Viewing performance data

[Volant_Eagle]

Is there a way to display an aircraft's exact in-game performance statistics on the HUD overlay? Things like true airspeed, indicated airspeed, climb rate, altitude, heading, etc?

 

I remember reading in a post somewhere that this is possible. I can't find that post anywhere and I can't find an option for this in Controls or in the info windows. I would like to do some performance comparisons between different aircraft and configurations, but all I have available for viewing speed and climb rate are the cockpit gauges.

[BOO]

Wonder woman view gives you some of that stuff  - IAS most likely. A virtual cokpit export might give you more including a digital readout but I never recall seeing TAS - still with wonder women and a calculator the world is very much your lobster....

[Volant_Eagle]

Wonder woman view? Never heard of this. I also don't know what a "virtual cockpit export" is.

 

If you're referring to what I get with the "toggle cockpit" keybind, that's not what I'm looking for. It is easier to see the data in that mode, but it isn't giving me any data that I don't already have with the cockpit on.

[BENKOE]

There's a thread in the Fulqrum Forum that might have what you're looking for. Some might still remember by its old nickname, the Banana Forum. However, you do need to be registered there to download the missions:

 

Bf109 - Measurement of Air Speed (Fahrt), post #4

 

[koko]

1 hour ago, Volant_Eagle said:

Is there a way to display an aircraft's exact in-game performance statistics on the HUD overlay? Things like true airspeed, indicated airspeed, climb rate, altitude, heading, etc?

 

I remember reading in a post somewhere that this is possible. I can't find that post anywhere and I can't find an option for this in Controls or in the info windows. I would like to do some performance comparisons between different aircraft and configurations, but all I have available for viewing speed and climb rate are the cockpit gauges.

Hey @Volant_Eagle

 

It is possible to display various parameters or implementations derived from multiple parameters using the game’s scripting feature.

For example, the TAS value shown in the image is calculated based on the game’s instrument reading, temperature, altitude, and the standard ISA constants.

 

I am also interested in measuring the performance characteristics of different aircraft, such as maximum speed, acceleration, deceleration, roll acceleration from 0° to 45°, angular velocity, and some other behavior-related aspects of the aircraft in different flight conditions. For this purpose, scripts are an excellent tool.

 

If needed, the results can also be saved as a text file.

[Volant_Eagle]

Thanks @koko! That's what I'm looking for but I'm surprised it would be so complicated. This seems like a very basic game feature that should be displayable with a single button press.

 

It also seems a little needlessly complicated to figure it out TAS by calculating it backwards from IAS. I believe the game itself starts with TAS and needs to calculate the IAS in order to know what to display in cockpit. What do I know though.

 

Is this where you accomplish this:

The FMB is the only place I've seen that mentions "script".

 

I'd really like to know how to use this feature, but it's basically useless to me right now. This is about the maximum extent of my current scripting competence:

 

Is it possible to create a script that would feed you the performance statistics of an aircraft other than the player's aircraft? That would be incredibly useful in determining the performance and capabilities of AI aircraft.

 

[FTC_Rostic]

13 hours ago, Volant_Eagle said:

Is there a way to display an aircraft's exact in-game performance statistics on the HUD overlay? Things like true airspeed, indicated airspeed, climb rate, altitude, heading, etc?

 

I think I can help you with that. Can't promise to do it today. But during the week is most likely.

Just give me all the information you want to see, and I can show bunch of them in Orange Text Message on top of the screen. And send to game chat, so it will be saved in your game log file

I'll create a script for one of existing Quick Missions, so you will be able easily change aircrafts from in game UI.

Ability to change amount of fuel in the tank on the fly through TAB-4 menu can be useful too. Right?

[BENKOE]

On 1/28/2025 at 3:18 AM, Volant_Eagle said:

... < It also seems a little needlessly complicated to figure it out TAS by calculating it backwards from IAS. I believe the game itself starts with TAS and needs to calculate the IAS in order to know what to display in cockpit. > ...

 

You are absolutely right, @Volant_Eagle

 

Before we do any more calculations in this context, it's really important to remember that indicated airspeed is equivalent airspeed, but with the constant mean sea level taken into account. This is true even in the battle area where the WWII aircraft were used.

 

In a WWII single seat fighter the dynamic or impact pressure is the only directly measurable quantity that relates to the aircraft's speed with respect to the air. This directly measurable pressure quantity is used for expressing True Airspeed in metres per second.

 

From this consideration it seems that the pressure altitude, let us call it {H,m}, and a quantity called the altimeter correction, let us call it {D}, are the most convenient parameters with which to represent pressure as speed quantitatively.

 

 Here are a few examples:

Spoiler

(1) Team Fusion Blitz! v5.045, where T,msl = 273,15 + 15° = 288.15 [Kelvin]
350km/h EAS at H,msl ~ 57.9 hPa (Qv) = 350 km/h (rounded) TAS at 0 H.m
350km/h EAS at H,msl ~ 57.9 hPa (Qv) = 452 km/h (rounded) TAS at 5000 H.m
350km/h EAS at H,msl ~ 57.9 hPa (Qv) = 477 km/h (rounded) TAS at 6000 H,m
 

(2) Team Fusion Desert Wings v5.045, where T,msl = 273,15 + 27 = 300.15 [Kelvin]
350km/h EAS at H,msl ~ 57.9 hPa (Qv) = 357 km/h TAS (rounded) at 0 H.m
350km/h EAS at H,msl ~ 57.9 hPa (Qv) = 462 km/h TAS (rounded) at 5000 H.m
350km/h EAS at H,msl ~ 57.9 hPa (Qv) = 488 km/h TAS (rounded) at 6000 H,m

 

The Indicated Airspeed (IAS) would be the Equivalent Airspeed (EAS) if the airspeed indicator were calibrated for exactly current weather conditions in the combat area. However, since airspeed indicators are calibrated for CONSTANT mean sea level air pressure conditions, the IAS will seldom exactly match the EAS conditions.

