Autopilot

The Autopilot flies the helicopter to a place you pick on a map — climbing, turning and cruising the way a pilot would, within that aircraft’s own limits. It is a separate thing from Autohover: Autohover holds you still, the Autopilot takes you somewhere.

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Using it

1. In the pilot seat, press P. The Pilot Panel opens on its map, in Autopilot mode
2. Click the map to set your destination. Your helicopter and the destination are both marked, and the side card shows the distance, what will happen on arrival and whether your fuel reaches it. Clicking on a marked runway sets its middle as the destination
3. Press ENGAGE. The panel closes and a message tells you how far it is and what will happen at the other end
4. On arrival it hands over to Autohover and holds position. Landing is yours — unless the server has auto-land switched on

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How it flies

• Like a pilot, and to each aircraft’s own limits. It turns nose-first and leans into its turns, and cruises at that helicopter’s own flight.maxAirspeed (on the Ospreys, tiltRotor.helicopterTopSpeed as a helicopter and 85% of flight.maxAirspeed, about 245 knots, on the wing), less when it carries a sling load. In practice it levels out a little below that, where the air starts fighting back. It turns at a rate that suits its tail authority and eases off when it is carrying a sling load
• It looks at the ground ahead. It reads the terrain along the whole route — well over a kilometre out on a long leg — and holds a height that clears the highest ground coming up, with roughly 65 m of margin over it and never less than 40 m above the ground beneath. Trees, buildings, rocks and vehicles on the flight path lift that line further, about 25 m over whatever it finds, before you get there. Your own sling load and the people aboard never count as obstacles. It will not climb above the aircraft’s own ceiling to do it
• It steers round what is in its way. New in v0.4.7: once it is more than about 20 m up, if a hill, building, tower or tree line ahead is more than it can comfortably climb over, it looks for the clearest way past — up to 70° either side — steers into it, and turns back towards the destination once the way ahead is clear
• It goes round big hills on long trips. On a trip of more than 4 km, if a ridge ahead would mean a big climb, it heads up to 60° to one side to go round it, then turns back towards the destination. It doesn’t bother when it is already flying 60 m or more above the ridge, and it still climbs over trees and buildings
• It climbs out first. Engaged low down — in a clearing, next to trees — it goes up onto its safe height before setting off
• It eases off on the way in — a steady slow-down rather than a hard pull-up at the end, starting earlier the faster the aircraft cruises (about 1.5 km out for most) — and hands over to a hover hold at the destination
• It carries on if the pilot gets up. Leaving the pilot seat while the autopilot is flying no longer stops it as long as someone is still aboard, seated or in the cabin: the aircraft flies the rest of the trip, and lands if auto-land is on. With nobody left aboard, the server’s abandoned-aircraft landing takes over after autoPilot.abandonedLandingDelay and sets it down near where it is — except during an Osprey runway landing, which it always finishes
• You can change your mind in flight. Set a new destination while it is already flying and it swings onto the new heading at a steady rate, however big the turn
• It looks after the lights. At night — when it is actually dark, not by the clock — it switches the navigation lights and the dashboard lights on, and the landing light on the way down. When it lets go it switches off only the lights it switched on itself; a light you turned on stays as you left it

While the autopilot is flying, the HUD’s flight-mode badge shows it, so you can tell it apart from Autohover.

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Runways (Ospreys)

New in v0.4.7. Server admins mark runways in game with the runway creator — see Admin Panel → Runways. Nothing is built in for any map: the Ospreys only use runways that have been marked this way, on any map. Saved runways are drawn on the Pilot Panel map with their names. On a runway the CV-22B and MV-22B take off and land like aeroplanes.

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Landing on a runway

The Osprey lands on a runway when the server has auto-land on, the trip is at least 2 km, it is not carrying a sling load, and your destination is within about 1.2 km of a marked runway. The engage message says which runway it will land on, or why it will land as a helicopter instead — for example when it is already too close to line up, which needs about 3–3.5 km of flying from a hover, less the faster it is already going (1.5 km if it is already on the wing).

• It picks the better end. It looks at the ground and the obstacles along both approaches, as a pilot would, and uses the end with the clearer and shorter way in
• It flies the shortest path onto the runway line, re-planning it as it goes, joins the centre line cleanly and holds it, so the nose wheel touches down on it. It banks steeply to turn, as a pilot would, rather than circling round to line up
• Hills in the way? It flies a curved approach down the valley onto a straight final of at least 1 km
• On a long enough runway it lands like an aeroplane — on the wing, nacelles forward, at about 145 knots on the standard Ospreys (well clear of the wing’s 110-knot stall), touching down a short way along the runway. On the standard settings a runway of about 470 m is enough when the way in is clear; trees or buildings before the runway push the touchdown along and need more. The landing gear comes down once it is lined up, about 1.5 km out (about 2 km out on a short-field landing)
• On a long trip to a runway it keeps its cruise speed up for longer and slows down over the last 10 km or so. It flies the long leg at full speed, slows to 170 knots before the runway approach begins (about 15 km out), and flies the turns onto the runway at that speed at most, so they stay tight
• On a shorter runway it makes a short-field landing — slower, with the nacelles part-way up, as slow as about 60–75 knots on the shortest strips. It needs at least about 110 m of clear runway
• Trees, buildings or vehicles near the start of the runway, or on it? It touches down further along, beyond them. If no stretch is long enough to roll out on, it lands vertically on a clear part of the runway instead
• The stall warning stays quiet on its lined-up final, as the approach is flown close to the stall on purpose
• If the approach goes wrong — not settled in time, too far off the line, too low before the runway, or not enough runway left to stop — it goes around: it flies straight out, then comes back for one more approach. If that one misses too, it lands as a helicopter
• After touchdown it rolls out the way a pilot would — power at idle, the nose eased down and the wheel brakes on — slowing steadily along the runway so it stops with room to taxi off before the far end, taxis clear of the runway to the side if there is room, and hands you the controls with the engine still running
• If the pilot leaves the seat during a runway landing, it still finishes the landing

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Taking off from a runway

The Osprey takes off from a runway when the server has auto take-off on and you engage the autopilot on the ground, with the landing gear down and no sling load, for a trip of at least 3 km, parked within about 600 m of a marked runway — beside it on an apron or near either end. The engage message says which runway it will use.

