AeroTech Open Thread

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@AeroTech I have procured two 54mm grains/sticks of slow white lightning through my local vendor. Both are labeled as slow white lightning, but while one is 16.25" in length, the other is 18.5" in length (does not match description on the RCS website). Have you guys standardized the size of 54mm sticks, or should I be concerned about the delta?
 

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eJar0k said:
Of the two burns in the M2700W TMT cert document, which is closer to an average burn? I remember an earlier test putting out around 10300Ns, so I'm guessing we should use the 10600Ns one, right? Surprised they performed so differently.

By the way, it looks like that motor atop an O5500 could crack 100km... and Mach 5.
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Average was 10,322. Yes, that’s the idea. 😁🚀
 
emckee said:
@AeroTech I have procured two 54mm grains/sticks of slow white lightning through my local vendor. Both are labeled as slow white lightning, but while one is 16.25" in length, the other is 18.5" in length (does not match description on the RCS website). Have you guys standardized the size of 54mm sticks, or should I be concerned about the delta?
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We have been casting longer sticks on some batches so I would consider it a bonus.
 
AeroTech said:
Thanks for the suggestion. This would be doable with our new phenolic nozzle inserts.
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I agree, I’m flying a hot-rodded Quest Courier (BT-55 extension tube, one-piece recovery, altimeter bay, 29mm mount and Labyrinth system, beefy stand-off for 1010 rail buttons, Estes retainer) and the E30 is a bit too much impulse for the 1000ft ceiling at the home field, but the E26 seems to make it prone to weathercocking and I suspect that the issue is the flatter thrust curve. I think getting the initial spike down to about 75% of the E30 with the thrust profile and duration otherwise similar would be a winning combo for that rocket in particular. I don’t have any particular propellant preference but I suspect that some kind of Blue Thunder or Redline ought do it.

As always, take that how you will, I’m just one guy with one potential use case.
 
smstachwick said:
I agree, I’m flying a hot-rodded Quest Courier (BT-55 extension tube, one-piece recovery, altimeter bay, 29mm mount and Labyrinth system, beefy stand-off for 1010 rail buttons, Estes retainer) and the E30 is a bit too much impulse for the 1000ft ceiling at the home field, but the E26 seems to make it prone to weathercocking and I suspect that the issue is the flatter thrust curve. I think getting the initial spike down to about 75% of the E30 with the thrust profile and duration otherwise similar would be a winning combo for that rocket in particular. I don’t have any particular propellant preference but I suspect that some kind of Blue Thunder or Redline ought do it.

As always, take that how you will, I’m just one guy with one potential use case.
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Actually, just today I could have used several 25-30 Ns high thrust motors
I ended up using D15, because they lifted the rockets with reasonable authority. Just not very high....

Edit: I had an E30 in the motor box, it could have worked, but the wind was too high.

Hans.
 
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AeroTech said:
Thanks for the suggestion. This would be doable with our new phenolic nozzle inserts.
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It would be great if you started phasing in the phenolic inserts in all the Q-jets D and larger, as I have still been having issues with nozzle material spalling off and causing misaligned thrust with D16s, D20s, and E35s.
 
AeroTech said:
RMS-75/10240 M2700W-PS TRA certification. This motor was developed for the upcoming $10,000+ AeroTech Space Challenge contest.
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So, when are you gonna make the Propellant-X load for this case? :-D

Also, what ever happened to the N4800 from ~18 years ago? I believe it was a near full N 98mm blue thunder
 
Hello. I made a post in the HPR forum about machining down the aft closure thrust ring OD to match the motor tube OD and someone linked me to this post.

https://www.rocketryforum.com/threads/aerotech-open-thread.125657/post-2044762

My desire is to use the motor as part of my interstage for a 2 stage project so the motor would be sticking out of the back of the sustainer by X inches in order to fit into the booster coupler. Can you confirm whether or not machining down the aft closure thrust ring in order to match the motor tube OD would constitute an experimental motor?
 
khabuka: You don't need aerotech to tell you that modifying part of the motor, and not using it as certified makes it a experimental motor. Stop looking for a loophole.
 