 

Here is an example for tables, corrected for 25°Celsius at sea level:

Spoiler

For Team Fusion Desert Wings (v5.045), where T(msl) = 300.16

450 km/h EAS at H,msl ~ 57.9 hPa (Qv) = 594 km/h TAS (rounded) at 5000 H,m

the indicator reading  (corrected for 25°Celsius ) 'computes'

95.7 hPa (Qv) ~ 592 km/h TAS ~ 450km/h IAS (rounded) at at 5000 H,m

(Always assuming the airspeed indicator has been calibrated for constant conditions at mean sea level = 273.15 + 15 K.)

 

References:

[1] The use of Pressure Altitude and Altimeter Corrections in Meteorology, John C. Bellamy, 1945
[2] Kennblatt für das Flugzeugmuster Bf109, Baureihe F1 und F2 mit DB601N, Berlin 1941
[3] NACA Reference Publication 1046 - Measurement Of Speed And Altitude, Chapter III (p.25)
[4] NACA Report No.110 - The Altitude Effect On Air Speed Indicators, Part I
[5] NACA Report No.156 - The Altitude Effect On Air Speed Indicators, Part II
[6] NACA Report No.420 - Aircraft Speed Instruments

Edited May 10 by BENKOE
10-May-2015: comments / descriptions moved to spoiler for better reading

[koko]

19 hours ago, Volant_Eagle said:

Is it possible to create a script that would feed you the performance statistics of an aircraft other than the player's aircraft? That would be incredibly useful in determining the performance and capabilities of AI aircraft.

 

@Volant_Eagle 

Unfortunately, I don’t know the answer to that. However, you can activate the autopilot and monitor the parameters if you wish. In some tests, it can be useful to enable the game’s easy mode so you don’t have to worry about trimming the aircraft. I also recommend setting the weather feature in the FMB test mission to no wind 🫡

[Volant_Eagle]

@FTC_Rostic Thanks, that would be great!

 

The most important information to me is TAS, EAS(or CAS, either are close enough for my purposes), and rate of climb. I'm most familiar with mph and fpm as units for these. Metric will work just fine though, and actually having both displayed would be ideal. Throwing in knots would be a bonus but unnecessary. And why do metric cockpits display vertical speed in meters per second anyway? Seems like a very impractical unit for in-flight use. Meters per minute would make a lot more sense.

 

Secondarily but still of great interest to me would be rate of turn in degrees per second.

 

If any of these are possible; rate of acceleration/deceleration, G loading, roll rate, and turn radius would be nice.

 

 

 

Thanks for the detailed explanation @BENKOE! I'm fairly familiar with the general principle and application of these concepts since I fly the real stuff. The airspeed indicator correction for altitude is something I must have brain dumped after flight school/college though. I'm kind of interested in looking into that now (thanks for citing your sources!).

 

 

2 hours ago, koko said:

However, you can activate the autopilot and monitor the parameters if you wish.

Ah, that might do it.

[Dawson]

The script suggestion Koko mentioned will probably give you what you are asking for in real time. Alternatively, have you considered using Tacview?

[koko]

I noticed a certain mistake, so I will check the code and test further to ensure the results are reliable.

Edited January 29 by koko

[Dawson]

removed

Edited January 29 by Dawson

[BENKOE]

9 hours ago, koko said:

I noticed a certain mistake, so I will check the code and test further to ensure the results are reliable.

 Hello koko, the more we share the more we get. In other words share the FMB script, and we all find a solution. 💪

[BENKOE]

Okay, let’s avoid discussing aerodynamics — it’s bound to open a can of worms. Even though it is a flight simulation forum after all, isn't it?

Edited February 2 by BENKOE

[FTC_Rostic]

On 1/29/2025 at 2:10 AM, Volant_Eagle said:

@FTC_Rostic Thanks, that would be great!

 

The most important information to me is TAS, EAS(or CAS, either are close enough for my purposes), and rate of climb. I'm most familiar with mph and fpm as units for these. Metric will work just fine though, and actually having both displayed would be ideal. Throwing in knots would be a bonus but unnecessary. And why do metric cockpits display vertical speed in meters per second anyway? Seems like a very impractical unit for in-flight use. Meters per minute would make a lot more sense.

 

Secondarily but still of great interest to me would be rate of turn in degrees per second.

 

If any of these are possible; rate of acceleration/deceleration, G loading, roll rate, and turn radius would be nice.

 

Hi. I'm sorry for the delay but the mission script will take more time then I expected.

I started working on script. Already have RAW values and saving them to log file in CSV format. So, it can be opened as a table in Excel.

But I need more time to make all the things working right. Maybe mission will be ready next weekend.

[FTC_Rostic]

@Volant_Eagle, sorry for the delay.

Here is a WiP version of mission.

Just unpack it in to "C:\Users\<YourUserName>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\missions\Single" and use "Custom" button to change aircraft.

Or you can unpack it to "C:\Users\<YourUserName>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\mission\Quick" and it will work as quick mission so you can change aircraft there.

 

Use mission menu TAB-4-1 to change units time from metric to imperial. Though IAS is always read from instruments, so units are aircraft dependent.

