A collection of internal reports recording handling trials, autopilot and other navigational equipment, night flying, gust research, the development of air mail operations and other technical assessments of various rotorcraft and other aircraft types.
Aircraft examined include the Agusta Bell 47, Bristol 171, Bristol 173, Bristol 192, de Havilland DH.106, Fairey Rotodyne, Sikorsky S-51, Westland-Sikorsky S.55 / Westminster and their variants.
Reports were issued by the Helicopter Experimental Unit, Research and Long Term Development Branch & Research and Special Development Department. Report authors include N. E. Rowe, R. H. Whitby, G. S. Hislop, R. N. Liptrot, R.A.C. Brie and P. A. Hearne.