Introduction to Aviation Theory 航空理论简介
There were a number of problems that students would have encountered when building the “unbalanced mini glider”. The design of this miniature glider was intentionally flawed and would have required a number of minor adjustments to improve the overall strength and flight ability of this model plane. The aim of the “unbalanced mini glider” assignment was not to create a perfect plane. Instead the main aim of this project was to introduce students to several key concepts, including the idea of balance, structural integrity, materials, and how scale models do not always provide an accurate reflection of what we would expect in the real world.
学生们在建造“失衡微型滑翔机”时会遇到了许多问题。此设计是有意留有缺陷，进而需要做一些小的调整，以提高这架模型飞机的整体强度和飞行能力。“失衡迷你滑翔机”任务的目的不是创造一架完美的飞机，而是向学生介绍几个关键概念，包括平衡、结构完整性、材料，以及比例模型如何不能准确反映实物等。
Review 复习
What was wrong with the “unbalanced mini glider”?
之前的失衡迷你滑翔机设计有什么问题？
Although the overall portions of this model plane reflect the actual portions of a real plane, there are a number of discrepancies that have resulted from using different materials. These differences in-turn resulted in a number of issues that would have become obvious during test. Firstly, the plane would not have flown straight. Instead the front of the plane would have swooped upwards, while the tail section would start dragging downwards until the plane stalled in midair. At this point the plane would no longer be able to produce lift and it would crash to the ground tail first. Upon impact the fuselage would have likely snapped in two where the body of the plane meets the tail and horizontal stabilizer.
尽管此模型飞机的整体部分尽可能贴合了真实飞机，但由于材质的不同也会产生许多差异，这些差异就会导致了一些问题，在试飞中就能明显看到这些问题所在。首先，飞机不会直线飞行，飞机的前部会向上俯冲，而尾部会开始向下拖动，直到飞机在半空中失速，此时，飞机将不再能够产生升力，尾部将首先撞击地面。撞击时，机身很可能会在机身与尾部和水平稳定器相接的地方裂成两半。
The reason for this is that the tail of the plane is much heavier than it should be, based on the limitations that were introduced by the model materials.
这是因为飞机的尾部比它应该承受的重量要重得多，归根于制作模型的材料。
The shape of the wings, stabilizer, and tail in this simple model are rectangular (shown by a red line) based on the foam board construction of this model; however, in real life a plane would have an airfoil that has a very different shape (shown with a green line). The difference between the two shapes results in the model aircraft having a volume that is almost double what it should be in certain locations. This results in the tail of the plane being much heavier than it should be which affected the overall balance of the plane. And this is why the plane would have crashed tail first.
基于泡沫板结构，该模型中机翼、稳定器和尾部的形状为矩形（如图红线显示）；然而，在现实生活中，飞机的翼型是不同的形状（如图绿线显示）。这两种形状之间的差异导致模型飞机的体积在某些位置几乎要重两倍。这意味着飞机尾部比其应有的重量大得多，从而影响了飞机的整体平衡，也就是为什么飞机会先坠毁尾部。
The issue of balance is also greatly exaggerated based on the position of the excess weight relative to the plane’s centre. If you think about mechanical forces in physics, a simple machine such as a lever can be used to reduce the amount of work needed to lift an object. Based on the distribution of weigh relative to its distance from the fulcrum (centre of balance) a larger mass can be moved with less effort. The same thing is happening with the plane but in revers. As the tail of the plane is much further away from the planes centre of balance than the nose is, any differential of weight gets amplified significantly.There is also one more factor that has thrown the mini glider off balance! Can you think about what that issue is based on the following photograph?
由于离飞机中心的位置较远，多余重量导致的平衡问题也就加大了许多。如物理学中的机械力，一个简单的杠杆可以大大减少提升物体所需的工作量。根据重量相对于支点（平衡中心）距离的分布，可以轻松移动较大的质量。此理论也适用于飞机上，但情况相反。由于飞机尾部比机头离飞机平衡中心远得多，因此任何重量差都会明显放大。还有一个因素使迷你滑翔机失去平衡，你能根据下面的照片找到答案吗？
In the actual plane there would be space for a pilot, possibly a co-pilot, and all of the planes navigation equipment. All these things would add a lot of weight to the plane which is not accounted for in the design of the mini-glider. This lack of weight at the front of the plane further amplifies the issue of the tail section of the plane which is already over weight.
实际的飞机上会有飞行员甚至副飞行员的空间，以及所有的飞机导航设备。这些都会给飞机增加很多重量，但在迷你滑翔机的设计中是没有考虑的。飞机前部重量不足进一步加剧了飞机尾部已经超重的问题。
Mini Glider Conclusion & Summary 微型滑翔机结论和总结
Simply changing the scale of an object to make a scaled model does not always work out. For instance, the density, strength, and weight of the materials that you use to build your scale model airplane will not be the same as the materials that were used to build the original airplane. This results in balance or structural issues that need to be resolved in-order for your model airplane to fly properly.
