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).
On Pratt & Whitney's progress with single and double-row radial engines, comparing them to Wright's.
| Identifier | ExFiles\Box 173\1\ img164 | |
| Date | 22th January 1933 | |
| Hs{Lord Ernest Hives - Chair} from Rm{William Robotham - Chief Engineer} I S G W O R R G E B Y L R / -F / Rm{William Robotham - Chief Engineer} 3 / K W L P F 29 34 Pratt & Whitneys General Progress Pratt & Witneys are keeping about parallel with Wrights with their single & double row radials. They all seem to be about 1.35 lbs / H.P. and have not quite reached 1/2 B.H.P. per Cu. Inch. They are not in trouble with exhaust valves at the moment, they can get 160 M.E.P. with 8c.c. T.E.L / gal without breaking down on the 180hr. type test previously commented on. I asked them what they had actually achieved by the double row radials which have now got to the state of the first production order of twenty five. The reply was that, compared with a single row radial of the same size & H.P. they had picked up 6-8 M.P.H. in top speed, they were slightly worse off on power weight ratio but not worse off on consumption per B.H.P. The fact that the double row | ||