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Russian 5th-Generation Fighters: MiG 1.44, Sukhoi S-37, & Sukhoi T.50

v1.0.1 / 01 feb 16 / greg goebel

* In the late 1980s the Soviet government initiated studies on "fifth generation" fighters to replace the current Mikoyan MiG-29 and Sukhoi Su-27. The collapse of the USSR threw such plans into confusion, but development efforts did continue, with the Mikoyan organization flying a "MiG 1.44" fighter demonstrator and the Sukhoi organization flying an "S-37" demonstrator with forward-swept wings. By 2010, the Russian fifth-generation fighter effort had led to the "Sukhoi T-50", which is to enter service with the Russian Air Force. This document provides a survey of the MiG 1.44, the Sukhoi S-37, and the Sukhoi T-50.

Sukhoi T-50


[1] MIKOYAN MIG 1.44
[2] SUKHOI S-37 BERKUT
[3] SUKHOI T-50
[4] COMMENTS, SOURCES, & REVISION HISTORY

[1] MIKOYAN MIG 1.44

* In 1986, the Soviet government initiated a "Multirole Tactical Fighter (MFI in its Russian acronym)" program to counter Western efforts to develop next-generation fighters, such as the US "Advanced Tactical Fighter (ATF)", which would become the Lockheed Martin F-22 Raptor. Ironically, it was Western fears that the Soviets were working on a fifth-generation fighter that drove the ATF program -- self-fulfilling prophecies were involved.

The Mikoyan experimental design bureau (OKB in its Russian acronym) set up an MFI design team to meet the requirement, originally led by Grigoriy Sedov and later by Yuri Vorontnikov. Early aerodynamic tests were carried out with radio-controlled glider models, each weighing about half a tonne (1,100 pounds), that were dropped from helicopters. Initial MFI prototype construction began in 1989, with the prototype finally rolled out in early 1994. It performed taxi trials later that year, but the program then bogged down to a halt, to remain in darkness for the next several years. Rumors circulated in the West about the secret "MiG 1.42", along with speculations about its features. However, work on the MFI was only dormant, not dead, and the demonstrator, designated the "MiG 1.44", was finally unveiled to the world in January 1999. The MiG 1.42 code was actually for the projected follow-on production version.

Mikoyan MiG 1.44

The MiG 1.44 was based on aerodynamic concepts devised at the Soviet Central Aerodynamics & Hydrodynamics Research Institute (TsAGI in its Russian acronym). It looked something like the offspring of the Mikoyan MiG-29 and the Eurofighter Typhoon, the European contribution to the fifth-generation fighter exercise. The MiG 1.44 shared the Typhoon's canard layout, an unusual configuration by Russian standards, and the twin belly engine intakes, but it was clearly not a Eurofighter copy.


   MIKOYAN MIG 1.44 (ESTIMATED SPECS):
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                15 meters           49 feet 2 inches
   length                  19 meters           62 feet 4 inches
   height                  4.5 meters          14 feet 9 inches

   empty weight            18,000 kilograms    39,700 pounds
   normal loaded weight    28,000 kilograms    61,750 pounds
   maximum takeoff weight  35,000 kilograms    77,200 pounds

   max speed at altitude   Mach 2+
   service ceiling         20,000 meters       65,600 feet
   range                   4,000 kilometers    2,500 MI / 2,150 NMI
   _____________________   _________________   _______________________

The wings were of cropped delta configuration, with a 45-degree sweep. They had full-span leading edge flaps and big two-section elevons in the rear. The large canards were placed behind the canopy, and had a dogtooth leading edge. Unlike the Eurofighter and like the MiG-29, the MiG 1.44 had twin tailfins with a slight outward cant. There were fixed ventral fins under tail, matching the tailfins.

The MiG 1.44's lines reflected some degree of "stealth" design, and a production version was to be coated with "radar absorbing material (RAM)" to improve stealth. The aircraft was powered by twin Lyul'ka-Saturn AL-41F bypass turbojets with an afterburning thrust of 175 kN (17,840 kgp / 39,340 lbf) each. The engines gave the MiG 1.44 a "supersonic cruise" capability, and had thrust-vectoring nozzles as well.

