Super hot A8-3 ejection charges

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rbeckey

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Today we had a Rocket Day at the park. Everything went very well except for three pesky A8-3s that seemed to be under powered on the thrust end and over powered on the ejection. The motors came from a Blast Off Pack purchased this spring. All three stripped chutes. One melted the internal motor mount parts of a Chrome Dome, and another caused a serious "Estes Dent" in a scratch K27 Honest John. :eek: I will file a mess report and contact Estes next week. B and C motors from the same box were flawless.
 

jflis

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At the CMASS launch today we saw that with the A8-3 and B6-4 (and even an A3-4T). One was so hot that it blew itself (the casing) out of the rocket but still had enough oomph to rip the nose cone from the screw eye!
 

r1dermon

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yeah, estes should consider switching their ejection charges from TNT to BP. it would make a huge difference. chuckle chuckle chuckle....yeah, i had an E9-6 on today that ripped two shroud lines out of the chute at eject. and this shock cord is like...6 feet long, so it had to be a REALLY hot ejection charge. however, the motor had full power.
 

Chuck Rudy

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Maybe it was installed upside down. ;-)










Before you start , just havin' fun. :)
 

rbeckey

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Heck, the A8-3s I had probably would have had more thrust installed upside down!
 

DynaSoar

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Originally posted by rbeckey
Today we had a Rocket Day at the park. Everything went very well except for three pesky A8-3s that seemed to be under powered on the thrust end and over powered on the ejection. The motors came from a Blast Off Pack purchased this spring. All three stripped chutes. One melted the internal motor mount parts of a Chrome Dome, and another caused a serious "Estes Dent" in a scratch K27 Honest John. :eek: I will file a mess report and contact Estes next week. B and C motors from the same box were flawless.
Can we get some dat/batch numbers on these so we can check ours and watch for problems?
 

Purkeypilot

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I know this is a decade old thread, but I searched this issue before I posted the question...

The last 4 Estes A8-3 motors that I have flown have either singed the hell out of the rubber band shock cord or badly burned/melted the parachute. During the same flight sessions, I have flown the same rockets on multiple B6-4 and C6-5 motors with zero issues. The A8-3 ejections charges seem really over-the-top harsh. Have anyone else made this observation lately?
 

d11rok

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I've been flying my low power fleet with mostly A8-3's. and havent had a problem with any. parachutes and shock cords have all remained intact
 

DizWolf

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Just flew about 40 A8-3's with scouts. No toasty's
 

Purkeypilot

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Dang! Really!? I packed the same rockets the same way with B6-4 and C6-5 motors and had no problems. All 4 of the spicy 8-3s were from the same Bulk (24) box of A8-3s...I wonder if it's the lot??
 

bobkrech

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I know this is a decade old thread, but I searched this issue before I posted the question...

The last 4 Estes A8-3 motors that I have flown have either singed the hell out of the rubber band shock cord or badly burned/melted the parachute. During the same flight sessions, I have flown the same rockets on multiple B6-4 and C6-5 motors with zero issues. The A8-3 ejections charges seem really over-the-top harsh. Have anyone else made this observation lately?
If you still have the motor casings, what are the date codes?

Bob
 

Purkeypilot

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If you still have the motor casings, what are the date codes?

Bob
A091514 in an oval above the "Warning - Flammable. Is that the date code? I just went out of town today and am looking at a picture I have of two of them. Won't be back home for a couple weeks to check first hand.
 

DizWolf

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Mine spanned a pretty long time.... some from 15 years old, some a few years old, and a 24 pack and 3 pack recently purchased. I'd pull codes but I think they all got tossed.

Not to say i've never seen a random estes fireball...

D12-3 15 years old

 
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bobkrech

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A091514 in an oval above the "Warning - Flammable. Is that the date code? I just went out of town today and am looking at a picture I have of two of them. Won't be back home for a couple weeks to check first hand.
That appears to be the date code and that's the first report of this issue for it.

Please report this to both motorcato.org and to Estes Customer Service.

Motorcato.org is a website administered NAR for NAR, TRA and CAR to gathering statistics on motor failures. The statistics are review annually as less than 200 failures are reported in a year and there are more than 1000 motor types. You need at least several failures in 1 motor lot to begin to raise a level of concern.

The motor manufacturer is responsible for the day to day QC of their motors and if you don't let them know about a motor problem, they will assume quite reasonably that all is well. Estes can make ~5000 motors per day per Mabel engine manufacturing machine and they static test 2-3% of the production (that's 100-150 motors per day per machine and their successful test firing rate is >99+%) so in the factory QC testing, motor failures are rare.

All motors "cure" for several weeks after manufacture and experience various mechanical and thermal stresses during shipment and storage so it is not surprising that the observed field failure rate appears to be higher. Based on personal observations the real on average motor failure rate is between 1% and 2% which I consider "normal".

Bob Krech, Tech Officer, NAR S&T

BTW - I remember the over-energetic ejection charges in the 2004 period. I keep breaking my Edmonds glider in half when the ejection charge blew.

Bob
 
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