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
Sep 9
DIY Robocars via Twitter
RT @chr1sa: We've got another virtual @DIYRobocars race tomorrow at 9:00am PT. Two dozen autonomous cars will compete, four at a time. Ther…
Sep 4
DIY Robocars via Twitter
Sep 1
DIY Robocars via Twitter
Aug 31
DIY Robocars via Twitter
Aug 31
sam liked Jimmy Oliver's profile
Aug 25
DIY Robocars via Twitter
RT @ExplorerRobocar: Sometimes, I am really a big kid!! Having fun with my virtual RC car on the @diyrobocars track 😜😉, by using the « AR R…
Aug 24
DIY Robocars via Twitter
RT @grepLeigh: @donkey_car @unity3d @TensorFlow ~1050 episodes into training, my agent learned to erratically drive in the left lane. 🤖😆 ht…
Aug 24
DIY Robocars via Twitter
RT @EclipseCyclone: Sweet! high performance #ROS 2 @unity3d #CycloneDDS bridge for @AutowareFdn @SVLSimulator now…
Aug 24
DIY Robocars via Twitter
RT @a1k0n: My car had a lot of trouble getting around the track at the last @diyrobocars event -- only one actual finished lap during the r…
Aug 24
DIY Robocars via Twitter
RT @SmallpixelCar: This is the run time map
Aug 24
DIY Robocars via Twitter
RT @SmallpixelCar: Made a lot progress on Warm Spring Raceways track. Almost finished one lap.
Aug 24
DIY Robocars via Twitter
RT @AntonioRobotics: Super fun time seeing these autonomous cars race at @circuitlaunch for the @diyrobocars quarterly meet up! The demolit…
Aug 15
DIY Robocars via Twitter
RT @a1k0n: I thought my dumb localization code was still working at the new @circuitlaunch track, but it was just *barely* working. I shoul…
Aug 14
DIY Robocars via Twitter
RT @DAVGtech: Recording of entire in person @diyrobocars race today @circuitlaunch. Fast forward a couple hours to go straight to the racin…
Aug 14
DIY Robocars via Twitter
RT @SmallpixelCar: This is the run time map. Very noisy Lidar signal
Aug 14