NAR & TRA Temporary flight restrictions on CTI VMAX motors

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Worsaer

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To our members:

The National Association of Rocketry’s Standards & Testing and Tripoli Rocketry Association’s Tripoli Motor Testing Chairmen are hereby enacting temporary Safety restriction for all Cesaroni Technology, Inc. VMAX reload motors equipped with delay charges.

We have both seen a growing number of VMAX flights using delay only recovery coming in ballistic at our flying fields, due to delay snuffing. It is believed that delay snuffing is likely a result of any extremely high burn rate motor completing its burn with a significant drop in pressure and/or temperature, breaking the burn ‘chain’, extinguishing or ‘snuffing’ the delay slug.

In light of the unpredictable VMAX delay performance and the resulting significant safety issues, we will now require all VMAX motor flights flown at NAR and Tripoli launch sites to have at least one electronic system installed for primary recovery. These electronics need to be able to handle the short G period of these motors to insure “Flight in progress” triggers. The safety restriction will be lifted when the manufacturer has provided documentation to the three motor certification committee chairman which includes the root cause analysis, the corresponding design changes undertaken by the manufacture to address the issue, and implements the necessary changes.

Any questions about this restriction may be sent to your respective organization’s motor test chair

Regards,

Steve Lubliner
NAR Safety Committee Chairman

Paul Holmes
Tripoli Motor Testing Chairman

Deb Koloms
Tripoli President

Ted Cochran
NAR President

John W Lyngdal
NAR Safety Committee
 

Steve Shannon

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Worsaer is Bill Riley, who is also an admin on the Tripoli Forums. This is also posted there.


[emoji1010] Steve Shannon [emoji1010]
 

dixontj93060

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Kudos to NAR and Tripoli for taking actions here to insure safety.
 

grouch

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I am glad to see this for safety sake but it saddens me a little too. I did my cert flight on a H410 and have burned a bunch V Max motors. I hope it gets worked out for the smaller motors at least where electronics may be more trouble than it's worth. I hate to see the current bad press related to CTI.
 

Worsaer

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Worsaer is Bill Riley, who is also an admin on the Tripoli Forums. This is also posted there.


Steve Shannon
Thanks Steve.

If you are a Tripoli member and want to receive important communications such as this via e-mail, I strongly encourage you to log-in to the Tripoli website and subscribe to the member's forum. If you have any questions on how to do this, you can PM me, or drop an email to bvb -at- Tripoli.org.
 

blackbrandt

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Alrighty. :) This honestly won't affect me too much, I fly electronics in everything.
 

AZRxocet

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It would seem that CAR, NAR, and TRA all have somewhat similar testing processes for testing the accuracy of user adjusted delay grains. ImageUploadedByRocketry Forum1464962557.280769.jpgImageUploadedByRocketry Forum1464962577.484322.jpgImageUploadedByRocketry Forum1464962584.193376.jpg
Basically they just make sure it burns within reason to the time it should burn to. However, I would imagine these tests all take place on the ground. I wonder if there's a way to simulate or replicate a real flight condition environment for future tests? Maybe then, we could isolate what, if any, real problem exists. More importantly, find a way to prevent this from happening. Maybe using a different delay grain "formulation" specifically designed just for VMAX could solve the problem?
 

Steve Shannon

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This announcement demonstrates the importance of filing MESS reports. They are not just for catos. One of the categories is "inaccurate delay". By filing a MESS report flyers help identify problems as early as possible when they begin. Problems like this one may happen as a result of a change by a supplier to a manufacturer long after the motor was certified.


[emoji1010] Steve Shannon [emoji1010]
 

DavidMcCann

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Sure , a better test environment is possible. You just need to find someone with a Mach capable windtunnel, who's willing to let you start fires in it. Motor prices won't jump much..... Maybe 2-3,000$ for a J

;)
 

grouch

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You need a centrifuge so the grains can be exposed to a compression load.
 

rharshberger

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Sounds like this is a more latent issue.
AT Warp9 loads have been known for a while to have an issue with delay grains not lighting/staying lit, its not surprising that a motor with a similar burn profile would also have a similar issue.
 

AZRxocet

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Motor prices won't jump much..... Maybe 2-3,000$ for a J

;)
I wouldn't suggest going that far...lol.
Maybe something like adding magnesium flakes to the delay slug mixture...the same stuff they use in those darn candles that won't blow out? I've always flown electronics in my VMAX flights...maybe that's the cheapest reasonable solution after all?
🤔
 

rharshberger

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I wouldn't suggest going that far...lol.
Maybe something like adding magnesium flakes to the delay slug mixture...the same stuff they use in those darn candles that won't blow out? I've always flown electronics in my VMAX flights...maybe that's the cheapest reasonable solution after all?
🤔
Well Eggtimer does sell the Quark kit for $20 so no reason not to fly with electronic deployment. They are cheap and reliable when properly assembled and tested.
 

markjos

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AT Warp9 loads have been known for a while to have an issue with delay grains not lighting/staying lit, its not surprising that a motor with a similar burn profile would also have a similar issue.
Right. Warp9 reload instructions explicitly state that they don't include an ejection charge, must be used with an electronic recovery system, and refer to a "smoke charge," rather than delay grain. I've flown a bunch of the 38mm Warp9 loads, and the "smoke charge" is always unburnt - just barely scorched - after flight.