The MiG 1.44 had twin-wheel nose gear that retracted backward, while the single-wheel main gear retracted forward. The demonstrator lacked most combat avionics systems, though it did feature an advanced fly-by-wire (FBW) control system and was fitted with a GSh-301 30 millimeter cannon. In the production version, stores were to be carried in a weapons bay in the center fuselage, though the demonstrator didn't have this feature. Munitions could also be carried on external stores pylons.

MiG 1.44 versus MiG 4.12

The MiG 1.44 performed its initial flight on 29 February 2000, with test pilot Vladimir Gorbunov at the controls. It flew one more test flight, and then the program was canceled, with the demonstrator being mothballed. The MiG OKB had considered a two-seat version, as well as a "lightweight fighter" designated the "MiG 4.12" that had much the same configuration as the MiG 1.44 but was smaller, with a single engine. That seemed to be an end to the matter for over a decade.

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[2] SUKHOI S-37 BERKUT

* During the 1980s, the Sukhoi OKB explored possible follow-ons to the organization's successful Su-27 "Flanker" heavy fighter. From late in the decade work focused on the "Su-37", a strike fighter with canard foreplanes and cranked-arrow delta wing, with a single engine and intakes under the wing roots. It would carry a heavy warload on underwing pylons, though it would also have adequate performance to take care of itself in air-to-air combat. There was considerable interest in the Su-37, but due to the collapse of the Soviet Union, the program never went anywhere. The Su-37 designation was reused later for an Su-27 derivative.

In parallel with work on the Su-37, the Sukhoi OKB investigated a next-generation air-superiority fighter, focusing on a "forward swept wing (FSW)" design originally designated the "S-22". The FSW configuration was known to provide advantages in aerodynamic efficiency, handling, and maneuverability; it had never seen much use, however, because it imposed too much on the wings, meaning they would have to be heavily reinforced, raising weight and eliminating the advantage of the scheme. The availability of composite materials suggested to Sukhoi engineers that it had finally become practical to build an FSW fighter.

Although the Soviet government decided to focus on the Mikoyan OKB's fifth-generation fighter effort, which would lead to the MiG 1.44, the Sukhoi OKB was allowed to continue investigations in parallel. The S-22 design had proved unworkable, and in the absence of a requirement was a nonstarter anyway, so Sukhoi engineers went on to a derivative FSW naval fighter, the "S-32". With the collapse of the USSR, the S-32 program became uncertain; the Sukhoi OKB decided to focus on a relatively simple demonstrator, the "S-37", based on the S-32, and see where things went from there.

As it emerged, the S-37 was about the same size as as Su-27, and leveraged off Su-27 assemblies including the forward fuselage, landing gear, and tailfins. The S-37 of course differed substantially from the Su-27 with the forward-swept wings, which featured a leading-edge sweep of 20 degrees. The wing had a one-piece flap inboard and an aileron outboard on the trailing edge of the wing, plus a drooping leading-edge flap. The S-37 also had all-moving canard foreplanes ahead of the wings. The tail arrangement featured all-moving tailplanes, and twin tailfins with rudders.

Sukhoi S-37 Berkut

The S-37 was to be powered by two Solovyov D30F-11 afterburning bypass turbojets -- modified from the D30F-6 engines used on the Mikoyan MiG-31 interceptor, and providing kN (15,600 kgp / 34,390 kgp) each -- initially, to move up to more powerful AL-41F engines with thrust-vectoring exhausts when they became available. The engines were fed by semicircular engine intakes along the sides of the forward fuselage. The demonstrator would not be fitted with full combat kit and would be unarmed, though it did have a weapons bay in the belly. The S-37 was an inherently unstable aircraft that was kept in controlled flight using a fly-by-wire system. The Berkut was so large that its wings folded to allow it to fit into Russian hangars.


   SUKHOI S-37 BERKUT:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                16.7 meters         54 feet 9 inches
   wing area               61.87 sq_meters     666 sq_feet
   length                  22.6 meters         74 feet 2 inches
   height                  6.3 meters          20 feet 8 inches

   empty weight            16,375 kilograms    36,100 pounds
   normal loaded weight    25,000 kilograms    55,115 pounds
   maximum takeoff weight  35,000 kilograms    77,160 pounds

   max speed at altitude   Mach 2+
   service ceiling         18,000 meters       59,050 feet
   range                   3,300 kilometers    2,050 MI / 1,780 NMI
   _____________________   _________________   _______________________

Two prototypes were ordered, though only one was built. The "Berkut (Golden Eagle)", as it was nicknamed, performed its initial flight on 25 September 1999, with test pilot Igor Votintsev at the controls. It put on a display for the public at the Moscow MAKS airshow in August.

