Super Sky Surfer Crash Analysis

Posted by Serge Gonzales on September 21, 2013 at 8:30am

Hi guys,

I need help analyzing my logs and need to confirm if the crash in auto mode was caused by an elevator servo problem or an airspeed problem. This was flown in a remote region far from people and property.

5 minutes into the flight, the aircraft went into full power, nosed down and flipped over due to excessive airspeed. Below is a video of moment things started going wrong. 

https://www.youtube.com/watch?v=KDiQxZ21Zzc&feature=youtu.be

I also attached the .log file

Regards,

Serge G.

2013-09-21 21-08 81.log

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Replies

  • Bill Drake September 25, 2013 at 7:02pm

    OK, for some reason my pics did not upload.  Here they are.  st pic is as described above- shows internal reinforcement.  I've also used external reinforcement in the form of a 3M tape that looks like duct tape but has interwoven fiber- it's 3M™ Scotch® 8959 Filament Tape.  Great stuff.  The entire underside is also covered with the same tape.  The wing "bridge" is reinforced externally with this tape.  If you think about it, as mentioned, the weak point of this plane is the bridge pylons fore and aft of the wing.

    I made a shallow groove in the leading edge of each wing, and laid in some piano wire (you can find at any craft store), and then covered with the decorative green duct tape (but hey, it's still real duct tape, just looks good).  Hopefully this will add some stiffness.

    Note the elevator mod- moved the stock position so that it pulls for "up" elevator. 

    Bottom line is that this is an FPV/cruise platform, not acro...needs to be flown within those tolerances.  On the other end of the speed spectrum, if the plane is a bit heavy then beware wing-tip stalls.  The plane needs lots of altitude to recover.

    On the plus side, the SSS is a payload horse if flown within tolerances.  Needs a BIG area to fly in and out of, with limited obstruction particularly if loaded with batteries, cameras, etc.

    Internal reinforcement.jpg

    Rig.jpg

    Stab.jpg

  • iskess September 21, 2013 at 6:06pm
    I had a situation where my copilot clicked Preflight_Calibration while in auto flight, which resulted in a zero airspeed. The plane pitched down and went full throttle, but it wasn't going to exceeds any parameter limits and cause a crash. My understanding is that the new TECS controller is much better at handling a failed airspeed situation than previously. I'm surprised it pushed you nose down so far beyond the pitch min limit.
    You can see my failure at 4:00 in the video here:http://www.diydrones.com/forum/topics/strange-happenings-on-waypoin...
  • Pieter September 21, 2013 at 9:23am

    This crash is a result of the airspeed measurement dropping to zero half way into the flight. The APM tries to recover by applying nose down and full throttle.

This reply was deleted.