Work on the two projects is inseparable.
14 July 1939: W1 orders as an exact duplicate of the experimental engine.
24 August 1939: Instructions issued to re-design the experimental engine exactly as W1. New type of ball-bearing changed completely the turbine end of the engine. Design of combusion chambers changed to a completely fabricated design. Much drawing and experimental welding as a result of Power Jet's insistence of 1/64" sheet metal. Satisfactory technique developed only 21 Feb. 1940. Design of vapouriser system and fuel jets changed; final details of these not yet received from Power Jets.
8 Sept. 1939: Changeover of WI to suit A[eronautical] I[nspection] D[irectorate] inspection giving rise to much unexpected extra work.
Change in design of blade fixing in the turbine disc and a spare wheel ordered: a great deal of layout work to fit it to the experimental engine. Blower casing design changed twice owing to apparently minor changes in shape of air outlet pipes. Changeover from Hoffmann t Ransome and Marles ball bearings entailing extensive changes to all drawings of the turbine end of the rotor and new drawings of bearing housing details. Final particulars only received from Power Jets on 16 Feb. 1940.
Problems with having to make three sets of drawings of the governor, partly because when the second set were completed, after 29 days' work, Power Jets desired to use a static governor instead.
Details of work on the gear case and auxiliaries, the fuel pump (re-drawn three times) and the tachometer (final decision not yet received).
Analysis of man power: 95 man-weeks on the W1 and 76½ man-weeks on the experimental engine, wind tunnel, wheel vibration, shaft heat test, tender drawings, etc.
Details of drawings.
As to the W2: if a definite settled design is available it should be possible to produce working drawings in 56 man-weeks = 8 calendar weeks. So far all that has been done is the ordering of the main forgings. They heard from Power Jets on 23 Jan. 1940 that no work should be done until the final layouts were received, which they were at 4 p.m. on 22 Feb. 1940.