Sukhoi S-54/S-55/S-56 Design Progression

S-54 Light Fighter

The experience drawn from air warfare shows the victory is gained by the
side that is capable of increasing its air power faster that the opponent.
This could not be done only through operating heavy fighters which are able
to accomplish various missions but have a serious disadvantage: in case of a
wide-scale war (the Yugoslav war has testified to the fact that such
scenarios are quite possible in the near future) even most developed
industrial nations would be unable to set up their mass production promptly.
Currently, the USAF plans buying only 339 fifth-generation Lockheed Martin
F-22 Raptor fighters, with their number being open for further reduction in
the future. Even if the Russia Ministry of Defence scraps up enough money to
start production of its own fighters of the same class, their number will
hardly exceed 200-300 units at best, which is not enough for sustaining a
more or less air war.
The Russian Air Force (RusAF) fighter fleet is obviously to comprise light
simple-to-fly fighters as well. Their mass production could be started fast
enough by the Russian aircraft industry prior to hostilities or during them.
The current level of aircraft industry ensures the development of such a
fighter - a kind of the MiG-21 of the 21st century - whose combat
capabilities would match those of the heavier Su-27, F-15 or F/A-18E/F. A
light, compact shipborne fighter would bolster aircraft carriers'
operational capabilities by increasing their aircraft complement by several
times. An important advantage of the prospective light fighter is his better
export chances as compared to those of the heavier fighters. Nowadays, the
latter (like the Su-27 or f-15) are operated by several countries only -
Russia, the US, China, India, Israel, Saudi Arabia, Japan. At the same time,
scores of nations operate lighter fourth-generation fighters, such as
MiG-29, F-16, F/A-18 and Mirage 2000. However, even these aircraft whose
takeoff weight exceeds 15 t could hardly be called 'light' per se, let alone
foreign new-generation fighters - EF2000, Rafale and F-22. As far as their
price is concerned, they 'weigh' here to much too - over $60 million. This
makes them unaffordable for most potential buyers.
In this situation, a range of countries, which have been aggressively trying
to carve up their niche on the global aircraft market - China, Germany,
India, south Korea, etc.), commenced work on lighter (10-12 t) and much
cheaper aircraft with a heavy emphasis being placed on exporting them.
However, the analysis of those prospective fighters shows they are going to
be inferior to upgraded Russian, US and European fighters.
The work on developing a new fighter (a whole new family of fighters,
actually - S-54, S-55 and S-56) has been underway at the Sukhoi design
bureau. Initially, the S-54 programme, started in 1990, provided for
development of a supersonic combat trainer intended for RusAF fighter pilot
training as well as for expert. The experience of making the Su-27 was
supposed to be drawn on in designing the S-54. However, the successful
upgrading of the Su-27 into the Su-33, Su-33KUB, Su-35, etc., as well as
progress in aerodynamics, avionics, engines, electronics, allowed the
developer to greatly bolster the potential capabilities of the prospective
aircraft by turning this combat trainer into a real fighter with its
performances matching or even exceeding those of the Su-27 and its cost and
weight being twice as less.
From the very beginning, the S-54 has been designed with a shipborne role in
mind. This provided for the folding wing, arrestor hook, anticorrosion
coating, etc.). Such an approach was caused by taking the world (mostly
American) experience in the naval aircraft developing, which says that it is
easier to turn a good shipborne fighter into a regular - ground-based - one
than to try to 'navalise' an Air Force fighter.
The technological solution provided for the S-56 shipborne fighter will
increase the carrier's fighter capacity by 2-3 times, thus enhancing the
carrier task forces' combat effectiveness and enabling them to win the war
of attrition waged with the enemy carrier groups.
The Admiral Kuznetsov performances determined the S-56's characteristics.
The point is the arrestor gear mounted on Kuznetsov are unable, due to
their inertia, to get operational if the weight of the aircraft landing is
less than 7 t - too hard longitudinal g-load during the breaking occur,
which can result in damaging the aircraft or the pilot, or both. Owing to
this, the regular S-56 take-off weight (with two medium-range AAMs and two
short-range AAMs) totalled 12 t - a little bit more than that of the latest
versions of the MiG-21 (8-9 t).
The S-54/55/56 aerodynamic configuration resembles that of the Su-33
fighter. It incorporates all-moving foreplanes and empennage, rather high
aspect ratio trapezoid wing joined smoothly with the airframe, twin tails.
However, there are certain differences. In comparison with the latest
version of the Flanker family - the Su-33KUB, the light fighter's
aerodynamics features considerable improvements. The wing became adaptive,
which led to enhancement of lift/drag ratio. To improve the fighter's
