Submarines haunt the dreams of sailors around
the world. Secretive, stealthy, and able to strike from
out of nowhere, they remain the greatest threat to surface ships. Thankfully, submarines are limited in just
how fast they can move, typically with a top speed of 29 mph (46 kmh), which is well short
of a typical destroyer's top speed of 40 mph (64 kmh). Lagging behind their potential prey, submarines
must typically intercept their targets or lurk in sea lanes and wait for an enemy to
stumble into them. But what if subs could move much, much faster
than they currently do? Hello and welcome to another episode of The
Infographics Show- today we're taking a look at supersonic submarines- the US Navy's new
Superweapon. Moving underwater can be more difficult and
energy intensive than cruising along the surface, thanks to the huge amount of drag that water
exerts on a vessel and denser water a submarine encounters the deeper it dives. Thus while speedboats can zip along the surface
of the ocean at speeds of up to 90 mph (150 kmh), anything traveling beneath the waves
must exert exponentially larger amounts of energy to move as fast- something traditional
submarines are incapable of doing. Yet in June of this year it was revealed that
Chinese hackers had stolen sensitive data from a US contractor that had been working
on a top secret program to develop a supersonic missile to be launched from a submarine. While the data was only sensitive in nature
and not classified, it did hint at a major avenue of research the US was undertaking,
and hinted that the US Navy was not just interested in supersonic missiles, but supersonic submarines
as well. For US/China observers though, the revelation
was no surprise, as in 2014 China had made claims of huge technological breakthroughs
in developing their own supersonic submarines. But just how can you move a submarine through
the water at supersonic speeds without huge amounts of energy or absolutely destroying
the ship in the first place? Let's take a look at both the US and China's
approaches to the problem. The US proposal involves using something called
supercavitation- a technology that the Soviet Union developed in the 1960s for super-fast
torpedoes. The Soviet approach to moving a torpedo at
hundreds of kilometers an hour was to add a special segment to the nose cone of a torpedo
filled with pressurized gas, that gas in turn is ejected at extremely high pressures and
creates a bubble around the torpedo. A rocket motor, rather than a traditional
propeller, then pushes the torpedo along, and since it's avoiding drag from water the
torpedo could reach incredible speeds. The design was a success, but because of the
need to maintain a gas bubble, the range of the torpedo was only a few miles. By scaling the technique up dramatically,
the US hopes to be able to cocoon an entire submarine in a gas bubble, and then use powerful
rocket motors to blast across the ocean at speeds faster than sound. The physics involved show that the concept
could work, and already does at smaller, torpedo scales, yet so far the US has been unable
to overcome several obstacles. One of those being the difficulty in maintaining
the integrity of a large enough bubble around the submarine, and keeping it from 'pulsating'
dangerously. During current, smaller scale tests, the bubble
tended to expand and contract to such extremes that parts of the submarine model made frequent
contact with water. At extreme speeds that would be disastrous
and could rip a submarine apart, or at the very least create so much friction that the
submarine would go wildly off course. To overcome the problem scientists are experimenting
with moderating the rate of gas release at the tip of the submarine. China's approach to the problem uses traditional
supercavitation techniques with a new technique that involves spraying a special liquid membrane
onto the vessel's hull to reduce its friction with water. The vessel would gradually speed up with this
membrane being constantly sprayed on as it was worn away. Once hitting about 62 mph (100 kmh), an air
bubble could be formed and maintained. China's solution would entail the use of a
synthetic lubricant of sorts to help a vessel 'slip' through the water. It also provides a possible fix to one of
the biggest practical challenges facing supercavitating vessels: how do you steer it? Moving at such incredible speeds, if you were
to extend a fin or control surface into the water it would be immediately snapped off,
and the force exerted might throw your submarine into a spin which would lead to disaster. Yet by moderating the flow of their liquid
membrane the Chinese could ensure that one side of the submarine's bubble experiences
slightly more drag than the other, which would allow a sub to turn, dive, or rise as it sped
along at the speed of sound. If it truly works, it would be an elegant
solution to one of the biggest practical hurdles facing this entire concept. Yet a supersonic submarine would not make
for a very good offensive weapon, as submarines are in fact extremely vulnerable assets who's
best defense is stealth. A submarine crossing the ocean at supersonic
speeds may be able to get from San Francisco to Shanghai in 100 minutes, but it will generate
so much noise that even a deaf sailor would hear it. That would make a supersonic sub extremely
easy prey for surface anti-submarine ships, or other hostile attack subs. That's why the technology will likely not
be used for offensive purposes, but rather for logistical ones. Supersonic subs that could cross the Pacific
in just over an hour would be idea for quickly moving personnel and resources to conflict
areas, and would be incredibly appealing for the US which faces the prospect of coming
to the aid of its NATO allies in Europe in case of war against Russia. For decades Russia has counted on the fact
that in the case of war, it might be able to force a cease fire favorable to its interests
by quickly overwhelming European defenders and then digging in before the bulk of US
forces could arrive weeks later from America. Faced with the prospect of a difficult war
against an entrenched enemy, and the massive civilian casualties it would cause, NATO might
be more inclined to simply acquiesce to part of Russia's demands rather than wage a very
costly war. Yet a supersonic underwater transport vehicle
could change all of that by giving the US the ability to move large amounts of personnel
and equipment across the Atlantic in a matter of hours. That would make a US buildup possible in days,
rather than the weeks it would currently take to ship American attack helicopters and armor
across the ocean. Such a fast transport system would also give
US leaders a capability they have dreamt of for decades- the ability to put boots on the
ground nearly anywhere in the world within hours. As one US military officer once noted, the
ability to place a company of US Infantry anywhere in the world within a few hours would
stop a lot of wars before they started. Supersonic submarines could be revolutionary
tools for any nation's navy, yet the technical challenges are formidable and its unlikely
that they will be overcome anytime soon. Some worry that the pilfering of US secrets
by China may erode the US's military edge over its potential adversary, but the continued
theft of low-level secrets by Chinese hackers merely points at a culture that is more adept
at trying to steal revolutionary new technologies than to invent its own- something which should
be of serious concern for Chinese military planners. Would you ever take a ride on a supersonic
sub? What other military uses might a supersonic
submarine have? Let us know in the comments! Also, be sure to check out our other video
How Deep Can Submarines Go? Thanks for watching, and as always, don’t
forget to like, share and subscribe. See you next time.