仅仅改变一个物体的比例来制作一个比例模型并不总是有效的，例如，用于建造比例模型飞机的材料的密度、强度和重量将与用于建造真实飞机的材料不同，这会导致平衡或结构问题。为了使你的模型飞机能正常飞行，你需要解决这些问题。
Introduction to Aviation Theory 航空理论简介
Look at each plane for 10 seconds and think about the following. 观察各飞机10秒然后回答下列问题。
- What is the function / purpose of the airplane?
此飞机的功能/目的是什么？ - What is the shape of this airplane’s wing?
此飞机的机翼是什么形状？ - Why do you think the engineers designed each airplane the way they did?
为什么设计师进行这样的设计？
Common Wing Designs 常见机翼设计
As you can see from this slide show, there are numerous types of wing designed used in the aviation industry. Each design has its own unique advantages and disadvantages, so it is important for engineers to determine the specific needs of the plane that they are designing, analyze any constrains, and make informed decisions. However, despite the seemingly infinite number of designs that you may encounter when studying aviation theory, each design falls into of 10 different categories.
正如下面幻灯片所示，在航空业中有许多类型的机翼，每种设计都有其独特的优点和缺点。因此工程师需要确定他们所设计的飞机的具体需求、分析任何约束条件并做出正确的决策。然而，尽管在学习航空理论时可能会遇到无数种设计，但每种设计都可以归类到下列10个类别中。
Side Profiles 侧面轮廓
The side profile of a wing shows the shape of the airfoil. Depending on the design of the airfoil the plane may be capable of either sub-sonic or supersonic flight. It is important that the correct airfoil is selected based on intend use of the plane. For instance, sub-sonic designs create a significant amount of lift at low speeds but the wing would be ripped appear at higher speeds. This is very different from a supersonic wing design which is much smaller and stronger. These planes fly based on the pure force of thrust that is created by incredibly powerful engines. Essentially the plane cuts through the air like a knife instead of gently gliding through it.
机翼的侧面轮廓显示了机翼的形状。根据机翼的设计，飞机可以进行亚音速或超音速飞行。根据飞机的用途选择正确的翼型是很重要的。例如，亚音速设计在低速时产生很大的升力，但在高速时机翼会撕裂。这与超音速机翼设计非常不同，超音速机翼设计更小、更强。这类飞机的飞行完全依靠强大的发动机产生的推力。飞机像刀子一样在空中划过，而不是轻轻地滑过。
Top Profile 顶部轮廓
Finally, the top profile of the wing shows the overall shape of the wing when looking down on the plane from above. Again each design has its own unique advantages under certain circumstances.
最后，机翼的顶部轮廓显示了从上方俯视飞机时机翼的整体形状。同样，在特定情况下，每种设计都有其独特的优势。
As a seasoned aviation engineer the details of each of these designs is well known; however, as a student you probably don’t know much about any of these designs just yet. The first thing you should start doing is to think back to planes that you have seen in real life. Perhaps planes that you have flown on or have seen in person at an air show.
作为一名经验丰富的航空工程师，每个设计的细节都了如指掌；然而，作为一名学生，你可能还不太了解这些设计。那么，你现在要做的第一件事是回想你在现实生活中看到的飞机，可以是你曾经坐过的飞机，或者在航空展上亲眼见过的飞机。
Now think about each of the planes that you have seen. What did the wing look like? Can you describe what the front, side, and top view of the plane looked like based on the design samples that have been provided here? Now think about the purpose of that plane. Dose the plane fly at a modest speed or is it incredibly fast? Is the plane highly maneuverable or is it very stable? Is the plane capable of transporting heavy loads or is there only limited space for excess cargo?
回想你见过的飞机，他们的机翼是什么样子的？您能否根据上面提供的设计样例描述飞机的正面、侧面和俯视图？那架飞机的用途是什么？飞机是以适中的速度飞行还是以飞快的速度飞行？飞机是高度灵活还是非常稳定？飞机是否能够运输重物，或者空间有限？
Based on these initial observations can you come to any conclusions about what designs may be more suitable than others in a wide variety of scenarios? Now try to formulate a hypothesis which you could then build an experiment for with these observations.
通过这些初步观察，你是否可以得出一些结论关于在某些情况下，哪些设计可能比其他设计更适合。现在用这些观察结果试着提出一个实验假设。
Looking Forward 展望
In the next lesson you will be required to make a number of observations of planes that you have seen in the real world, analyze the function of these planes, and then determine why the engineers designed these planes with particular choices. You will then evaluate the merits of different design choices and create a design for a wing design that you would like to build and test.
在下节课中，你要对现实世界中看到的飞机进行更多的观察，分析其功能，并确定为什么工程师在设计时进行这样特定的设计。然后，评估不同设计的优点，并设计你自己想要创建和测试的机翼类型。
