Section I Activity mode and main points of coaching

航空模型活动一般包括制作、放飞和比赛三种方式，也可据此划分为三个阶段：

Aviation model activities generally include production, release and competition, which can also be divided into three stages:

制作活动的任务是完成模型制作和装配。通过制作活动对学生进行劳动观点、劳动习惯和劳动技能的教育。使他们学会使用工具，识别材料、掌握加工过程和得到动手能力的训练。

The task of the production activity is to complete the model production and assembly. Through production activities, students will be educated about labor ideas, labor habits and labor skills. Make them learn to use tools, identify materials, master the processing process and get hands-on training.

放飞是学生更加喜爱的活动，成功的放飞，可以大大提高他们的兴趣。放飞活动要精心辅导，要遵循放飞的程序，要介绍飞行调整的知识，要有示范和实际飞行情况的讲评。通过放飞对学生进行应用知识和身体素质的训练。

Flying is a favorite activity for students. Successful flying can greatly improve their interest. The release activities should be carefully guided, follow the release procedures, introduce the knowledge of flight adjustment, and have demonstration and actual flight situation evaluation. The students are trained in applied knowledge and physical quality through flying.

比赛可以把活动推向高潮，优胜者受到鼓舞，信心十足：失利者或得到教训，或不服输也会憋足劲头。是引导学生总结经验，激发创造性和不断进取精神的好形式。参加大型比赛将使他们得到极大的锻炼而终生不忘。

The competition can bring the event to a climax, and the winners are encouraged and confident: the losers will either learn a lesson or not admit defeat, and will also hold their strength. It is a good way to guide students to sum up experience, stimulate creativity and keep forging ahead. Participating in large-scale competitions will give them great exercise and never forget it.

第二节 飞行调整的基础知识

Section II Basic knowledge of flight adjustment

飞行调整是飞行原理的应用。没有起码的飞行原理知识，就很难调好飞好模型。辅导员要引导学生学习航空知识，并根据其接受能力、结合制作和放飞的需要介绍有关基础知识。同时也要防止把航模活动变成专门的理论课。

Flight adjustment is the application of flight principle. Without basic knowledge of flight principles, it is difficult to adjust the flight model well. The instructor should guide students to learn aviation knowledge and introduce relevant basic knowledge according to their acceptance ability and the needs of production and release. At the same time, it is also necessary to prevent aircraft model activities from becoming specialized theoretical courses.

一、升力和阻力

1、 Lift and drag

飞机和模型飞机之所以能飞起来，是因为机翼的升力克服了重力。机翼的升力是机翼上下空气压力差形成的。当模型在空中飞行时，机翼上表面的空气流速加快，压强减小;机翼下表面的空气流速减慢压强加大(伯努利定律)。这是造成机翼上下压力差的原因。

The reason why aircraft and model aircraft can fly is that the lift of wings overcomes gravity. The lift of the wing is formed by the pressure difference between the upper and lower air of the wing. When the model is flying in the air, the air velocity on the upper surface of the wing increases and the pressure decreases; The air velocity on the lower surface of the wing slows down and the pressure increases (Bernoulli's law). This is the cause of the pressure difference between the upper and lower wings.

造成机翼上下流速变化的原因有两个：a、不对称的翼型;b、机翼和相对气流有迎角。翼型是机翼剖面的形状。机翼剖面多为不对称形，如下弧平直上弧向上弯曲(平凸型)和上下弧都向上弯曲(凹凸型)。对称翼型则必须有一定的迎角才产生升力。

There are two reasons for the change of the flow velocity of the wing: a. asymmetric airfoil; B. The wing and relative air flow have an angle of attack. An airfoil is the shape of an airfoil section. The wing profile is mostly asymmetrical, and the following arcs are straight and upward curved (flat and convex), and the upper and lower arcs are upward curved (concave and convex). Symmetrical airfoils must have a certain angle of attack to generate lift.

升力的大小主要取决于四个因素：a、升力与机翼面积成正比;b、升力和飞机速度的平方成正比。同样条件下，飞行速度越快升力越大;c、升力与翼型有关，通常不对称翼型机翼的升力较大;d、升力与迎角有关，小迎角时升力(系数)随迎角直线增长，到一定界限后迎角增大升力反而急速减小，这个分界叫临界迎角。

The lift is mainly determined by four factors: a. The lift is proportional to the wing area; B. The lift is proportional to the square of the aircraft speed. Under the same conditions, the faster the flight speed, the greater the lift; C. The lift is related to the airfoil. Generally, the lift of asymmetric airfoil wings is large; D. The lift is related to the angle of attack. At a small angle of attack, the lift (coefficient) increases linearly with the angle of attack. When the angle of attack increases, the lift decreases rapidly. This boundary is called the critical angle of attack.

