Wow - Thank you GPS/Telemetry!!!

3DR-B Quad frame

880kv motors

APM 2.0

MP 1.2.9 and Firmware 2.6.1 <-- I think - I already upgraded 2.7.3...

Turnigy 20amp (stock ESC)

4500mah Nano Turnigy battery

Telemetry 3DR Radios 433mhz (so much better than my Xbee's)

Turnigy 9x 2.5ghz, er9 firmware, backlight,lithium battery pack, and 6 position switch :)


Optical Flow

Range Video RX/TX 1.3ghz

My story - I have been tuning this for months and adjusting my configuration. Spread the electronics out a little onto the arms and removed the 3rd level tray and cleared off the 2nd level tray so there was nothing on it. I cut some of the ribs out of the 2nd level tray so the GPS has a nice clear shot up. Got tired of breaking the 3DR legs, so I moved to using wiffle balls as landing gear (works awesome - and you can see it better).

I finally had Sentinel 1 (the quad - what you don't name yours?) tuned. GREAT Loiter, Alt Hold, very stable flight, basic waypoints followed and a solid return home. Auto-Landings never work that great for me and I still like to take control for landings...

I setup the Geofencing. Tested it and it seemed to work well enough doing a RTL when it hit the boundary. I flew a beer can around and all was pretty flawless...

It was around 7:00pm. I began to fly Sentinel 1 fairly aggresivly - a little more than my skill set should have let me. I ended up getting it higher and farther in the in the sky than I wanted to be. GeoFence - where did you go??? So I hit RTL like I have done in the past. Only Sentinel 1 decided it was going on a journey of it's own... It went up higher and higher, while I lost all orientation to which way it was facing. Now to add to the fun -- Warning, Battery at 9.2 volts! it was about 200' up and 1,500' away! Oh Oh! 

I could not get the perspective right and flew it farther away - I switched to stabilize, then loiter and back to RTL - Ahhh good RTL seems to work -- 1,947' feet AWAY!

Warning Battery at 5.8volts! OH NO!

At that point it starts coming down - by the way, over a VERY thick forrest area into a valley. .500 mile away! Warning Battery at 4.7 volts - as it drops below the horizon and disappears into the background view of the mountains and trees into a valley...

I check, and still have a telemetry connection. I then rip through the logs, grab the coordinates, look at the altitude -41'? And see that the quad is very tilted - around 80 degrees...Tree?

I jump into the car and enter the GPS into my iPhone - which keeps correcting to the nearest street! 3 miles by road to then do a 800-1000' hike to it's location in the woods. But now it's getting dark... I get to the location and install a better GPS app for this mission on my phone. I head into the woods with 4 people - hunting for Sentinel 1 - we yell his name, but no one answer - batteries are now dead.

The woods were so thick after 100' in, that it was dark in there, very dark... Looked for 30 minutes and had to give up! It could have been 5 feet in front of me and I would not have seen it...

Went home and waited for daylight - and waited, and waited slept for 1 hour.. and waited, and waited... what a long night.

Got up at sunrise and headed out with Sentinel 1 - Recovery team Alpha! We brought the Jeep so we could drive further into the woods...

We swept the area and found the exact GPS coordinates - it has to be right here!

AND THEN HANGING IN A TREE ABOUT 10 FEET IN FRONT OF ME - My favorite white wiffle balls appeared! Hanging from a tree branch about 10' from the ground was Sentinel 1.

The woods were so thick there that you could only see an opening in the sky about 10'x10' and that's it, the rest is canopy... How lucky I was...

I give him a hug, carry him to the car and bring him home. A quick inspection, then I put in the new battery -- AND IT ALL WORKS! NOT EVEN A BROKEN PROP!!!


Take-aways --- DO NOT fly beyond your experience level - do not get over confident - and remember this is experimental - eventually something will go wrong!

Fly safe my friends!

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Nice post and a happy ending

  • I love the way this was written.
    However, do you know why the geofence didn't work? Why the altitude showed as -41'?
    We should be able to use this to make sure that it never happens to anyone ever again.
    Thanks again for your story!
  • Developer

    Excellent post. Riveting!

This reply was deleted.


DIY Robocars via Twitter
DIY Robocars via Twitter
RT @SmallpixelCar: @a1k0n @diyrobocars I learned from this. This is my speed profile. Looks like I am too conservative on the right side of…
DIY Robocars via Twitter
RT @a1k0n: @SmallpixelCar @diyrobocars Dot color is speed; brighter is faster. Yeah, it has less room to explore in the tighter part, and t…
DIY Robocars via Twitter
RT @a1k0n: I'm gonna try to do proper offline reinforcement learning for @diyrobocars and throw away all my manual parameter tuning for the…
DIY Robocars via Twitter
RT @circuitlaunch: DIY Robocars & Brazilian BBQ - Sat 10/1. Our track combines hairpin curves with an intersection for max danger. Take tha…
DIY Robocars via Twitter
RT @SmallpixelCar: Had an great test today on @RAMS_RC_Club track. However the car starts to drift at 40mph. Some experts recommended to ch…
Sep 11
DIY Robocars via Twitter
RT @gclue_akira: 世界最速 チームtamiyaのaiカー
Sep 10
DIY Robocars via Twitter
RT @DanielChiaJH: Always a good time working on my @diyrobocars car at @circuitlaunch. Still got some work to do if I’m to beat @a1k0n howe…
Sep 10
DIY Robocars via Twitter
RT @SmallpixelCar: My new speed profile for @RAMS_RC_Club track
Sep 10
DIY Robocars via Twitter
RT @SmallpixelCar: Practiced at @RAMS_RC_Club today with my new @ARRMARC car
Aug 28
DIY Robocars via Twitter
Aug 24
DIY Robocars via Twitter
RT @gclue_akira: 柏の葉で走行させてるjetracerの中身 #instantNeRF #jetracer
Jul 4
DIY Robocars via Twitter
Cool web-based self-driving simulator. Click save when the AI does the right thing
Jul 4
DIY Robocars via Twitter
RT @donkey_car: Human-scale Donkey Car! Hope this makes it to a @diyrobocars race
Jun 25
DIY Robocars via Twitter
Jun 25
DIY Robocars via Twitter
Jun 16