khabuda said:
Hello. I made a post in the HPR forum about machining down the aft closure thrust ring OD to match the motor tube OD and someone linked me to this post.

https://www.rocketryforum.com/threads/aerotech-open-thread.125657/post-2044762

My desire is to use the motor as part of my interstage for a 2 stage project so the motor would be sticking out of the back of the sustainer by X inches in order to fit into the booster coupler. Can you confirm whether or not machining down the aft closure thrust ring in order to match the motor tube OD would constitute an experimental motor?
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I'm the one who sent you to that other thread. That is the only example I'm aware of of an AeroTech-approved case where removing a thrust ring is OK.

If you did some more searching (only takes a few minutes) on the subject of machining factory closures, you'd find a consensus that it is not approved and therefore "experimental."

Someone else pointed you to Loki hardware. I posted a link in your other thread. That is your only option for reloadable hardware, AFAIK.
 
cbrarick said:
khabuka: You don't need aerotech to tell you that modifying part of the motor, and not using it as certified makes it a experimental motor. Stop looking for a loopho
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SolarYellow said:
I'm the one who sent you to that other thread. That is the only example I'm aware of of an AeroTech-approved case where removing a thrust ring is OK.

If you did some more searching (only takes a few minutes) on the subject of machining factory closures, you'd find a consensus that it is not approved and therefore "experimental."

Someone else pointed you to Loki hardware. I posted a link in your other thread. That is your only option for reloadable hardware, AFAIK.
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Fair enough. I am new to all of this, so I honestly don't know. I will shift my question to Loki directly.
 
khabuda:

You asked and got your question answered in your other thread. Going to another thread to ask the exact same question is akin to when my son was small and didn't get the answer he wanted from his mother. His next ploy was to ask me. Not cool.

Loki will be of no help. Same issue. If you look at the latest (Loki cocktail) instructions https://lokiresearch.com/images/Documents/38mm Cocktail Aug 2019.pdf it specifies a "motor case with thrust ring" so no dice.

my suggestion is to ask what others are doing. you may find that much more fruitful. It very well may be that grinding down the closure and then flying it at a EX launch is the best solution. This will only require you to pony up for a Tripoli membership. Even if you found someone who would tell you it's ok, you're gonna have significant problems with RSO. Don't forget they are the last word, despite permission from third parties. The RSO is responsible that the rocket in question meets the applicable safety code, and their decision is final.
 
Art Upton said:
Since when was simply removing the thrust ring from an AMW or Loki motor a motor modification? It's a snap ring made to be able to be replaced at will.

Ask Loki and see what Scott has to say.
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I did email him. He said it was common and thought it was a okay as long as you keep the aft end pointing toward the aft end. Got some real curmudgeons in here it seems. It's just big toys boys.
 
khabuda said:
It's just big toys boys.
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While I agree it's pretty obvious that removing the thrust ring from a Loki motor (which is just a spiral retaining ring that fits into an external groove on the case) would not interfere with the safe operation of the motor, I would advise against having too cavalier an attitude towards rocket motors.
 
I agree that the motor will work ok without the thrust ring. The question is wither it would work, but is it a modification. NAR rules do not allow modifications. From the NAR HIgh Power safety code "Motors. I will use only certified, commercially made rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer. I will not allow smoking, open flames, nor heat sources within 25 feet of these motors."
the rule just doesn't allow for interpretation. Use them as the motor manufacture directions call for or they don't pass the test. They do not say that it's not tampering if person x thinks it will work fine." That's why my post had a link to the Cocktail motor instructions.

I don't understand the push-back. The simple solution is still to pull a Tripoli membership and fly them at a Tripoli event as a EX motor. I don't understand why that's so difficult.
 
cbrarick said:
I agree that the motor will work ok without the thrust ring. The question is wither it would work, but is it a modification. NAR rules do not allow modifications. From the NAR HIgh Power safety code "Motors. I will use only certified, commercially made rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer. I will not allow smoking, open flames, nor heat sources within 25 feet of these motors."
the rule just doesn't allow for interpretation. Use them as the motor manufacture directions call for or they don't pass the test. They do not say that it's not tampering if person x thinks it will work fine." That's why my post had a link to the Cocktail motor instructions.