Use mission menu TAB-4-2-x to change fuel amount in tanks.

Use mission menu TAB-4-3-x to respawn at different altitude.

 

Still no AoA. Will add it later when I figure out how to calculate it.

 

Logs with parameters automatically created in "C:\Users\<YourUserName>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\cache\AcPerfLogscache\"

Log file names given as Log_1.log as  always the newest and Log_9.log is oldest. There will be not more then 9 log files at one time. New log time created each time you start new mission or respawn at new altitude.

000 - aircraft performance.zip

Mission script is a mess due to still WiP. Will try make it look cleaner when AoA added.

[BENKOE]

Hello,

Pitch, Slope and Angle of Attack can be calculated quite simply as follows ...

(For nitpickers only)

 

Spoiler

double v_TAS = plane.getParameter(part.ParameterTypes.Z_VelocityTAS, -1);
// returns TAS vector quantity in metres per second

double x_TAS = plane.getParameter(part.ParameterTypes.Z_VelocityTAS, 0);
// returns TAS scalar quantity x

double y_TAS = plane.getParameter(part.ParameterTypes.Z_VelocityTAS, 1);
// returns TAS scalar quantity y

double z_TAS = plane.getParameter(part.ParameterTypes.Z_VelocityTAS, 2);
// returns TAS scalar quantity z

double v_GS = GroundSpeed(x_TAS, y_TAS);
// returns GS vector quantity in metres per second

double pitch = plane.getParameter(part.ParameterTypes.Z_Orientation, 1) * -1;
double slope = FlightPathAngle(vx, vy, vz);
double aoa   = AngleOfAttack(vx, vy, vz, pitch);


public double GroundSpeed(double vx, double vy) {

        double num = vx * vx + vy * vy;
        double v_GS = Math.Pow(num,0.5);
		return v_GS;
    }		
		
 private double FlightPathAngle(double vx, double vy, double vz) {
        
		// Flight Path Angle = Slope = Angle of Climb (AoC) = Angle of Descend (AoD)
        
		double slope = 0;
        double vxy = GroundSpeed(vx, vy);
        slope = (vz / vxy) * 57.3;
        return slope;
    }
	
private double AngleOfAttack(double vx, double vy, double vz, double pitch) { 
	
	// Angle of Attack (AoA) alpha = Pitch - AoC;
	
	double aoc = FlightPathAngle(vx, vy, vz);
	double aoa = pitch - aoc;
	return aoa;
}

 

 

Edited Saturday at 08:34 AM by BENKOE
10-May-2015: comments / descriptions moved to spoiler for better reading

[FTC_Rostic]

1 hour ago, BENKOE said:

Hello,

Pitch, Slope and Angle of Attack can be calculated quite simply as follows ...

 

Are you sure equations are correct? When stall it gives values like 600, 900, 1400 and other crazy numbers.

[FTC_Rostic]

If I understand correctly AoA calculation should use TAS[x,y,z] vectors  and aircraft orientation[0(heading),1(pitch),2(roll)] angles from game parameters.

 

In your example it is just TAS[x,y,z] and aircraft orientation[1(pitch)].

 

Edited February 9 by FTC_Rostic

[koko]

Hey Rostic,

 

give this a try. I use this formula

double Vx = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 0);
double Vz = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 2);
double aoaDegrees = -Math.Atan2(Vz, Vx) * (180.0 / Math.PI);

[FTC_Rostic]

2 hours ago, koko said:

Hey Rostic,

 

give this a try. I use this formula

double Vx = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 0);
double Vz = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 2);
double aoaDegrees = -Math.Atan2(Vz, Vx) * (180.0 / Math.PI);

 

Thank you! I have no idea why it works. But it works!

It seems Z_VelocityIAS is a true air speed vectors in air in relation to aircraft. So, "0" is prolonged speed vector, "1" sort of side drift, and "2" is ascending/descending vertically (for ideal flat spin only "2" should be non zero). Crazy, why devs called that IAS? So, misleading name...

Edited February 9 by FTC_Rostic

[koko]

 

 

When I started creating scripts some time ago to measure various aircraft performance parameters, I noticed that something didn’t add up.

In the game, IAS = CAS when the wind is set to 0 in the mission settings, so we can derive the TAS speed directly from the IAS value. IAS and TAS speeds should be the same at sea level. In the image, the leftmost IAS value represents the game’s I_VelocityIAS, -1 value. TAS calc is the TAS speed calculated from the IAS value using ISA standard constants. The rightmost TAS Z value corresponds to the game’s Z_VelocityTAS, -1 value, and the IAS calc value is the IAS derived from it using the ISA conversion formula.

 

The game’s built-in values don’t seem to match, meaning one of them must be incorrect. I conducted several tests and found that TAS Z is accurate, so IAS must be incorrect. As seen in the image, at an altitude of 1.2 meters, the difference is 7.1 km/h. (I happened to take the screenshot just as a propeller blade touched the water. The aircraft was still level, and I could see two blades, one of which had its tip bent)😄

 

Another issue I noticed is that the game’s external temperature measurement parameter does not scale according to the ISA standard. At sea level, the values match, but at higher altitudes, the discrepancy becomes significant enough to affect air pressure calculations, which then impacts air density and other related computations. Because of this, I have started using an ISA-based ‘thermometer,’ and now the values align correctly with external calculations at all altitudes.

Does anyone have any information or any idea about what might be causing the IAS speed and/or thermometer ‘measurement errors’?

