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Tractionengines

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Why not bring back the phenolic cased SU version like they used to be. Then you don't have to worry about losing an expensive case.

I agree, but I think that original case is OOP, and is the reason for a number of old motors being retired.

Shipping it as a SU version would still be hazmat. Unless they made it a loadable SU, and shipped the propellant as 2 grains. (The LMS motors don't seem to fly off the shelves, so making this into one is very unlikely.) That would also make costs higher.

Maybe there's a chance; if the NEW G8 and G12 have strong sales, then maybe they bring out a new G25 variant. (IF it would work as just a propellant and minor nozzle change on that even better. ) As LPR flyers best way to get options is to use the new ones they did come out with.

Just my 2 cents.
 

AeroTech

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We discussed the G25 bifurcated grain idea and the spacer for the 29/60 and 29/100 reloads and unfortunately the sales for all those motors COMBINED is only about 1 tenth of one percent of our business. We cannot justify the investment in time and materials for that. Additionally, bifurcating the G25 grain would result in two grains that would still require hazmat shipping. The overall propellant weight (and performance) would need to be reduced, new instructions and labels created, and the motor re-certified with all the changes. It's just not worth it for a motor that sells only a few units per year.
 

DeltaVee

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We discussed the G25 bifurcated grain idea and the spacer for the 29/60 and 29/100 reloads and unfortunately the sales for all those motors COMBINED is only about 1 tenth of one percent of our business. We cannot justify the investment in time and materials for that. Additionally, bifurcating the G25 grain would result in two grains that would still require hazmat shipping. The overall propellant weight (and performance) would need to be reduced, new instructions and labels created, and the motor re-certified with all the changes. It's just not worth it for a motor that sells only a few units per year.
Oh well... thank you for bringing it up...
 

AeroTech

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I agree, but I think that original case is OOP, and is the reason for a number of old motors being retired.

Shipping it as a SU version would still be hazmat. Unless they made it a loadable SU, and shipped the propellant as 2 grains. (The LMS motors don't seem to fly off the shelves, so making this into one is very unlikely.) That would also make costs higher.

Maybe there's a chance; if the NEW G8 and G12 have strong sales, then maybe they bring out a new G25 variant. (IF it would work as just a propellant and minor nozzle change on that even better. ) As LPR flyers best way to get options is to use the new ones they did come out with.

Just my 2 cents.
The G12 construction style for a SU G25 has merit, however again there is the issue of extremely low sales for that motor not justifying the effort.
 

StreuB1

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One of the many things I love about AT, is that they listen to us. Even those of us that use something that is less than 1% of their sales, and they talk about it at a high level, look at numbers, and see if it makes sense. And when it doesn't, they come back and tell us and give us the honest reasons why. They never [intentionally] ignore us and they go out of their way at times to make sure they are always hearing us.

Rare for companies these days to do that.

I have 98mm AT hardware and loads coming from Tim from the past sales and I can tell you this. It's been since I was a teenager (now 44) that I've wanted 98mm AT stuff. Now, I'm getting it, and thats cool to me. 🙃
 

Tractionengines

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+1 ON THE LISTENING AND GIVING FEEDBACK FOR REQUESTS. As a Businesses Development Manager I always say send me ALL your requests; I will say NO a lot. But if your not asking, I don't know what your looking for. Open communication is a GREAT thing.

Also, +1 on the G25 SU... [ Actually any thrust level between G20 to G30...whatever fits in a new/existing 29mm SU cases with existing propellant to keep development cost down.] That size splits the difference between the new G12 and the next size up G40... enough push to lift stuff too heavy for the G12, and not just disappear off the pad or overstress airframes (ie. Estes PSII stuff) like a G40/G7x/G80.

Mike
 

Rocketjunkie

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Yes, all the G and higher power endburners do.
Unfortunately that eliminates the Maniac/Eliminator 'fire and forget' flights. Just like making the G25 a reload - expensive case. A G25-10 in a Maniac was the perfect demo for school launches. Haven students were still talking about it 3 years later :) (G40s usually shreded a Maniac or Eliminator. (Same rocket, different decals.))
 

