Differences between the -3 and -5 were numerous, but often not readily apparent. The Navy pressured Grumman to correct deficiencies in top speed and roll rate of the -3 when work began on the -5.
1. Top speed: The -3 Hellcat's top speed at its' rated altitude is usually given as around 375 mph TAS, while that of its' main competitor, the F4U-1, is around 400 mph.
2. Roll rate: While the -3 Hellcat's ailerons were considered an almost ideal control at speeds of around 100 knots, at speeds above 250 knots the roll rate slackened considerably. From a high rate near 65 degrees per second, the rate fell to around 35 degrees at speeds above 250 knots.
3. Weak horizontal stabilizers: In terminal velocity dives from high altitude the Hellcat's would often buckle by approximately 15 degrees out of line.
The fixes:
1. Top speed: A number of changes were made to improve top speed: A redesigned engine cowling reduced drag; a R2800-10W engine with water injection was installed; a high-gloss sea-blue paint job with factory applied coat of wax replaced the original three-hued paint scheme, further reducing drag. These changes made the -5 between 25 and 30 mph faster than the -3.
2. Roll rate: A spring-tab system was installed on the ailerons, reducing control forces and allowing full aileron deflection at speeds 100 knots higher than on the -3, in effect almost doubling the Hellcat's roll rate at high speeds.
3. Weak horizontal stabilizers: new stabilizers were designed with 10 inch wide, full-span 1/4 inch aluminum leading-edge cuffs to endure the buffeting during high-speed, high-g pullouts.
The -5 Hellcat in Aces High seems to me to have the improved roll rate but a top speed nearer that of the -3. I've never been able to get it above 380mph TAS.
Regards, Shuckins
