Problem with CTI G33 Motor

[Richard Dierking]

I'm surprised motor instructions aren't filled with fine print about fliers assuming all but very limited liability.
Oh, wait... https://www.pro38.com/pdfs/Pro29_instructions.pdf

Quote from a few posts ago. Thank you Charles! These directions are interesting.
For example, it says Use Within 1 Year of Manufacturing Date. Well, I received the last 5 of these motors Dated APR 15 2019 on August 3, 2020. And, just wait when all the motors that vendors have stocked during CV start being used. There's going to be some ones that don't pass the pull date "smell" test. The two I got dated NOV 22 2018 were received in July.
Also, the directions say Temperature Range: -5C to 30C. This is 86 F. I laugh at 86 F; it's not even warm here until >100 F. Well, no launching these motors in the Southwest US from about June to October. LOL

And, Steve, the directions state:
Only use the igniter provided with the reload kit. Do not interchange with other Pro29 igniters or with any other type of igniter.
So, sorry, if that first igniter doesn't work, just throw the motor away. ;-)

 

[jqavins]

I’m extremely grateful to John Coker for redesigning the Motorcato.org website.

I had no idea that we have John to thank for motorcato.org on top of thrustcurve.org and great videos. That man is powerhouse!

But our most daunting problem still is getting people to use it. Just the other day a friend of mine repeated the remark that the MESS report system is a black hole. Somehow we have to get the word out that we have changed that completely and that it’s now a tool for all of us.

And if we could get the manufacturers to use it, maybe action could be taken even faster. Meaning no criticism of NAR, TRA, and CAR reporting, but so much the better if that step weren't necessary.

And I still don't buy the 'we don't have the denominator' argument. You don't have to know how deep the ocean is to tell that next wave is going to swamp you. Barring a sudden fad for flying a certain kind of motor, or a new motor, a change in reporting rates is still a signal. If you put it on a control chart, you wouldn't need to know the scale of the Y axis to determine a background variability and spot a change from that.

True, and on top of that the manufacturers do know how many are sold, more or less. They don't know the distributors' and retailers' stock levels (I assume) of the flyers' stock levels, but their sales figures should get you pretty close.

 

[Richard Dierking]

The date code on the motor packaging should go on the flight card. This would encourage people to collect the data before discarding the packaging. And, if the motor did fail, you could go back to the flight card for this important information.

There should be an ongoing campaign to encourage people to use the motorcato.com website. I'm thinking others could input data to the website, correct? So, if it's not the person that bought the motor, it could be someone else entering reports out for a launch.
Hum, sounds like an excellent topic for a Tripoli report.

 

[Steve Shannon]

The date code on the motor packaging should go on the flight card. This would encourage people to collect the data before discarding the packaging. And, if the motor did fail, you could go back to the flight card for this important information.

There should be an ongoing campaign to encourage people to use the motorcato.com website. I'm thinking others could input data to the website, correct? So, if it's not the person that bought the motor, it could be someone else entering reports out for a launch.
Hum, sounds like an excellent topic for a Tripoli report.

Yes, the report can be made by others. It just shouldn’t be reported more than once.
I started reporting the few catos that occurred at our field several years ago, just to make sure they were were done. Once you have done a few it’s easy. I haven’t had any to report since John Coker rebuilt the database, but I’m sure it’s even easier now.
I was actually considering doing a Tripoli Report article on this.

 

[UhClem]

For example, it says Use Within 1 Year of Manufacturing Date.

That is a problem. NFPA 1125 has shelf life requirements (7.9). While it says that motors should have a use by date if shelf life is less than 10 years it also requires motors to be withdrawn if they fail to meet requirements before 5 years have passed. The use by date doesn't exempt CTI from that requirement.

 

[Richard Dierking]

I was actually considering doing a Tripoli Report article on this.

If you choose to do that, please let us know. You write excellent articles Steve!

Of course there are the losses people experience when a motor CATO's. My experience is a bit unusual because people don't usually static test commercial motors. But, motor failures in rockets, CATO's, or failures later in the launch are more dangerous, can damage launch equipment, and create additional fire hazards.

