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Five Incredible Theoretical Aircraft

Aviation is a young field of engineering, having only been established just over a century ago when the Wright Brothers flew the first successfully airborne plane barely a hundred feet. That was in 1903, and within forty years, planes had gone from not existing to experiments with jet power. Forty years after that, we had fighter jets that could go Mach 2, and now, almost forty years after that, we have planes like the F-22 Raptor and the F-35 Lightning which practically fly themselves with all the computerized components within them.

The point to be made here is that aviation is constantly making huge leaps in capability, more or less in the blink of an eye. In the next forty years, it is entirely possible that the industry will again leap forward with concepts that feel like pipe dreams today. Here, we have for you a list of some of the possibilities for those concepts. These are just five ideas for some incredible theoretical aircraft.

Drones/UAVs

To start off the list, let’s begin with what is perhaps the most obvious direction for aircraft to go, and that is planes without pilots. As a side note, these entries are going to be more general as opposed to specific designs; we will provide some, but the focus is going to be on the concepts. In addition, you might be thinking to yourself, “Simon, drones aren’t a theoretical aircraft, they actually exist, this is false advertising and I want my money back.” First of all – no refunds. Second of all, you’re right, drones aren’t a theoretical aircraft, strictly speaking. But all signs point to them being the next big thing in aviation, and we’d be remiss if we didn’t mention them.

Before we get into that, let’s start with a brief history. Unmanned Aerial Vehicles, or UAVs, have existed as a concept since the field of aviation was established. For a while, the technology was largely limited to so-called “Target Drones”, as in radio-controlled planes used to train fighter pilots. But the appeal of UAVs was, to many, worth the cost of pursuing them; the loss of experienced pilots was of a particular concern, because not anyone can just be a fighter pilot, unfortunately.

It was during the Vietnam War that America used unmanned drones in combat for the first time, including the Lockheed D-21 and the Ryan AQM-91 Firefly. These early drones were primarily used for reconnaissance, particularly into China. As a side note here, when the Chinese government shot down some American UAVs and showed pictures of them to the world, the official response from the United States was, “no comment”.

Israel was the next major country to push development into UAVs, and again, they were primarily used for recon as opposed to weapons. However, they did find another purpose for them – as decoys, to trick the enemy into wasting anti-aircraft missiles on them. But Israel saw some merit in developing the concept further, creating several models including the IAI Scout and the Tadiran Mastiff, once again for reconnaissance. It’s at this point that UAVs start to resemble their modern counterparts, complete with data-link systems that share information in real time, along with live-feed cameras and long flight periods.

The power of these UAVs was demonstrated in the 1982 Lebanon War, when Israel used intelligence gathered by UAVS to thoroughly dismantle Syrian air-defense networks in one of the largest air operations since the Korean War. They destroyed almost 30 SAM batteries without losing a single plane.

This turn of events kickstarted another era in UAV development, and it was over the next few decades that the technology took off. Get it? America in particular has led the way, in both technology and controversy, with models such as the MQ-1 Predator and MQ-9 Reaper, equipped with Hellfire missiles to take out terrorists, and the occasional wedding.

Tasteless jokes aside, we’ve regaled you with the history of UAVs, so now let’s talk about their possible future. Right now, as many as one in three aircraft operated by the US Air Force is a UAV, and their number is set to increase as time goes on and the technology behind them improves. Right now, the single biggest push into this field is pilotless fighter drones, a la Ace Combat 7, because we just can’t seem to stop referencing that game when we talk about planes.

Assuming they’re made by then, pilotless fighters are probably going to be the single biggest military advancement of the century, since they would remove the biggest obstacle facing jet aircraft development – the pilot. Flying at Mach 2 and making 9G turns, as it turns out, is very stressful to the human body, and though you can make a plane out of stronger materials, the human body is rather more limited in that sense. As such, if you take out the pilot, you can design a plane with quite literally inhuman maneuverability.

In addition to this, it also makes fighting wars easier. If a country can mass-produce expendable fighter drones, they can send them to overwhelm enemy air defenses and disregard their own losses. After all, they’re just robots, right?

