Estes Pro Series II cloning part question

[ZoomieG]

Since my return to the hobby a few months ago, I've been contemplating a clone or clones of the Estes Pro Series II rockets that debuted in the 2012 catalog. The Estes website has most of the nose cones, body tubes, and motor mount parts, and fin + centering ring sets are available from several online vendors. The one part that I can't seem to find is called a "green spacer ring" in most of the kits. It was part number 031361 in the first wave of kits (Leviathan, Ventris, Partizon, Argent, & Nike Smoke). I don't know if it's the same dimensions, but a similar ring with part number 031362 is currently available in the Der Big Red Max and Doorknob kits. In all cases, the part is used to space the centering rings on the motor mount tube, and then glued on to one of the rings and the tube.

Here are my questions:
1 - Are the two part numbers dimensionally the same?
2 - Does anyone have a method to replicate or substitute such a ring?
3 - Is it necessary? In other words, can the rings be spaced simply by measured like the Super Big Bertha, and the spacer ring is superfluous?

Thanks in advance for the input!
-zG

 

[user 35280]

Since my return to the hobby a few months ago, I've been contemplating a clone or clones of the Estes Pro Series II rockets that debuted in the 2012 catalog. The Estes website has most of the nose cones, body tubes, and motor mount parts, and fin + centering ring sets are available from several online vendors. The one part that I can't seem to find is called a "green spacer ring" in most of the kits. It was part number 031361 in the first wave of kits (Leviathan, Ventris, Partizon, Argent, & Nike Smoke). I don't know if it's the same dimensions, but a similar ring with part number 031362 is currently available in the Der Big Red Max and Doorknob kits. In all cases, the part is used to space the centering rings on the motor mount tube, and then glued on to one of the rings and the tube.

Here are my questions:
1 - Are the two part numbers dimensionally the same?
2 - Does anyone have a method to replicate or substitute such a ring?
3 - Is it necessary? In other words, can the rings be spaced simply by measured like the Super Big Bertha, and the spacer ring is superfluous?

Thanks in advance for the input!
-zG

Contact Estes customer service I’m sure they could help you with your questions.

 

[Rex R]

Been awhile since I built mine... The ring also checks to see if you read the instructions, I've heard of a number of folks who glued it on the wrong end. Just measure carefully ànd you can do w/o it.

 

[kuririn]

The ring is to make sure the large CRs are perpendicular to the motor tube when glued, and not canted.
Gluing the ring to the end of the tube will strengthen the end of the tube, but IMHO not needed.
Estes - Leviathan (#9700) Gallery | Page 5 | The Rocketry Forum

 

[Scott_650]

If you really want to totally replicate building a PSII kit a piece of T52H coupler could be used in place of the #31360/#31361/#31362 spacer ring - I don’t know how long it should be off the top of my head…

 

[K'Tesh]

What we have here is an apparent mistake in part numbers from Estes... The original PSII kits were being done during the financial crunch in the days leading to the collapse of Estes's previous owner, and it seems that quality control may have slipped. I'm fairly certain that the green spacer rings are all the same (but I don't have physical samples here in China with me to take measurements (and I seem to have missed them on my sims (They were some of my first sims... sorry I missed those parts))).

In looking at the instructions (from their website):
In the Majestic, P/N 031361 is the Engine Block, it does not have the Green Spacer Ring.
The MDRM has a Green Spacer Ring (P/N 031362), but no Engine Block.
The Argent has a Green Spacer Ring (P/N 031361), and an Optional Motor Block (P/N 031362).
The Nike Smoke has a Green Spacer Ring (P/N 031361), and an Optional Motor Block (P/N 031362).
The Ventris has a Green Spacer Ring (P/N 031361), and an Optional Motor Block (P/N 031362).
The Leviathan has a Green Spacer Ring (P/N 031360), and an Optional Motor Block (P/N 031362).
The Panavia has a Green Centering Ring (P/N 031362) (but its function in the instructions matches the instructions of the Green Spacer Rings from the other kits), but no Engine Block.
I couldn't find the instructions for the Sahara.

