Once you know the rules, you can start to bend them.
Herein, you’ll find some thoughts, advice, and general considerations for long range FPV flying. Flying at range presents a number of challenges, some of which are present when park flying, some of which are entirely unique to going long, but all of which pose a greater danger to your aircraft. These rules are intended to help you maximize your ability to go far while minimizing risk. These rules are inspired by the advice in the back of every Team Blacksheep manual, and refined as I’ve learned tough FPV lessons (for some I got lucky, others I learned the hard way).
Table of Contents:
- Technical Aspects of Long Range
- Battery Management
- Aircraft reliability
- Line of Sight
- Situational Awareness
A note on terminology: I use “home” in this document to mean “the place where you want to safely land your aircraft.”
And finally, if you’re serious about FPV, go get your ham license. Do it now, I’ll be waiting here when you get back.
A note on names: this document was formerly entitled “A Gentleman’s Guide to FPV,” which is a name I found charmingly quaint, but also not-quite-right for what we’re doing here. This is, after all, not exactly a guide, but rather a collection of the bare minimum of things to consider when you’re flying far. If you’re a long range FPV enthusiast already, you’ll likely skim this document in a few minutes, nod a bit, disagree a bit, and be done. But if these are all new ideas to you, they bear some contemplation; it’s not a recipe, but rather a starting point.
Technical Aspects of Long Range
A big part of safely flying long range is technical – these are, in my experience, the key technical aspects.
Your battery is what keeps you in the air. Love it, care for it, and know its intimate details.
Monitor OSD of battery voltage, amp draw, and mAh consumed
Running out of battery is one of the primary risks of long range, and you should always fly with the necessary instruments to know when it’s time to turn around. You’ll need to know about both battery health and consumption if you’re going to maximize your reach and still make it home safely.
Know your battery every flight
When you take off, you should be able to say confidently and correctly exactly what battery you’re flying: How many amp hours is it? What’s its C rating? Is it old enough to sag a little extra? Is it over or under labeled?
Know the mAh value at which you’ll turn around
When you fly far, you want to consume about 80% of your battery in the flight – this is easier on your packs, and gives you room for error. That means that you generally want to turn around having consumed exactly 40% of your pack’s capacity, so you can use another 40% on the way back and land with 20% left in reserve. Flying a 1900 mAh pack means you’ve got 1520 mAh to play with, so you want to turn around at 760 or so.
If you’re flying a hillside, you know you’re keeping some altitude to use on the return trip, you burn less juice on the way home. How much less depends on the conditions, and the best way to know for sure is to measure it. So fly one pack to 40%, and then see how much juice you have left in the tank. On your next pack, you can use a portion of that extra capacity to push further out.
Your radios are your link to your aircraft. Treat them with the respect they deserve.
Fly quality gear
Don’t skimp on radio quality; do your research, and don’t try to trade cost for reliability – it’s a false economy if you lose your aircraft. Two $180 quads is more expensive than one $300 quad.
Learn how radios work, and get your ham license
If you want to go long, do your homework, get your ham license, and study on practical application of radios. All that stuff the ham nerds do applies to us, so learn from their embarrassingly large body of knowledge.
Really good antennas are the key to your long range link. A really good (i.e. as close to 1.0 as possible) axial ratio means you’ll be less susceptible to multipath interference, and your signal won’t lose strength due to signal polarization. At the time of this writing, TrueRC’s x2-air and axii are the best combo I’ve tried.
For control, you’ll generally be using radios that carry further than your video; you may choose to use directional antennas for control, but you generally want the control channel to be more omnidirectional than your video channel. As an example, if you’re using a 12dBi gain video antenna, you’ll probably want to keep your control antenna below 6dBi. That way, you can expect the video link to consistently degrade before the control link, which lets you focus on fewer things.
Position your antennas with great care
Proximity to anything conductive will mess with your antenna’s tune (making it work less well, which is bad) and block your signal (which is far worse). Run an extra-long vtx antenna to get it away from everything, position it so the nulls (which you learned about when you got your ham license – you did that, right?) are pointed at the ground and sky when you’re in normal forward flight, and you’re transmitting clean signal in all directions. Do the same with your control rx antenna.
Yes even crossfire; no do not put it under the arm of your quad, yes I know TBS says that’s fine. Do not bend your immortal T; yes I know you bent your stock dipole and it worked, but dipoles are not the same as diversity. Please stop cargo-culting crossfire antennas, for the love of all that is good in the world.
Take special care not to build such that your antenna works better on your way out than on your way home, lest you lose your aircraft because you literally can’t fly home.
