IL2 IAS TAS Formula - not real life! - Printable Version
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+---- Thread: IL2 IAS TAS Formula - not real life! (/showthread.php?tid=60306)
IL2 IAS TAS Formula - not real life! - tityus - 28.03.2009
As similar questions have started debates that degraded into flame wars, I plan to be careful and concise with my post. Since this is, if I'm not wrong, still an unanswered question, I'm gonna try again and see if someone has an answer for it.
Does anyone know the formula used by IL-2 to calculate TAS from IAS? (not real life)
I'm aware that we have some spreadsheets, good software such as bombsighttable2, reference tables, rules of thumb... I also know what a E6B is and that TAS is affected by many other variables such as air density, temperature, moisture and etc... bear in mind that I'm not looking for a good method or solution to calculate my TAS in the game.
We could also take educated guesses on how the programmers, to compensate the lack of moisture and temperature modeling, could have linked a variance to one of the other factors to alter the ADAF - Air Density Adjustment Factor, so it loses the linear characteristics the absent variables confer to it. However, before we do that, let's not loose the original question:
Does anyone know the formula used by IL-2 to calculate TAS from IAS? once again, not real life, guys.
Maybe we get lucky this time and find someone who knows that formula.
t
- PB0_Mighty-8 - 28.03.2009
Hi !
Interesting question that made me ask another question :
why do you think IL2 don't use "real life" IAS/TAS rules ?
I my humble opinion, il2 might use a standard atmosphere chart (may be of his own ?) to calculate TAS/IAS.
I don't think this chart include moisture ratio.
It seems that many map have their own temperature (i.e. desert map are warmer than northern countries's maps) If my memorie's still not too bad.
At least one airplane in the game is fitted with a fonctioning external temperature indicator.
This is how a friend o'mine discovered that ground temperature where different between two maps so.... this temperature is probably used in IL2.
I don't know if this temperature decrease if the aircraft climb in the skies.
May be might you ask this question to Oleg's team on 1Cmaddox's forum ?
Regards
M8
- Loon - 28.03.2009
Yes, the temperature decrease the higher you climb. It's modelled in the game.
- Lt.Wolf - 28.03.2009
I am not sure of the formula but I have made a spreadsheet that works this out for you using basic things from real life not including air temperature and i find that it is very accurate and something my self and a few other modders and FM guys use.
(The link is inoperative)
Tell me what you think, does it help? It works for the game not real life so much, enter a value say IAS KMH then convert it to TAS, then switch in game to TAS and see what the results are.
- tityus - 28.03.2009
Apparently I've fail to convey my message.
The formula used by IL-2 to calculate TAS from IAS (not real life) is the goal.
I know people are just trying to help, but I'm afraid if the thread gets buried with out of focus discussions it may prevent someone that actually knows the answer to contributing.
I'm not against debating, that would be the next step after not getting an answer from someone with the knowledge. I hope I don't sound indelicate, hateful or ungrateful, but I still have a hard time in fora where a thread gathers five or six pages without an answer.
I hope PB0_Mighty-8, Loon and Lt.Wolf don't get offended by this follow up, I understand you guys cared enough to respond and where fast on your replies, I believe with no other intent than to help. Thank you, really. I'll be sending you guys a PM.
But, right now, what I'd like to know is the formula used by IL-2 to calculate TAS from IAS (not real life).
t
- zulu64 - 28.03.2009
The temp and lapse rate used in IL2 are close but do not exactly match standard lapse rates in real life. The same goes for for density reduction versus altitude.
- Bluebottle - 14.06.2009
I'm also looking for the same info.
ROSS_YOUSS made IL2Compare and the data is in TAS, and allegedly this data was an output of the in-game polynomial. However, there is no update since 4.071m and so we have no definitive reference for performance of any of the new aircraft.
This is a problem for map makers, as players argue over performance of the new aircraft. Fw190A3 vs the Ic Fw190A4 is a good example.
Utilities such as LesniHU autopilot and UdpGraph permit speed tests to be carried out offline. I've been doing that under the following conditions: Crimea, 25%, rads closed, overheat off, unlimited fuel.
UdpGraph has two functions for the TAS calculation; TAS() takes arguments of IAS, altimeter, MSL pressure, MSL temp, and as Crimea is supposedly 745mmHG and 25 deg C, should be ideal. The other TAS function, TAS2(), takes arguments of IAS and altimeter only and outputs TAS assuming a standard atmosphere. Problem is, if you plug standard atmosphere arguments (763, 15) into TAS() it doenst give the same result as TAS2(), when it should. So it doesnt look like UdpGraph TAS() function is using the correct formula/polynomial. It's close, but exact would be nice.
There have been a few discussions over the years about the 'TAS formula' or 'polynomial' that is written into the game. The last poster confirmed that the atmosphere in game is 'non standard'. Now that the game has been opened up, it really should be possible for someone to post what the actual TAS formula/polynomial is, which takes the MSL pressure, and MSL temp arguments, so that direct comparisons can be made with IL2Compare data. Just post something we can paste into Excel. Please!
:?:
- tityus - 14.06.2009
Bluebottle,
Since I had no answer in many fora that I asked (either it wasn't a concern for those with the knowledge or no one knows it), I decided to work on the equations from scratch.
As I fly full switch, the more refined eq was desired for precision high level drops. Currently I'm not able to access my material, but by the end of this month, I'll get back home, where I have my "non-work-related stuff" and I'll provide you with the one I come up with. Although it wasn't extracted from the game code, I believe it's precise enough for you to use with UdpGraph and you tests.
Would that help?
t
- Bluebottle - 15.06.2009
Thank you yes I'd be interested to see it