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1、飞机设计导论-第5讲 2021 Introduction to Aircraft DesignLecture5: Performance Analysis and Optimization Xu Weiqiang (徐伟强) Ph.D. Outline1 2 3 4 5 Performance requirements and development Flight envelope and regional division Aerodynamic and stability analysis Weight analysis Cost and other performance analysi
2、s multidisciplinary design optimizationSchool of Aeronautical Science and Engineering 6 Performance requirements and development Piston fighter Subsonic cruise( Flight speed is about M0.6 ) Liquid-cooled piston engine; Simple weapons( machine gun, canon ) P-51 School of Aeronautical Science and Engi
3、neering Performance requirements and development The first generation jet fighterF-86 Subsonic cruise( Flight speed is M0.95 0.98 ); altitude of about 15000 meters; Simple weapons( Infrared Air-to-Air Missile); Simple electronic devices; ejection seat; pressurized cockpit.MIG-15School of Aeronautica
4、l Science and Engineering Performance requirements and development The second generation jet fighterMig-19 Break the “sound barrier” ( The jet engine with afterburner, about M1.3 ); Certain weapons( cannon, simple air to air missiles ); Improved electronic equipment (small airborne radar). School of
5、 Aeronautical Science and Engineering Performance requirements and development The third generation jet fighterF-4 The maximum number of M reached 2 2.5; ceiling close to 20000 meters; Advanced fire control radar and navigation systems; advanced air to air missiles . MIG-21 School of Aeronautical Sc
6、ience and Engineering Performance requirements and development The fourth generation jet fighter Large thrust-weight ratio; Omnidirectional attack; Low-altitude transonic maneuverability; Long-range combat capability; Remote detection(up to 100 km above ); Fire control radar has a lookdown ejection
7、function; Can track multiple targets. F-15 Su-27 School of Aeronautical Science and Engineering Performance requirements and development The fifth generation jet fighter Supersonic cruise capability without open afterburner ; Low signature performance; High agility and maneuverability, especially th
8、e post-stall maneuver capability; STOL performance; Visual fighting over the horizon attack and ground attack capabilities; High reliability and maintainability F-35 S-37 School of Aeronautical Science and Engineering Performance requirements and development Cruise PerformanceA typical mission is il
9、lustrated below. The mission profile consists of two portions: the nominal mission and the reserves. Taxi and take-off:a period of about 15 minutes; There is a best altitude for cruise and this optimum altitude increases as the aircraft weight decreases (as fuel is burned). School of Aeronautical Sc
10、ience and Engineering Performance requirements and development ATC rules specify t hat aircraft be flown at specific flight altitudes; step cruise profile, with 1 to 3 steps of 4000 ft in altitude due to airway requirements; stepped profiles lead to reductions in cruise range by 1%-2%; Reserve fuel
11、is carried to allow for deviations from the original flight plan. 1. Fuel to fly 10% of planned block time at long range cruise speed; 2. Climb from sea level to cruise altitude; 3. Cruise to alternate; 4. Descend to 1500 ft and hold for 30 minutes; 5. Descend to sea level.School of Aeronautical Sci
12、ence and Engineering Performance requirements and development Range Number of Engines: Flight Condition: First Take-Off Segment Second Take-Off Segment Final Take-Off Segment Enroute Climb Approach Segment Landing Segment 4 0.5% 3.0% 1.7% 1.6% 2.7% 3.2% 3 0.3% 2.7% 1.5% 1.4% 2.4% 3.2% 2 0.0% 2.4% 1.
13、2% 1.1% 2.1% 3.2%School of Aeronautical Science and Engineering Required Climb Gradient (爬升梯度 ) Performance requirements and developmentSpecific Range = V / cT T = D = W / (L/D) Specific Range = V/c L/D 1/W Breguet Range Equation where V is the true speed, c is the thrust specific fuel consumptionSc
14、hool of Aeronautical Science and Engineering Outline1 2 3 4 5 Performance requirements and development Flight envelope and regional division Aerodynamic and stability analysis Weight analysis Cost and other performance analysis multidisciplinary design optimizationSchool of Aeronautical Science and
15、Engineering 6 Flight envelope and regional division SPECIFIC EXCESS POWER: School of Aeronautical Science and Engineering Flight envelope and regional division Typical Design Requirements for a Multi-Role Jet FighterMinimum performance requirements/constraints Item Combat mission radius Weapons payload Requirement 400 nautical miles 2 AIM-120 4 2000 lb MK-84 Takeoff distance Landing distance Max Mach number Instantaneous turn rate Specific excess power Sustained load factor 600 rounds 20 mm ammunition 2,000 ft 2,000 ft M = 1.8 at optimum
