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Lowpuller

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Check out video and tell me what you think happened here.....

This is an AT RMS E-18 White Lightening, 24mm motor.

I have assembled many of these motors and the E-18 is my favorite, however I do have an E-18 question I will put up in another post.

https://youtu.be/63jHCD23L-g

I was able to recover all of the pieces. The forward closure was stuck in the 24-29 adaptor.

The case was bent on the forward end I am assuming from being spit into the rail base. The rear end of the case is damaged apparently from the motor hook. The motor was seated under the hook, and tape in place on top of that (club rule).

The grain and liner were laying on the ground separate from the case. Pics of what I recovered attached.

Bottom line, rocket damaged, adaptor damaged, casing destroyed, reload spent.

ImageUploadedByRocketry Forum1503861460.224930.jpg

ImageUploadedByRocketry Forum1503861482.161248.jpg

ImageUploadedByRocketry Forum1503861499.704027.jpg

ImageUploadedByRocketry Forum1503861526.001278.jpg

ImageUploadedByRocketry Forum1503861541.608758.jpg

ImageUploadedByRocketry Forum1503861554.960006.jpg

ImageUploadedByRocketry Forum1503861584.341605.jpg

More pics or follow
 

crossfire

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Yes make sure you file a MESS report. Its the only motor makers will know if any problems are going on.
 

djs

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I've had stuff like this happen when the ignitor plugged the nozzle, overpressurized the case, and all the magic smoke came out. Your thoughts on this?

Second question- in one of the pictures, it shows the delay grain at the bottom of the forward closure. Did this reload have a delay grain spacer or not?

FYI- I swore off the 24/40 reloads after blowing cases too often. For some reason, I can't get them to work right, even though I can put together a 29/40-120 reload just fine.

At least (from what I can tell) the rocket damage isn't too bad. Hopefully it flies again soon!
 

markkoelsch

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First, sorry to hear and see the pictures.

Secondly, as others have said please fill out a mess report at motorcato.org

So, a few questions.

1) this was using an AT First Fire Junior, or was it a different ignitor?

2) was there a pressure relief hole cut in the red cap?

3) neither the delay grain or main propellant grain continued to burn, correct?
 

rockets

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I wonder if the motor over-pressurized, because that casing looks like it took some big hit.
Thanks,
 

scsager

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Here is my theory -
Motor starts to burn, pressure starts to build up inside the case.
Igniter gets jammed in nozzle, does not get expelled from case.
Case now plugged by igniter, over pressurizes, forward closure comes off.
Fwd closure stopped by adapter, expanding gasses push motor past hook -
- Bang -
 

rockets

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Here is my theory -
Motor starts to burn, pressure starts to build up inside the case.
Igniter gets jammed in nozzle, does not get expelled from case.
Case now plugged by igniter, over pressurizes, forward closure comes off.
Fwd closure stopped by adapter, expanding gasses push motor past hook -
- Bang -
Sounds about right.
Thanks,
 

Steve Shannon

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People say this like a warranty claim doesn't tell them anything.
You're right, warranty claims certainly tell the manufacturers a great deal, but the don't get communicated to the certifying agencies (CAR, NAR, and TRA).
MESS reports inform the certifying agencies. The certifying agencies then must use the information to communicate concerns to the manufacturers.
Both contribute to greater reliability, which benefits the end user.
Even motor problems that would not be submitted for warranty service should have MESS reports. That helps identify other problems such as confusing instructions.
 
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dpower

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So it sounds like the forward closure separated from the case. Is the casing split, or did the threads give way? What do the threads look like on both pieces? Even though the casing is distorted, if the threads failed, that should be visible on one of the two pieces.

Over pressure is a possible explanation, the First Fire Jr is fairly large for 24mm RMS, depending how much pyrogen was on the tip. Did it insert easily through the nozzle, or did you build the motor around it? They used to ship with copperheads, and now ship with First Fire Mini.

The small number of threads on this case is certainly it's weak point, I've talked to some flyers that have had those threads fail, though I haven't experienced one.
 

crossfire

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So it sounds like the forward closure separated from the case. Is the casing split, or did the threads give way? What do the threads look like on both pieces? Even though the casing is distorted, if the threads failed, that should be visible on one of the two pieces.

