G69 end burner question

[rstaff3]

This may be a question for AeroTech but since there are so many motor people here now....

I flew one of the new Warp-9 end burners in my Hat of Death. When I went to clean the casing, I noticed the liner was completely burned away at the nozzle end and and the finish inside looks discolored. I've never seen this on any of my AT cases. It makes sense as the flame is on the lower end during the whole burn. My question is whether this will eventually damage the case?

 

[ben]

Originally posted by rstaff3
This may be a question for AeroTech but since there are so many motor people here now....

I flew one of the new Warp-9 end burners in my Hat of Death. When I went to clean the casing, I noticed the liner was completely burned away at the nozzle end and and the finish inside looks discolored. I've never seen this on any of my AT cases. It makes sense as the flame is on the lower end during the whole burn. My question is whether this will eventually damage the case?

that was an endburner? Looks like I might need to get one

Ben

 

[jsdemar]

Originally posted by rstaff3
This may be a question for AeroTech but since there are so many motor people here now....

I flew one of the new Warp-9 end burners in my Hat of Death. When I went to clean the casing, I noticed the liner was completely burned away at the nozzle end and and the finish inside looks discolored. I've never seen this on any of my AT cases. It makes sense as the flame is on the lower end during the whole burn. My question is whether this will eventually damage the case?

Yes, this is the reason you don't normally see reloadable endburners. You should probably report this to Aerotech and TMT as a design flaw.

I've made several EX endburners over the years (from 12mm composite B's on up). The propellant needs to be fast and the case/liner combo needs to be thick. Aerotech's got one of the two right, it seems.

-John

 

[bobkrech]

That's a good question. It could simply be the pigment used to color the anodization is burning up, or it could be more serious. If the casing temperature gets much over 200C the aluminum casing can loose strength. I would mike the casing each time you use it, and if the diameter gets larger each time, I'd be concerned.

Bob

 

[Donaldsrockets]

I have flown two G339Ns and I noticed that the anodizing where both ends of the liner meet is fading, it's like a pinkish white.

My guess is that hot propellants, like Warp-9 tend to fade the anodizing inside the casings.

Redline loads tend to do that as well.

Anyway, sounds awesome Dick, got a vid, I'd like to hear what this motor sounds like.

 

[rstaff3]

Thanks for the replies guys. I'm hoping someone will post photos/vids on the MDRA photo gallery.

 

[Johnly]

I burned 10 G69N-P reloads in three cases during the certification testing. The liner was pretty well spent by the end of the burn, but I didn't loose any coloration in the inside of the Aerotech hardware.

Did you grease the exterior of the liners during assembly. That generally helps reduce the baked on liner deposits from sticking to the hardware. The dyes used to color casings are heat sensitive. Discoloration inside the motor casing occurs with use, but if you see the exterior of the casing discolor, there is a good change that it has become heat damaged.

John

 

[rstaff3]

Thanks, sounds like I'm probably OK if you flew that many. I greased the liner as usual. The outside looks just fine, it's just the inside. I've never seen this in an AT (Dr. Rocket) case but all my Loki cases are discolored inside.

 

[cjl]

I've had some discoloration (but no physical damage) on blue thunder loads before. As long as it is only the coloring that is changing, and not the dimensions, you should be fine.

 

[DynaSoar]

Originally posted by jsdemar
Yes, this is the reason you don't normally see reloadable endburners. You should probably report this to Aerotech and TMT as a design flaw.

I've made several EX endburners over the years (from 12mm composite B's on up). The propellant needs to be fast and the case/liner combo needs to be thick. Aerotech's got one of the two right, it seems.

-John

I'm with John about reporting it to AT. I'd do so ASAP. They might have an explanation, or they might ask to inspect it. People not reporting problems is why there's more problems than there needs to be. If the present design has caused damage or undue wear, they'll likely replace it. If not, at least you'll know for sure. The alternative is flying it anyway without knowing whether it's safe still. That's not real responsible.

 

[rstaff3]

I don't know why you'd assume I wouldn't report it just because I posted a question here. I have emailed Gary and if he doesn't answer here will let you all know what he thinks for the record. I honestly was no so concerned about the one flight, but I'd like to burn a lot more of the motors. They are a bit expensive for a mere Hat of Death flight...but....

 

[rstaff3]

Gary replied that most of the liner will be consumed and the Warp-9 propellant will generate products that will discolor the dye. I'll keep an eye on the situation but won't be concerned for now.

Thanks for all the replies.

 

[DynaSoar]

Originally posted by rstaff3
I don't know why you'd assume I wouldn't report it just because I posted a question here.

I didn't assume you wouldn't. I did assume you hadn't decided, since you posted "This may be a question for AeroTech but since there are so many motor people here now...." 'May be' is a non-definitive statement. I encouraged you too because too few people do so, according to NAR S&T. They've received fewer and fewer MESS reports over the years.

And, had I intended only to encourage you to do so, I could have done that as well in private. I did so in public for its own sake as well as to be seen doing it by others, and so encourage them to do the same. Public discourse observed by others gets picked up and followed by others more than an outright public plea.

Even more, that goes for the comment about flying it without finding out not being real responsible. Sorry if you felt insulted, but I do believe that if there's a question as to safety, to ignore it would be.

I'm glad you contacted them, and that it's a non-issue.

 

[rstaff3]

Quite alright. You were kinda right as I was going to see if Gary responded here, but at the first suggestion I sent an email. And I agree that people should be encouraged to report failures. Right now I guess there is no failure, but will be prepared to report if there is.