In the same spirit as my previous essays “What would a robot aircraft carrier look like?” and “What would a robot tank look like?” I’d like to examine what a robot submarine would look like. Specifically, an attack submarine, which is a sub designed to destroy surface ships and other subs (though sub-on-sub combat is INCREDIBLY rare). And by “robot sub,” I mean it is fully autonomous, with only robots and machines aboard and no humans.
And since there are many different kinds of attack subs in service across the world, I’ll focus on just one: the Virginia-class. This is the backbone of the American submarine fleet, and they’re among the most versatile and advanced in the world.
Regardless of country of origin, modern attack subs like the Virginias all share some basic design features: The vessels all have a cigar-shaped hull and a stubby wing-shape called the “sail” sticking up vertically. The rearmost 30 – 40% of the hull is dedicated to propulsion and fuel. The frontmost 10 – 20% of the hull is dedicated to the sonar and torpedoes. The remaining middle part of the ship is for the human crew and their needs, and consists of spaces like the control room, galley, kitchen, bunk rooms, bathrooms, and laundry room.
All of those rooms for humans could be deleted, allowing the sub’s overall length to be shortened by at least 20%. A shortened Virginia would be faster, nimbler and longer-ranged as a result thanks to reduced weight and drag: fluid dynamics shows that subs have the least drag when their breadth-to-length ratios are between 1:6 and 1:8. The latest Virginia-class subs are 34 ft wide and 377 ft long, a ratio of 1:11. Deleting the middle 25% of a Virginia would make its ratio 1:8.3, which is close to ideal.
An automated attack sub would still need robot “crewmen” to do maintenance and repairs, and as such would still need open spaces around important ship components like the engine and torpedo launchers that were spacious enough for the robots to move around them and access them. Additionally, the rooms would need to be connected to each other so robots could move around to meet the needs of the moment. As a result, the basic internal layout of a robot sub would be recognizable to a human submariner.
However, since robots could be created in any shape or size and could be programmed for any environment, many aspects of the sub interior would be very different. Because it is built around human ergonomics, manned Virginia-class subs have three decks (plus a curved storage space under the lowest deck), and on all parts of the ship the ceilings are high enough even for tall people. Without humans, things could be very different. The decks could vary in number and height from one compartment of the vessel to the next. Some might be too low for an adult human to walk through them.
This wouldn’t be a problem since robots of different shapes and sizes could be made for different parts of the sub: Robots the sizes of humans and cats could work alongside each other, and even tight, irregularly-sized areas would be accessible to them. Machinery, tools, cargo, and pipes would be arranged more space-efficiently than it is in human-crewed subs, and I imagine the interior being a bit like an ant colony.
Weird deck layouts could also be possible to maximize the use of space. Instead of three, perpendicular decks with the same ceiling-to-floor heights, imagine a much more complex arrangement where different parts of the ship have different numbers of decks. A human would struggle to keep track of this, but machines wouldn’t. Some of the decks might not even be flat.
The more efficient use of internal space could let us reduce sub’s volume without sacrificing anything. The shape of the hull could be transformed from the straight, cylindrical cigar-shape to a more streamlined shape that reduced drag. The rear half of the sub would taper down more sharply until it ended as a point where the propeller was. Internal volume would be lost in the rear, but the sub could still retain the same power and weapons.
An orangutan’s legs are almost the same as its arms.
As for the robots themselves, I can only be sure that their limbs will all be designed for grasping, like those of orangutans or spiders. In small, confined spaces, human legs are much less useful than a second pair of “bottom arms.” Filling the interior of the sub with metal gratings, handholds and ladders will make this body form even more useful. They could climb the walls and even ceilings to access everything, allowing better use to be made of the sub’s interior space.
For obvious reasons, they would also be waterproof to great depths. A crew of them could continue working even if their sub sank, and they might be able to fix and refloat it.
A Virginia-class sub on the surface.
The sail (often incorrectly referred to as the “conning tower”) could probably be made shorter, or even totally deleted, in an automated sub. The structure primarily serves as a lookout post and a place for submariners to shelter from the elements when their sub is on the surface. If automated, the sub could watch its surroundings on the surface by extending its periscope, and if its robot crewmen had to do something outside, they would be much less affected by rain, waves, and temperature extremes than humans. Attaching themselves to steel cables while working outside would probably be all that was needed to ensure their safety.