Power output matters
Always take a look at the type of flight you want to achieve, and try and match your RF power levels accordingly. In ideal conditions 25mW of video can get you several miles. Ham radio procedures require you to use only as much transmission power as necessary to accomplish your communication. If you are going for a several mile journey over unpopulated and unrecoverable locations, perhaps 1-2w control link and 800mw on 2.4 video is a good idea. If you’re flying in your local park that same power level is irresponsible. In the case of crossfire, 25mw is plenty for your local park or races, 100mw covers most extended range flights that the average pilot may attempt, and 500mw will give a huge safety blanket over most of the silly things you could dream up. Transmitting more than 500mW with crossfire means you are really pushing the limits of your gear or have a specific target you want to reach that may be risky on a lower power level. Be a responsible RF citizen and think before flying.
Check your frequency before you power on
When you’re in the air, having someone power on and stomp on your signal is terrible, so treat others as you would like to be treated – make sure nobody’s using the frequency before you turn on your transmitter. Turn on your goggles, look to see if the channel is empty, and sweep the area with your directional antenna to get a sense of the RF environment.
More generally, watch the spot you’re planning to fly from for a while. Spend some time before you fly, see what’s happening in the space, and think about how it’ll interact with your flying; maybe it’s RC activity, maybe it’s something else, but you’ll only know if you take the time to observe.
It’s both risky and irresponsible to fly long range with an unreliable aircraft. Do the work to make sure you’re flying safe.
Burn in your builds
The most important thing you can do to make sure an aircraft is reliable is fly it. Fly over a big empty grassy field with nobody in it, and do it until your thumbs bleed. Don’t crash, because a crash can cause damage that takes time to manifest. If you’ve put several hours on your build without anything unexpected happening, you know you’re safer to go long. If you change anything in the build, put some more time on the clock before you go long; the bigger the change, the more time you need to burn in.
While you’re there, explore the whole flight envelope. Fly fast and hard. Fly low and slow. Use this as a chance to get to know your airframe, how it performs, and what sharp edges it has. I once learned my d-term was too high on a quad on my way back from a mountain, because the problem would only manifest when you’re flying forward and down at low throttle; test that kind of thing early, in a situation where it’s easy to bail on the test without crashing.
Burn in your battery combos too – more weight, less weight, extra voltage, etc can cause unexpected things to happen, like your quad desyncing on the wrong side of a river. RIP gapit’s quad. :’(
Buy quality parts
Cheap parts are a false economy; by all means find quality parts that are inexpensive, but don’t put cheap crap on your long range builds.
If you’re trying to do long range on a tight budget, a few things are mandatory: quality radios, a reliable rig, and an OSD with voltage and RSSI. If you don’t have those bare minimal points covered, going long is like rolling the dice, and if you can’t afford to do those things, you probably can’t afford to lose your aircraft either.
Keep it stupidly simple
Any extra complexity is extra stuff that can go wrong. Fancy features are shiny, but complexity generally comes at a reliability cost – you’ll need to do that analysis for every new piece you add to your flight system.
For example, return-to-home is a ridiculously great feature, especially on a wing. I have a buddy who lost both his vtx and his ESC to some kind of unexpected failure when he was a mile out. The inav flight controller glided his wing home and circled it down to a safe crash in a bush near us. That was amazing, and is super worthwhile; however, you need to know inav well, and make sure your build is up to snuff, or inav doing something unexpected could just as well cost you your aircraft. Think hard about the trade-offs.
Keep an eye on wear
Do your motors sound funny? Is your SMA jack hanging on by a couple strands of TPU? Did the tape holding the elevons on your wing deteriorate in all the UV light it’s been exposed to? Fix stuff before it becomes a problem.
Keep and follow a checklist of everything you would like to ensure is functioning correctly before sending a craft out on a journey. This can be as simple as making sure your battery is charged and you’re on the right vtx power level. This could also be much more specific and in depth like ensuring that your motor screws are fully seated, and that your props are brand new and tightened. Maybe you only take off once gps is fully locked in and you’ve tested all control surfaces for full deflections and directions. Any problem you find while you’re still on the ground is a problem avoided in the air. I’ve flown without pre flight checks and ended up having a failsafe due to not checking my radio settings. Luckily it was in an empty snow filled field, it could have easily been a mountain range or river.
A while back, GAPiT made a good point on the FPV Show that we sound pretty full of ourselves when we declare that we’re “FPV Pilots”. That’s a term that commands respect; respect which we haven’t necessarily earned. However, there’s a lot we can learn from pilots, and when we fly long range, applying those lessons will improve your odds of success and your safety margin. Remember that the most aspect of being a pilot is making good choices with the information you have.
In short: prove Gap wrong, and be a pilot.
Line of Sight
Once you can go out far and make it home in one piece, you’ll want to fly close to things. This is where your risk increases dramatically, because a mistake that only takes you half a second can take you out.
