Have you ever heard that strange whistle, “fweep” or “whoop” sound an F-15 makes before takeoff? Most people assume it’s coming directly from the engines, but the real explanation is far more interesting. In this video, I explain what causes the famous F-15 noise, how the aircraft’s variable exhaust nozzles work, and why you hear that distinctive sound during taxi, lineup and pre-takeoff power changes. Filmed at RAF Lakenheath, home of the USAF F-15E Strike Eagle.

Source: Why Does The F – 15 Make THIS Strange Noise Before Takeoff?