• If you have bought, sold or gained information from our Classifieds, please donate to Rocketry Forum and give back.

    You can become a Supporting Member which comes with a decal or just click here to donate.

RMS-RC™ 18/20 Motor Case

dhbarr

Amateur Professional
TRF Supporter
Joined
Jan 30, 2016
Messages
8,231
Reaction score
2,651
Got one of these hanging around? At the very least I'd like you to weigh it & measure it, but a more permanent arrangement may be preferred :)

Note that my intent is to compare / contrast with an 18/20 and the solid plugged forward closure as well as an epoxied standard 18/20 forward closure.
 

KevinM

Well-Known Member
Joined
Sep 4, 2009
Messages
127
Reaction score
38
I'm not looking to part with my 18/20, so I went for the measurement option.

My standard case weighs in at 11.9g. (Case, fwd closure, aft closure.) Case with a JB-weld plugged fwd closure comes in at 12.4g.

I wasn't aware there was a solid plugged forward closure for this case.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,295
Reaction score
3,179
Location
Pasco, WA
I'm not looking to part with my 18/20, so I went for the measurement option.

My standard case weighs in at 11.9g. (Case, fwd closure, aft closure.) Case with a JB-weld plugged fwd closure comes in at 12.4g.

I wasn't aware there was a solid plugged forward closure for this case.

There is a manufactured plugged closure, its available from Aerotech's online store and at least one dealer ( I just can't remember who).
 

dhbarr

Amateur Professional
TRF Supporter
Joined
Jan 30, 2016
Messages
8,231
Reaction score
2,651
Thanks! So only two measurements away or so.

The RMS-RC 18/20 precedes the current RMS 18/20; the plugged forward is milled out of the same blank as the tube.
 

Tonimus

Well-Known Member
Joined
Jul 8, 2014
Messages
1,511
Reaction score
9
If the RC 18/20 does not have a delay cavity, it should weigh the same without the aft closure as just the case of a regular 18/20 without closures. The aluminum that makes up the threads on the regular case should be enough to compensate for the end of the RC case.
 

dhbarr

Amateur Professional
TRF Supporter
Joined
Jan 30, 2016
Messages
8,231
Reaction score
2,651
If the RC 18/20 does not have a delay cavity, it should weigh the same without the aft closure as just the case of a regular 18/20 without closures. The aluminum that makes up the threads on the regular case should be enough to compensate for the end of the RC case.

The few data sources I've found indicate a slightly thicker, perfectly-flat-inside-and-out north end. It also seems the case walls may in fact be somewhat thinner, which is what I'm trying to determine by weight , o.d., and i.d.

There are no forward threads; it is a unibody bulkhead.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,295
Reaction score
3,179
Location
Pasco, WA
Too bad the AT website doesn't have the external dimension drawings for the RMS RC 18/20 like they do for the RMS 18/20.
 

dhbarr

Amateur Professional
TRF Supporter
Joined
Jan 30, 2016
Messages
8,231
Reaction score
2,651
Too bad the AT website doesn't have the external dimension drawings for the RMS RC 18/20 like they do for the RMS 18/20.

Actually, since the assembly instructions for the old D2-RCT do have some scale drawings in them, it might be possible to get in the right neighborhood. Weight especially might be a SWAG though.

My hunch: the RMS-RC 18/20 is both lighter and shorter in OAL than the modern offerings, both desirable properties for some tiny projects I have in mind.
 

iqsy59

Well-Known Member
Joined
Feb 9, 2012
Messages
937
Reaction score
14
I have both. I will compare them later this evening...

Cheers,
Michael
 

iqsy59

Well-Known Member
Joined
Feb 9, 2012
Messages
937
Reaction score
14
I have both. I will compare them later this evening...

Cheers,
Michael

I wasn't able to find it this evening. I know it is hiding in one of my boxes of hardware! I will keep looking...

Cheers,
Michael
 
Top