Noob question about Cesaroni Motor casings...

[Ccolvin968]

So I was just told that I need a rear closure for my motor.
I was under the impression that the Cesaroni casings came tapered so you did not have to have a rear closure.
Or am I just at the wrong side and the rear closure holds the reload in the casing?
Thanks for putting up with these questions!

 

[75Grandville]

Depends on the size. For 38mm, the rear closure is part of the reload kit. For 24 and 29mm, a separate rear closure is required. For 75 and 98mm, forward and rear closures are required. I think 54mm are like 29 and 24, but don't know for sure.

Edit: Just read some of your other posts. 29mm rear closure looks like this:

(courtesy of Apogee Rockets)

When I got my L1, CTI had a certification special, where you bought the reload and the casing was free (or something like that). Check with your local vendor. Also, you may want to consider getting a couple of spacers, a 3 gr. and a 6 gr. case, which will let you fly any CTI 29mm reload except the 6XL.

 

[Titan II]

See their website at pro38.com. The directions and the hardware section for each size is very detailed. It actually is a really comprehensive website for their products. To add to Bill's response above, the 54 needs a rear.

 

[Ccolvin968]

Grandville, thanks for the info! I have a 38mm reload kit already, but my club president just informed me of the same deal. It's still going on. It's an awesome deal!
I already have the 38mm kit that is 4 grain and 6 grain that came with two spacers so it's pretty awesome. Titan, I'm checking out the website now. Thanks for the link!

 

[djs]

Grandville, thanks for the info! I have a 38mm reload kit already, but my club president just informed me of the same deal. It's still going on. It's an awesome deal!
I already have the 38mm kit that is 4 grain and 6 grain that came with two spacers so it's pretty awesome. Titan, I'm checking out the website now. Thanks for the link!

I'm assuming you mean the 3 and 6 grain cases, as those with the spacers would cover all of the CTI loads in 38mm, except for the 6xl ones. Make sure you also get the DAT (delay adapter tool) as well!

 

[Ccolvin968]

Yes, sorry. 3 and 6 grain. I got the DAT as well!

 

[Titan II]

Use this or something similar. Spray it into the case before installing the load. Some people complain about the 38 mm design. There is absolutely nothing wrong with the design. With lubrication, the loads slide in and out easily....and they screw in easily. Any cross threading is clearly the operators fault and is easily avoided.

 

[Ccolvin968]

Good to know. Thanks for that bit of advice.

Also, is there a difference between the 29mm H123-SK-(delay) and the 38mm H123-(delay)?
Do the letters indicate something that the 38mm motor lacks?

I'm going to be using a 29mm motor with an adapter to fit my 38mm Aero Pack retainer for a couple launches,
(view other post about stepping down from 38 to 29) and I have run into the apparently same motor with lower impulse and about 600ft. less altitude.
Just a little confused is all.

 

[djs]

Good to know. Thanks for that bit of advice.

Also, is there a difference between the 29mm H123-SK-(delay) and the 38mm H123-(delay)?
Do the letters indicate something that the 38mm motor lacks?.

Different total newtons- 176 vs. 232- which is why you'll get less altitude on the 29mm. Same propellant type, but different grain configuration and size.

 

[Ccolvin968]

I get it now!
Thanks for that bit of info djs!

 

[Bat-mite]

A piece of dowel will help you get the burnt liner out after recovery. Always use grease (as suggested above) and then what I do is stick the dowel on the forward end, invert it, and pull down on the casing with both hands. Comes right out.

With bigger motors (like 75 mm and 98 mm), a piece of PVC and a hammer are often necessary.

 

[cerving]

The first CTI motors I ever got were Pro 29's with a threaded rear closure, so when I went to get the Pro 38's I was puzzled that there was no rear closure. Once I saw a picture of the loads with the closure built into the nozzle, it was pretty clear. Interesting that they have not done that with any of the other sizes... 24/29 would work I would imagine, but my guess is that 54 and above the plastic closures are just not strong enough. BTW, the 75 and 98 cases require both front and rear threaded closures (they're not rolled over in the front like the 24/29/38/54's), and there are some Aerotech loads that are cross-certified for the CTI hardware (and vice-versa).

 

[mccordmw]

I have some CTI 54 mm cases. Those do require a separate closure.

https://www.apogeerockets.com/Rocket_Motors/Cesaroni_Casings/54mm_Closures

 

[Cabernut]

From the Coast Rocketry website:

Motor Type 137G60-12A is: 137 = Total Impulse in Newton-seconds; G = NAR motor designation; 60 = Average Thrust in Newtons: -12A = Maximum Adjustable Delay time in seconds.

Propellant type is designated by the letter codes. For example:
CL = Classic
SK = Skidmark
RL = Redline

Here is a description of the propellant types from CTI's site:
https://www.pro38.com/propellant.php

 

[Ccolvin968]

Cabernut, that was nice and simple. Thanks!