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[27飞行操纵] 关于舵面配平的5W1H:Aircraft Trim Explained (With Pictures)

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发表于 2022-2-1 08:35:49 | 显示全部楼层 |阅读模式 来自: 中国北京


00

译者的话


有大概…… 一只手那么多的读者想探讨关于飞行中配平操作的话题。这给了我很大的动力去啃飞行手册和系统资料,我准备好了一个5W1H的写作提纲,但是,在动笔之前我看到了这样一篇既讲使用、也讲设计的好文章。它让我想到了“飞机是设计来飞的”,我决定先推荐这篇给读者。




Pilots often have a lot to do when flying and aircraft trim helps pilots manage that workload and keep the aircraft moving in the right direction. It can be a pilot’s best friend! So what is aircraft trim? 

飞行员很忙,而飞机配平帮助他们减轻工作负载,保持飞行的正确方向。它是飞行员的好朋友,那么什么是飞机配平?

Aircraft trim holds control surfaces (rudder, elevator, or ailerons) in a specific position, requiring less manual input from the pilot to maintain a desired flight attitude. Trim either moves entire control surfaces (like on a stabilator) or is installed as a separate trim tab (like on an elevator).

飞机配平,把舵面(方向舵、升降舵,副翼)保持在特定位置,从而在减少飞行员输入的情况下,也可以维持飞行姿态。配平,有可能是移动舵面,或者是分离的配平调整片(例如在升降舵上)。

One of the biggest benefits of using trim is the reduction of pilot workload, both physically and mentally. Part of being a safe and proficient pilot is understanding what trim is, how it works, and how to use it. 

使用配平的最大好处之一,是减少飞行员的工作负载,体力和精力两个方面。要成为一个安全而专业的飞行员,就要理解配平是什么?它如何起作用?以及如何使用它?



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01

What is aircraft trim?


‍‍‍‍‍‍‍‍‍‍‍‍‍‍什么是飞机配平?

Aircraft trim is an adjustment to the control surfaces

飞机配平是舵面的一种调整。

Better said, we can replace the word trim with “adjust” and get a similar meaning. 

我们可以用“调整”来替代“配平”这个词,意思是相似的。

When we “trim” an aircraft, we are adjusting one or more of the movable control surfaces so that the pilot doesn’t need to hold them with physical strength and can focus elsewhere. 

当我们“配平”一架飞机,我们调整一个或多个的可移动舵面,于是飞行员不需要用体力去保持他们,可以关注其他事情。

Aircraft trim can be controlled directly by the pilot to adjust inflight operation of the trim devices by using mechanical means such as an elevator or rudder trim wheel, by a servo motor actuated by the pilot through an electrical switch such as with aircraft that use “powered trim” or indirectly by the pilot through the autopilot which would then also use servo motors to control the trim functions. 

飞机配平有不同的实现方式:可以由飞行员直接使用机械方式,比如升降舵或方向舵配平手轮;或者飞行员通过电控电门、借助伺服马达来实现;或者由自动驾驶系统,同样借助伺服马达来实现。【注解:这段话的原文很艰涩,这里已经整理。再进一步梳理就是:手动配平、电动配平、自动驾驶配平。B737的小伙伴应该有感觉吧?】

Trim Wheels Cessna 182 (塞斯纳 182 的配平手轮)‍‍‍‍‍‍‍‍‍‍


There are many different types of aircraft trim and they all share the same purpose of keeping the aircraft on the intended flight path flying predictably, efficiently, and safely and with limited pilot interaction.

飞机配平有许多不同的类型,目的相同,都是把飞机保持在预定的飞行轨迹上,安全而高效,不需要过多的飞行员操作。



02

Why is trim used on aircraft?


为什么要用配平?

Aircraft trim is useful to reduce the effort required to keep a movable control surface in any given position at a certain and specific airspeed by deflecting the air moving around it.

用来减少负担。

Aircraft trim can and must be adjusted during the flight as conditions warrant.

