A caution about the Estes STM-012

[Bill]

The instructions say to install the aft centering ring 1" from the rear of the motor tube and the mount with the rear ends of the tubes even.

On mine, the aft ring is blocking the very end of the fin slots. The rear face of the aft centering ring is 1" from the end of the motor tube. I will have to trim a bit from the end of the fin tabs.

Perhaps the instructions should say to install the ring 7/8" or even 3/4" from the end of the motor tube.


Bill

[JumpJet]

I took a look at a kit and sure enough I made a mistake when drawing the fins. I neglected to take into account the thickness of the rear centering ring. Dont be allarmed that part of the centering ring can be seen in the fin slot.


Future production runs of this kit will have updated fins. The easiest fix is to modify your fin is shown below. I also noticed that the bottom of the fin over the tube that holds the engine hook in place made contact before the rest of the root of the fin so I took a little more off this area as well.


John Boren

[Bill]

The motor tube is only 3 1/2" long instead of the expected 3 3/4" long. As instructed, an E motor protrudes 1/2" beyond the end of the tube. A motor hook generally needs around an inch or 1 1/4" to easily flex for motor insertion or removal.

If the instructions simply said to glue the aft centering ring 3/4" instead of 1" from the end of the motor tube, then not only will the ring clear the fin slots by a good margin (to allow for some tolerance of individual builders inaccuracies, such as measuring to the front of the ring versus rear or metric unit conversion), but the hook retainer tube is also moved aft, making your other fin tab adjustment unnecessary. I guess the fin cutting is easier to modify than the instructions? A large stack of instructions already printed?


Bill - amateur kit designer

[JumpJet]

A motor hook generally needs around an inch or 1 1/4"


From the end of the nozzle end of the motor to the rear centering ring there is a distance of 1.56" so I guess I met your requirements.

Changing balsa is always easier than changing instructions, plus I needed to shave an extra 10 thousandth’s off the bottom of the fin that makes contact with the tube that holds the engine hook in place.

John Boren

[Randy]

I took a look at a kit and sure enough I made a mistake when drawing the fins. I neglected to take into account the thickness of the rear centering ring. Dont be allarmed that part of the centering ring can be seen in the fin slot.
Future production runs of this kit will have updated fins. The easiest fix is to modify your fin is shown below. I also noticed that the bottom of the fin over the tube that holds the engine hook in place made contact before the rest of the root of the fin so I took a little more off this area as well.
John Boren

AWESOME! John, your presence here and your response to Bill is a perfect example how businesses should work and why YORF is a great place and THE forum for low-midpower rocketry. How great is it to have a consumer and a manufacturer rep speak directly and publicly about an issue and get a quick , honest, constructive response.

I know there are a couple of other suppliers that frequent the forums that would also handle issues this way as well but it's nice to see the main player responding in this manner.

If this were the norm for all businesses how much better would everything be?

It's nice to know this kind of thing still happens. Thanks for making my day!

Randy
www.vernarockets.com

[bigone5500]

Any of you guys get any measurements of the fins for this rocket? I sure would LOVE to have them. I also would like to know the lengths of the body tubes and the motor mount.

Thanks.

[jetlag]

Any of you guys get any measurements of the fins for this rocket? I sure would LOVE to have them. I also would like to know the lengths of the body tubes and the motor mount.

Thanks.

Going to buy one is probably your huckleberry...they are cheap enough.

Allen

[Shreadvector]

http://www.urbandictionary.com/define.php?term=I'm%20your%20huckleberry
That is a bit more obscure to me than "Bob's your uncle".

Going to buy one is probably your huckleberry...they are cheap enough.

Allen

[jetlag]

http://www.urbandictionary.com/define.php?term=I'm%20your%20huckleberry
That is a bit more obscure to me than "Bob's your uncle".

Glad you liked it! :rolleyes:

[bigone5500]

Bah... You're probably right...

But I sure do like scratch building...

Going to buy one is probably your huckleberry...they are cheap enough.

Allen

[jetlag]

Most folks go on and buy the rocket(s) if they are in production. The reasons are many, but suffice to say it is the right thing to do, since the manufacturer went to all the trouble to get the kit out there for us.
Scratch building, at least as I do it, is building models no longer in production.
I'm sure there are other opinions, though...

Allen

[RWmarlow]

+1 on what jetlag said.... currently in production please purchase and enjoy the Manf. product.
My personal take on it is....If it has been 00P and Reissued (by another manf. or the orig producer) i have no problem with a "tribute build"....oh and anything scale is free game....the other note is...with the discount deal at everyone's favorite store for wicker furniture and popurri) an STM-012 Can be had for about 12 bucks

[Doug Sams]

Looking at the Estes STM 012 kit on the Al's Hobby site (http://store.alshobbyshop.com/7221estesstm012.aspx), I considered the cost of cloning this thing. The tubes, rings and fins are pretty cheap for many builders who have accumulated stashes of parts - maybe 3-4 bucks worth of stuff.

If you have such a nosecone in your stash, then that's a big help. Or, if you can turn one, that works, too. But if you have to buy that cone, I can't imagine getting it delivered (mail order) for less than 5-6 bucks.

And you still don't have the decals. That's gonna be another 5-6 bucks (with shipping).

So, we're looking at a total in the range 13-16 dollars, about the same price as you can get it at Hobby Lobby using a 40%-off coupon (assuming they have started carrying it). Even if one gets it mail order and pays an additional 6-8 bucks in shipping, it saves the hassle of ordering parts from multiple vendors and re-rendering decals. (And the 6-8 bucks can be effectively reduced by adding other items to the order.)

The one thing cloners have going for them on this kit is that there are no hard- or impossible-to-clone parts.

But, for the price of the kit, I don't see any advantages to cloning it.

Doug

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[Doug Sams]

I wrote: But, for the price of the kit, I don't see any advantages to cloning it.I should add, for something like this design, I'm usually inspired to change it anyway :) I think it's begging for conversion to 2-stage! (But booster recovery will present some design challenges!)

Doug

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[Bill]

I should add, for something like this design, I'm usually inspired to change it anyway :) I think it's begging for conversion to 2-stage! (But booster recovery will present some design challenges!)


The booster is a bit long for gap staging. Light the second stage with electronics.

Or if you have superhuman gap staging skills, then cluster the booster to get additional ejection charges for recovery.


Bill

[Doug Sams]

The booster is a bit long for gap staging. Light the second stage with electronics.

Or if you have superhuman gap staging skills, then cluster the booster to get additional ejection charges for recovery.Those are the thoughts I had, Bill. Use a cluster with one or two motors ducted to light the sustainer and the remaining motor(s) to eject the booster recovery. Or use electronics.

Doug