Mk3 corrosion resistance
The design of the Utility 101 was LED by Agusta but it was not an Agusta only product, the 101 was a true 50/50 design indeed Merlin Mk3 design leadership was WHL only, actually the proper designation of the aircraft should be Westland Merlin Mk3, compared to Lockheed Martin Merlin Mk1 (due to the Prime contracts placed).
The EH101 was designed from the start to be a multirole aircraft, Civil pax, Naval ASW and Utility variants being the big 3. A Mk3 is a UK specific utility aircraft, the Mk3A is a (now) UK modded Danish specific utility aircraft for comaprison.
The spec for Mk3 always stated that operation from RN ships was a requirement for the SH role and the aircraft was designed and built with that role in mind.
A folding capability for the Mk3 was costed for the MoD as an option prior to contract award but was not adopted on cost grounds. Fitting a folding system would not be difficult as all the bits would be 'off the shelf', albeit involving some MGB and head rework. A tail fold would be more involved but eminently do-able. (Actually do you need to fold the tail at all?)
The 'poor' payload capability of the design is caused in part to the inherent crashworthiness capability mandated in the design which is singularly absent in the Puma and Ch47 (which use 1960s rules). The strengthened floor was due to a RAF specific requirement to carry vehuicle inside the cabin which results in very high localised floor loadings, other users have not this requirement and the normal floor is a lot lighter. The floor also allows use of an integral hook (to react the loads into the structure) which was another unique RAF requirement as well. With hindsight it may have been a better bet for the RAF to have specified a role fittable hook and not lose a fuel tank, but I guess the Chinook influenec on having a 'hell hole' to see the load held sway. Other 101 utility users have gone that way.
Remember the USAF retired the C141 due to its lack of volume not its lack of payload, sometimes mass isn't everything.
Tallsar is correct in that MAYBE a twin engine variant would have been a better bet, however my guess is that a twin engined aircarft would have used a slimmer fuselage and that would have reduced the Merlin biggest asset of volume rather than true payload. A different engine to the RTM322 or CT7 would be needed however to cope with the engine out case.
Is triple redundancy 1980s thinking?, isnt the new CH53K a triple engined aircraft as well?
Anyway we are we are now and I cannot see new build Merlin aircraft for the RM being purchased however much those of us in the west country would love to see that happen!
DM