《那些古怪又讓人憂心的問題》第63期:氦氣球降落傘(2)
On landing, Walters was arrested, although the authorities had some trouble figuring out what to charge him with. At the time, an FAA safety inspector told the New York Times, “We know he broke some part of the Federal Aviation Act, and as soon as we decide which part it is, some type of charge will be filed.”
A relatively small helium balloon-certainly smaller than a parachute-will suffice to slow your fall, but it still has to be huge by party balloon standards. The biggest consumer rental helium tanks are about 250 cubic feet, and you would need to empty at least ten of them to put enough air in the balloon to support your weight.
一個相對較小的氦氣球（當然比降落傘要小）能夠使你的下落速度降到足夠低，但它和派對上用的氣球相比還是要大很多的。目前最大的可租用的民用氦氣箱的容積大約在7立方米左右，而你至少需要10個這樣的儲氣箱才能填滿能夠載着你飛起來的氣球。You'd have to do it quickly. Compressed helium cylinders are smooth and often quite heavy, which means they have a high terminal velocity. You'll have only a few minutes to use up all the cylinders. (As soon as you emptied one, you could drop it.)
你的動作必須得非常迅速。壓縮氦氣罐一般來說外表光滑，而且非常沉重，這意味着它的下落終端速度非常高。你只有幾分鐘的時間來把氣球充滿。（你可以用完一個扔一個……）
You can't get around this problem by moving your starting point higher. As we learned from the steak incident, since the upper atmosphere is pretty thin, anything dropped from the stratosphere or higher will accelerate to very high speeds until it hits the lower atmosphere, then fall slowly the rest of the way. This is true of everything from small meteors1 to Felix Baumgartner.
你沒法通過增加下落高度來爭取更多的時間。因爲正如我們在牛排那一篇學到的，上層大氣層非常稀薄，任何從平流層以上掉下來的東西都會加速到極高的速度，直到它衝入下層大氣層之後，速度纔會降下來。小到隕石1，大到菲利克斯•鮑姆加特納都是如此。But if you inflated the balloons quickly, possibly by connecting many canisters to it at once, you'd be able to slow your fall. Just don't use too much helium, or you'll end up floating at 16,000 feet like Larry Walters.
但如果你能很快把氣球充滿（比如把好幾個氣罐同時連到氣球上），那麼還是能降低下落速度的。但記得別用太多的氦氣，不然你就要像拉里•沃爾特斯那樣無助地飄在5000米高空了。While researching this answer, I managed to lock up my copy of Mathematica several times on balloon-related differential equations, and subsequently got my IP address banned from Wolfram|Alpha for making too many requests. The ban-appeal form asked me to explain what task I was performing that necessitated so many queries. I wrote, “Calculating how many rental helium tanks you'd have to carry with you in order to inflate a balloon large enough to act as a parachute and slow your fall from a jet aircraft.”
在查資料寫這篇文章的時候，我的Mathematica被那些和氣球有關的微分方程鎖住了好幾次，接下來我的IP還被Wolfram Alpha3給屏蔽了，因爲它說我請求次數太多了。解除屏蔽的申請表要求我解釋我在搗鼓什麼纔會產生這麼多次請求，而我是這麼寫的：“計算從飛機上跳下來時需要帶多少個氦氣罐才能充滿一個足夠大的氣球，使它能起到降落傘的作用，降低下落速度。”Sorry, Wolfram.
對不住啦，Wolfram。
