Don't make performances secret this time

[PE_Tihi]

Originally Posted by Rama

Actually these kind of data concern prototypes, or non-fully equiped aircrafts, that were often particulary well built and adjusted, with carefull and well done covering to get the best performances.

Data from production aircraft are IMHO more representative of combat aircraft.
Data for production aircraft can be retrieved from in-flight receipt test reports (when they were conducted, and when the test centers archives are available....). Normally in each production serie, some machines were intensivelly tested by the respective air forces in order to accept the production serie.
... but... even in these tests, you can find discrepancies in data recorded in test receipts for the same serie.

... I totally agree with your last sentence.

This is certainly a meaningful remark- prototype test perfomances tend to be higher then the production plane ones. But there is enough test data made on the production planes, too.
In any case, these differences are rather small. For my taste, speed differences of up to 10 km/h ( mind you, the game speeds are mostly accurate), or climb speed differences of 1 m/s would not make me bat an eyelid, nothing to say about writing a post.
Any task done in a too perfectionistic manner can last a lifetime