What to do with CATO-prone motors

Just got a pack of E12-8 motors via mail order with the infamous 08-18-11 date code. Don't have any rockets I'd like to blow up. Options?

Saucers? Ground tests? Cheapy test rockets for winds at altitude?

blackbrandt said:

Saucers? Ground tests? Cheapy test rockets for winds at altitude?

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Ground test them, and film them at a high fps rate...


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Give them to someone who you have no love for and who is unaware of the history of those motors. "Hey, Dude, sorry about your CATO and it was a nice rocket, too." Snicker, snicker...

Ya mean like this?

[video=youtube;pgqXTvh7TsQ]https://www.youtube.com/watch?v=pgqXTvh7TsQ[/video]

I wonder if you could call Estes customer service and just tell them you don't trust the motors. I wonder what they would do.

If you don't have any rockets you are willing to risk them in, then you could build something you are willing to lose. Maybe something trash-built out of paper towel rolls and soda bottles? (Would it be wrong to just tape them to a stick and send them up bottle rocket stye?)

ThirstyBarbarian said:

(Would it be wrong to just tape them to a stick and send them up bottle rocket style?)

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Yes it would.. you need to glue them to the stick. :grin:

Bottle rocket style would be more a firework than anything at that point. Whatever laws apply there.

I have some F30s I got in a bad batch bought 5 - 2 failed - all same lot. AT send me F32s as replacements - Didn't trust F30s. Still have the bad F30s as I can't ship them back. Might be able to dump out the ejection, fill the forward closure that fails with epoxy, and use them in a saucer. Haven't done that yet.

I would try the Estes route first. Giving them away would be a big mistake, friend or foe, someone could get injured

...ummm...yeah...I did that after I blew up a just built FSI Black Brant ll on a FSI F100 Explodi-jet I only had 1 successful flight of a F100 and that was out of 3 and it happened to be the "bottle rocket" I made from the last one. I made it up special for a 4th of July. After the rest of the neighborhood had burned off somewhere around $1000 of fireworks it was the "Grand Finale". I inserted the stick into an old bumperjack and told the crowd to stand back, it could blow upon ignition, go up 10 feet and blow, or go about 3000 feet. To my suprize it actually went up It was a F100-8. After a bit people were saying it was a dud, I just smiled and counted, "5 one thousand...6 one thousand...7 one thousand, 8 one thousand!!!" I had built up the fore end to hold more...stuff. I had a broken Roman Candle so I put the little balls into it as well as the powder. It looked magnificent when it went off waaaaay up there. Might be the only launch I ever had where people cheered

Oh, yeah, I wanted to add this was 20 years ago, Statute of Limitations on the Misdemeanor was up a long time ago

Winston said:

Just got a pack of E12-8 motors via mail order with the infamous 08-18-11 date code. Don't have any rockets I'd like to blow up. Options?

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Well.. since there seems to be more catos from this date code rather than being "prone" to cato simply from being in this batch, I wouldn't worry too much.

You could build and fly a naked rocket for fun... give the motors to someone who isn't as fearful... or soak them in water to destroy them..

Personally I would just wait a few months until the height of summer. Seems the BP motor catos are more "prone" in the colder temps.


Jerome

The temperature at firing is not the problem with the 2 noted date codes of E9 motors or the one noted date code of E12 motors. Something else other than temperature cycling is the root problem with these.

I fired a bunch of E12-8 motors from that date code and never had one fail, but YMMV. I fired my last 3 E12-0 motors from the date code last month and they all worked fine.

The E9 motors from the 2 known problem date codes had a few catos.


I filled in MESS forms and notified Estes. Since I had burned up 20 E9 and 3 E12 motors from the noted date codes I documented the launches and provided the infor to Estes.


They replaced the damaged or destroyed models with kits that are currently available and replaced the motors with a pretty decent number of D12 packs since they can USPS surface mail the D12 motors and the E motors would have required expensive HAZMAT shipping.

I now have nothing but E9 and E12 motors from earlier and later date codes with no reported problems. And I have a bunch of the 29mm E16 and F15 motors and there have been zero problems with those.

