我问：
Is it true that stealth aircraft usually flies in subsonic speed in combat missions even if it is capable of super cruise?
ChatGPT回答：
Yes, stealth aircraft typically fly at subsonic speeds during combat missions, even if they are capable of supercruise (sustained supersonic flight without afterburners). This is primarily because subsonic flight better supports the key advantages of stealth, fuel efficiency, and mission effectiveness. However, the choice of speed depends on mission requirements and the threat environment.
Reasons for Subsonic Operation in Combat Missions
1. Preservation of Stealth
• Infrared Signature: Subsonic speeds reduce engine heat and aerodynamic friction, minimizing the aircraft’s infrared signature, which is crucial for avoiding detection by IRST (Infrared Search and Track) systems and infrared-guided missiles.
• Radar Cross-Section (RCS): Stealth performance is optimized at subsonic speeds, as higher speeds can create airflow disturbances (e.g., shockwaves or turbulent wakes) that momentarily increase radar visibility.
2. Fuel Efficiency
• Extended Range and Loiter Time: Subsonic flight uses less fuel compared to supercruise or supersonic flight, allowing the aircraft to travel longer distances or spend more time on station for reconnaissance or targeting.
• Mission Flexibility: Conserving fuel during subsonic flight leaves more capacity for high-speed maneuvers during critical mission phases, such as evasion or attack.
3. Minimizing Detection Risks
• Acoustic Signature: Supersonic flight generates a sonic boom, which can alert adversaries to the aircraft’s presence. Subsonic speeds avoid this.
• Contrail Formation: Lower speeds and altitudes help minimize the formation of contrails, which could visually reveal the aircraft.
4. Sensor Effectiveness
• Optimized Sensor Performance: Subsonic flight allows onboard sensors, such as radar and electro-optical systems, to function more effectively. Rapid supersonic speeds can limit the time available for detailed reconnaissance or targeting.
5. Mission Coordination
• Synchronization with Other Assets: Subsonic flight enables better coordination with other forces, such as electronic warfare platforms, tankers, or ground units, to enhance overall mission success.
• Engagement Planning: Slower speeds provide more time for precise planning and execution of attacks.
When Supercruise is Used in Combat
• Rapid Egress: After completing a mission, stealth aircraft may engage supercruise to minimize exposure to enemy defenses during exfiltration.
• Time-Critical Missions: Supercruise is valuable for missions requiring rapid response or interception.
• Avoiding Threats: In high-threat scenarios, supercruise can be used to evade enemy aircraft or missiles by quickly exiting the engagement zone.
Examples
• F-22 Raptor: Capable of supercruise, but typically flies subsonic during air dominance operations to maintain stealth unless a high-speed response is required.
• F-35 Lightning II: Prioritizes subsonic stealth during most combat missions, using its stealth and sensors for first-look, first-shot capabilities rather than speed.
Conclusion
Stealth aircraft generally prioritize subsonic flight during combat missions to maintain their stealth advantage, optimize fuel usage, and reduce the likelihood of detection. While supercruise is a valuable capability, it is typically reserved for specific situations where speed is critical, such as escaping a threat or responding to time-sensitive targets.
