BT size on Estes Big Daddy

[BKROSNEY]

To all,

I've got an Estes Big Daddy kit that's been sitting in its bag for quite some time. Just didn't want to do a simple 24mm MMT on this thing and have been searching for some inspiration.

Well, I found it. Inspired by JBeau's recent "Interchangeable MMTs" thread and the referral within to OKTurbo's upscale Der Red Max with interchangeable MMT sub-assemblies I've decided to try the interchangeable MMT idea.

The idea will be built around a BT70 BT centered within the Big Daddy body, and interchangeable MMT sub-assemblies based on BT70 CR's (much the same as OKTurbo's Der Red Max).

As I'm putting an order together for BMS I'll probably order the CR's custom cut.

Since the CR's will be custom cut, I might as well get them cut as close as possible.

As far as I can tell, the OD of the Big Daddy is 3" even. But I don't have a set of calipers to measure exactly. The tube appears thicker than the standard Estes BT80 stuff, but not as thick as the LOC tubing.

Does anyone have, or can anyone supply, the exact dimensions of the Big Daddy tubing? OD, ID, etc.

Thanks in advance.

... Bill

 

[rbeckey]

The shoulder diameter on a Bid Daddy NC is 2.93 inches. The tubing is an odd and unique size. You will not find any stock parts for this size except Estes Big Daddy. I believe the OD is 3.0, but I know the NC diameter for certain. That should be good for a diameter on CRs.

 

[shinbone]

Totally Tubular sells the Big Daddy tube. They could probably tell you the precise ID.

 

[SwingWing]

According to Ye Olde Rocket Shoppe, the Big Daddy is made from old North Coast Rocketry parts. They list it as NCR BT-30. The nose cone is a p/n PNC-3000A or NCR-30P2. It is 3" OD. The BT is 3" x 10".


https://www.rocketshoppe.com/info/Estes_Nose_Cone_Reference_sm.pdf Page 10

https://www.estesrockets.com/images/big_daddy_inst.pdf

 

[JBeau]

I may be off base here, and I KNOW I haven't done the research, but if the BT is a standard size, I'd imagine there are MMT kits for almost every size to adapt to that body size.

Wouldn't starting with those kits and adjusting them to make them more amenable to 'interchangeabilitiveness" be a less frustrating route?

 

[Fore Check]

The Big Daddy tube is a non-standard size; larger than a BT80 and smaller than a BT100 (and therefore smaller than a BT101)

Totally Tubular carries this tube, but I forget what the dimensions of it are.


I too had your thought to do an interchangeable motor mount based on a BT70. In fact, I've already purchased the rings for this purpose from BMS. Fits great! Problem is, the order that I put together for those rings was either drawn up on my computer at work at a previous job or on my previous home computer (so I no longer have the measurements....)

 

[BKROSNEY]

Thanks to all who replied....

I dropped an e-mail to Jim at Totally Tubular to see if he could help; hadn't heard back yet.

I also did the online customer inquiry on the Estes web site asking for help as well. Within 2 hours I had an e-mail response from Christine, who responded that the ID was 2.930.

Wow... great customer service from Estes. Kudo's to them!!!

... Bill