhaps from back then), they would be very interesting pieces of history to include on the Semroc web site.If you happened to "snag" any Bo-Mar Development kits, they would make good "Retro-Repro" model rocket kits.The Black Brant III kit's nose cone was the same one that is used in the "Retro-Repro" Lune R-1 kit, and with the scale documentation from Peter Alway's Rockets of the World...voila! Another "Retro-Repro" kit is born! :-)

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

One more question, Carl (and I apologize for asking so many--I just find the history of you all's company fascinating!): Were the old Semroc parachutes the same design (with the same logo at the apex) as the current 'chutes?

(Also, photographs of the old Semroc items in your one box that escaped the tornado, if placed on the Semroc web site, would make a nice little online "museum" of the company's history!)

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Yes, and so can you

A8-5S, A8-3S, 1/2A6-2S and B6-0S can all be made from 18mm motors. But you need to be careful to get the line square and also take care to not let a stray sawing spark light the top end

Furthermore, you can make ¼A3-3TS, ½A3-2TS, ½A3-4TS, A3-4TS and A10-3TS from T motors. I'm sure you know this, but I state it to illustrate the good number of options you have for making your own ersatz shorties.

There are a couple bits missing such as a ¼A booster which existed long ago as well as a few others, but overall you have a fairly good selection without Estes cutting a single motor


Doug

.

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YORF member #11

B6-2S and B6-4S, too, I think. At least hypothetically. Messing around with BP motors is asking for trouble, though. Estes Industries called their 18mm "shorties" Series III motors. In 1971, they replaced them with the Series IV "Mini-Brute" or 13mm "T" motors that we are all familiar with today. So Estes never stopped making motors in that length (1.75" or 45mm); they simply decreased the diameter. I'm guessing that packing so little propellant into such a thick-walled case was wasteful and inefficient. If I'm not mistaken, Estes did the same thing that Carl described. They packed the regular 70mm long cases for their small motors, and then cut them down. Doing that on a mass production scale created a lot of waste; they were throwing away nearly half of the case for each Series III motor that they made. I suspect that the inner diameter of the 13mm minis is identical or very close to the ID of the 18mm cases that Estes was using at the time. They simply "removed" (figuratively) many layers from the outside diameter because the smaller impulse motors didn't need as much confinement. Producing a motor with a smaller diameter also opened up new design possibilities that weren't possible before, as we saw. Simultaneously with the release of the new motors, Estes introduced the first items in a new line of Mini-Brute kits: the Mosquito, the Screamer and the Mini Bertha.

For a brief period Estes also sold an adapter kit that allowed the new Series IV motors to be used in kits that had been designed for the Series III motors. It was essentially a 13mm engine mount. This could be viewed as an early example of "backward compatibility."

But I digress....

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SAM # 0011

I know that I could "roll my own" (or cut down my own, in this case) Series III motors, but I'd rather buy factory-made, NAR-Certified ones that would be covered by the NAR insurance. However, I'd be just as happy if a lot of the discontinued 13 mm impulse & delay combinations were put back into production, as 13 mm/18 mm adapter mounts (when needed) are common and cheap.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Page 27 - The Old Rocketeer: Engines Full Circle

http://www.ninfinger.org/rockets/Mo...03n09_07-71.pdf

Note that no mention of any Estes mini motors is made in this issue of the magazine (not that Harry would've mentioned them in his article even if he'd known about them, since he was working for MPC). The August issue did have an item in the new products section that said Estes announced them at a trade show in June. The NAR certification list shows the certification of the MPC motors but nothing on the Estes motors.
So it can be assumed that Estes was responding quickly to the MPC motors (MPC ran their first Minijet ad in the June issue, which would've been out late April/early May).
Both Estes and MPC gave everyone at NARAM 13 a pack of their respective mini-motors, but I can't recall if the Estes motors were contest certified for NARAM the way the MPC motors were.

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Roy
nar12605

Actually, I never heard of MPC (or Semroc 1.0) during their lifetimes, and I have only been learning about them since becoming a BAR. I still know very little about them or about most of the other model rocket companies that existed between 1958 and 2004. I knew about Estes and had heard of Centuri, but that was it. From what I have been able to glean, many of them were the originators or earliest proponents of quite a few of the technologies that we all take for granted now. And even now I am still hearing for the very first time of companies that were in business and had that a following at some point during the past 52 years. I'm also still periodically discovering the actual origin of yet another thing that we use all the time.

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SAM # 0011

Another "innovation" (which isn't really that because it started with MMI) that fascinates me is hardwood nose cones. They appeared at the very beginning of the hobby, then were quickly superseded by balsa nose cones, although some MMI Aerobee-Hi kits and their Arcon kit used vinyl nose cones (and some production runs of their Aerobee-Hi kit may even have had hard rubber nose cones).

Then later in the 1960s, small companies like AMROCS (see: http://www.ninfinger.org/rockets/ca...7amrocscat.html ) and Bo-Mar Development Company (see: http://www.ninfinger.org/rockets/ca...69bomarcat.html ) reverted to hardwood nose cones, although some small manufacturers such as Rocket Development Corporation (see: http://www.ninfinger.org/rockets/ca...6/66rdccat.html ) appear to have never discontinued hardwood nose cones. I wonder if safety concerns or cost considerations drove the move away from hardwood nose cones?

Although the NAR Safety Code doesn't specify what *kind* of wood can be used in model rockets, balsa nose cones are more frangible in the event they strike something, their wood may be cheaper to obtain than maple and other hardwoods (although balsa itself is botanically classified as a hardwood!), it is easier to turn nose cones from (and doesn't wear out tooling blades as quickly), and balsa nose cones are much easier to sand-down-to-fit if they fit too tightly in body tubes.

However, hardwood nose cones are less susceptible to "smileys" (gouges of that shape caused by nose cones snapping back after ejection and striking the front edges of body tubes), and their greater weight usually makes nose cone weights unnecessary. Also, screw eyes are less likely to pull free from hardwood nose cones. In addition, they should be easier to sand and seal due to their greater density and more closed grain. Basswood would seem to be a good "intermediate" wood (between balsa and maple) for nose cones when these qualities are desired or needed.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Hardwood nose cones may have been less susceptible to damage by rebound during the recovery system deployment, but that means that they had even more potential to heavily damage any part of the rocket that they struck. A couple of other companies that used hardwood nose cones were Flight Systems, Inc. and Crown Rocket Technologies. It was in the fields of mid-power and early high power rocketry that hardwood nose cones made their last stand. I think that balsa nose cones were originally favored in the early days precisely because of their relative fragility. Pioneers, especially GH Stine, were intent on removing as much of the newly invented model rocket's potential for damage as possible. A stray rocket with a hardwood nose cone has the nearly the same potential for damage as a large caliber bullet. They wanted to design rockets that would disintegrate in the event of a high-speed impact, rather than punching a hole in whatever they struck.

I suspect that it was the advent of injection-molded styrene nose cones that made hardwood nose cones obsolete. Not only were they cheaper and much faster to produce (once a company had made the steep initial investment in the molds), but they had less mass while still retaining a relatively mar-resistant exterior. Switching to plastic also, of course, made it possible to design shapes that weren't possible to execute on a lathe-turned wooden cone. You can still get hardwood nose cones custom made out of nearly any wood available, but no one specifies them anymore as standard equipment in kits or keeps them in stock as a component for scratch-building.

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SAM # 0011