飞机地面转弯力学行为研究

Mechanical behavior study of aircraft ground turning motion

大型飞机地面转弯时由于重量大、行驶速度低,所产生的道面侧推力极大。而现行道面设计规范,尤其是沥青混凝土道面设计规范,仅考虑竖向力作用而忽略转弯区侧向力,但机场跑道系统有很多弯道存在,因此这些部位的设计需考虑侧向力的作用。另外,操纵前轮转弯是目前民航客机地面转弯的主要方式,且飞机在地面转弯过程中受力复杂,侧风、道面平整度、驾驶员操纵方式和飞机速度等因素都会对其受力产生影响,为简化分析,设飞机在地面低速转弯过程中,前轮操纵角不变,某一瞬时做半径固定的匀速圆周运动。经过分析得到飞机所受侧向力和竖向力比值的简化公式,大大方便了侧向力的计算,并通过计算发现,飞机在转弯过程中各轮所受到的侧向力大小并不相等。对于B737-800机型,主起落架4个轮胎所受侧向力与竖向力的比值分别为1.33∶1.29∶1.04∶1,相对于转动中心,最外侧轮胎所受侧向力最大,最内侧轮胎所受侧向力最小,相差33%,因此在沥青道面转弯区设计中需考虑侧向力作用。

With the increasing size of civil aviation aimraft, the lateral thrust on the surface course is getting bigger and bigger because of the large weight and low speed when turning on the ground. The current pavement design specification, espeeially the asphalt concrete pavement design specification only considers the vertical force and ignores the lateral force, but the airport runway system has many corners, so it is neeessary to consider the lateral force during the design process of these parts. And the method of front wheel manipulation turning is the main mode of civil aircraft ground turning. Because the aircraft will he influeneed by complex forces in the ground turning process, which will be affected by the crosswind, pavement roughness, pilot control way and the plane speed and other factors, so in order to simplify the analysis, reasonable assumptions are made. It is considered that when the aircraft is in the low speed process of turning on the ground, the steering angle of the front wheel is constant. The instantaneous motion mode is circular motion whose radius is fixed. The simplified formula of the specific value of lateral and vertical force is obtained through analysis, which will make the lateral force caleulation mueh easier, and it is found that the lateral force of wheels is not equal in the process of turning. For the model B737-800, the ratio of lateral and vertical force of the four tires of main landing gear is 1.33 ： 1.29： 1.04：1, and the lateral force of the outermost tire relative to the center of rotation is the biggest. The lateral force of the innermost tire is the smallest, a drop of 33% than that of the outermost tire.