CTI Discussion Thread

Zman1961

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I had a similar occurrence with 54mm two grain J280. The flight was successful. When I went to clean out the casing the motor remnants were fused to the inside of the casing. After much careful but forceful coaxing, the liner came out, but part of it remained stuck to the casing. A soak overnight in soapy water enabled the complete cleanup, but revealed a slightly discolored and slightly raised area the size of a kidney bean on the case. This was at the aft grain, not the forward closure. My vendor suggested not using it anymore, we took pictures (at the next launch) and submitted the claim the CTI, and they approved it. It took until the beginning of this season to get the replacement casing, so about ten months. Anecdotally, there were two other CTI casing claims filed at the same time as mine, both were 5 and 6 grain 38mm casings that had completely burned through and taken the fin cans with them, so these also were aft-end burn-throughs. Bottom line - the old case I have is not in bad shape, but people with more experience than me agreed it should not be used again. Why risk $300-$400 worth of rocket on a $60 case?
 

gdjsky01

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Can I use an MJG or BlackSky HiRi (remember them?) instead of the supplied starter for an I223SK? This is a 4 grain 38mm load. I kinda destroyed the supplied one... stepped on it... :angiefavorite:
 

boatgeek

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Can I use an MJG or BlackSky HiRi (remember them?) instead of the supplied starter for an I223SK? This is a 4 grain 38mm load. I kinda destroyed the supplied one... stepped on it... :angiefavorite:
I've used MJG ematches interchangeably with CTI ones for any motor that has the ignition pellet. I'm sure the I223 is fine, but confirm that the head of the ematch fits through the nozzle throat before you get to the pad.
 

gdjsky01

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I've used MJG ematches interchangeably with CTI ones for any motor that has the ignition pellet. I'm sure the I223 is fine, but confirm that the head of the ematch fits through the nozzle throat before you get to the pad.
Thank you!

One more question... if I may.....
If it did not fit, is it okay to use a standard starter such as the Firestarter FS-12 (if you remember Firestarter) dipped in Magnalite? These are very very thin standard composite starters. For that matter I have the 3mm MJG 'black powder' starters which I am sure will fit. Just not sure there is enough ummph to light the pellet.
 

boatgeek

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Thank you!

One more question... if I may.....
If it did not fit, is it okay to use a standard starter such as the Firestarter FS-12 (if you remember Firestarter) dipped in Magnalite? These are very very thin standard composite starters. For that matter I have the 3mm MJG 'black powder' starters which I am sure will fit. Just not sure there is enough ummph to light the pellet.
I don't remember Firestarters, but I've used Firstfire starters in the appropriate size range as well (Firstfire Mini for F and G motors, etc.). I would expect that a dipped starter would be fine for these as well. The 3mm starters are almost certainly enough oomph, but you could also dip it in Duco cement (or silver Testor's paint) and then BP if you want to make absolutely sure.
 

Zman1961

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I have used a starter called the "Slim Gem" on 38mm motors such as was mentioned above, they pack a good punch. I get them from my on-site vendor. Never had a misfire or chuf with these.
 

gdjsky01

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I have a few Quickburst starters. But IIRC they are a pain to use. You have to peel off the outside ???
I think I have my answer. I can use an e-match like the MJGs or a slim 'normal' starter. Thanks. Unless CTI
chimes it, or someone tells me they had a bad experience, I'll go with that. Thank you
 

jahall4

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FWIW, every time I've had a forward burnthrough the case has been obviously bubbled on the outside. This one looks OK to me, it would be interesting to see what the forward closure and liner looked like.

If I tossed every case that had any kind of cosmetic damage inside, I'm not sure how many I would have left. :)

Hi Mike, The entire reload is pictured above in this thread along side the first reload fired in this same case.
 

Racingdrum

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I originally posted as its thread but was told to post here:

I have a Cesaroni J140P that I'm going to use for an L2 launch. I have a couple of questions about this motor that anyone with experience will have an easy time answering:

1) There is a gap inside the motor grain housing; the motor grain does not seat flush against the nozzle and plug. When fully assembled, I can shake the motor and hear the grain banging around. Is this normal?

Also, it appears from the assembly instructions that the nozzle is supposed attached to the grain housing, though mine is not. It's loose, and even fits loosely into the grain housing tube. It also looks like there's dried adhesive on the coupling end, which you can see in the attached photo. I haven't used the Pro54 stuff before, so I'm not sure if this is normal either.

2) The plug has a threaded section with an attached screw. Has anyone used this to secure an eyebolt for affixing their shock cord? This is where I had planned to mount the shock cord, but the strength of the tiny threaded section seems dubious at best.

If the eyebolt on the motor doesn't work out, I'll probably fix some sort of fiberglass bulkhead inside the fin tube with epoxy and thread my shock cord through that. Kind of an oversight but oh well.

Thanks in advance for offering any advice. Let me know if I need to clarify anything.
 

