Flight Investigation of NACA D(Sub S) Cowlings on the XP-42 Airplane IV : High-Inlet-Velocity Cowling Tested in Climb with and Without Propeller Cuffs and in High-Speed Level Flight Without Propeller Cuffs

Re s ults are p resented of fli g ht il easurements of the pe rf ormance and cooling c haracteristics of a short-nose high-inlet -velocity cowling on the XP-42 airplane for conditions of climb with and without propeller cuffs ~nd for high s pee d without cUffs.This cowling is one of a series be i ng tested at LMAL .The airplane speed was approximately 1 mile per hou r greater wit hout pr opeller cuffs than the previously measu red value with c Uff s.The p res su r e recovery on the front o f the engine avera ged 0.74 ai r plane impact pressure at high s peed withou t cuffR a s co mpared with 0.80 airplane i mpa ct pressure with cuff s. r ~ -4 TEST APPARATUS AND PROCEDUREThe i n stallatio n of the test equipment was described in reference 2 .Th e method used for making the cli mb coolin g tests was t he s ame as describ e d in ref erenc e s 3 and 4 .For t he cowli ng ~ith cuffs, full-power cli rr bs were made at indicated airspeeds of 155 and 140 miles per hou r in automa t ic rich a n d at 140 miles pe r hour in full ri ch.For the co ~li ng wit ho ut cuffs.the climbs were li mited to one at 15 5 miles per hour in a u to mat ic rich and one at 140 miles per hour in full ric h .The h i gh-sp e ed tests were conducted as described in reference 2 and g round coolin g tests, as described in reference 4. SYMBOLS bhp brake ho rse p o wer o density rati o ~ propulsive efficiency S wing area, squar e feet CD drag coefficient p observe d pressure above free-stream static pressure , i nch es of water q c a ir p 1 an e i mp a ct p re s sur e, inc h e ~ 0 f wa t e r RE SU 1'1' STh e data obtained durin g the h i g h-speed runs and du~ ing t e clim bo are p rese n te d in tables I and II.I n addition, the c hief cli mb-test da ta a r e s hown in fi g ures 2 and 3 in t h e for m of time hi stories of the cliobs.It will be noted that all te mpe rat u r e data for t he l 55-mile-per-hour climb with cuffs (fli gh t 1 6-1) are missin g .Anal y sis of the data from this .fli g ht indicated t hat cold-junction te mp erat u res had not stab ili zed and that temperatures were uncertain within a ran g e of about 15 0 F.