SR-71 Blackbird

The SR-71 Blackbird is the fastest air-breathing jet aircraft on the planet, able to reach speeds approaching Mach III (three times the speed of sound) and flying at incredibly high altitude. It appeared in Hellsing: Volume 5, as well as the OVA Hellsing: Ultimate IV.

In Hellsing Ultimate
Alucard used a SR-71 Blackbird that Integra Hellsing borrowed from Imperial War Museum Duxford (a real life plane with AF serial number 61-7962) as a means to get him aboard the Eagle, an aircraft carrier that had been hijacked by Rip Van Winkle and several Millennium soldiers. The plane itself, though of American origin, was extensively modified by the RAF after they acquired it. Stripped of virtually all of it's sensory equipment and reduced to a single-seated aircraft, the RAF's SR-71's modifications were intended specifically to turn the former spy plane into an aircraft designed to, as one RAF officer put it, "rewrite speed records." Due to its speed and high-flying capabilities, Alucard was able to approach the Eagle at a height far outside the range of any antiaircraft ordinance that the vessel possessed. After positioning the aircraft directly above the ship, Alucard sent it into a nosedive, intending to ram straight into the Eagle.

During its descent, the SR-71 took several hits from the Eagle's anti-air defenses once it finally got into range, including Rip van Winkle's magic bullets. However, Alucard used his powers to hold the plane together long enough for it to crash into the deck of the ship. The impact set both the deck and the SR-71 itself alight, and killed many of the Millennium soldiers. Miraculously, the SR-71 somehow managed to remain structurally intact instead of disintegrating upon impact with the Eagle. The former's shape and vertical orientation, coupled with the fact that the nose had buried itself in the Eagle's flightdeck, made it appear as a fiery cross.

Due to the damage it had suffered, Alucard was unable to use the SR-71 to return to England, effectively trapping him on the Eagle - instead, he then used his powers to slowly pilot the ship back to London. During the trip, the charred remains of the SR-71 remained sticking out of the deck like a cross. When Alucard unleashed his full power, the SR-71 fell apart to expose the vampire's coffin within its fuselage.

Real World Facts
The SR-71 Blackbird reconnaissance vehicle is a high flying spy plane that was built by Lockheed Martin and took its first flight in 1964. It was retired by NASA in 1999. The Blackbird is still the fastest plane with air-breathing engines that has ever flown and served an important role in history as a spy plane.

Trivia

 * One of the SR-71's tail fins has an image of a cartoon bat with a cute smile, as well as the words "We are on a mission from God."