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Tham khảo tài liệu 'kỹ thuật máy bay chiến đấu episode 2 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 336 AIRCRAFT DESIGN Table 14.2 Typical limit load factors positive negative General aviation normal 2.5 to 3.8 -1 to -1.5 General aviation utility 4.4 -1.8 General aviation aerobatic 6 -3 Homebuilt 5 2 Transport 3 to 4 - 1 to - 2 Strategic bomber 3 -1 Tactical bomber 4 -2 Fighter 6.5 to 9 -3 to -6 designed their Flyer to a 5-g limit load. This remains a reasonable limit load factor for many types of aircraft. Table 14.2 lists typical limit load factors. Note that the required negative load factors are usually much less in magnitude than the positive values. The V-n diagram depicts the aircraft limit load factor as a function of airspeed. The V-n diagram of Fig. 14.3 is typical for a general aviation aircraft. Note that the maximum lift load factor equals 1.0 at level-flight stall speed as would be expected. The aircraft can be stalled at a higher speed by trying to exceed the available load factor such as in a steep turn. The point labeled high A.O.A. angle of attack is the slowest speed at which the maximum load factor can be reached without stalling. This part of the flight envelope is important because the load on the wing is approximately perpendicular to the flight direction not the body-axis vertical direction. BUFFET GUST NEGATIVE MANEUVER AILERON ROLL POSITIVE DYNAMIC GUST YAW MANEUVER AND LATERAL GUST LATERAL MANEUVER TAXI NEGATIVE GUST LANDING POSITIVE TAXI JACKING MANEUVER AND TOWING POSITIVE MANEUVER AND STATIC GUST NEGATIVE MANEUVER AND BRAKING POSITIVE DYNAMIC GUST AND LATERAL GUST Fig. 14.2 Lion critical loads. STRUCTURES AND LOADS 337 At high angle of attack the load direction may actually be forward of the aircraft body-axis vertical direction causing a forward load component on the wing structure Fig. 14.4 . During World War I several aircraft had a problem with the wings shedding forward due to this unexpected load. Fig. 14.3 V-n diagram manuever . Fig. 14.4 Wing load direction at angle of attack. 338 AIRCRAFT DESIGN The aircraft maximum speed or
