SUKHOI Su-57 MILITARY
Final sensor suite configuration
The latest aircraft, T-50-9, is the first to have a
sensor suite like production versions of the Su-
- Previous prototypes had only partial suites
and/or structural mock-ups of the sensors.
All the Su-57’s systems and sensors are
coupled and controlled by a central computer.
The Sukhoi Design Bureau is responsible for
systems integration, which is a novelty. In the
past, fire-control and flight navigation systems
were integrated by instrument manufacturers.
On Sukhoi fighters, this work was usually
entrusted to RPKB of Ramenskoye. The sensor
suite includes the Sh121 radio-electronic
system and 101KS electro-optical system. The
Sh121 suite developed by the Tikhomirov NIIP
institute in Zhukovsky comprises the N036
radar and the L402 electronic intelligence and
electronic countermeasures (ECM) suite. The
NIIP N036 Byelka (squirrel) radar has five active
electronically scanned arrays, three X-band
(37.5 to 25mm wavelength) and two L-band
(300 to 150mm wavelength), that together
control the airspace within the angle up to
270° (+/-135° from the aircraft’s axis). Use of
L-band radar in air-to-air mode is the T-50’s
main means of dealing with stealth targets,
which may be detected (but not targeted) by
radio waves longer than the X-band for which
the radar cross-section’s reduction is typically
optimised. According to the head of NIIP Yuri
Belyi, the N036 radar installed on T-50-9 was
the last one to be made by the experimental
production facility of NIIP’s design bureau at
Zhukovsky; subsequent aircraft will be fitted
with radars made by the GRPZ production
facility of Ryazan.
The L402 Gimalai (Himalaya) ECM suite
developed by the KNIRTI institute in Zhukov
near Kaluga and manufactured by the Signal
factory in Stavropol is provided with its own
aerials, but when working within the same
range of frequencies used by the radar it
utilises the N036’s arrays.
The 101KS Atoll electro-optical suite
produced by UOMZ in Yekaterinburg is
intended to provide full control of the space
around the aircraft in the optical range, as well
as self-defence against missile attack. The Atoll
includes the forward-looking 101KS-V infrared
search-and-track (IRST) sight, four ultraviolet
missile approach warning sensors (MAWS)
that cover the whole sphere around the fighter,
as well as two 101KS-O sensors that UOMZ
says are directional infrared countermeasures.
Another 101KS-P device comprises a small
imaging IR sensor to aid low-level flying and
landing. The related 101KS-N navigation and
targeting pod is under development for the
Su-57.
Shrinking production plans
In the official ‘Schedule of activity of Russia’s
Ministry of Defence for 2013-2020’ published by
the MoD in 2013, the PAK FA’s initial operating
capability and the launch of full-scale series
production were scheduled for December
31, 2016. This deadline was not met and the
document itself is no longer mentioned by
anyone. The president of UAC, Yuri Slyusar,
said days before MAKS that three more T-50
prototypes would have to be built for the
contracted research and development work and
the Komsomolsk-on-Amur plant will commence
deliveries of the initial batch of production-
standard fighters in 2019.
According to a press release published by
Sukhoi for MAKS 2017 currently: “... the
first stage of state trials is nearing its end...
Characteristics of stability and controllability
at subsonic and supersonic speed, at
low and high flight altitudes, as well as on
supercritical angles of attack are confirmed.”
The first stage of state trials is in fact not a
very advanced level of testing; it concludes
with the acceptance of the aircraft as a flying
vehicle. Only the completion of the second
stage, when mission systems and armament
are tested, allows the aircraft to be officially
entered on the air force’s inventory.
Russia expects to buy fewer Su-57s than
previously planned. On March 23, 2015, deputy
minister of defence Yuri Borisov visited the plant
at Komsomolsk-on-Amur and said that the air
force might buy fewer T-50s than planned in
the National Armament Programme for 2020
(GPV-2020), buying instead lower-cost Su-30s
and Su-35s. Russian media quoted a source
within the Russian MoD who stated the air force
will order only one squadron by 2020 (Russian
fighter squadrons have 12 aircraft), instead of
the 60 aircraft promised by GPV-2020.
One reason for the reduction in planned
Su-57 production is internal competition
from the latest versions of fourth-generation
fighters, particularly the Su-35. Apart from
the Su-57s stealth qualities, there is little to
choose between the two and the Su-35 is
constantly being improved. After Borisov’s
visit to Komsomolsk-on-Amur, the Russian
Ministry of Defence, which has already ordered
98 Su-35S and 116 Su-30SM fighters, issued
an official statement about reduction in the
number of PAK FAs to be ordered. Added to it
was the observation that “the Su-35 fighters of
the so-called fourth-plus generation show good
characteristics in the opinion of military pilots”.PAK FA 2.0
According to the aforementioned Sukhoi press
release, the PAK FA “will be the company’s
primary product on the market of aircraft
technology starting from 2020”. By this time
an upgraded jet, the so-called second stage
PAK FA is planned to be available. The updated
version will feature new izdeliye 30 engines; the
current AL-41F-1 engines (izdeliye 117) are in
fact upgraded AL-31 engines as fitted to the
Su-27.
An interesting presentation by the United
Engine Corporation from 2013 shows
production plans as they were then: 150
izdeliye 117 and 340 izdeliye 30 engines to be
built before 2025. That means production of
the first-stage T-50 was not planned beyond
the initial 60 aircraft (currently reduced to 12);
the remaining 30 engines are just enough
for prototypes and other trials. The other
number, 340 izdeliye 30s, is interesting.
Deducting, some engines for tests, suggests
that production of 150-160 second-stage T-50
fighters during 2020-2025 was planned. Now
the plans are undoubtedly being downsized.
The first demonstrator of the izdeliye 30
engine ran in a ground testbed on November
11, 2016. It is still claimed that flight trials of the
engine will begin in 2017.
The izdeliye 30 is a clean-sheet design
intended to offer increased thrust of 16–17
tonnes compared to 14.5 tonnes today, to
be lighter, and have fewer parts and lower
operating costs. Stealth features are to be
introduced. The engine’s cold section will
have a three-stage compressor (instead
of four as in the current 117 engine) and a
single-stage turbine; the hot section (engine
core) will have a five-stage compressor
(instead of a nine-stage one) and a single-
stage turbine.Sergey Bogdan and Sergey Chernyshev flew a demonstration which included aerobatics and an air-to-air
engagement. The demonstration was notable though not that dynamic due to flight envelope restrictions.
Both aircraft, T-50-2 and T-50-4, are prototypes built without the current upgrade.