fitting Aerotech motor cases into 29mm motor mounts

[AcadiaRockets]

Ok, here goes.
I am excited to receive my Wildman 2.6 V2 and 2.1 Eagle Claw both of which have the 29mm boat tails because given the option of build a rocket with a boat tail or not a boat tail, always go boat tail, because its the coolest.
Now these rockets and their boat tails come with the metal retainer with a snap ring. All cool so far. But. None of the 29mm Aerotech cases with the knurled after retainer fit.
Is this true? Am I missing something?
The exception is single use 29 motors fit - check. And the AT 29 / 40-120 hobby line case fits as its the odd one out with a different aft closure ( not knurled)
Before someone says it, I did reach out to Tim. I spoke with Jackie and Tim is traveling. I am sure he knows but I thought I would check here too. I did some searching the forum and other and could not find this addressed.
thanks.

 

[tim cubbedge]

You can probably get away with friction fit or a wrap of aluminum tape on aft end

 

[jmasterj]

So the retainer's ID is too small to fit the 29mm HP aft closure?

I've used Giant Leap Slimline retainers with AT 29mm HP RMS motors. They look similar in style to the pictured retainer.

Not a dumb or embarrassing question, by the way.

 

[StreuB1]

What aspect does not fit? The diameter or the overall length of the knurled thrust ring end closure?

Edit: Sorry, just looked closer at the pics. It is the diameter that does not fit inside the retainer housing.

Do you have calipers that would allow you to measure the OD of your end closures?

I have mine here and I am measuring the 29/40-120 closure to be 1.226"Dia x 0.250"L and the 29mm HP closure to be 1.265"Dia x 0.367"L

Quite a dramatic difference between the two and the difference in the OAL of the shoulder would dramatically affect the location of the snap ring. Not to mention the 40 thou difference in diameters, which is what is causing your issues.

It seems like an Aeropack might be more suited for this.

 

[AcadiaRockets]

Well at least I wasn't completely missing something. I haven't attached the mount to the FG tube yet so the depth of the thrust ring (or any thrust ring) is not a factor its that width of the knurled aft closure on the 29mm Aerotech line cases.
Does anyone have this same retainer and perhaps 29mm cases from other manufacturers to see if its just an Aerotech problem?
I don't think I would go the screw on motor retainer direction as that would take away from the previously mentioned cool boat tail profile.
I "can" or "could" run only the hobby line Aerotech g motors in these rockets if that's all they can fit. That would be too bad. OR fit Cesaroni cases in there (if they fit) we don't know yet?
I am sure Tim will weigh in at some point too with answers good or bad. @WILDMANRS

 

[tsmith1315]

Who makes that retainer?

 

[jmasterj]

Pro29 closure is 1.25" OD per the dimensional drawing.

I would still recommend a GLR Slimline as the solution, but then you have to spend more money.

 

[Titan II]

Friction fit

 

[DabCat]

I have the same rocket, which I bought a few years ago. I just checked and mine has the same issue.

 

[tim cubbedge]

Who makes that retainer?

It’s custom made by Wildman. It comes with the kits he’s questioning. I had same rockets years ago.

 

[StreuB1]

If you buy another AT 29mm HP end closure, it could be modified to turn down the knurling and mill a cross slot in it to match the hobby-line closure. Easy machining to do which I am sure many would be willing to do for a small sum. Myself included.

 

[AcadiaRockets]

If you buy another AT 29mm HP end closure, it could be modified to turn down the knurling and mill a cross slot in it to make the hobby-line closure. Easy machining to do which many I am sure many would be willing to do for a small sum. Myself included.

Well that IS an interesting offer. I may just take you up on that. I am curious to see what Tims take will be on all this. How do I tag other members on the forum?

 

[tim cubbedge]

Here’s a build thread on same V2. Might help.
https://www.rocketryforum.com/threads/wildman-v2-sport-build-thread-directions-preview.70343/

 

[AcadiaRockets]

Here’s a build thread on same V2. Might help.
https://www.rocketryforum.com/threads/wildman-v2-sport-build-thread-directions-preview.70343/

read that last November before I bought it at black Friday. It was an inspiration!

 

[AcadiaRockets]

I have the same rocket, which I bought a few years ago. I just checked and mine has the same issue.
View attachment 513432View attachment 513433

what motors have you run it in the past?

 

[DabCat]

what motors have you run it in the past?

Actually... I have not flown it yet. It's sat unfinished on the workbench for a couple years now. Only step left is painting. I originally planned to fly it on some of the longer 29s but apparently I may be limited to the hobbyline reloads.

 

[WILDMANRS]

Unfortunately the retainer is made to fit the MMT and all other closures fit except the AT high power . I know we have ground down the OD of the closure to make it fit.

 

[AcadiaRockets]

Unfortunately the retainer is made to fit the MMT and all other closures fit except the AT high power . I know we have ground down the OD of the closure to make it fit.

Thanks Tim! I knew you would know. I think I will do exactly that. I have both an Eagle Claw and a V2 so I will get a second aft closure and take the grinder to it. That will give me some flexibility on motor choices.
I am just glad to know that was what it was and I wasn't missing something. I appreciate closure (no pun intended) to the mystery.
Thanks everyone who helped troubleshoot.

 

[AcadiaRockets]

UPDATE! So thanks for all the help and thoughts. Thanks to StreuB1 for suggesting modifying it. And to Tim for making cool rockets with cool boat tails with cool retainers.
It wasn't off by much in the diameter. I took some 80 grit paper and just turned the closure inside the sandpaper for 5 minutes and it brought it within tolerances to slide inside the retainer. The depth was a little more material and per StrreuB1s caliper it needed to be 0.250"L and was 0.367"L.
Without a machine shop I just used the orbital sander with 60 grit and took off enough material until it matched the 40-120 closure and single use motor rims. Now I can JB weld the boat tail retainer onto the red fiberglass motor mount and all three motors are to the same specs.