Pretty fun motors, though!

Mark
 

Donaldsrockets

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Warp-9 loads were plugged right from the get-go due to delay elements getting snuffed out during testing prior to certification. The reason why the delay elements are included is to fill the void in the forward closure.

Although I must say I've flown several G339N loads for the 38/120 in saucers and surprisingly on all of them the delay element ignited and burned through to the end. Maybe the operating pressure of the G isn't as high as the larger ones although it's pretty much on-off just like the rest of them.

I think the burn time is 0.33 seconds IIRC.

Lots of fun BTW and makes for the ultimate now you see it, now you don't effect.:wink:
 
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bobkrech

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...I wonder if there's a way to simulate or replicate a real flight condition environment for future tests? Maybe then, we could isolate what, if any, real problem exists. More importantly, find a way to prevent this from happening. Maybe using a different delay grain "formulation" specifically designed just for VMAX could solve the problem?
NFPA 1125 specifies how motors are to be tested for certification.
  • All 3 organizations test according to NFPA 1125.
  • The Vmax motors all passed the NFPA 1125 certification test standards.

The responsibility to insure that a motor performs as specified falls solely on the manufacturer.
  • When a motor fails to function properly, the certifying authority can decertify the motor or restrict usage.
  • The organizations that recognize the certifications can restrict usage, but can not decertify the motor.
  • In this case, the motor works fine, but the motor ejection does not, hence the prohibition on motor ejection usage.

It does not make economic sense for CTI to have a different delay module for Vmax propellant.
  • AT only offers Warp9 motors without motor ejection.
  • CTI could do the same with Vmax at no cost to the consumer.
  • This makes the most economic sense as the problem is not understood at present, and the testing to simulate the problems would be very expensive.
 

DavidMcCann

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  • The organizations that recognize the certifications can restrict usage, but can not decertify the motor.

Any discussion of ceasing to recognize certifications of one organization if they fail to act on a known and recognized problem?
 

bobkrech

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David, really?

Motor certification is akin to being a notary public in the business world. The certifying authorities, like a notary, are trusted disinterested third party witnesses to a process. Nothing more, nothing less.

Manufacturer's send a small number of motors to the certifying authority with a spec sheet. We burn the motors in a teststand under NFPA 1125 procedures to determine if the motors meet the manufacturer's specifications. If they meet specifications, if the instructions are safe and accurate, and meet government and industry standards, a certification is issued and the motors can be sold retail to the hobby public.

If there is a proven safety issue with a motor, the certifying authorities can and have acted swiftly to make sure the motors can not be used at sanctioned launches. While only the certifying authority can revoke a certification, the other certifying authorities, and even an RSO, can prohibit use of any motor for safety reasons. This has been done in the past, it was just done for Vmax propellant where motor ejection is the primary recovery mode in the US, and certainly will be done in the future. In our club, for example, skid marks are not allowed because they cause grass fires, and as it's not our field, we do not want to loose access to it.

Again David, if it's not reported, it didn't happen. If it happens, and it is reported, the report will be evaluated and the appropriate actions will happen.

Knowledge is power and ignorance is bliss. Can't have it both ways.
 

DavidMcCann

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David, really?
Motor certification is akin to being a notary public in the business world. The certifying authorities, like a notary, are trusted disinterested third party witnesses to a process. Nothing more, nothing less.
I've noticed only 2 of the 3 have taken action. (and neither the certifier) To me that indicates one party may not be disinterested.
 

bobkrech

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Hardly the case. CAR looked into the issue a couple years ago, and after looking at the number of reported Vmax failures back then and after discussing their concerns with CTI, there were not enough failures to raise the level of concern. The recent NAR/TRA prohibition on motor eject only flights is the result of several recent high visibility failures to eject, one which resulted in a large insurance payout. It is not clear whether CAR received the e-mails sent by NAR and TRA prior to the prohibition.

It should be noted that the motor itself is not the issue, but rather the motor ejection failure, so the motor ejection only prohibition is probably the most appropriate action. A similar failure mode was observed during certification with Warp9 and TRA only certified the plugged motor versions of Warp9 motors. However no Vmax motors failed to eject during test stand certifications so Vmax was approved for motor ejection.

