Ts-1 (LL-1, -2, -3)
flying laboratory

    In September 1945 the LII-MAP (Flight Research Institute) asked Tsybin to investigate wings suitable for flight at high Mach numbers (if possible, up to 1). In 1946 numerous models were tested at CAHI (TsAGI), as a result of which OKB-256 constructed the Ts-1, also called LL-1 (flying laboratory 1). Almost in parallel, a design team at the OKB led by A V Beresnev developed a new fuselage and tail and two new wings, one swept back and the other swept forward. The LL-1 made 30 flights beginning in mid-1947 with NII-VVS pilot M Ivanov, and continuing with Amet-Khan Sultan, S N Anokhin and N S Rybko. On each flight the aircraft was towed by a Tu-2. Casting off at 5-7km (16,400-23,000ft), the aircraft was dived at 45°-60° until at full speed it was levelled out and the rocket fired. In winter 1947-48 the second Ts-1 was fitted with the swept-forward wing to become the LL-3. This made over 100 flights, during which a speed of l,200km/h (746mph) and Mach 0.97 were reached, without aeroelastic problems and yielding much information. The sweptback wing was retrofitted to the first aircraft to create the LL-2, but this was never flown. The original Ts-1 (LL-1) was essentially allwood.
   The original wing had two Delta (resinbonded ply) spars, a symmetric section of 5 per cent thickness, 0° dihedral and +2° incidence. It had conventional ailerons and plain flaps (presumably worked by bottled gas pressure). Take-offs were made from a twowheel jettisonable dolly, plus a small tailwheel. In the rear fuselage was a PRD-1500 solid-propellant rocket developed by 11 Kartukov, giving 1,500kg (3,307 Ib) (more at high altitude) for eight to ten seconds. Flight controls were manual, with mass balances. On early flights no less than one tonne (2,2051b) of water was carried as ballast, simulating instrumentation to be installed later. This was jettisoned before landing, when the aircraft (now a glider) was much more manoeuvrable. Landings were made on a skid. Various kinds of instrumentation were carried, and at times at least one wing was tufted and photographed. The LL-3 was fitted with a metal wing with a forward sweep of 30° (according to drawings this was measured on the leading edge), with no less than 12° dihedral. The new tailplane had a leading-edge sweepback of 40°. To adjust the changed centres of lift and of gravity new water tanks were fitted in the nose and tail. Both LL-1 and LL-3 were considered excellent value for money.

References and Credits:

1. «It is unified in three wings» / I.Galeev. Wings of the homeland /
2. History of airplanes designs in the USSR (1938-50), v.2 / V.B.Shavrov /
3. «Encyclopedia Astronautica» M.Wade
4. Russian Aviation FAQ
5. Soviet X-planes / Ye.Gordon, B.Gunston, 2000/