I just had my first FPV crash several days ago and thought I would share my experience. I want to explain how and why it happened in the first place, and then how I was able to find the FPV aircraft afterwards in the dark, dense forest & brush.
Hopefully this article will help you avoid making the same FPV beginner mistakes. Even if something completely different happens causing you to crash, you might get a few ideas here of how to locate and retrieve your aircraft afterwards.
You know, one of those perfect evenings... No wind, no bugs, pleasant temperature, and a beautiful sunset.
To top it off, a good buddy of mine came over because he wanted to learn about FPV flying so it seemed a perfect opportunity to show him first hand.
His acreage is about 1 Km away; so I figured I would let him experience a flight over to his house and acreage so he could get the birds eye view of the place. Then we would go for a short scenic flight along the creek, and then on the way back to my place, treat him to some loops and rolls.
Up to this point, I
was following the FPV RC rule book to the letter. I had my flight
planed, I did all the pre-flight checks on my DJI F550 hex rotor,
battery charged & secured, motors & props tight, all connections
good, camera working, GPS lock established, failsafe return to home
GPS coordinates recorded, radio range check a-okay, video feed good &
clear, and aviation radio turned on to monitor any air traffic in the
area. It was going to be a great flight and we were both pretty excited.
To make this an even better experience for him, I decided to let him use the FPV video goggles so he could really enjoy & get a taste of the fully immersive flight experience that goggles provide.
I would pilot the aircraft using my little 7" monitor mounted on the tripod which I had done before (but with tame flying).
This decision to let him use
the goggles while I used the monitor was the main reason for the FPV
crash and I will explain exactly why that decision brought down the
The flight was going great. He loved wearing the goggles and every time I looked over at him, I couldn't help but chuckle a bit. When I banked the aircraft, his head would tilt, if I pitched up or down, his head would tilt back or forward. Now I realized how silly I likely look when I fly with the goggles on; but really who cares when you are having this much fun! The ear to ear grin on his face said it all. He enjoyed seeing his house from 500 feet up as we spent a few minutes flying around the perimeter of his acreage.
As planed, we
then followed the creek back north for 1 km or so, and then turned back
west to come back to my place. The sun had just dipped down behind a
mountain and the sky was a blaze of colors - this is why I fly FPV! It's
at times like this I just wish time could stand still, but of course
that timer on the radio is counting down the seconds so homeward bound I
continued. I basically figured the fight was over at this point as we
were only about 500 meters from my place and I had started my decent.
Now is where things start going very wrong.
Remember, the plan was to throw some aerobatics in toward the end of the flight, so I flipped the Naza from GPS mode to manual mode and it was go-time. Could I induce a little "virtual air sickness" as I tossed the DJI F550 around up there like a rag doll? Well, we never did find out.
Half way though the first loop when a little bit
of video break-up occurred (which usually happens when the FPV antenna
is partially shielded by the DJI F550's body plates), I lost the entire
image on the monitor display screen as the "dreaded blue screen" took over!
I then remembered something very critical that I had completely forgotten about - I cheaped out when I got the monitor not thinking it would be a big deal if the dreaded blue screen ever popped to life with partial video signal break-up.
After all, I would be wearing the video goggles and the spectator would have to simply "ride out" the blue screen until the signal returned to full strength - no big deal.
Problem was, Steve was wearing the goggles. So
the spectator could now see the horizon spinning wildly out of control
as the ground was getting closer, but the dumb-ass piloting the aircraft
could not! In short I had no hope of regaining control if I could not
see what I was doing.
Things happened fast after that. I remember frantically asking him "can you see what's going on"!
All Steve said, is "everything is spinning around"! I immediately switched back to GPS mode and gave full throttle in hopes it would recover, level out, and gain altitude.
I should point
out at 500 meters or so away, it was still too far away to see it in the
sky nor could we hear it, so I really had no idea what was going on.
After I switched to GPS mode and had full throttle on, I asked him "what
are you seeing now". He said "just static". He handed me the goggles
and that lump in my stomach slowly started getting bigger and bigger.
Yep, just an image in the goggles of static, no video feed coming from
the aircraft at all (camera image or OSD telemetry data).
At this point I really had no option but to turn the radio off, thinking maybe, just maybe it's still up there and perhaps during the violent free-fall, something happened to the video transmitter or antenna and it simply stopped transmitting the video signal. If it was still up there, by turning off the radio, it would go into return to home failsafe mode and come back home.
