I have been flying medium range FPV for a couple of months now, here are some of my thoughts how to avoid fpv crashes, or minimize the damage to your plane in crashes. Learning is never ending, so, as I learn more in the future I will keep adding to this list.
Anyway here is a video I made for the FPV flight practice this evening!
Range Tests
50% of the crashes I had so far are due to out of range failure, either lost of video, or RC transmitter signal. To avoid surprises, it’s important to know what the range of your equipment can handle, never ever rely on what people say on the internet, or the product description. The range of your equipment could be longer, or shorter.
Before you do your test, for maximum range you want both antennae (RX and TX) pointing straight up. Having one pointed straight towards the other will drastically cut down range. The loss on cross-polarisathion is actually quite bad (23 dB plus loss from horizontal to vertical which is a LOT actually) – that’s something like a power reduction of 80-90%
You will also find yourself with much better signal when off the ground, because of the multi-path interference from the ground. (same for video signal too!)
Know your places well
Never fly over populated area! It’s not only for the public’s safety, you will also get all sorts of frequency interferences.
If it’s a open area, check on google map, memorize the locations of objects, trees, bushes etc. It will help you identify where you are when flying FPV, and will help you find your plane quicker if you crash.
Check the screws and nuts
This is a very boring job. Unfortunately this is so useful and you would be so grateful when you find a loosened screw or nut. I learned this lesson after a crash due to la prop came loose, which could have been avoided if I check the props every time before I take off (even at battery swaps). Also check all the arms, frame, and motors are securely fixed in position.
Use onbaord GPS
If you are flying medium, long distance FPV (which you can’t handle with flying LOS – line of sight), I would strongly recommend using an onboard GPS OSD, which gives you an rough idea how far you are, and the GPS coordinates of your plane. Just download a GPS coordinate searching app on your phone, and you will be able to find out where the plane is exactly! However, you can’t total rely on the GPS data, sometime it could be well off. That’s why it’s important to know the place you are flying at.
What is even better, is to use GPS enabled flight controller, such as the Crius AIOP, APM2.6 or Naza lite. These boards not allow you to have GPS information displayed on your screen, but also provides the very useful “return to home” feature.
Follow the footpath
If you are new to FPV flying, avoid flying over trees, or bushes, places that you have difficulty to access. If your plane does crash into the bushes, you might have a hard time finding it! I like flying over footpath, or grass, so if anything happens, I can walk directly to it. Especially tall trees, if it got stuck on the branches and you are not a tree climber, you might have to call the firemen to help out, which is not very nice.
Finding your crashed plane
If you are really that unlucky, crashed and unable to figure out where the plane is, use your video signal. Walk closer to the area where the plane might be. There should be another channel on your video receiver that works, but because of the frequency is now different from the one on the transmitter, the range will reduce a lot. This will help us narrow down the search area.
Upgrade your RC transmitter/receiver
I have the Turnigy 9X with stock receiver and transmitter, some people claimed they got up to 1Km range. Unfortunately this is not the case for me. The signal seems to be very unreliable beyond 300 meters (antenna orientation checked). I crashed a couple of times because of this. I decided to give it an upgrade to Frsky DJT. These modules also offer “Failsafe” feature which lower the chance of fatal crash. Telemetry and RSSI would be useful too, to determine the signal condition of radio link.
But again, this is related to my first point, you should really test the max range of your radio, and you should go for the upgrade if the range is not satisfatory.