I don't understand the push-back. The simple solution is still to pull a Tripoli membership and fly them at a Tripoli event as a EX motor. I don't understand why that's so difficult.
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It's not difficult. I was trying to get multiple points of feedback to make a properly informed decision.
 
cbrarick said:
I agree that the motor will work ok without the thrust ring. The question is wither it would work, but is it a modification. NAR rules do not allow modifications. From the NAR HIgh Power safety code "Motors. I will use only certified, commercially made rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer. I will not allow smoking, open flames, nor heat sources within 25 feet of these motors."
the rule just doesn't allow for interpretation. Use them as the motor manufacture directions call for or they don't pass the test. They do not say that it's not tampering if person x thinks it will work fine." That's why my post had a link to the Cocktail motor instructions.

I don't understand the push-back. The simple solution is still to pull a Tripoli membership and fly them at a Tripoli event as a EX motor. I don't understand why that's so difficult.
Click to expand...

Bold, red added above. That's the key point. You can make changes to the motors if they are approved by the manufacturer without interfering with the certification of the motor. This is an opportunity for manufacturers to allow small changes like leaving off a thrust ring if the motor is otherwise retained. Likewise, Aerotech said in post #3724 that sanding down a thrust ring on a DMS motor is acceptable. I've seen similar guidance from CTI on 38mm thrust rings--that they can be turned down to the motor casing OD if desired. I trust that all of our hobby motor manufacturers are looking out for us and them enough to not approve things that could go sideways.

Many things are possible with manufacturer approval. It's definitely worth checking with the club and RSO if known.
 
boatgeek said:
I've seen similar guidance from CTI on 38mm thrust rings--that they can be turned down to the motor casing OD if desired.
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Is that in writing somewhere? I'd love to have it on file. Maybe reply in the CTI thread, to avoid cluttering up AT's thread with additional discussion of competitor product.
 
Well, as has been noted elsewhere, you could obtain the boat-tail closures that exist for certain motors (I believe @cbrarick may have some to sell you :) ), which were made for minimum diameter installations and don't have a thrust ring, and, voila, you have an unmodified, manufacturer motor with no thrust ring!
 
IMG_2268.jpegIMG_2267.jpeg


Gotta say…getting the smoke grain liner out of a 75mm forward closure is a real PITA. Anyone have any ideas to make this a little easier then how I do it? This was a L1940 reload BTW….
 
DAllen said:
View attachment 642389View attachment 642390


Gotta say…getting the smoke grain liner out of a 75mm forward closure is a real PITA. Anyone have any ideas to make this a little easier then how I do it? This was a L1940 reload BTW….
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I've never gotten one stuck. Was it greased before install? Maybe heat it up and see if it'll pop loose?
 
DAllen said:
View attachment 642389View attachment 642390


Gotta say…getting the smoke grain liner out of a 75mm forward closure is a real PITA. Anyone have any ideas to make this a little easier then how I do it? This was a L1940 reload BTW….
Click to expand...
Use a sharp pick to stick in one side of the liner twards the top on the inside almost perpendicular and pry/pull up. If it's still stuck run it under hot , hit water till the aluminum grows and try again.
 
boatgeek said:
Bold, red added above. That's the key point. You can make changes to the motors if they are approved by the manufacturer without interfering with the certification of the motor. This is an opportunity for manufacturers to allow small changes like leaving off a thrust ring if the motor is otherwise retained. Likewise, Aerotech said in post #3724 that sanding down a thrust ring on a DMS motor is acceptable. I've seen similar guidance from CTI on 38mm thrust rings--that they can be turned down to the motor casing OD if desired. I trust that all of our hobby motor manufacturers are looking out for us and them enough to not approve things that could go sideways.

Many things are possible with manufacturer approval. It's definitely worth checking with the club and RSO if known.
Click to expand...

Correct, drilling motor delays is modifying a motor. When it was recommended by the manufacture, it is not. Now it has become common place that is is finally in instructions and tools provided.
 

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