People should have the CATO website going when they are shopping for motors.
We should help the manufacturers recognize problems and encourage them to take action quickly.

 

[Joshua F Thomas]

I bet it would. Like a switch to single use only, or an exit from the market.

It seems like the number of options for single use in G and up are limited? Can someone comment on that? I'm new to HPR and it looks like only Aerotech has G+ single use motors?

 

[Steve Shannon]

It seems like the number of options for single use in G and up are limited? Can someone comment on that? I'm new to HPR and it looks like only Aerotech has G+ single use motors?

I don’t know of any other manufacturers still in business who make single use G or larger motors.

 

[Steve Shannon]

I bet if they started to take responsibility for all the damages that would change. Like replacing a motor and case vs having to replace an entire rocket and all the work that went into it.

The change most quickly noticed would be an increase in motor prices. Companies never pay for warranties; customers do.

 

[Joshua F Thomas]

If I knew that my rocket and other damages were covered if the motor had destruction, my confidence would go up, and I'd be more likely to buy one of those motors. Increased sales.

 

[Steve Shannon]

Steve, I almost tagged you when I made the Vmax remark. Glad to see I didn't need to

I've heard the comment that CTI says they haven't had any reports, sometimes in the same weekend that Wildman Tim hands me the warranty replacement and comments that it's the fourth one that shipment. it makes me wonder if there is a gap on the CTI side. That warranty replacement info, or the request forms, aren't getting to the right place.

And I still don't buy the 'we don't have the denominator' argument. You don't have to know how deep the ocean is to tell that next wave is going to swamp you. Barring a sudden fad for flying a certain kind of motor, or a new motor, a change in reporting rates is still a signal. If you put it on a control chart, you wouldn't need to know the scale of the Y axis to determine a background variability and spot a change from that.

That has been my response about the denominator argument as well. But both arguments are correct. Alan was never saying that without the denominator we have nothing and I was never arguing that the denominator wouldn’t be useful information. Some designs result in a higher than acceptable failure rate. It only takes a handful of motors to work well at sea level to be certified. But if 1/20 catos that’s too many. Having an idea of the production helps in this regard.
But then something like the one grain Pro38 problem comes along and all of a sudden we see the “wave“ as you so aptly call it. We see a huge rise in the numerator and even though we don’t know the denominator we can see there’s a problem.
I’ve spoken to vendors and gotten the same report, that they have been reporting things to their CTI reps. I believe the vendors.

 

[Steve Shannon]

Is removing the pellet a "manufacturer approved" mod? I thought only cutting down the pellet was approved by CTI...

Cris,
I don’t know, but I assume you’re right. Removing the pellet doesn’t make a motor more likely to fail after ignition; it simply makes it harder to light. I fly at research launches, only make changes I'm confident about, and accept full responsibility for any failures.

snip…

And, Steve, the directions state:
Only use the igniter provided with the reload kit. Do not interchange with other Pro29 igniters or with any other type of igniter.
So, sorry, if that first igniter doesn't work, just throw the motor away. ;-)

I intend to burn every motor I have. Thank goodness for Tripoli Research Launches.

 

[AeroTech]

It was an expensive proposition to re-enter the single-use high-power market so we did it incrementally, over a period of 8 years. There were also several technical hurdles to overcome. In addition, the overall market is not very large.

Yet, there are now 33 motors in the DMS line:

2020 DMS Brochure

And two more will be released soon.

It seems like the number of options for single use in G and up are limited? Can someone comment on that? I'm new to HPR and it looks like only Aerotech has G+ single use motors?

 

[Bamraam]

Burned some G33's today to verify any problems, 8 in total. Oddly, the first three lit the pellet but failed to light the motor. The two after we fired without the nozzle cap in place, they did light but a few seconds after the pellet. I don't think the cap is an issue but just seemed odd. Biggest thing I niticed with the first 5 motors was the loud pop from the pellet, seemingly pressurizing the motor far more than needed, then the drop in presure snuffing out the motor before it can light (similar to the VMax issue snuffing out the delay). With this high pressure I think any obstruction could easily breach the motor. We reduced the size of the pellet and the next 6 motors performed nominally (even with nozzle cap in place). I'm sure this will eleviate most of the issues with this motor, but I suspect that some were failing due to the size of the igniter, occasionally blocking the nozzle throat and causing a CATO. The smaller pellet should help by not creating as much initial pressure. We're also looking into a smaller igniter for the smaller throated nozzles, but they're not yet approved in Canada.

