Exploding Rocket Motors. E9 motor malfunction (video)

mbecks

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I went to get the first launch of the winter season in with my rocket sled, now with its mounted camera, to see how the camera weight affected its travel. Unfortunately the rocket motor seemed to be faulty and exploded on launch. It sound more like a shotgun blast then a rocket motor. If you pause it at the moment of launch you can see that there is as much blast coming out the front as there is coming out the back.

Has anyone had something like this happen before?

[video=youtube;IaaC0kp5sD4]https://www.youtube.com/watch?v=IaaC0kp5sD4&feature[/video]
 

rharshberger

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I went to get the first launch of the winter season in with my rocket sled, now with its mounted camera, to see how the camera weight affected its travel. Unfortunately the rocket motor seemed to be faulty and exploded on launch. It sound more like a shotgun blast then a rocket motor. If you pause it at the moment of launch you can see that there is as much blast coming out the front as there is coming out the back.

Has anyone had something like this happen before?

[video=youtube;IaaC0kp5sD4]https://www.youtube.com/watch?v=IaaC0kp5sD4&feature[/video]

Anytime you use E9's you are playing roulette, I see at least one E9 Cato (or more) at every launch we hold.
 

markkoelsch

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The E9 is notorious. If everyone that had one fail would have filled out a mess report I would be willing to wager that they might have been decertified.
 

mbecks

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Well holy smokes I had no idea. It scared the crap out of me as you can see when It goes off I dropped the camera. I'm hoping to go big with the sled this winter. Possibly build a bigger one to scale up.
 

Cabernut

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Better when you get two to do that.

[youtube]s36T5yZSgfU[/youtube]
 

Buzzard

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At a DARS launch back in October I flew a scratch built model with a cluster of three E9-6 motors for a really nice flight. Later I attempted to fly a SEMROC Scorpion with an E9-8. That motor blew the nozzle at ignition and the model remained on the pad as the motor burned. It retained the ceramic end cap and the only damage was to the blast deflector. I did file a MESS report (I was the first MESS Chairman for Standards and Testing decades ago), but have not contacted Estes.
For those of you keeping score at home: E9-8 coded 08 14 01
 

Nytrunner

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I've heard thermal cycling is an issue with the E's.
If you fire them much colder than the highest temperature they've been exposed to, you're likely to have problems.
I'm basically not going to buy any until the spring/summer
 

ThirstyBarbarian

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I've got a bunch of E9 and E12 motors to work through. Personally, I've never had either kind cato, but I've seen lots of them explode at club launches, almost always on cold days. Our LCO delights in making a special announcement to watch for an exploding rocket every time one is launched! I don't currently have a working 24mm rocket, so I need to build one to work through the motor inventory. But now I don't really want to invest a lot of effort or money into a potential exploding rocket. Probably time for another Maxi Alpha 3...
 

Nytrunner

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But why did I only cato one out of a pack of three in the same launch?

Because you are not a good gambler. I believe that's the most scientific explanation that can be mustered at this point.
At least when it comes to E-bombs.

I've only flown one pack of E9's and they all worked. But then in October I saw a guy blow two in a row. Broke one of HARA's nice new ceramic blast deflectors (not to mention his Megamosquito and the other rocket)
 

cerving

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E9's and E12's cato with high regularity. I'm with markkoelsch, if MESS reports were submitted on all of them then chances are that they would be decertified, or at least retooled somehow to lessen the ignition spike. I won't fly either one of them... AT 24/40 RMS motors are a much better alternative.
 

aerostadt

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I went to get the first launch of the winter season in with my rocket sled, now with its mounted camera, to see how the camera weight affected its travel. Unfortunately the rocket motor seemed to be faulty and exploded on launch. It sound more like a shotgun blast then a rocket motor. If you pause it at the moment of launch you can see that there is as much blast coming out the front as there is coming out the back.

Has anyone had something like this happen before?

Mbecks, can you tell us the lot number for your E9 CATO?

The bad motor list that I have is as follows:

C11
A 11 08 10

E9
09-04-12
06-28-11
06-14-01 A
A 01 12 16
A 09 15 14
A 1-12-16

E12
A 08-18-11
A 11 15 11
 

TheTellurian

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Better when you get two to do that.

