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.
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.
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.
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.
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.4
The acid’s no fun, but it turns out the area right above the clouds is a great environment for an airplane, as long as it has no exposed metal to be corroded away by the sulfuric acid. And is capable of flight in constant category-5-hurricane-level winds, which are another thing I forgot to mention earlier.
Venus is a terrible place.
Jupiter: Our Cessna wouldn’t be able to fly on Jupiter; the gravity is just too strong. The power needed to maintain level flight under Jupiter’s gravity is three times greater than that on Earth. Starting from a friendly sea-level pressure, we’d accelerate through the tumbling winds into a 275 m/s (600 mph) downward glide deeper and deeper through the layers of ammonia ice and water ice until we and the aircraft were crushed. There’s no surface to hit; Jupiter transitions smoothly from gas to liquid as you sink deeper and deeper.
Saturn: The picture here is a little friendlier than on Jupiter. The weaker gravity—close to Earth’s, actually—and slightly denser (but still thin) atmosphere mean that we’d be able to struggle along a bit further before we gave in to either the cold or high winds and descended to the same fate as on Jupiter.
Uranus: Uranus is a strange, uniform bluish orb. There are high winds and it’s bitterly cold. It’s the friendliest of the gas giants to our Cessna, and you could probably fly for a little while. But given that it seems to be an almost completely featureless planet, why would you want to?
Neptune: If you’re going to fly around one of the ice giants, I would probably recommend Neptune5 over Uranus. It at least has some clouds to look at before you freeze to death or break apart from the turbulence.
Titan: We’ve saved the best for last. When it comes to flying, Titan might be better than Earth. Its atmosphere is thick but its gravity is light, giving it a surface pressure only 50 percent higher than Earth’s with air four times as dense. Its gravity—lower than that of the Moon—means that flying is easy. Our Cessna could get into the air under pedal power.
In fact, humans on Titan could fly by muscle power. A human in a hang glider could comfortably take off and cruise around powered by oversized swim-flipper boots—or even take off by flapping artificial wings. The power requirements are minimal—it would probably take no more effort than walking.
The downside (there’s always a downside) is the cold. It’s 72 kelvin on Titan, which is about the temperature of liquid nitrogen. Judging from some numbers on heating requirements for light aircraft, I estimate that the cabin of a Cessna on Titan would probably cool by about 2 degrees per minute.
The batteries would help to keep themselves warm for a little while, but eventually the craft would run out of heat and crash. The Huygens probe, which descended with batteries nearly drained, taking fascinating pictures as it fell, succumbed to the cold after only a few hours on the surface. It had enough time to send back a single photo after landing—the only one we have from the surface of a body beyond Mars.
If humans put on artificial wings to fly, we might become Titanian versions of the Icarus story—our wings could freeze, fall apart, and send us tumbling to our deaths.
But I’ve never seen the Icarus story as a lesson about the limitations of humans. I see it as a lesson about the limitations of wax as an adhesive. The cold of Titan is just an engineering problem. With the right refitting, and the right heat sources, a Cessna 172 could fly on Titan—and so could we.
1The Cessna 172 Skyhawk, probably the most common plane in the world.
2Also, our gasoline is MADE of ancient plants.
3Who uses capslock a lot when talking about planes.
4I’m not selling this well, am I?
5Motto: “The Slightly Bluer One.”
weird (and worrying) questions from the what if? INBOX, #6
Q. What is the total nutritional value (calories, fat, vitamins, minerals, etc.) of the average human body?—Justin Risner
Q. What temperature would a chainsaw (or other cutting implement) need to be at to instantly cauterize any injuries inflicted with it?
—Sylvia Gallagher
Yoda
Q. How much Force power can Yoda output?
—Ryan Finnie
A. I’m going to—of course—ignore the prequels.
Yoda’s greatest display of raw power in the original trilogy came when he lifted Luke’s X-wing from the swamp. As far as physically moving objects around goes, this was easily the biggest expenditure of energy through the Force we saw from anyone in the trilogy.
The energy it takes to lift an object to a given height is equal to the object’s mass times the force of gravity times the height it’s lifted. The X-wing scene lets us use this to put a lower limit on Yoda’s peak power output.