 

 

[FTC_Rostic]

Here is a updated version of mission. Added angle of attack and acceleration.

Thanks @koko and @BENKOE for your help and advises.

 

BLITZmission_aircraft_performance - project.zip

 

000 - aircraft performance - mission - 2502092337.zip

 

Just unpack "* - mission - *"  archive in to "C:\Users\<YourUserName>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\missions\Single" and use "Custom" button to change aircraft.

Or you can unpack it to "C:\Users\<YourUserName>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\mission\Quick" and it will work as quick mission so you can change aircraft there.

 

Use mission menu TAB-4-1 to change units time from metric to imperial. Though IAS is always read from instruments, so units are aircraft dependent.

Use mission menu TAB-4-2-x to change fuel amount in tanks.

Use mission menu TAB-4-3-x to respawn at different altitude.

 

 

 

Logs with parameters automatically created in "C:\Users\<YourUserName>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\cache\AcPerfLogscache\"

Log file names given as Log_1.log as  always the newest and Log_9.log is oldest. There will be not more then 9 log files at one time. New log time created each time you start new mission or respawn at new altitude.

 

You can add or remove aircraft parameters in code by simple changing true to false and vise versa.

.

No more updates planned. Maybe turn rate... but that any one can calculate using data in log file. Just use heading and game time

[Volant_Eagle]

@FTC_Rostic Thanks a ton for this! This will be very useful and I appreciate all the work you put into it.

 

 

9 hours ago, FTC_Rostic said:

You can add or remove aircraft parameters in code by simple changing true to false and vise versa.

I can't open .cs files. What program do you use for this?

 

9 hours ago, FTC_Rostic said:

but that any one can calculate using data in log file.

True... but then I have to do math... and I have no idea how to read this:

...and even if I did know how to read it, call me lazy, but it looks like too much hassle to bother with. 😏

[Volant_Eagle]

13 hours ago, koko said:

double Vx = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 0); double Vz = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 2); double aoaDegrees = -Math.Atan2(Vz, Vx) * (180.0 / Math.PI);

Not that it matters much, but is this producing an angle of attack relative to the longitudinal axis of the airframe, or the average cord line of the wing?

 

Most aircraft are going to have the wing mounted at some angle of incidence relative to the longitudinal axis. And technically AoA needs to be relative to the wing and not the longitudinal axis.

 

I don't really care which way this formula works. I'm just curious for my own understanding. For basically every aircraft other than the Whitley, there isn't enough difference to make a difference in practical terms.

 

The only thing that makes me slightly suspicious is how most aircraft are indicating 0 degrees AoA in level flight. Maybe it's just rounding down from a fraction of a degree though. And it is possible to have 0 degree geometric AoA, while still having a positive effective AoA due to camber.

 

Otherwise this formula seems to be working perfectly. Aircraft seem to always stall at the same AoA, regardless of airspeed, attitude, or altitude. And the angle at which they stall also seems reasonable. The Hurricane stalling at roughly around 17 degrees for instance.

 

 

I also had no idea you could subtract math out of a math equation 😄

 

 

10 hours ago, koko said:

In the game, IAS = CAS when the wind is set to 0

Pretty certain this is incorrect. At least I hope so or there's something wrong with the game physics.

 

The difference between IAS and CAS has nothing to do with wind. Once an aircraft is airborne, the aircraft is now moving along with the steady state velocity of that airmass. So from the airplane's perspective, flying in a 0 knot wind is no different than flying in a 100 knot wind. The only speed effected by wind is groundspeed. Wind has no effect on IAS, CAS, EAS or TAS (disregarding momentary gusts where aircraft momentum comes into play).

 

IAS is including instrument error which in real life will be different for each individual aircraft type. The error will also not always be the same in all phases of flight for a given aircraft. It might be pretty close at one airspeed and way off at another.

 

As I vaguely recall from previous posts by Buzzsaw on this forum, CloD does in fact have a built in indicator error, meaning IAS is actually IAS and not CAS. However, the IAS error in CloD is very simplified. I believe it's just the same blanket error value for all airspeed indicators on all aircraft. This is not very realistic but at least the feature is there. And I have to grant that for some aircraft the correct error values may be lost to time anyway.

 

10 hours ago, koko said:

Here's my stab at what might be going on in this data strip:

 

"IAS: 255.8 km/h" is being pulled right from the game IAS and thus has an error factor.

"TAS calc: 255.8 km/h" is being calculated from the in-game IAS which is incorrect. TAS needs to be calculated from CAS (or EAS) and IAS is not CAS.

"IAS: calc: 272.9 km/h" is being calculated using a formula that is assuming no instrument error, therefore this isn't IAS, it's CAS.

"TAS Z: 272.9 km/h" is being pulled directly from the game and is actually TAS.

 

If this assessment is correct, we could then deduce the error factor added by CloD to create IAS must be around negative 17.1 km/h. (at least at this speed and altitude. I have no idea if the error system in CloD is complex enough to change this value with speed, altitude, or AoA like would happen in real. I highly doubt it though.)

 

 

[Volant_Eagle]

12 hours ago, FTC_Rostic said:

It seems Z_VelocityIAS is a true air speed vectors in air in relation to aircraft.

Maybe not. If this a separate value in the game: 

11 hours ago, koko said:

Z_VelocityTAS,

then I would assume that Z_VelocityTAS must be TAS, and Z_VelocityIAS must be something else. What needs to be cleared up is whether Z_VelocityIAS has an indicator error added to it or not. (Is it IAS or CAS).