在飞行中,当条件许可,飞机配平可以并且也必须被调整。

Correctly applied trim helps reduce control pressures that would normally be felt by the pilot (or servo) typically by a need to constantly push or pull the yoke or stick constantly to maintain pitch and altitude, having to apply and maintain foot pressure to the rudder to control yaw or to apply and maintain aileron deflection to maintain a wings level bank. 

正确地使用配平,可以减少飞行员(或伺服装置)所感受到的控制压力,典型的比如:持续地推杆或拉杆来保持俯仰姿态、把脚保持在踏板来控制偏航、保持副翼偏转来保持滚转角。这些都是使用配平的场景。

Without the proper use of trim, holding and maintaining control surfaces manually can lead to physical and mental pilot fatigue, pilot distraction from other duties, inconsistent control surface deflection leading to an erratic flight path and premature or accelerated wear on the control surface linkage to the cockpit such as the wire ropes (often called cables), pulleys, pins and bearings which can lead to increased maintenance and inspection costs and reduced service life of the impacted components.

如果没有正确使用配平,而是过多地使用人力,将会导致飞行员体力和精力上的疲劳、导致飞行员无法专注于其他任务。不协调的舵面偏转量,将导致错误的飞行轨迹和部件的提前老化、维修成本的上升。


03

Elevator trim


升降舵配平

The most common trim is elevator trim which we can find in many aircraft regardless of age, manufacturer or type of aircraft.  

最常见的配平是升降舵配平,可以在很多飞机上看到,无论哪个年代、制造商和机型。

The elevator is a control surface on the tail that raises or lowers the nose of the aircraft. 

升降舵是尾部的舵面,用于抬起或降下飞机的机头。

Elevator trim helps reduce the amount of control pressure needed to keep the elevator in a certain position.

升降舵配平帮助减少用于将方向舵保持在特定位置上的控制压力。


How Elevator Trim Works

升降舵配平如何起作用?

The elevator trim is usually a small separate part of the elevator (called a “trim tab”) that helps the pilot move the elevator to the required position and keep it there.

通常使用一个分离的部分,叫做“调整片”。

For aircraft equipped with stabilators, the trim actually moves the entire stabilator and is not a separate trim tab.

对于安装了 stabilator 的飞机,配平实际上是移动整个舵面,而不是分离的调整片。【注解:这个词不好翻译,它的前半截和 stabilizer 长得很像,后半截…… 没错,它其实就是stabilizer 和 elevator 的合体,怎么翻译呢?“整体式平尾”?很多战斗机用这种。】

Elevator trim is actuated typically by a trim control wheel in the cockpit, or it can also be electrically driven (usually via a switch on the pilot’s yoke), or automatically by servos controlled by an autopilot.

升降舵的典型控制方式是,通过驾驶舱里的一个配平手轮,或者也可以被电动驱动(通常是通过驾驶盘上的一个电门),或者由自动驾驶系统通过伺服装置来自动控制。

What is interesting (and counterintuitive) about how elevator trim works is that the trim tab actually creates opposite deflection to the direction of the elevator. 

关于升降度配平,比较有意思(或者说违反直觉)的是:配平调整片实际上是在和升降舵相反的方向上产生偏转。

To point the aircraft nose upward, this would require upward deflection of the elevator that pushes the tail down and the nose up. To accomplish this through trim, the trim tab would actually have downward deflection to push the elevator upward.

为了让机头向上,就需要升降舵向上偏转,从而把尾部压下去、把机头抬起。为了通过配平来完整这个,调整片实际上是向下偏转从而推动升降舵向上!

Here is an image with the trim fully deflected in the “nose up” position (note that the elevator was held level just to more clearly show what the trim tab is doing… in actual flight this would cause the elevator to deflect upward).

这里有个图片,配平完全偏转到机头向上位,注意:图片里的升降舵还处于水平状态,这样可以更清楚地展示调整片的动作,而在实际飞行中,调整片的这动作会导致升降舵向上偏转。


The trim tab here is shown deflecting a small amount of passing air downward so that reciprocal effect (while flying) will be for the trim tab to push the rear of the elevator up, pushing the tail down and the nose up.