A sail greatly increases a sub’s drag and creates a “wake” behind it that interferes with the propeller’s rotation. Therefore, deleting or at least shrinking the sails should boost the sub’s top speed and fuel efficiency.
The lack of a sail would also make it easier for an attack sub to roll over like a log or like a football spinning through the air. This would let it make tighter turns, which would be useful in combat or when evading enemy attacks. Anyone who has turned around a curve too quickly in a car and felt it dangerously tilt is familiar with the effect of inertia in this context.
A boat tilting as it makes a sharp turn
While a rollover is disastrous on land, it wouldn’t have to be underwater if the vehicle didn’t make contact with any objects while spinning. Of course, even if a manned sub were technically capable of such a maneuver, it would wreak havoc since crewmen would be thrown around inside. Conversely, on an autonomous sub, the central computer could wirelessly alert all of the robots to upcoming rollovers, giving them time to brace themselves against surfaces and to grab handholds.
Measures would also need to be taken to ensure all the machinery and cargo was properly secured so it wouldn’t be thrown around inside the sub during rolls, but this is easy to do. A bigger problem would be dealing with the service interruptions in pieces of machinery not designed to operate inverted or on their sides, like the nuclear reactor and backup diesel generator. However, given the rarity of rolls (a sub would only need to turn very sharply in emergencies) and their short durations (a handful of minutes per sharp turn), it might not be an issue. Adding a backup electric motor and batteries that would kick in during rolls might be all that is necessary. (To be clear, an autonomous sub would still have a preferred “right side up” that it would be designed around, and under normal conditions it would be oriented in that way.)
Not having humans aboard also removes the need to keep the submarine interior full of oxygen. This is important since oxygen is corrosive and flammable. A robot sub would probably be filled with pure nitrogen gas instead because it lacks those qualities. As an inert gas, nitrogen protects computer chips, which would have obvious benefits for the robots and other machinery.
If, by the future date when autonomous attack subs are being built, backup diesel generators are still being used, then they will need oxygen. The generator room might therefore be the only place in the sub with an oxygen atmosphere.
Putting this all together, what does our robot attack sub look like? It would be a Virginia-class sub, but shorter, sailless, and with a visible taper from the middle of the ship to the propeller. The two horizontal steering fins on either side of the sail would be relocated to the sides of the hull. The robot sub would look like a hybrid of the unbuilt Soviet “Project 673” and American Conform-class attack subs, shown below.
The autonomous Virginia would have the same firepower, power plant, sensors, and stealth features as its manned variant, but it would be faster and more maneuverable, giving it an edge in combat and allowing it to attack targets across a larger geographic area. The deletion of the human crew would also greatly increase the ship’s mission endurance beyond the current 90 – 120 days, which is how long it takes for the food to run out. Thanks to the practically unlimited amount of energy provided by the nuclear reactor, an autonomous Virginia-class sub would only have to return to port if it expended all its weapons or had a serious mechanical problem.
The unmanned subs wouldn’t need to devote time to training missions since their central computers and robot crews could be reprogrammed in minutes as needed. The result of all of this would be a sharp improvement in submarine readiness rates and efficiency. Unmanned subs could patrol the same geographic area and do the same number of missions as a larger fleet of manned subs of the same type.
When I was in college, my mother bought me a new, cheap car for my 21st birthday. It lasted me for 19 years and 209,000 miles–my companion through two or three chapters of my life–before finally dying of a seized engine last month. Finding a replacement in a hurry plunged me headlong into the world of cars, and a side effect of all the research and car inspections I did before buying a new one was an understanding of how future technology will revolutionize cars and the industries related to them.
Better designs
My old car was a Chevrolet Cobalt. Over the years, I’d learned a lot about it from working on it in my driveway, so it was sensible for me to consider buying a new one, but the model was discontinued in 2010. That led me to consider its successor, the Cruze, which I assumed would share many design elements with the Cobalt.
