Gryphon Dynamics X8 motor mount failure. $75000 loss. Red Dragon Movi M15 Zeiss

Discussion in 'Cinestar Misc' started by Davis DiLillo, Apr 16, 2016.

  1. Davis DiLillo

    Davis DiLillo New Member

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    Hey guys! Terrible problem happened in South America. I also posted this in alta 6 sectiom not sure which is a more appropriate sub category for this... But i know lots of people in this forum would be interested in this and I am in need of some oversight. If a moderator would advise and move to where he or she thinks this post belongs. This is very important to me and I believe that alot of the heavy lift professional operators who log many hours on their frames will be intrigued by this discussion also.


    Recently repowered our gryphon dynamics 1100mm x8 v2.0 frame originally with tmotor u7 kv490 and tmotor 80amp escs with tmotor 18in props. We repowered two weeks ago to KDE 5215-435 with 95amp kfe escs and 18in KDE folding props.

    Logged 4 hours of test flights after passing bench tests, everything passed with flying colors. Low ESC temps etc compared to tmotor only 90 degrees Fahrenheit after operation at auw of 47lbs. Before with u7 we would see 165 degrees Fahrenheit. Long flight times little voltage drop. Didn't seem as if there were any high frequency vibrations.

    Anyway here comes the sad part.... During flight, I heard a loud audible plastic impact while hovering over water. Before i could return to inspect, 3 seconds later I heard another pladtix impact and the rear arm dropped like a rock. Drone movi m15 red dragon and Zeiss lens RT motion follow focus system fell into heavy heavy surf. Unrecoverable....

    At first I thought it could be a failure in the folding prop that canabalized the other prop.

    However, after speaking with Patrick at KDE he believes that the Gryphon Dynamics motor mounts are not strong enough for the braking and acceleration of the KDE motors. (They spin over 11,000 rpms.) They claim that the motor mount could have been sheared off during flight or the motor mount screws. This seems plausible to me, however during construction everything was carefully torqued and thread locked. I have heard some sketchy things about flex etc on gryphon dynamics frames. These coaxial motor mounts were over two years old and had seen 250+ hours of operation.

    Has anyone else logged this sort of time on the gryphon frame? Has anyone else experienced this sort of mechanical failure.

    Trying to determine cause of failure to help our industry and my future build. Scared of using gryphon parts again... they look great their functionality has always been fantastic. Just little things, like play in arms, low amperage 3.5mm bullet conmectors and other things that have always bothered me about their quality control. This also makes me wonder about their standards for testing and being transparent about failure points amd recommended maintenance over time. Because that's what's important for a professional logging hours on a frame. They want to trust it. I have no problems replacing things at a regular interval.

    Thanks boys! It's these kind of things that haunt our dreams hahahaha. But we are still early in the industry. Its aviation anyway.... Looks like we are buying the Alta 8 until we find a new frame and flight controller for super heavy lift drone. Looking forward to synapse and closed system flight control :) if there's any positive to take from this loss.
     

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    #1 Davis DiLillo, Apr 16, 2016
    Last edited: Apr 16, 2016
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi MastaDave99999, welcome to the forum.

    Ouch. Sorry to hear of this crash. I'm not quite sure where the posting belongs either, so I'll leave it in this thread right now.

    If it's not too much trouble, would you be kind enough to change your user name to your real first name and last name, please? The reasons for this (and how to do it) are explained here: http://forum.freeflysystems.com/index.php?threads/real-names.497/

    Thanks

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  3. Ozkan Erden

    Ozkan Erden Distributor

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  4. Larkin Carey

    Larkin Carey Member

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    Davis.

    Thanks for posting this here, and for reaching out individually to us knowing that we also fly a GD frame on one of our systems. The collective learning we get to share on this forum and throughout the community is how we all get to push the abilities of this field, and the safety of this industry beyond where any individual has taken it. We sincerely appreciate it.

    I agree with your summary of GD parts. We thoroughly enjoy the folding X8 frame for smaller systems, but there are a few weak links (what you mentioned above, plus the folding mechanism) that should not be trusted with bigger systems. GD is putting a lot of work into making cutting edge components, but they do not seem to be open about problems with their systems and notifying current customers of issues (as compared to FREEFLY who set this forum up purely to discuss all aspects of professional aerial cinema).

    Congrats on the Alta 8! I'm sure you will be really happy with this system! If you are really excited about custom builds still, and want something with more industrial lifting capability using the 5215 motors or other high capacity KDE systems Mid Atlantic Multirotor makes an amazingly solid X8 frame designed by Johnny Beavers, a longtime heavy lift aerial pro cinematographer.

    Again, thanks for sharing your info. Crashes can be devastating, and that sounded like quite an expensive lesson. Happy flying! I hope you can look back on this as a minor bump in a really spectacular aerial career!
     