这里的调整片偏转了下方经过空气的很小部分,就产生了反向的效应,推动升降舵的后缘向上,使机尾向下、机头向上。

The opposite happens with nose down trim, pictured below.

机头向下的配平,如下图所示。

Note that while flying, this upward deflection of the trim tab would cause the elevator to deflect downward, thus pushing the tail up and the nose down.

注意:在飞行中,调整片的这种向上偏转,会导致方向舵向下偏转,从而推动机尾向上、机头向下。


When to Use Elevator Trim

什么时候使用升降舵配平?

Elevator trim can be used as much as needed to relieve the amount of control pressure needed to keep the elevator in a certain position. Elevator trim is put to work during climbs, cruise, and descents/landings alike. 

可以尽可能多地使用,从而减少控制压力。升降舵配平用于爬升、巡航和下降、着落。


Elevator Trim at Takeoff 

起飞阶段的升降舵配平

Aircraft will typically have a desired elevator trim setting for takeoff. This will be listed in the Pilot’s Operating Handbook (POH) and is also sometimes visually presented on the trim wheel itself, or digitally in some glass instruments.

这会在飞行操作手册上有说明。配平量可能会在配平手轮上显示,也可能会是数字形式的显示。

This is a critical pre-takeoff checklist item to make sure your elevator trim is properly set! 

确保正确设置了升降舵配平量,这是一个关键的起飞前检查单项目!

Also be sure to use the manufacturer’s checklist to test electric trims before takeoff. You may find that the electric trim simply doesn’t work, or you may find that once it starts moving, it doesn’t stop. This is called runaway trim and if this happens in flight it can be a difficult situation. 

同样也要使用制造商的检查单来测试电动配平。有时候可能会发现电动配平不工作;或者一旦工作就停不下来了,这叫做“配平失控”,如果在空中发生了,形势会很困难。


Elevator Trim in the Climb

爬升阶段的升降舵配平

A climb typically begins when the pilot pulls back on the yoke and deflects the elevator upward, pushing the tail downward and raising the nose of the aircraft.

典型的爬升开始于向后拉杆,这样使升降舵向上偏转。

Two things can quickly happen during the climb: the pilot’s arm gets tired from pulling on the yoke, and he also gets distracted. 

两件事很快发生了:飞行员的手臂变得疲劳、精力分散了。

Applying nose-up trim (see image above) takes the place of the pilot physically applying back pressure to the elevator.

使用抬头配平,替代飞行员施加在升降舵上的体力。

It reduces the physical workload on the pilot but also reduces mental workload. With the airplane now climbing on its own, the pilot is also mentally freed up to focus on other pertinent tasks. 

这减少了体力负载,但同样也减少了精力负载。当飞机自己爬升,飞行员的精力就可以用于其他相关任务。

Elevator trim will need to be adjusted periodically during the climb.

在爬升阶段,升降舵配平可能会需要周期性的调整。

When the climb first begins, the airplane has more inertia from straight and level flight, and does not need significant elevator input for the climb because there is more air flowing over the control surfaces. 

爬升刚开始,飞机有更多的直接向前的惯性,并且不需要太多的升降舵输入,因为此时流过舵面的空气比较多。

As the aircraft climbs and slows, more elevator deflection (and thus trim) will be required to maintain the climb.

当飞机继续爬升并减速,就需要更多的升降舵偏转(从而也需要更多的配平)来保持爬升。

As the aircraft enters less dense air with higher altitude, more trim may be required to maintain the climb as well. 

当飞机进入了密度更小的空气、更高的高度,就需要更多的配平量来保持爬升。

But overall, elevator trim can help the airplane to nearly climb on its own with little input from the pilot. It’s like having another set of hands or a copilot onboard! 

