It is fair to say that President Trump’s visit to Britain has not been universally popular, but it did provide a bonus to what has already been a bumper week for aviation enthusiasts following the RAF Centenary flypast on Tuesday.
The Bell Boeing V-22 Osprey is to date the only tiltrotor aircraft ever to enter production. A tiltrotor is an aircraft with ‘proprotors’ mounted in rotating wingtip nacelles. For takeoff, landing, hovering, and low-speed horizontal flight, these are angled vertically and serve as rotors, allowing the aircraft to operate like a helicopter. As the aircraft changes to horizontal flight, they gradually swivel forward to serve as propellers, and the aircraft operates like a fixed-wing aeroplane. Tiltrotors and their close relatives tiltwings (where the whole wing swivels) are and old idea, going back to the 1930s, but none have previously made it past the prototype stage.
The Osprey combines the VTOL capability of a helicopter with the long-range, high-speed cruise performance of a turboprop aircraft. It first flew in 1989, but did not enter service until 2007. It is operated by the US Air Force, Navy, and Marine Corps. To date, the only non-American operator is the Self Defence Force of Japan.
The Osprey is therefore an uncommon sight in Britain, but when a US President visits, aircraft of Marine Helicopter Squadron One (HMX-1) are deployed to the US airbase at RAF Mildenhall. HMX-1 is the USMC helicopter squadron responsible for the transportation of the POTUS and other VIPS. They use the MV-22B version of the Osprey.
Between the 9th and 13th of July, a flight of three Ospreys was repeatedly seen in the skies over London. They appear for the most part to have been operating in a mode intermediate between full helicopter and fixed-wing aircraft.