C: Directional Gyro drift - Revision history

Dragonflightdesign at 20:57, 7 January 2020

2020-01-07T20:57:19Z

← Older revision		Revision as of 15:57, 7 January 2020
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	There is only a single directional gyro class in FSX and P3D (PLANE HEADING DEGREES GYRO), so if you have multiple directional gyros they will all drift at the same rate. The following code implements a directional gyro class that can be applied to as many directional gyros as the aircraft needs. All will drift at marginally different rates which match real world standards. ~~The code~~ is copy'n'paste; the only section you need to change is below the 'Implementation' header. This has been tested on an aircraft with three directional gyros (captain, first officer and flight engineer) on a four hour flight. It has also been tested using figures from Ed William's Aviation Formulary ([http://edwilliams.org/avform.htm])		There is only a single directional gyro class in FSX and P3D (PLANE HEADING DEGREES GYRO), so if you have multiple directional gyros they will all drift at the same rate. The following code implements a directional gyro class that can be applied to as many directional gyros as the aircraft needs. All will drift at marginally different rates which match real world standards. This is copy'n'paste code, but check that you haven't already declared the module_vars under different names; the only section you need to change is below the 'Implementation' header. This has been tested on an aircraft with three directional gyros (captain, first officer and flight engineer) on a four hour flight. It has also been tested using figures from Ed William's Aviation Formulary ([http://edwilliams.org/avform.htm])

Dragonflightdesign at 13:14, 5 January 2020

2020-01-05T13:14:56Z

← Older revision		Revision as of 08:14, 5 January 2020
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	// Directional gyro.		// Directional gyro.
	// Calculate the drift to update the display		// Calculate the drift to update the display
	// Offset is the value assigned by the adjustment knob		// Offset is the value assigned by the adjustment knob (0 - 359 degrees)
	// -----------------------------------------------------------------------		// -----------------------------------------------------------------------
	class directional_gyro		class directional_gyro

Dragonflightdesign at 13:13, 5 January 2020

2020-01-05T13:13:12Z

← Older revision		Revision as of 08:13, 5 January 2020
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	{		{
	static double flight_start = 0, prev_lat = 0, prev_lon = 0, prev_lat_deg = 0, prev_lon_deg = 0, flight_progress = 0;		static double flight_start = 0, prev_lat = 0, prev_lon = 0, prev_lat_deg = 0, prev_lon_deg = 0, flight_progress = 0;
	double x = 0, y = 0, er = 0, ln = 0, tw = 0, curr_lat = 0, curr_lon = 0, curr_lat_deg = 0, curr_lon_deg = 0, flight_time = 0, curr_ew = 0, curr_ns = 0, travel_dir = 0;		double x = 0, y = 0, er = 0, ln = 0, tw = 0, curr_lat = 0, curr_lon = 0, curr_lat_deg = 0, curr_lon_deg = 0, flight_time = 0, curr_ew = 0, curr_ns = 0, travel_dir = 0; // Travelling east travel_dir = 1
	// Travelling east = 1
	static double prev_ew = 0; // Previous longitude point was east (prev_ew = 1) or west (prev_ew = 0). See also curr_ew		static double prev_ew = 0; // Previous longitude point was east (prev_ew = 1) or west (prev_ew = 0). See also curr_ew
	static double prev_ns = 0; // Previous longitude point was north (prev_ns = 1) or south (prev_ns = 0). See also curr_ns		static double prev_ns = 0; // Previous longitude point was north (prev_ns = 1) or south (prev_ns = 0). See also curr_ns

Dragonflightdesign: A directional gyro drift class for FSX and all versions of P3D

2020-01-05T13:07:22Z

A directional gyro drift class for FSX and all versions of P3D

← Older revision		Revision as of 08:07, 5 January 2020
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	return dgCard;		return dgCard;
	}		}

			[[category:Aircraft Design]] [[category:Panel and Gauge Design]]

Dragonflightdesign at 12:25, 5 January 2020

2020-01-05T12:25:58Z

← Older revision		Revision as of 07:25, 5 January 2020
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	// Randomise a latitude nut setting between 39 degrees north and 56 degrees north per gyro		// Randomise a latitude nut setting between 39 degrees north and 56 degrees north per gyro
	// '''Make sure this is only done once during aircraft load, otherwise you'll never get a stable setting'''		// '''Make sure this is only done once during aircraft load, otherwise you'll never get a stable setting'''
	latitude_nut1 = getRand(39, 56);		double latitude_nut1 = getRand(39, 56);
	latitude_nut2 = getRand(39, 56);		double latitude_nut2 = getRand(39, 56);
	(etc.)		(etc.)

