tailieunhanh - Aircraft Design: Synthesis and Analysis - part 9

yengine là khoảng cách từ đường tâm thân máy bay T động cơ chính là lực đẩy cất cánh cho động cơ chính lv là chiều dài đuôi thẳng đứng (khoảng cách từ cg dọc đuôi ac) tăng kéo tổng số là tổng của thời hạn windmilling và cắtkéo. Những độ dốc leo lên được xác định cho tất cả các trọng lượng áp dụng, độ cao, và nhiệt độ. | Yengine is the distance from fuselage centerline to critical engine T is the take-off thrust for the critical engine lv is the vertical tail length distance from . to vertical tail . The total drag increment is the sum of the windmilling term and the trim drag. These climb gradients are determined for all applicable weights altitudes and temperatures. From this data the maximum permissible weight for a given condition are established. Operational Climb Normal climb to cruise altitude is carried out at the speed for best overall economy high speed climb which is considerably faster than the speed for maximum rate of climb which in turn is much faster than the speed for maximum climb gradient. If fuel quantity is limiting climb may be performed at the speed for best fuel economy long range climb speed a speed between the best overall economy climb speed and the best gradient climb speed. Speed schedules are selected to be easily followed by the pilot with available instrumentation. Recent introduction of automatic flight directors makes this task easier. The computed climb rates are integrated to produce time fuel and distance to climb to any altitude. For approximate calculations the additional fuel to climb to altitude as compared with cruising the same distance at the cruise altitude can be approximated by adding an increment to the total cruise fuel. This increment has been determined for a wide range of weights for the DC-9-30 the DC-8-62 and the DC-10-10. The results expressed as a percentage of take-off weight are summarized in the following figure. For different aircraft such as SST s we might think more fundamentally about the cause of this fuel increment. With a rough estimate of the overall propulsion efficiency we can express the extra fuel used in terms of the change in kinetic and potential energy. The net result expressed as a percentage of takeoff weight is Wclimb_fuel_inc Wto h kft V kts 844 2 This agrees with the plot above indicating a .