[2] A native of Alden, Iowa, Schalk started at West Point in 1944,[3] graduated in 1948,[1] then trained and received his pilot's wings at Nellis Air Force Base.

Schalk completed flight instructor school at Craig AFB[4] and taught at Laredo Air Force Base in Texas.

[1][5] He joined Lockheed in 1957, and in 1959 was chosen by Kelly Johnson as chief test pilot for the Skunk Works.

[5] As such, he assisted in the design of the cockpit of the A-12 as well as conducting the unofficial and official first flights of the aircraft and contributing to the resolution of initial instability issues.

[6][7][5] In his role as chief test pilot Schalk interfaced extensively and significantly with systems engineers for the A-12, YF-12, and SR-71, conducting the first thirteen flights of the A-12, the first four flights in excess of Mach 3.0, reaching a top speed of Mach 3.287, and conducting subsequent engineering test flights above Mach 3.0 as engine, inlet, afterburner and other critical systems were evaluated and fine-tuned, with altitudes in excess of 90,000 feet.