[youtube]s36T5yZSgfU[/youtube]

If I recall correctly that was an E12 in the booster to a E9 in the sustainer. The booster was unharmed though the sustainer had one section between the fins blown out yet was still flyable.


Richard :fly:
 

mbecks

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Mbecks, can you tell us the lot number for your E9 CATO?

The bad motor list that I have is as follows:

C11
A 11 08 10

E9
09-04-12
06-28-11
06-14-01 A
A 01 12 16
A 09 15 14
A 1-12-16

E12
A 08-18-11
A 11 15 11

if it's on the rocket motor casing I will pm you the numbers. I don't have the packaging that the set of 2 motors came in though.
 

mccordmw

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I've seen around 6 catos on LPR launches, and they've all been E9 or E12 motors. I won't touch them. 8 don't want to risk my hard work on a rocket to a faulty motor.
 

markkoelsch

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E9's and E12's cato with high regularity. I'm with markkoelsch, if MESS reports were submitted on all of them then chances are that they would be decertified, or at least retooled somehow to lessen the ignition spike. I won't fly either one of them... AT 24/40 RMS motors are a much better alternative.

Considering the regularity that they have Cato I think a likely decertification with a redesign and recertification makes sense. I had a three pack. 2/3 popped. Have not touched one since. Aerotech and the CTI 24mm motors rock.
 

mbecks

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The numbers off of the failed rocket motor are A 06 28 11 1. I think they are anyways. I say that because the 28 is printed upside down which means the 06 could be a 90 if it's also printed up side down.
 

Cabernut

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I think the fact that it was so cold was probably a big factor as well. I have launched E9s in mid-summer just fine. What was it again, 75? deg F difference from the highest temperature they have been exposed to will lead to a cato?

I had a C11-0 cato in April last year when it was about 45-50F I think, so if it was exposed to 120F in a hot trailer on a hot summer day prior to me purchasing it, then boom!
 

Bat-mite

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Both of my E9 catoes were in summer, and the motors were stored in my basement, which stays about 65*F year-round. If mine temperature-cycled, it was not while I had them. And then, again, I ask, why did two out of my three-pack light successfully, and one cato?
 

tab28682

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The numbers off of the failed rocket motor are A 06 28 11 1. I think they are anyways. I say that because the 28 is printed upside down which means the 06 could be a 90 if it's also printed up side down.

Looks like one of the known bad lots in the earlier post.
 

tab28682

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Both of my E9 catoes were in summer, and the motors were stored in my basement, which stays about 65*F year-round. If mine temperature-cycled, it was not while I had them. And then, again, I ask, why did two out of my three-pack light successfully, and one cato?

The packs could have temp cycled in transit to the dealer/retailer.

The most likely reason that two worked and one did not work would be that it was not assembled exactly like the other two. Perhaps tolerances piled up in the wrong direction.
 

Bat-mite

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The packs could have temp cycled in transit to the dealer/retailer.

The most likely reason that two worked and one did not work would be that it was not assembled exactly like the other two. Perhaps tolerances piled up in the wrong direction.

Agreed. So, is that a design flaw? It seems that if two of them did not have that problem, then they could have made the third one not have that problem? I realize that requires some re-engineering, and maybe it is not worth the money to them.

I remember the Packard-Bell computers from the 90s. They were selling so many PCs that if you got a bad one, they would just give you a new one. The slow-down they would have incurred by additional QA measures wasn't worth the loss of profit to them.

Of course, pretty soon Acer, Dell, HP and Compaq took over the market; so maybe it didn't work out for them after all.

Anyway, as long as no one else is producing 24mm E motors, Estes has no competition and controls the market.
 

ThirstyBarbarian

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Both of my E9 catoes were in summer, and the motors were stored in my basement, which stays about 65*F year-round. If mine temperature-cycled, it was not while I had them. And then, again, I ask, why did two out of my three-pack light successfully, and one cato?

I think the likelihood that all 3 would cato is lower than all 3 working properly. If a pack is mishandled or subjected to temperature cycling, it doesn't guarantee they will ALL blow. It increases the likelihood that each one will blow, and then you roll the dice for each one individually, not for the whole pack as a unit. It's not surprising to me that one of them worked ok.
 
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