  5. Fabien Deregel

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    Hi, i am very sad to read this bad news.
    I know the GD frames very well and even if they are not perfect, i can guarantee that the X motor mounts would not collapes so easy, and these are needed to mount U7 size motors.
    The X mounts have each 8 screws support and in no way they can get the screws to shear in normal operation , here is the reason why :
    The Motor mounts are supported by the 2 parts building a X shape from top to lower support. They are " prisoneers" on each side, + the motor mount has another support in reinforcement on the boom.
    So before you would even shear just one of the screws or twist one of the alu parts, you would first shear the motor screws themselve, these are provided by the motor manufacturer.
    I use Gryphon arms for the tests we make with some crazy accelerations / decelerations + use also a solid support on a table bench, i never ever had any problems with standard props including when we have fun making full throttle / stop / ful reverse tests. It supported also the U8 with 28 inches propellers, we anyway damages the motor bearings with hard accelerations and stops. I had many problems with .... folding props..
    Depending on their profile and weight and CG, they are able, or not, to accept hard accelerations and RPM changes. I broke a great number of folding propellers , when making my tests on the bench : props went backward during acceleration or forward during RPM drop and broke instantly when hitting their folding mechanical limits (blade root hitting the alu support) + created very bad unbalance. In these case, we were able to shear down the motor screws... In one case a folding prop set broke with no reason. I did not test the KDE ones but i will give them a try,for sure they do NOT have the system you have i the Alta folding props to avoid them hitting bad forward / backward during accelerations ( there is an o-ring pressing the blade root to allow them to be free to rotate but slow them down during accelerations / decelerations phases) .
    So i would recommend eventualy to give a very close loo to the components if you could get back you hands on them and try to understand exactly what happened .
    It could be also a bad luck with something getting in the props.
    Lastly, KDE motors 5215 / 435 are rated for spinning at 6500 RPM with 18 inches standard props, they spin at 10 000 only with the 15 inches triple blades... If they can sipn 18 inches blades at 11 000 RPM with the 5215 / 435 i would like very much to see this :)))))
    Their motors accelerations are not the strongest ( comes form ESC mainly..) so im' sorry to say that i would definilty first give a check to all components, and check and re check everything from frames to motors, folding props, everything, to make sure you missed nothing.
    The only way to lose an arm during flight or brake a folding arm support is to have a blade breaking in flight causing such an unbalance that it will destroy everything and snap instantly the locks on the arm folding area. If this happens when everything is going fine, then mostly a wrong tightening of these happened.
    Check carefulluy the 2 small locks inside the arm at the folding area and see if they were not broken, if they are broken, there has been i would say 75% probability that a major and sudden unbalance happend during flight.
    Also check the screws fo the folding props if you still have the parts, mayube a wrongly tightetned screws brought one of the blade to get loose and even brake on it's root ?
    MAny possible scenarios here.....
    But in all case: bad day for sure for your rig and hardware :(((((
    Best regards,
    Fabien
     
    #5 Fabien Deregel, May 29, 2016
    Last edited: May 29, 2016
  6. Davis DiLillo

    Davis DiLillo New Member

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    Fabien!

    I think you are spot on.

    I assume that a folding prop threw a prop and the imbalance is what caused the motor mount destruction. It may have been the screws used to mount the motors. I however when I purchased the coaxial motor mounts in 2013 used the screws that Gryphon provided for the motor mounts.

    It may be different now.
     
    Fabien Deregel likes this.
  7. Fabien Deregel

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    Hi David,

    we made a LOT of tests with folding props. One thing i can tell for sure is, they are suitable for fixed wings, or for stable RPM / standard accelerations, but they are absolutly not for heavy lifter in my opinion. At 5000 RPM, the unbalance force you can get if one folding prop does not move forward / backward corectly or stays stuck a bit too long in a folding or leading position is just terrible. Even if the motor stays on the support ( which i doubt if one prop goes away) you will kill the bearings and maybe loose the rotor cage itself or the mount..

    My only advise would be, for big lifters, if you do not have a specific lock or rotation limitation system for your folding blades, just forget about them.. The 5Mn you need to mount / unmount props for transportation are, i think worth the $$$ you have in your machine / camera /gimbal..

    Better use a quick release solid prop ;)

    And for Gryphon Screw, they are damn bad are totally not up to the task, i build all frames with screws class 12.9, and have no issues. If you build a Grypon frame with thread lock on the screws they give, you will be .. screwed ( sorry i could not help i know it's a bad one lol ) and will need to dremelize each one you want to remove for maintenance.. :)

    Best regards,

    Fabien
     
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  8. Kari Ylitalo

    Kari Ylitalo Member

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    I never trusted gryphon boom folding mechanism enough to take it in the sky. Not sure it they have fixed it in later but i saw the disaster happening with that design flaw.
     
  9. Fabien Deregel

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    HI,

    whichever folding boom version you have ( VA or V2), it is necessary to make a reinforcement with 3mm / 4mm carbon + alu clamps to strenghten the area. V2 are much better with side guides / indexes but it's using conical insert / screw and will become slopy with time if there is no reinforcement there.
    The best folding system actualy goes to the Alta for sure, by having the folding system horizontal there is much less possible problem during flight.
    There are other ways to make removable booms anyway with stronger resistance...
    Best regards,
    Fabien
     

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