JTO,
At the risk of stating the blindingly obvious, putting an aircraft on board ship always involves a weight penalty to whatever a 'realistic' payload is. The RN Commando Helicopter Force is having to manage a fairly significant programme to fit the Merlin with not only a folding tail, but a folding head as well as a modified main landing gear that can actually withstand deck landings. I'd offer the thought that not having these fitted to the aircraft in the first place wasn't exactly 'realistic' from a 'Joint' point of view. Of course, anyone's free to disagree with that thought. On board ship, according to a recent brief from the CHF guys, now that it folds, you can get 4 Merlins into the hangar space occupied by one (non-folding) Chinook. remember, space is always scarce on a carrier, no matter how big it seems.
Best regards as ever to the good folk at CHF getting the Mk4s and their crews and their maintainers up to full 'jungly' standard..
Engines