• It picks the end it can climb away from. It checks the ground and anything tall — trees, buildings, power lines — for a few kilometres past the far end, and will not use an end that needs a steep climb to clear what is there
• It taxis like a pilot would — on its wheels, like a car: it needs to roll to turn, reverses or makes a three-point turn where it has to, and stops briefly before changing direction. Its route keeps it and its proprotors clear of trees, buildings, fences and vehicles; it rolls over roads, low slabs and bushes. It slows down with the nacelles up past low obstacles, and stops and waits for players, animals and vehicles in its way. If the route stays blocked for 45 seconds, the autopilot lets go and hands you the controls
• Boxed in? If there is no taxi route, it hops onto the runway as a helicopter, sets down and takes off along it (this needs auto-land on as well). Otherwise it takes off from where it is as a helicopter and tells you why
• It lines up at the very start of the runway, with its tail just inside the end, so the whole runway is there for the take-off. If it is already sitting on the runway facing along it with nearly all of it ahead, it takes off from there
• The take-off roll is at full power. When the runway is long enough — with about 15 percent to spare over the run it needs to lift off — it rolls with the nacelles as far forward as the proprotors can clear the ground and lifts the nose at flying speed. Otherwise it makes a short take-off with the nacelles part-way up, which gets it off the ground much sooner. It also makes a short take-off where a normal climb-out past the end would be steep (more than about a 10 percent climb), and on an end where the run it learned it needs no longer fits. If neither end gives a safe climb-out, it takes off as a helicopter instead and the engage message says why
• Once it is about 30 m up and clear of anything ahead, it raises the gear and carries on to your destination as normal — landing on a runway there too, if there is one
• If it cannot lift off in time, it brakes hard to a stop on the runway and hands you the controls

Touching any flight control takes over at any point, on the ground or in the air, exactly as on any other trip.

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The autopilot learns

The autopilot gets better the more it flies. The server works out each lesson on its own; there is nothing to set up, and it never makes a helicopter faster than its settings allow.

• Arriving at the destination. Each time a helicopter arrives, the server measures how far it carried on past the point where it should have stopped. If a type keeps overshooting, its final approach starts slowing down earlier next time. If it stops neatly, the approach is allowed to be a little quicker. Each helicopter type learns on its own, so a heavy Chinook ends up slowing earlier than a light MH-6
• Touching down on auto-land. The server measures how fast each auto-land actually comes down onto the ground. Landings that hit hard make that type’s final descent gentler, and landings that float make it a little quicker
• Tall obstacles. While the autopilot flies, the server remembers tall buildings and towers more than about 25 m higher than the ground they stand on — the tallest one in each 100 m square, up to 1,500 per map. On later trips, whichever helicopter is flying climbs early enough to clear a remembered obstacle smoothly, instead of only noticing it when it gets close. When one has gone, it is forgotten
• Each runway (Ospreys). What stands along the approaches and the climb-outs (checked again every 7 days), how much runway a take-off needs, and where to aim the touchdown — after two good landings in a row it aims a little earlier, by up to 40 m, and goes back after a poor landing or a go-around. Each end of each runway is learned separately for each Osprey
• Taxi routes (Ospreys). Routes that worked from a parking spot onto a runway are remembered and used again, as long as they are still clear

What it learns is kept in $profile:\CZAutoz_Heli\AutopilotLearning\: autopilot_learning.json (arrivals, landings and tall obstacles), runway_learning.json and taxi_learning.json. The server saves them at most once a minute, and when it shuts down.

• To make it start afresh, stop the server and delete the file. (Delete it while the server is running and it is written back at shutdown.)
• Marking a runway again, or deleting it, clears what was learned about that runway and its taxi routes
• If a file is ever damaged, the server starts it afresh, keeps a copy of the old one in $profile:\CZAutoz_Heli\Backups\ as <name>.unreadable.json, and notes it in the activity log

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Cancelling — you are always in charge

While the map is open your mouse is working the map, not the helicopter, and the autopilot cannot be cancelled by accident from inside it.

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Auto-land

With autoPilot.autoLand switched on, the autopilot finishes the job itself. About a kilometre out it starts looking for somewhere to put down near your destination — the same clear, flat, dry ground check the abandoned-aircraft landing uses. Normally it finds a spot while still running in, so the arrival is one continuous approach: a straight descending line to the pad, slowing on the last stretch, settling level and putting the wheels or skids down properly. The descent is smooth all the way down, and a good spot is never turned down because your own sling load or crew seem to be in the way. On the Ospreys the approach only starts once the nacelles are back in helicopter mode. The engine is left running when it hands you back the controls. If there is nowhere safe near the destination — thick forest, the middle of a town, water — it holds a hover instead and tells you to land it yourself. Every way of cancelling above works during auto-land too.

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Server configuration

These settings are added to existing configs for you, and can be changed live from the Admin Panel.