 

[Dipstick]

Burned some G33's today to verify any problems, 8 in total. Oddly, the first three lit the pellet but failed to light the motor. The two after we fired without the nozzle cap in place, they did light but a few seconds after the pellet. I don't think the cap is an issue but just seemed odd. Biggest thing I niticed with the first 5 motors was the loud pop from the pellet, seemingly pressurizing the motor far more than needed, then the drop in presure snuffing out the motor before it can light (similar to the VMax issue snuffing out the delay). With this high pressure I think any obstruction could easily breach the motor. We reduced the size of the pellet and the next 6 motors performed nominally (even with nozzle cap in place). I'm sure this will eleviate most of the issues with this motor, but I suspect that some were failing due to the size of the igniter, occasionally blocking the nozzle throat and causing a CATO. The smaller pellet should help by not creating as much initial pressure. We're also looking into a smaller igniter for the smaller throated nozzles, but they're not yet approved in Canada.

Great to see a response here from CTI directly I presume? It would be really nice to have a continued CTI presence on the forum again!

 

[jqavins]

...

Burned some G33's today to verify any problem...

Anyone thinking the manufacturers don't take notice, take notice.

 

[Evolvant]

Burned some G33's today to verify any problems, 8 in total. Oddly, the first three lit the pellet but failed to light the motor. The two after we fired without the nozzle cap in place, they did light but a few seconds after the pellet. I don't think the cap is an issue but just seemed odd. Biggest thing I niticed with the first 5 motors was the loud pop from the pellet, seemingly pressurizing the motor far more than needed, then the drop in presure snuffing out the motor before it can light (similar to the VMax issue snuffing out the delay). With this high pressure I think any obstruction could easily breach the motor. We reduced the size of the pellet and the next 6 motors performed nominally (even with nozzle cap in place). I'm sure this will eleviate most of the issues with this motor, but I suspect that some were failing due to the size of the igniter, occasionally blocking the nozzle throat and causing a CATO. The smaller pellet should help by not creating as much initial pressure. We're also looking into a smaller igniter for the smaller throated nozzles, but they're not yet approved in Canada.

I experienced the loud "pop" as well. Both mine when that happened over pressurized and blew the nozzle out of the case. Ruining the case by the way. The case would mushroom out where the aft closure screws in. It would spit the closure out and nozzle out. Interesting enough, neither actually lit. Both on the pad spit the nozzles out and went nowhere. The grains weren't lit either.

On one of mine I totally think I caused the "igniter problem" you are describing. The "mini" igniter that was sent with the motor was still too fat to fit through the small hole in the nozzle. So, I pulled off the nozzle and threaded the igniter from the top to bottom. Then I re-assembled the motor with igniter threaded through the nozzle. Over pressurized and did what was described above. I thought it was my fault because I was working around an igniter issue on the first one. Second one, igniter was small enough to fit though but same problem.

I think the nozzle is so small it's almost impossible to not over pressurize the case on light..

 

[Joshua F Thomas]

It was an expensive proposition to re-enter the single-use high-power market so we did it incrementally, over a period of 8 years. There were also several technical hurdles to overcome. In addition, the overall market is not very large.

Yet, there are now 33 motors in the DMS line:

2020 DMS Brochure

And two more will be released soon.

I'm not unhappy with Aerotech, I was just wondering what the options were like.

 

[Richard Dierking]

The interest of the manufacturers is encouraging.
They didn't mention what date codes they were firing. Got to be a little fun static firing all those motors. Anyway, if they don't keep retains, I still have the NOV 22 2018 motor in the unopened package if they would like to try it.

