Hi Pappy,
>The Seafire III, which had folding wings and a four-bladed propellor, was about 7100 lbs loaded vs. the Spitfire Vc's loaded weight of a bout 6,800 lbs. However, the Mk.IX already has a four bladed-prop so I wonder how it would weigh as a Seafire.
I'm afraid I don't have any exact weight breakdown for this comparison. Maybe you could compare weights within one mark if a three-bladed propeller was tested against a four-bladed one? It could be that the Seafires had metal propeller blades, though - I seem to remember something about the fear of splinters if a Seafire was "pranged" on landing. A metal propeller probably would be heavier than a wooden one ...
By the way, from "Up in Harm's Way" by Mike Crosley, it seems like the extra weight of the Seafire was mostly concentrated around the aft fuselage, with the Merlin-engined Seafire being dangerously tail-heavy. The additional weight of the Griffon engine was most welcome and lent the aircraft much better deck landing characteristics.
(If you're into Spitfires, both of Crosley's book are worth a look - "They gave me a Seafire" about his wartime experience as a FAA pilot, and "Up in Harm's Way" about his post-war career as a test pilot.)
Regards,
Henning (HoHun)