First we need to know how heavy the ship was. The X-wing’s mass has never been canonically established, but its length has—12.5 meters. An F-22 is 19 meters long and weighs 19,700 kg, so scaling down from this gives an estimate for the X-wing of about 12,000 pounds (5 metric tons).
Next, we need to know how fast it was rising. I went over footage of the scene and timed the X-wing’s rate of ascent as it was emerging from the water.
The front landing strut rises out of the water in about three and a half seconds, and I estimated the strut to be 1.4 meters long (based on a scene in A New Hope where a crew member squeezes past it), which tells us the X-wing was rising at 0.39 m/s.
Lastly, we need to know the strength of gravity on Dagobah. Here, I figure I’m stuck, because while sci-fi fans are obsessive, it’s not like there’s gonna be a catalog of minor geophysical characteristics for every planet visited in Star Wars. Right?
Nope. I’ve underestimated the fandom. Wookieepeedia has just such a catalog, and informs us that the surface gravity on Dagobah is 0.9g. Combining this with the X-wing mass and lift rate gives us our peak power output:
That’s enough to power a block of suburban homes. It’s also equal to about 25 horsepower, which is ab
out the power of the motor in the electric-model Smart Car.
At current electricity prices, Yoda would be worth about $2/hour.
But telekinesis is just one type of Force power. What about that lightning the Emperor used to zap Luke? The physical nature of it is never made clear, but Tesla coils that produce similar displays draw something like 10 kilowatts—which would put the Emperor roughly on par with Yoda. (Those Tesla coils typically use lots of very short pulses. If the Emperor is sustaining a continuous arc, as in an arc welder, the power could easily be in the megawatts.)
What about Luke? I examined the scene where he used his nascent Force powers to yank his lightsaber out of the snow. The numbers are harder to estimate here, but I went through frame-by-frame and came up with an estimate of 400 watts for his peak output. This is a fraction of Yoda’s 19kW, and was sustained for only a fraction of a second.
So Yoda sounds like our best bet as an energy source. But with world electricity consumption pushing 2 terawatts, it would take a hundred million Yodas to meet our demands. All things considered, switching to Yoda power probably isn’t worth the trouble—though it would definitely be green.
Flyover States
Q. Which US state is actually flown over the most?
—Jesse Ruderman
A. When people say “flyover states,” they’re usually referring to the big, square states out west that people stereotypically cross over while flying between New York, LA, and Chicago, but don’t actually land in.
But what state do the largest number of planes actually fly over? There are a lot of flights up and down the East Coast; it would be easy to imagine that people fly over New York more often than Wyoming.
To figure out what the real flyover states are, I looked at over 10,000 air traffic routes, determining which states each flight passed over.
Surprisingly, the state with the most planes flying over it—without taking off or landing—is . . .
. . . Virginia.
This result surprised me. I grew up in Virginia, and I certainly never thought of it as a “flyover state.”
It’s surprising because Virginia has several major airports; two of the airports serving DC are actually located in Virginia (DCA/Reagan and IAD/Dulles). This means most flights to DC don’t count toward flights over Virginia, since those flights land in Virginia.
Here’s a map of US states colored by number of daily flyovers:
Close behind Virginia are Maryland, North Carolina, and Pennsylvania. These states have substantially more daily flyovers than any other.
So why Virginia?
There are a number of factors, but one of the biggest is Hartsfield-Jackson Atlanta International Airport.
Atlanta’s airport is the busiest in the world, with more passengers and flights than Tokyo, London, Beijing, Chicago, or Los Angeles. It’s the main hub airport for Delta Air Lines—until recently the world’s largest airline—which means passengers taking Delta flights will often connect through Atlanta.
Thanks to the large volume of flights from Atlanta to the northeast US, 20 percent of all Atlanta flights cross Virginia and 25 percent cross North Carolina, contributing substantially to the totals for each state.
However, Atlanta isn’t the biggest contributor to Virginia’s totals. The airport with the most flights over Virginia was a surprise to me.
Toronto Pearson International Airport (YYZ) seems an unlikely source of Virginia-crossing flights, but Canada’s largest airport contributes more flights over Virginia than New York’s JFK and LaGuardia airports combined.