So, the original PSII kits have Green Spacer Rings that are either P/Ns 031360, 031361, or 031362
The Optional Motor Block is 031361, or 031362

Seeing that the 29mm Motor Retainer Sets are all the same, the Spacer rings are logically the same despite whatever part number Estes gives them (my physical sample from a DBRM right here is .501" long, 1.296" OD, and 1.213" ID.

With the Optional Motor Blocks, the general consensus seems to be to leave them. This opens the kits up to have longer motors than the limited number of motors that Estes had licensed from Aerotech.

 

[ZoomieG]

Thank you everyone for your replies!

@kuririn, I had assumed based on the instructions for the kits that the ring was being used to set spacing, but it totally makes sense that it would ensure a perpendicular joint.

@Scott_650 , I'm not sure a T52H coupler would work. My understanding is that T52 is about the same size as the 29mm motor tube this ring is supposed to fit over. Wouldn't a T52 coupler be smaller than the tube, instead of larger?

@K'Tesh , excellent breakdown of the kits and part numbers. Of note, part number 031360 appears on the Leviathan instructions twice. It is both the motor tube (8" 29mm), and the spacer ring. I am inclined to think this is actually a typo on the Leviathan instruction sheet, as all other 2012 PSII rockets share the same PN for the motor tube, but use 031361 for the ring. I think the spacer ring for Levi should also have been 031361.

Realistically, any of these clones might be a ways off for me. However, after seeing the precise measurements K'Tesh posted, it just occurred to me that I can probably make a CAD file and 3D print this.

It might be a while, but once I get a valid print that matches the original, I'll be sure to post it on the forum.

Thanks again!

 

[K'Tesh]

Thank you everyone for your replies!

@kuririn, I had assumed based on the instructions for the kits that the ring was being used to set spacing, but it totally makes sense that it would ensure a perpendicular joint.

@Scott_650 , I'm not sure a T52H coupler would work. My understanding is that T52 is about the same size as the 29mm motor tube this ring is supposed to fit over. Wouldn't a T52 coupler be smaller than the tube, instead of larger?

@K'Tesh , excellent breakdown of the kits and part numbers. Of note, part number 031360 appears on the Leviathan instructions twice. It is both the motor tube (8" 29mm), and the spacer ring. I am inclined to think this is actually a typo on the Leviathan instruction sheet, as all other 2012 PSII rockets share the same PN for the motor tube, but use 031361 for the ring. I think the spacer ring for Levi should also have been 031361.

Realistically, any of these clones might be a ways off for me. However, after seeing the precise measurements K'Tesh posted, it just occurred to me that I can probably make a CAD file and 3D print this.

It might be a while, but once I get a valid print that matches the original, I'll be sure to post it on the forum.

Thanks again!

Honestly, you don't need the green ring... Gussets would work just fine too, and depending on the size, possibly be quite a bit stronger as well.

 

[Rex R]

I wrapped an index card around the mmt and drew a line around the tube in the proper locations, of course I had some practice with other large rockets

 

[Scott_650]

Oops! As already mentioned by the OP, a T52 coupler is, indeed, too small - it would need to be a T55 coupler. Either way I think K’Tesh and others are right, the green ring really isn’t a needed structural part. Regardless, the original PSII builder kits are pretty solid rockets and worth cloning - good luck!

 

[ZoomieG]

Following up on this thread:

After measuring part number 031362 from a Big Der Red Max kit with a digital caliper, I can report the following:

Internal Diameter is 1.20"
External Diameter is 1.30"
Tube length is 0.5"

Note that the instructions have you "stretch" this part over the nose cone, as out of the box it is too small to fit over the 29mm motor tube, which has an external diameter of 1.210".

As Scott_650 mentioned above, a 1/2" section of T55 coupler would work as a replacement, with it's ID of 1.212".