Never fly proximity on the same side of the valley you’re on
When you fly close to a hillside, it’s easy to get into a little canyon – if you’re on the other side of the valley, you’ll be able to see deep into the canyon, but if you’re on the same side, there’s a good chance you’ll lose line of sight and failsafe.
Know what’s safe to fly
When you fly proximity against something that’s far away from you, start by scoping out the target. Use binoculars if you can. Use a rangefinder if you have one. Get as much intel on your target as possible, so that once you’re there you know where LoS disappears, and thus when to bail on your dive or cruise.
Use your flight line to measure LoS (Line of Sight)
As you get closer, details will become apparent. Fly straight toward the target, and you’ll be able to pick out little landmarks on the ridge that you can use to find your way to the edges of the target zone.
You can also fly a quad very slowly up a canyon if you think you have LoS, but want to be sure. Be ready to pitch back and punch out the moment video gets dicey.
Bail early, and come back
If you get funky video interference, or something is not exactly like you predicted, fly home. Watch DVR, break out the binoculars, and figure out what happened. More often than not, it’s because the target looks different from the angle you were seeing, and you were losing LoS.
During dives, get your home point in view
If you want to do a proximity dive down a face or deep in a canyon, you can find your home point (assuming your landmarks are really good), and keep that in view relative to the thing you’re diving. Line things up, and you can go super close to the edge of your sight line without crossing it.
To make it home safely, you have to know where home is. There are some habits, skills, and tools to help you.
Turn around and look back home frequently
When you’re on your way out, you should turn around and look back at home. Roughly speaking you want to get a sense of home from each of an increasing set of steps. In meters, I like steps around 10, 50, 200, 500, and then every kilometer or so after that.
Fly a pack or two near your home point before you go long
You can learn a lot about a spot’s peculiarities – wind conditions, RF noise / reflections, landmarks, and all manner of other things – by flying around it. Once you have a good sense of the place, you can push out farther and more easily recognize it. Find big landmarks like lakes, ridgelines, fields, parking lots, etc.
It’s impossible to over-emphasize the criticality of landmarks in FPV navigation. Rivers and roads are useful, because you can follow them back to you. The further away you are, the bigger your landmarks need to be, so find both small things and big things that you can use to find your way home. Remember exactly where you are relative to them.
If you’ve got room in your build, there’s no substitute for that little arrow that points toward home, tells you how far away you are, how high you are, and how fast you’re going.
Google maps is your friend. Think about the thing you want to fly, measure distances, learn landmarks, check what’s nearby, and you’ll enjoy greater success.
3d mapping tools
I use the 3d google earth mode in google maps a ton to plan out my flights. You can line things up and see approximate lines of sight, figure out what landmarks you’re going to be looking for, and generally get ready.
On any given flight, your aircraft may go down; don’t fly over areas where this would cause harm. Things to avoid: roads with anything more than sparse traffic, playgrounds, weddings, funerals, other gatherings of people. In short: plan your flight path so you can look both ways before you cross the street.
Is there full-size air traffic in the area you’re going to fly in? What kind? What’s your plan if it looks like you’re about to share the sky with some humans? Know ahead of time, so if your spotter lets you know you’ve got company you can act immediately rather than taking forever to figure out what the next steps are.
What class of airspace are you flying in? Are there restrictions on landing or taking of from the space you’re in? Are you allowed to control UAVs from the space you’re sitting in? Is it obvious what you’re doing? Will you draw attention on your way in or out? Think about these things early to avoid surprises.
Go out of your way to be nice to people, be accomodating, not irritate them, and show them how amazingly cool FPV is. A little bit of outreach does wonders to improve public opinion in the spots we fly, which in turn protects those spots against the aforementioned legal problems. I make a habit of stopping whatever I’m doing any time I think I’m bothering someone, because I want public opinion about FPV in my area to be positive.
A spare set of goggles or a groundstation screen is an amazing outreach tool.
If environmental conditions are friendly, you’ll generally have a good idea how far a given aircraft can go. Find the spot you want to fly on a map and measure it to know if it’s within reach.
Flying over roads is risky; flying over busy freeways is arguably stupid (I won’t do it, but you make your own choices). If you look at a map, you’ll know this ahead of time.
If you’re going to fly over water, maybe you want to bring a drysuit or a boat. If you’re flying over terrain that’s fairly remote, you might want to know the fastest route to the places you might go down. If you can’t make it home, you’ll also want to know what your best options are for ditching out.
I keep a go bag in my car with a suit of rain gear, knife, lighter, paracord, camelbak, water filter, headlamp, ham radio, etc. If I’m going to do a surprise hike to half a mile from the middle of nowhere, I lock my groundstation in the car and grab that bag. Keeping offline maps loaded on your phone is a good idea too.
