06/15/2026
Original engineering blueprints, handling studies, and official performance sheets for the Sukhoi Su-15 "Flagon" remain historically restricted or housed in deep state archives. However, a substantial body of technical data and flight mechanics reports has been compiled from declassified OKB Sukhoi records and military aviation museums.
Below is the comprehensive technical profile of the aircraft synthesized across its main engineering dimensions.
✈️ Aerodynamic Reports
Early Su-15 models encountered severe aerodynamic stability issues at lower speeds, which led to significant changes in later production blocks:
The "Cranked" Delta Wing: The initial pure-delta wing caused dangerously high landing speeds. Engineers replaced it with a double-delta (cranked) wing. This modification extended the outer wingspan and reduced wing loading.
Boundary Layer Control: The aircraft utilized a flap-blowing system (SPS). It tapped high-pressure air from the engine compressors and blew it over the trailing-edge flaps. This technical adjustment slashed landing speeds down to 325 km/h.
Aileron Performance: To maintain high-speed control authority and counteract roll lag within the flight envelope, engineers modified the aileron travel limits, increasing them from 15° to 18°30'.
⚙️ Engine Technical Notes
The Su-15 was the first Sukhoi interceptor to adopt a twin-engine layout, chosen for its supreme thrust profile and redundancy:
Powerplants: Standard operational variants relied on two Tumansky R-13F2-300 afterburning turbojets.
Thrust Performance: Each engine delivered 15,873 lbs of thrust (\(69.63\text{ kN}\)) under full afterburner.
Air Intake Management: Intake ramps used the automated UVD-58M control system. This mechanism dynamically altered the ramp angles to optimize supersonic airflow directly into the engine faces.
🕹️ Handling & Stability Studies
The aircraft was built exclusively as a point-defense, Ground-Controlled Interception (GCI) platform:Structural Load Factor:
The airframe was certified to a maximum structural limit of +6.5G. This limits its role to wide, sweeping bomber-intercept trajectories rather than tight dogfighting.
Automated Flight Control: The avionics integrated a Lazoor GCI command link. In its peak evolution (Su-15TM), the plane featured a fully automated flight mode. Ground radar stations could steer, climb, and guide the aircraft to its missile launch envelope without the pilot touching the flight controls.
Low-Altitude Limits: Aerodynamic drag from the un-slanted fuselage line and high wing loading created handling penalties at transonic low altitudes. It performed smoothly only when fully subsonic or cleanly supersonic.
📊 Performance Data Sheet
Parameter Performance Metric
Maximum Speed Mach 2.1 (\(2,230\text{ km/h}\)) at \(12,000\text{ m}\)Maximum Speed (Dry)Mach 1.5 without afterburner
Rate of Climb\(228\text{ m/s}\) (\(45,000\text{ ft/min}\))
Service Ceiling\(18,100\text{ m}\) (\(59,380\text{ ft}\))
Takeoff / Stall Speed\(400\text{ km/h}\) / \(300\text{ km/h}\)
Combat Radius\(725\text{ km}\) (\(450\text{ miles}\))
Ferry Range\(1,700\text{ km}\) with external drop tanks
🛠️ Engineering Bulletins & Modifications
Radome & Radar Overhauls: Early variants deployed the Oryol-D58 radar. Due to nose-cone limits, later bulletins reshaped the entire front fuselage to house the more reliable, heavy Taifun-M radar array.
Landing Gear Upgrades: The nose landing gear was upgraded from a single wheel to a heavy twin-wheel design (\(620 \times 180\text{ mm}\)). This allowed the heavy fighter to operate safely on harsher, semi-prepared airfields.
Ejection Envelope: Original cockpits were modified to install the KS-4 ejection seat. This granted safe emergency escapes across the entire flight envelope, provided airspeed was above \(140\text{ km/h}\).