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jahall4

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I originally posted as its thread but was told to post here:

I have a Cesaroni J140P that I'm going to use for an L2 launch. I have a couple of questions about this motor that anyone with experience will have an easy time answering:

1) There is a gap inside the motor grain housing; the motor grain does not seat flush against the nozzle and plug. When fully assembled, I can shake the motor and hear the grain banging around. Is this normal?

Also, it appears from the assembly instructions that the nozzle is supposed attached to the grain housing, though mine is not. It's loose, and even fits loosely into the grain housing tube. It also looks like there's dried adhesive on the coupling end, which you can see in the attached photo. I haven't used the Pro54 stuff before, so I'm not sure if this is normal either.

2) The plug has a threaded section with an attached screw. Has anyone used this to secure an eyebolt for affixing their shock cord? This is where I had planned to mount the shock cord, but the strength of the tiny threaded section seems dubious at best.

If the eyebolt on the motor doesn't work out, I'll probably fix some sort of fiberglass bulkhead inside the fin tube with epoxy and thread my shock cord through that. Kind of an oversight but oh well.

Thanks in advance for offering any advice. Let me know if I need to clarify anything.

Hello,

A Plugged 3G reload is and odd beast. To your #1) I never had assembly of a 54mm CTI result in a "gap". If the fore and aft closure are not seated inside the liner and held there compressed by the case retainer ring, "bad" things will like happen particularly in long burns that are notorious for liner "burn thru". Sometime CTI will "glue" the nozzles to the liners and they come loose that is probably what happened in this case. I'd touch base with your dealer.
 

jd2cylman

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I originally posted as its thread but was told to post here:

I have a Cesaroni J140P that I'm going to use for an L2 launch. I have a couple of questions about this motor that anyone with experience will have an easy time answering:

1) There is a gap inside the motor grain housing; the motor grain does not seat flush against the nozzle and plug. When fully assembled, I can shake the motor and hear the grain banging around. Is this normal?

Also, it appears from the assembly instructions that the nozzle is supposed attached to the grain housing, though mine is not. It's loose, and even fits loosely into the grain housing tube. It also looks like there's dried adhesive on the coupling end, which you can see in the attached photo. I haven't used the Pro54 stuff before, so I'm not sure if this is normal either.

2) The plug has a threaded section with an attached screw. Has anyone used this to secure an eyebolt for affixing their shock cord? This is where I had planned to mount the shock cord, but the strength of the tiny threaded section seems dubious at best.

If the eyebolt on the motor doesn't work out, I'll probably fix some sort of fiberglass bulkhead inside the fin tube with epoxy and thread my shock cord through that. Kind of an oversight but oh well.

Thanks in advance for offering any advice. Let me know if I need to clarify anything.

Are you using the 3 grain case? Or a 4 grain case? If you're using a four grain case, you need a grain spacer. Motor grains can have a little play inside the liner, but the liner should be tight in the case.
More pictures can help us determine your best coarse of action. Or at the launch, consult with your motor vendor.
 

Racingdrum

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Are you using the 3 grain case? Or a 4 grain case? If you're using a four grain case, you need a grain spacer. Motor grains can have a little play inside the liner, but the liner should be tight in the case.
More pictures can help us determine your best coarse of action. Or at the launch, consult with your motor vendor.
I am using a 3G case and a 3G reload. The play is inside the liner, and the liner is held tight in the case by the aft closure. Is there anything in particular you'd like to see a picture of?
 

LithosphereRocketry

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I am using a 3G case and a 3G reload. The play is inside the liner, and the liner is held tight in the case by the aft closure. Is there anything in particular you'd like to see a picture of?
As I understand, it's fairly normal for the grains to be slightly loose in the liner so long as both closures are firmly seated. Is that what you're seeing?
 

Racingdrum

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As I understand, it's fairly normal for the grains to be slightly loose in the liner so long as both closures are firmly seated. Is that what you're seeing?
Yes. The grain (it's one long continuous grain) is loose enough in the liner to where it moves back a forth slightly if you shake it.

As long as it's not totally abnormal I'll launch it. Thanks for the help.
 

sharkbait

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Yes. The grain (it's one long continuous grain) is loose enough in the liner to where it moves back a forth slightly if you shake it.

As long as it's not totally abnormal I'll launch it. Thanks for the help.
I have flown several J-140’s in my saucers, been 6-7 years ago though. A little play is ok, you can also add a spacer O-ring at the forward end if you want. There is a very slight chance that your liner was cut a little too long, make sure you are getting full engagement of the rear threaded closure ring, if so you are good to go, if not then your liner is a little long. I would go ahead and glue the nozzle and the forward after you check everything again.

