Initially yes, if the two aircraft , Spit V and the Ta-152, it would seem obvious that the Spit is a faster aircraft AT 18'000 feet.
But at 27'000 ft, the Spit V takes 62 seconds from 175-275 mph, and the Ta-152 only took 37 seconds.
What do my tests show? At low level engagements, you have to be careful how you enage certain aircraft, and how you extend. If you're low and slow and want to extend in your P-51, if you have a La-5 or La-7 on your six, think again about your decision. Knowing top speeds and accleration rates help you better understand your aircraft and your fighting abilities.
There are also some aircraft performing well at ALL altitudes. The Bf 109G10, Spit XIV, F4U-4, and the Dora come to mind. It also shows the Tempest is not an ideal high altitude fighter.
It also shows that higher up, all aircraft perform different than those low down. It also shows there is a different class of planes to use for high altitude fighting. For example, you may want to avoid dog fighting a Bf 109 series higher up than down low unless you feel confident enough to defeat the pilot from the initial merge.
Use the data and try to understand the context it fits with respect to the aircraft you are engaging. Ie. You're in a Spit V at 18-20000 feet and are bounced by Bf 109's. You know that initially they out accelerate, out climb, and have a higher top speed. That has an impact in how you engage these aircraft understanding the disadvantages you may face.
That being said, it's the man, not the machine you have to worry about. But the man, flying his machine, understanding his strengths and weaknesses and those of his opponents makes him a much better fighter pilot.
