Its four Pratt & Whitney JT9D-7R4W or Rolls-Royce RB211-524C2 turbofan engines gave it the 747SP a cruising speed of Mach 0.88, but it could fly as fast as Mach 0.92 with 46,500 pounds of force.

Long after the end of World War I and World War II, Rolls-Royce's RB211 line of engines burst onto the scene in the early 1970s. With 42,000 lbs of thrust behind it, the original made a name for ...