What the...?

[PunkRocketScience]

I'm attaching on a pic of my PE 3" Gladiator. Anybody got an idea of what happened?

The CG was nearly a full diameter in front of the CG. If I hadn't happened to get this pic, I would have thought it just went unstable, but the recovery system clearly has deployed while under thrust, pulling the rocket for several loops until it smashed down into the ground. It was flying on a AT H165R-M, and there was no unusual scortching on the motor casing.

 

[BlueNinja]

Early ejection maybe? I'd otherwise say a blow-by except for the no scorch part... Then again, what did it do after it crashed? Maybe it was the acceleration pushing it out.

 

[solrules]

combustion gasses probably seeped around the delay grain.....did you put *light* coat of grease on the delay liner? What about the delay o-ring?

 

[PunkRocketScience]

Yup, I did grease the little bugger up. I may forget to add in the ejection charge now and then (most embarrassing), but I have yet to forget grease! Though combustion gasses are my current theory as well, as the rocket hadn't gone nearly far enough for a change in unvented external pressure to "suck" the NC off...

 

[Chuck Rudy]

This was a blown forward closure and it looks awfully similar. Perhaps the Oring didn't seal the top of the motor and when the motor came up to pressure so did the pressure in the payload area.

 

[solrules]

Originally posted by Chuck Rudy
This was a blown forward closure and it looks awfully similar. Perhaps the Oring didn't seal the top of the motor and when the motor came up to pressure so did the pressure in the payload area.

The only way for combustion gasses go *up* through the rocket (short of mushrooming the case and blowing the forward closure totally) is by going around the delay grain, lighting the ejection charge. Since Rocketman said the case was fine, the logical reason for the failure is a bad delay o-ring seal.

Rocketman: did you notice any cuts/scratches on the delay o-ring when you put it in? Do you still have the forward closure with the delay liner and everything?

Sorry for the rocket loss, but I have to admit it made a pretty cool picture....certianly a good story

 

[rdbones]

Todd:

I was talking to an RCS/Aerotech rep at Plaster Blaster and he informed me that they have been having a time with the Bule Thunder propellant seeping into the delay grain and causing them to burn faster than normal by a second or two (I had one cook off in 5 rather then 10 seconds).

Yours seems way too fast for that, but what was the delay on your motor ?

Always a possibility

 

[PunkRocketScience]

Hmmm... Thanks for the info Roy. It was a medium delay - so I would have expected something around 7-10 seconds instead of just leaving the pad

 

[PunkRocketScience]

Unfortunately I'm compulsivly neat with my casings, so it was clean as soon aas it was cool. I didn't notice anything odd about the rings or liner though. Possibly I over greased the liner? It seemed to come out easier than usual...