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Sukhoi Su-37

New multipurpose single engine combat aircraft with canard. Combat load of an attack airplane combined with the agility of interceptor

According to unconfirmed information from well informed sources, the Soviet Design Bureau Sukhoi is working on the design of a new multipurpose combat aircraft Su-37. Unlike well-known MiG-29 and Su-27, which are basically the third generation aircraft, although they have surpassed it by many features, Su-37 is foreseen to be a "thoroughbred member of the fourth generation.

Su-37 cooperation project?

All technological advances featuring the fourth generation aircraft and fully applied on Su-37, should enable it to manage in various roles. With respect to the level of priority of its various missions, Su-37 is primarily intended to be a fighter-bomber. It should be capable of individual performing of day/night strike missions under all weather conditions and, as stressed, keeping the capability of dog fighting far behind the front line.

It is also foreseen for use in strike actions, tactical and reconnaissance missions, even

as a fighter-interceptor. Although other fourth generation aircraft are also multipurpose, Su-37 has most comprehensive and severe specifications. This wide and efficient combat use should be provided by completely new electronic system, armament and new approach to its flight characteristics and survivability.

Although modern fighters are far more adapted to the multipurpose use than the aircraft of earlier generations, it is clear that their efficiency in a given role is much lower compared to specialized aircraft. It is, therefore, realistic to assume that at least the super-powers can afford aircraft for particular purposes in order to raise the efficiency to the maximum. An argument in favor of this opinion is the fact that the USA have just selected a specialized tactical fighter (ATF), while the other special-purpose aircraft, the striker aircraft (it should have been A-12), is to wait for better times. Therefore, the reduction of budget on both sides requires a selective approach to too specialized aircraft. All this indicated that

Su-37 was not conceived as an aircraft which will become the new aircraft of the Soviet Air Force, but, first and foremost, as a basis for development of future specialized aircraft. Namely, the elasticity of the selected concept and performance and the present development level allow for Su-37 conversion to, e.g., conventional interceptor or conventional striker aircraft, retaining the satisfactory efficiency in other roles.

The USSR is facing the problem of financing the project in the conditions of a deep economic crisis. It became obvious that the development of modern fighter aircraft is too big a bite for smaller countries, irrespective of their aeronautical, tradition, scientific, technical and financial potentials. Some of them can be expected to accept the cooperation as the only, and the safest solution. Although this is only a speculation, further elaboration of this assumption could lead to a conclusion that the decision in favor of development of a multipurpose aircraft, in an indirect manner presents the industry like the Soviet one as a potential partner in possible cooperation with an industry of lower capabilities. This might make use of insufficiently employed scientific and technical capacities, and any of potential partners might get either multipurpose or specialized aircraft corresponding to their requirements.

By the same token, one can assume that Su-37 is intended to replace Su-25 striker aircraft, having almost double its capacity (88%), but being also heavier (somewhat more than by 40%). But, this will certainly not happen within next 5-8 years, because Su-25 is still sufficiently good for the purpose, and it is hard to expect that the development of Su-37 will be finished any sooner.

Aircraft type

Mempty

MTOW

Thrust (T)

Wing area (S)

MTOW/S

T/MTOW

Hard points

Combat load

Mempty/MTOW

 

tons

tons

kN

tons/m²

kN/tons

pcs.

tons

 

EFA

9.75

 

180

50.00

430

0.834

10

 

0.443

Gripen

3.60

8.00

80

16.50

480

1.020

6

 

0.450

Rafale

9.00

21.50

150

47.00

450

0.711

14

8

0.418

F-18

9.90

23.54

75

37.16

633

0.77

9

 

0.420

Su-27

16.5

30.00

255

64.00

470

0.85

10

6

0.550

Su-37

12.00

25.00

180

50.00

500

0.734

18

8.5

0.480

Selection of parameters

Although the designers of Sukhoi Bureau have applied the so-called three lifting surfaces in their latest models (Naval Su-27, business Sukhoi-Gulfstream), in Su-37 they have decide a conventional canard concept with expressly hybrid wing. The selected aerodynamic configuration falls within modern trends (Rafal, Eurofighter, Grippen), although there is an obvious influence of its predecessor Su-27 (integration of mid-fuselage with wing and the wing itself).

In view of its purpose, with the accent on air-to-surface missions, the selection of a single-engine concept is surprising; from the survivability aspect, the concept with two engines would be much more favorable.

Knowledge that Su-37 accelerates from 600 to 1100 km/h at an altitude of 1000 m in only 14 seconds, and that for acceleration to 1300 km/h it requires additional 7.2 seconds, knowing that its maximum speed at the sea level is around 1500 km/h, implies the conclusion that it requires the power plant with maximum thrust (in afterburner mode) of about 180 kN. The same value of the required thrust can be calculated starting from the assumption that Su-37 will have the maneuvering capabilities of modern interceptors, in view of its maximum take-off weight of 25 tons, i.e. estimated normal weight of 16-18 tons.

