[41Sqn_Banks]

Originally Posted by ACE-OF-ACES

Not likely..

They were more than capable of determining the airspeed that produced the best ROC. With regards to WWII they would do several test and different airspeeds to determine which one produces the best ROC.

One thing to take note of, with regards to WWII test data, most WWII fighter aircraft didn't have TAS gauges, which explains why most WWII ROC data gives airspeeds in IAS, and most if not all of those WWII test reports that do provide TAS, TAS was calculated (post test processing) from IAS.

So most WWII references are in terms of IAS. Where as today TAS gauges are more prevalent, and therefore most modern pilot discussions on Vx and Vy are talking in terms of TAS, where most make note of how Vx (TAS) and Vy (TAS) airspeed changes with altitude.

We also know that TAS changes with altitude relative to IAS, So even with a constant IAS, TAS is changing.

In WWII they typically referred to the airspeed that produced the best ROC as the 'best climb speed', which in todays pilot jargon equates to Vy (best rate of climb airspeed).

Therefore with regards to the WWII ROC test reports jargon vs modern pilot jargon, the constant indicated airspeed (IAS) in the WWII ROC test is the same as saying Vy indicated today, convert both to TAS and this WWII story will match those of today, where Vy changes with altitude.

+1