Third, the 109 has better power to weight ratio, 1 horsepower carries 4,167 pounds, while in the spit16 each horsepower carries 4,264 pounds. Not as much difference, but the spit gains advantage even though it should perform a bit worse. This is from the spits larger wings and more lift.
Fourth, they have the same amount of power, and the spit16 is much slower. That means the spit-airframe is way more draggy than the 109 airframe.
Both of these assumptions are false.
(1) Power-to-weight ratio means very little. At a glance, it can be an indicator of relative climb performance, but ultimately what drives climb rate is excess power available. If the Spit climbs faster than the 109K-4, then it means that the Spit has greater excess power, regardless of power loading or wing loading.
(2) The Spit and 109 both had almost the same Coefficient of Drag. The difference is that the Spit has almost 70 ft^2 of wing area more than the 109. I'd argue that the Spit probably had a "sleeker" fuselage than the 109K-4, but that extra wing area is what slows the Spitfire down, not a higher Cd. There were some other aspects of the Spit wing that decreased top speed performance (washout), but its not necessarily all about the drag, unless we do the math, and determine that. It could also be a thrust issue. Its possible for one aircraft, making the same amount of power, to create much more thrust than another aircraft with the same power.
