The lack of the basic R-77’s characteristic “lattice” fins at the rear of both the missiles indicates that they are different versions of the weapon, but exactly which models the Su-57 is carrying is not entirely clear.
Russia first began the development of the original active-radar-guided R-77, also known as the Izdeliye 170, back in the early 1980s as a counterpart to the U.S. AIM-120 AMRAAM. It did not enter service before the collapse of that Soviet Union, only becoming part of Russia’s arsenal in 1994.
An improved R-77-1, Izdeliye 170-1, was subsequently introduced on Russian Flanker fighters and has been noted on combat operations during the air force’s operations in Syria. This weapon offers improved resistance to countermeasures, a more sensitive seeker, and aerodynamic refinements — the lattice fins at the rear are retained.
While the R-77-1 was viewed as an interim upgrade, the K-77M is the next stage in the development of the missile, with conventional control fins allowing internal carriage in the Su-57’s weapons bay. Doing away with the old grid fins not only permits internal carriage but also reduces the missile’s aerodynamic drag and radar cross-section.
Other changes include a new dual-pulse rocket motor and a further enhanced radar seeker. The dual-pulse engine ensures that thrust output is maintained throughout the missile’s flight profile, allowing improved high-altitude maneuvering, extended range, and enhanced endgame performance. Unconfirmed reports suggest that the K-77M offers double the range of the R-77; that would imply a range of up to 100 miles for the new weapon.
Vympel has claimed the K-77M will be superior to the AIM-120C-7 AMRAAM and equal to subsequent AMRAAM developments — presumably, the AIM-120D. The manufacturer has also claimed the new weapon is capable of engaging anti-aircraft missiles fired at the launch aircraft, even missiles approaching from the rear.
It’s important to note that although the K-77M was designed for the outset to be carried inside the Su-57’s internal weapons bay, Russian doctrine evidently sees a requirement for external stores in at least some situations. In a high-threat environment, fighting against a peer foe, it would be expected that the Felon carries its weapons internally, to reduce its radar cross-section. However, in less-contested environments, or in the latter stages of a conflict, after enemy air defenses have been suppressed, additional stores could be carried underwing. These might include external fuel tanks and other stores that might not fit in the weapons bays.
Russia is developing other air-to-air missiles that the Su-57 could carry internally, as well. This includes the Vympel K-74M2, or Izdeliye 760, intended for deployment from the aircraft’s internal “quick launch” weapons bays. This may, or may not be, the previously unseen compact weapon, pictures of which first emerged in November 2019. You can read more about these developments in these past War Zone stories, respectively.
For external carriage on the Su-57, and offering yet greater range than the K-77M, there is the secretive Izdeliye 180-PD, in which the suffix stands for Priamotochnyi Dvigatel, or ramjet engine in Russian. This is pitched as a Russian counterpart to the pan-European MBDA Meteor air-to-air missile and utilizes a combined rocket-ramjet powerplant. Reportedly developed as a private venture by Vympel, it’s unclear if the weapon has been ordered by the Russian Aerospace Forces.
Deployment of a rocket-ramjet air-to-air missile would be a significant boost for the Russian Aerospace Forces. In contrast to a normal rocket motor, this type of propulsion allows the missile’s engine to be throttled during different phases of flight, ensuring a high-energy state during the terminal attack phase. You can read more about the specific advantages of ramjet missiles in this War Zone article.
Previous images of the ramjet-powered Adder have been limited to mock-ups at arms exhibitions and unofficial artist’s impressions. As such, the available video evidence is insufficient to determine whether the Su-57 is carrying an example of the Izdeliye 180-PD and one K-77M, or two K-77Ms, or potentially other derivatives of the weapon.
Evidence in favor of the Izdeliye 180-PD includes what appears to be a ramjet air intake under the weapon furthest from the camera. However, the quality of the video is such that this could be a distorted view of one of the stabilizing fins on the missile’s center section.
R-37M for Su-35S
The other video footage that emerged recently, seen below, shows apparent trials of the very-long-range R-37M launched from a Russian Aerospace Forces Su-35S fighter, with the bort number “52 Red.” Previously, the R-37M was only known to be carried operationally by the MiG-31 Foxhound heavy interceptor and the weapon itself was very rarely seen.