但是总体上,升降舵配平帮助飞机基本上“靠自己”来爬升,飞行员只需要很少的输入。它就像是有了另一双手或者多了一位副驾驶。【注解:副驾驶的地位……】


Elevator Trim in Cruise

巡航阶段的升降舵配平

Elevator trim is extremely useful during the cruise phase of the flight to maintain level altitude without the pilot needing to touch the yoke.

在巡航阶段,升降舵配平非常有用,可以使飞机保持水平姿态,而不需要飞行员去触碰驾驶杆。

Aircraft equipped with electrim trim and an autopilot might autotrim the aircraft to reduce servo pressures on the control surfaces.

有电动配平和自动驾驶系统的飞机,能自动配平飞机,从而减少舵面上的伺服压力。

Some autopilots (like the STEC-30) will notify the pilot that more manual upward or downward elevator trim is required to reduce servo input, but will not actually adjust the trim automatically. 

一些自动驾驶系统(比如STEC-30)会提示飞行员需要更多的人工向上或向下的升降舵配平来减少伺服输入,但不会实际去自动调整配平。

As cruise continues, the pilot might need to slightly retrim the aircraft to compensate for weight and balance changes due to fuel burn. 

当巡航继续,由于燃油消耗导致了飞机重量和平衡的改变,飞行员可能会需要稍微重新做一下配平。


Elevator Trim in Descent/Landing

下降/着陆阶段的升降舵配平

Trimming the aircraft during descent is similar to climb. The pilot can set a desired descent rate and appropriate power setting and the appropriately trimmed aircraft will fly itself during the descent.

在下降阶段配平,与在爬升时相似,飞行员可以设置需要的下降率和适当的功率,配平得比较好的飞机会自己飞……

Possibly the most helpful use of trim is during the landing phase of the flight.

可能配平最有用的阶段就是着陆了!

It is a common technique to use pitch (using elevator trim) to achieve a certain airspeed, and use power/throttle adjustments to control altitude and descent rate. That technique can be seen and elaborated upon in this video:

一般的技术是使用俯仰(使用升降舵配平)来获得特定的空速,使用功率/油门调整来控制姿态和下降率。下面是视频。【注解:原文缺失视频,以后找到了补上……】



04

Rudder Trim


方向舵配平

Rudder trim is quite common on general aviation aircraft. 

在通航飞机上,方向舵配平很常见。

The rudder is a control surface usually mounted at the rear edge of the vertical stabilizer that swings left and right pushing the tail left and right thereby moving the nose of the aircraft left and right. 

方向舵是安装在垂直安定面后缘的舵面,向左或向右推动机尾,从而使机头向右或向左。

The rudder is controlled by foot pedals at the pilot’s feet, pushing the right pedal moves the nose to the right and pushing the left pedal moves the nose to the left.

方向舵通过飞行员脚下的脚蹬来控制,踩下右侧脚蹬,使机头向右;踩下左侧脚蹬,使机头向左。

Rudder trim helps reduce the amount of control pressure needed to keep the rudder in a certain position. 

方向舵配平减轻了用于保持方向舵位置的控制压力。


How Rudder Trim Works

方向舵配平是如何起作用的?

Rudder trim is very similar to elevator trim, just applied on a different axis. Often the rudder will have a rudder trim tab (pictured below) that creates opposite air deflection to the rudder and pushes it in the desired direction. 

方向舵配平和升降舵配平很相似,只是参考轴不一样了。方向舵往往会有一个方向舵配平调整片(看图),产生与方向舵相反的偏转,把方向舵推向所需要的方向。


Many small aircraft will have the rudder trim incorporated into the entire rudder, meaning that an adjustment in trim slightly changes the direction of the entire rudder itself, instead of through a trim tab. The Cessna 182 is an example of this. 