Dragonflightdesign at 12:21, 5 January 2020

2020-01-05T12:21:05Z

← Older revision		Revision as of 07:21, 5 January 2020
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	double gyro1Update(double knob)		double gyro1Update(double knob)
	{		{
	double x = 0;		double dgCard = 0;

	// Calculate the offset and drift		// Calculate the offset and drift
	x = gyro1.get_hdg(latitude_nut1, knob);		dgCard = gyro1.get_hdg(latitude_nut1, knob);
	// Correct any overshoot or undershoot in degrees		// Correct any overshoot or undershoot in degrees
	if (x < 0)x += 359;		if (dgCard < 0)dgCard += 359;
	if (x > 359)x -= 359;		if (dgCard > 359)dgCard -= 359;

	return x;		return dgCard;
	}		}

Dragonflightdesign: A directional gyro drift class for FSX and all versions of P3D

2020-01-05T12:18:43Z

A directional gyro drift class for FSX and all versions of P3D

← Older revision		Revision as of 07:18, 5 January 2020
Line 297:		Line 297:

	return;		return;
			}

			The alternative to global variables and a global update function is to have a local update function per directional gyro.

			// ----------------------------------------------------------
			// Update the directional gyro drift and display
			// Called from the _update section of the DG gauge
			// 'knob' is the current position of the adjustment knob in degrees (0 - 359)
			// ----------------------------------------------------------
			double gyro1Update(double knob)
			{
			double x = 0;

			// Calculate the offset and drift
			x = gyro1.get_hdg(latitude_nut1, knob);
			// Correct any overshoot or undershoot in degrees
			if (x < 0)x += 359;
			if (x > 359)x -= 359;

			return x;
	}		}

Dragonflightdesign at 12:10, 5 January 2020

2020-01-05T12:10:42Z

← Older revision		Revision as of 07:10, 5 January 2020
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	MODULE_VAR elapsedsecs = { ELAPSED_SECONDS };		MODULE_VAR elapsedsecs = { ELAPSED_SECONDS };
	MODULE_VAR acft_on_gnd = { AIRCRAFT_ON_GROUND };		MODULE_VAR acft_on_gnd = { AIRCRAFT_ON_GROUND };


	// -----------------------------------------------------------------------		// -----------------------------------------------------------------------

Dragonflightdesign at 12:10, 5 January 2020

2020-01-05T12:10:27Z

← Older revision		Revision as of 07:10, 5 January 2020
Line 1:		Line 1:
	There is only a single directional gyro class in FSX and P3D (PLANE HEADING DEGREES GYRO), so if you have multiple directional gyros they will all drift at the same rate. The following code implements a directional gyro class that can be applied to as many directional gyros as the aircraft needs. All will drift at marginally different rates which match real world standards. The code is copy'n'paste; the only section you need to change is below the 'Implementation' header. This has been tested on an aircraft with three directional gyros (captain, first officer and flight engineer) on a four hour flight. It has also been tested using figures from Ed William's Aviation Formulary ([http://edwilliams.org/avform.htm])		There is only a single directional gyro class in FSX and P3D (PLANE HEADING DEGREES GYRO), so if you have multiple directional gyros they will all drift at the same rate. The following code implements a directional gyro class that can be applied to as many directional gyros as the aircraft needs. All will drift at marginally different rates which match real world standards. The code is copy'n'paste; the only section you need to change is below the 'Implementation' header. This has been tested on an aircraft with three directional gyros (captain, first officer and flight engineer) on a four hour flight. It has also been tested using figures from Ed William's Aviation Formulary ([http://edwilliams.org/avform.htm])


			// -----------------------------------------------------------------------
			// FS module_vars
			// -----------------------------------------------------------------------
			MODULE_VAR elapsedsecs = { ELAPSED_SECONDS };
			MODULE_VAR acft_on_gnd = { AIRCRAFT_ON_GROUND };

	// -----------------------------------------------------------------------		// -----------------------------------------------------------------------

Dragonflightdesign at 12:07, 5 January 2020

2020-01-05T12:07:36Z

← Older revision		Revision as of 07:07, 5 January 2020
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	double curr_hdg = 0;		double curr_hdg = 0;

			// Get the current magnetic heading
	curr_hdg = hdg_mag.var_value.n;		curr_hdg = hdg_mag.var_value.n;
			// Instantiate a temporary drift calculation class
	gyro_drift drift;		gyro_drift drift;
			// Calculate the current drift
	dgi_hdg = drift.calc(lat_nut);		dgi_hdg = drift.calc(lat_nut);
			// Calculate the current drift offset from the magnetic heading
	dgi_hdg = dgi_hdg + offset + curr_hdg;		dgi_hdg = dgi_hdg + offset + curr_hdg;