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).
Clarifying the definitions and testing of 'helix angle' and 'spiral angle' for a sequence starter.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan160 | |
| Date | 14th September 1926 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. By.{R.W. Bailey - Chief Engineer} By/RD. c. AJS. ORIGINAL EFC3/T14.9.26. v7650 RE SEQUENCE STARTER. There has been a little mutual confusion in the use and interpretation of the terms 'helix angle' and 'spiral angle'. It would appear to be generally satisfactory if these were definitely defined as in the diagrams. This will be consistent with your reference to the numerical values which you quote in your RL/M1.9.26 as the spiral angle, though in one place you have called this the helical angle. In the case of the 45° helix, which we have not yet tested, there is no ambiguity. In the other case, it is the helix angle which is 55° 8' and the spiral angle which is 34° 52', so that the one already tried is better than the one not tried, in accordance with the impression given during my visit. We shall be pleased to test this 45° spiral in place of the 34° 52' spiral if you think there is any advantage in this, but your note gives the impression that you wish us to test the 45° spiral as being a better proposition (smaller spiral angle) than the one already tested. As pointed out, this is not the case. We should also be pleased to know if, as we suppose, you are sending any further modifications which may in part supersede the instructions contained in your RL/M1.9.26. HELIX ANGLE SPIRAL ANGLE EFC. | ||