AeroTech Open Thread

I'll be flying an L1090 (RMS version) at GHS this year. I'm glad I ended up with the RMS version, especially now that they've got another reload for that case.

cerving said:

They ship them with the thrust rings off, you have to glue them on now. Even if they're on, it doesn't hurt to add a little CA as a backup. More troubling to me is the forward closures... I had two flights at LDRS with them, and both of them blew out the forward closures. The first one blew right away, reaching an apogee of about 1,000' instead of 11,000', and was forceful enough that it blew the guts out the back and took the Aeropack screw-on cap with it. The rocket had a solid builkhead in front of the motor mount, so fortunately it did no damage to the rocket. Since AT was on-site, we gathered up the pieces and brought them to their table, they gave me a replacement.

The replacement went all the way to 11,600', and I was quite satisfied... until I got home and took out the motor. Seems the forward closure had actually let go, but apparently it was late enough that it didn't have a significant effect on the flight. I'm done with the L1000 DMS... at least until I see an actual advisory from AT that they've fixed the forward closure issues, which seems to be why they're failing now.

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I had an L1000 DMS from one of the first few production runs (lot code 101074) that was recalled. I coordinated with Balsa Machining and Aerotech, and a replacement was sent to me from Karl Baumann in June of last year.

If there have been recalls on the L1000 manufactured after that, then I would like to know. I do not want to fly an L1000 that is not reliable.

I have not opened the replacement to examine it to see if the thrust ring is attached or not.

dshmel said:

If there have been recalls on the L1000 manufactured after that, then I would like to know. I do not want to fly an L1000 that is not reliable.

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Just glue fins on it and let 'er rip!

djs said:

Who would accept payment in reloads?

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This is actually the key to the whole thing

markkoelsch said:

Do it in Mojave Green. A single use in that, assuming it holds together, could be awesome.

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A Green DMS would be sweet for sure, not sure where we are on that currently though.

watermelonman said:

With all the attention 4-to-3-inch two stagers get, the lack of an extra long 75mm is a bummer. For some bizarre reason Cesaroni only ever offered one performance motor in that size, and now it is literally unobtainable.

Loki may fill that gap, but I am curious if simply stuffing an extra grain on top of an M685 would be a benefit.

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Eric,

See the post #1187 above regarding a possible 75/10240.

mikec said:

Oops, I left off the 38mm SU motors. The big 98mm ST motors were on the earlier list.

My understanding based on the ad in the last Sport Rocketry is that there are other ST motors in the pipeline, like a 54mm one, but those aren't on thrustcurve yet.

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You are correct, Mark has been in touch with us and I believe we have supplied him with the info for all of the newly certified motors.

watermelonman said:

Some folks were flying 29mm single use demo motors at XPRS, maybe an F67, faster white lightning?

Any specific details on the motor or idea what the plan is for that one?

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The F67 is under development and uses the Super White propellant. This will be sold in a 2-pack, probably as an economax motor. We are also developing a DMS J motor with the same propellant so you should see more of this in the field next year.

markkoelsch said:

I have some of the data for the new motors. I might get to it one of these day. His is what happens when one works 12-14 hours a day for a bit.

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Thanks Mark, we appreciate it.

crossfire said:

Charlie

Gerald has a picture of your AT tent at Black Rock. On one of the tables there is what looks like a 3" single use motor? What is it?

Thanks
Gary

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Gary,

That is the recently certified 98mm DMS M1340W. It is essentially a single-use M1419W. The one in the photo was fired the previous week during XPRS.

djs said:

Charlie- will you or someone else from AT be at Midwest Power this year?

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I was really trying to get up there again but I don't think I can pull it off this year. Had such a great time last year too.

GRIFFIN said:

Keep in mind, that answer HAS to be YES. Since we are flying uncertified motors in the drag race. The motor manufacturer NEEDS to be present.

See you there. I'll save you a seat at the Pizza party!