Part of the reason for Toronto’s dominance is that it has many direct flights to the Caribbean and South America, which cross US airspace on the way to their destinations.1 In addition to Virginia, Toronto is also the chief source of flights over West Virginia, Pennsylvania, and New York.
This map shows, for each state, which airport is the source of the most flights over it:
Flyover states by ratio
Another possible definition of “flyover state” is the state that has the highest ratio of flights over it to flights to it. By this measure, the flyover states are, for the most part, simply the least dense states. The top ten include, predictably, Wyoming, Alaska, Montana, Idaho, and the Daktoas.
The state with the highest ratio of flights-over-to-flights-to, however, is a surprise: Delaware.
A little digging turned up the very straightforward reason: Delaware has no airports.
Now, that’s not quite true. Delaware has a number of airfields, including Dover Air Force Base (DOV) and New Castle Airport (ILG). New Castle Airport is the only one that might qualify as a commercial airport, but after Skybus Airlines shut down in 2008, the airport had no airlines serving it.2
Least flown-over state
The least flown-over state is Hawaii, which makes sense. It consists of tiny islands in the middle of the world’s biggest ocean; you have to try pretty hard to hit it.
Of the 49 non-island states,3 the least flown-over state is California. This came as a surprise to me, since California is long and skinny, and it seems like a lot of flights over the Pacific would need to pass over it.
However, since jet-fuel-laden planes were used as weapons on 9/11, the FAA has tried to limit the number of unnecessarily fuel-heavy flights crossing the US, so most international travelers who might otherwise travel over California instead take a connecting flight from one of the airports there.
Fly-under states
Lastly, let’s answer a slightly stranger question: What is the most flown-under state? That is, what state has the most flights on the opposite side of the Earth pass directly under its territory?
The answer turns out to be Hawaii.
The reason such a tiny state wins in this category is that most of the US is opposite the Indian Ocean, which has very few commercial flights over it. Hawaii, on the other hand, is opposite Botswana in Central Africa. Africa doesn’t have a high volume of flights over it compared to most other continents, but it’s enough to win Hawaii the top spot.
Poor Virginia
As someone who grew up there, it’s hard for me to accept Virginia’s status as the most flown-over state. If nothing else, when I’m back home with family, I’ll try to remember—once in a while—to look up and wave.
(And if you find yourself on Arik Air Flight 104 from Johannesburg, South Africa to Lagos, Nigeria—daily service, departing at 9:35 a.m.—remember to look down and say “Aloha!”)
1It helps that Canada, unlike the US, has extensive commercial flight service to Cuba.
2This changed in 2013, when Frontier Airlines began operating a route between New Castle Airport and Fort Myers, Florida. This wasn’t included in my data set, and it’s possible Frontier will bump Delaware down the list.
3I’m including Rhode Island here, although it seems wrong to.
Falling with Helium
Q. What if I jumped out of an airplane with a couple of tanks of helium and one huge, un-inflated balloon? Then, while falling, I release the helium and fill the balloon. How long of a fall would I need in order for the balloon to slow me enough that I could land safely?
—Colin Rowe
A. As ridiculous as it sounds, this is—sort of—plausible.
Falling from great heights is dangerous.[citation needed ] A balloon could actually help save you, although a regular helium one from a party obviously won’t do the trick.
If the balloon is large enough, you don’t even need the helium. A balloon will act as a parachute, slowing your fall to nonfatal speeds.
Avoiding a high-speed landing is, unsurprisingly, the key to survival. As one medical paper put it . . .
It is, of course, obvious that speed, or height of fall, is not in itself injurious . . . but a h
igh rate of change of velocity, such as occurs after a 10 story fall onto concrete, is another matter.
. . . which is just a wordy version of the old saying “It’s not the fall that kills you, it’s the sudden stop at the end.”
To act as a parachute, a balloon filled with air—rather than helium—would have to be 10 to 20 meters across, far too big to be inflated with portable tanks. A powerful fan could be used to fill it with ambient air, but at that point, you may as well just use a parachute.
Helium
The helium makes things easier.
It doesn’t take too many helium balloons to lift a person. In 1982, Larry Walters flew across Los Angeles in a lawn chair lifted by weather balloons, eventually reaching several miles in altitude. After passing through LAX airspace, he descended by shooting some of the balloons with a pellet gun.
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.
What If? Page 11