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).
Performance chart for A.CRV. cores with varying gaps.
| Identifier | ExFiles\Box 150\3\ scan0010 | |
| Date | 29th April 1936 guessed | |
| CHART # 3. 20 x 55 x 2 7/8 A.CRV. CORES .020 GAP .040 GAP .060 GAP B.T.U./MIN./SQ. FT. F.A./100° F.T.D. VEL FT/MIN. | ||