You Cant Ignore Physics, Joe

by Jim Geraghty

National Review   April 8, 2021

On the menu today: Joe Biden urges America to pass his infrastructure bill so that one day trains can cross the United States as fast as jet planes do, a vision that does not align well with the laws of physics. The president also envisions passenger airliners flying ten times faster than the fastest spy plane in the air today. And we look ahead to the delayed Olympic games in Japan and the upcoming Winter games in Beijing.

Joe Biden’s Magic, Fast-as-a-Jet-Plane-Train Idea

Joe Biden is not all that different from Donald Trump in his propensity to just blurt out the first thing that pops into his mind, whether or not it’s true, whether or not it even sounds plausible, and whether or not what he’s describing violates the laws of physics.

Yesterday, in another sales pitch for his infrastructure plan, Biden said, “. . . what we’re really doing is raising the bar on what we can imagine. Imagine a world where you and your family can travel coast to coast, without a single tank of gas, or on a high-speed train close to as fast as you can go across the country in a plane.”

This is almost physically impossible, even if we make the most optimistic assessments about advances in rail technology. Commercial airliners usually travel 550 to 580 miles per hour.

A train that is being tested by Central Japan Railway Company hit a top speed of 374 miles per hour; it’s not yet in commercial use. When it is operational, the company plans for it to have a maximum operating speed of 310 mph. But right now, the “bullet trains” in Japan operate at about 200 miles per hour. (That’s about 40 to 50 miles per hour faster than Amtrak’s Acela trains.) France has a train that has hit a top speed of 357 miles per hour.

In other words, what Biden envisions, and implicitly is promising, is a train that goes across the continental U.S. at an average speed that is 47 percent faster than the top speed of the fastest prototype trains that exist today.

There are other complications. No matter how hard Biden tries, he cannot veto — and Congress cannot repeal — the laws of physics. Trains going extremely fast build up a lot of force — force equals mass times acceleration — and have to be extremely careful on curves. This 2013 New Yorker article explained it well:

One of those forces is centrifugal (“to flee from the center”) force, the inertia that makes a body on a curved path want to continue outward in a straight line. It’s what keeps passengers in their seats on a looping roller coaster and throws unsecured kids off carousels. Centrifugal force is a function of the square of the train’s velocity divided by the radius of the curve; the smaller and tighter the curve, or the faster the train, the greater the centrifugal force. As it increases, more and more of the weight of the train is transferred to the wheels on the outermost edge of the track, something even the best-built trains have trouble coping with. That’s where the concepts of minimum curve radius and super-elevation, or banking, come in.

To cope with centrifugal force, train tracks tilt on curves; the problem is that the train can only tilt so much before either it or the passengers inside tip over, so the curve must get larger and more gradual to safely carry a super-fast train. “Tracks rated for fifty miles per hour need almost no banking and can have a curve radius of fifteen hundred feet, while a train traveling at a hundred and twenty miles per hour needs a track with significant banking, and a minimum curve radius of more than a mile and a half.” A train track designed for a train going 550 miles per hour would have to have an absolutely gargantuan curve radius. Our current system and routes of train tracks would be completely unsafe for a train moving at that speed; it would fly off the tracks at the first curve.

And there are a few other problems. Higher speeds generally mean worse consequences for impacts, accidents, and derailments. Taiwan just had a terrible crash that killed at least 50 people, hitting a truck while the train was moving about 75 miles per hour. A Spanish train traveling 100 miles per hour derailed on a bend in 2013 and 79 people died, with another 140 injured. Now picture a train experiencing a collision or derailment while moving five times faster.

And if you’re thinking, “Hey, wouldn’t a train going 550 miles per hour make a tempting target for a terrorist,” you are correct. Worldwide, “between 1970 and the end of 2017, there were 282 attempts to deliberately derail trains and 817 additional attacks on railway infrastructure, including tracks, bridges, tunnels, signaling, and other right-of-way equipment. Of the 282 attempts to derail trains, 118 (or 42 percent) resulted in a derailment.”