Over pressure is a possible explanation, the First Fire Jr is fairly large for 24mm RMS, depending how much pyrogen was on the tip. Did it insert easily through the nozzle, or did you build the motor around it? They used to ship with copperheads, and now ship with First Fire Mini.

The small number of threads on this case is certainly it's weak point, I've talked to some flyers that have had those threads fail, though I haven't experienced one.
I have flew a fair amount of AT DMS line of motors and seems no matter what the size of motor from I-K the First Fire igniter is the same size. Just doesn't seem right to me.
 

Lowpuller

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Thanks for the advice and questions.

MESS report has been filed however in this case I doubt I still have the serial number from the packaging.

Answers to questions follow:


The delay grain did not have a spacer.

The igniter was an AT First Fire Wire Junior, it had been fully spit from the nozzle.

The red cap over the nozzle had a relief hole cut in the typical "45 degree" fashion.

Neither the delay nor propellant continued to burn.

No threads were damaged that I can find. The forward closure looks fine, the case was bent most likely by striking the rail stand, but the threads appear to be good. Regretfully I was using 3 new cases that day and one used case, that I have used many times, but I can't tell weather my old case or one of the new cases failed. One of the new cases, was never fired but was made a few years back.

Warranty claim has been filed with AT including video and pics.
 
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3stoogesrocketry

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Your problem appears to be it the first two pictures. The grain looks like it was burning down the seem of the casting tube ( evidence by the charing in the spiral and what appears to be the separation of the casting tube to the grain interface . How easy will the casting tube peel of the grain , and is there any signs of the grain burning on the out side of the grain ?

Eric
 

Steve Shannon

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Your problem appears to be it the first two pictures. The grain looks like it was burning down the seem of the casting tube ( evidence by the charing in the spiral and what appears to be the separation of the casting tube to the grain interface . How easy will the casting tube peel of the grain , and is there any signs of the grain burning on the out side of the grain ?

Eric
Every small motor with a spit closure that I've seen has exhibited the charring along the spiral. I suspect that's just gas flow at startup or while the grain is being ejected. Of course maybe that's been the cause of those I've seen [emoji15]
 
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H_Rocket

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No threads were damaged that I can find. The forward closure looks fine, the case was bent most likely by striking the rail stand, but the threads appear to be good.
Whatever comes of this, do not use that case or closure again. If enough force was applied to spit the closure the threads on both parts are probably damaged. If you were to measure the case ends, I expect you would find one measurably larger than the other and on very close examination of the closure you would see distortion on the threads. Those two pieces cannot be expected to seal properly again, either together or in combination with other parts.
 

Lowpuller

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Eric,

The casing appears to be attached to the grain, I didn't try to hard to peel it off as I want tot hear from AT first. I see no evidence of burning between the grain and liner.

I always grease the casing exterior with Super Lube.

H_Rocket, believe me, I don't plan to use and of those parts again, I spend to much time on my rockets, it ain't worth the risk! (We count "ain't" as proper English in NC).
 
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timb

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Check out video and tell me what you think happened here.....

This is an AT RMS E-18 White Lightening, 24mm motor.

I have assembled many of these motors and the E-18 is my favorite, however I do have an E-18 question I will put up in another post.

https://youtu.be/63jHCD23L-g

I was able to recover all of the pieces. The forward closure was stuck in the 24-29 adaptor.

The case was bent on the forward end I am assuming from being spit into the rail base. The rear end of the case is damaged apparently from the motor hook. The motor was seated under the hook, and tape in place on top of that (club rule).

The grain and liner were laying on the ground separate from the case. Pics of what I recovered attached.

Bottom line, rocket damaged, adaptor damaged, casing destroyed, reload spent
Man I feel your pain; the good news is that these rarely fail - that's my experience anyway (hope I didn't just jinx myself). The E18 is one of my favs, too. It appears to have let go right at ignition.
 

Lowpuller

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Ok check out these detail pics!!!

Ignition, in Slo mo I can see the igniter move away
ImageUploadedByRocketry Forum1503895822.967140.jpg

Flame
ImageUploadedByRocketry Forum1503895961.305019.jpg



Casing being ejected, look at the flame
ImageUploadedByRocketry Forum1503896057.803394.jpg

Casing striking the blast deflector
ImageUploadedByRocketry Forum1503896099.811222.jpg

Blurry close up of casing striking blast deflector
ImageUploadedByRocketry Forum1503896180.699560.jpg
 

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