 

15 hours ago, koko said:

double Vx = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 0); double Vz = aircraft.getParameter(part.ParameterTypes.Z_VelocityIAS, 2); double aoaDegrees = -Math.Atan2(Vz, Vx) * (180.0 / Math.PI);

Would it be better to run this with VelocityTAS instead of VelocityIAS? It seems to be working fine as is, but just a thought.

[FTC_Rostic]

2 hours ago, Volant_Eagle said:

@FTC_Rostic Thanks a ton for this! This will be very useful and I appreciate all the work you put into it.

 

 

I can't open .cs files. What program do you use for this?

 

True... but then I have to do math... and I have no idea how to read this:

...and even if I did know how to read it, call me lazy, but it looks like too much hassle to bother with. 😏

 

To open .cs file use notepad++ or any text editor.

 

You have to make copy of .log file and rename it .csv like log_1.csv

After that excel or any other table processor all should open it.

[koko]

7 hours ago, Volant_Eagle said:

 

 

 

@Volant_Eagle 

Thanks for the correction regarding the IAS-CAS matter 👍 my mistake.

 

Your assumption that Z_VelocityIAS produces the CAS speed seems to be correct based on the image. The difference between Z_VelocityTAS and Z_VelocityIAS is that IAS accounts for wind: “Subtype 0 shows aerial flow along machine’s X-axis” vs “Subtype 0 shows machine’s speed along world’s X-coordinate

 

Could we conclude from this that Z_VelocityIAS can be used for test flights in 0-wind conditions? The images were taken under 0-wind conditions.

 

I tested the AoA readings of the 109F-4, Spitfire Va, Hurricane II, Kittyhawk, and Martlet with the throttle at 95% in all aircraft. The AoA values ranged approximately between -0.38° and -0.46°, depending on the aircraft, except for the Martlet, which had a value of -0.6°.

[koko]

9 hours ago, Volant_Eagle said:

Would it be better to run this with VelocityTAS instead of VelocityIAS? It seems to be working fine as is, but just a thought.

 

This is not possible because Z_VelocityTAS represents a stable world coordinate system in which the aircraft moves, whereas the Z_VelocityIAS coordinate system moves with the aircraft along all its axes. Using Z_VelocityTAS, the AoA would indeed show 0° in stable level flight, but not in any other flight condition.

[BENKOE]

Hello all,

the following FMB script values are useful as a first step airspeed measurement:

 

1.
double outerAirTemp = playerplane.getParameter(part.ParameterTypes.Z_AmbientAirTemperature, -1),
where <Z_AmbientAirTemperature> reveales Outer Air Temperature as quantity in degrees Kelvin.

 

2.
double geometricAlt = playerplane.getParameter(part.ParameterTypes.Z_AltitudeMSL, -1),
where <Z_AltitudeMSL> reveales the geometric altitude as quantity in meteres above sea level.
It is very important to convert the geometric altitude (Z_AltitudeMSL), which is the actual virtual world 'tape measure metric' altitude above sea level, into geopotential altitude. The latter is a pressure altitude that is consistent with the assumption of a constant value of gravity (g=9.80665). Actually, it looks like Team Fusion Company is using 'tape measure metric' altitude as geopotential altitude.

Edit: An important type of geopotential height is pressure altitude, which is based on a standard atmospheric model for temperature as a function of pressure. One particular model, the International Standard Atmosphere, is what all aircraft altimeters use to relate static pressure measurements on an aircraft to a corresponding pressure altitude scale. 

3.
double trueAirspeed = playerplane.getParameter(part.ParameterTypes.Z_Velocity TAS, -1),
where <Z_VelocityTAS> is the TRUE AIRSPEED in metres per second (m/s) for all aircraft in the game, including all aircraft without human pilots, commonly known to the TFC community as drones or 'AI'. Please remember, in a WWII single seat fighter the dynamic or impact pressure is the only directly measurable quantity that relates to the aircraft's speed with respect to the air. The pressure generated by the Pitot-Static tube may be expressed as TRUE AIRSPEED at current altitude based on the relationship: TAS² = (2 x q) / rho{t,h}

4.
double indicatedAirspeed = playerplane.getParameter(part.ParameterTypes.I_VelocityIAS, -1),
Where <I_VelocityIAS> reveales INDICATED AIRSPEED as quantity in kilometers per hour (km/h), or as quantity in miles per hour (km/h),
for aircraft with human pilots only. All airspeed indicators in the game should depend on the pitot static tubes for their operation.
Please remember, in a WWII single seat fighter the dynamic or impact pressure is the only directly measurable quantity that relates to the aircraft's speed with respect to the air. The pressure generated by the Pitot-Static tube may be expressed as INDICATED AIRSPEED at current altitude based on the relationship: IAS² = (2 x q) / rho{T,SL}
From this consideration it seems that the pressure altitude, let us call it geopotential altitude {H,m}, and a quantity called the altimeter correction, let us call it {D}, are the most convenient parameters with which to represent pressure as speed quantitatively.

Here is an example for a German WWII airspeed indicator corrected for 25°Celsius at sea level:

450 km/h EAS at H,msl ~ 57.9 hPa (Qv) = 594 km/h TAS (rounded) at 5000 H,m

the indicator (corrected for 25°Celsius ) shows

95.7 hPa (Qv) ~ 592 km/h TAS ~ 450km/h IAS (rounded) at at 5000 H,m

 

Quote

< Soon, here you will see the c# method for the example above >

 

Again, it is absolutely crucial to understand that WWII airspeed indicators are corrected for constant mean air pressure conditions at sea level in the battle area where the WWII aircraft were used. Unfortunately, it seems that Team Fusion Company has a different idea of airspeed measurement ...

