Simulators and flight skills

Why this matters

Most beginners’ mistakes happen in the first few seconds, such as pushing the stick the wrong way when the nose points at them, or panicking and cutting the throttle. In a simulator you just press restart; with a real drone you may lose the aircraft and injure someone. Systematic practice in a simulator is therefore the first step before touching a real drone.

Choosing a simulator by goal

SITL (software in the loop) runs the real flight-control software on a computer with an aircraft model. On Windows it is easiest to start from the Simulation tab of Mission Planner; QGroundControl works with both PX4 and ArduPilot on Windows, macOS, Linux, Android and iOS.

Passing simulator exercises does not confirm readiness to fly for real, and realistic graphics do not mean forces, wind and batteries are realistically modelled.

Transmitters and stick layouts

Many transmitters can connect to a computer over USB as a joystick, which is separate from the radio protocol used to talk to the receiver on the drone. Before practising, check each axis in turn for correct name, direction and end points. Some charging cables carry power only, so use a data cable.

According to the ArduPilot documentation, Mode 2 uses the left stick for throttle and yaw and the right stick for pitch and roll, while Mode 1 uses the left stick for pitch and yaw and the right for throttle and roll. The PX4 documentation notes that Mode 2 is more popular. A team should use the same mode from practice through to real flight.

When the nose points at you

Sticks command relative to the aircraft, not the pilot. Pushing roll right means “go to the drone’s right”. With the nose pointing away, the drone’s right is your right; with the nose pointing towards you, the drone’s right is your left.

import math

distance = 5.0
for heading in (0, 90, 180, 270):
    move = math.radians(heading + 90)                    # the drone's right
    east = round(distance * math.sin(move), 6) + 0.0        # + 0.0 removes the −0.0 sign
    north = round(distance * math.cos(move), 6) + 0.0
    seen = "right" if east > 0.01 else "left" if east < -0.01 else ("away" if north > 0 else "towards you")
    print(f"heading {heading:>3}°: east {east:+.1f} m, north {north:+.1f} m -> pilot sees it move {seen}")

heading   0°: east +5.0 m, north +0.0 m -> pilot sees it move right
heading  90°: east +0.0 m, north -5.0 m -> pilot sees it move towards you
heading 180°: east -5.0 m, north +0.0 m -> pilot sees it move left
heading 270°: east +0.0 m, north +5.0 m -> pilot sees it move away

Practice with evidence

Record the conditions every time: sim, simulated aircraft, scene, flight mode, sensitivity and any assists. If conditions change, better results may come from an easier scene rather than better skill.

log = [  # (round, crashes, time s, landed on pad, wrong-way roll corrections)
    (1, 3, 95, False, 4), (2, 2, 88, False, 3), (3, 1, 80, True, 2),
    (4, 1, 76, True, 1), (5, 0, 71, True, 1), (6, 0, 69, True, 0),
]
first, last = log[:3], log[3:]
avg = lambda rows, i: sum(r[i] for r in rows) / len(rows)
print(f"rounds 1-3: crashes {avg(first, 1):.1f}, time {avg(first, 2):.0f} s, wrong-way roll {avg(first, 4):.1f}")
print(f"rounds 4-6: crashes {avg(last, 1):.1f}, time {avg(last, 2):.0f} s, wrong-way roll {avg(last, 4):.1f}")
print("landed on the pad:", sum(r[3] for r in log), "of", len(log))

rounds 1-3: crashes 2.0, time 88 s, wrong-way roll 3.0
rounds 4-6: crashes 0.3, time 72 s, wrong-way roll 0.7
landed on the pad: 4 of 6

Module lab

Common mistakes

Summary

• Choose a simulator by goal, FPV, line of sight or SITL, and know each one’s limits
• Mode 2 puts throttle and yaw on the left stick, pitch and roll on the right
• Sticks command relative to the aircraft, so the direction you see depends on heading
• Record conditions and events every round, and compare only rounds with the same conditions

Check your understanding

1. In Mode 2, what does the right stick control?
2. The nose points east (90°) and you push roll right. Which way does the drone go?
3. How does SITL differ from an FPV hand-skills simulator?
4. Round one used Loiter and round two Stabilize. Why can the times not be compared directly?
5. Why use a data cable rather than a charging cable to connect a transmitter as a joystick?