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Difference between revisions of "Custom blackout system"

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[[Category:Aircraft enhancement]]
 
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[[Category:Nasal howto]]

Revision as of 20:18, 12 November 2016

This is instruction on how to include a more realistic custom mandatory blackout/redout system based of a description of how that worked in a 1979 Langley F-16 simulator. The system is time based, so the longer time you spend at a high G the darker the screen gets.

Per default to clear the darkness you must get below 5G for blackout and above -1.5G for redout. It also features G priming, so that if you for example pull some high Gs for a while and then go negative the redout will take longer to come into effect, and vice versa, as the blood flows to or from the pilots brain.

Install in an aircraft

Copy this code into your aircraft's Nasal folder as blackout.nas file:

###################################################################################
##                                                                               ##
## Improved redout/blackout system for Flightgear                                ##
##                                                                               ##
## Author: Nikolai V. Chr.                                                       ##
##                                                                               ##
## Version 1.0             License: GPL 2.0                                      ##
##                                                                               ##
###################################################################################


var clamp = func(v, min, max) { v < min ? min : v > max ? max : v }

var invert = func (acc) {
	var g_inv = -1 * (acc - 5);
	return g_inv;
}


#
# Customize the values according to the quality of the G-suit the pilot is wearing. The times are in seconds.
#
# According to NASA (1979), this should be the blackout values for F-16:
#
# blackout_onset      =   5;
# blackout_fast       =   9;
# blackout_onset_time = 300;
# blackout_fast_time  =  10;
#
# That means at 9G it will take 10 seconds to blackout completely.
# At 5G it will take 300 seconds.
#

var blackout_onset      =    5;
var blackout_fast       =    9;
var redout_onset        = -1.5;
var redout_fast         =   -4;

var blackout_onset_time =  300;
var blackout_fast_time  =   10;
var redout_onset_time   =   45;
var redout_fast_time    =  7.5;

var fast_time_recover   =    7;
var slow_time_recover   =   15;






## Do not modify anything below this line ##

var fdm = "jsb";
var g1_log = math.log10(1);
var blackout_onset_log = math.log10(blackout_onset);
var blackout_fast_log = math.log10(blackout_fast);
var redout_onset_log = math.log10(invert(redout_onset));
var redout_fast_log = math.log10(invert(redout_fast));

var blackout = 0;
var redout   = 0;



var blackout_loop = func {
	setprop("/sim/rendering/redout/enabled", 0);# disable the Fg default redout/blackout system.
	var dt = getprop("sim/time/delta-sec");
	var g = 0;
	if (fdm == "jsb") {
		# JSBSim
		g = getprop("fdm/jsbsim/accelerations/Nz");
	} else {
		# Yasim
		g = getprop("/accelerations/pilot-g[0]");
	}
	if (g == nil) {
		g = 1;
	}

	var g_log = g <= 1?0:math.log10(g);
	if (g < blackout_onset) {
		# reduce blackout

		var curr_time = fast_time_recover + ((g_log - g1_log) / (blackout_onset_log - g1_log)) * (slow_time_recover - fast_time_recover);

		curr_time = clamp(curr_time, 0, 1000);

		blackout -= (1/curr_time)*dt;

		blackout = clamp(blackout, 0, 1);

	} elsif (g >= blackout_onset) {
		# increase blackout

		var curr_time = math.log10(blackout_onset_time) + ((g_log - blackout_onset_log) / (blackout_fast_log - blackout_onset_log)) * (math.log10(blackout_fast_time) - math.log10(blackout_onset_time));

		curr_time = math.pow(10, curr_time);

		curr_time = clamp(curr_time, 0, 1000);

		blackout += (1/curr_time)*dt;

		blackout = clamp(blackout, 0, 1);

	}

	var g_inv = invert (g);
	var g_inv_log = g_inv <= 1?0:math.log10(g_inv);
	if (g > redout_onset) {
		# reduce redout

		var curr_time = fast_time_recover + ((g_inv_log - g1_log) / (redout_onset_log - g1_log)) * (slow_time_recover - fast_time_recover);

		curr_time = clamp(curr_time, 0, 1000);

		redout -= (1/curr_time)*dt;

		redout = clamp(redout, 0, 1);

	} elsif (g <= redout_onset) {
		# increase redout

		var curr_time = math.log10(redout_onset_time) + ((g_inv_log - redout_onset_log) / (redout_fast_log - redout_onset_log)) * (math.log10(redout_fast_time) - math.log10(redout_onset_time));

		curr_time = math.pow(10, curr_time);

		curr_time = clamp(curr_time, 0, 1000);

		redout += (1/curr_time)*dt;

		redout = clamp(redout, 0, 1);

	}

	var sum = blackout - redout;

	if (getprop("/sim/current-view/internal") == 0) {
		# not inside aircraft
		setprop("/sim/rendering/redout/red", 0);
    	setprop("/sim/rendering/redout/alpha", 0);
	} elsif (sum < 0) {
		setprop("/sim/rendering/redout/red", 1);
    	setprop("/sim/rendering/redout/alpha", -1 * sum);
    } else {
    	setprop("/sim/rendering/redout/red", 0);
    	setprop("/sim/rendering/redout/alpha", sum);
    }

    settimer(blackout_loop, 0);
}


var blackout_init = func {
	fdm = getprop("/sim/flight-model");

	blackout_loop();
}



var blackout_init_listener = setlistener("sim/signals/fdm-initialized", func {
	blackout_init();
	removelistener(blackout_init_listener);
}, 0, 0);


var test = func (blackout_onset, blackout_fast, blackout_onset_time, blackout_fast_time) {
	var blackout_onset_log = math.log10(blackout_onset);
	var blackout_fast_log = math.log10(blackout_fast);

	var g = 5;
	print();
	while(g <= 20) {

		var g_log = g <= 1?0:math.log10(g);

		var curr_time = math.log10(blackout_onset_time) + ((g_log - blackout_onset_log) / (blackout_fast_log - blackout_onset_log)) * (math.log10(blackout_fast_time) - math.log10(blackout_onset_time));

		curr_time = math.pow(10, curr_time);

		curr_time = clamp(curr_time, 0, 1000);

		printf("%0.1f, %0.2f", g, curr_time);

		g += .5;
	}
	print();
}


Then in your aircraft-set.xml file under nasal tags add

<crash>
  <file>Aircraft/[aircraft name here]/Nasal/blackout.nas</file>
</crash>

And that is it. It will work even since blackout/redout is disabled in the flightsim cockpit dialog. If you enable blackout/redout in the dialog, it will revert back to being unselected, the reason is to disable the default blackout system.

Adjusting the numbers

The default numbers are for G-suits anno 1979. We have done alot of research into this and for more modern fighters 1995+ you could set it to something like this:

var blackout_onset      =    5;
var blackout_fast       =    8;
var redout_onset        = -1.5;
var redout_fast         =   -4;

var blackout_onset_time =  300;
var blackout_fast_time  =   30;
var redout_onset_time   =   45;
var redout_fast_time    =  7.5;

Aircraft that use this system

Saab JA-37 Viggen

General Dynamics YF-16

Mirage 2000-5