很多小飞机会有融入于整个方向舵的配平,意思是,一个很小的调整,会改变整个方向舵的方向,而不是通过一个小的调整片。Cessna 182 就是一个例子。【注解:原文还是有点绕。简单讲,就是没有调整片,但是仍然有配平。】

Permanent Rudder Trim

永久性的方向舵配平

Some aircraft designers build in a permanent anti-torque rudder trim tab to reduce the pilot and rudder trim workload at all speeds

一些飞机设计师搞出了一种永久性的“反力矩方向舵配平调整片”,来减少所有速度下的飞行员和方向舵配平工作量。


This permanent and fixed trim device is usually mounted at the far rear of the aircraft on the rudder itself and is bent to a specific shape and in a direction that benefits the overall aircraft design with no pilot input required. 

这种永久且固定的配平装置,通常安装在飞机的最末端,在方向舵上,被弯成特定的形状。

In the case above, the permanent tab is mounted at the base of the rudder and is pointed such that the passing air will push the trim tab to the right, thereby pushing the rudder to which it is firmly attached to the right and replacing some of the right rudder the pilot would otherwise need to apply with a foot or through the rudder trim control.

在上面的例子中,永久性调整片安装在方向舵的基座上,流过的空气会推动调整片向右,从而推动方向舵向右,从而替代原本由飞行员通过脚蹬或方向舵配平控制部件来施加的一部分输入。


When to Use Rudder Trim

什么时候使用方向舵配平?

Rudder trim is mostly used during climbs, descents, and possibly emergency scenarios of twin engine aircraft. 

方向舵配平,大多适用于爬升、下降阶段,以及可能用于双发飞机的一些紧急场景。


Rudder Trim During Climb

爬升阶段的方向舵配平

Due to p-factor (the asymmetric thrust generated by a propeller where one side of the propeller is taking a bigger “bite” of air than the other due to the pitch of the aircraft), single engine piston aircraft have a left turning tendency during climb.

由于飞机的俯仰姿态,螺旋桨一侧产生的推力大于另一侧,这叫做 p-factor【注解:翻译成“俯仰效应”如何?下面的图片是另外找到的配图】。在爬升阶段,单发活塞飞机有一种向左转弯的趋势。


Applying right rudder trim can help alleviate a tired right foot constantly pushing on the right rudder pedal during this phase of flight.

这阶段,施加在方向舵上的向右配平,可以帮助缓解持续施加在右侧脚蹬上的压力。


Rudder Trim During Descents

下降阶段的方向舵配平

Due to p-factor, single engine piston aircraft have a left yaw tendency during descents (the opposite of climbs), and left rudder trim can be applied to correct this. 

同样由于“俯仰效应”,单发活塞飞机有一种机身向左偏航(向右转弯)的趋势,这与爬升时相反,此时,方向舵向左配平可以纠正这个趋势。


Rudder Trim in Engine Loss

双发飞机单发之后的方向舵配平

When flying twin engine aircraft, the loss of one engine will create heavy yaw in the direction of the lost engine due to asymmetric thrust. In addition to heavy rudder application, rudder trim can help alleviate some of the pressure required to keep the airplane coordinated, though additional rudder pressure from the pilot will likely still be required. 

对于双发飞机,损失一台发动机之后,由于推力不对称,会产生严重的偏航,这时候就需要方向舵的重度使用。作为补充,配平可以帮助缓解一些控制压力,尽管飞行员仍需要施加比平常更多的压力。



05

Aileron Trim


副翼配平

Ailerons control the roll of the aircraft. Knowing how trim works on the elevator and the rudder, let’s take a look at the aileron trim. 

副翼控制横滚。前面介绍了安定面和方向舵配平的原理,再来看看副翼配平。


How Aileron Trim Works

副翼配平是怎么工作的?


For airplanes equipped with aileron trim, the ailerons sometimes have an aileron trim tab (pictured below) that creates opposite air deflection to the aileron and pushes it in the desired direction. 


有的飞机会有调整片(如图所示)【注解:B737有,A320没有】,产生和副翼相反的空气偏转,将副翼推向所需的方向。

For some aircraft like the Cirrus SR22, aileron trim will actually just move the entire aileron (similar to trim on a stabilator or some rudders) and do not have trim tabs. 