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Jason,

The motors have been certified so I don't necessarily have to be there...but I still want to go. Just have too much going on right now, including the sadness of missing the pizza party.

GRIFFIN said:

Mark!!! This was how I was going to trick Charlie into having to make the trip!!

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That is a sound strategy, I like it!

djs said:

Maybe Charlie wants to enter into the drag race? Or he could demo the new 29/40-120 reloads that are supposedly coming out (red and metalstorm)?

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You guys are making this launch difficult to resist.

terryg said:

I am confused, is the K990dm a reload for the 2800 case or a single use? It's total impulse appears to be less then the K850dm for the shorter 2560 case.

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Yeah, it looks like there were a few errors on the TMT announcements, we are working on official announcements now for 10 new motors.

grouch said:

Cool. I'll be here when you do. Any chance of getting a 29mm Super Thunder? By the way, I flew my first Metalstorm today and I can tell you it won't be my last. What a ride. Loud, fast, bright, sparkie...what's not to love?

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I think as we begin to get into the 29mm lines ST would be a natural fit. Really glad you enjoyed the metalstorm!

ATGM said:

You guys are making this launch difficult to resist.

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This post is definitely not to trash AT. I simply want to know if anyone has any input as to why this may have happened. I know the 29mm G71R-7 is an old motor, but I've launched three of them prior to today and never had a problem. Bad delay grain, ignitor not installed all the way, or maybe even grease on the delay grain? I have no idea. If anyone can share some input, I'd appreciate it. Thanks! https://youtu.be/qKD2t6Jl3mQ

noffie79 said:

This post is definitely not to trash AT. I simply want to know if anyone has any input as to why this may have happened. I know the 29mm G71R-7 is an old motor, but I've launched three of them prior to today and never had a problem. Bad delay grain, ignitor not installed all the way, or maybe even grease on the delay grain? I have no idea. If anyone can share some input, I'd appreciate it. Thanks! https://youtu.be/qKD2t6Jl3mQ

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I cant watch at work, but you'll get more visibility with a new thread. Also fill out a MESS report https://www.motorcato.org/ and let Aerotech know for a warranty claim.

ATGM said:

You guys are making this launch difficult to resist.

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If you don't come to MWP, I swear I'm not buying another AT motor for at least a week!

Kallahan11 said:

I cant watch at work, but you'll get more visibility with a new thread. Also fill out a MESS report https://www.motorcato.org/ and let Aerotech know for a warranty claim.

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I did do a new thread. I'll fill out a MESS report tonight and I'll let AT know. Thanks!

watermelonman said:

I believe I flew the first ever certified K2050 in my Nike Smoke yesterday at TCC October Skies -

It was spectacular. More later.

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Awesome pic! Must...get...original...from...Eric.

markkoelsch said:

For those that have not seen it. Aerotech has put out a grain glueing advisory for certain 75 and 98 mm motors.

https://www.aerotech-rocketry.com/news.aspx?y=2016#n2172

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Thanks for the link Mark, I will go ahead and post the text of it shortly if it has not been done already.

djs said:

Speaking of the L1000- are the thrust rings ok on these now? Thinking of picking one of these up at some point.

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Good question here, thanks. Yes, ALL DMS motors come with an installed thrust ring now. The 54mm rings are 3d printed and epoxied in with the nozzle as they snap around the case. A small bead of CA is ran underneath afterwards and they are set. The 54mm tested to over 1800 lbs and still didn't fail.

cerving said:

They ship them with the thrust rings off, you have to glue them on now. Even if they're on, it doesn't hurt to add a little CA as a backup. More troubling to me is the forward closures... I had two flights at LDRS with them, and both of them blew out the forward closures. The first one blew right away, reaching an apogee of about 1,000' instead of 11,000', and was forceful enough that it blew the guts out the back and took the Aeropack screw-on cap with it. The rocket had a solid builkhead in front of the motor mount, so fortunately it did no damage to the rocket. Since AT was on-site, we gathered up the pieces and brought them to their table, they gave me a replacement.

