CTI Cesaroni Technology

tbonerocketeer said:

That one I don't know completely. I know they are turned on the lathe but I don't know when the thrust rings get welded on. Did you see the very small evidence of the weld?

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I didn't, but I didn't look for it. I will sometime. When I tried to imagine how they were manufactured I thought they might be swaged larger then machined, but welding on a collar would certainly work. Once welded it's still one piece. The benefit of an integral thrust ring remains.

crossfire said:

Chris
If they are welded on? I would not think they would come loose. I have never seen one that did but have heard of it.

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I've never heard of the thrust ring on a CTI case coming loose, but a bad Cato could separate the case at any point. Maybe that's what happened. The threads for the aft closure are inside the end of the case and they are very sharp. I've cut myself on them a couple times. If they didn't properly radius the thread-cutting tool they may have left a stress-riser on the inside of the threads which could result in failure there.

Steve Shannon said:

I didn't, but I didn't look for it. I will sometime. When I tried to imagine how they were manufactured I thought they might be swaged larger then machined, but welding on a collar would certainly work. Once welded it's still one piece. The benefit of an integral thrust ring remains.

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I seem to remember looking at one and seeing 4 small dots that looked like welds.

tbonerocketeer said:

I seem to remember looking at one and seeing 4 small dots that looked like welds.

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That would change things. I was imagining a socket weld.



[emoji1010] Steve Shannon, L3CC [emoji1010]

They are actually glued in place. No welds, just adhesive

Steve Shannon said:

Having the thrust ring built into the case rather than the aft closure was always a superior method as far as I was concerned. If the aft closure is your thrust ring and you have an aft closure failure, your motor casing shoots up through your rocket, destroying your electronics and parachutes. If the thrust ring is integral to the case, then the aft closure simply shoots downward and the entire rocket goes upward.

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I don't think I've ever seen a big casing (CTI or otherwise) after an cato, but it makes me wonder "how" a Pro75/98 Gen1 casing would fail. If the casing itself fails (as opposed to the nozzle), I don't think the integral thrust ring would help. Compared to AT, the Pro75/98 Gen1 HW has really strong threads, so they will probably not slip out. The only thing that prevents a scary radial cato is the reduction in wall thickness at and just inside of the threads. If the casing fails, I'd expect the end of the casing with the threads to be ripped of. Also, the pressure is higher at the forward end of the motor, so the forward end would probably let go first.
https://www.pro38.com/pdfs/Pro98_notes_V1.6.pdf
Again, I have no experience with relevant catos, this is only based on observations of the casing geometry. It would be interesting to learn about how typical scenarios look like.

On a personal note, I'm happy that CTI ditched the integral thrust ring. It opens certain design possibilities (e.g. fin can sliding over from the back, held in place by the tail cone closure) without taking much away.

Reinhard

The CTI Gen 1 ring is glued into place with a close fit. Some rings were coming loose after 20+ flights, is what I heard. Also, the deeper/stronger ACME-like threads gave a weak point just above the threads inside. I only got 4 flights on my Gen1 case before other non-motor-related circumstances buried it.

The CTI Gen 2 case has shallower threads, slightly different from AT's. I initially had the wrong closure for the Pro98XL Gen2 case and noticed that it was for the AT-compatible version of the CTI reload. Got about 4 thread in and stopped. AMW sent the correct closures and it's all good. Yet to be flown.

For my 6" P casing, I JBWelded a thrust ring on. It also provides more beef for my bolted closure.

I can't see a weld or glue joint on mine. The larger diameter thrust ring has a finish that looks like it was drawn over mandrel. The remainder of the case has been turned to a final diameter.



[emoji1010] Steve Shannon, L3CC [emoji1010]

Another angle


[emoji1010] Steve Shannon, L3CC [emoji1010]

I just talked to WM on Sat. about this. He said they were glued on.

Interesting; did he mention the glue type?


[emoji1010] Steve Shannon, L3CC [emoji1010]

Steve No he didn't say the glue type. Tim said he has only seen one come loose.

Thanks!


[emoji1010] Steve Shannon, L3CC [emoji1010]

Is there a recommendation for treating 38mm cases that have lost patches of the paint?

SpaceManMat said:

Is there a recommendation for treating 38mm cases that have lost patches of the paint?

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Send them to me for proper disposal

SpaceManMat said:

Is there a recommendation for treating 38mm cases that have lost patches of the paint?

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Paint? All my cases are hard anodized silver grey, no paint.

Pretty sure he's talking about the older cases that were silk screened with the Pro38 logo and also the case size. All line have worn off also.

As a side note, I once used some Hoppes gun cleaner (cuts carbon build up like crazy!) on a case I purchased used, and it ate all the printing off of the sticker. Does anyone really care about the stickers? How careful should I be about that?

I take the stickers fully off so they don't leave glue inside my MMT.

DavieRockets said:

Paint? All my cases are hard anodized silver grey, no paint.

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Let me rephrase that, and I think I know the answer now...

Is there any recommended treatment for 38mm cases that have lost some of their anodizing?

Apart from giving them away free to members of the lunatic fringe?

SpaceManMat said:

Let me rephrase that, and I think I know the answer now...

Is there any recommended treatment for 38mm cases that have lost some of their anodizing?

Apart from giving them away free to members of the lunatic fringe?

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Just fly it.

Anyone know what the threading on the plugged 54mm closures are?

1/4-20

Tony

I'm a BAR and getting started with MPR. I live in Mobile, AL, and I'm wondering if there are preferred online vendors for CTI 29mm reloads. I already purchased the Pro29 starter kit from an online vendor in NY, I could use him for the reloads as well, I'm just wondering if there are preferred vendors.

TangoJuliet said:

I'm a BAR and getting started with MPR. I live in Mobile, AL, and I'm wondering if there are preferred online vendors for CTI 29mm reloads. I already purchased the Pro29 starter kit from an online vendor in NY, I could use him for the reloads as well, I'm just wondering if there are preferred vendors.

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Here are a few:

Chris Rocket Supplies
Wildman
AMW Pro-X

Thanks Tim. Now I need to research the thrust curves so I can cross reference the listed Aerotech motors in the instruction manual of my NCR Laserhawk with the corresponding CTI motors.

Thanks Tony

TangoJuliet said:

I'm a BAR and getting started with MPR. I live in Mobile, AL, and I'm wondering if there are preferred online vendors for CTI 29mm reloads. I already purchased the Pro29 starter kit from an online vendor in NY, I could use him for the reloads as well, I'm just wondering if there are preferred vendors.

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Are you planning to fly with us at SEARS 572? I am the on site vendor there.

I don't know anything about it.

TangoJuliet said:

Thanks Tim. Now I need to research the thrust curves so I can cross reference the listed Aerotech motors in the instruction manual of my NCR Laserhawk with the corresponding CTI motors.

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Check out Thrustcurve.org.