I keep a trauma bag in my car, just in case someone gets hurt. At the very least, you should have something to clean and bandage a wound if someone gets lacerated by a prop. You are flying in the middle of nowhere, right?
Don’t go long range if you feel crappy
Make sure you’re in a good state. Fed, rested, and ready to focus.
Knowing what’s going on around your craft, and around your person, can be the key to a safe flight and safe landing.
Fly with a spotter
When you’re going far, having someone keeping eyes on the situation outside the goggles is key. They can run interference if random people show up and ask questions, they can let you know if manned aircraft are in the area, often they can even keep an eye on line of sight for you.
Additionally, your spotter can keep a second set of eyes on the numbers. Make sure they know the battery as well as you do, and they can remind you when you approach your turn-around mah value.
Watch the wind
If you’ve flown a place before, and you know you can make it to a particular target, you may find your range changes with breeze. Particularly in a sidewind, you may end up fighting it both directions, so it’ll cost you range.
A tailwind one way means a headwind the other – ideally you want to fight the headwind first, and then return with a tailwind. If the winds are consistent, you can fly a second pack further into the headwind counting on the tailwind to bring you home, but remember that air is mercurial and may change its mind halfway through your battery.
Watch the clouds
One of my favorite spots to fly is in a valley, and clouds can rip up and down the valley at incredible speeds. Knowing that you can see your way back home, and aren’t fighting to get video signal through too much moisture, is key. Have your spotter keep an eye on them while you’re in the air.
DVR every flight
If you go down, you’ll need to study the recording deeply before you go look for your craft, so be damn sure you have that recording.
Additionally, when you fly progressively further toward your target with different packs, you may find that DVR footage useful to review to understand where your battery is going, etc. If you DVR your flight, then every time you turn around early, you’re collecting data that you can use to plan your next attempt.
Work out a protocol with your spotter
Practice together so they know what you care about in terms of battery, dog walkers, manned aircraft, etc. Make sure that if you’re counting on your spotter you have confirmed with them that they’re sticking around for the whole flight.
Fly with a screen tuned to your signal
Goggles can fail. Receivers can fail. Spotters need some idea what’s going on. If you have a second screen set up so your spotter can see what you see, you can also use that in a pinch. Plus, if you need to swap to 3rd person to land safely, you can swap from goggles to screen, and then from screen to 3rd person, allowing you to transition to brighter sunlight more easily.
I always fly with a Tango because it means there’s a screen for a spotter to look at, but when I fly a proper long range mission I’ll also set up a complete groundstation.
Flying long range is best done with a team of people; a spotter helps with situational awareness, and a couple of other people can be incredibly helpful to back up your spotter.
Author’s Note: this section still needs a bit of work, I apologize for its unpolished character.
As a spotter, it’s your job to ensure the pilot can focus on what’s happening in the moment by providing a second set of eyes on everything else. Know the size of the battery, and ask them when they want to be reminded to turn around. Let them know when they’re approaching the mAh number, and be firm when they reach that number and it’s time for them to come home. Provide context about what’s happening on the ground near you – is it temporarily not safe to land? Let them know. Is there a loud noise? Explain it. Is a fullsize aircraft flying nearby? Tell them exactly where, and how to stay fully out of its path.
Even if you do everything right, you may lose an aircraft. If you make a mistake, your odds of losing an aircraft increase. If you do, don’t beat yourself up about it, plan a recovery mission! I keep a daypack in my car with rain gear, energy bars, a camelbak, water filter, knife, paracord, etc. If I need to take off into the woods, I grab that just in case I need any of those things; what goes in your bag will be dependent on your flying location.
Before you go, rewatch the last of the DVR until you’re sick of it. If you can, take it with you so you can play it back when you’re on scene (goggle DVR is awesome for this).
Take your transmitter with you. If you can turn on a beeper, do that when you think you’re close. Look for video signal – if you still have some, you can use a directional antenna to find your way. The crossfire manual has a stencil you can cut out, tape together, and cover in aluminium foil to make a functional parabolic reflector to improve your direction-finding ability.
If you have a GPS onboard, hopefully you have coordinates – compare the ones on your crossfire tx screen to the ones on the DVR, and see if you can use that to determine the trajectory. Once you decide where you think it landed, plug those coordinates into google maps, and star the location on your phone. As you approach, pull your phone out and use it to walk right up to your downed aircraft.
If you have a GPS but you crashed on the back side of some rocks, take your crossfire tx and an xt30 battery with you – power it up when you get close on the off chance your aircraft is still transmitting crossfire packets that contain the coordinates of the crash.