机翼和水平尾翼除产生升力外也产生阻力，其他部件一般只产生阻力。

The wing and horizontal tail generate drag in addition to lift, and other components generally only generate drag.

二、平飞

2、 Level flight

水平匀速直线飞行叫平飞。平飞是基本的飞行姿态。维持平飞的条件是：升力等于重力，拉力等于阻力。

Horizontal uniform straight flight is called level flight. Level flight is the basic flight attitude. The conditions for maintaining level flight are that lift equals gravity and pull equals drag.

由于升力、阻力都和飞行速度有关，一架原来平飞中的模型如果增大了马力，拉力就会大于阻力使飞行速度加快。飞行速度加快后，升力随之增大，升力大于重力模型将逐渐爬升。为了使模型在较大马力和飞行速度下仍保持平飞，就必须相应减小迎角。反之，为了使模型在较小马力和速度条件下维持平飞，就必须相应的加大迎角。所以操纵(调整)模型到平飞状态，实质上是发动机马力和飞行迎角的正确匹配。

Since the lift and drag are related to the flight speed, if the horsepower of a model in the original level flight is increased, the pull will be greater than the drag to speed up the flight speed. As the flight speed increases, the lift will increase, and the model with lift greater than gravity will gradually climb. In order to maintain the level flight of the model at higher horsepower and flight speed, the angle of attack must be reduced accordingly. On the contrary, in order to maintain the level flight of the model under the condition of small horsepower and speed, the angle of attack must be correspondingly increased. So controlling (adjusting) the model to level flight is essentially the correct match between engine horsepower and flight angle of attack.

三、爬升

3、 Climb

前面提到模型平飞时如加大马力就转为爬升的情况。爬升轨迹与水平面形成的夹角叫爬升角。一定马力在一定爬升角条件下可能达到新的力平衡，模型进入稳定爬升状态(速度和爬角都保持不变)。稳定爬升的具体条件是：拉力等于阻力加重力向后的分力(F=X十Gsinθ);升力等于重力的另一分力(Y=GCosθ)。爬升时一部分重力由拉力负担，所以需要较大的拉力，升力的负担反而减少了。和平飞相似，为了保持一定爬升角条件下的稳定爬升，也需要马力和迎角的恰当匹配。打破了这种匹配将不能保持稳定爬升。例如马力增大将引起速度增大，升力增大，使爬升角增大。如马力太大，将使爬升角不断增大，模型沿弧形轨迹爬升，这就是常见的拉翻现象。

As mentioned earlier, when the model is in level flight, if it increases the horsepower, it will change to climbing. The included angle between the climb path and the horizontal plane is called the climb angle. A certain horsepower may reach a new force balance under a certain climbing angle, and the model enters a stable climbing state (both speed and climbing angle remain unchanged). The specific condition for stable climbing is that the pulling force is equal to the backward component of resistance plus gravity (F=X X Gsin θ); Lift equals another component of gravity (Y=GCos θ)。 When climbing, part of the gravity is borne by the pull force, so it needs a larger pull force, and the lifting force burden is reduced. Similar to peace flight, in order to maintain a stable climb at a certain angle of climb, the proper matching of horsepower and angle of attack is also required. Breaking this match will not maintain stable climbing. For example, an increase in horsepower will cause an increase in speed, lift and climb angle. If the horsepower is too high, the climbing angle will increase continuously, and the model will climb along the arc path, which is a common phenomenon of pull-over.

四、滑翔

4、 Glide

滑翔是没有动力的飞行。滑翔时，模型的阻力由重力的分力平衡，所以滑翔只能沿斜线向下飞行。滑翔轨迹与水平面的夹角叫滑翔角。

Gliding is flight without power. When gliding, the resistance of the model is balanced by the component of gravity, so gliding can only fly downward along the oblique line. The angle between the glide path and the horizontal plane is called the glide angle.