It’s a moon burner, that’s why it’s one single grain and why you get 8.5 seconds of burn time
 

Racingdrum

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I have flown several J-140’s in my saucers, been 6-7 years ago though. A little play is ok, you can also add a spacer O-ring at the forward end if you want. There is a very slight chance that your liner was cut a little too long, make sure you are getting full engagement of the rear threaded closure ring, if so you are good to go, if not then your liner is a little long. I would go ahead and glue the nozzle and the forward after you check everything again.

It’s a moon burner, that’s why it’s one single grain and why you get 8.5 seconds of burn time
I actually thought about taking the liner to a belt sander to shorten it a hair, though from the responses it seems to not be a huge deal.

I'm guessing all the J140s you've flown had their nozzles affixed into the liner? If so I'll super glue that sucker in.
 

Reinhard

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2) The plug has a threaded section with an attached screw. Has anyone used this to secure an eyebolt for affixing their shock cord? This is where I had planned to mount the shock cord, but the strength of the tiny threaded section seems dubious at best.
It's been a while, but if I remember Jeroen correctly, the threaded insert is only intended for motor retention and not as a hard point for the recovery harness.

Reinhard
 

mikec

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2) The plug has a threaded section with an attached screw. Has anyone used this to secure an eyebolt for affixing their shock cord?
Yes, and it's worked fine. Most of the load on a threaded joint is carried by the first 2-3 threads. But I'm not sure what CTI's official position is. All I know is that they say the Aeropack MD retainer adapter that taps into the plastic is only for retention, but that's something different.
 

JackC

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I had an M1101 reload bought last year that took an hour+ of sanding before it fit my Aerotech case. Same case, two Aerotech reloads, fit perfectly normally. Something up with CTI 75mm liner tolerances, no question.
Well, I had the same issue with an M1101 I purchased on 07/22. I cut the time down on sanding by using the Dremel 80 grit sanding drum. I also found there was not enough room for my AT seal disk but I was able to kluge something by using the CTI phenolic seal disk and use JB Kwik to glue it to the top of the stack while using the last grain spacer glued to the disk. Popped in just like an AT seal disk with an O-ring.

I think it should be noted in the instructions that you need to sand the liner to fit in RMS hardware.
 

jd2cylman

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I’ve never had to sand a liner for cross loads. 🤷🏼‍♂️
And I’ve always managed to get the AT seal disc in by leaving out grain spacers as needed. All reloads have performed nominally.
 

JackC

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I’ve never had to sand a liner for cross loads. 🤷🏼‍♂️
And I’ve always managed to get the AT seal disc in by leaving out grain spacers as needed. All reloads have performed nominally.
Well, there are plenty of people on this thread who have had to sand the liner. It seems this problem started in 2020 or so.
 

JackC

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Well, I had the same issue with an M1101 I purchased on 07/22. I cut the time down on sanding by using the Dremel 80 grit sanding drum. I also found there was not enough room for my AT seal disk but I was able to kluge something by using the CTI phenolic seal disk and use JB Kwik to glue it to the top of the stack while using the last grain spacer glued to the disk. Popped in just like an AT seal disk with an O-ring.

I think it should be noted in the instructions that you need to sand the liner to fit in RMS hardware.
I flew the M1101 on 10/15 and everything worked well. The next day I tried to take the motor apart and could not get the nozzle assembly free from the rear closure because some unknown washer kept the nozzle from being pushed up through the front side of the rear closure. I had to use a Dremel saw then a hacksaw to break it into two to release the rear closure. I have never run into anything like this before. I would appreciate any insight.
 

Rocketjunkie

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I flew the M1101 on 10/15 and everything worked well. The next day I tried to take the motor apart and could not get the nozzle assembly free from the rear closure because some unknown washer kept the nozzle from being pushed up through the front side of the rear closure. I had to use a Dremel saw then a hacksaw to break it into two to release the rear closure. I have never run into anything like this before. I would appreciate any insight.
I have had the nozzle swell and not fit back through the rear closure. A Dremel with a sanding drum takes off the excess material and then you can push it out. More common with phenolic nozzles in long burn motors.
 

JackC

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I have had the nozzle swell and not fit back through the rear closure. A Dremel with a sanding drum takes off the excess material and then you can push it out. More common with phenolic nozzles in long burn motors.
Thanks for your response. Yep, I guess that is what happened to me, too. However, I didn't think a 4.7 second burn would qualify as a long burn motor but live and learn. Thanks, RJ!
 

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I have a question about how many casing spacers you can use for Pro98 motors. The product notes don't really make this clear. Can you use 2 regular spacers like with smaller case diameters? And if so, can you also use 2 regular + an XL spacer in a 98mm 6XL case to fly 4G reloads?
 

Cesaroni Technology

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I have a question about how many casing spacers you can use for Pro98 motors. The product notes don't really make this clear. Can you use 2 regular spacers like with smaller case diameters? And if so, can you also use 2 regular + an XL spacer in a 98mm 6XL case to fly 4G reloads?
CTI only recommends using 2 grain spacers in reloads.
 
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