IAS vs TAS vs CAS

[hnbdgr]

Hi,

hope someone can answer this for me. Below is a chart from a 109 handbook(?) official name: Flugleistungkurven, BF 109 E Flugzeughandbuch, Berlin, 16 December 1939. It has 2 speed curves on the right. One begins at 450 kmh, the other one at 500 kmh

Qi3pUOW.jpg

I first thought that it's IAS/TAS but someone said it might be IAS/CAS - where the 450 curve is the calibrated air speed and the 500 curve is the indicated airspeed. Can anyone confirm? Isn't the discrepancy incredibly large?

What numbers were usually used in tests and official manuals? I have a limited understanding of this, but from what I read one uses IAS to calculate CAS and then adjusts for pressure to get TAS. So maybe it is TAS after all? But why is it lower then IAS on this chart? Instrument error? Were such large instrument errors common?

[Erpr.Gr.210_Mölders]

I do not want to be wrong but should be IAS ( Anzeige = Displayed ) and TAS ( wirklich = Real speed or TAS )

[Baffin]

I do not want to be wrong but should be IAS ( Anzeige = Displayed ) and TAS ( wirklich = Real speed or TAS )

This is certainly consistent since CAS is simply IAS corrected for installation error. I've never seen CAS this far apart from IAS. If it was, I'd hire a new instrument manufacturer.

[hnbdgr]

Right, my thoughts exactly. Was there something particular to the installation of the equipment on the emil that made IAS and CAS so different? The way I understand it, each aircraft has a particular IAS/CAS table. 109 F didn't have the same problem apparently, check the last page of this pdf:

http://www.kurfurst.org/Performance_...1F2_DB601N.PDF

So if the right curve is TAS, is TAS simply CAS adjusted for correct pressure?

[Barone]

CAS (or calibrated air speed) is simply an IAS that is corrected from issues due to the gauges (for example the position of the pitots on the fuselage).
CAS is not corrected from mistakes due to air density and pressure.
The one who got this kind of corrections is TAS or true air speed.

Inviato dal mio Moto G (4) utilizzando Tapatalk

[hnbdgr]

thanks, I thought that was what i was asking, anyway thank you for the answer