The classic NASA program for computing zero lift wave drag of an arbitrary airplane configuration has been adapted to run on the PC. The source code (public domain) is included in this collection of aeronautical software.

The concept known as the area rule is one of the great success stories of airplane design. The area rule says very simply that the transonic wave drag of an aircraft is essentially the same as the wave drag of an equivalent body of revolution having the same cross-sectional area distribution as the aircraft. This fact, coupled with the knowledge of the shape that minimizes drag shows designers how to reshape the fuselage and other components of an airplane to reduce the drag of the total configuration.

Since the rule was formulated, and verified experimentally, attempts have been made to estimate aircraft wave drag by a theoretical analysis of the equivalent-body area distributions. It has been found that reasonably good wave drag estimates can be made near a Mach Number of 1 if the slender-body-theory is applied to the aircraft area distribution. Numerous theoretical and experimental investigations have shown that the fuselage and other components of an airplane can be reshaped in a way that will reduce the wave drag of the total configuration. A typical configuration will frequently have a fuselage with a local minimum of area near the middle of its length, sometimes referred to as "coke-bottling".

The transonic area rule was considered so valuable that attempts were quickly made to extend the results to higher Mach numbers. This theoretical effort culminated in the development of the so-called Supersonic Area Rule, which is more complicated than the transonic rule.

This procedure can be extended to higher Mach numbers with good accuracy by using the supersonic area rule to determine the equivalent-body area distributions. The area distribution for the transonic area rule can be developed with drafting techniques. The supersonic area rule depends on computing areas intercepted by oblique cuts through a configurations and requires a considerable amount of computational geometry.

- Go to the page of references for the Supersonic Area Rule program.
- Go to the download page to download the Area Rule program and sample cases.