Aerotech SU motor failure?

[gciarlo]

Greetings,

New to rocketry and recently launched an Aerotech Mustang on an Aerotech single use F32-8T with a copperhead ignitor. First launch was great. Straight up, chute deployed near apogee (as near as I could tell), easy recovery. Second launch, same set up, resulted in CATO. The video I took shows the chute deploying before the rocket even clears the rod. Rocket went about 7 feet in the air then hit the deck in a firey, smokey mess, scaring the crap out of my 4 year old before coming to rest. The motors forward closure is gone (see pic), the rockets ejection gas baffle and eye hook are gone, and the inside of the rocket is toast. The motor with the 29/24 adapter (also toast, see pic) was ejected at some point. Retention was the stock hook that comes with the kit. The hook is still solidly attached to the rocket. Is it possible I inserted the ignitor too far in and ignited the ejection charge at the same time as the propellant? Is that even physically possible? Do these types of motors fail very often and if so, how do they typically fail? Any insight would be appreciated. Like I mentioned, I'm fairly new to this and trying to determine if I did something wrong or if it was just a case of bad luck . Sorry for the poor quality of the pictures. Thanks!

 

[cbrarick]

Looks like forward closure failure. This happens on rare occasion. How old was the motor? Was it dropped (the plastic can be brittle if hit "just right" Go to aerotech's website for information on how to get a warentee replacement....they're pretty good on that for newbie's. You can't insert the copper head too far, you want to get it all the way to the top (if you have it on the very aft end, the motor will burn much like a road flare for some time before finally coming up to pressure)

good luck!

Greetings,

New to rocketry and recently launched an Aerotech Mustang on an Aerotech single use F32-8T with a copperhead ignitor. First launch was great. Straight up, chute deployed near apogee (as near as I could tell), easy recovery. Second launch, same set up, resulted in CATO. The video I took shows the chute deploying before the rocket even clears the rod. Rocket went about 7 feet in the air then hit the deck in a firey, smokey mess, scaring the crap out of my 4 year old before coming to rest. The motors forward closure is gone (see pic), the rockets ejection gas baffle and eye hook are gone, and the inside of the rocket is toast. The motor with the 29/24 adapter (also toast, see pic) was ejected at some point. Retention was the stock hook that comes with the kit. The hook is still solidly attached to the rocket. Is it possible I inserted the ignitor too far in and ignited the ejection charge at the same time as the propellant? Is that even physically possible? Do these types of motors fail very often and if so, how do they typically fail? Any insight would be appreciated. Like I mentioned, I'm fairly new to this and trying to determine if I did something wrong or if it was just a case of bad luck . Sorry for the poor quality of the pictures. Thanks!

 

[MaxQ]

Greetings,

New to rocketry and recently launched an Aerotech Mustang on an Aerotech single use F32-8T with a copperhead ignitor. First launch was great. Straight up, chute deployed near apogee (as near as I could tell), easy recovery. Second launch, same set up, resulted in CATO. The video I took shows the chute deploying before the rocket even clears the rod. Rocket went about 7 feet in the air then hit the deck in a firey, smokey mess, scaring the crap out of my 4 year old before coming to rest. The motors forward closure is gone (see pic), the rockets ejection gas baffle and eye hook are gone, and the inside of the rocket is toast. The motor with the 29/24 adapter (also toast, see pic) was ejected at some point. Retention was the stock hook that comes with the kit. The hook is still solidly attached to the rocket. Is it possible I inserted the ignitor too far in and ignited the ejection charge at the same time as the propellant? Is that even physically possible? Do these types of motors fail very often and if so, how do they typically fail? Any insight would be appreciated. Like I mentioned, I'm fairly new to this and trying to determine if I did something wrong or if it was just a case of bad luck . Sorry for the poor quality of the pictures. Thanks!

Bad Luck...most likely.
Sh*t happens.
I know that won't ease the pain but maybe this story will encourage you....

Years ago I had a great first flight on my Cosmodrome Aerobee - Hi two stager. Had an Aerotech G80-4 single use motor in the booster and Aerotech reloadable sustainer - both did very well.
I was feeling real good about my composite two stage experience....................so far.

The next flight ...the booster exploded on the pad...I mean into smithereens.

The motorcase was in shards...the propellent grain was mostly intact, laying in the debris field of my booster.... - snuffed out by the sudden loss pressure.
Apparently there was a bad batch of plastic motor casings that failed a pressure test.

I rebuilt a new booster using the recovered parts .....brought it back next season....

SAME THING HAPPENED.

Exploded immediately on the launch pad.

I must say Aerotech was very responsive in getting me replacement motors...

After all that ....I ONLY fly it now with "reloadable" G-80s in the booster....(with a change out to a short delay -since the booster really needs the short delay).

Hold on to those engine pieces and send them a failure notice.

 

[gciarlo]

Thanks for the info! I purchased the motors about 2 months ago. Not dropped. At least not by me. I will definitely talk to Aerotech.

Regards,

 

[cwbullet]

It looks like a forward failure. I talk to AT and they made it right a few years ago. Also make sure you report it to NAR:

https://www.nar.org/NARmessform.html.

 

[gciarlo]

Thanks for the story! I must say, I was a little discouraged, as it was my 1st attempt with the mid level composite motors. Encouraging to know it probably wasn't me. At least this time!

Regards

 

[gciarlo]

Thanks! I'll do that.

Regards,

 

[cwbullet]

I have has 2 Catos with single use. Both motors were replaced. I am sure there will be more. Do not let it discourage you. Even the most experienced flyer has failures.

 

[dave carver]

It's the nature of the sport. I've been lucky, flown my share of single-use motors without a failure. On the reloadable side I've had all kinds of problems. From a crumbly fuel in an H97 that crumbled and clogged the nozzle blowing the motor out. Another clogged nozzle caused a I195 to overpressurize and blow, splitting the case. Flew one of the first I435, nozzle cracked, vectored thrust made it loop like a cowboy's lariet before going stable, horizontal, and smashing into the lakebed next to a group of RC fliers. Last was a "M" class Kosdon motor that spit the nozzle out shattering it into dust and bending a reinforced 1/4 inch steel blastplate.

So many things to go wrong but I still keep flying them

 

[rocketgut1967]

I have never had oen fail like that, btu I have had a G fast jack fail by over pressurization and push out the forward closure on a single use.

 

[accooper]

I have seen a failure like that just last month. One of the guys I fly with had one fail. We figured, maybe wrongly, that as the propellant ignited, the igniter slid down the slot.

Only God knows.

Andrew

 

[n3tjm]

What do you mean by reloadable G80's ?

 

[accooper]

it was a G Aero-Tech reload, close to an 80. That's what I meant.

Sorry

Andrew

 

[JohnCoker]

It looks like a forward failure. I talk to AT and they made it right a few years ago. Also make sure you report it to NAR:

Here is the correct URL:
https://motorcato.org/

Please report all motor failures. (Soon you will be able to see statistics so this helps us all.)

 

[cwbullet]

I think I have reported all of them.