But this creates a dilemma. Should wars beeasier to fight? And as for the drones themselves, how should they operate – autonomously, or with a human controller? Putting the responsibility of ending human life into the hands of an algorithm is potentially a Pandora’s box that can’t be closed again. On top of that, it’s easy to imagine the devastation that could be wrought by countries with large air fleets of fully expendable bombers, who might otherwise think twice if their planes had to be flown by actual people.

And this question is not limited to fighters or bombers – there are already reports that, in 2020, a small autonomous UAV equipped with an explosive device hunted down and attacked a human target without being told to. The future of killer robots isn’t coming – it’s here now, and we need to decide what to do with these machines. If we don’t, they may decide it for us, whether actively or just by their existence. To that end, let us ask ourselves: what would Arnold Schwarzenegger do?

Solar-Powered Aircraft

The next entry on this list is, thankfully, of a lighter subject than the imminent war of the machines, and that is the looming prospect of total environmental collapse. Right now, the vast majority of aircraft, and almost all of the major military and civilian aircraft, run on fossil-fuel powered engines. But with climate change becoming an ever-present issue in our lives, there’s been a push to decarbonize many dirty industries in an effort to turn back the tide.

One of those industries is aviation, which account for anywhere from 2 to 4 percent of all carbon emissions, depending on how it’s measured. While that isn’t the worst offender in terms of carbon emissions, it is still a big problem on a per capita basis. Private jets owned by the very rich are a particularly bad offender in this regard, since they carry small crews while burning the same amount of fuel; even The Economist, a centrist newspaper, took the jump in calling for their total ban.

But aside from policy proposals, there’s other work being done on the side to make aviation a greener industry. Back in the early days of aviation, there were limited experiments with human-powered aircraft that could run without needing fuel. Those didn’t pan out, but they were the first steps in creating planes that could run on something other than fossil fuels.

Today, those kinds of experiments are being run again, but with a different system in mind – electrical power. A plane that ran on, for example, solar power would be in a much better spot, environmentally speaking, than one that ran on fossil fuels. In addition, the sun costs significantly less than a barrel of jet fuel – infinitely less, in fact, because the sun is free, while jet fuel is not. Since airlines typically operate on incredibly thin margins and fuel is one of their biggest expenditures, there’s not only an environmental incentive for the industry to electrify, but an economic one, as well.

The only problem is the tech. It takes an absurd amount of energy, relatively speaking, to get a plane off the ground, and much like buying an airline ticket in North America, you’re rarely getting a good deal for what you spend. Solar power, despite being cheap and renewable, just isn’t potent enough at the moment to power large passenger aircraft, and it isn’t clear if it ever will be. That hasn’t stopped people from trying, most notably with the Swiss company Solar Impulse, which developed a prototype solar plane capable of taking off under its own power, and which actually completed a circumnavigation of the globe in 2016. However, it took sixteen months for it to do so, demonstrating that, while making significant advances, solar aircraft are still in the development stage at this point.

There are other options. A plane could, in theory, store electricity on board before takeoff and use it while in flight, with solar panels to supplement the power usage. But batteries are another technology that are still maddeningly limited. Kerosene, the fuel that planes run on, has an energy density of just over 40 megajoules per kilogram; by comparison, the best battery has only one. Running planes on batteries presents another problem: the more batteries you put on a plane, the more power it needs to take off, which means you need more batteries… you see where this is going.

So, aircraft running on renewable energy still has some ways to go. But for electrical aircraft, there are other potential pathways, such as…

Hydrogen-Powered Aircraft

Hydrogen, the first element on the periodic table, and the lightest element in our universe. It’s a building block for stars, a component for many other elements, and it can also be used for gasoline. Or “gasoline”, as we’ll explain.

The concept of hydrogen as a fuel source has been around since the Industrial Revolution. In 1806, the Swiss inventor Francois Isaac de Rivaz designed the first internal combustion engine, which ran on a mixture of oxygen and hydrogen. Since then, the technology has been largely passed over in favor of other, easier to work with technologies, but it may have reached a tipping point in the last ten years, particularly with regard to cars. Right now, as of 2021, there are actually two commercially available hydrogen-powered cars, the Toyota Mirai and the Hyundai Nexo. That’s right, you can buy a hydrogen car, right now, for the low, low price of only about $60,000.

