The Su-27SM3 is the most advanced aircraft from the original Su-27 single-seater line. But Russia also fields significant numbers of advanced variants of the dual-seat Su-30: The Su-30M2 and Su-30SM.

While the Su-35 grabs the headlines as Russia’s most advanced fighter, the majority of its air force consists of older types. Per the International Institute for Strategic Studies’ (IISS) “The Military Balance 2018,” Russia operates around 220 “legacy” Flankers to seventy Su-35S, nearly triple the number. The “legacy” Flankers consist of a mix of original Su-27s, various SM upgrades of this type and twin-seat Su-30s. But how effective are these older Flankers? Are some versions near the capability of the Su-35S?

(This first appeared several months ago and is being reposted due to reader interest.)

The first type that Russia operates is listed by IISS as fifty airframes of “Su-27 Flanker.” Presumably, this is referring to the basic Su-27S that entered service in 1985. Also listed are ten airframes of the Su-27UB, which is simply a dual-seat version of this aircraft. This basic variant of the Flanker lacks serious capability relative to modern fighters at range as it has only an ancient radar.

The Su-27S is only capable of launching semi-active radar homing missiles, specifically the R-27, that require the fighter to point its nose at the target during the entire duration in which the missile is in flight. The R-27ER does bring a lot of range and some midpoint guidance functionality to the Su-27S, but it is still last gen technology that can’t take advantage of modern air-to-air combat tactics that utilize active-radar homing missiles.

It remains a potent force in closer-range dogfights with the natural maneuverability of the Su- airframe paired with the helmet mounted sight and the R-73 missile. However, while this off-boresight IR missile locking functionality was fairly revolutionary when it came out, newer American craft with AIM-9X and Joint Helmet Mounted Cueing System (JHMCS) have matched and surpassed this capability, being capable of locking up and shooting at greater angles than the basic Su-27S.

The air-to-ground capability of the Su-27S is very basic, being able to only employ unguided weapons. The fighter is listed as a pure “fighter” in “The Military Balance” for this reason; all other Flankers are listed as multirole.

The first Flanker in the multirole category is the Su-27SM, clocking in at forty-seven types. This was a basic modernization of the type, completed in 2003. The modernization mostly improved the functionality of the existing equipment on the Flanker with an avionics upgrade.

Recommended: What Will the Sixth-Generation Jet Fighter Look Like?

Recommended: Imagine a U.S. Air Force That Never Built the B-52 Bomber

Recommended: Russia's Next Big Military Sale - To Mexico?

Recommended: Would China Really Invade Taiwan?

A ground-mapping mode was added to the radar and guided air-to-ground weapons, including the KAB laser guided bombs and the Kh-29 series of missiles. The active radar homing R-77 missile was also integrated into the Su-27SM. New engines were also added to Su-27SMs modernized after 2007.

While the Su-27SM upgrade made the Su-27 into a true multirole aircraft, it was very much a “Band-Aid” upgrade done at low cost. A more comprehensive modernization is the Su-27SM3, fourteen of which are in service. The Su-27SM3 is not only a modernization, new Flankers are being built to the SM3 standard, though some sources state that these were built out of aircraft originally destined for the People’s Republic of China. The Su-27SM3 rolls together a lot of technology that was only seen on export Flankers prior.

The Su-27SM3 mounts the powerful Irbis-E radar, which is also used on the Su-35S. New engines are added, which give additional power and range. Additional hardpoints for weapons are also added, bringing the total number to twelve. To accommodate all these new features, the airframe is reinforced to allow for three more tons of armament to be hung from the aircraft.

The cockpit also undergoes a full modernization in the Su-27SM3, utilizing four multifunctional displays in place of the old school dials present in earlier Su-27 variants, and integrates a new radio complex to allow for more secure communications.

The Su-27SM3 is the most advanced aircraft from the original Su-27 single-seater line. But Russia also fields significant numbers of advanced variants of the dual-seat Su-30: The Su-30M2 and Su-30SM.

These advanced Su-30s are broadly similar to the SM3: they have integration with air-to-ground weapons, MFDs in the cockpit and improved engines. The primary advantage they have is the addition of thrust vectoring to the engines, making the aircraft even more maneuverable within certain flight envelopes. Su-30s also have twelve weapon hardpoints as standard. However, they don’t mount the powerful Irbis-E radar, making them potentially worse at tracking and engaging targets at long range.

The Su-35S, of course, has the best aspects of all the three latest fighters. It has more powerful thrust vectoring engines, the Irbis-E radar, a modern cockpit and can shoot almost the full complement of Russian air-to-ground weapons.

But the latest modernization of Russia’s lesser fighters is no slouch and has its advantages too: The Su-27SM3 is significantly cheaper than the Su-35S and provides practically the same long-range capability. The Su-30s are potentially better for strike missions given the distributed pilot workload.

The only catch is that the most modern designs; the Su-30M2, SM and the Su-27M3 only comprise about half of the legacy Flanker fleet. The other half are composed of Su-27S, SM and UB which possess greatly reduced capability in comparison. But it is expected that these will be slowly modernized, or be replaced by the new Su-57.

Charlie Gao studied Political and Computer Science at Grinnell College and is a frequent commentator on defense and national security issues.

Image: Reuters.