Discussion in 'Propulsion' started by ATGM, May 16, 2015.
Was that you at Bama Blastoff?
We spoke after, you showed me the case. Either you or Chris S. said that the case would be replaced. Very glad to hear it was, but I was not sure with whose (AT/CTI) case.
Curious, how long did it take for your to receive the replacement case and reload? Days, weeks, months?
ANYTHING that beats CTI's YEAR PLUS replacement cycle is $$$$$$$$$
Got the motor a month later from Chris at a launch in Georgia. Think it took about 2-3 months for the case which came direct from Aerotech.
That does not sound too bad given the hardware availability problem reported on this thread.
I had my first CATO today on an Aerotech 29/40-120 G76-7G. The motor discharged thrust out the nozzle at launch, and within a second, out the forward closure through the ejection charge well. The inside of the rocket was toasted pretty well and took a nose first landing. That crushed anything that hadn't been scorched. I gave the motor enough time to cool off and took it apart to see where I went wrong. All of the o rings and the forward insulator were intact with the exception of the delay o ring. That, as well as the delay liner and spacer were completely gone. The charge well hole was also burned open to about 1/4" diameter. The inside of the casing is still in good shape and all of the threads stayed clean and undamaged. It looks as though the delay burned through in a second or less instead of the 7 seconds it was set for. I've looked at the Aerotech warrantee, and this appears to fall under one of their exceptions for coverage. I'm okay with owning my own mistakes, but I'm not sure where this one went wrong. I'm open to suggestions from people with more experience than me on where I might have made my mistake. Thanks for helping out a new guy.
This failure is almost always the delay spacer not being installed towards the propellant grain, but instead being put forward into the closure.
This is how I CATO'd a G-64W. A lesson I won't soon forget.
Another possibility is an overdrilled delay, though at 7s that's somewhat less likely.
Good to know. My daughter had the same thing happen a couple years ago on some F motor in that’s hobby case. I was always going to see about getting a new fwd closure for it but never have.
I appreciate the replies. I took another look at the inside of the forward closure and there is a residue on the inside face that would have needed an air gap to be deposited. I think that is a clear indicator I had the spacer on the wrong side. Tough lesson, but at least I shouldn't have to repeat it. Thanks all.
I had the same thing happen to both my cases on the same 2 motor cluster flight. They were G53FJ. Everything was assembled correctly including the delay grain spacer and the delays were not drilled. These were a brand new batch and what I noticed about them was the delay liner was very loose in the forward closure. If I tipped it upright the delay and liner fell right out. I didn't think it would matter. It seems that it did.
I started wrapping each delay liner with a layer of masking tape after that and didn't have another failure.
BTW, I sent photos of the parts to Aerotech and received two new forward closures and two reloads.
+1 Beat me to it! The delay liners lately supplied with the reloads have been very loose. In the last 2 G-64's I used this year I had to tape the delay liners to get a snug fit in the delay well. I use cellophane tape. The flights were nominal. I had to tape other loads previously also. There has been discussion about this in other threads or earlier in this thread. Make sure the delay liners fit snugly in the well.
Had the pleasure of working with a 98-15360 case and N-2200 Dark Matter reload. Easy to assemble and everything fit like a glove. Looking forward to letting this baby rip at LDRS!
Initial check and preparation.
Greased O-rings and assembled forward bulkhead.
You're gonna love that motor!
i had the same issue with a J350 that spelled disaster for my cert 2 flight back in 98'. ever since then i put a good coat of Dow 111 grease around the delay insulator. no problems since.
I saw the M2200X pics from LDRS 38 on your Facebook page. Any estimate when this will be available?
I'm really looking forward to seeing the thrust curve too... How does it compare with the M1297 for total impulse?
Here is what they posted about it. 5498 total impulse
First time loading my new 24/60 motor and the propellant liner gets about halfway in the case and now is completely stuck. I always lightly lube the inside of my cases just to ease assembly and cleanup.
I finally removed it after cutting it out of the motor. So now I'm short a liner for a reload kit. Upon closer inspection, there is an area inside the case where the ID of the case changes, mabe 10mm or so from each end of the case. Before I go peeling the outer layer of the liner off, is this normal on the 24/60 or did I get a bum case?
Quality control issues?
AT got back to me and said it is actually by design to help the nozzle seat. But they said there was no issue with peeling off the outer layer of the liner like in the HP loads to make it fit. They're sending me a replacement liner in the mail.
I had the exact same issue. I attempted to load an F63 and also destroyed the liner. I contacted Aerotech and they replaced my case and liner.
Are there any plans for a 54 or 75 mm stainless steel seal disk? With the hotter loads AT has been putting out (read: ST and X), it seems my aluminum disks aren't lasting as long...
On a similar note, provided that the o-ring sealing surface on a seal disk isn't scratched, pitted, or otherwise compromised, are there any issues with flying beat-up seal disks? What should we be looking for that would indicate that it is time to replace?
Even though it is not on thrustcurve.org yet (we miss you Mark!) the green label from Chris Short shows the M2200X motors thrust curve with a 2.5 second burn
I want to be first in line for this ! Push the CFM approval !!
It hasn’t been certified by Tripoli TMT yet. It was just sent to them one week ago today.
The bottom line item "O5280X" caught my eye. A 22k Ns disposible 98mm...I can't wait to see the confetti production flight attempts like the first years of the N5800.
That L462NW has me intrigued also.
My 24/60 cases (all of them) have always been like that from AT. Seems like a few others might have been that way too, but I just can't recall. I always thought it was strange that the milling of the inside of the case could be so "off", especially when I flew those cases a lot, but these days, I just don't worry about it in that size motor...
So I flew my first DMS today and really enjoyed it. I have always been a reload kind of guy ever since I started flying AT motors but lately I have been looking for the quick and easy. I flew a G72DM and what a treat it was. Super easy to prep for flight and the motor performed admirably. I will be flying more in the future for sure as I really enjoyed it.
Has anybody heard when the new aerotech rocket is coming out. I saw it in the Sport rocketry magazine and I think it's called the mega initiator with a 54 mm motor mount.
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