JeromeK99 said:

Well.. since there seems to be more catos from this date code rather than being "prone" to cato simply from being in this batch, I wouldn't worry too much.

You could build and fly a naked rocket for fun... give the motors to someone who isn't as fearful... or soak them in water to destroy them..

Personally I would just wait a few months until the height of summer. Seems the BP motor catos are more "prone" in the colder temps.


Jerome

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rocketgeek101 said:

Ground test them, and film them at a high fps rate...

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Even though the mail order source emailed that they'll take them back and provide a refund, I'm going to test fire them. I just happen to have a 24mm motor test stand (actually just a motor "holder") I made from scrap wood that anchors to the ground with tent stakes which I recently used just for the purpose of testing an AT F24 RMS motor that had been loaded for ten months. Motor burned fine, o-rings looked like-new after firing.

I'll use that same rig to test all three the E12-8s and HD video record them. I don't own a video camera than can do high fps.

Testing them will take them out of circulation and provide a few more failure rate data points. Now, watch, all three will work just fine. I'll let everyone know what happens.

Nice video Matt, thanks.

Winston said:

Even though the mail order source emailed that they'll take them back and provide a refund, I'm going to test fire them. I just happen to have a 24mm motor test stand (actually just a motor "holder") I made from scrap wood that anchors to the ground with tent stakes which I recently used just for the purpose of testing an AT F24 RMS motor that had been loaded for ten months. Motor burned fine, o-rings looked like-new after firing.

I'll use that same rig to test all three the E12-8s and HD video record them. I don't own a video camera than can do high fps.

Testing them will take them out of circulation and provide a few more failure rate data points. Now, watch, all three will work just fine. I'll let everyone know what happens.

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All the shipping fun probably means they can only take them back in person. I contacted AT directly instead of the vendor because of this for my issue.

I'd build a couple boilerplate rockets out of scrap parts to fly 'em in, and if they go blooey, fill out a MESS form, send 'em in to Estes and they'll probably send you a couple of replacement kits.

Burning them off in a 'test stand' (unless it's a real test stand from which you can get some actual information) is just like throwing the money out the window.

Long long ago in my teen years we lit off some motors in 'static firings' simply by burying them nose down in the dirt. Similarly a waste of money.

JStarStar said:

I'd build a couple boilerplate rockets out of scrap parts to fly 'em in, and if they go blooey, fill out a MESS form, send 'em in to Estes and they'll probably send you a couple of replacement kits.

Burning them off in a 'test stand' (unless it's a real test stand from which you can get some actual information) is just like throwing the money out the window.

Long long ago in my teen years we lit off some motors in 'static firings' simply by burying them nose down in the dirt. Similarly a waste of money.

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I also plan to measure the precise OD of each motor at various stations along their length and macro-photograph the nozzles and end plugs. Since I have two maker group meetings in the near future, I'm going to ask if anyone knows of anyone who can provide free X-Ray and/or ultrasound analysis of the motors for the mention of their firm's name, looking for ramming density variations, nozzle or fuel grain wall separation, grain cracks, etc.

Recycle bin saucers and spools. Everyone has an old spool laying around somewhere, no? Why waste a good explosion sticking them in the ground?

Cluster all three, and name the rocket Deer Hunter.

ThirstyBarbarian said:

Cluster all three, and name the rocket Deer Hunter.

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Cluster is a fantastic idea.

shreadvector said:

And I have a bunch of the 29mm E16 and F15 motors and there have been zero problems with those.

