Is stealth even possible?

Previously I solved the Mechs vs Tanks question. Now let's move on to the next one - is stealth even possible, specifically on military aircraft?

Aircraft is usually detected at long distances by radar. Stealth aircraft has been a thing since 1980s - it uses various tricks to make it harder to detect over long distance by typically used kinds of radar, and that's effective enough.

There's been many attempts to use different kinds of radar systems to detect stealth aircraft. They're probably at least somewhat effective, but this information is not really available to anyone. Not even in the sense of being some military secret - how well Chinese detection technology can deal with US aircraft is unknown to both China and US, and likely won't be until China invades Taiwan and needs to test in it practice.

Phone cameras

However, why limit ourselves to radar? Let's do some back of an envelope calculations.

Military aircraft is about 10-15m long and wide, and moves through open space at very high speed. That's not like any natural object. Let's approximate that to 10mx10m square.

Modern consumer phones have cameras of about 100MP, or 10000x10000. If we imagine that it covers 90 FOV, then if it points at a 10km by 10km area, 10km up, each pixel covers about 1m x 1m - so aircraft will cover about 100 pixels and will be trivially detectable by even dumbest Python image recognition script, at least in daytime.

Let's assume we want to defend a big country like Iran from people fed up with its terrorism. Iran has area of 1.65 million km². As our phones each look at area 100km², spreading them so every point in the sky is seen by 10 phones at the same time - for huge redundancy, it would take just 165k phones, or at $500 each just $82m, less than one jet.

If we require lower coverage multiples, phones get better or cheaper, or we can detect enemy aircraft from less than 100 pixels, that drastically reduces the cost.

One might think that horizon would be a problem, but phones in this example are looking up, and horizon is 5km away at 2m tall pole, and 10km away at 8m tall pole.

Various terrain features like mountains are a problem for radar system - as radars are big and expensive and therefore very few. But we can cheaply install so many damn phones this problem is absolutely trivial.

Image Processing

Someone not familiar with modern image processing might imagine that detecting aircraft from a picture would be hard. Nowadays this is honestly a ridiculous idea. You can create fake tanks to fool the AI, but there are zero big fast moving objects in the air other than aircraft, and once you know aircraft is there, it really doesn't take much to figure out if it's a friendly, neutral, or enemy kind.

I can also think of no reason why similar image processing algorithms could be used to integrate various radar signals, even if each of them separately couldn't really detect stealth aircraft.

Drones

There's no reason why the cameras can't be even better, with some optics added to get performance we need, and put on drones staying in air long time. Sure, drones could be shot down, but drones are extremely cheap and only getting cheaper.

The main problem with cheap consumer drones is that they typically have flight time of only about 20-30mins, so constantly recharging and relaunching them would use a lot of manpower.

So while phone cameras and image processing technology is ready for this today, it might take another decade or two before drone technology catches up.

Limitations

This approach works far better in daylight than during the night. Night isn't completely dark, so detection might be possible, but it would likely be far more expensive.

It only applies to stealth aircraft, as it flies through open and featureless skies, and it wouldn't work at all with stealth submarines, or even to ground based vehicles since ground is covered with interesting features which could obstruct view or make detection difficult.

Another obvious limitation is that this technology only covers your own country - at least with ground based phones. It won't help you at all if enemy plan is to just show up at your borders, fire some missiles, and head back home.

The whole idea is to have a lot of really cheap short range detectors to defeat stealth, but stealth can still deal with long range detection by radar.

This limitation can be somewhat overcome by deploying camera drones. Drone flying 1km up has horizon at 110km, so it could monitor aircraft approaching your airspace, but that's just a 3 minutes warning, so not exactly amazing.

Another use of this technology could be detecting enemy navy. You'd need to use long flight time drones for that due to distances required, but ships are really big and much slower than aircraft. Then again, surface stealth ships are an extremely marginal thing.

Obviously everything here is back of an envelope calculation. But people's widespread belief that stealth technology is some kind of magic really looks ridiculous to me.

US military has terrible track record of losing wars

By just about any metric US military is by far the most powerful on the planet. The most powerful this planet has ever seen.

Yet, if you look at how it's been doing since WW2, it looks real bad.