The engine bay of a Chevrolet Cruze
Unfortunately, I discovered the Cruze has an average-at-best reputation among compact cars thanks to problems with its engine and some of the components directly attached to it. The use of lower-quality components was the main culprit, and there was also a case to be made that some aspects of the engine design itself were not as well thought-out as they should have been.
I bet GM’s engineers didn’t know about these problems, or at least didn’t know they would turn out to be so pronounced, until after a million Cruzes had been sold and at least two years had passed so the problems could be exposed through real-world driving conditions. I also doubt the problems would have arisen at all had those engineers had access to the kinds of advanced computer simulations we’ll have in the future.
Using hyper accurate, 1:1 simulations of materials and physical laws, car designers could test out unfathomably large numbers of potential car designs and experiment with different components and combinations of components until optima were found given parameters like maximum cost and minimum performance. Each simulated car could be “driven” for a million miles under conditions identical to those in the real world, thus revealing any design or material deficiencies before any vehicle was actually built. (These kinds of simulations already exist, but are so expensive to create that they’re only used to model things like nuclear weapons and stealth bombers.)
Thanks to this, cars in the future will be better and more reliable than they are today, and there won’t be such things as specific car models like the Cruze that have bad reputations for unforeseen problems. All vehicles will be optimized and all car companies will use the same tools for designing their products (which I also imagine would lead to many convergences).
More diligent maintenance
With the Chevy Cruze out of the equation, I considered another compact car, the Nissan Versa. My research quickly led me to discover that Nissan cars have become infamous among owners and mechanics for transmission failures. This is because most Nissans have “continuously variable transmissions” (CVTs) instead of traditional 6-speed automatic transmissions or 5-speed manual transmissions.
CVTs are cheaper to manufacture than the traditional transmissions and improve the fuel efficiency of the cars they are integrated into. However, CVTs require more maintenance because they get hotter during operation and produce more metal particle debris due to more metal-on-metal contact between moving parts. Replacing the transmission fluid and filter largely solves the problem and should be done every 30,000 miles in a Nissan car with a CVT.
Old transmission fluid draining out of a car
To put this into perspective, a 2013 Toyota Corolla with a 5-speed automatic transmission only needs the same transmission service every 100,000 miles. Most car owners still expect that kind of maintenance interval in all new vehicles, and this mismatch between expectation and reality explains most of the Nissan Versa’s bad reputation. It doesn’t help that Nissan itself has downplayed the higher maintenance requirements of its CVT vehicles, or that the kinds of cash-strapped people who buy Versas tend to know little about cars or how to take care of them.
More broadly speaking, improper maintenance is something that car mechanics constantly complain about (even if it generates a huge amount of business for them). Most cars die prematurely due to owners ignoring obvious problems and not properly maintaining them. Some “bad” cars like the Versa aren’t actually bad, they just need more maintenance than others to stay functional. However, learning about this through research and then staying mindful of your particular vehicle’s maintenance requirements is too much for most human car owners thanks to a lack of time, energy, and sometimes intelligence.
Intelligent machines won’t have those same limitations. Future cars will have better self-diagnostic capabilities, and will be maintained by robots that will never skip preventative care. And since machines will work for free unlike today’s human mechanics, the costs of this will be much lower. Even poor people will have enough money to change the transmission fluid in their Nissan Versas.
Gentler driving
Facebook Marketplace was my primary source for my used car search. In a huge fraction of the ads, the owners wrote their cars had “Salvaged titles” or “Rebuilt titles.” That means the car sustained so much damage that its insurer declared it “totaled,” meaning the cost of fixing it exceeded the resale value of the car in its state. Instead of being scrapped, many cars like this are bought at very low prices by mechanics who fix them themselves and resell them for a profit. Those profits tend to be small because having a Salvaged or Rebuilt title is a scarlet letter in the open market because buyers know such a vehicle was badly damaged at some point, and can’t be sure of the full extent of the problem or of how fully it was remedied. I ignored all the cars without clean titles.
Why do cars end up with Salvaged or Rebuilt titles? Mostly because they were in serious accidents, floods, or caught on fire. Autonomous vehicles will, once fully developed, drive much more safely than humans and get into far fewer accidents. Eventually, they probably won’t even have steering wheels or pedals, making car thefts and ruinous joyrides impossible.
