Notes:

As the war in Ukraine continues, we thought it would be interesting to discuss one aspect of the airpower used by both sides. While initial air combat occurred during the opening days of the war, there hasn’t been a lot of reporting about the situation in the air since. At the moment, both sides continue to fly different variants of the same aircraft – including the SU-25 and MIG-29 – but one of the lesser seen jets has been the Sukhoi 27, an aircraft which both sides have continued to use since the 1980s. We will make a brief comparison between both sides and how their SU-27s compare.

On the Russian side are many variants of the SU-27 still in operation, but within the context of the Ukraine war, the only version seemingly in combat is the Su-27SM, or Flanker-E. On the Ukrainian side are a number of variants, each with slightly differing abilities; these are the SU-27P, S, and UB variants.

UKRAINIAN

Beginning in 1991 with the dissolution of the Soviet Union, Ukraine inherited a fleet of Russian aircraft. Among them were roughly 70 SU-27s. Having issues with sourcing parts, half of the inventory was grounded and six of these were supposedly sold off. Today, it is reported that Ukraine is operating a total of 34 serviceable Su-27s. These early variants were at a clear disadvantage against more contemporary fighters; namely due to the lack of a modernised radar, multifunction displays, and the ability to use active radar guided missiles.

From 1991 to 2014, the Ukrainian SU-27 fleet was made up of three sub variants; the SU-27-UB, S, and P. Three upgrade programs were initiated in 2014 – although these were limited in scope. The goal was to modernise these aircraft and bring them up to NATO standards. These would be the SU-27-UB-1M upgrade for the SU-27-UB, the SU-27-S-1M for the SU-27S, and the SU-27P-1M for the SU-27-P. It is also possible that since the start of the war, other upgrade programs occurred without public announcement.

The biggest problem with these aircraft is that they lack fully integrated active radar systems. Most appear to retain support for earlier semi-active radar guided missiles. This is a key difference from the Russian aircraft and we will get into the details a bit later.

RUSSIAN

On the Russian side is the SM variant, the only SU-27 known to regularly operate in this current war. The SM variant offers several crucial improvements. Firstly, it is outfitted with modern multifunction displays, clearing much of the analogue cockpit clutter found in previous versions. This is driven by a more powerful computer, integrating a better electro optical system, and an upgraded radar. This upgraded mission computer allows the radar to generate synthetic aperture terrain mapping, and maritime target acquisition. Upgraded engines are also equipped on some models, whilst all SM variants can use laser guided bombs, and several air to surface missiles, including the KH-31 and KH-29. Two sub variants – the SM2 and SM3 – also exist, with slight upgrades as well.

A key advantage held by the Russian variant is its ability to carry active radar guided missiles. The most dangerous of these is the R-77, a BVR missile designed to compete with the AIM-120C. Other common loadouts include the active R-27EA and R-27ET infrared optical for medium range, and the R-73 Archer for close range. As highlighted by a Ukrainian MiG-29 pilot, the R-77 missile has given these Russian jets a distinct advantage.

KEY DIFFERENCES

The most important difference between the Ukrainian and Russian Sukhoi 27 variants is the integration of active radar guided missiles. In modern combat this is a necessary capability. The reason is simple; Ukrainian aircraft – with their semi-active radar guided missiles – require the launch aircraft to maintain lock with the target until the missile hits. The missile’s onboard computer cannot track the target on its own.

In contrast, most active radar guided missiles have onboard computers capable of locking and tracking the target autonomously. So, an aircraft equipped with active radar missiles can launch and then break away to go defensive. An aircraft with semi-active missiles cannot; they must hold lock with their aircraft, which usually means continuously flying towards the target, as the radar gimbal can only rotate so far.

To put this into perspective, in a modern BVR fight, an aircraft will usually turn cold, or go defensive after firing a missile if there is a possibility that an adversary has also fired a missile. Generally, a pilot wants to be flying at an angle no less than 90 degrees when going defensive against incoming missiles. Preferably, he would be flying in the opposite direction. A pilot firing a semi active missile cannot do this, as most radar gimbals cannot pan more than 90 degrees. If the target goes beyond the gimbal limit, the missile is useless.

A Ukrainian pilot – when interviewed – said that the lack of such “fire and forget” missiles was the greatest problem for the Ukrainian Air Force.

Another important difference is the integration of a datalink system in the Russian variant of the aircraft. This is not a necessary technology, but it does offer some major advantages for co-ordination.

The Ukrainians may still yet upgrade their aircraft in the future. Since the war started, both the SU-27 and MIG-29 underwent quick upgrade programs to accommodate AGM 88 anti-radiation missile to target SAM radars. There has also been some talk about an AMRAAM upgrade for both aircraft, although this seems unlikely. Integrating such weapons as AIM-120s into an eastern bloc aircraft would cost a considerable amount of time and money, as it would not only entail producing new equipment specifically for both the Mig and Sukhoi, but could also require radar upgrades and such.

CONCLUSION

With all of this considered, it is easy to see just how important the Russian upgrade programs have been for keeping the SU-27 current. For Ukrainian pilots, no amount of skill or training can improve radar capability, or missile tracking. The arrival of the F-16 in Ukraine may change this balance, although it is difficult to say. The F-16s being delivered, (mid-life upgrade A/B models),  are older than the Russian SU-27SMs, though they will at least have active guided missile capabilities. The challenge will then be utilising older AMRAAMs with their 50-mile range, against the 80 to 100 mile range of the MIG-31K and SU-35S equipped with R-77s. This will be important to consider given the thick anti-air coverage from both sides along the front lines, which encourages both sides to fire off BVR missiles while still in friendly territory before returning to base. For this reason, it does not seem realistic that – as many online have advocated for – the Ukrainians go on some sort of air offensive into Russia. This could be disastrous for the ageing fleet of Sukhois.

Nevertheless, even with these disadvantages, Ukrainian pilots have pushed these old aircraft to their limits. It is claimed – although it is hard to verify – that these old SU-27s continue to contest most of the Ukrainian air space. If this is true, then this is a particularly impressive feat, given what they are up against, and it highlights how these older designs can still be put to use in a defensive role.

As for the Russians, it is unlikely that the SU-27 upgrade programs will continue for too much longer. Despite its success as a design, many have been keen to move on from the SU-27, and onto newer designs such as the SU-57 and SU-75 checkmate. While export variants continue to be built, the SU-35 may mark the last major development domestically. Nicknamed the ‘Last Flanker’, the SU-35 will likely remain in service for some time, although from its inception as a spinoff of the SU-27M, it was always intended to be the interim aircraft awaiting the arrival of 5th and 6th gen designs.

Nevertheless, just like the F-15, the Flanker is somewhat symbolic of 4th gen fighters. It is still deadly and despite the hundreds of modern aircraft produced in recent years, it is likely that we will continue to see it in the air for decades to come. As for the Ukrainian Air Force’s technology deficit compared to the Russians, it remains to be seen what new airpower will be brought to the table, and what difference, if any, it will make for either side.