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UMRS

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Got some old kits that need the ole shorty. I was thinking it would be easier to just cut the ends of the A8-3s off on a tube cutter, rather than try to cut them by hand.

Any thoughts of a prefered method to cut them?

And for all you "uptight by the book people" out there we know its not supposed to happen.
 
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Micromeister

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The only place you can use such a motor would be your own back yard. It's a violation of the Model rocket safety code to alter in any way your model rocket motors.
This is the very reason it's not allow to drill a retainer hole in the unused upper portion of motor casing as a way of retaining the motor in minimum diameter models. Dumb that it's the rule.
a better way is to use an adaptor to fit 13mm motors in the shorty models. that's what I do on my Midget 2 stage. Works just fine:)

If your flying on your own property then i'd suggest [deleted by your friendly moderator]
 
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shreadvector

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My response never appeared. Hmmmm. Glitch already on the New RF?

I stated the obvious to use a 1.75" length of 18mm casing with a mini motor glued or taped inside. Then it would be an almost exact duplicate of the original Shorty motors.

Quest casings are a perfect fit.

Edit; Nevermind. I responded to the duplicate thread that was posted in a duplicate manner on that other forum for olde rockets.

http://forums.rocketshoppe.com/showthread.php?t=4584
 
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UMRS

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its all good fred, thats what were going to do ;)

My response never appeared. Hmmmm. Glitch already on the New RF?

I stated the obvious to use a 1.75" length of 18mm casing with a mini motor glued or taped inside. Then it would be an almost exact duplicate of the original Shorty motors.

Quest casings are a perfect fit.

Edit; Nevermind. I responded to the duplicate thread that was posted in a duplicate manner on that other forum for olde rockets.

http://forums.rocketshoppe.com/showthread.php?t=4584
 

MarkII

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I liked and flew Estes Series III engines back in the late '60's. I put away my rockets "temporarily" in 1971, when shorties were still in production. I was surprised and dismayed when I resumed flying in 2004 and found that these engines were not being made anymore. How was I going to fly the replacements for my beloved Midget and my dearly missed Sprite that I was planning on building if there were no shorties?

I read about trimming the cases of Estes 1/2A, A and B motors, and figured that eventually, that was what I was going to have to do. But this posed a real ethical problem for me, because I was always a firm believer in the Model Rocketry Safety Code. And when I finally joined NAR a couple of years ago, I pledged to uphold that code. What did it mean to be a member of NAR if I wasn't going to follow the Code?

I was "thumbing" through old Estes catalogs online at Ninfinger when it finally dawned on me: Estes Industries never stopped making shorty engines! They continued to produce them all through the '70's, '80's and '90's, and the present-day Estes-Cox Corporation is still cranking out them out by the truckload even today. We have all purchased and flown packs of them, and it's a good bet that almost everyone who reads this post has a stash of them in their engine box.

So why does everyone say that Estes Series III "shorty" engines are out of production? Well, because they are - the older 18mm diameter versions of them, that is. In the early '70's, the Damon-owned Estes Industries introduced a new, updated version of the Series III engines. They reduced the size of the case, making the engines more efficient by trimming away some of their dead mass, and also making the engines more versatile, allowing new rocket designs that were not possible with the old version. They called the new version shorty engines Mini-Brute "T" engines. Yes, that's right - the 13mm mini "T" engines produced by Estes ARE their "Shorty" engines, but in a redesigned case. Estes has been producing mini "T" motors continuously since their introduction in 1971. These are the shorty engines, and they never went OOP.

If you want to build a clone of, say, the Estes Sprite, you can still fly it on a current-production shorty engine - you just have to adapt it to fit the repro Sprite's engine tube. You can fly the sustainer stages of repro (or even original) Midgets and Betas the same way. Although Estes still makes 13mm diameter shorty engines, they currently do not make booster versions, which is truly unfortunate, and also a bit incomprehensible. There are stashes of A3-0T and A10-0T engines here and there in the retail channel, so one can still buy small quantities of them with a little bit of hunting around. They are no longer certified by NAR, but that is apparently due entirely to the fact that they were no longer being produced, and not due to any flaws in the engines themselves. I flew a cloned Mini-Brute Midget with an A3-0T in the booster at an official "Old Motor Test Launch" held by my section a couple of years ago, and it performed beautifully. Which leads to a question: whatever happened to the Old Motor Test Program? Is it still being conducted? Has NAR S&T collected enough data yet to draw any conclusions and make any decisions? If not, then let's set up some more Old Motor Test Launches and generate some more data! In fact, let's generate a lot more data! And let's keep the pressure on Estes to start producing short-length 1/2A and A booster engines again.

Mark \\.
 

gpoehlein

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Mark has a lot of good points, but I thought I would add to it a little bit.

A number of people point out that you can make a quick and dirty adapter by pealing out a layer or two from the inside of a cut off 18mm motor casing and putting the 13mm motor inside. The reason I don't recommend that is weight. Think about this: a 1.75" length of BT-5, three centering rings and a motor hook (which is needed for an adapter) is still lighter than a cut down 18mm case. Add in the weight of the motor and you've got a lot of extra cardboard mass back there that you don't need. And, since the weight is in the back, it is gonna throw the CG off some too. If you build about three adapters, you've got plenty for a launch. They're easy to make too. Give it a try.
 

Gillard

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Estes brought out an adaptor to fit a 13mm T motor that was for use in its shortie motor rockets.

i got a few kits some years back, all of those kits got taken apart for the bits, but i did build one, as i have one old shortie motor rocket.

can't think why i sprayed it orange??

shortie adaptor.JPG
 

Gillard

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i remember why its orange now - having had an adapter spit out the back of a 29mm rocket (29/24 adapter) i remember cursing myself for not having a more vivid colour to aid recovery.

why do Estes have their motors that dull dried grass, dead leaf colour - you think a nice bright colour would be better.
 
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