As I discussed in my blog Hurricane Harvey and Asimov’s Laws of Robotics, autonomous cars could also avoid floods by keeping watch of their surroundings and driving to higher ground if they were at risk of being submerged. Better monitoring systems would also reduce instances of car fires since the cars would be able to shut down their systems if they sensed they were overheating, or to immediately call the local fire department if they caught on fire.
More careful driving and avoidance of other hazards will sharply lower the odds of a car having to worry about getting a Salvaged or Rebuilt title. Gentler driving that stayed mindful of the car’s engineering limits and avoided exceeding them would also lengthen vehicle lifespans since components would take longer to wear out.
Conclusion
In the future, vehicles will drive safer and will last much longer than they do today. They will be designed better and will incorporate more advanced materials like future alloys. Moreover, once battery technology reaches a certain threshold, the vehicle fleet will transform to almost 100% electric in a few decades, and electric vehicles are inherently more robust than gas and diesel vehicles we’re used to because they have fewer parts and systems.
On a longer timeframe, autonomous driving technology will achieve the same performance as good human drivers, and the average vehicle will become self-driving. Machines will drive much more safely and gently than humans, making it much rarer for cars to be damaged in accidents or by driving behavior that overstresses their components.
Future technology will also benefit car maintenance. The vehicles themselves will have better inbuilt self-diagnostic capabilities, so they’ll be able to recognize when something is wrong with them and to alert their owners. The proliferation of robot workers of all kinds will also lower the costs of maintaining cars, meaning it will not be so common for owners to skip maintenance due to lack of money. The robot butler who hangs around at your house could work on your car in your driveway for free, or your car could drive itself to a repair shop where machines would service it for low cost.
Under all these conditions, the average car’s lifespan will be over 500,000 miles in the future (today, it’s about 200,000 miles), being stranded because your car broke down will be much rarer, and personal vehicle transportation will be within the means of poorer people than today. Ultimately, cars might only get totaled due to unavoidable freak accidents, like trees suddenly snapping in the wind and smashing down on one of them, or to deliberate vandalism by humans. Likewise, after humans discover the technologies for medical immortality, we’ll only die from accidents, murder and suicide.
These technology trends will also upend the used car industry. With machines carefully doing and logging all the daily driving and maintenance, secondhand buyers won’t have to worry that the vehicles they’re looking at have secret problems. With highly accurate data on each car’s condition, haggling would disappear and pricing would reflect the honest value of a used vehicle.
People in the used car industry who make a living off of information asymmetries (the worst example is a car auctioneer who only lets potential buyers examine a car for a few minutes before deciding whether to buy it) would lose their jobs. In fact, AI and autonomous vehicles would let car manufacturers, fleet owners like rental car companies, and private owners sell their vehicles directly to end users without having to go through any middlemen at all. AIs that work for free would replace human dealers and would talk directly with customers who wanted to buy cars. A personal inspection and test drive could be easily arranged by sending the autonomous car they were interested in to the buyer’s home, no visit to the car lot needed.
A few years ago, I did a thought exercise where I deduced what a robot tank would be like. I concluded that the lack of human crewmen would allow such a tank to be shorter, lighter, and less voluminous than manned tanks, but that it would still look unmistakably “tank-like” and would be in the size range of current tanks. Thus, the future of armored warfare will look much the same as its present, even if a lot of new technology will be hidden under the hood.
Now I wonder if this would be the case for warships. Given their great variety, I have to restrict my analysis to just one type, the aircraft carrier, but my key conclusions can probably apply to the rest. And since there are many types of aircraft carriers, I’m focusing this analysis on supercarriers in particular, which only the U.S. Navy has at present. The newest American supercarrier that is also fully mission-capable is the U.S.S. George H.W. Bush, and as such, it’s fair to call it America’s “best” aircraft carrier. So what would a robot George Bush look like?
The USS George H.W. Bush
First, the ship’s gross architecture would stay the same. It would need an oblong hull with a pointed front to minimize hydrodynamic drag. The top would need to be flat and uncluttered so planes could land on and take off from it. Even in the far future, most planes will still take off and land the traditional way on runways. Even with more advanced aircraft technology, fighter planes won’t hover straight up into the air to take off. Vertical takeoff and landing (VTOL) will, thanks to physics and the usefulness of “lift,” always be a MUCH less fuel-efficient way to get airborne and then return to the ground than speeding down a runway. Every extra pound that a VTOL plane needs to land and take off is one pound it doesn’t have for weapons.
