Underwhelming Avionics? An Analysis of Alleged Su-75 “Checkmate” Radar Specifications

Introduction

The Sukhoi Su-75 “Checkmate,” first unveiled at the MAKS-2021 air show, has been positioned by the United Aircraft Corporation (UAC) as a cost-effective, fifth-generation light tactical fighter aimed primarily at the export market. Marketing materials have consistently touted its high operational range, payload capacity, and advanced avionics suite.

However, recent documentation surfacing within defense circles—specifically an image of a non-secret export catalog circulating on Iranian Telegram channels—has raised concerns regarding the actual capabilities of the aircraft’s onboard radar. If accurate, these specifications suggest performance metrics that lag significantly behind modern standards and, in some parameters, fail to surpass Cold War-era interceptors.

The Alleged Specifications

The data in question outlines the detection range of the Su-75’s onboard radar system. According to the leaked document, the radar possesses a detection range of 160 kilometers for a target with a Radar Cross-Section (RCS) of 5 square meters in the frontal hemisphere.

In the context of aerial warfare, a target with an RCS of 5 m² generally represents a standard, non-stealth fourth-generation fighter jet (comparable to an F-16 or MiG-29 without reduced observability treatments).

Historical Benchmarking: A Regression in Capability?

To understand the skepticism surrounding these figures, it is necessary to benchmark the Su-75 against historical platforms. The alleged performance of this “promising” modern fighter appears comparable to, or arguably weaker than, heavy interceptors from the 1970s and 1980s.

• The F-14 Tomcat (USA, 1972): The Hughes AWG-9 radar utilized by the F-14 was capable of detecting a target with an RCS of 5 m² (or slightly less) at ranges of approximately 213–215 km when operating in high pulse repetition frequency (HPRF) mode.
• The MiG-31 (USSR, 1981): The capabilities of the “Zaslon” passive electronically scanned array (PESA) radar are well-documented. Official data suggests a detection range of 160–180 km for similar sized targets (5m²), typically citing a detection probability (P_d) of 0.5.

While it must be acknowledged that the F-14 and MiG-31 were heavy interceptors capable of carrying massive radar apertures and power supplies, the Su-75 benefits from fifty years of technological advancement. The expectation for a modern Active Electronically Scanned Array (AESA) radar—even one housed in a smaller nose cone—is that signal processing and efficiency should yield superior results to vacuum-tube or early solid-state era technology.

Comparison with Contemporary Russian Platforms

The concern is amplified when comparing the Su-75 to current Russian frontline aviation. The Su-75 is intended to operate alongside the heavy Su-57 and complement the Su-35S.

• Su-35S (Irbis-E Radar): The Irbis-E is a powerful PESA radar. Sukhoi claims detection ranges significantly exceeding 160 km for standard fighter-sized targets, often citing ranges up to 350–400 km for larger targets in specific search modes.
• Su-57 (N036 Byelka): As a fifth-generation platform, the Su-57 utilizes a sophisticated AESA suite. While specific classified data varies, its detection capabilities for standard targets are widely accepted to be superior to the figures leaked for the Su-75.

Operational Implications for Future Combat

The primary critique of the 160 km detection range lies in the nature of the modern battlefield. The Su-75 is marketed as a fighter for the future, where it must engage not only legacy aircraft but also:

1. Low-Observable (Stealth) Aircraft: Targets with an RCS of 0.1 m² to 0.001 m²
2. Cruise Missiles: Low-altitude, low-RCS threats.
3. UAVs: Small composite drones.

If a radar struggles to detect a large, “bright” 5 m² target beyond 160 km, its detection range against a stealth target (0.1 m²) would likely be reduced to distances that place the Su-75 well within the engagement envelope of enemy missiles, effectively nullifying its first-look, first-shot advantage.

Potential Technical Nuances

There are potential explanations for these modest figures that do not necessarily indicate a failure of engineering:

1. Probability of Detection (P_d): Soviet and early Russian specifications often utilized a P_d of 0.5 (50% chance of detection). If the Su-75’s 160 km figure is based on a stricter Western standard (e.g., P_d of 0.9 or 90%), the actual performance would be significantly higher than the raw number suggests when normalized against older radar stats.
2. Export Limitations: It is common practice for nations to downgrade the avionics of export variants (“monkey models”) to protect sensitive domestic technology. The catalog may reflect a degraded version of the radar intended for specific clients, rather than the domestic Russian Aerospace Forces version.

Conclusion

The leaked specifications regarding the Su-75 Checkmate’s radar performance present a paradox. For a fighter marketed as a cost-effective alternative to the F-35, possessing radar capabilities ostensibly inferior to 1970s interceptors is a significant marketing and operational liability.

Unless these figures represent a highly conservative estimate based on near-certain detection probabilities (P_d > 0.9), or are specific to a heavily downgraded export variant, they raise serious questions about the utility of the aircraft in a modern environment dominated by low-observable threats. It remains imperative for official sources from UAC or Rosoboronexport to clarify these specifications to alleviate concerns regarding the project’s viability.