Erstflug HY4 am Flughafen Stuttgart. Am 29. September 2016 flog das Wasserstoff-Brennstoffzellen-Flugzeug HY4 über dem Flughafen Stuttgart.
Maiden flight HY4 at Stuttgart Airport. On September 29, 2016, the hydrogen fuel cell aircraft HY4 flew over Stuttgart Airport. By AZAD
Systems Co-production branch, is licensed under CC-BY

Still, that’s as good a proof of concept as any, and the obvious next question is: if we can power cars with hydrogen, why not airplanes? That’s, of course, slightly more difficult, and by slightly, we mean extremely. Theoretically, though, it is doable; small planes running on hydrogen fuel cells have been tested by companies like Boeing, so the concept is real, and the question is whether it can be scaled up to things like passenger jets. Several small companies are working on the idea, and Airbus, Europe’s largest airplane manufacturer, is dumping money into researching the concept, tentatively estimating a hydrogen powered passenger plane in 2035.

What’s the big deal, though? Why is hydrogen fuel so sought after? Well, hydrogen as a fuel source has some clear advantages. To start with, hydrogen is incredibly dense in terms of energy, relative to its weight. If you had a kilogram of hydrogen, you’d have 120 megajoules of energy. Remember from earlier that a kilogram of kerosene only has about 40, meaning that hydrogen fuel is three times more powerful than fossil fuels. In addition, hydrogen, being a basic element, is bloody everywhere, so supply shouldn’t be a problem. Lastly, hydrogen is a zero-carbon fuel – burn it for energy, and you’re left with water vapor.

One of the most powerful fuels in the world, and it’s all over the place, and it’s emissionless? Forget planes – why doesn’t everything run on this, right now? Well, that’s because hydrogen power, like fusion power, is amazing in concept, but fiendishly difficult to actually make work.

Here are the main challenges. Hydrogen, despite having high energy by mass, has low energy by volume. Picture a balloon: it doesn’t weigh a lot, but it’s rather big. For that reason, collecting enough hydrogen to use as fuel involves compressing it or liquefying it, which can be an energy-intensive process, not necessarily environmentally friendly. This compression also complicates the storage picture, because it needs to be kept at a very low temperature afterwards.

Also, given that it’s the lightest element possible under our current theory of physics, hydrogen is lighter than air, meaning that despite its abundance, it’s difficult to find in its pure form. Unfortunately, that pure form is the kind we need for fuel. Most of the world’s accessible hydrogen is currently locked up in compounds like water, which you’ll remember from high school science is made up of two hydrogen and one oxygen. Purifying the hydrogen from these compounds takes energy, which again, may or may not be green.

Hydrogen, it should also be pointed out, is flammable, a fact most famously demonstrated in 1937, when the passenger airship Hindenburg, running on hydrogen,burst into flames and killed 36 people. This isn’t a particularly salient problem – gasoline is also flammable. But still, hydrogen powered aviation has to overcome that, and hydrogen does have a tendency to leak from fuel tanks.

All of these are problems that can, in theory, be overcome with investments in research. But investment in this field is more cautious than others because of the uncertainty surrounding the tech, and also because of a high-profile scandal in 2020 with the hydrogen-vehicle company Nikola. Basically, the founder of the company lied about the whole business, it got into the news, and quite a few people, including the writer for this script, lost a lot of money on stocks. He’s not bitter, he assures me, he’s just disappointed.

Whatever the case, we can most likely expect to see more big things coming from this corner of the industry for the foreseeable future. Whether the power comes from the sun or from the building blocks of the universe, the trend for aviation is currently electric. Get it? Currently? Oh, whatever.

Quiet Supersonic Aircraft

Let’s take you back in time for a moment. Do you remember the Concorde? It was a British-French passenger jet that could travel at a speed of Mach 2, twice the speed of sound. It was also a huge financial black hole which never would have gotten off the ground if it weren’t for the support of the British and French governments.

Concorde is rather beloved by aviation aficionados, so to be clear, we’re not dragging on Concorde’s wings. Rather, the project was an illustration of the challenges facing supersonic flight for the commercial aviation industry. In no particular order, those were cost (Concordes were far more expensive than “normal” planes), ticket price (only the very wealthy could afford the average $8,000 tickets), fuel costs (it’s estimated that supersonic planes are anywhere from two to seven times less fuel efficient than other planes), and sonic booms.

