Stealth aircraft Earlier stealth aircraft (such as the F-117 and B-2) lack afterburners, because the hot exhaust would increase their infrared footprint, and flying faster than the speed of sound would produce an obvious sonic boom, as well as surface heating of the aircraft skin which also increases the infrared footprint. As a result, their performance in air combat maneuvering required in a dogfight would never match that of a dedicated fighter aircraft. This was unimportant in the case of these two aircraft since both were designed to be bombers. More recent design techniques allow for stealthy designs such as the F-22
Undercompressive shock wave Undercompressive shock wave An undercompressive shock wave is a shock wave that does not fulfill the Peter Lax conditions. Ordinary shock waves are stable, that is the speeds of characteristic behind the shock are greater than that of the shock itself, which is greater than the characteristics in front of the shock. The characteristic speed is the speed of small, travelling perturbations. These conditions are necessary for a shock wave to remain and not decay. If the peak of a wave moves faster than at its base, then the wave front becomes self-sharpening and eventually becomes a nearly discontinuous shock,