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The Flight module provides programmers with a method of simulating flight that is both accurate and easy to operate. The module allows programmers to create landable aircraft, including tail-dragger airplanes. The module also contains several useful subroutines.

There are currently two of this module, which are all available in the jsm directory of our GitHub repository:

* Flight4	-	Used to create the flight simulation demo for airplanes.
* FlightH	-	Used to create the flight simulation demo for helicopters.

At the beginning of the program, prior to the importmap, you can load the airplane data using the following command:

< script src="https://PhilCrowther.github.io/Aviation/models/fm2/data/data.js"></script>

After the importmap, you can import the Flight4 module using the following command:

import {Flight,Mod360,PoM360,MaxVal,rotLLD,makMsh} from "https://PhilCrowther.github.io/Aviation/jsm/Flight4.js";

The Flight4 module uses the following variables to store data.

//- Starting Values
let BegPwr = 0;         // Initial Power Percent
let BegSpd = 0;         // Speed (kph)
let BegPos = new THREE.Vector3(0,0,0); // Position (m)
//- Constants
let	DLTime = 1/60;      // Delta Time (1/60 seconds)
let	GrvMPS = 9.80665;   // Gravity (mps)
let	AirDSL = 1.225;     // Density - Sea Level (kg/m3)
//- Variables
let	flight = 0;
let air_ = {
    // General Variables
    DLTime: DLTime,     // Seconds per frame (can vary)
    GrvMPS: GrvMPS,     // Gravity (ups)
    AirDSL: AirDSL,     // Air Density (varies with altitude)
    // Designators
    AirDat: data_,      // Aircraft Data
    // Airplane Rotation: Vertical Angle, Horizontal Angle, Bank Angle
    AirRot: new THREE.Vector3(0,0,0), // Rotation (in degrees)
    AirObj: makMsh(),   // Airplane Object 
    AirPBY: makMsh(),   // Changes in radians
    // Changes to Airplane Pitch Bank and Yaw
    RotDif: new THREE.Vector3(0,0,0), // Change
    // Airplane Speed
    SpdKPH: BegSpd,     // Speed in KPH
    SpdMPS: BegSpd/3.6, // Speed - meters per second
    SpdMPF: (BegSpd/3.6)*DLTime, // Speed - meters per frame	
    // Airplane Map Speed and Position		
    MapSpd: new THREE.Vector3(), // Map Speed (meters)
    MapPos: new THREE.Vector3().copy(BegPos), // Map Position (meters)
    MapSPS: new THREE.Vector3(0,BegPos.y,0), // MSX, MPY, MSZ (meters)	
    // Variables Obtained from Flight
    PwrPct: BegPwr,     // % of Primary Power (0 to 1) (Main and Flight)
    SupPct: 0,          // Percent of Supplemental Power (War Enmergency or Afterburner)
    CfLift: 0,          // Coefficient of Lift (user input) - determines lift
    CfFlap: 0,          // Coefficient of Lift due to flaps (user input)
    FlpPct: 0,          // Percent of Flaps
    LngPct: 0,          // Percent of Landing Gear
    BrkPct: 0,          // Percent of Air Brakes
    SplPct: 0,          // Percent of Spoiler
    AGBank: 0,          // Aileron Bank on Ground
    BrkVal: 0,          // Brakes
    GrdZed: 0,          // Ground level (default)
    GrdFlg: 0,          // Ground Flag (1 = on ground)
    ACPAdj: 0,          // Airplane pitch adjustment
    MovFlg: 0,          // If Sitting on a Moving Object
    // Values for the Selected Airplane Type (obtained from Flight)
    CfLMax: 0,          // Maximum Coefficient of Lift
    FlpCfL: 0,          // Max Flap Cfl (0.2*CfLMax)
    ACMass: 0,          // Airplane Mass
    Weight: 0,          // Used by AutoPilot
    PYBmul: new THREE.Vector3(0,0,0), // Airplane Pitch/Yaw/Bank Multiplier
    BnkMax: 0,          // Maximum bank rate
    // AutoPilot - Additional Variables
    AutoOn: 0,          // Autopilot Flag
    InpKey: new THREE.Vector3(), // Inputs - Keys (replace InpKey)
    OldRot: new THREE.Vector3(), // Old Rotation (radians)
    CfLDif: 0,          // Change in CfL
    MaxBnk: 0,          // Max Bank (display only)
    HdgDif: 0           // Horizontal Turn Rate (display only)
}
// Adjustments
	air_.AirObj.rotation.order = "YXZ";
	air_.AirPBY.rotation.order = "YXZ";
	air_.AirObj.add(air_.AirPBY); // PBY includes air_.ACPAdj

You can use the following command in your initialization section to initialize the Flight4 module:

flight = new Flight(air_);

In your render section, you need to compute the new values for: air_.PwrPct, air_.CfLift (lift), air_.RofDif.z (bank), air_.RofDif.y (yaw). If you are on the ground, you need to compute new values for: air_.BrkVal Once you have done that, you can use the following command to update the airplane position and orientation:

flight.update();

Here are some additional discussions of the Flight Module:

Theory		- Animated examples show the underlying theory.
Programmer Guide		- A Guide for Programmers.
Computations		- The Flight computations.
Validating		- Validating your aircraft performance.