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I haven't had any problem with F15's, flew 8 of them last weekend. I'm waiting to see what a few years in the distribution chain does to them.

dave carver said:

...ummm...yeah...I did that after I blew up a just built FSI Black Brant ll on a FSI F100 Explodi-jet I only had 1 successful flight of a F100 and that was out of 3 and it happened to be the "bottle rocket" I made from the last one. I made it up special for a 4th of July. After the rest of the neighborhood had burned off somewhere around $1000 of fireworks it was the "Grand Finale". I inserted the stick into an old bumperjack and told the crowd to stand back, it could blow upon ignition, go up 10 feet and blow, or go about 3000 feet. To my suprize it actually went up It was a F100-8. After a bit people were saying it was a dud, I just smiled and counted, "5 one thousand...6 one thousand...7 one thousand, 8 one thousand!!!" I had built up the fore end to hold more...stuff. I had a broken Roman Candle so I put the little balls into it as well as the powder. It looked magnificent when it went off waaaaay up there. Might be the only launch I ever had where people cheered

Oh, yeah, I wanted to add this was 20 years ago, Statute of Limitations on the Misdemeanor was up a long time ago

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OMG! I had a buddy of mine convince me the F-100's were the harbingers of Death, so for a short little pyro show in the desert-I made headings for about of dozen of these bottle rockets. Bamboo garden sticks-but they were electrically fired. I was so pissed every one actually flew fine! Best one was a whistle and strobe combo. yeah-everybody clapped and cheered, but they woulda been better in a rocket! Wish I still had 'em.

fyrwrxz said:

OMG! I had a buddy of mine convince me the F-100's were the harbingers of Death, so for a short little pyro show in the desert-I made headings for about of dozen of these bottle rockets. Bamboo garden sticks-but they were electrically fired. I was so pissed every one actually flew fine! Best one was a whistle and strobe combo. yeah-everybody clapped and cheered, but they woulda been better in a rocket! Wish I still had 'em.

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Yep, dang things were that reliable, never did what you wanted them to

Took a good look at the 08-18-11 motors today, nozzles normal, other end not so much:



None of my other D12s, E9s, or E12s have that issue. The thinning of the rightmost casing in its upper left quadrant is not a perspective illusion and the middle one is also thinner in same quadrant, but it's less obvious in the photo. Looks like either casing misalignment during ramming, out-of-spec (off-center bore) casings, or an offset ram (toward the upper left) which caused the off-center casing bore or ? Off-center ramming would cause undercompaction of one side of the grain and a higher burning rate in that quadrant.

Edit: The lower right quadrant of the clay end plug that was undercompacted was the part that fell away during handling prior to packaging.

I would just build a junk rocket, fly the motors and report any catoes and be done with it.

My preferred junk rocket design is somewhat short and stubby; something that allows a burped chunk of propellant to exit the rocket quickly without doing much damage. Estes Fat Boy or Big Daddy. I also use my old SPEV as a junk motor rocket for suspect B and C motors (it's a normal proportioned rocket, but has a short, wide parachute compartment).

RoyAtl said:

I would just build a junk rocket, fly the motors and report any catoes and be done with it.

My preferred junk rocket design is somewhat short and stubby; something that allows a burped chunk of propellant to exit the rocket quickly without doing much damage. Estes Fat Boy or Big Daddy. I also use my old SPEV as a junk motor rocket for suspect B and C motors (it's a normal proportioned rocket, but has a short, wide parachute compartment).

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Nah, I like the investigatory process. I've never read an explanation of why this batch has such a high failure rate and I'd like to see if off-center ramming was the likely cause. I'll be talking to folks from Team Estes at a NAR regional launch this weekend and I'll see if they want these back for analysis or if I should just go ahead and static test them in their presence. Maybe I'll be able to get Estes to exchange them for $20 worth of Estes rocket kit or replacement motors, but if I can't, the $20 I paid for them will be worth it to quell my failure-mode curiosity if I safely ground test these.

Winston said:

Nah, I like the investigatory process. I've never read an explanation of why this batch has such a high failure rate and I'd like to see if off-center ramming was the likely cause. I'll be talking to folks from Team Estes at a NAR regional launch this weekend and I'll see if they want these back for analysis or if I should just go ahead and static test them in their presence. Maybe I'll be able to get Estes to exchange them for $20 worth of Estes rocket kit or replacement motors, but if I can't, the $20 I paid for them will be worth it to quell my failure-mode curiosity if I safely ground test these.

