# Thread: TAS Calculation | Forums

1. I've developed a TAS calculator but I need to know how the game handles temp in general and temp as related to altitude specifically (since TAS is a function of Density Altitude ambient temp factors in). I'm assuming that the game is designed around the standard day with Pressure Altitude at sea level a constant 29.92 in Mg and sea level temp a constant 15C/59F. However temp would change with altitude. In RL this is non-linear so how does the game model this.

If my assumptions about the standard day are incorrect and/or someone knows how the game models temp, I would appreciate it.

2. Thats a great question, one that I don't have an answer to.

I've developed a TAS calculator but I need to know how the game handles temp in general and temp as related to altitude specifically (since TAS is a function of Density Altitude ambient temp factors in). I'm assuming that the game is designed around the standard day with Pressure Altitude at sea level a constant 29.92 in Mg and sea level temp a constant 15C/59F. However temp would change with altitude. In RL this is non-linear so how does the game model this.

If my assumptions about the standard day are incorrect and/or someone knows how the game models temp, I would appreciate it.
Only one map is said to be close to the STD, that is the Crima map. How close, not sure, Oleg just that it is the closest

4. It's 2% for every 1000 ft. so your TAS is 2% higher than your IAS for every 1000 ft. of altitude. At 20,000 ft. there is a 40% difference.

5. Crimea map with time of day set to 12:00 is exactly standard conditions, they set it up that way for comparison testing with RL figures. They chose Crimea because it has the climate closest to standard conditions. Other maps and other times of day have different "sea level" temperatures, especially the winter maps.
You can do some map calibrating by comparing the speedbar (red numbers in the bottom left of scree, IAS) to the No Cockpit speed indicator (TAS). Bear in mind that the speedbar rounds down to the nearest interval (10km/h when in metric mode, don't recall if it's 5 or 10 mph/knots) so if it's showing 270km/h then

270km/h <= IAS < 280km/h

Doing this No Cockpit comparison you'll see that in many of the winter maps IAS is greater than TAS at sea level and up to a couple of hundred metres altitude in some cases.

6. It's 2% for every 1000 ft. so your TAS is 2% higher than your IAS for every 1000 ft. of altitude. At 20,000 ft. there is a 40% difference.
The 2% change only accounts for the density gradient from the decrease in air mass as you move up through the atmosphere and assumes that temp is constant as you increase altitude.

Crimea map with time of day set to 12:00 is exactly standard conditions, they set it up that way for comparison testing with RL figures. They chose Crimea because it has the climate closest to standard conditions. Other maps and other times of day have different "sea level" temperatures, especially the winter maps.
So the map makers set the sea level temp, what about the gradient at altitude from winds aloft, inversions, etc. Are these modeled into the game? Maybe I should post this in Oleg's forum?

7. Originally posted by Tully__:
Crimea map with time of day set to 12:00 is exactly standard conditions, they set it up that way for comparison testing with RL figures. They chose Crimea because it has the climate closest to standard conditions. Other maps and other times of day have different "sea level" temperatures, especially the winter maps.
Hey Tully! Up to now I was under the impression that the Crimea map was the CLOSEST to 'std', but reading your post I sounds like your saying it is actully spot on? Is that true?

Originally posted by Tully__:
You can do some map calibrating by comparing the speedbar (red numbers in the bottom left of scree, IAS) to the No Cockpit speed indicator (TAS). Bear in mind that the speedbar rounds down to the nearest interval (10km/h when in metric mode, don't recall if it's 5 or 10 mph/knots) so if it's showing 270km/h then

270km/h <= IAS < 280km/h
10mph I belive

Originally posted by Tully__:
Doing this No Cockpit comparison you'll see that in many of the winter maps IAS is greater than TAS at sea level and up to a couple of hundred metres altitude in some cases.
This is why I asked you the first question above.. In that I see that same error between IAS and TAS at sea level even on the Crima map at high noon! I have never been able to explane that, in that if Crima is truly 'std' than they should be the same! But I have seen a 20mph difference between the two in more than one test.

8. I wonder if sensor and positional errors are modeled plane per plane as history.
They are known for some planes but I think not all we have.
In that case we should do IAS to CAS correction before CAS to TAS conversion.
This would be something that gets more error with increasing speed somewhere above
200-240 mph (320-400 kph).

My speedbar shows kph but with an ini change could be showing mph. Round down to
10's of kph is inherently less than round down to mph as 10 kph is about 6 mph.

9. Originally posted by WWMaxGunz:
I wonder if sensor and positional errors are modeled plane per plane as history. They are known for some planes but I think not all we have.
highly unlikely! In that Oleg has never even hinted at that, and it is hard enough to find standard data on these pleans, trying to find the CAS correction for 200 planes would be a big task, and not worth it IMHO in that 99.9% of the users would never notice it! Thus not worth wasting PC cycles on let alone modling time let alone research time.

Originally posted by WWMaxGunz:
In that case we should do IAS to CAS correction before CAS to TAS conversion. This would be something that gets more error with increasing speed somewhere above 200-240 mph (320-400 kph).
If, but as noted, highly unlikely for several good reason.

Originally posted by WWMaxGunz:
My speedbar shows kph but with an ini change could be showing mph.
the speed bar can be toggled within the game from kph, to knt, to mph. As for an ini change, never heard of that option to set it to one or the other.

Originally posted by WWMaxGunz:
Round down to 10's of kph is inherently less than round down to mph as 10 kph is about 6 mph.
Problem is the errors I have seen are in the 20mph+ range.