I am planning on doing several analyses into airpower subjects in the near future. I have no problem finding information on the majority of aircraft, engines and weapons systems from the Third Generation of Fighter Aircraft (1960's onward), this includes other types of aircraft. However finding information on aircraft between 1945 and 1960 can sometimes be very difficult. Indeed finding information on aircraft from 1903 to 1945 can prove problematic. Some aircraft are very well documented while others, particularly those aircraft that served on the losing side, are documented poorly and information is difficult to find.
Particularly I am trying to find technical information on propellers (propeller efficiency charts); I am looking to do a project on the development of aircraft propulsion partly because I can tie the findings into projects that look at particular aircraft and generations etc. In the future I may need information on weapons systems (radars etc.) that were present on aircraft 1945-1960.
A lot of the information is difficult to find and may indeed be impossible to come by, being destroyed. I am aware a lot of the information on Rotol propellers was destroyed in a flood, very annoying. In other cases information is destroyed because it is deemed useless by either the company or hands it has fallen into; the allies did a major burning exercise solely because of the cost of transporting all those paper records. Other information was lost during mergers etc. Lastly information I sometimes come accross seems pointless, they kept all the company minutes and random informational crap and threw away all the technical information