F-22 NX4 EVO — Masterclass Simulator

// LIVE SIM

F-22 Raptor 3D Masterclass Simulator

■ PASSTHROUGH

CAM: ORBIT

ALTITUDE

THROTTLE

ROLL

0.0°

PITCH

0.0°

L-ELEV

1500µs

R-ELEV

1500µs

L-ELEV

0°

R-ELEV

0°

←→Roll ↑↓Pitch W/SThr MMode TabCam RReset

■ Roll(fused) ■ Pitch(fused) ■ Gyro(raw) ■ Accel(raw) ■ Wind

⚙ FLIGHT CONTROLS

AILERON1500µs

ELEVATOR1500µs

THROTTLE0%

WIND GUST0%

FLIGHT MODE M

PASSTHROUGH — raw RC

STABILISE TUNING

MAX ANGLE3°

P GAIN8.0

α FILTER0.980

CAMERA Tab

ORBIT

TOP

CHASE

SIDE

FRONT

KEYBOARD

←→ Roll ↑↓ Pitch WS Throttle (Takeoff > 50%)
M Toggle Mode Tab Camera Space Centre G Gust

// 01

Architecture & Hardware

The F-22 NX4 EVO is a custom digital flight controller for RC delta-wing aircraft running on the ESP8266 with onboard 802.11 Wi-Fi. It implements elevon mixing, sensor fusion, and proportional angle-hold stabilisation in a 250 Hz control loop.

BUG FIXED — Aileron/Pitch Swap: The original simulation had swapped aerodynamic responses. Root cause: the physical F-22 right servo is mechanically reversed (revRight=true). Simulation must apply physR = −(rightOut−1500)/500 before computing moments. Without this, aileron input produces pitch moment and vice-versa.

250

Control Loop

0.98

Filter Coeff

8.0

µs/°

P-Gain

Signal	NodeMCU	GPIO	Dir	Protocol	Notes
MPU-6050 SDA	D2	`GPIO4`	Bidir	I²C Data	Addr 0x68
MPU-6050 SCL	D1	`GPIO5`	Out	I²C Clock	400 kHz fast mode
CH1 Aileron	D7	`GPIO13`	In	RC PWM	1000–2000 µs @ 50 Hz
CH2 Elevator	D8	`GPIO15`	In	RC PWM	1000–2000 µs @ 50 Hz
CH3 Throttle	D5	`GPIO14`	In	RC PWM	1000–2000 µs @ 50 Hz
CH5 Mode	D0	`GPIO16`	In	RC PWM	<1300 PASS · ≥1300 STAB
Left Elevon	D4	`GPIO2`	Out	Servo PWM	50 Hz; revLeft configurable
Right Elevon	D3	`GPIO0`	Out	Servo PWM	50 Hz; revRight=true in hardware!
ESC/Throttle	D6	`GPIO12`	Out	ESC PWM	Direct CH3 passthrough

// 02

Elevon Aerodynamics

The F-22 uses elevons: combined elevator+aileron surfaces. A tailless delta wing has no dedicated horizontal stabiliser, so the single trailing-edge surface pair must generate both pitch and roll simultaneously.

Pitch UP (reflex): Both elevons trailing-edge DOWN → symmetric → increases aft camber → shifts lift behind CoG → nose-up moment.

Roll RIGHT: Left elevon DOWN, right elevon UP → differential lift → rolling moment.

SERVO REVERSAL KEY: Right servo installed physically reversed. Same PWM that moves left elevon DOWN also moves right elevon DOWN — correct for pitch. The reversal creates the symmetric pitch response automatically.

PITCH — Symmetric

ROLL — Differential

// 03

Sensor Fusion & Control Math

3.1 — Complementary Filter

Two sensor sources with complementary error profiles are blended: gyro is fast but drifts; accelerometer is drift-free but noisy. The filter weights them by frequency band.

// α = 0.98, dt = 0.004s (250 Hz)

θ_fused = α·(θ_fused + ω·dt) + (1−α)·θ_accel

// Accel angle via gravity projection

θ_roll = atan2(ay, az) × 180/π
θ_pitch = atan2(−ax, az) × 180/π

Sensor	Fast?	Drifts?	Noisy?
Gyro ±500°/s	✓	✓ Yes	Low
Accel ±4g	✗	✗ Never	High
CF Fused	✓	✓ Corrected	Low

Live Filter Graphs (from simulation)

Roll Axis

Pitch Axis

■ Fused (CF output)■ Gyro-only (drifts!)■ Accel-only (noisy)

3.2 — Corrected Aerodynamic Decoupling

// Apply servo reversal FIRST float physL = (leftOut - 1500) / 500.0f; float physR =-(rightOut - 1500) / 500.0f; // ← NEGATED // Correct decomposition float pitchSig = (physL + physR) * 0.5f; // symmetric float rollSig = (physL - physR) * 0.5f; // differential pitchMoment = pitchSig * PITCH_AUTH; rollMoment = rollSig * ROLL_AUTH;

// Angle-hold P-controller

targetAngle = (RC−1500)/500 × maxStickAngle
error = targetAngle − fusedAngle
correction = error × K_P [µs]

// Elevon mixer

Left = Neutral + PitchCorr + RollCorr
Right = Neutral − PitchCorr + RollCorr

3.3 — Interactive Mixer

MIXER INPUTS

PITCH CORR0

ROLL CORR0

TRIM L0

TRIM R0

Pitch: opposite signs L/R → symmetric → pitch.
Roll: same sign both → differential → roll.

// 04

Software & Web UI

Dual Flight Modes

PASSTHROUGH CH5 < 1300 µs [M key]

Raw RC deviation (±500 µs) passes directly to elevon mixer. IMU updates silently — always primed.

STABILISE CH5 ≥ 1300 µs [M key]

Angle-hold P-controller. Stick maps to ±maxStickAngle° target. Autopilot closes error every 4 ms. Max authority ±400 µs.

EEPROM Layout (64 bytes)

MAGIC 4B TRIM 2B BOOL 1B FLOAT 4B UNUSED

Constant	Default	Increase effect	Decrease effect
`COMP_FILTER_ALPHA`	0.98	More gyro → faster, more drift	More accel → less drift, more noise
`HOLD_P_GAIN`	8.0 µs/°	Stronger → risk oscillation	Weaker → sluggish levelling
`MAX_STICK_ANGLE`	3.0°	More agile, harder to fly	Gentle, strong self-levelling
`MAX_CORRECTION`	400 µs	More autopilot authority	Limits recovery force

Wi-Fi Web UI — 192.168.4.1

09:41●●● ▲

✈ F-22 NX4 EVO

MODE: STABILISE

◈ IMU ANGLES

Roll0.0°

Pitch0.0°

◈ CALIBRATION

Calibrate MPU

◈ SERVO TRIMS

◈ REVERSE FLAGS

Rev Left

✓

Rev Right (hardware!)

Rev Pitch Logic

💾 Save Settings