Vertical Take-Off and Landing (VTOL) flight of fixed-wing fighter aircraft eluded aeronautical engineers for decades until several of the many initiatives of the 1960s ultimately yielded viable forms. The most famous of these became the British "Harrier" which was produced in two distinct marks - a land-based attack form and the "Sea Harrier" navalized form, the latter seeing combat service during the Falkland War of 1982. For the Soviet Union, the concept only ever truly materialized in the Yakovlev Yak-38 "Forger" which served the Soviet Navy from 1976 to 1991. 231 of the type were produced but these aircraft were limited in their ordnance-carrying capabilities and overall performance - as such not an outright success. Other programs, such as the Yak-36 "Freehand" of 1963 (the program yielding four prototypes), helped to further the Soviet goal of VTOL fighter flight.
In 1975, Yakovlev OKB was directly given the task of broadening the capabilities of its Yak-36 design with a formal government contract. The product was envisioned to become a fleet defense fighter for the Soviet Navy with inherent supersonic capabilities to keep pace with fighters of the West. This meant that the aircraft would have to display fighter-like qualities such as agility, sound weapons integration, and performance for the ranged interception role needed against incoming aerial threats. The new VTOL fighter program was born under the "Product 48" name and came to be known by the Soviet Navy as "Yak-41".
Design studies began to weed out incompatible engine arrangements and configurations. The chief challenge lay in providing supersonic performance while maintaining a vectored thrust capability and this led engineers to adopt a single-engine layout for both safety and simplicity. The thrust vectoring would come from a nozzle set at amidships in the fuselage (aided by smaller "thrust jets" installed at the forward section of the airframe) and general forward thrust/lifting through a jetpipe at the rear of the aircraft. The rear jetpipe was designed to turn down to 90 degrees to further support the VTOL action at the rear of the aircraft - an arrangement now seen in the American Lockheed F-35 "Lightning II" 5th Generation strike fighter.
With this single engine layout in mind, engineers developed the airframe to include twin tailbooms straddling either side of the engine installation. The remainder of the aircraft mimicked the design lines seen in previous Soviet high-speed aircraft of the period - namely the Mikoyan-Gurevich MiG-25 "Foxbat" and MiG-31 "Foxhound" with their slab-sided forward fuselages, large and rectangular intake openings (located to either side of the cockpit), and small-area wings clipped at their ends and showcasing sweep along their leading edges. The wing mainplanes were designed with a folding feature to aid in carrier storage and the reinforced wheeled tricycle undercarriage was retractable. Titanium was used to protect those surfaces expected to be exposed to the extreme temperatures of the list units while general areas were completed with composites where possible. The Yak-41 design ultimately utilized a three-engine layout. Its primary forward thrusting/lift unit was a Soyuz R-79V-300 turbofan engine outputting 24,300lbf on dry thrust and 34,170lbf with afterburner engaged. The lift engines comprised 2 x RKBM RD-41 turbojets delivering 9,300lbf of thrust apiece.
As a combat aircraft, the production-quality Yak-41 (Yak-41M) was slated to carry a 30mm GSh-301 series internal cannon as standard for close-in work, the cannon was fed by a 120-round cassette. Five hardpoints were integrated (four underwing, one fuselage centerline) for the carrying of various Soviet air-to-air missiles - up to 5,735lb of external stores in multiple combinations to suit short-, medium-, and long-ranged targets.
Yakovlev OKB was cleared to constructed four total prototypes during development and this lead to four aircraft designations in sequential order: 48-0, 48-1, 48-2, and 48-3. 48-0 was reserved as a static testbed and 48-1 trialed the engines so it was left to 48-2 to complete the series' first flight on March 9th, 1987 when the aircraft completed a conventional take-off and landing. The first hovering attempt was successfully completed on December 29th, 1989 with prototype 48-3 followed by the first compound action (vertical take-off with forward flight) recorded on June 13th, 1990. The first vertical carrier-based landing took place on September 26th, 1991.
In practice, the Yak-41 exhibited strong qualities and pilots reported a responsive aircraft with excellent fighter-like performance. Indeed, the prototypes claimed several aviation records though, due to the top secret development of the design, the "Yak-141" designation was submitted to the record books instead. Once this designation became known to the West, NATO assigned the design the codename of "Freestyle". During October of 1991, one of the prototypes was extensively damaged by a fire brought about from a hard carrier deck landing. Though this airframe was reclaimed, its flying days were over as it served out the rest of its tenure as a display piece.
As built, the Yak-41 was an impressive aircraft for her time. Performance specifications included a maximum speed of over Mach 1.4 (approximately 1,120 miles per hour) with a ferry range out to 1,865 miles, a service range out to 1,300 miles, a service ceiling up to 50,855 feet, and a rate-of-climb of 49,215 feet per minute.
Also in October of 1991 the Soviet Navy announced that the Yak-41 program would not be furthered (this coming during the tumultuous days of the fall of the Soviet Empire, a period in which the Soviet military suffered greatly from budget cuts). The proposed Yak-41M, expected to be the production model, was therefore not brought along. This mark would have incorporated an improved avionics suite as well as Leading-Edge Root Extensions (LERXs) at the wings. An alternatively-engined mark - the Yak-43 - also fell to naught. This would have carried a Kuznetsov/Samara NK-321 series engine (from a Tupolev Tu-160 bomber) and RD-41 lift engines. Yak-41U was to become a two-seat trainer to help reveal the intricacies of VTOL flight to incoming Russian naval pilots.
American defense-industry powerhouse Lockheed involved itself with the Yak-41 program for a short time in the early 1990s, this as the company was working on selling the USAF with its own VTOL-minded fighter product, the X-35 (to become the F-35 "Lightning II"). Beyond a last showing of prototypes 48-2 and 48-3 in 1993, the Yak-41 product fell to history after only two aircraft made up the line (not counting the two static/test members) - it was never adopted for Russian Navy service.