CHDB A-90 Orlyonok (Eaglet) (Ekranoplan) Ground Effect Flying Boat (2024)

The Soviet Navy made use of several "ekranoplan" design forms during the Cold War decades, these pseudo-aircraft designs utilizing ground effect running to skim of fly over the surface of the water. Neither true aircraft nor true watercraft, the types were of value to Soviet warplanners for their hauling capabilities and inherent fuel efficiency when compared to traditional aircraft while lacking the drag encountered by the hull of watercraft. In the late 1960s. In the late 1960s and early 1970s, work was undertaken on a new ekranoplan vehicle, the Central Hyrdofoil Design Bureau's A-90 "Orlyonok" ("Eaglet") with its design attributed to engineer Rostislav Evgenievich Alexeev.

The craft was developed with transport capabilities in mind as the Soviet Cold War Army placed a premium on being able to move mass quantities of man and machine to wherever they were needed across the vast Soviet frontier and elsewhere. Such ground effect aircraft fit the bill and were often developed in complete secrecy from the prying eyes of the West - many of their capabilities remaining a mystery until the fall of the Soviet Empire in the early 1990s. One unique feature of the A090 design was its wheeled undercarriage which could be deployed during amphibious assaults - much to the surprise of defenders would be the A-90 continuing its running from water to dry land while carrying its troop complement or Armored Personnel Carrier (APC) further inland!

Only five of the type were eventually constructed with the first being reserved for static testing. The first flyable prototype became "S-23" and it completed a first flight in 1972 from the surface of the Volga River. It was then relocated to the waters of the Caspian for further work until it suffered a crash in 1975. It was reborn as the "S-21" in 1978 but then it, too, was lost to a crash later in 1992. "S-25" appeared in 1979 while "S-26" followed in 1980. The series achieved formal service introduction in 1979 with the last units - S-25 and S-26 - not retired until their usefulness had run out in 1993.

As completed, the A-90 featured the requisite boat-like hull mated to a conventional aircraft-type fuselage featuring monoplane wings and a T-style tail unit. The cockpit was fitted over the nose for a commanding view of the action ahead and an internal loading ramp was built into the lower nose section for loading/unloading cargo. The nose assembly was hinged to open sideways and allow the needed access to the hold. The wing mainplanes were low-mounted at midships onto the fuselage sides. There was armament carried but only intended for local defense, this in the form of 2 x 12.7mm heavy machine guns fitted to a dorsal turret along the fuselage spine just aft of the cockpit.

Engines were buried within the sides of the frontal fuselage and consisted of 2 x Kuznetsov NK-8-4K turbofans outputting 23,155lb of thrust each. These secondary installations were angled with their intakes cut into the upper nose section and their exhaust ports emanating from the lower fuselage sides. At the top of the vertical tail fin was a single Kuznetsov NK-12MK turboprop engine delivering the primary 34,171lb of drive power through a four-blade contra-rotating propeller arrangement for cruising. Performance from the arrangement included a cruising speed of 250 miles per hour with an operational range out to 935 miles and a service ceiling of 9,850 feet. The turbofan engines were used during take-off actions for the necessary lift and landing was aided by a retractable ski system under the belly.

The typical operating crew became six personnel with the hold able to accommodate up to 150 combat-ready infantry or similar load (including armored vehicles, supplies, medical litters, or fuel). Payload tolerances peaked at approximately 61,730lb. The airframe featured an overall length of 190.6 feet with a wingspan of 103.3 feet, and a height of 53.4 feet. Maximum Take-Off Weight (MTOW) was 308,650lb.

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