I think the motorcato website would be an excellent subject for the sticky post. More people need to know about this website and start noting things like the date codes when they are using motors. Don't throw the packaging away until it's a done deal!

 

[Bamraam]

Great to see a response here from CTI directly I presume? It would be really nice to have a continued CTI presence on the forum again!

I've been with CTI since 2007, and recently been promoted to management. Figure I should start keeping an eye on things...

 

[Bamraam]

I experienced the loud "pop" as well. Both mine when that happened over pressurized and blew the nozzle out of the case. Ruining the case by the way. The case would mushroom out where the aft closure screws in. It would spit the closure out and nozzle out. Interesting enough, neither actually lit. Both on the pad spit the nozzles out and went nowhere. The grains weren't lit either.

On one of mine I totally think I caused the "igniter problem" you are describing. The "mini" igniter that was sent with the motor was still too fat to fit through the small hole in the nozzle. So, I pulled off the nozzle and threaded the igniter from the top to bottom. Then I re-assembled the motor with igniter threaded through the nozzle. Over pressurized and did what was described above. I thought it was my fault because I was working around an igniter issue on the first one. Second one, igniter was small enough to fit though but same problem.

I think the nozzle is so small it's almost impossible to not over pressurize the case on light..

Yes the nozzle throat on smaller motors produces challenges to find the right igniter. If the igniter didn't fit in the nozzle then that's our fault. We check each igniter to ensure that they fit in the smallest nozzles, but manufacturing tolerances can still cause the odd igniter to not fit. Hopefully the new igniter we're looking into will soon be approved. Did you apply for warranty on your two cases?

 

[Bamraam]

The interest of the manufacturers is encouraging.
They didn't mention what date codes they were firing. Got to be a little fun static firing all those motors. Anyway, if they don't keep retains, I still have the NOV 22 2018 motor in the unopened package if they would like to try it.

I think the motorcato website would be an excellent subject for the sticky post. More people need to know about this website and start noting things like the date codes when they are using motors. Don't throw the packaging away until it's a done deal!

We didn't have any P29's with the '18 date code, but we had also made P38 and 54's on that date without any issues, the propellant isn't the problem. If anyone has these motors left you can modify the pellet in this motor as was done with the P38 1G issue.

 

[tfish]

I've been with CTI since 2007, and recently been promoted to management. Figure I should start keeping an eye on things...

How will CTI be getting "the word out" about the above "fix" to the G33 motor to flyers?


Also, are you aware of issues with some of the 54mm motors burning through at the forward closures?

Tony Alcocer

 

[Richard Dierking]

Yes the nozzle throat on smaller motors produces challenges to find the right igniter. If the igniter didn't fit in the nozzle then that's our fault. We check each igniter to ensure that they fit in the smallest nozzles, but manufacturing tolerances can still cause the odd igniter to not fit. Hopefully the new igniter we're looking into will soon be approved. Did you apply for warranty on your two cases?

I did through Wildman Rocketry. But, I already purchased a replacement case and closure because I want to use the 6 motors I have (includes one NOV 22 2018).

If smaller igniters are going to be supplied, will replacement igniters also be readily available for people that need to recycle the igniter? This would be very important.

There's a launch next weekend at FAR. This is a research launch. I'll follow the directions for the reduction of the pellet on the NOV 22 2018 motor and static test it. Then, I will open up the nozzle just a bit on one of the APR 15 2019 motors and fire that one. I'll have the GoPro going at 240 fps for the test (Not right above the motor thank you).

I have a lot of projects going on currently, but I'll try to post some measurements and photos today before I modify anything.

All modifications should be officially reviewed and blessed by TRA/NAR in my opinion.

And, if Santa is listening, my wish is for long burn 38 mm. And, I've been a good boy this year. Well, pretty good.

 

[Bamraam]

Yes we're also aware of the P54 issue, it likely won't be as easy a fix, but I started some initial testing on them last week also. First tests were inconclusive.
I'll get "the word out" next week about the G33's to the organizations.

 

[Bamraam]

I did through Wildman Rocketry. But, I already purchased a replacement case and closure because I want to use the 6 motors I have (includes one NOV 22 2018).