有些飞机,比如 Cirrus SR22,副翼配平会实际上会移动整个副翼,它们没有调整片。(这与前面提过的 stabilator 以及 一些方向舵很像吧)

Because the two main wings are actually one wing, if one wing rises and the other must fall. For this reason you may see aileron trim tabs on only one aileron or sometimes they will be on both if the aircraft was designed that way. Even in single installations, the aileron trim still affects both wings simultaneously.

由于是被固定的,两个大翼实际上等于是一个大翼,一侧抬起则另一侧低下。由于这样的原因,你可能看到有些飞机只有一侧的副翼有,有的两侧都有,这是设计使然。但是即使只有一侧有,副翼调整的效果仍然会同时作用到两侧大翼上。


When to Use Aileron Trim

什么时候使用副翼配平?

Aileron trim can be used whenever the aircraft will not maintain straight flight. Sometimes airplanes can develop slight roll tendencies to one side or the other for a number of reasons (minor dents, stretching and re-rigging of the control surface cables, change of onboard equipment) and will require slight but perpetual aileron trim to correct it. 

只要飞机不能维持直飞,就可以使用副翼配平。有时候由于一些原因,比如小的凹坑、舵面钢索被过量拉伸或经过校装、机载设备的改变,飞机可能会积累出轻微的滚转趋势,这时候需要轻微但是持续的配平来纠正这个趋势。

The larger need for aileron trim comes from the weight and balance of the aircraft (passenger, crew, and fuel loading and configuration). The need for aileron trim could also change during the course of the flight as fuel is burned off and the weight and balance of the aircraft changes. 

副翼配平的更重要运用,是源于在乘客、机组、燃油和构型造成的载重和平衡的变化。副翼配平量的需求,由于燃油的消耗,同样也会在整个飞行阶段发生变化。



06

How to Properly Use Trim


如何正确使用配平

A safe and accurate way to trim an aircraft (elevator, rudder, or aileron) is to achieve the desired flight attitude with the yoke (or stick) and then slowly trim the aircraft until the yoke pressure is no longer needed to maintain the same attitude.

安全而准确的配平方法,是先通过驾驶杆(或侧杆)获得需要的飞行姿态,然后缓慢地配平,直到不再需要驾驶杆压力,就可以维护同样的姿态。

In other words, set the airplane in the desired attitude and then use trim to hold the airplane in that attitude where your input is no longer required. 

换句话说,把飞机设置在所需的姿态上,然后再用配平来保持在一个不再需要输入的姿态上。【注解:也就是说实际姿态和最初计划的理论上的理想姿态是略有不同的!】

It is important to not use the trim adjustment wheel, crank handle or other device to force the airplane to fly as you want.

重要的是:不要使用配平调整手轮、手柄或者其他设备来强行让飞机按你所想的那样来飞。

Critically, the order of application for all movable trims such as this is to use the pilots own effort to get the aircraft in the correct yaw, pitch and bank attitude, then use the trim to relieve the trim pressures required, checking and adjusting always in this same order.

关键点:所有可移动配平的顺序,都是首先使用飞行员自身的力量来让飞机获得正确的偏航、俯仰和横滚姿态,然后再使用配平来缓解配平压力。检查和调整配平时,总是这样的顺序。

Always consult the POH for guidance on trim usage in your aircraft. 

务必遵守你的机型操作手册来使用配平。



07

Final Thought


最后的思考

The proficient and consistent use of aircraft trim is a useful and often necessary tool for all pilots, and especially for those pilots who fly at night, in heavy traffic areas such as Class C or B airspaces or in IMC where pilot workloads can quickly become overwhelming

熟练和持续地使用飞机配平对所有飞行员来说都是有用的、经常是必要的工具,特别是那些在夜间飞行的飞行员,在交通繁忙的地区,如C类或B类空域,或在飞行员工作负载会快速变得不堪重负的仪表气象条件。

Aircraft trim is designed to ease that workload while also adding to the efficient, safe and fun operation of your aircraft.

飞机配平,被设计来减轻工作负荷,同时也让飞行操作变得高效、安全和有趣。


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