Block Russia 1998 "USSR 50k Supersonic Tupolev TU-144, OVERPRINTED TU-144LL 1968-1998" Mint** (TU144LL-98SBN)

The "Tupolev Tu-144LL" Flying Laboratory Project (1996-1999)

1987 marked the end of Tupolev Tu-144 flights with Aeroflot, and on February 27, 1990, the Tupolev Tu-144D made its final flight as a commercial airliner.

That same year, Tupolev contacted NASA and offered to use a Tupolev Tu-144 as a testbed for the High Speed ​​Commercial Research program, whose goal was to design a second-generation supersonic airliner. In 1995, Tupolev Tu-144D serial number 77114 (assembled in 1981 but with only 82 hours and 40 minutes of flight time) was brought out of storage. Significant modifications, costing $350 million, were carried out, including re-engining. The old engines were replaced with those from the Tu-160 bomber.

This new 'militarized' version was designated Tu-144LL, 'LL' standing for Letayuschaya Laboratoriya (Flying Laboratory). The project comprised six phases of flight testing and two ground tests. The Tupolev Tu-144LL made its first test flight on November 29, 1996. The program planned for 32 test flights, but only 27 were completed, and the project ended on April 14, 1999, with the final flight of the Tupolev Tu-144LL (No. 77114).