Although the Sukhoi organization promoted a production "Su-47" version of the S-37, the Berkut never went beyond the demonstration phase. It did put in appearances at the MAKS airshow in 2001, 2003, and 2005; by that time, interest had moved on to what would become the Sukhoi T-50, discussed below, with the S-37 used for tests of T-50 subsystems.

* While the Sukhoi OKB was working on the S-22 and then the S-32 FSW fighters in the 1980s, the organization also performed design studies for a smaller, single-engine FSW fighter along the lines of the S-37. Not much is known about it, the only released information being photos of wind-tunnel test models, and it doesn't appear to have gone very far.

Su-35 versus S-54/56

However, the Sukhoi OKB was much more earnest about a series of more conventional designs for single-engine fighter, the "S-54", with a complementary "S-56" carrier-based variant. The tale is a bit confusing because the S-54 designation was also used for earlier designs of an advanced trainer, but as the S-54 emerged, it looked very much like an advanced derivative of the Su-27 such as the Su-30, with the same general arrangement featuring canard foreplanes.

The S-54 differed substantially in having about half the empty weight and a single engine -- initially an AL-31F, later an AL-41F -- with a wedge-style inlet on the belly. The S-56 was similar to the S-54 but added carrier kit and folding wings -- double folding wings, to give an absolutely minimal footprint on a carrier. The rationale behind the S-54/56 was to offer a cheaper fighter for users who couldn't afford the Su-27. There was fair interest in the concept, but nobody wanted to fund it, and it went nowhere.

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[3] SUKHOI T-50

* The Sukhoi organization's work on a fifth-generation fighter didn't stop with the S-37. In 2001, the Russian government announced a fifth-generation fighter effort under the "Future Air Complex for Frontal Air Forces (PAK-FA in its Russian acronym)" program, specifying an aircraft that could compete with the emerging US Lockheed Martin F-35 Joint Strike Fighter, for introduction to service from 2010. A group of Russian industries led by Sukhoi and another group led by the Mikoyan and Yakovlev organizations competed for the PAK-FA contract; in late April 2002, the Russian government announced that the Sukhoi group had won the award.

Although there were repeated delays in getting the T-50 off the ground, the aircraft's maiden flight finally took place on 29 January 2010, with test pilot Sergey Bogdan at the controls. The T-50 was publicly unveiled at the Moscow MAKS airshow in that year, 2011.

To no surprise the Russians haven't been entirely forthcoming with details about the T-50, but some information has been released, and more could be obtained from videos of the aircraft -- the Russians have been generous in showing off the machine to the public and there's no lack of good imagery. It is a large single-seat twin-engine aircraft, looking something a hybrid of the Su-27 and the US F-22 Raptor, less stealthy but said to be more agile than the F-22.

The T-50 has mid-mounted trapezoidal wings with prominent "leading-edge root extensions (LERX)", along with trapezoidal tailplanes and twin tailfins. Each engine is in a nacelle under the wingroots, straddling the fuselage, with a prominent "stinger" between them in the rear, presumably for defensive systems. Composites are used extensively on the T-50, making up a quarter of its weight, and titanium is used extensively as well.

The engines are Saturn AL-41F1A afterburning bypass turbojets. Each AL-41F1A provides 86.3 kN (8,800 kgp / 19,400 lbf) dry thrust and 142 kN (14,500 kgp / 32,000 lbf) afterburning thrust. They are fed through rectangular, raked inlets and have independent vectorable exhausts. They feature full authority digital engine controls (FADEC), and support non-afterburning supersonic cruise. An improved derivative is expected for production machines.

