《那些古怪又让人忧心的问题》第63期:氦气球降落伞(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.
一个相对较小的氦气球（当然比降落伞要小）能够使你的下落速度降到足够低，但它和派对上用的气球相比还是要大很多的。目前最大的可租用的民用氦气箱的容积大约在7立方米左右，而你至少需要10个这样的储气箱才能填满能够载着你飞起来的气球。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.)
你的动作必须得非常迅速。压缩氦气罐一般来说外表光滑，而且非常沉重，这意味着它的下落终端速度非常高。你只有几分钟的时间来把气球充满。（你可以用完一个扔一个……）
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.
你没法通过增加下落高度来争取更多的时间。因为正如我们在牛排那一篇学到的，上层大气层非常稀薄，任何从平流层以上掉下来的东西都会加速到极高的速度，直到它冲入下层大气层之后，速度才会降下来。小到陨石1，大到菲利克斯•鲍姆加特纳都是如此。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.
但如果你能很快把气球充满（比如把好几个气罐同时连到气球上），那么还是能降低下落速度的。但记得别用太多的氦气，不然你就要像拉里•沃尔特斯那样无助地飘在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.”
在查资料写这篇文章的时候，我的Mathematica被那些和气球有关的微分方程锁住了好几次，接下来我的IP还被Wolfram Alpha3给屏蔽了，因为它说我请求次数太多了。解除屏蔽的申请表要求我解释我在捣鼓什么才会产生这么多次请求，而我是这么写的：“计算从飞机上跳下来时需要带多少个氦气罐才能充满一个足够大的气球，使它能起到降落伞的作用，降低下落速度。”Sorry, Wolfram.
对不住啦，Wolfram。