稳定滑翔(滑翔角、滑翔速度均保持不变)的条件是：阻力等于重力的向前分力(X=GSinθ);升力等于重力的另一分力(Y=GCosθ)。

The condition for stable glide (glide angle and glide speed remain unchanged) is that the resistance is equal to the forward component of gravity (X=GSin θ); Lift equals another component of gravity (Y=GCos θ)。

滑翔角是滑翔性能的重要方面。滑翔角越小，在同一高度的滑翔距离越远。滑翔距离(L)与下降高度(h)的比值叫滑翔比(k)，滑翔比等于滑翔角的余切滑翔比，等于模型升力与阻力之比(升阻比)。Ctgθ=1/h=k。

Gliding angle is an important aspect of gliding performance. The smaller the gliding angle, the farther the gliding distance at the same height. The ratio of the glide distance (L) to the descent height (h) is called the glide ratio (k). The glide ratio is equal to the cotangent glide ratio of the glide angle, and is equal to the ratio of the lift to the drag of the model (lift-drag ratio). Ctg θ= 1/h=k。

滑翔速度是滑翔性能的另一个重要方面。模型升力系数越大，滑翔速度越小;模型翼载荷越大，滑翔速度越大。

Gliding speed is another important aspect of gliding performance. The higher the lift coefficient of the model, the smaller the glide speed; The greater the model wing load, the greater the glide speed.

调整某一架模型飞机时，主要用升降调整片和前后移动来改变机翼迎角以达到改变滑翔状态的目的。

When adjusting a certain model aircraft, the wing angle of attack is mainly changed by using the lifting adjustment piece and the center of gravity moving forward and backward to achieve the purpose of changing the glide state.

五、力矩平衡和调整手段

5、 Torque balance and adjustment means

调整模型不但要注意力的平衡，同时还要注意力矩的平衡。力矩是力的转动作用。模型飞机在空中的转动是自身的，所以重力对模型不产生转动力矩。其它的力只要不通，就对产生力矩。为了便于对模型转动进行分析，把绕的转动分解为绕三根假想轴的转动，这三根轴互相垂直并交于。贯穿模型前后的叫纵轴，绕纵轴的转动就是模型的滚转;贯穿模型上下的叫立轴，绕立轴的转动是模型的方向偏转;贯穿模型左右的叫横轴，绕横轴的转动是模型的俯仰。

Adjusting the model requires not only the balance of attention, but also the balance of torque. Moment is the rotational action of force. The rotation center of the model aircraft in the air is its own center of gravity, so gravity does not produce rotation torque on the model. As long as other forces do not reach the center of gravity, they will produce torque to the center of gravity. In order to facilitate the analysis of model rotation, the rotation around the center of gravity is decomposed into rotation around three imaginary axes, which are perpendicular to each other and intersect at the center of gravity. The longitudinal axis runs through the front and back of the model, and the rotation around the longitudinal axis is the rolling of the model; The vertical axis runs through the top and bottom of the model, and the rotation around the vertical axis is the direction deflection of the model; The horizontal axis runs through the left and right of the model, and the rotation around the horizontal axis is the pitch of the model.

对于调整模型来说，主要涉及四种力矩;这就是机翼的升力力矩，水平尾翼的升力力矩;发动机的拉力力矩;动力系统的反作用力矩。

For the adjustment model, it mainly involves four kinds of moments; This is the lift moment of the wing, the lift moment of the horizontal tail; Tensile torque of engine; Reaction torque of power system.

机翼升力力矩与俯仰平衡有关。决定机翼升力矩的主要因素有纵向位置、机翼安装角、机翼面积。

The wing lift moment is related to the pitch balance. The main factors that determine the wing lift moment are the longitudinal position of the center of gravity, the wing installation angle, and the wing area.

水平尾翼升力力矩也是俯仰力矩，它的大小取决于尾力臂、水平尾翼安装角和面积。

The lift moment of the horizontal tail is also the pitching moment, and its size depends on the installation angle and area of the tail arm and the horizontal tail.

拉力线如果不通过就会形成俯仰力矩或方向力矩，拉力力矩的大小决定于拉力和拉力线偏离距离的大小。发动机反作用力矩是横侧(滚转)力矩，它的方向和螺旋桨旋转方向相反，它的大小与动力和螺旋桨质量有关。

If the tension line does not pass through the center of gravity, it will form pitching moment or directional moment. The magnitude of the tension moment depends on the magnitude of the distance between the tension line and the center of gravity. The reaction torque of the engine is the lateral (rolling) torque, its direction is opposite to the rotation direction of the propeller, and its magnitude is related to the power and the mass of the propeller.

俯仰力矩平衡决定机翼的迎角：增大抬头力矩或减小低头力矩将增大迎角;反之将减小迎角。所以俯仰力矩平衡的调整为重要。一般用升降调整片、调整机翼或水平尾翼安装角、改变拉力上下倾角、前后移动未实现。

The angle of attack of the wing is determined by the balance of the pitching moment: the angle of attack will be increased by increasing the heading moment or decreasing the bow moment; Otherwise, the angle of attack will be reduced. Therefore, the adjustment of pitch moment balance is very important. Generally, it is not achieved by adjusting the installation angle of the wing or horizontal tail, changing the pull up and down inclination, and moving the center of gravity forward and backward.