MichiganJohn

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Looking for some insight on why this K185 may have burned in this manner. This was assembled in late-April but then couldn't launch - it was stored in a cool dry location until I could fly it in early November. I'm very meticulous in following assembly instructions, but also relatively new to high power so could have potentially made a mistake along the way. Any insights appreciated - want to make sure I eliminate any user error going forward. Thanks.
 

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3stoogesrocketry

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Looking for some insight on why this K185 may have burned in this manner. This was assembled in late-April but then couldn't launch - it was stored in a cool dry location until I could fly it in early November. I'm very meticulous in following assembly instructions, but also relatively new to high power so could have potentially made a mistake along the way. Any insights appreciated - want to make sure I eliminate any user error going forward. Thanks.



I do not see a single thing wrong with the way that motor looks . It is a moon burner so it will burn the casting tube one side more then the other . The liner did its job . Alot of thermal heat happens post burn from the delay grain .
 

MichiganJohn

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I do not see a single thing wrong with the way that motor looks . It is a moon burner so it will burn the casting tube one side more then the other . The liner did its job . Alot of thermal heat happens post burn from the delay grain .
Thanks for the feedback. When it came off the rail flying in a Tomach 54, it started to corkscrew and flew at ~45deg angle to ground. The rocket had had a previous successful flight on different motor and didn't have any noticeable damage to the structure afterward (no lost fins, etc). I did use an aluminum tailcone retainer on this flight - it got very hot and the aft end had some melting. So I assumed the overall effect had something to do with the engine or nozzle (which appears to have a lot of cracking/crazing), and I wasn't sure if that was normal. Appreciate the response.
 

Tractionengines

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I want to try my Turbo Vortico oddrock with the G12 and H13, should be fun.
I have been thinking the same thing, but not sure if the length/weight of the motor will upset the stability. It's a small rocket, but first time will be from an away cell for sure.... if someone else tries this please let us know how it works. Will be either a very cool 13-15 second burn. Or a very interesting 13-15 seconds waiting for it to burn out...
 

3stoogesrocketry

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Thanks for the feedback. When it came off the rail flying in a Tomach 54, it started to corkscrew and flew at ~45deg angle to ground. The rocket had had a previous successful flight on different motor and didn't have any noticeable damage to the structure afterward (no lost fins, etc). I did use an aluminum tailcone retainer on this flight - it got very hot and the aft end had some melting. So I assumed the overall effect had something to do with the engine or nozzle (which appears to have a lot of cracking/crazing), and I wasn't sure if that was normal. Appreciate the response.

This is a semi common ( more so with three fin rockets then four ) problem with moon burning motors . The mass of the motors propellent is offset to one side to get the long burn . Try it again with a K550. Same propellent , just in a Bates grain formate .
 

MichiganJohn

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This is a semi common ( more so with three fin rockets then four ) problem with moon burning motors . The mass of the motors propellent is offset to one side to get the long burn . Try it again with a K550. Same propellent , just in a Bates grain formate .
Thanks for explaining - I can envision the potential for that particularly with a minimum diameter rocket. I'll look at the K550 as an option in the future.
 

tjsnakez

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Thanks for the feedback. When it came off the rail flying in a Tomach 54, it started to corkscrew and flew at ~45deg angle to ground. The rocket had had a previous successful flight on different motor and didn't have any noticeable damage to the structure afterward (no lost fins, etc). I did use an aluminum tailcone retainer on this flight - it got very hot and the aft end had some melting. So I assumed the overall effect had something to do with the engine or nozzle (which appears to have a lot of cracking/crazing), and I wasn't sure if that was normal. Appreciate the response.

Are you talking about a tailcone retainer like an Aeropack, or a tailcone aft closure? You cannot use a tailcone aft closure with any medusa nozzle motors or a situation like what you describe will happen. The nozzle being recessed inside the tailone does not provide area for the exhaust plume as the gasses exit the nozzle. Although the nozzle cracking/crazing does not look normal to me - If you are indeed referring to a retainer and not a closure I would say there is some sort of motor issue.
 