The George H.W. Bush’s island structure.
In fact, the only external difference between the U.S.S. George H.W. Bush and its robot equivalent would be the ships’ islands. On an aircraft carrier, the “island” is a vertical protrusion on the otherwise-flat flight deck, and it somewhat resembles a small office building. It provides mounting points for radars, radios, and other sensors, and also contains the bridge, flight control room, and smaller rooms for specialized tasks.
These photos show the bridge of one of the Bush’s sister ships.
The captain and his command crew are in the bridge, where they monitor and control overall ship operations. The flight control room is one level above that, and is where other officers coordinate aircraft movements on and off the carrier. It’s obvious why these crewmen need to be situated in a high place where they have good views of the ship’s flight deck and the surrounding waters. In turn, the physical sizes of human bodies and our need for clearance space to walk around each other dictate the dimensions of those rooms, and ultimately, the shape and size of the island. Thus, this part of an aircraft carrier is designed around the human form.
On an automated aircraft carrier, such considerations could be dispensed with since humans wouldn’t be aboard. Visual monitoring of the flight deck and seas could be done with cameras, allowing the bridge, flight control room, and other small rooms in the island that support their functions to be deleted (computers located deep inside the ship’s hull would watch the video feeds). As a result, the office-building-like island would be thinned down to a mast. It might be of a metal lattice design, or could be solid with a geometrically faceted exterior to reduce the ship’s radar signature.
A British frigate with three masts of two different designs. The one at left is geometric, while the two at right are simple metal lattice towers. A robot aircraft carrier’s island would look like one of these.
A thinner island would help a robot aircraft carrier by increasing its flight deck area and reducing the air turbulence over it. The ship’s survivability would also be improved since its command staff wouldn’t be kept in an exposed, vulnerable location. Instead, it’s command functions would be done by a central computer located in an armored room below decks.
A Nimitz-class carrier like the George H.W. Bush typically contains 56 planes (mostly fighters like the F/A-18) and 15 helicopters. Our robot version of the carrier would have autonomous versions of those aircraft. Since the planes lack human pilots and crewmen, things like ejection seats, steering controls, bubble canopies, computer screens, and oxygen pumps could be deleted, reducing gross weight. That weight savings would let the aircraft take off and land a little more easily, possibly reducing the lengths of runway they needed, and hence reducing the overall length of the ship.
However, any such benefit would be tiny since the weight of the pilot and his supporting equipment is relatively minuscule. For example, an F/A-18 Super Hornet that is fully fueled and armed for a combat mission could weigh over 50,000 lbs, less than 1,000 lbs of which is represented by the pilot and his aforementioned support gear. An unmanned F/A-18 might be able to take off and land on a runway a few feet shorter than the manned version, but that’s it. Therefore, the lengths of the runways used for takeoffs and landings on the robot carrier would either be the same as those on the human-crewed counterpart, or imperceptibly shorter.
The reduction of the island’s mass might result in the flight deck being slightly narrower since the port side of the deck wouldn’t need to flare out as much to counterbalance the weight of the starboard side.
A careful look at this head-on view of the George H.W. Bush reveals that the port side of the ship (right side in this photo) juts out farther from the ship’s centerline than the starboard side (left side in the photo). This asymmetry exists to balance out the island’s weight.
The robot ship’s “freeboard,” which refers to the vertical distance between the surface of the water and the top of its flight deck, would be the same or very close to the manned version’s, which is 57 feet. In general, as ships get longer and heaver, they need higher freeboards to keep stable. A high freeboard is also very important for ships meant to sail through rough seas, which an aircraft carrier would need to do since wars don’t pause for bad weather anymore. There’s no reason to think the manned USS George H.W. Bush’s freeboard is not optimal given the ship’s size and function, nor is there evidence that the crew’s uniquely human needs affected the freeboard.