If smaller igniters are going to be supplied, will replacement igniters also be readily available for people that need to recycle the igniter? This would be very important.

There's a launch next weekend at FAR. This is a research launch. I'll follow the directions for the reduction of the pellet on the NOV 22 2018 motor and static test it. Then, I will open up the nozzle just a bit on one of the APR 15 2019 motors and fire that one. I'll have the GoPro going at 240 fps for the test (Not right above the motor thank you).

I have a lot of projects going on currently, but I'll try to post some measurements and photos today before I modify anything.

All modifications should be officially reviewed and blessed by TRA/NAR in my opinion.

And, if Santa is listening, my wish is for long burn 38 mm. And, I've been a good boy this year. Well, pretty good.

If the pellet modification is made there won't be a need to replace the igniter. Besides if the first igniter (ematch) doesn't light the motor, likely the pellet is gone and another ematch won't work without the pellet anyway.
Since you're attending a research launch I guess you could do what you want with the motor (though some modifications may void your warranty), but I really don't think you need to open up the nozzle. Just be sure the igniter fits through the nozzle.

 

[Richard Dierking]

If the pellet modification is made there won't be a need to replace the igniter. Besides if the first igniter (ematch) doesn't light the motor, likely the pellet is gone and another ematch won't work without the pellet anyway.
Since you're attending a research launch I guess you could do what you want with the motor (though some modifications may void your warranty), but I really don't think you need to open up the nozzle. Just be sure the igniter fits through the nozzle.

OK. For recycling, I was just thinking about the prior posts where people had motors that didn't go on the first try. Any official procedure should address this potential situation. If it doesn't, people will start resorting to all kinds of solutions, and keep in mind that most of these motors are used at commercial launches.

I think it's important to let people know that if the suppled igniter doesn't fit through the nozzle when inserting it at the pad (standard procedure), it's not a good idea to remove the nozzle and pull the leads of the igniter through the nozzle throat.
Again, how would this affect the warranty since they are using the supplied igniter and haven't modified anything.

I need to inspect and do some measurements this afternoon and I will consider what you said.

To be clear, is it correct that modifying the pellet doesn't void the warranty?

 

[tfish]

CTI's 38mm 1 grain pellet info..

https://www.pro38.com/pdfs/Pro38_Pellet_Modfications_v1.2.pdf
https://www.pro38.com/pdfs/Bulletin_Pro38_1G_Pellet_Issue_v1.2.pdf
Tony

 

[Charles_McG]

@Bamraam , I’m planning a flight as early as tomorrow with an H53MY. The 5 grain motor has more length/volume to disperse that initial pop. Have you had any reports that would suggest this motor needs a trimmed starter, too?

 

[Richard Dierking]

I apologize for any interruption in the questions being asked. I'm going to be as quick as possible with this. I wanted to post about the NOV 22 2018 motor first. Then, I'm planning on going pretty quickly through the 5 APR 15 2019 motors I have.
I have the procedure for trimming the pellet. It's 7 pages long. Just saying, so the vendor is going to sell someone a motor and direct them to this document. Verses, telling them that they could buy a AT G with no modifications necessary. And, if the buyer doesn't feel comfortable doing it themselves, the vendor is going to stop what they are doing and tend to this. Good luck with that.

Again, these are 29 mm, 3 grain, G33
Date Code: NOV 22 2018
Igniter: 2.39 x 2.56 mm at the solder connection to the head.
Nozzle: 2.78 mm at aft end of nozzle. It's smaller diameter at the forward end. (Photos)
Does the igniter pass thru the nozzle: Yes
It's very difficult to remove the grains from the liner. I used a 7/8" diameter wood dowel. This would be difficult to do in the field if you didn't have something like this dowel without damaging the grains.
Started to score the pellet after removal with 1/4" aluminum rod and it broke almost immediately. However, I was able to trim in down and re-insert it. Again, this would be difficult to do in the field. I'm in my shop with all my tools and materials, with no wind.
I drilled out the nozzle throat with a 7/64 drill bit so it was uniform. This motor will be static tested on October 3. May the Force be with me.