CTI early ejection charge?

I recently flew my Madcow Torrent on a Cesaroni I175, configured for dual deployment with a StratologgerCF altimeter. Backup motor ejection charge was set for 11 seconds. At about 400 feet the rocket separated, did a bit of skywriting, and shortly after that the main chute deployed and it came down with the rear section badly zippered and the forward airframe banged up as well.

I'm trying to understand what went wrong. The attached photo shows that the motor was still firing when the rocket came apart, and it was at less than 500 feet, so I don't think it could've been drag separation. The data from the Stratologger shows that the drogue charge didn't fire until a few seconds later.

Could the motor ejection charge have somehow blown this early? That's what the photo seems to show, but I've never heard of that happening before.

Thanks in advance for any insights.

Video would be better if course but a quick glance at the photo seems to show smoke from the top of the booster section. Looks like either blow-by or the ejection charge. Did the motor look normal after the flight? The way the smoke is trailing and its color it looks like blow by. If not blow-by then the delay was likely trimmed incorrectly.


Tony

Did you hear/see the ejection charge pop on the descent? If you did, the failure is blow by. Happens ocassionally with CTI motors

What was the date code on the motor? CTI had a recall on the delay plug a couple of years ago, this could have been the cause.

Oct 2015 - right in the recall window. Stupid me.
Thanks for the responses.

Dang, I also forgot about the recall. Hopefully the damage wasn't too bad.

Tony

If you read the letter, there is no way to trace the forward closure to the date code. They say that certain shipments might be affected from a certain period. I remember it was really difficult to ID a bad forward closure but if you bought a motor from the listed dealers during the times they listed, you were given a replacement FWD closure
https://www.pro38.com/pdfs/Bulletin-Pro38_Forward_Clousre.pdf
I also remember the result was a Cato with severe damage to case & rocket as I experienced one of these. Was your case damaged?

That doesn't look like the forward closure blowout failures from the recall that I saw. In those, there was serious amounts of fire coming out both ends of the rocket. The entire delay grain area was also blown out, to the diameter of the delay grain. They also usually CATO'd about 25 feet off the ground.

boatgeek said:

That doesn't look like the forward closure blowout failures from the recall that I saw. In those, there was serious amounts of fire coming out both ends of the rocket. The entire delay grain area was also blown out, to the diameter of the delay grain. They also usually CATO'd about 25 feet off the ground.

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In actual practice it was total failure on down to small amounts of blow by. I had 2 that were just enough blow by to do this, confirmed by the recall.

Banzai88 said:

In actual practice it was total failure on down to small amounts of blow by. I had 2 that were just enough blow by to do this, confirmed by the recall.

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Good to know. The ones I saw were all the same and looked like someone had taken a torch (or rocket fuel) to the forward closure.

boatgeek said:

Good to know. The ones I saw were all the same and looked like someone had taken a torch (or rocket fuel) to the forward closure.

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All the ones I saw were that way too. The delay grain was forced up and out of the plastic forward closure.

No damage to the case, but a lot of scorching on the forward end. I didn't get a picture of it, but it cleaned up OK.

But now that I look at the CTI recall notice (linked by Tim above) I see that (a) my motor date stamp was just before the date range for affected motors and (b) it was not purchased from any of the listed dealers.
So blow-by? Other than the scorching on the end of the case, as I recall the motor looked normal after the flight.

I had a Pro24 6gr delay blow-by/early eject earlier this year (motor from 2010). Occasionally it happens, fortunately I just had a bit of zipper

jcantalupo said:

But now that I look at the CTI recall notice (linked by Tim above) I see that (a) my motor date stamp was just before the date range for affected motors and (b) it was not purchased from any of the listed dealers.
So blow-by? Other than the scorching on the end of the case, as I recall the motor looked normal after the flight.

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Probably doesn’t matter that you’re just before the date range or that it came from a different dealer. They might adjust to include your submission.
Was there a big hole clear through the plastic forward closure afterwards?