Aerotech M750 nozzle issue

[Cameron Anderson]

First time M750 flyer here. There appears to be channel around the nozzle that the liner rests on (on the diagram screenshot you can see the liner does not rest in the groove but rather on it). My nozzle groove is gouged and chipped in several spots.

Anyone know the condemnation criteria for this nozzle component? Is it still good to fly or does it need to be replaced?

 

[crossfire]

Send the pictures to Carl at AT. I would want another nozzle.

 

[BSNW]

I agree.....I would NOT use that nozzle. Besides, for what you pay for that reload it should not look that way. Also consider safety issues if the nozzle breaks under pressure. On top of that....you dont want to risk damaging your rocket.
Andrew

 

[mikec]

Doesn't look unusable to me, but ask AT by all means.

 

[blackjack2564]

I would use it.[must see to be sure] O-ring goes below and one above in channel to seal.

Looks like surface mold chipping from here. [cosmetic ] The top edge above the chipping is still there by looks of it, all way around.
Besides I always glue everything together as a unit on M-motors and above anymore.

 

[Cameron Anderson]

Shot an email off to Aerotech, but with the holidays I'm sure it'll be a week or two before I hear anything, which is fine - this is probably an LDRS motor. And honestly, I'd fly it tomorrow if I had a launch planned. Damage is 1.25" on the circumference and the rest looks fine, but it's always good to get that expert opinion.

 

[Rocketjunkie]

No problem using it. Glue the nozzle into the liner when you glue the grains. This is a moon burner motor and you must glue the grain faces to make it into a single grain. Mine did not have an O-ring between the liner and nozzle. It will work even if you don't glue the liner to the nozzle.
Fun motor in 7.5", 32 lb. Goblin

 

[tbonerocketeer]

That's not the sealing surface, so it will be fine. If there is am oring inside the nozzle, it acts as a spacer for the propellant face. .

 

[Cameron Anderson]

You gotta love prompt customer service...Karl from Aerotech emailed me and offered to replace the nozzle. He said it should not have shipped due to the cosmetic issues but it was sound to fly.

 

[Andrew_ASC]

Yeah I’m no nozzle expert but I took a compressible gas dynamics class that dealt with supersonic flow design. Honestly if the damage was on the inside of throat or at nozzle exit diverging end. I would not want to fly it for fear of the exhaust gases eroding nozzle faster. But because it’s external damage it’s no issue. That is terrific that AT is sending a new nozzle anyways.

 

[Cameron Anderson]

Yeah I’m no nozzle expert but I took a compressible gas dynamics class that dealt with supersonic flow design. Honestly if the damage was on the inside of throat or at nozzle exit diverging end. I would not want to fly it for fear of the exhaust gases eroding nozzle faster. But because it’s external damage it’s no issue. That is terrific that AT is sending a new nozzle anyways.

External, non-load bearing surface...not an issue. I asked simply for the peace of mind since I had told myself it was fine before I sent the email, but it's always good to have that expert stamp on it.