《那些古怪又讓人憂心的問題》第53期:星級塞斯納(2)
In particular, if you change the X-Plane config file to reduce gravity, thin the atmosphere, and shrink the radius of the planet, it can simulate flight on Mars.
X-Plane tells us that flight on Mars is difficult, but not impossible. NASA knows this, and has considered surveying Mars by airplane. The tricky thing is that with so little atmosphere, to get any lift, you have to go fast. You need to approach Mach 1 just to get off the ground, and once you get moving, you have so much inertia that it's hard to change course-if you turn, your plane rotates, but keeps moving in the original direction. The X-Plane author compared piloting Martian aircraft to flying a supersonic ocean liner.
X-Plane告訴我們在火星上駕駛飛機可不容易，但也不是不可能。NASA知道這一點，所以他們考慮用飛機來巡視火星。但問題在於，在如此稀薄的大氣環境下要想獲得足夠的升力，就需要很高的速度。你需要達到近1馬赫的速度才能起飛，而一旦你動了起來，巨大的慣性使你難以轉彎——如果你嘗試轉彎，那麼飛機會翻滾，同時繼續保持原有航向。所以X-Plane的作者把駕駛火星飛機比作駕駛超音速遊輪。Our Cessna 172 wouldn't be up to the challenge. If launched from 1 km, it wouldn't build up enough speed to pull out of a dive, and would plow into the Martian terrain at over 60 m/s (135 mph). If dropped from 4 or 5 kilometers, it could gain enough speed to pull up into a glide-at over half the speed of sound. The landing would not be survivable.
我們的塞斯納172可完不成這種任務。如果它從1千米的高度釋放，它將無法積累足夠的速度以擺脫俯衝狀態，並將以每秒60米（每小時216千米）的速度墜毀在火星表面。不過如果從4～5千米的高度釋放，飛機能夠達到足夠的速度以脫離俯衝而進入滑翔狀態——此時空速超過音速的一半。在這種情況下想要活着降落是不可能的。
Venus: Unfortunately, X-Plane is not capable of simulating the hellish environment near the surface of Venus. But physics calculations give us an idea of what flight there would be like. The upshot is: Your plane would fly pretty well, except it would be on fire the whole time, and then it would stop flying, and then stop being a plane.
金星：不幸的是，X-Plane無法模擬金星近表面那地獄式的環境。但是簡單的物理計算能告訴我們一些東西。結局是這樣的：你的飛機能飛得很順暢，只不過它一直處於着火狀態，然後它就飛不動了，再然後它就不是飛機了。The atmosphere on Venus is over 60 times denser than Earth's. It's thick enough that a Cessna moving at jogging speed would rise into the air. Unfortunately, that air is hot enough to melt lead. The paint would start melting off in seconds, the plane's components would fail rapidly, and the plane would glide gently into the ground as it came apart under the heat stress.
金星上的大氣密度是地球上的60多倍，在這種條件下一架塞斯納足以以人類跑步速度起飛。不幸的是，空氣溫度足夠把鉛熔化，飛機上的油漆在幾秒內就會熔化，飛機的部件也會迅速失效，再之後在熱應力的作用下飛機會解體，然後在空中慢慢飄落。A much better bet would be to fly above the clouds. While Venus's surface is awful, its upper atmosphere is surprisingly Earthlike. At 55 kilometers, a human could survive with an oxygen mask and a protective wetsuit; the air is room temperature and the pressure is similar to that on Earth mountains. You would need the wetsuit, though, to protect you from the sulfuric acid.
一個更好的選擇是在雲層上方飛行。雖然金星的表面糟透了，但是它的上層大氣層與地球驚人地相似。在距離地面55千米的地方，一個人戴着氧氣面罩，身着密閉防護服就能活下來，氣溫跟室溫差不多，氣壓也跟地球上的山脈上相近。你需要穿着防護服是因爲大氣裏有硫酸。
