No problem At the moment your map still doesnt seem to be showing As to information from Kew a fully loaded two terabyte hard drive would about cover it Of course it goes without saying that your own work takes absolute priority If you have time and only if have a read of httpwwwwwiiaircraftperformanceorg and httpwwwspitfireperformancecomspitvrsehtml  there are some interesting documents citedin the meantime enjoy your research and dont get blocked again Cheers