The last one requires a bit more explanation. When a plane flies through the air, it creates pressure waves. Think of boats, creating waves in water as they go; it’s the same concept, but in the air. As the plane gets faster, those waves are compressed together, because they can’t get out of the way of each other. Those waves travel at the speed of sound, so when the plane itself reaches the speed of sound, all of those waves merge into a single, massive wave, creating a sonic boom. It’s fascinating, really.

It’s also a big problem for the Concordes of the world. The main issue is that sonic booms are bloody loud; loud enough to shatter windows. This was demonstrated in 1964 when the US Federal Aviation Authority and US Air Force intentionally caused over a thousand sonic booms in the skies above Oklahoma City just to see what would happen. (What happened was that they pissed off a bunch of Oklahomans, and the tests ended early.)

In any event, the US banned supersonic travel over land because of the issues of sonic booms, and as such the Concorde was limited to flights over the Atlantic Ocean. But that begs the question – if sonic booms could somehow be contained, could supersonic transport be viable?

That question is currently being explored by both private companies, small and large, and organizations like NASA. Experiments have been carried out that have shown it is, in fact, possible to reduce the shock of the sonic boom to more manageable levels. Right now, the most promising way to do this involves altering the shape of the plane to change how the shockwaves interact with each other, reducing the impact of the boom. Basically, make it look goofier, and it somehow works. It’s not clear how effective this will be on its own, but if other alterations to the design can make sonic booms quiet enough for overland travel, supersonic flight will almost certainly make a comeback.

Beyond supersonic flight is hypersonic flight, or flight at more than five times the speed of sound. That’s probably never happening, unless you’re talking about spaceplanes. Actually…

Spaceplanes

The last entry on our list has us going to the one place not yet corrupted by capitalism – space. Won’t be too much longer, though.

Now, there’s a few things we should get out of the way first. “Spaceplanes” technically do exist already, in a very limited form, since the actual definition of a spaceplane is a vehicle that can both fly through Earth’s atmosphere like, well, a plane, and also maneuver like a spacecraft in outer space. By that definition, the Space Shuttle was a spaceplane, though it required rockets to reach orbit.

But when we think of spaceplanes, we want to imagine science fiction spaceships that can take off and leave the earth’s atmosphere in one piece, without leaving anything behind. There’s actually a technical term for these kinds of craft – single stage to orbit vehicles, or SSTO. To date, no craft has ever reached orbit in a single stage, meaning that SSTO vehicles literally do not exist yet, in any form.

As explained previously, achieving liftoff with a plane takes a lot of energy, and leaving Earth’s atmosphere is the ultimate liftoff, the final boss of lifting off. So it’s difficult, probably the most difficult thing on this list to do. An SSTO vehicle needs to not only reach the loosely defined point above the Earth that counts as “space”, but it also needs to be going 17,000 miles per hour to achieve orbit. If it’s not going fast enough, it’s just going to fall back to Earth and die.

Planes, obviously, would struggle to reach that kind of speed. The fastest aircraft speed currently recorded is the X-15, an experimental rocket plane which reached a speed of 4,520 miles per hour. That was in 1967, and that record remains unbroken to this day; despite that, it’s still less than a third of the necessary speed. And you have to consider that the X-15 was deployed from another plane, and did not reach that speed from the ground.

This begs the question: is it possible for a plane to reach space? With a jet engine, probably not, since jet engines require air to function and the atmosphere acts as a speed brake due to air drag. But with rockets or some other kind of engine, maybe. This is all entirely in the concept stage at this point, so there are no models to go off of, but that also means your imagination can run wild with the possibilities.

Right now, all we can say about SSTO spaceplanes is that they are possible, barely, with the current technology that we have. But perhaps with advances in other technologies, perhaps if hydrogen fuel comes up roses or a miniaturized fusion reactor is created, then an electric engine can propel a plane into space all the way from the ground. But for now, on this front, the only thing in the clouds is our heads.

Skies Unknown

This was a dense video in terms of subject material, and we only covered a few examples of where aviation might go in the future; it’s possible another idea entirely takes over as the best option, or that literally none of this comes to pass. Whatever the case, we hope you enjoyed this list or at least learned something, whether that was about hydrogen, sonic booms, or what to do if you’re being hunted by a rogue robot. The answer, by the way, is to get down.

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