 

References:
[1] The use of Pressure Altitude and Altimeter Corrections in Meteorology, John C. Bellamy, 1945
[2] Manual of the US Standard Atmosphere, 1962
[3] International Standard Atmosphere, 1976
[4] NACA Reference Publication 1046 - Measurement Of Speed And Altitude, Chapter III (p.25)
[5] NACA Report No.110 - The Altitude Effect On Air Speed Indicators, Part I
[6] NACA Report No.156 - The Altitude Effect On Air Speed Indicators, Part II
[7] NACA Report No.420 - Aircraft Speed Instruments
[8] NACA TM No.913 - Measurement Of The True Dynamic And Static Pressures In Flight, Georg Kiel, 1939
[9] NACA TM No.917 - The Effect Of Compressibility On The Pressure Reading Of A Prandtl Pitot Tube, O. Walchner 1939
[10] Fundamentals Of Aerodynamics, John_Anderson, 2017

Edited February 11 by BENKOE

[Volant_Eagle]

Pardon me if my statements seem overly emphatic or my questions annoyingly pointed and detailed. It's just seeming more and more apparent to me that I cannot assume that any terminology used in the coding of this game has necessarily anything to do with the actual aerodynamic terminology of the same name. That is not to say I necessarily think the game is modeling anything incorrectly, I'm just saying that two completely different and very complicated subjects are being discussed here (computer simulation coding and aeronautical physics), and it's very easy confuse the two in communication or assume one functions like the other without confirming that it does.

 

Aeronautical physics is something that is pretty well understood and the terminology is more or less set in stone. "True Airspeed(TAS)", "Indicated Airspeed(IAS)", "Angle of Attack(AoA or alpha)", "Dynamic Pressure (q)", "Air Density (rho)", etc; all have one and only one meaning and definition in regards to actual aerodynamics.

 

Flight simulators are trying to create a dynamic 3D representation of vehicles in flight that mimics as closely as possible how the real vehicles fly through real air made of real atoms. All that matters is that the output matches what would've happened in real. There are probably a million and one different ways to program a computer to produce the same result. There are different coding languages, different game engines, and different methods for calculating certain parameters. Developers can't follow aerodynamic formulas to a T in every situation. Those formulas are based on representing reality, not a virtual world made of ones and zeros. You would basically have to simulate everything using simulated atoms in order for a simulation to run using actual aerodynamic formulas in every case. That is way beyond the capability of most if not all computers.

 

So, especially when the simulator is a game that will be played on an average home PC, developers need to use a somewhat different and simplified approach in the background. They just need to create a set of protocols that a computer will understand, and more or less "skip to the end", spitting out a result in real time that is close enough to reality for that simulator's purposes. There is more than one way to formulate a program to get each result, and the terminology used for the components of whatever formula they decide on are completely arbitrary. If they wanted to, they could label what an aeronautical engineer might call "True Airspeed" something else like "flubber" or "potato" in their code. Obviously they wouldn't use that particular example, both to avoid confusing themselves and avoid having their boss question their sanity when reviewing the code, but the point is that they could.

 

They will probably try to use terminology that is similar to that used in the same real life scenario they are simulating. But depending on their game engine and their workflow, a particular term might need to be used or reused in areas where it does not correctly correlate with the aerodynamic term of the same name. The more this discussion goes on it seems more and more apparent that terms like "TAS" and "IAS" have exactly that problem in this game. When these acronyms appear in the game code, it is not safe to just assume they mean the same thing as the actual aerodynamic terms of the same name.

 

Sorry for the long rant, I was half trying to work out my own thoughts, but half trying to verify I'm on the same page with you guys. I'm nearly a complete ignoramus in regards to coding, and all of you seem quite experienced with it. My aerodynamics experience is also more practical than technical, so I keep needing to go back verify what certain terms are, and that I do in fact have certain concepts straight in my head.

 

 

If someone wouldn't mind humoring me, could I get a piece by piece explanation of what "Z_VelocityTAS, -1" or "I_VelocityIAS, -1" are supposed to mean in the game code? What does "Z" mean as opposed to "I"? Is there anything particular to know about "Velocity"? What does the game think "TAS" is as opposed to "IAS"? What does the ", -1" or any other number mean here?

 

Is there a document somewhere I can reference to read these explanations for myself?

 

 

On 2/10/2025 at 11:28 AM, koko said:

Your assumption that Z_VelocityIAS produces the CAS speed seems to be correct based on the image. The difference between Z_VelocityTAS and Z_VelocityIAS is that IAS accounts for wind: “Subtype 0 shows aerial flow along machine’s X-axis” vs “Subtype 0 shows machine’s speed along world’s X-coordinate

 

Could we conclude from this that Z_VelocityIAS can be used for test flights in 0-wind conditions? The images were taken under 0-wind conditions.

That first paragraph seems like a contradiction to me. If Z_VelocityIAS takes wind into account, then it necessarily cannot be CAS or any other sort of airspeed. Wind is always irrelevant to airspeeds. If wind is added into the equation then it's now a ground speed and not an airspeed. For any parameter to be what a pilot or aero engineer would call "airspeed", it necessarily needs to be completely independent of how much wind is in the game.

 

If Z_VelocityIAS does take wind into account, then we might still be able to use it for airspeed calculations, but only if the in-game wind is 0. It would still be very important to first verify that it's representing true ground speed and can therefore be used in place of true airspeed.

