Photographer: JT Heineck

Image Source: https://images.nasa.gov/details/ACD21-0016-003_F4_P4_4-15_12Hprint

These patterns are shock and expansion waves created by the jet aircraft flying at Mach 1.02. Shockwaves, depicted in black, are small regions of sudden state change caused by aircraft features which disturb the flow [1]. Expansion waves, depicted in the yellow regions, are regions of flow acceleration generated by the aircraft directing airflow around its exterior [2]. These waves change air density throughout the flow field enabling refractive visualization techniques.

The photographer, JT Heineck, utilizes background oriented schlieren to visualize the complex shock and expansion patterns formed in flight. While schlieren imaging has traditionally been limited to imaging test flows within wind tunnels, NASA’s technique enables schlieren imaging of full-size aircraft in flight. By tracking vegetation on the desert floor, the photographer assesses how light refracts off the supersonic flow field surrounding the passing jet aircraft [3].

Using this visualization technique, the true nature of supersonic flight is revealed; There is an elegance to flow field. The waves curl and mingle around the two crafts. The powerful streaks in the shocks are complimented by the delicate structures in the expansions. These aircraft, unseen to our eyes normally, manipulate the air into beautiful patterns whilst maintaining a balance of flight, control, and speed. The best engineering creates solutions which elegantly balance multiple competing factors; this photograph highlights that balance by illuminating this hidden flow.

[1] https://www.grc.nasa.gov/www/k-12/airplane/oblique.html

[2] https://www.grc.nasa.gov/www/k-12/airplane/expans.html

[3] https://arc.aiaa.org/doi/epdf/10.2514/1.J059495