直升机飞行力学复习题答案

Chapter One

A helicopter of central articulated rotor makes a level flight with cruse speed. In this flight condition, the pitching attitude angle is 02ϑ=-, longitudinal cyclic pitching angle is 017

B =, rotor longitudinal flapping angle is 013s a =-. Assuming the tilted angle of rotor shaft is 00δ=, please determining the following angles:

Helicopter climb angle θ=

Fuselage attack angle α=

Rotor attack angle s α=

Rotor flapping due to forward speed 10a =

中心铰式旋翼直升机以巡航速度前飞。俯仰角-2°，纵向周期变距7°，纵向挥舞角-3°，旋翼轴前倾角0° 平飞，爬升角0°

机身迎角-2°

桨盘平面迎角-2°

吹风挥舞4°

Chapter Two

1.For the main/tail rotor configuration helicopter, the pilot applies

which stick or rudder to control what kind of surfaces and corresponding aerodynamic forces?

2.Why the gradient of control stick forces can’t be too large or small?

3.Co-axis, tandem and tilted-rotor helicopters have no tail rotor. How to

change the direction in hover for these helicopters?

1.操纵——气动面——响应P13表2-1

前推/后拉杆——纵向周期变距，桨盘前倾/后倒——前飞/后飞，俯仰左推/右推杆——横向周期变距，桨盘侧倒——侧飞，滚转

油门/总距杆——改变总距——改变垂向速度

脚蹬——改变尾桨总距——改变航向

2.为什么杆力梯度不能太大也不能太小P16

太大时大操纵较吃力，太小了不易感觉当前位移量。杆力梯度适中有利于精确操纵。

3.共轴、纵列、倾转旋翼机如何悬停转弯？

共轴——上下旋翼总距差动

纵列——前后横向周期变距一个向左一个向右

倾转旋翼——一侧后倒一侧前倒

Chapter Three

1.The rotation direction of Black hawk helicopter rotor is anticlockwise

from the top view. Please answer the following questions:

●How the rotor flaps when the helicopter comes up gust in hover?

How to adjust the controller to keep the hover condition?

●How the blade changes its feathering angle following the pilot’s

adjustment?

2.During left and right turn flights with constant speed and altitude, is

there any different for pilot controls?

3.Is there flapping motion for hinge-less rotor?

1.黑鹰直升机旋翼右旋

悬停时遇到阵风旋翼如何挥舞，此时如何操纵

前方来的阵风会导致旋翼后倒，右倒。应向前、向左推杆。

前推杆导致90°桨距变小，270°桨距变大

左推杆导致180°桨距变小，0°桨距变大

2.不改变高度和速度时，左转弯和右转弯有区别没？

以右旋直升机为例，左转时需要增加尾桨总距，为了平衡尾桨拉力的增加需要左推杆以增加侧向力，这却导致了旋翼拉力的降低，进而需要提总距，又导致向前拉力的增加，因而需要后拉杆。总之，右旋直升机前飞左转弯的操纵为，踩脚蹬—左压杆—提总距—后拉杆。

同理，右旋直升机右转弯的操纵为：松脚蹬—减小左压杆—减总距—减小前推杆3.无铰式旋翼有挥舞吗？

没有挥舞铰但是通过桨叶根部的柔性段或者桨榖柔性件的弹性变形实现挥舞运动。

Which items in the linear equations of helicopter motion reflect the longitudinal and lateral cross-coupling effect?

直升机线化运动方程中哪些项体现了横纵向的耦合P53

操纵输入系数矩阵C中，FX对横向周期变距A1、FZ对纵向周期变距B1的导数均不为0，即横向周期变距对后向力有影响，而纵向周期变距对侧向力也有影响。

1.What is the mission of helicopter trim calculation?

2.In order to keep the center of helicopter mass in the specified range it

is necessary to check the helicopter loadings before flight. Why the center of helicopter mass must be in the specified range?

3.The tail rotor of some helicopters is lower than main rotor. What is

the advantages and disadvantages when the tail rotor is lower than main rotor?

4.Bell-412 helicopter releases left and right buoys for making an urgent

lading on the water surface. Compare the differences of pilot controls and helicopter attitude before and after releasing buoys.

配平的任务是什么

根据平衡条件确定直升机稳定飞行所需的操纵量和直升机的姿态角。

为什么重心在特定的范围内

重心太前抑制直升机后飞及悬停低速性能，而太靠后则影响大速度前飞性能以及稳定性，因此重心需要限制在一定的范围内。

尾桨低于旋翼的好处及坏处P70

好处：尾梁扭转载荷不大，不需要加固垂尾以安装尾桨。总之可以减小结构重量。