CTI Discussion Thread

[Tim51]

Excited to fly a H125 that I'm picking up from Wildman on Saturday at Michiana Mayhem. This will be my L1 certification flight.

Good choice - I did my L1 on the same motor. I didn't fly any more Classic propellant for a while after, as I wanted to try the more exotic flavours, but recently I've come back round to it and appreciate its qualities.

 

[0011001100]

Excited to fly a H125 that I'm picking up from Wildman on Saturday at Michiana Mayhem. This will be my L1 certification flight.

Be careful with it. I've seen 5 of them cato before we began gluing the forward closures in.

 

[Nytrunner]

Be careful with it. I've seen 5 of them cato before we began gluing the forward closures in.

Gluing in a 2grain 38?

 

[Banzai88]

Gluing in a 2grain 38?

Gluing the forward delay in 38mm CTI motors is becoming a thing. Would have saved two flights of mine last year where I got o-ring blow by. Carbon track was clear as a bell along the liner and the top of the case. One was so bad it ate a full 1/4 inch of the o-ring.

I just recently learned about gluing the 38s to prevent that since I bought into CTI54mm hardware, where, apparently, darn near everyone glues them as well because of the same type of failure.

 

[SeanW78]

Gawd I hope it goes well. Now I'll have to look up the best and safest way to glue a grain in. May need to add epoxy to my field kit.

 

[Banzai88]

Gawd I hope it goes well. Now I'll have to look up the best and safest way to glue a grain in. May need to add epoxy to my field kit.

It's NOT gluing a grain in, it's gluing in the delay element/forward closure. Grain gluing is something else altogether.

Everyone seems to have their own method, but I've been using 5 minute epoxy in double bubble packs at the field after any delay drilling that I deem necessary. Just enough glue to seal things up and not have it drip all over.

 

[0011001100]

Gluing in a 2grain 38?

Yes as advised by Robert from AMW after 3 of 5 motors catoed in one morning. All from the same lot.

 

[Tim51]

Gluing the forward delay in 38mm CTI motors is becoming a thing. Would have saved two flights of mine last year where I got o-ring blow by. Carbon track was clear as a bell along the liner and the top of the case. One was so bad it ate a full 1/4 inch of the o-ring.

I just recently learned about gluing the 38s to prevent that since I bought into CTI54mm hardware, where, apparently, darn near everyone glues them as well because of the same type of failure.

Interesting - I've never glued 38s. Being in the UK I've flown CTI motors exclusively for 5 years* with only 1 38mm cato. Following a 54mm 4G cato 2 years ago I epoxy those (and tend to do that for 54mm 3G unless I buy the motor immediately prior to the launch) but that's it.
*For that period CTI were the only HPR motors available, although that has very recently changed.

 

[SeanW78]

It's NOT gluing a grain in, it's gluing in the delay element/forward closure. Grain gluing is something else altogether.

Everyone seems to have their own method, but I've been using 5 minute epoxy in double bubble packs at the field after any delay drilling that I deem necessary. Just enough glue to seal things up and not have it drip all over.

5 minute sounds like the plan. I don't want any mishaps and this seems like a fairly simple failsafe on not popping the forward closure.

 

[Banzai88]

5 minute sounds like the plan. I don't want any mishaps and this seems like a fairly simple failsafe on not popping the forward closure.

Use just enough to not have it goop out and glue the motor liner into the case!

 

[SeanW78]

Use just enough to not have it goop out and glue the motor liner into the case!

For sure! I'm going to lube the motor with vaseline before inserting it into the casing too.

 

[jd2cylman]

For sure! I'm going to lube the motor with vaseline before inserting it into the casing too.

Nope. Jeroen (former CTI expert/employee) told me to use a good quality silicone spray inside the motor case then put the reload in.

 

[TBob]

Nope. Jeroen (former CTI expert/employee) told me to use a good quality silicone spray inside the motor case then put the reload in.

+1

 

[Tim51]

Nope. Jeroen (former CTI expert/employee) told me to use a good quality silicone spray inside the motor case then put the reload in.

I actually use lithium grease which works well.

 

[tim cubbedge]

Nope. Jeroen (former CTI expert/employee) told me to use a good quality silicone spray inside the motor case then put the reload in.

It is even stated in the instructions.

 

[Saint_Tiki]

Hi. New guy. Flew my first HPR today on a CTI H152 2-grain reload. Looks like these have 1.3g of BP inside the ejection charge. I'm running a 3" diameter rocket with about a 9-10" section of tubing where the parachute sits between the top of the MMT and nosecone shoulder. The calc says about 0.33g of BP is required for 10 PSI. I've flown the rocket on some AT Hobbyline reloads that had 0.7g of BP and that worked great, confident deployment, not too much bang. I should also note that there is almost zero free volume inside the body tube when the rocket is packed for flight. The chute is pretty big because it's sized for when I add the AVBay and fly this rocket on dual deploy. And the body tube used to be longer but due to an anomaly... it's a few inches shorter now. So that's all the space I have and it's completely full of laundry. Not sure if that affects the calc at all.