 

On 2/10/2025 at 11:28 AM, koko said:

“Subtype 0 shows aerial flow along machine’s X-axis” vs “Subtype 0 shows machine’s speed along world’s X-coordinate

These definitions of these terms are very eye opening as to what they represent, but still leave a lot of loose ends.

 

"aerial flow along machine's X-axis" definitely sounds like an airspeed to me. It just doesn't clarify what type of airspeed (IAS, CAS, EAS, or TAS).

 

"shows machine's speed along world's X-coordinate" -Does this mean if traveling 300kph along the x-coordinate this value is 300kph, but if traveling 300kph perpendicular to the x-coordinate this value is 0? If so, this is ground speed along just one axis of the world.

 

If the difference between TAS and IAS in the code is the difference between "flow along machine's _-axis" and "speed along world's _-coordinate", then these terms have nothing to do at all with the difference between the actual aerodynamic terms TAS and IAS. That doesn't mean there is anything wrong with the code, it just mean's that it was very poorly named. It would've actually been better to have named them "VelocityWatermelon" and "VelocityTofu". At least there wouldn't be a false cognate problem for people looking at the code afterwards.

 

 

On 2/10/2025 at 4:03 AM, FTC_Rostic said:

To open .cs file use notepad++ or any text editor.

 

You have to make copy of .log file and rename it .csv like log_1.csv

After that excel or any other table processor all should open it.

Thanks, easy enough solution.

 

 

19 hours ago, BENKOE said:

It is very important to convert the geometric altitude (Z_AltitudeMSL), which is the actual virtual world 'tape measure metric' altitude above sea level, into geopotential altitude. The latter is a pressure altitude that is consistent with the assumption of a constant value of gravity (g=9.80665). Actually, it looks like Team Fusion Company is using 'tape measure metric' altitude as geopotential altitude.

You'll also need to know the air temperatures all the way up to your current altitude in order calculate this right? What is the difference between geopotential altitude and density altitude?

[343KKT_Kintaro]

In PC flight sims, we always called this a speed bar.

[BENKOE]

On 1/27/2025 at 10:42 PM, Volant_Eagle said:

... Is there a way to display an aircraft's exact in-game performance statistics on the HUD overlay? Things like true airspeed, indicated airspeed, climb rate, altitude, heading, etc? ....

 

Certainly, it's possible to display in-game performance using a 'HUD' or a 'speed bar'. This has been made possible by 1C-Maddox with the Full Mission Builder Scripting. So, how about moving this thread from <Technical Assistance> to <Single Player><Mission & Campaigns>?

That said, I’d appriciate to see this discussion continue. I’ve nearly finished my Single-Player mission on the topic, so just a little patience, please.

[Volant_Eagle]

On 2/12/2025 at 12:31 PM, BENKOE said:

Certainly, it's possible to display in-game performance using a 'HUD' or a 'speed bar'. This has been made possible by 1C-Maddox with the Full Mission Builder Scripting. So, how about moving this thread from <Technical Assistance> to <Single Player><Mission & Campaigns>?

That said, I’d appriciate to see this discussion continue. I’ve nearly finished my Single-Player mission on the topic, so just a little patience, please.

I suppose at this point this thread might be better for that section. Although the whole creating a specific single player mission that calculates everything out via script is not at all what I had in mind when I opened this thread. It seems like it's the only answer though and it does the job.

 

I was thinking this sim would have to have some sort of "speed bar" like @343KKT_Kintaro mentioned, and that I just couldn't find it. Unfortunately that doesn't seem to be the case. The scripting feature in CloD is truly awesome, and I don't know if other sims have anything like it, but it's not the same thing as a "HUD" or a "speed bar".

 

These missions you guys are making are great and will serve my purposes for the moment, but I'm still rather surprised there isn't anything even like the very simplistic speed bar from IL-2 1946. That feature in 1946 only displayed speed (not sure what kind), altitude, and heading. That's not really enough data for me, but it works the way I want it to work. You just pressed the keybind at any time, in any mission, whether single or multi player, and it toggles the data display on and off in the corner of the screen. The data was also live from the simulation, not recalculated and updated every half-second-ish.

 

Since that's apparently not a thing in CloD, I'll have to focus on what I can do which is use the script feature. I'm very interested in learning more about the script feature as well as anything and everything I can learn about the flight model. So I like where this thread has gone, and hope to continue the discussion, it just hasn't gone where I was originally thinking it would.

 

[BENKOE]

Thank you for the clarification and your interest. @Volant_Eagle, do you have the Desert Wings Map? It is better because we do not have virtual 'ISA' conditions in North Africa.

 

Edited on 05/03/2025:

Enclosed you find the first slightly more comprehensive Single Player Mission. I will expand / enhance it for further information in near future, ideally with all the necessary annotations . . . .

 

Performance_Data.zip

If you are not registered, you won't be able to download the file. Click here to sign in!

 

Edited June 19 by BENKOE
05/03/2025: first slightly more comprehensive Mission Update

[BENKOE]

During the Second World War (1939–1945), two primary methods of altitude measurement were used in aviation, based on the technological standards of the time:

(For nitpickers only)

Spoiler

 

Barometric Altimetry (Pressure Altitude)

• Technology: Barometric altimetry relied on an altimeter that compared ambient pressure to a standard pressure model of the atmosphere (standard atmosphere).
• The measured pressure altitude was calculated from the pressure using a standard atmosphere.
• Standard values (at sea level at the time):
• Pressure: 1013.25 hPa
• Temperature: 15°C
• Temperature gradient: −6.5°C/km
• Limitations: The displayed altitude was affected by deviations in pressure and temperature. It did not account for actual terrain elevation or gravitational anomalies.

