это разгон не в пикировании, а по прямой
В описании к этой картинке написано:

"....Acceleration
The ability to accelerate quickly is of paramount importance to fighters and the interceptor class has an obvious advantage in this respect. For comparative purposes it is impracticable to take into account maximum speed as acceleration is only operationally useful at the slower speeds when an interception suddenly has to be made from slow cruising.

For instance, the Tempest V, which is faster than the Spitfire XIV, takes less time to reach any given speed, but the Spitfire has the best acceleration, followed by the Mustang III, Tempest V, Thunderbolt and Meteor III. The unhappy position of the Meteor is accounted for by the natural sluggishness of early jets at the lower speeds. Here again, the power to weight ratio coupled with clean lines in design has considerable effect.

First prize to the Spitfire XIV...."

по пикированию там тоже есть каринка: http://www.wwiiaircraftperformance.org/wade-dive.jpg

Короче весь отчет:
http://www.wwiiaircraftperformance.org/sl-wade.html