Challenges of building the SR-71 Blackbird using Titanium

The SR-71 Blackbird's innovative design mandated the use of titanium, a metal previously unutilized in aircraft construction, due to its exceptional strength at high temperatures. However, the U.S. faced a shortage of readily available titanium, prompting the government and Lockheed to create dummy corporations in Europe to source titanium, including from the Soviet Union. The machining of titanium posed significant challenges as standard tools would be damaged by this hard metal; hence, specialized titanium tools were developed for its manufacturing. The material properties of titanium became critical, with traditional aluminum losing strength beyond 300 degrees Fahrenheit, making titanium essential for the aircraft's operational speeds. The thermal expansion of materials at such high speeds required unique design adaptations, resulting in the need for panels that fit loosely on the ground to allow for expansion during flight—consequently leading to panel gaps. Moreover, the aircraft's skin doubled as its fuel tank to minimize weight, which caused fuel leakage when stationary due to these gaps. To address this safety concern, a custom, non-flammable fuel was developed, allowing operations near the leaking fuel without immediate ignition risks.