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I dunno, thirty years ago I traded Mary Roberts an box of old suspect engines for them to test and got back new ones. I don't think she wanted to make the trade, but she did. But she never told me the results of the testing. So I suspect they just junked them. Then again, I did get new motors, so maybe you should go ahead and try, especially if you can talk to them (and transfer the motors) face to face.

This is not correct. Casings are wound like a roll of toilet paper. it is impossible for one side to be thinner than the other, but it is possible to see one side appear to be thicker because it 'relaxed' and appears thicker. There can also be part of the end 'smooshed' a bit inward and that can make that side look thinner. you can tell that you are looking at a 'smooshing' effect by observing the spiral lines of the paper layers. you will see that the thin side layers have been smooshed down and inward. This is only an effect on the end of the casing and has nothig to do with the nozzle end or the propellant right above the nozzle. The problem area is in the propellant right above the nozzle area and you cannot see which ones are bad visually.

Winston said:

Took a good look at the 08-18-11 motors today, nozzles normal, other end not so much:

None of my other D12s, E9s, or E12s have that issue. The thinning of the rightmost casing in its upper left quadrant is not a perspective illusion and the middle one is also thinner in same quadrant, but it's less obvious in the photo. Looks like either casing misalignment during ramming, out-of-spec (off-center bore) casings, or an offset ram (toward the upper left) which caused the off-center casing bore or ? Off-center ramming would cause undercompaction of one side of the grain and a higher burning rate in that quadrant.

Edit: The lower right quadrant of the clay end plug that was undercompacted was the part that fell away during handling prior to packaging.

Click to expand...

shreadvector said:

This is not correct. Casings are wound like a roll of toilet paper. it is impossible for one side to be thinner than the other, but it is possible to see one side appear to be thicker because it 'relaxed' and appears thicker. There can also be part of the end 'smooshed' a bit inward and that can make that side look thinner. you can tell that you are looking at a 'smooshing' effect by observing the spiral lines of the paper layers. you will see that the thin side layers have been smooshed down and inward. This is only an effect on the end of the casing and has nothig to do with the nozzle end or the propellant right above the nozzle. The problem area is in the propellant right above the nozzle area and you cannot see which ones are bad visually.

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Yes, I'm familiar with how parallel wound paper casings are made and a deformed new casing is unlikely. As I said, the deformation of the casing can also be from an off-center ram position in relation to a perfect motor case. Somehow, the rams and casings got out of alignment. I think that's the most likely cause of what we see. I'm going to do an out-of-round measurement since the two worst looking casings appear slightly oval at the forward end, something that doesn't show up in the photo. I'll see if I'm imagining that due to an illusion caused by the partial clay plug and if the oval deformation does in fact exist, I'll see how far down the casing the malformation goes.

That BP grain in the E12 is a very long one from the look of my E12-0s, nearly reaching the end of the casing although I assume the BP portion won't be quite as long in E12s with delay since the delay charge acts as the forward plug instead of a bit of extra pressed BP. A misaligned ram/case will cause uneven compaction along one side of that long grain. When the flame front reaches it, the end burn turns into a progressive burn for long enough to overpressure the nozzle or push the rest of the grain and delay out the front.

Anyone know if there was a typical failure mode with these? Nozzle blowout or a forward blowout?

Edit: oval casing shape is an illusion.

Winston said:

Now, watch, all three will work just fine.

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And that's exactly what happened. Apparently, only the final ramming step, the one that pressed in the clay end plug, was off center. So, there went the chance for a visible clue to the odds of having a CATO with the 08-18-11 lot. No CATOs in the rare instance that you actually WANT one of course.

Some interesting data did come out of this, however. The motor numbers below correspond to the photo of the end plugs above going from left to right. From both the appearance of the clay end plug AND the test data results, #2 and #3 were possibly from the same run on 08-18-11.

Ambient temp - 75F

Burn (sec) Delay (sec)
#1 2.22 9.01
#2 2.28 8.15
#3 2.28 8.03

NAR cert data - burn 2.245s, delay 8.65s ave.