Do you guys think that this plane would have been an improvement over the F4 Wildcat? At first sight, I can only see more cannons, but I can be totally wrong here.
Check some important stats for both planes (from Wikipedia):
F4F-3 Performance:
* Maximum speed: 331 mph (531 km/h)
* Range: 845 mi (1,360 km)
* Service ceiling: 39,500 ft (12,000 m)
* Rate of climb: 2,303 ft/min (11.7 m/s)
XF5F Performance:
* Maximum speed: 383 mph at sea level (616 km/h)
* Range: 1,200 mi (1,930 km)
* Service ceiling: 33,000 ft (10,000 m)
* Rate of climb: 4,000 ft/min (1,220 m/min)
The real tactical weakness for the XF5F looks to have been service ceiling, which was unacceptably low for a plane of that era. But, at lower levels, the XF5F would have eaten the F4F-3's lunch in a B&Z fight - 50 mph faster, twice the rate of climb, plus the guns were concentrated in the nose, which would allow for better gunnery accuracy (less need for gun convergence). Compared to the A6M2, it would have had much better speed and better climb rate and about the same ceiling. Again, another likely winner in a mid- to low-level B&Z fight. Compared to the Bf110, it was slightly faster and had better climb, but wasn't as well armed and didn't have quite the range. Basically, it would have been a smaller, less heavily armed, shorter-ranged, ship-based equivalent of early versions of the P-38 Lightning.
In the game, it would be a fun ride. Good climb and speed, relatively maneuverable, and with a decent punch for an early war plane. Planned versions with a pair of 23mm cannon would be even more of a threat.
Historically, I think that the Navy ditched the idea of the twin-engined fighter due to limitations of the carriers at the time - limited space and relatively short deck - as well as budget, operational and maintenance considerations (a twin-engined plane requires twice the fuel/oil/lubricants of a single engined plane, and requires more maintenance). They might have also seen how twin-engined fighters fared during the Battle of Britain and assumed that all twin-engined heavy fighters were doomed.