The USS Midway appears to sit lower in the water than the USS George H.W. Bush
The argument for this optimality is strengthened by the example of the USS Midway, another aircraft carrier that served the U.S. Navy from 1945 to 1992. In the 1960s, it went through a major renovation in which the flight deck was widened to accommodate the bigger planes that were entering service, which added substantial weight to the ship and made it sit lower in the water. The reduced freeboard hurt the Midway‘s performance in rough seas, and the ship also had more problems with waves splashing into the ship’s open side elevators, and even splashing over the bow to soak the flight deck. The problems kept it from conducting flights in sea conditions that the George H.W. Bush could still operate in. The contrast between the ships further supports the conclusion that the Bush’s freeboard is already optimized, and wouldn’t be different or would only be a tiny amount different in an autonomous version of the ship.
To summarize this analysis of the robot carrier’s exterior, it might have have a slightly different profile and slightly different dimensions to its flight deck compared to the manned version. However, this would be very hard to see, and by far, the most visible difference would be to the island.
The ship’s interior layout is the most subject to human needs since it is where almost 6,000 people work and live, 24 hours a day, for months on end. Before moving on to that half of this analysis, it’s important to point out that an autonomous aircraft carrier would still need crewmen, though they’d be robotic. They would need to be able to move around the ship for inspections, maintenance, repairs, emergency response, and to transport things. Therefore, the inside of the robotic George H.W. Bush would still be comprised of rooms, doors, stairways, and passageways to enable the crew to access every part of the ship.
To understand how the ship’s interior layout would change if human-centric design concerns were abandoned, first study these cutaway illustrations of the George H.W. Bush’s class of ships:
A simplified cross-section of the USS George H.W. Bush.
The USS Nimitz is one of the USS George H.W. Bush’s sister ships.
A side view of the USS Ronald Reagan’s interior, another of the Bush’s sister ships. A larger version that you can zoom in on is at the image creator’s website: http://patrickturner.com/carrier.html
A cutaway showing the size and location of the USS Ronald Reagan’s hangar deck.
Let’s start by distinguishing the features and sections of the ship that exist because of the presence of humans, or are larger than they need to be because of human physiology, from the features and sections that do not. The hangar is massive and is necessary to house the carrier’s aircraft for maintenance, repairs and modifications. It’s size is dictated by the sizes of the planes and by the need to have enough space around each one to be able to move them around and provide crew with access to them. There’s no reason to assume the size or layout of the hangar deck would be different if the carrier were autonomous, so the largest single room in the ship would be the same.
This is also true for the series of large rooms at the ship’s lowest point, called “the fourth deck,” which contain its nuclear reactors, electrical generators and gearing that connects the engines to the propellers. Smaller rooms on the fourth deck that store jet fuel, munitions for the planes, and water for the steam catapults are also not designed around human needs. (They are stored at the lowest part of the ship to keep its center of gravity low, improving its stability.)
It’s impossible to generalize about all the other decks of the ship since rooms dedicated to purely mechanical functions (e.g. – jet engine repair shop, steam catapult piping spaces) are mixed in with those dedicated to human crew needs (e.g. – bunk rooms, hospital, cafeteria). All we can say is those of the former category would stay, while the latter would disappear, leaving a lot of empty space.
The robot crewmen wouldn’t need to eat, sleep, party, or satisfy hygienic needs, and would probably stay at their work stations almost all the time. The only room dedicated to their unique needs might be a specialized repair shop and spare parts room. Those rooms would take vastly less space than the bunk rooms, bathrooms, cafeterias, bakeries, laundromats, conference rooms, etc. that would need to be there to satisfy a human crew’s needs.
The ability to work constantly would also allow a robot crew to be smaller than a human one without reducing work output. Assuming an average sailor works a 12-hour day and works as efficiently as a robot when he’s on duty, 3,000 robots could to the work of 6,000 humans. The disparity might actually turn out to be more extreme.
Getting rid of the human crew wouldn’t just save internal space–it would save weight. The clothing, beddings, beds, furniture, cooking appliances, laundry machines, bathroom fixtures, lockers, food, and water (in excess of what is needed for the steam catapults), plus the plumbing and electrical/data cables needed to support some of those features add up, and if the humans disappeared, so would all of those things. Ironically, a robotic aircraft carrier would also have fewer computers and display monitors in it since the machines wouldn’t need them because they’d be able to directly interface their minds with the ship’s sensors and main computer. Lessening the number of devices would also save weight.