MichiganJohn

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Are you talking about a tailcone retainer like an Aeropack, or a tailcone aft closure? You cannot use a tailcone aft closure with any medusa nozzle motors or a situation like what you describe will happen. The nozzle being recessed inside the tailone does not provide area for the exhaust plume as the gasses exit the nozzle. Although the nozzle cracking/crazing does not look normal to me - If you are indeed referring to a retainer and not a closure I would say there is some sort of motor issue.
Yes, I used a tailcone aft closure. I wasn't familiar with the medusa nozzle and didn't know to avoid the pairing - thanks for confirming.
 

tjsnakez

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Yes, I used a tailcone aft closure. I wasn't familiar with the medusa nozzle and didn't know to avoid the pairing - thanks for confirming.

No problem! It could have been a lot worse it sounds like. The aerotech tailcone closures are a relatively new thing, I feel like there could be more warning regarding it's usage with medusa nozzles. It seems fairly obvious, but it is definitely something that can be overlooked.
 

AeroTech

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Thanks for the feedback. When it came off the rail flying in a Tomach 54, it started to corkscrew and flew at ~45deg angle to ground. The rocket had had a previous successful flight on different motor and didn't have any noticeable damage to the structure afterward (no lost fins, etc). I did use an aluminum tailcone retainer on this flight - it got very hot and the aft end had some melting. So I assumed the overall effect had something to do with the engine or nozzle (which appears to have a lot of cracking/crazing), and I wasn't sure if that was normal. Appreciate the response.
The fired reload parts look completely normal to me. But tailcone retainers won’t work with Medusa nozzles.
 

n3tjm

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I know you said it will cost to much for redocumentation and possible recertification, but would a 3 grain G25 work? Epoxy three grains together instead of two.
 

boatgeek

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I had a failure of an [edit] E18-7 [end edit] motor in a 24/40 case this weekend. It was an old (~10-15 years!) reload, and the grain was prettty swollen. I trimmed out some of the oxidation where the igniter lands, and managed to get it all together. It took some force to screw down the aft closure. I also declined to use the included copperhead starter, and instead used a Firstfire Micro boosted with a little Duco and black powder. Ignition was slow, with a couple of chuffs, including one with the rocket about 2/3 of the way up the rail. Off the pad and up in the air, the motor came up to pressure and spat the aft closure and nozzle. On recovery, the case has a notch cut out in line with the C-slot and the anodizing on the case is burned back 1/4" or so from the case end. Here's what it looks like:
IMG_3780.JPG


So my questions:
(a) Did I do something wrong in the assembly? It looks like the aft o-ring failed. I followed the instructions to the best of my ability, but I can't discount the possibility of user error.
(b) Is this kind of failure covered by warranty?
(c) I have several other aged reloads like this one, in D to H ranges, that were left to our local high school rocketry club. Are we going to continue to have issues like this with these reloads? If so, I'm inclined to consign them to household hazardous waste rather than risk destruction of student rockets.

More info and flight video here:
 
Last edited:

AeroTech

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I had a failure of an E8-7 motor in a 24/40 case this weekend. It was an old (~10-15 years!) reload, and the grain was prettty swollen. I trimmed out some of the oxidation where the igniter lands, and managed to get it all together. It took some force to screw down the aft closure. I also declined to use the included copperhead starter, and instead used a Firstfire Micro boosted with a little Duco and black powder. Ignition was slow, with a couple of chuffs, including one with the rocket about 2/3 of the way up the rail. Off the pad and up in the air, the motor came up to pressure and spat the aft closure and nozzle. On recovery, the case has a notch cut out in line with the C-slot and the anodizing on the case is burned back 1/4" or so from the case end. Here's what it looks like:
View attachment 495717

So my questions:
(a) Did I do something wrong in the assembly? It looks like the aft o-ring failed. I followed the instructions to the best of my ability, but I can't discount the possibility of user error.
(b) Is this kind of failure covered by warranty?
(c) I have several other aged reloads like this one, in D to H ranges, that were left to our local high school rocketry club. Are we going to continue to have issues like this with these reloads? If so, I'm inclined to consign them to household hazardous waste rather than risk destruction of student rockets.

More info and flight video here:
I assume you mean a D9 or an E28 as there is no E8. It seems to me to be an assembly error of some type. Never seen that exact type of failure before. Motors and reloads are warrantied for specific conditions and modes for 5 years after their date of manufacture, so that incident would not be covered under warranty.
 
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