Tsybin LL-1, LL-2 and LL-3 experimental gliders with solid engines

[Stargazer]

In 1946-1948, Pavel Tsybin developed three flying laboratories (летающих лаборатории or "LL") with different wings, all using solid propellant.

All three variants were designed with the same airframe, but with three different wings of the same area (10.0 m²):

• a straight wing version (LL-1),
• a forward-swept wing version, with a 30 ° angle (LL-3)
• a swept-wing version, with a 30° angle (LL-2).

Only the first two aircraft were built. They both used a Kartukov RPD-1500 II solid rocket motor design:

• The LL-1 glider (Ts-1, or experimental glider No.1) was a straight-wing aircraft of all-wood construction. It featured a monocoque plywood fuselage. The wing had a +2° dihedral and a 3° leading edge sweep.
• The LL-3 glider (experimental glider No. 3) had the same size, area and mass as LL-1, but its wings were swept and it was made of duralumin (wood being considered too risky).

Over the 1947-1948 period, these gliders produced more than 100 test flights in the hands of test pilots C. Amet-Khan, S. N. Anokhin and N. S. Rebko). These aircraft flew at target speed and represented great experimental material. In a typical flight sequence, the glider, loaded with ballast water, was towed to a certain height. It was then unhooked, the engine was run and the glider reached its top speed. It then went down, the pilot came out of the dive, ballast was poured, and the glider landed empty. The glider wings were attached to the fuselage on a dynamic suspension, which allowed to determine the pressure on the wing and tail at the approach to the critical Mach number. Specific loads on the wing changed twice during the flight with ballast water.

All work on the aircraft and gliders with solid fuel in that period was not purely empirical. Engineers with some practical experience and recognition in the field of solid propellant motors took part in these experiments. Still, the main drawback of solid motors was that they did not allow to increase the speed of the aircraft for a long time. That is why experiments on the application of liquid rocket engines for aircraft were carried on.

 

[Stargazer]

Another set of profiles from Ognenneye Krelya (1930-1946):

 

[igor-mich]

From the Russian magazine "Wings of Motherland"

 

[Stargazer]

A better quality version of my first photo: