THE REACTION ON A WING WHOSE ANGLE OF INCIDENCE IS CHANGING RAPIDLY WIND TUNNEL EXPERIMENTS WITH A SHORT PERIOD RECORDING BALANCE

Summr;try.-A balance has been developed in the Aeronautics Laboratory at Canlbridge by which the reaction on a wing whose angle of incidence is increasing or decreasing rapidly can be recorded. The reactions have been measured on eight aerofoils, including those used in R. & M. 1588 2 • Large" hysteresis" effects at and above the stall have been found in two-dimensional conditions. I It is considered that these form a basis for accounting for certain full scale observations which have not hitherto been satisfactorily explained. It is proposed to extend the work to three-dimensional conditions. who took the records for two of the aerofoils. The balance was built in the Laboratory workshops by Mr. N. Surrey, to whose skill and workmanship a high tribute is due. Mr. Surrey also gave essential help in taking all the records. The work was inspired throughout by the advice and help of Professor B. Melvill Jones, to whonl the author vvishes to express his thanks.