The single-spar, laminar flow wing of the H.P. 65 was considered a step too far due to limitations
on available construction techniques, so H.P. was asked to abandon that plan and switch to a simpler
design. This consisted of a new two-spar 55' span centre-section to which extended Halifax outer
wing panels were attached. The resultant Hercules 100 powered H.P.66 (Hastings B.Mk.I) was defined
by Spec. B.27/43, the specification was written around the design, two prototypes were ordered.
A third prototype was ordered as the H.P.69(Hastings B.Mk.II) with turbo-charged Hercules HE-15MT
engines, otherwise it was the same as the H.P.66. As a back up Merlin 25 engines in RAE 'idealized'
cylindrical cowlings, as used on Lincoln and Warwick, were also envisaged.
The H.P.66/69 wing design was used on the H.P.67 Hastings transport.
-info from Handley-Page Aircraft since 1907, C.H. Barnes, 2nd ed., Putnam 1987
So a Halifax III fuselage (with deepened bomb-doors) and extended outer wing panels, Hastings
style centre-section and Lincoln cowlings for a Merlin powered Hastings B.Mk.III.
:)