Above 20000 ft - the Spit should be better. Between 10 and 20 kft - it's everyone's guess. Under 10 kft - Yak-3 should be very much competitive.
Spit that uses 150 grade fuel and trying to force combat in vertical might skew combat in it's favor very much.
What is this?Just a basic comparison.
The Yak-3 entered VVS service in June 1944. Haste in production caused weight
to rise and standards of finish to fall which would cut speeds as much as 20 mph.
By November 1944 over 800 Yak-3s had been produced but they had to be with-
drawn from operational service because the finish was pealing off do to substandard
resin which did not protect the wood sufficiently from moisture and cold. Most
of these aircraft had been repaired and placed back in service by January 1945.
The Yak-3 was an extremely dynamic aircraft at low and medium altitudes. Its roll
rate was fairly close to Fw-190A (per Erik Pilawskii). German pilots reported the Yak-3
could turn tightly and climb vertically for an unnaturally long time (at a steep angle).
Soviet pilot comments: Control forces remained light and crisp at the highest
airspeeds, and control harmony was exemplary.
I posted all the above because there are a lot of publications out there that give
substantial information on the Spitfire but not all that many that are that informative
about the Yak series of aircraft.
Yak-3 early (Spitfire L.F.IX A/C No.BS 543 @+18 boost)
Altitude / Speed / Climb
Meters / MPH / FPM
SL........352 / 4135 (336 / 4620)
1,000..367 / 4280 (350 / 4653)
2,000..379 / 3740 (365 / 4695)
3,000..382 / 3650 (380 / 4302)
4,000..398 / 3345 (384 / 3922)
5,000..400 / 2795 (383 / 3860)
6,000..384 / 2255 (398 / 3608)
7,000..374 / 1705 (407 / 2934)
This shows that the standard Yak-3, when functioning properly, was faster up
to roughly 5,500m (when functioning properly). The late Yak-3 (1945) was very
reliable, not so much in mid-1944
150 mph: ~96 (82) deg./sec.
200 mph: ~137 (105) deg./sec.
250 mph: ~160 (93) deg./sec
400 mph: ~74 (41) deg./sec.
The Yak-3 could out roll the Spitfire, but not by all that much. The figures
given above are for the Fw-190A and are probably actually better than the
1,000m: 17L/19R (18.5) seconds to complete 360 degrees.
4,000m: 20.0 (18.5) seconds to complete 360 degrees.
The Yak was clearly more maneuverable at low altitudes. However, It is also
clear that around 5,500m the Spitfire began to dominate. The thinner air
at higher altitudes required a higher lift wing in order to compete.
Armament: 1 x 20/120 rds.+2 x 12.7/150rds. (2 x 20/120rpg. +4 x.303/350 rpg.)
By May 1944 the Spitfire L.F, Mk. IX was being utilized at +25lb. boost with
150 octane fuel and sea level speeds had risen to the 354-358 mph territory.
That would be Part 2 of this story.
Combat Ceiling: 28,080 (37,000) ft.
Wing Loading: 36.26 (29.37) lb./sq. ft.
Power Loading: 5.795 (4.134) lb./hp.
Combat Weight: 5,795 (7,110) lb.