Today, I felt like the CTI ejection charge was way too much. The force of the ejection actually ejected my parachute out of my ChuteRelease resulting in a 2400' main deployment... Drifted 0.5 miles and barely missed the power lines, successful cert! Haha. But it also resulting in what I would call excess charring on the kevlar shock cord protector and some charring on my 15 foot nylon shock cord, even with a handful of dog barf used.

Is it possible to pop the cover and reduce the amount of BP? Any ideas for this?

Calc says at 1.3g, I'm getting 35 PSI and 250lbs of force on the nosecone. Seems like my rocket might pop from that pressure.

 

[Cesaroni Technology]

Yes we do put 1.3 grams of black powder for the P38 ejection charge. If needed you can carefully remove the plastic cap and readjust the amount of powder required, then replace and secure the cap.

 

[Saint_Tiki]

I wanted to confirm something. I've got a Pro38 2G motor, H225, manufactured 14 Aug 2018. Looks like this specific motor doesn't have the same nozzle size as the other 2G 38mm's and therefore shouldn't require the ignition pellet modification?

 

[crossfire]

Hi CTI
Been flying your motors for many years. I filed my 1st warranty claim with a dealer. Just wondering how long it takes to get replacement case and reload?
Thanks for your help

 

[Cesaroni Technology]

I wanted to confirm something. I've got a Pro38 2G motor, H225, manufactured 14 Aug 2018. Looks like this specific motor doesn't have the same nozzle size as the other 2G 38mm's and therefore shouldn't require the ignition pellet modification?

Correct. The Pro38 2G WT doesn't require the pellet modification.

 

[Cesaroni Technology]

Hi CTI
Been flying your motors for many years. I filed my 1st warranty claim with a dealer. Just wondering how long it takes to get replacement case and reload?
Thanks for your help

That will depend on a few factors, the main one being when your dealer places their next order. Then your case and reload would be shipped.

 

[crossfire]

That will depend on a few factors, the main one being when your dealer places their next order. Then your case and reload would be shipped.

Ok it's from WM. It's a 1 grain 38mm and 1 grain case.

 

[tbonerocketeer]

Are you sure about that. All the dealers I know removed them from their websites and liquidated their stock. Only place I have found them is AMW in very limited supply. Loads for the 75 mm line would be great

I'm absolutely certain about that. We never stopped selling them. We do rarely sell any, I guess I know why now.
We might even have some Scalded Tiger (VMax) in stock in 54mm. The only 75mm loads are skidmark.

https://pro38.com/products/pro54/motor.phphttps://pro38.com/products/pro75/motor.php
See the bottom of the links.
[/QUOTE]
If I remember when I get home, I will copy the email that said these are no longer available. The hub wasn't either.

 

[crossfire]

Flying an I800 VMAX tomorrow in a 65 ounce rocket. Will report the results.

How did it go

 

[tfish]

Yes I've already seen them, we're trying to figure out what happened.

Any up dates on these...

or the issue with the FC on 54mm motors?

Tony

 

[tfish]

Yes we are certainly aware of the issue, I've been testing them for the last few weeks. Although I've yet to have a burnthrough or even a bulge , it's been plain to see that the gasses aren't flowing evenly around the forward closure as we would like. I think the solution might be simple but need to do more testing.

Any updates on the 54mm issue?

Any CTI recommend field fixes?

Tony

 

[Cesaroni Technology]

Any up dates on these...

or the issue with the FC on 54mm motors?

Tony

We're still trying to figure out why the nozzles deteriorated so badly. It's typical for the nozzle to get some deep grooves in the expansion due to the length of burn. But we've fired a few M840's and have not received the same results. Makes it hard to understand why a couple of nozzles deteriorated so bad.
We're working on a new forward closure, but testing them takes some time, between doing other things and also having to wait on the weather to cooperate. So far things are looking promissing.

 

[tfish]

We're still trying to figure out why the nozzles deteriorated so badly. It's typical for the nozzle to get some deep grooves in the expansion due to the length of burn. But we've fired a few M840's and have not received the same results. Makes it hard to understand why a couple of nozzles deteriorated so bad.
We're working on a new forward closure, but testing them takes some time, between doing other things and also having to wait on the weather to cooperate. So far things are looking promissing.

So just keep flying both items as they are?

Tony

 

[Rocketjunkie]

We're still trying to figure out why the nozzles deteriorated so badly. It's typical for the nozzle to get some deep grooves in the expansion due to the length of burn. But we've fired a few M840's and have not received the same results. Makes it hard to understand why a couple of nozzles deteriorated so bad.

Were the motors in a larger diameter rocket? I've had the White fireball in the back of the rocket pretty thoroughly cook everything in the back of the rocket. One example was a K250 in my Magnum. 5.5" diameter with 6 outboard 29 mm mounts. Rocket came back with all 6 empty outboard tubes burned away and everything in back well scorched, including the SU motor's nozzle.

 

[Steve Shannon]

We're still trying to figure out why the nozzles deteriorated so badly. It's typical for the nozzle to get some deep grooves in the expansion due to the length of burn. But we've fired a few M840's and have not received the same results. Makes it hard to understand why a couple of nozzles deteriorated so bad.
We're working on a new forward closure, but testing them takes some time, between doing other things and also having to wait on the weather to cooperate. So far things are looking promissing.

The forward closure issue affects the longest 38mm motors also.