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).
Calculations for pressure correction under the bonnet based on car speed and air velocity.
| Identifier | ExFiles\Box 87\1\ scan0172 | |
| Date | 6th November 1935 | |
| (Appendix - Sheet 2) Hs{Lord Ernest Hives - Chair}/Std.14/KW.6.11.35. Correction for pressure under bonnet :- For car speed of 85 m.p.h. equiv. dynamic head = .070 x 124.7 x 27.7 / 64.4 x 144 = 3.250 "H2O ∴ Total head in front of matrix = 3.250 + Pa{Mr Paterson} where Pa{Mr Paterson} = atmos. pressure. From sheet 5, air vel. at exit from matrix = 35 ft/sec. ∴ equiv. dynamic head = .070 x 35² x 27.7 / 64.4 x 144 = .26 "H2O App. (See Sheet 7) From tests on car (also see/sheet6) total head under bonnet = Pa{Mr Paterson} + .67"H2O ∴ Difference of total head 3.250 - .670 (under running conditions) = 2.580 "H2O Difference of total head under rig conditions = 3.250 - .260 = 2.990 "H2O. | ||