So we waited and listened. As each silent minute passed, I was starting to accept the fact that I had likely just lost $1K worth of FPV multi rotor aircraft. Man that rock in the gut was getting heavy! Steve felt bad, but it certainly wasn't his fault - I was 100% to blame for this FPV crash. After standing there for about 5 minutes with our heads fixated at the darkening sky, and hearing nothing but a few aspen leaves rustling, we both knew it was game over.
it's getting pretty dark out now, we lost it over an area of fairly
dense forest likely 500m2 so finding a half meter size multi-rotor in
all that was going to be the biggest stroke of luck. In fact, I even
talked about just going in for a beer at this point and
not worry about it till the morning. I then realized the battery
would still be working (unless it got all smashed up) and maybe one of
us could see a glow from the LED lighting on it if we were lucky to get
near enough to the spot it crashed.
With all the dumb things I had done up to this point that caused this FPV crash, here is one of the smartest things I did. Before going in search of the downed DJI F550, I remembered to take the video goggles along. You will soon find out why that was such a good call.
So I hiked through
this darkening trail towards the area where we lost the video image. I
kept pulling the goggles over my eyes to see if there was anything
starting to show up. If you have seen my FPV transmitter page, you know I
use 5.8 GHz for my video TX/RX and that 5.8 GHz has very poor penetration
through trees or other solid objects. However, if it was still
transmitting a video signal and I got close enough, I figured there was a
good chance of getting a signal. Sure enough, a faint and dirty image
of grass, leaves, and twigs started fading in and out. I was getting
close! Question is what direction was it.
Now is where having a simple, yet fundamental knowledge of how 5.8 GHz RF works paid big dividends. I simply cupped the back of the FPV receiver antenna on my goggles so the antenna could only "listen for" the video transmitter out in front. My paw on the back side was basically shielding the RF.
In other words, by doing this, I turned my omni directional receiver antenna into a directional antenna. I then just pivoted my body in a 360 degree circle and took note of the direction I was facing when the video image faded in and when it faded out.
This worked so surprisingly well at giving
a directional heading. So simple, so basic, and so accurate. If I had
not taken the time when getting into FPV to understand the basic pros
and cons of the various frequencies that FPV can be transmitted on, I
would not have had the knowledge to figure this simple "directional
antenna" trick out. Thanks Alex Greve, you just likely saved me $1K and
infinitely more important - saved me from trying to explain it to the
wife. Again, if you are thinking of getting into FPV, I highly encourage
you to go over my FPV RC section of my site and watch Alex's video's I
So, I'm doing some good old bushwhacking in the direction of strongest video image as it continued to get clearer and clearer.
At about 75 meters in, I noticed a glow emanating from the forest behind a stand of trees. I couldn't believe it! Sure enough as I got closer and closer, I knew I had found it - phew!
Finding it was of course a huge relief, but now I started to wonder just how badly damaged it was. I figured it was likely going to be in many pieces and cost more to repair than getting another new kit. I was thinking it not only fell out sky at a ridiculous rate of speed, but that it also hit a half dozen or so lodge-pole pines on its way in.
Upon arrival however, instead of seeing a smoking crater in the forest floor with a huge debris field, I was pleasantly greeted to a fully intact DJI F550. Barely a scratch other than two of the 4 spindly landing legs had broken.
Not even one propeller was broken or scratched and it still flew perfectly once I got back home to test it all out. I probably
should have gone out and bought a lottery ticket that night. Talk about
horseshoes. With all the trees around, it landed in this small clearing in
the woods maybe a couple meters in diameter at most.
I honestly don't know how it landed so softly. All I can think is I did switch it into GPS mode and power it to full throttle just in time for it to level out and slow its decent before hitting the ground. Perhaps another hypothesis is as it went down, radio communication was also lost and it went into fail safe mode moments before impact? Maybe it had enough time to at least level out and slow its decent before it ran out of sky? No matter what the reason and how it more or less survived totally intact, it sure gave me an appreciation for the DJI Naza M V2 system and the technology. I really liked my DJI F550 hex rotor before, but now I truly love it!
I hope this FPV Crash experience of mine helps out and lets be FPV RC safe out there. Using good judgment and common sense so we can all enjoy this fun aspect of RC for many years to come :-)