Even the latest Pratt&Whitney F-119 engine, selected to power ATF, does not have such a high thrust, and no such engine is known to exist in the USSR. The problem of achieving the required thrust would be relatively easy to solve by installing two engines. Still, the designers have decided in favor of a single-engine option, which indicates that they are counting on a new engine either in development or the development of which is yet to begin.

The geometric and aerodynamic parameters of the wing are evaluated by the iteration method, based partly on incomplete data, partially on energy equations and partly on similarities with Su-27 wing. Taking into account the maximum speed of Su-37 at the sea level, and estimating the drag resistance (Cx) at level somewhat higher than that of Su-27 (due to increase of wing tip zone effect), the result is a wing area of about 45 m². However, this would mean that the specific lift, at maximum load of 9 g, is up to 3000 kg.m², which is by about 10% more than on Su-27, which is not very likely to be achieved. Further analysis indicates the most probable wing area of about 50 m². With these area and weight figures, Su-37 still has relatively low specific load (around 500 kg/m² at MTOW, i.e. 360 kg/m² at Mnormal), which should provide for excellent maneuverability.

Sukhoi-37 trump cards

Electronic System

The USSR expects the avionics applied in Su-37 to finally bridge the technological gap between themselves and the developed countries existing in this field for a number of years. The avionics system assembly includes the radar system which should, even under severe radar the following:

The optoelectronic system enables night and day combat use of the aircraft and launching of laser and TV-guided missiles as well as guidance of anti-tank missiles.

Multi-channel thermal imaging system (similar to Western FLIR) located in a pod enables use of missiles guided by thermal imaging system at the distances from 100 to 150 km.

The components of the defense system, which is expected to make the enemy use of Air Defense system difficult, are:

Other electronic equipment located in pods, includes systems for photo, IR and TV reconnaissance.

Armament

The second trump card of Su-37 is the armament. As foreseen, Su-37 should carry, on 18 (!) hard points, up to 8300 kg of external stores, exceeding the famous US A-10 striker. Apart from Tornado, no other modern fighter made in the last 10 years has such a big carrying capacity; only F-16 has somewhat greater specific carrying capacity compared to Su-37 (Mload/MTOW).

Besides a 30 mm gun, it will be able to carry a wide range of armament, such as:

Survival System

Many steps where taken in to increase its survivability, most of all reduction of aircraft signatures (reduction of IR signature, noise reduction, application of STEALTH technology but only marginally). In conjunction with the defense system, these technological improvements and procedures should significantly increase the active safety making early detection of the aircraft by the enemy more difficult.

In order to increase the passive safety, when the aircraft is already hit, there is an armor for protection of the pilot, vital structural components, engine, as well as special materials for protection of fuel system and tanks (polyurethane foam plastic which prevents fuel explosion, but not its burning), the total weight being 800 kg.

The possibility of aircraft storing at smaller area by way of its wings folding (giving the span of 10.8 m) and use of the third category runways of 7-8 kg/cm² hardness, should also considerably increase the life of the aircraft in combat conditions.

Flight technical characteristics

Achieving of high level of flight technical characteristics should considerably increase the efficiency as well as survivability of this aircraft. This includes a high carrying capacity, short landing and take-off distance so as to be able to use insufficiently prepared or damaged runways and quickly arrive to the combat zone.

One of the main features of Su-37, according to the available data, should be short response time from standby (maximum combat readiness) or from air patrolling.

High maneuverability at low and medium altitudes and low fuel consumption provide for a big radius of action without refueling in the air. In accordance with the tactical requirements, refueling in the air is possible, although, according to the earlier statements from the Sukhoi Design Bureau, this operation is not in full accordance with their understanding of air missions over the front.

Technical characteristics

Length

17.5 m

Wing span deployed

11.8 m

Wing span folded

8.1 m

Wing area

50 m²

Height of apron

5.7 m

Internal fuel

8.31

Power plant

One 180 kN afterburning turbofan

Maximum speed at sea level

1500 km/h

Maximum speed at cruising altitude

M=2.0

Practical ceiling

17000 m

Combat radius in Lo-Lo-Lo mode, (flying altitude 100 m with 5 tons of combat load)

800 km

Load factor

+9g/−3g

Acceleration time at 1000 m altitude from 600 to 1100 km/h

14 s

Acceleration time at 1000 m altitude  from 1100 to 1300 km/h

7 s

Some hypothetical color scheme of Sukhoi Su-37




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