Transonic

The Whitcomb area rule, also called the transonic area rule, is a design technique used to reduce an aircraft 's drag at transonic and supersonic speeds, particularly between Mach 0.75 and 1.2.

This is one of the most important operating speed ranges for commercial and military fixed-wing aircraft today, with transonic acceleration being considered an important performance metric for combat aircraft and necessarily dependent upon transonic drag.

Boeing is developing the Transonic Truss-Braced Wing configuration through the Sustainable Flight National Partnership, a NASA initiative to make aviation more environmentally friendly.

But this equation is not valid for transonic flows where the Area rule applies.

Euler–Tricomi equation The Euler–Tricomi equation is used in the investigation of transonic flow.

Finally, the Me 262 wing had only a slight sweep, incorporated for trim ( center of gravity ) reasons and likely would have suffered structural failure due to divergence at high transonic speeds.

In a transonic turbine the gas flow becomes supersonic as it exits the nozzle guide vanes, although the downstream velocities normally become subsonic.

The European transonic wind tunnel uses this technique.

Top speeds for fighters rose steadily throughout World War II as more powerful piston engines were developed, and was approaching transonic flight speeds where the efficiency of propellers drops off, making further speed increases nearly impossible.

Transonic and supersonic flows are compressible, and neglecting the changes in density in these flow fields will yield inaccurate results when performing calculations.

With its 8m test section and airspeed up to Mach 1 it is the largest transonic wind tunnel facility in the world.