manoeuvrability, the tails and ventral fins were made all-moving and
positioned along the same axis.
The S-56 is going to be the most compact fighter across the world. The
developer strove to make the plane with its wings folded to fit the square
of 3 by 3 metres. This was achieved via the double folding of the wing that
folds at the point where it joins the airframe and in the middle of the wing
panel, with one section covering the other when folded. Another ingenious
solution was the 'squatting' landing gear. The nose strut is retracted
forward with a turn, while the main gear is turned rearward. With its
landing gear being semi-retracted, the fighter makes a kind of squat, which
reduces its height down to 3 m, which allows new ways of housing the
fighters on the carrier.
Between the hangar and the gallery decks, there might be appear an extra
deck, which would increase the number of fighter onboard by 2-3 times. To
house bigger planes (e.g. the Su-33) and helicopters, part of the hangar
deck might be preserved without modification.
The S-54/55/56 design does not make provision for the use of stealth
coatings as great as the design of US 5-generation F-22 and JSF's one does.
In particular, unlike the American aircraft, the Russian ones are going to
have their weapons mounted only externally. However, their stealthiness is
to be enhanced by the factor of 10 through more thorough integration of
weapons and the airframe, reducing the number of protruding parts, antennae,
rigging, as well as through the use of radar-absorbent coatings and
materials.
The S-55 twinseater the crew is seated shoulder-by-shoulder like at the
Su-24, Su-27IB and Su-33KUB. This makes the pilot training much easier and
simplifies the pilots' communication in flight. Despite the fighter's small
size, the seat pitch is the same as in the cockpit of the Su-24.
The S-54 is powered by a single AL-31 engine featuring three-dimensional
TVC. With its regular takeoff, the fighter's thrust-to-weight ratio exceeds
1 by far. In the future, when the aircraft is fitted with a new-generation
engine, it might produce non-afterburning supersonic cruising speed. The
S-54's internal fuel cells hold 4,500 kg of fuel, while the F-15 (twice as
heavier) can carry only 6,100 kg of avgas. This coupled with superior
aerodynamic characteristics gives the S-54 the service range of 4,000 km (as
compared, the F-15 has the service range of only 2,000 km when flown with no
drop tanks). The S-54 family fighters are going to be fitted with most
sophisticated avionics. The radar nosecone diameter equals that of the Su-27
(about 1 m), which allows a powerful phased array radar (PAR) to be mounted
on this light fighter to provide a detection range exceeding that of the
F-16C or JSF. The S-54's radar will be augmented by a new electro-optical
system comprising a low-level night system and capable of operating against
both air and surface targets.
Like other prospective Russian fighters, the S-54 and its versions are
expected to feature a powerful computer made of the Russian components and
able to make dozens of billions calculations per second. The cockpit
instrumentation layout is made with new principles in mind through the use
of multifunction colour LCDs (14-15 inches in diagonal).
The cockpit is planned to be fitted with an improved ejection seat derived
from the K-36 ejection seat. A new g-suit and a new oxygen supply system are
going to be provided to the pilots to enable the latter to be capable of
manoeuvring at 10-12 g. The crew will be provided with a new, lighter helmet
integrated with a helmet-mounted display.
Measures are being taken to cut the ground crew strength. Despite the
problems with funding, the work on the S-54 family planes has been underway,
however, the programme should be accelerated, since in several years the
Indian Navy is expected to include into its inventory the former Admiral
Gorshkov through-the-deck-cruiser converted into a full-scale aircraft
carrier.
The S-56 is an ideal aircraft to be stationed on this carrier, as well as on
the light air defence AD aircraft carrier slated for building at Indian
shipyards. However, should the Russian aircraft be late, the Indian ships
could end up carrying foreign-made fighters, e.g. production Rafale-Ms or
new versions of Harrier. The same might happen in China which soon is going
to get in possession of aircraft carriers. The Russian Air Force needs such
warplanes too. In the early 21st century, a cheap light fighter, whose
design has already been developed thoroughly enough, would enhance the RusAF
and Naval Aviation's combat readiness sharply and considerably and bolster
Russia's positions on the global aircraft market.

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overscan said:

The S-55 twinseater the crew is seated shoulder-by-shoulder like at the
Su-24, Su-27IB and Su-33KUB. This makes the pilot training much easier and
simplifies the pilots' communication in flight.

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Stargazer2006 said:

Comparison of the S-54 with Yakovlev's UTK-200 and the MiG-AT (artwork by A. Jurgenson), from Aviatsiya i Vremia N°90 (2007):

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flateric said:

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