Difference between airspeed indicator and airspeed shown on HUD

[FeuerFliegen]

I've always noticed a substantial difference between the airspeed indicators and the airspeed listed in the HUD.

 

Right now I'm in the Albatros D.Va, the airspeed indicator reads 166kph, and the HUD reads 138.  I'm currently at 3760m altitude, but I see a difference at all altitudes.

 

Is this a realism thing as the airspeed indicators back then weren't accurate?  or a game bug?

[1PL-Husar-1Esk]

Look what speed show speed gage on the albatross wing. This true airspeed . TAS vs IAS you are looking at.

[FeuerFliegen]

3 minutes ago, 1PL-Husar-1Esk said:

Look what speed show speed gage on the albatross wing. This true airspeed . TAS vs IAS you are looking at.

 

but HUD doesn't show TAS, right?  and if the HUD was TAS, it would be higher than IAS at high altitude, not substantially lower, right?

 

 

Also, at 3000m, the HUD shows 145kph.  The in game notes state that at 3km alt, max IAS is 145.  The plane's wing speedometer is bouncing around between 167-170kph.

 

 

It's almost as if the airspeed indicator is showing TAS, and HUD is IAS, which couldn't be realistic with that technology as there's a bigger difference the higher my altitude goes.

[1PL-Husar-1Esk]

The wing speedometer is TAS but it might be less accurate as higher plane goes. 

[FeuerFliegen]

8 minutes ago, 1PL-Husar-1Esk said:

The wing speedometer is TAS but it might be less accurate as higher plane goes. 

 

a WW1 plane having a TAS indicator is historically accurate?

 

 

The only WW2 planes with TAS indicators are the jets.

[1PL-Husar-1Esk]

29 minutes ago, SCG_FeuerFliegen said:

 

a WW1 plane having a TAS indicator is historically accurate?

 

 

The only WW2 planes with TAS indicators are the jets.

Not all WW1 indicators are TAS but those german device mounted on  the wing are. 

[J2_Trupobaw]

German wing ananometers measure TAS. WW1 planes with actual in-cockpit clockface gauge usually use IAS (Breguet was different for some reason). If in doubt, look for Pitot tube somewhere on the wing :). HUD displays IAS.

[BMA_Hellbender]

Indeed those anemometers have negligible wind resistance and hence show (very close to) TAS rather than IAS. I reckon IAS is the more useful airspeed to measure at all altitudes in a WWI fighter plane.

[No.23_Gaylion]

On 11/14/2022 at 6:38 AM, SCG_FeuerFliegen said:

 

a WW1 plane having a TAS indicator is historically accurate?

 

 

The only WW2 planes with TAS indicators are the jets.

 

A man learns it wasn't as archaic as he thought...

[LukeFF]

On 11/14/2022 at 3:38 AM, SCG_FeuerFliegen said:

a WW1 plane having a TAS indicator is historically accurate?

 

 

The only WW2 planes with TAS indicators are the jets.

 

A 1933 discussion about anemometers on German WWI planes:

 

http://aerade.cranfield.ac.uk/ara/1933/naca-report-420.pdf