Moreover, the need to divide a ship’s internal space into rooms that only exist due to human needs, like walling off an area to create privacy for a bathroom, adds weight since the walls themselves are heavy. If the ship weren’t designed around human needs, more parts of the ship could be large, open areas, cutting overall weight.
With these considerations in mind, a low estimate for the amount of weight saved by eliminating the human crew is one ton (2,000 lbs) per person. The total weight savings is therefore 6,000 tons, which is a small but still helpful boost for a vessel displacing 114,000 tons.
Our robotic version of the George H.W. Bush could deal with its excess internal volume and weight savings in a three different ways. The simplest option would be to just accept having more empty space inside of itself, and to capitalize on the slight increase in sailing speed and ship energy efficiency that would owe to being lighter. The ship would have the same number of decks and the same internal volume and the manned version, but the rooms would be larger, there would be less of them, and they would be less full of stuff. This option would let the carrier be more mission flexible since it could double as a transport.
The Nimitz-class USS Theodore Roosevelt undergoing replenishment at sea. Note the temporary cables connecting the ships, which are used to move supplies.
The second option would be to fill the robot George H.W. Bush‘s newly empty spaces with 6,000 tons of other stuff to improve its performance in some way. Nimitz-class aircraft carriers are powered by nuclear reactors whose uranium lasts for 20 years, so it wouldn’t help to add spare uranium rods to the ship (refueling is done in port for the sake of safety, anyway). However, other types of essential supplies are depleted over the course of a multi-month cruise, forcing a carrier to halt operations so it can pull alongside a cargo ship for a tedious resupply process called “replenishment.”
The lack of human crewmen would mean the carrier would no longer need food replenishments, but it would still need replenishments of aviation fuel, munitions, and spare parts for its aircraft and itself. Given that a Nimitz-class ship’s 8,500 ton supply of aviation fuel , called “JP-5,” only last about seven days during routine operations, and even less during round-the-clock combat operations, the robot version of the ship would derive the most benefit from adding more fuel tanks.
If the capacity of the robot George H.W. Bush’s aviation fuel storage tanks increase from 8,500 to 14,500 tons, if JP-5 is 6.8 pounds per U.S. gallon, and if a gallon of liquid is 0.134 cubic feet, then we can calculate how much volume the added 6,000 tons of fuel will take up inside the ship.
Glimpsing at this cross-section of the George H.W. Bush again, we see that aviation fuel in stored in long tanks stretching along the port and starboard sides of the ship (item #8 in the image). At the waterline, the ship is 1,092 feet long, and the draught (the distance between the waterline and the bottom of the ship’s hull) is 37 feet. So if we add 236,470 cubic feet of fuel tanks to the existing tanks indicated in the illustration…
1,092 feet x 37 feet = 40,404 square feet on port side and starboard side (80,808 total) 236,470 cubic feet / 80,808 square feet = 2.9 feet
…then we could fit in the extra fuel by widening the existing storage areas by a mere 2.9 feet. As a result, in the above illustration, item #8 would be very slightly wider on both sides of the ship, and item #10 would be very slightly narrower by the same amount. Adding 6,000 tons of aviation fuel is very doable.
The result would be a ship that weighed and handled the same as its manned counterpart, but could launch airstrikes against enemies for longer periods of time before having to pause to get a gas refill from another ship. The robot carrier’s upper decks would have a lot more empty space than the manned version, but it wouldn’t be able to fill it up without slowing itself down.
The third option would be to get rid of the surplus human spaces by deleting some of the ship’s decks, in turn reducing the carrier’s total interior volume. The mission-essential rooms that remained, like the repair shops and spare parts storage rooms, would then be reconfigured so they filled up the ship’s interior efficiently, with no empty spaces or oversized rooms. If you could explore this robot George H.W. Bush version, it would seem as claustrophobic as its manned counterpart, though it would take less time to tour the latter since it would have one or two fewer decks.
