L935

I assembled my first L935 last night.

1. What a monster! I cannot wait to fly it.

2. The aft grain slid out the liner. I put it back, but wanted to be absolutely positively sure, the concave end goes against the nozzle, correct? The flat end goes against the next grain?

3. I did not see any kind of extra threaded closure for the forward end. It was simply grains in liner, nozzle end, and forward end, like the Cesaroni reloads I am used to but with the white paper cap marked P. I am not missing some necessary additional threaded forward closure, right?

4. I applied grease to the O rings but I cannot imagine much remained on the forward end by the time it completed its journey down the length of the case.

Pro54-6XL?

There should be a liner, grains, nozzle, fwd ass'y w/delay & 2g ejection charge.

All you need is the case & aft closure (plus the delay tool).

The threaded end of the case is the aft end, not the forward end. And, yes, you need a closure to hole the fire in. The closure does not come with the reload and a 6XL load is a plugged motor with no ejection charge (no delay tool needed).

Plugged?

Did not see that in the specs. Cool

Yes I have the aft closure, used it on 2G and 3G motors, but I am still confused by this part -
https://www.wildmanrocketry.com/ProductDetail.aspx?product=3155

Anyone know for certain I got the aft grain packed in the correct direction? I am fairly sure but definitely would not mind confirmation!

Al,

All the 54/6XL's are plugged

Here is a pic. Hope this helps!

https://www.pro38.com/pdfs/Pro54_Case_Spacer.pdf

Grain orientation would be shown on CTI's website. I would look at the grain it is butting up against and make sure the 2 mating surfaces are opposite (flat up against curve) that's the correct orientation. Just not sure without looking at one to know off the top of my head.

Concave end towards flat end of grain next to it. This works the same as using grain spacers in larger 75 & 98 mm motors

All the Pro-54 cases have a rolled in forward end. There is only the case and the rear closure. All 6G-XL motors are plugged - smoke grain but no BP under the cap. The forward closure is part of the reload and looks like the ones with the shorter 54 mm reloads. I've flown 3 L935's and have another. Grease the case or it will be very difficult to get the spent reload out.

I've only flown one of the L935s, but IIRC the flat end of all the grains were aft and the concave ends were forward. That is the way it looked in the drawings timbucktoo linked in post #7

I agree about greasing the case. I don't know if it helps getting the burnt case out, but without the grease in the case, I couldn't get the forward o-rings to slide all the way in. That's a long case and the o-rings will dry out and get very hard to move if you don't grease the case to keep them lubed the whole way in.

BTW, I believe the threaded closure Wildman sells is made to replace the forward closure that comes with the reload and it allows you to put a threaded rod/bolt in the forward end for motor retention.

What are you flying the L935 in? What altitude/speed do you expect?

Handeman said:

BTW, I believe the threaded closure Wildman sells is made to replace the forward closure that comes with the reload and it allows you to put a threaded rod/bolt in the forward end for motor retention.

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That is correct. A more accurate name would be tapped forward closure. The rear closure does actually thread onto the motor case. The forward closure does not. Some of the plugged CTI 54 mm motors are tapped, but most are not. Here is a "thread", no pun intended on this topic from CJ.

https://www.rocketryforum.com/showthread.php?69010-CTI-54mm-Tapped-forward-closure-question

The L935 is an awesome motor. You will love it.

That diagram definitely shows concave forward, however my second to last grain with a flashlight and dowel look and feel like concave aft. Sigh. I wish someone from Cesaroni could weigh in or respond to my web site contact from yesterday. I am extremely nervous about getting it wrong in a motor of this magnitude. I suppose I could try to pop out that second to last grain myself to see, if it comes to that. Or, simply hold the flight for now.

This will be in a Punisher, sim says 14k but I think 11k is more realistic.

Thanks Handeman for that closure explanation!

Look at post #7. It is the CTI drawing.

watermelonman said:

This will be in a Punisher, sim says 14k but I think 11k is more realistic.

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CJ hit 12,668 ft on a CTI K815 skid in Australia. 14 k might be doable with an L935 depending on your build.

watermelonman said:

That diagram definitely shows concave forward, however my second to last grain with a flashlight and dowel look and feel like concave aft. Sigh. I wish someone from Cesaroni could weigh in or respond to my web site contact from yesterday. I am extremely nervous about getting it wrong in a motor of this magnitude. I suppose I could try to pop out that second to last grain myself to see, if it comes to that. Or, simply hold the flight for now.

This will be in a Punisher, sim says 14k but I think 11k is more realistic.

Thanks Handeman for that closure explanation!

Click to expand...

