FF 17-4-43 CRD RAE 21-4-43 eng calibration and efficiency trials. AAEE 5-43 wing drag and windscreen misting trials. RAE 4-44 compressibility trials and measurement of airframe drag up to Mach .89 in dives. A comb of 19 pitot heads install behind wing on fus and connected to ASI behind pilot During one dive on 27-4-44 S/Ldr A F Martindale (ETPS) reached a speed of 600ASI severely damaged the aircraft EN409 was replaced by PL827 HAL 6MU 4-1-45 8OTU 27-2-45 Ran out of fuel above cloud and bellylanded nr Quilty Co.Clare Eire 7-4-45