1. Limited Fuel Capacity: The SR-71's fuel capacity was approximately 80,000 pounds (36,000 kilograms) of JP-7, a specialized high-energy fuel. At its top speed of Mach 3.2, the aircraft's fuel consumption rate was extremely high, burning through its fuel rapidly.
2. Fuel-to-Airframe Ratio: The SR-71 had a relatively low fuel-to-airframe ratio, meaning that a large portion of its weight was dedicated to structural components and systems rather than fuel. This limited its endurance at top speed.
3. Heat Management: The SR-71's skin temperatures could reach extremely high levels due to aerodynamic friction at supersonic speeds. Maintaining structural integrity and preventing overheating required the aircraft's constant cooling systems to work efficiently. Prolonged operation at top speed could put strain on these systems.
Considering these factors, the SR-71's maximum endurance at top speed was approximately 1 hour and 20 minutes, or roughly 2,200 miles (3,500 kilometers). However, it's important to note that such high-speed, fuel-intensive missions were rarely conducted, and the SR-71 usually operated at subsonic or supersonic speeds to conserve fuel and increase its range.