Gregg Halligan got 18k on L1000w at ROCstock last weekend in his PunisheR. He did 15,900 ft on a K1440 also

I got 15,178 ft. Thrust Curve said just over 10k on a K1440

A real drag race in the west

Kenny

KenRico said:

Gregg Halligan got 18k on L1000w at ROCstock last weekend in his PunisheR. He did 15,900 ft on a K1440 also

I got 15,178 ft. Thrust Curve said just over 10k on a K1440

A real drag race in the west

Kenny

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Nice. The Punisher will be my next new project. Have an L935 and a K1440 in my garage with a bunch of other cool motors waiting to go up. I don't get out much!

Wayco said:

Love this motor! Flown it several times in my 3" Darkstar to 12,800 ft. Last month I put one in my old Blackhawk 54 "Silver Streak" and flew it to 23,230 ft.
I have a Punisher that I want to build as a sustainer in a two stage rocket with a 3" MD booster, but that's a project for next year.

Click to expand...

I joke that you and Hardline buy them in 6-packs

Kenny

So I got home from work today and popped out the second grain from bottom. Concave side faced nozzle. So, I figure the feedback here was either wrong or did not apply to this specific motor, and start to pack it all back together.

Then out of the corner of my eye I notice the next grain up looks different. I feel around, then slide it out too, and sure enough, it is duplicate but concave side forward. What the heck?

I do not want to fly or purchase any more until I hear back directly from Cesaroni. This is simply too much power to take chances with. Maybe the grain orientation does not matter, but in that case they could at least tell me.

Concave side up! If you really want to communicate with CTI, go here https://www.pro38.com/contact.php
We can't really expect the manufactures to read thru all of the various forums, right?
12k on my wildman DD. I must be doing something wrong.....

KenRico said:

I joke that you and Hardline buy them in 6-packs

Kenny

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Not exactly a six pack, but our bin of big 54's is HEAVY:

I dug down to the bottom and pulled out a couple of L935's, opened them up and both had the concave end of the grain pointing up toward the top of the motor.


Even the top grain with the BP pellet has the concave end at the top:


OK, now I'm back to my morning routine, drinking coffee and solving the mysteries of the rocket world....

cbrarick said:

Concave side up! If you really want to communicate with CTI, go here https://www.pro38.com/contact.php
We can't really expect the manufactures to read thru all of the various forums, right?
12k on my wildman DD. I must be doing something wrong.....

Click to expand...

Oh certainly not; I wrote them via that form a day before posting here.

I started exploring this deeper today, and found that all six grains came out fairly easily. Top being #1, 1-4 were all concave up. #6, I shall never know, as it was the one that fell out and started this confusion. However I am certain that #5 was concave side down when I received the motor. I put it back together, concave up, for all six grains.

Notably, both the bottom grains fell out of the liner with even a strong tilt. I would not be at all surprised if the bottom two fell out and were hastily shoved back in at some point during handling. Also there was no instruction sheet in this tube, not sure if they are included in motors of this size but every 38mm and 54mm I have used before came with one. The motor itself was still sealed in the pink plastic bag, though.

No answers from Cesaroni yet, hoping they come before launch.

This is from CTI web site.

Wayco said:

OK, now I'm back to my morning routine, drinking coffee and solving the mysteries of the rocket world....[/FONT]

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Thanks a ton for checking yours!

timbucktoo said:

This is from CTI web site.

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Yes, I saw that when you posted it previously. I appreciate your trying to help but I was looking for specifics to this motor. Those are instructions for case spacers and do not even mention grains though they are shown. I know that grains can differ quite a bit from motor to motor, and man who signed off my L2 test instilled quite an emphasis on safety in me, especially as motors increase in size.

I am still somewhat alarmed at the lack of instructions included, the lack of response from manufacturer, and apparent mistake in assembling this particular motor at their site. Or maybe I am making way too big a deal of it, and a backwards grain is no big deal, but I err on the safe side.

Have you tried sending a PM to Jeroen_at_CTI ?
He is usually very responsive.!

I have one of these sitting in my basement. Will fly it when we get back to our winter field on a calm day.

Is greasing the O-rings mandatory? I have never done that with a CTI reload.

Wayco said:

Not exactly a six pack, but our bin of big 54's is HEAVY:

I dug down to the bottom and pulled out a couple of L935's, opened them up and both had the concave end of the grain pointing up toward the top of the motor.

Even the top grain with the BP pellet has the concave end at the top:

OK, now I'm back to my morning routine, drinking coffee and solving the mysteries of the rocket world....

Click to expand...

Nice. I want to hang with you guys Wayco!

Bat-mite said:

I have one of these sitting in my basement. Will fly it when we get back to our winter field on a calm day.

Is greasing the O-rings mandatory? I have never done that with a CTI reload.

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Really the only reason for greasing the O-rings on all motors is to keep them from tearing and breaking when inserting them into the casing.