The H400 is one of my favorite motors and I personally have not seen an in-flight ejection failure on that motor, but apparently there have been some. The reason for the failure has not been deetermined so a remediation is not available at present except to require electronic deployment as the primary recovery initiator.
 

H_Rocket

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...is the result of several recent high visibility failures to eject, one which resulted in a large insurance payout.
So is there someplace we as members can look at the data that supports the decision? Things I am interested in are:

  • Is this batch related?
  • Is it a specific motor?
  • Is it a specific impulse range?
  • Is there some other metric?
Until I read the above, I had the sensation that this was a knee-jerk response to anecdotal reporting of failures. Like many others, I had never seen or experienced a VMAX failure to eject and was somewhat surprised by the action. As a group of hobbyists, we tend to pride ourselves on being detail oriented and cogent of the data that ensures a satisfactory outcome to our flights. As such, I fail to understand why a blanket restriction was felt necessary on the VMAX with motor ejection without seeing the supporting data. Plus, the restriction essentially bans some VMAX motors almost entirely (E75, F120) as there is not very many configurations that you can build, much less retrofit for the air frames that those motors are suitable for.
 
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Banzai88

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So is there someplace we as members can look at the data that supports the decision? Things I am interested in are:

  • is this batch related?
  • Is it a specific motor?
  • Is it a specific impulse range?
  • Is there some other metric?
Until I read the above, I had the sensation that this was a knee-jerk response to anecdotal reporting of failures. Like many others, I had never seen or experienced a VMAX failure to eject and was somewhat surprised by the action. As a group of hobbyists, we tend to pride ourselves on being detail oriented and cogent of the data that ensures a satisfactory outcome to our flights. As such, I fail to understand why a blanket restriction was felt necessary on the VMAX with motor ejection without seeing the supporting data. Plus, the restriction essentially bans some VMAX motors almost entirely (E75, F120) as there is not very many configurations that you can build, much less retrofit for the air frames that those motors are suitable for.
This.
 

crossfire

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So is there anyway to know how many problem V-Max motors are in the hands of flyers or dealers. I have used 4 CTI H-400 V-Max motors this year all used motor eject with no problems.
 

patelldp

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So is there someplace we as members can look at the data that supports the decision? Things I am interested in are:

  • is this batch related?
  • Is it a specific motor?
  • Is it a specific impulse range?
  • Is there some other metric?
Until I read the above, I had the sensation that this was a knee-jerk response to anecdotal reporting of failures. Like many others, I had never seen or experienced a VMAX failure to eject and was somewhat surprised by the action. As a group of hobbyists, we tend to pride ourselves on being detail oriented and cogent of the data that ensures a satisfactory outcome to our flights. As such, I fail to understand why a blanket restriction was felt necessary on the VMAX with motor ejection without seeing the supporting data. Plus, the restriction essentially bans some VMAX motors almost entirely (E75, F120) as there is not very many configurations that you can build, much less retrofit for the air frames that those motors are suitable for.
Al,

I hear your point. This was a knee jerk reaction to a random but seemingly common problem experienced by many rocketeers. The data isn't there (yet?), but I don't think the organizations wanted to wait around and collect more failure data while risking flyer and public safety. Individual chapters (including one with a very prominent member) had already enacted a ban on motor deployment Vmax. As you know through flying your beloved Sudden Rush on H999's, Aerotech wisely self-imposed a motor deployment ban on their Warp-9 propellant due to poor delay reliability.

Once again, my gut feeling is that we have drag races to blame for additional restrictions. The Dairy Aire Nike Smoke K2045 drag race had many failures, much like every other mass drag race that I have seen or heard of (Ultimate Wildman on N5800, Wildman Competitor 3 on K940, N10,000 at MDRA, L900's at LDRS, etc. etc.). This is what is fresh in everyone's mind and most likely the main culprit for the suspension.

A single failure of any kind during a drag race of more than 2 large rockets is made so much worse due to the distraction factor. Do the right thing...ban drag races and
promote focus on the singular rocket that is launching.
 

mpitfield

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Plus, the restriction essentially bans some VMAX motors almost entirely (E75, F120) as there is not very many configurations that you can build, much less retrofit for the air frames that those motors are suitable for.
I just launched my first E75 at NYPOWER and have another in my motor box. It would be nice if someone came up with an electronic adapter that can screw into the ejection well on the 24mm motors and use an electronic timer initiated by an accelerator to ignite the BP. I know there used to be a device like this but I don't see anything available; possibly this will open up a market for someone to develop something. Otherwise I may never get a chance to use that motor, which would be a shame as it is a really nice little motor.
 

H_Rocket

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Get a LOC Viper-4, it uses 4 x 24mm and do two E75 and two D12-5. It is a really neat flight profile.


Oh wait, electronics were specified. Might not be allowable.
 
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