This modification would cut even more weight from the vessel, allowing it to travel faster with the same nuclear reactors, or to travel at the same speed with smaller reactors. The reduced mass would also make it faster and cheaper to build.
“Freeboard” is the vertical distance between the water’s surface and the top of a ship’s hull, and “draught” is the vertical distance between the bottom of a ship’s hull and the water’s surface.
But this design change raises a potential problem: If we reduce the number of decks in the ship, then we reduce its overall height from the bottom to top. As discussed earlier in this analysis, we can’t reduce the freeboard because that’s already optimized. That means we have to reduce the “draught” (also called “draft”), which is the vertical distance from the bottom of the ship’s hull to the water’s surface. However, reducing the draught too much can make a ship unstable.
The George H.W. Bush‘s draught is 37 feet. If one deck were deleted, the draught would be 28.5 feet, and the ship’s weight would also decrease. Let’s say it drops from 114,000 tons to 100,000. Would the ship still be stable? Maybe. After all, there are several cruise ships whose dimensions with nearly identical dimensions, and they’re very seaworthy:
Ship name
Tonnage
Draught (ft)
Length (ft)
Width (ft)
USS George H.W. Bush (manned)
114,000
37
1,040
134
USS George H.W. Bush (robot) minus one deck
100,000
28.5
1,040
134
Carnival Sunshine
103,881
26.25
892
125
Costa Fortuna
102,587
27.23
892
125
MSC Orchestra
92,409
25.75
964
105
Norwegian Pearl
93,530
28.3
964
105
The cruise ships with draughts of 25.75 – 28.3 feet can handle rough seas, so the table suggests our robot aircraft carrier would presumably be able to do so just as well with a draught of 28.5 feet. However, it’s possible the demands placed on a ship designed for war are different from those of a ship designed for recreation, making a 28.5 foot draught insufficient for an aircraft carrier. A warship probably needs to be able to accelerate harder, make tighter turns, and endure worse weather conditions than a cruise liner. Unlike my research on the freeboard, I wasn’t able to find data on the optimal draught for a carrier, so I can’t answer the question, I can only conclude that a robotic aircraft carrier might have fewer decks and less internal volume than a manned counterpart.
In conclusion, while a robot version of the U.S.S George H.W. Bush wouldn’t look much different from a manned version on the outside, there would be substantial differences on the inside. All of the rooms and items that existed to service the needs of the human crew (bunk rooms, bathroom, cafeterias, offices, furniture, display monitors, etc.) would be missing. If the robot version retained the same amount of internal space as the manned version, then it would feel much emptier and more open inside. Its performance would also be superior to the manned version in one or more areas (e.g. – faster, more fuel for planes, better mission flexibility thanks to more storage space). If the robot version were designed to exclude excess volume, then it would feel about as constricted as the manned version, and it’s interior would be smaller, making it faster to do a full walking tour of the ship. A less capacious version of the USS George H.W. Bush may or may not have better performance in one or more areas than its manned counterpart, but for sure, it would be faster and cheaper to manufacture, allowing a country to make more ships for the same amount of money.
Finally, another observed difference would be lower levels of activity on an autonomous aircraft carrier since there would be far fewer crewmen. Moreover, since the crew would all be robots, they wouldn’t need to roam the ship to visit bathrooms, the cafeteria, buddies, or their bunks–they would stay put at their duty locations almost all the time. For example, a robot that fixed airplane engines would spend all its time in the engine repair shop. If it needed power, it would plug itself into a wall outlet in that room. It might only ever leave the room to visit the robot repair shop when it broke.
The robots would be of different sizes and designs to suit different roles on the ship. Obviously, they would need to be waterproof and capable of working normally underwater, to some reasonable depth and pressure level (100 – 200 meters). Unlike human crewmen, if the carrier were sinking, they would stay inside and focus on fixing the vessel, reducing the odds of it being lost. They could even keep working in parts of the ship that had filled with water.
Contrast that scenario with the premature abandonment of the U.S.S. Yorktown in WWII, which happened because the captain erroneously assumed the ship was doomed, and the human crewmen were afraid to risk their lives by remaining on it. The central computer of a robot George H.W. Bush would not make such a mistake, and its robot crew would unfailing execute its orders until the end, even in the worst of circumstances.