 

Geometric Altitude (Above Ground or MSL)

• At close range, radar altimeters were used to measure height above the ground, where available (primarily in bombers or specialised aircraft).
• Radar altimeters were still under development during the Second World War but were experimentally employed in advanced aircraft (e.g., the German Heinkel He 177).
• Altitudes above Mean Sea Level (MSL):
• Altitude measurement above MSL was almost exclusively based on barometric measurements and assumptions about sea-level pressure.

 

Technological Limitations

• Geoid or Gravitational Models: Geodetic height systems as we know them today (e.g., WGS 84) were not available. Local maps and elevation models were used instead.
• GPS and Satellite Technology: These modern systems did not exist during the Second World War.

 

Conclusion:
During the Second World War, barometric altimetry was the standard method, as it was available in all aircraft and provided a sufficiently accurate determination of pressure altitude. Geometric altitude measurements were limited to specific scenarios, and precise geodetic methods like those used today were not yet feasible.

 

Edited Saturday at 08:37 AM by BENKOE

[343KKT_Kintaro]

In this very same forum, maybe two or three years ago, one player asked for a speedbar "alla '46" or "alla Great Battles" in Cliffs of Dover... but multiple discrepancies arose. I, who I'm mainly against speedbars, agreed with the idea that online servers could block the speedbar for everyone entering the server, so that this couldn't be and advantage for some and a disadvantage for others (those latter wanting to fly their aircraft in "full realism mode"). So, if it is an option, then why not. That was, and still is, my position.

[BENKOE]

On 2/11/2025 at 9:57 PM, Volant_Eagle said:

... ... < What is the difference between geopotential altitude and density altitude? > ... ...

 

I simply 'overlooked' the question, sorry.

The geopotential of a point is defined as the increase in potential energy per unit mass lifted from mean sea level to that point against the force of gravity [ref. 1]. It is a useful concept in meteorology, climatology, and oceanography; it also remains a historical convention in aeronautics as the altitude used for calibration of aircraft barometric altimeters [ref.2].

 

Only under the following conditions, geopotential altitude is equal to density altitude:

Temperature at mean sea level = 288.15 Kelvin = 15° Celsius
Ambient Air Pressure at mean sea level = 1013.25 Pascal = 760 mmHg
Ambient Air Density at mean sea level = 1.225 Kg/m³

 

ONLY at sea level, under the following conditions TAS = CAS = EAS:

Temperature at mean sea level = 288.15 Kelvin = 15° Celsius
Ambient Air Pressure at mean sea level = 1013.25 Pascal = 760 mmHg
Ambient Air Density at mean sea level = 1.225 Kg/m³

 

The properties are used as basis for engeneering and design of aircraft since nearly 100 years. It should be emphasized, that this properties propably will never match the actual/real/true atmosphere, and may only rarely approximate the average value at all altitudes simultaneously.

 

References:

[ 1 ] The ARDC Model Atmosphere, ARDC No.86, December 1956)

[ 2 ] Introduction to Flight, Anderson (2007), McGraw-Hill Science/Engineering/Math.

 

Edited June 29 by BENKOE

[Volant_Eagle]

Thanks very much for the reply @BENKOE. I've been away from the forums for awhile, but I certainly hadn't forgotten this thread or lost interest. It's been a combination of trips with work, getting knocked out of action for two weeks with a bad case of influenza, and lately having more interest in flying CloD than talking about it.

 

Still wrapping my head around this, but at first it seemed to me that Geopotential Altitude is more or less the same as Pressure Altitude. However, I read through pages 6 to 13 in your first source, and now I'm not so sure about that. Geopotential altitude is presented to be dependent on the reduction in the force of gravity with distance above sea level.  1 geopotential meter is the distance it would take to give a 1 kg mass 9.80665 joules of additional potential energy by lifting it. If the force of gravity was constant at all altitudes, then 1 geopotential meter would be the same as 1 geometric meter. But since gravity actually reduces the farther you get from earth, geopotential meters get 'stretched' longer and longer the farther you get from earth. So 10,000 geopotential meters will necessarily always be higher than 10,000 geometric meters. This is definitely not how pressure altitude functions.

 

This also seems to be at odds with what you said when you first mentioned geopotential altitude:

On 2/10/2025 at 7:47 PM, BENKOE said:

It is very important to convert the geometric altitude (Z_AltitudeMSL), which is the actual virtual world 'tape measure metric' altitude above sea level, into geopotential altitude. The latter is a pressure altitude that is consistent with the assumption of a constant value of gravity (g=9.80665).

 

I'm uneducated in this and I only quickly read a few pages from your source, so maybe I haven't gotten nearly as deep into this as I need to. But I'm still confused as to why we need to convert geometric to potential. It seems to me that geopotential altitude is only a tool used in a particular way of modeling the atmosphere, that is used in that model to help in determining what things like pressure altitude and other things should be at a given height.

 

Doesn't the atmosphere model in CloD already assume a certain pressure gradient and density gradient throughout the geometric altitudes? If it does, why not just use those values? And if those values don't necessarily match ISA, then who cares? The real atmosphere doesn't match it on any given day either.

 

 

Just curious, but are you still planning to post the C# method that on Feb 10 you said should be coming soon? Not that I speak a lick of C# yet, but it sounds like something that would be interesting to see.