From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Wind tunnel test results for a 3 1/2 Litre Bentley, detailing model configurations and performance data.
| Identifier | ExFiles\Box 160\2\ scan0169 | |
| Date | 13th February 1934 guessed | |
| WIND TUNNEL TESTS. 3 1/2 LITRE BENTLEY FIGURES FOR MODELS IN TUNNEL | TEST | FRONT WINGS | REAR WINGS | SCREEN | RADIATOR | TAILS | BODIES | STEPS | FLAT PLATE TUNNEL DRAG IN LBS | CORRECT. DRAG BY REFLEXION METHOD | REFLEXION TUNNEL DRAG | THEORETICAL DRAG ON CAR AT 86.0 M.P.H. IN LBS | PROJECTED AREA IN SQ. FT. | K FROM THEORETICAL TUNNEL DRAG | REMARKS | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 25 | NIL | NIL | 35° | VERT. | LONG | MODEL 3 | No | 1.006 | | | 208.0 | 18.135 | 0.0165 | | | 26 | CYCLE TYPE | NIL | 35° | VERT. | LONG | MODEL 3 | No | 1.118 | | | 232.1 | 19.025 | 0.01845 | | | 27 | CYCLE TYPE | CYCLE TYPE (A.E.) | 35° | VERT. | LONG | MODEL 3 | No | 1.170 | | | 243.0 | 19.025 | 0.01725 | | | 28 | CYCLE TYPE | FARED TO BODY CYCLE TYPE | 35° | VERT. | LONG | MODEL 3 | No | 1.120 | | | 232.5 | 19.025 | 0.01845 | | | 29 | CYCLE TYPE | FARED TO BODY CYCLE TYPE | 35° | SLOPING | LONG | MODEL 3 | No | 1.117 | | | 232.0 | 19.025 | 0.01845 | WITH UNDERSHEET. | | 30 | CYCLE TYPE | FARED TO BODY | 35° | VERT. | LONG | MODEL 3 | No | 1.032 | | | 212.0 | 19.025 | 0.01815 | WITH UNDERSHEET. | | 31 | NIL | NIL | 35° | VERT. | LONG | MODEL 3 | No | .917 | | | 190.0 | 18.135 | 0.0144 | UNDERSHEET. | | 32 | SLIPPER | NIL | 35° | VERT. | LONG | MODEL 3 | No | 1.226 | | | 255.0 | 20.000 | 0.01725 | | POSSIBLE CAR PERFORMANCES | DRAG AT 95 M.P.H IN LBS (COMPUTED) | K BASED ON B.23.A.E. SEE APPENDIX | 1/2 MILE SPEEDS | LAP SPEEDS | MAX. ROAD SPEED | REMARKS | |---|---|---|---|---|---| | 287.0 | 0.0189 | 103.5 | 98.5 | 108.0 | PROPORTIONALLY DERIVED FROM THE | | 320.0 | 0.01885 | 100.0 | 95.0 | 105.0 | FACT THAT THE STREAMLINE SALOON B.23.A.E. | | 335.0 | 0.01972 | 98.6 | 93.6 | 103.6 | (CORRES. TO TEST No 28) WITH 92.5HP AT THE | | 321.0 | 0.0189 | 100.0 | 95.0 | 105.0 | ROAD WHEELS AT 4150 R.P.M. LAPS BROOKLANDS | | 320.0 | 0.01885 | 100.0 | 95.0 | 105.0 | AT 95 M.P.H. & DOES THE FLYING 1/2 MILE AT 100 M.P.H. | | 293.0 | 0.01725 | 103.0 | 98.0 | 108.0 | WITH MAX. ROAD SPEED OF 105 M.P.H. AXLE RATIO 3.73 TO 1. | | 262.0 | 0.0154 | 104.8 | 101.8 | 109.8 | MAX. ROAD SPEED = 1/2 MILE SPEED + 5 | | 352.0 | 0.0207 | 97.1 | 92.1 | 102.1 | 1/2 MILE SPEED = LAP SPEED + 5. | COMPARISONS OF THREE TESTING METHODS. | TEST | FRONT WINGS | REAR WINGS | SCREEN | RADIATOR | TAIL | BODY | STEPS | TUNNEL DRAG | METHOD OF TESTING | REMARKS | % VARIATION | |---|---|---|---|---|---|---|---|---|---|---|---| | 1 | STD. WITH OUTSIDE VALANCE | STD. | 17° | VERT. | SHORT | STD. SALOON | Yes | 1.121 | MODEL SUSPENDED IN SPACE. FLAT PLATE | | 80% | | 2 | STD. WITH OUTSIDE VALANCE | STD. | 17° | VERT. | SHORT | STD. SALOON | Yes | 1.230 | AS GROUND REFLEXION | SAME AS TEST 4 | 88% | | 3 | STD. WITH OUTSIDE VALANCE | STD. | 17° | VERT. | SHORT | STD. SALOON | Yes | 1.400 | METHOD. | TEST 24. | 100% | e STREAMLINE SALOON - B.23. A.E. | ||