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Why Are Airplane Windows Round?

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While some passengers might be too terrified—or sedated—to notice, frequent travelers may sometimes wonder why the windows that line airplane rows are round. Windows in the home are rectangular; car partitions are angled, but mostly rectangular. Why don’t planes follow suit?

It’s actually not an aesthetic choice. Airplanes used to have square windows. And they wound up crashing because of them.

When commercial airlines graduated to faster and larger jets beginning in the 1950s, planes would sometimes essentially disintegrate midair. Two of them, both de Havilland Comets, fell apart within months of one another in 1954 and killed a total of 56 passengers. Investigators traced the flaw to the squared-off corners of windows, which collect the stress of a pressurized cabin and can be prone to fracture. During one test, the Royal Aircraft Establishment found that up to 70 percent of the airplane’s stress was concentrated on the window's sharp angles.

Circular windows, which are able to disperse that pressure more evenly, immediately became the new standard in passenger aviation. And for every one you see, there are actually three panes at work: one bears the burden of pressurization, another inner pane acts as a failsafe in case the outer pane fails—which is rare—and one “scratcher” pane faces the occupant, so that you can smudge and dirty it up to your heart’s content.

As for that little hole at the bottom: It’s there to make sure the working pane takes the brunt of the air pressure, maintaining the emergency pane for, well, emergencies.

Mystery solved.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Food
United Airlines Has Gotten Rid of Tomato Juice, and Customers Are Freaking Out
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Lovers of tomato juice are a small camp, but a vocal one. And they're furious that United Airlines has replaced their beloved Mott's tomato juice with Mr. and Mrs. T Bloody Mary Mix on all flights under four hours, which includes most of its domestic runs. United said these changes are part of efforts to “streamline” its food service, the Chicago Business Journal reports.

The stealth substitution has fueled a rebellion among loyal tomato juice fans, as The Week points out.

There is some truth to the claim that tomato juice tastes better on flights. One study revealed that the noise level on an airplane affects our perception of taste, making savory or umami flavors more delicious. Another industry-funded study said the air pressure and humidity levels make bolder drinks seem more appealing.

Premium and economy passengers flying United can also say goodbye to Sprite Zero, Jim Beam, Courvoisier, and Amaretto, which were cut from the menu. And although airlines are not exactly known for their cuisine to begin with, passengers will likely start to see a difference in the types of meals being offered. The Chicago Business Journal writes:

"The reduction in food being offered in many instances in first-class and business-class cabins is not insignificant. Hot breakfasts are being replaced on some routes with only fruit plates and muffins, and more substantial lunches are being switched out for wraps and chocolate slabs."

The airline has said it is "monitoring customer feedback."

[h/t The Week]

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Live Smarter
This Travel Site Factors in Baggage Fees to Show You the True Cost of Your Flight
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If you're looking to find the best deal on airfare, there are more tools out there to help you than ever before. Travel sites allow users to compare ticket prices based on airlines and the dates of their trip, but the numbers they show don't always paint the full picture. Additional fees for baggage can make a flight that seemed like a steal at booking suddenly a lot less convenient. Fortunately for frugal flyers, KAYAK has found a way to work this factor into their equations, Travel + Leisure reports.

To use the fare search engine's new baggage fee feature, start by entering the information for your flight like you normally would. Flying from New York to Chicago and back the first week of May? KAYAK recommends taking Spirit Airlines if you're looking to pay as little as possible.

But let's say you plan on checking two bags on your flight—different airlines charge different baggage fees, so Spirit may no longer be the cheapest option. If that's the case, KAYAK includes a Fee Assistant bar right above the search results. After entering the number of carry-on and checked bags you'll be traveling with, the results will automatically update to show the true cost of your fare. Ticket prices for New York to Chicago rise across the board with the addition of two checked bags, and Delta now becomes the best deal if you're looking to book through one airline.

The new baggage fee assistant is one way for travelers to make savvier purchases when booking online. But even with the added fees included, you'll need to do some extra research to determine the true value you get from each ticket price that pops up. Wi-Fi, legroom, and in-flight meal quality are all factors that could make a slightly more expensive airline worth it once you board.

[h/t Travel + Leisure]

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