Bf109 - Measurement of Air Speed (Fahrt)

[Varrattu]

Dec-21-2024


Hello all,

enclosed you will find a small single player mission (Tobruk / Desert Wings) to play around with indicated airspeed vs. True airspeed. All lovingly packaged for Christmas in a single ZIP file. Unpack it into your < \Documents\1C SoftClub\il-2 sturmovik cliffs of dover\missions\Single\ > folder ...

As soon as you started in a Bf109F-2 at around 5200m above the Mediterranean Sea a 'HUD' will show you for example


264.81 K 5200 H,m 963.5 QNH kmH: 592.8:444.3 – 444.2 kmhIAS


where

264.81 K..................... = ambient air temperature in Kelvin
5200 H,m.................... = geopotential altitude AMSL
963.5 QNH.................. = "Nautical Height" pressure at sea level
kmH: 592.8................ = true airspeed obtained from game
444.3 – xxx.x kmhIAS = indicated airspeed obtained from game
xxx.x. – 444.2 kmhIAS = indicated airspeed the player has chosen

You can simulate an airspeed indicator calibrated for a sea level temperature between 15° and 40° Celsius. Therefore you press mission menue TAB-4-.

Have fun and

Merry Christmas and Happy New Year

Varrattu

[Varrattu]

Important Information für Mission Builders and Virtual Pilots:

It is vital for accurate navigation that Mission Builders have an estimate of the ground speed that will be achieved during each leg of a flight. The Full Mission Builder (FMB) provides the following function for this purpose:

double resultant = AiAircraft.getParameter(part.ParameterTypes.Z_Velo city TAS, -1);

Where subtype <-1> returns the resultant as current Ground Speed in metres per second.

The impact of wind speed on ground speed is obvious but wind direction is equally important. There are two situations to be considered:

• The wind direction changes (either with altitude or with the position)

• The wind direction remains the same but the aircraft heading changes. As a result, the crosswind and headwind/tailwind component also change, impacting the groundspeed.

If you want to get the True Airspeed, I strongly recommend using the following function:

double resultant = AiAircraft.getParameter(part.ParameterTypes.Z_Velo city IAS, -1)

Where subtype <-1> returns the resultant as current True Airspeed in metres per second [m/s].