Mh. I have some concerns if the report should be taken as a basis for FM development.

It clearly says that the authors of the report have some doubts about their finding as it does not entirely fit with reports from pilots.

The very first page says that both the Hurricane and the Spit were reported to be heavy on ailerons at high speeds while the Hurricane was measured to make the bank of 90° in 2 secs while the Spit's roll rate was measured to 8sec. It is obviously a discrepancy between pilots' complaints about the heaviness of BOTH aircraft and the measurements made on two individual aircraft with one being considerably lighter than the other.

The authors encouraged to contact Fighter Command in order to find out if the Hurricane used for measurement was too light or the used Spit too heavy.

I think this report is not a good base for any FM modelling and more consolidated data is needed.

For me 8sec at very high speeds for fabric cover ailerons is - in the first instance - as good as any other value because I simply do not know what would be a realistic number. My guess is that it is anyhow difficult to tell. And more difficult to extrapolate from other types - even from those who also have fabric covered ailerons. There are too many factors entering into the equation to make a definitive statement on roll rate just by knowing the cover material. I think that the aileron distortions which are the cause for modified aileron sensitivity at high speed not only may worsen with fabric cover but also with sub optimal supporting structure. Rolling also means to modify air streams over the wing assymetrically and wing aerodynamic form may impact how effective ailerons are.

Another matter is how much force the pilot can exercise upon the ailerons. Or vice versa how strong the aileron forces are that the pilot has to counter.