The replacement went all the way to 11,600', and I was quite satisfied... until I got home and took out the motor. Seems the forward closure had actually let go, but apparently it was late enough that it didn't have a significant effect on the flight. I'm done with the L1000 DMS... at least until I see an actual advisory from AT that they've fixed the forward closure issues, which seems to be why they're failing now.

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Both of these issues have been resolved. If you have an L1000 let go be sure to at least send us the date codes on the tube so we can verify that it was indeed one of the older ones. My guess is that it is since the redesigned ones have not had any reported issues.

Also all DMS motors ship with installed thrust rings, though the 54mm were being shipped without them for a period of time.

ATGM said:

Both of these issues have been resolved. If you have an L1000 let go be sure to at least send us the date codes on the tube so we can verify that it was indeed one of the older ones.

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Thanks for the info! Could you tell us when the "good ones" started being produced, so I can check something before I buy?

noffie79 said:

This post is definitely not to trash AT. I simply want to know if anyone has any input as to why this may have happened. I know the 29mm G71R-7 is an old motor, but I've launched three of them prior to today and never had a problem. Bad delay grain, ignitor not installed all the way, or maybe even grease on the delay grain? I have no idea. If anyone can share some input, I'd appreciate it. Thanks! https://youtu.be/qKD2t6Jl3mQ

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The G71R was a little before my time so I am not sure what the exact issue was but I think there was a delay issue so we stopped making them. Maybe other TRF members can recollect better than I can but it was something like that. That is why a new red load for the 29/40-120 is such a highly requested load. We are developing new loads for the hobby line now and a red to replace the G71R is on the list.

djs said:

If you don't come to MWP, I swear I'm not buying another AT motor for at least a week!

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The bosses have to let me go now!

djs said:

Thanks for the info! Could you tell us when the "good ones" started being produced, so I can check something before I buy?

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I'll get with Karl and see if he can provide me some info that can help with that.

75 & 98mm RMS™ Reload Kit Grain Bonding Advisory


10/20/16


Dear AeroTech/RCS Dealers and Customers,


Over the past 26 years we have accumulated and examined a great deal of in-house test data
and customer field experience with the RMS Reloadable Motor System™. In addition, the
development of new products such as the recently-released Super Thunder™ 98mm reloads
have required us to test the limits of the system, pushing it to generate performance numbers
previously unheard of from AeroTech products.


During this testing, development and use we have discovered certain motor configurations that
have benefitted from bonding the propellant grains into the liner prior to firing to achieve
enhanced reliability. Not only does it prevent movement of the grains toward the nozzle during
acceleration and the differential chamber pressure experienced during startup (which can cause
a CATO if the aft propellant grain collapses under pressure and plugs the nozzle), it appears to
greatly reduce instances of “tunneling” where hot gases penetrate the spiral gaps in the
propellant casting tubes, causing the propellant to burn on the outside of the grain that is
normally inhibited by the tube.


Therefore, we are advising all our customers to bond the grains of the following reload kits into
their liners with Elmer’s Glue-All Max™. This is a polyurethane glue with minimal foaming and
expansion to prevent the liner from cracking during cure, and has a long working time. The
bonding process itself takes only a few minutes after which the glue should be allowed to cure
overnight before use.


The reload kits affected by this advisory are:


75mm
K1000T, L1520T, L2200G, M1500G, M1780NT


98mm
L1500T, M2400T, L2500ST, M4500ST, M1845NT, M2100G, M2500T, M2000R, M6000ST,
N2000W, N3300R, N2200DM


If you have any of these reload kits in your possession, we strongly advise you to bond the
grains into the liner prior to flight for maximum reliability. All new production lots of these reload
kits will now include a copy of the grain bonding instructions along with the standard assembly
instructions.


A copy of the grain bonding instructions are included with this advisory and will be posted on the
AeroTech website in PDF format.


Your understanding is appreciated, and we thank you for your continued support!