Now, what makes this particular gaffe troubling is that we’ve been told, many times over, that Biden is a “rail enthusiast.” In fact, the Obama White House called Biden a “famed rail enthusiast.” But Biden appears to be the kind of rail enthusiast who doesn’t know or understand the first darn thing about trains.

It seems the president has never really thought about why we don’t have trains that travel as fast as planes already. It’s not that we can’t create powerful engines. You can throw a pair of enormous jet engines on a race-car chassis and get it to go 763 miles per hour — breaking the sound barrier and setting the land-speed record in the process. But that’s not going to work for passenger rail!

Yesterday, Biden continued, “We’re going to talk about commercial aircraft flying at subsonic speeds — supersonic speeds. To be able, figuratively, if you may, if we decide to do it, traverse the world in about an hour, travel 21,000 miles an hour. So much is changing, and we have got to lead it.”

The first part of this vision is relatively realistic. The old, retired Concorde plane had a maximum speed of 1,354 mph, more than twice the speed of sound. In fact, the Concorde was the second supersonic passenger airplane. The Soviet version of the Concorde, the Tupolev Tu-144, had a top speed of 1,600 miles per hour, and that sounds really appealing, as long as you can overlook the fact that 12.5 percent of all the Tu-144s ever built crashed.

The crash of a Concorde jet just outside the Paris Charles de Gaulle Airport in 2000 didn’t help, but what really forced the retirement of supersonic passenger jets was that it wasn’t cost-effective. The fuel costs would often exceed the revenue from the passengers — and flying on the Concorde was not cheap! — and supersonic flight over U.S. land is currently banned because the sonic booms can break windows. (By the way, a strong jet stream can add to a plane’s speed enormously; early last year, a British Airways Boeing 747 hit 825 miles per hour crossing the Atlantic.)

But Biden’s vision of a passenger aircraft that can “traverse the world in about an hour, travel 21,000 miles an hour” is a strong argument for mandatory drug testing in the White House. The fastest jet in the world is the SR-71 Blackbird, perhaps the most famous spy plane in the world, and it travels at 2,100 mph.

It is hard for us laymen to grasp the engineering challenges of designing something to fly that fast and keeping it functioning at that speed. My favorite anecdote about the SR-71 is that it was deliberately designed to leak fuel on the ground before takeoff:

However, there was one design feature that many presumed was a mechanical flaw. When the Blackbird took to the sky, its airframe started leaking, leaving a trail of jet fuel on the tarmac. While many were concerned that this would render the plane useless, the Blackbird was designed to eject its specialized fuel. When developing the aircraft, engineers accounted for the temperature fluctuations that it would experience. More specifically, they realized that the plane’s components would heat up as the aircraft gained more speed.

This friction would inevitably prompt the plane’s body to expand, so they had to fit some pieces together loosely. The fuselage panels, in particular, were purposely positioned farther apart. These loose-fitting parts are what produced the leakage, but it was a necessary design quality to prevent overexpansion. As the SR-71 reached 2,200 miles per hour, the panels enlarged as expected. Fortunately, there was enough room between them to allow for this inflation.

Biden is envisioning a commercial airliner that will travel ten times faster than the current fastest jet in the world. He might as well have promised warp speed, a hyperdrive, or teleportation. It goes well with his promise to cure cancer if elected president.

This doesn’t mean that high-speed rail has no place in the United States, although California’s extraordinary delays and cost overruns should act as a warning. Initially projected to cost $25 billion in 1999 — that would be about $37 billion in today’s dollars — it is now expected to cost $100 billion. After 22 years of wrangling about routes, land use, funding, and contracts, one 171-mile section between Merced and Bakersfield is under construction.

But when Biden talks about advances in plane and train technology, he speaks as if the main problems are that we’re not dreaming big enough and we’re not spending enough money. This is the rallying cry of a man who has never thought about the engineering challenges and who apparently never intends to think about them.