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).
The American aircraft industry concerning developments in two-row radial engines, ground boost, and the use of magnesium.
| Identifier | ExFiles\Box 179\3\ img142 | |
| Date | 1st March 1932 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} Hgr. c. E.{Mr Elliott - Chief Engineer} Rg.{Mr Rowledge} c. LD. RV. c. Pl. LT. SP.{Mr Spinney} 2 copies to a.m. ORIGINAL Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/ADL.4.32. AIRCRAFT INDUSTRY U.S.A. MARCH 1932 x2064. AIR COOLED RADIALS. Two Row Radials. Both Curtiss Wright and Pratt & Whitney are developing the 14 cyl. two row radial in two sizes 600 BHP. and 800 BHP. The 600 BHP. Wright has an overall diameter of 45", is 1510 cu.ins. displacement, rated at 2200 R.P.M. and is 6 : 1 C/R.{Sir Henry Royce} It is ground boosted to 4" of Hg. and gives 150 B.M.E.P. The 800 BHP. Pratt & Whitney is alleged to weigh only between 900 and 1000 lbs. We saw the latter installed in a machine alleged to do 210 M.P.H. without any "cleaning up". It was merely being used as a flying test bed. The engine certainly looks remarkably compact. They have various deflectors to distribute the air round the rear cylinders and the usual range of cowlings. Thermo couple tests show that on these double row radials the rear cylinders run no hotter than the front cylinders which seems difficult to believe. They set a limiting figure of 450° - 470°F.{Mr Friese} at the rear sparking plug boss. These double row radials have run 50 hours tests successfully. Ground Boost Engines. Engines are now being supplied with 4" Hg. ground boost to run on the highest Octane fuel (87). They have been type tested at an M.E.P. of 150 lbs/sq.in. The temperature rise across the blower for this boost was given to me as 20°C. which seems unduly high. Use of Magnesium. Magnesium is being used in standard production by Pratt & Whitney for the rear portion of the crankcase carrying the auxiliaries and drives. This piece is a casting, the alloy being given as 4 - 6% Al. .5% Mn. They specify a minimum tensile for it of 28,000 lbs. The castings certainly look a nice job, very little thicker main section than aluminium but with more generous radii and bosses. | ||