Sukhoi T-50

The wings feature trailing-edge ailerons and one-piece flaps; there is a drooping leading-edge flap on the leading edge of the wing, both for takeoffs and combat maneuvering; and a drooping control surface at the front of each LERX as well, referred to as a "leading edge vortex controller (LEVCON)". The tailplanes and the tailfins are of "all-moving" configuration. The T-50 has tricycle landing gear, with twin-wheel nose gear and single-wheel main gear retracting into the sides of the engine nacelles; all gear retracts forward. The T-50 can deploy twin cruciform brake chutes out of a pop-up hatch on top of the tail stinger.

The pilot sits under a back-sliding canopy on a Zvezda zero-zero ejection seat, using a "glass cockpit" dashboard with a head-up display (HUD). The T-50 is built around advanced avionics, including an N036 Byelka (Squirrel) "active electronic scanning array (AESA)" radar, built by NII Tikhonravov; mission computer with sophisticated software; an "infrared search and track (IRST)" sensor mounted as a "wart" on the nose just in front of the windscreen; a datalink system; and electronic defensive systems, including radar warning, missile warning, and active jamming systems, plus chaff-flare dispensers. Early prototype configurations lacked most operational avionics, kit being methodically upgraded through the course of the trials process.


   SUKHOI T-50 (ESTIMATED SPECS):
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                14 meters           46 feet 7 inches
   wing area               78.8 sq_meters      848.1 sq_feet
   length                  19.8 meters         71 feet 2 inches
   height                  6.05 meters         19 feet 10 inches

   empty weight            18,500 kilograms    40,785 pounds
   normal loaded weight    26,000 kilograms    57,320 pounds
   maximum takeoff weight  37,000 kilograms    81,570 pounds

   max speed at altitude   Mach 2+
   service ceiling         20,000 meters       65,600 feet
   ferry range             5,500 kilometers    3,415 MI / 2,970 NMI
   _____________________   _________________   _______________________

The T-50 has twin tandem weapons bays in the "tunnel" between the engine nacelles, each about 5 meters (16 feet) long; there is also a "stealthy" fairing, presumably for weapons carriage, under each wing just outboard of the engine nacelles. There are two hardpoints under each wing for external stores, for a total of four; it appears that a store can also be attached under each engine nacelle. Reported maximum stores load is 7,500 kilograms (16,530 pounds), though obviously only a fraction of that can be carried internally. Potential weapons fits include:

Other munitions, such as antiship missiles, could be carried on the underwing pylons. It is difficult to find any pictures of the T-50 showing external stores; presumably it can haul external tanks, but configurations are not known. It does have a pop-out inflight refueling probe on the left side of nose. The T-50 has built-in armament, in the form of a single 30 millimeter cannon firing out the side of the fuselage to the right and below the cockpit -- though it wasn't fitted in the prototype initially.

Five T-50 prototypes were flown up to late 2013. Due to economic and technical problems, the T-50 program is slipping out, with fielding not expected before 2020; in the meantime, the Sukhoi Su-30SM and Su-35S are plugging the gap in VVS service.

The T-50 is also the basis for India's "Fifth Generation Fighter Aircraft (FGFA)", which will tweak the design to Indian requirements, with two seats presumably with some local content. Preliminary design of the FGFA was completed in early 2015; introduction to service will be no earlier than 2022.

In late 2013, the Russian government announced that work was being conducted on development of a single-engine lightweight fighter to complement the T-50, to increase the number of aircraft available to the VVS, and also for sale on the export market. The MiG organization was tasked with development, suggesting work on a MiG 1.44 derivative with leverage off T-50 technology. No schedule has been given. The Sukhoi organization has also mentioned preliminary work on an attack drone derived from the T-50, with first flight no earlier than 2018.

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[4] COMMENTS, SOURCES, & REVISION HISTORY

* Although the jury is clearly still out on the Sukhoi T-50 and will be for some time, I have to personally observe that I like its looks. Stealthy aircraft tend to have smoothly curved lines, which tends to give them a bland appearance; I find the T-50 has rather more style.

Sukhoi T-50

* As concerns copyrights and permissions for this document, all illustrations and images credited to me are public domain. I reserve all rights to my writings. However, if anyone does want to make use of my writings, just contact me, and we can chat about it. I'm lenient in giving permissions, usually on the basis of being properly credited.

* Sources include:

The online Wikipedia was consulted as well.

* Revision history:

   v1.0.0 / 01 mar 14
   v1.0.1 / 01 feb 16 / Review, updates, & polish.
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