RKK ENERGIYA’S KLIPER Original plans

For most of the 1990s the hard economic times forced RKK Energiya to limit manned spacecraft development to upgrading the existing Soyuz spacecraft. Work on a Soyuz successor didn’t resume in earnest until the turn of the century. By 2002 Energiya designers had settled on a lifting body borrowing technology from Soyuz and Buran. This was publicly announced as Kliper (“Clipper”) in February 2004 and described as a 12-14 ton spacecraft with a reusable return capsule. However, in November 2004 company officials revealed an alternative winged design for Kliper that was ultimately preferred over the lifting body.

In the 2004 plans Kliper had a reusable “Return Vehicle’’ (VA), made up of a crew cabin embedded in an unpressurized fuselage which could be either a lifting

body or a winged design. Attached to the aft of that was an expendable “Aggregate/ Habitation Compartment” (ABO), consisting of a Soyuz orbital module surrounded by a torus-shaped body. About half of the habitation compartment protruded from the aft of the body and had a docking port to link up with the ISS or other spacecraft.

The Return Vehicle’s blunt-shaped crew cabin offered 20 m3 of working space (five times as much as Soyuz) and could house a maximum crew of six (minimum crew of two). The independently developed fuselage would protect the front and lower part of the crew cabin during re-entry, descent, and touchdown. The fuselage and the upper part of the crew cabin had a heat shield consisting of 60 x 60 cm thermal covers made from the same material as Buran’s tiles. Also installed in the fuselage were LOX/ethanol attitude control thrusters and electricity-producing fuel cells derived from those developed for Buran.

The lifting-body configuration was probably inherited from so-called Recover­able Maneuverable Capsules (VMK) studied by Energiya in the early 1990s as return capsules for a series of vehicles intended for autonomous microgravity missions or space station servicing missions. The lifting-body fuselage was fitted with two rudders and two body flaps and would have a cross-range capability of up to 500 km (10 times more than Soyuz). Kliper would descend on parachutes, stowed in a container in the top section of the crew cabin, with pneumatic shock absorbers and small solid-fuel engines softening the touchdown.

For the winged version of the fuselage, RKK Energiya teamed up with the Sukhoy aviation design bureau, bypassing NPO Molniya, its former partner in the Buran program. The winged Kliper would make a classical horizontal runway landing using a conventional landing gear. This design would increase cross-range capability to 1,200 km and lower the deceleration forces for the crew during re-entry. Moreover, in the absence of parachutes, shock absorbers, and soft-landing engines, all of which are expendable systems, the degree of reusability would be higher.

The ABO’s Habitation Compartment performed the same functions as the Soyuz orbital module, providing 8 m3 of extra living space for the crew. Mounted on the aft end would be an active Soyuz-TM type docking port and a series of LOX/ethanol attitude control thrusters and maneuvering engines. The torus-shaped body sur­rounding the Habitation Compartment would among other things carry a thermal control radiator and propellant tanks for the aft engines and thrusters. The ABO would be jettisoned from the rest of Kliper after the deorbit burn and burn up on re-entry.

The launch vehicle originally considered for Kliper was Onega, a much upgraded Soyuz rocket with an increased propellant load and different engines that had evolved from two earlier proposals called Yamal and Avrora. Next, RKK Energiya set its sights on the already existing Zenit rocket, but the political problems stemming from the use of a Ukrainian launch vehicle eventually led Energiya back to upgraded Soyuz rockets, with Khrunichev’s Angara-A3 seen as a possible alternative. In the original Onega configuration Kliper had a launch escape tower mounted on its nose section, but in the later configurations this was replaced by eight solid-fuel rocket motors installed on an adapter between the launch vehicle and the spacecraft. As in

the earlier Zenit/OK-M and Energiya-M/OK-M2 plans, these motors could be used either in abort scenarios or to augment thrust in a nominal launch [16].