exchangable motor mount

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Stewart32

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Hello All,

I would like to be able to exchange various motor mount configurations within the same (model) rocket. For example, swap three 13 mm mounts for a single 18mm or possibly a 24 mm mount. Any thoughts on how to secure the mount within the BT?
Anybody know of any resources on the web?

Thanks y'all.

Stewart
 

wwattles

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I've done this with a moderate amount of success with an Estes Phoenix. I used a long tube coupler with the motor mounts glued to the inside. The tube coupler was friction fit into the inside of the body tube. It works well for motors up to a cluster of 4 Estes F's, but I wouldn't want to go much higher with it.

WW
 

shockwaveriderz

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consider using an extra engine hook on the outside of the model...
Lets assume for illustration puposes you have a 3x 13 motor mount, an 18mm and a 24mm motor mounts..all will go into say a Bt-60 body tube....well obviously the centering rings for all 3 motor tubes will have to be bt-60 size.....use a rear and front one and make each motor mount assembly the same length..

for example 13 mm are 45mm in length, 18 are 70mm in length while a estes D is also 70mm in length....glue a coupler at say 65 mm up into the body tube to act as a forward mount mount engien block for all 3...and just use 70mm tubes for the 3 13mm x 50mm engines instead of shorter ones...
they will all then be 5 mm outside the end of the main bt-60 body tube and you can use a 2.75" engine hook glued to the outside to hold any of the 3 engine mounts in.....or you can use .031 paino wire an dmake your own engine hook

Stewart if you have a hard time visualizing what I am saying, email me and I'll send you back a drawing to make things clear.

good luck
 

shockwaveriderz

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I did a quick and dirty drawing for all to see....

Instead of the thin paper centering rings shown in the drawing you can always replace those with the thicker wound centering rings....

and each motor mount itself can still have its own engine hook(s)
 

Stewart32

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Shockie,

Wattles,

Yes, I thing either method would work, I like the idea of a friction fit "motor can" with individual engine hooks. Now If JFlis will just produce a 3X13mm for the BT55...hmmmmm

Thanks fellas.
 

EMRR

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True Model Rocketry Kits also have their "Quick Change" mounts, which I have had some success and experience with. There was another thread taking about the interchangeable mounts....

See how I use my TMRK one here



Nick
 

Larry

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Stewart,
This is what I did with my Richter Recker. This first picture is of all the componants. The coupler with the plywood ring and T-nut was glued up into the BT so the cluster mount was even with the rear of the BT. The cluster is held in with the threaded rod through the center of the cluster mount. The 24mm mount has the notched top ring which slides up into the coupler. The coupler is setup like the older PML Kwik switch mounts. A picture of that is in the following post
 

Larry

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This is looking at the coupler. The upper ring is where the notched top CR of the motor mount stops. You then turn the mount about a third of a turn and it can't eject the motor mount when the ejection charge fires. So far it works well. The RR main body tube is BT70. The cluster is BT69. There just wasn't much of an option to change mounts in this rocket, but I wanted to try it anyway.......Larry
 

Stewart32

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Larry,

That's a great set up you have there. Took me a few minutes of study to figure out that the coupler accomdates both the triple and single motor mounts. I like the insert and twist mechanism on the single 24 mm, and would like to borrow your idea.

The triangular bit on top...are they structural members?

Thanks guys.
 

Larry

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Stewart,
Your welcome to give it a try. I didn't know if the pictures would show it well enough. The triangular web on top is structural support and glues to the sides of the BT. I just wanted more support for the the T-nut area. Any other questions you may have just email ,or private message me.....Larry
 
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