I'm only including meaningful wars here, not just throwing a few bombs here and there.

Scorecard

I'll rate them on scale of: total failure, narrow failure, clear draw, narrow victory, total victory

Korean War - clear draw. After a lot of fighting everyone was pretty much where they all started.

Vietnam War - total failure. It doesn't get any clearer, nothing was left of what US spent so much time defending.

First Iraq War - narrow victory. Saddam was on verge of losing power, but US indecision let him crush the rebels and remain in power, remaining a problem for long time afterwards.

Afghanistan War - total failure, Taliban still controls most of Afghanistan, and Afghan government is basically negotiating terms of surrender.

Second Iraq War - narrow failure, Saddam was overthrown, but US got forced out by insurgents, and Iraq was 1/3 controlled by Islamic State, the rest by pro-Iranian puppet regime. After ISIS got defeated, pro-Iranian puppet regime controls Iraq.

So of big 5 wars, there's 2 total failures, 1 narrow failure, 1 clear draw, 1 narrow victory, and 0 total victories.

Is that what the world's biggest budget can buy?

It's not difficult to see the pattern. US military is terrible at counter-insurgency, and extremely unwilling to tolerate even modest casualties.

Many US cities are more dangerous than warzones US has been fighting, but even those modest losses are just too much.

So what is it good at?

So the question is - for all that money - what is it actually good at?

It's not actually clear it would be good at WW3 - most likely result is that everybody living in every major city anywhere dies from nuclear missiles.

At purely conventional version of WW3, general consensus is that Soviets would have conquered big parts of Western Europe before Americans would even show up. Not like Soviets had any intention of not using nukes. Every countries which couldn't retaliate was the target, including neutral countries.

It's really unclear that US would be able to win any of the likely regional conflicts with near-peer enemy.

It's not clear if US has any meaningful way to stop China from taking over Taiwan. China has effective ways to prevent any US ships from coming close.

Likewise if Russia wanted to conquer Ukraine or the Baltics, US wouldn't be able to do anything to prevent that.

This is mostly because geography favors its opponents in such cases.

US can win conventional fight against Third World countries, like Iraq in 1991 (on paper Saddam had one of 10 strongest armies in the world), but without willingness to accept costs of occupying those countries and ability to wage effective counter-insurgency this is of limited effectiveness.

US can bomb any Third World country it wants, but effects of that have been rather limited so far.

And US has no ability to defend its own borders - from illegal crossings - but that's intentional political failure.

It's by no means terrible, but relative to how much money is spent on it, it looks quite disappointing.

Mechs vs Tanks

Sci-fi and anime loves mechs, but there's a widespread belief that mechs are just absolute trash idea, and tanks are superior in every way.

Here's example of such claims: part one, part two.

This is completely wrong.

Cube Square Law

Part of the problem is conflating the idea of a mech, with the idea of a giant mech. Mechs can come in all sizes.

And in fact military is already actively researching mechs! Just among many such projects - DARPA's TALOS project is an bulletproof, weaponized, AI-enhanced exoskeleton - basically a small mech.

It might take a few decades before such mechs become deployed by actual armed forced, but it's ridiculous to call something crazy when prototypes have been in development for years now.

Weapons vs Armor

History of warfare is an endless race between weapons and armor, with either being on top at different times.

During the Middle Ages, armor was king, and a fully armored knight was nearly invulnerable to whatever peasants could throw at them. But just a few short centuries later, no amount of armor humanly possible to carry could stop a musket bullet, so weapons were king, and armor got abandoned completely. Ironically the Peak Armor era was time when armor was already on verge of obsolescence, but it was easier to double down on old strategy instead of rethinking everything.

When tanks were introduced, a big reason they were quite successful was protection offered by their armor. Common infantry weapons just couldn't do anything to them, but of course that didn't last long.

As weapons got better, tank armor got heavier, and fast. First tanks to see combat in World War I had 12mm of armor.

By end of World War II, armor reached 250mm. To still be functional, it had to have far more compact shape.

It wasn't really possible to keep increasing the weight, and modern tanks aren't really much heavier than WW2 tanks, but using advanced materials to increase protection, the race between weapons and armor continued for a while longer.

Passive vs Active Protection

Right now it looks like the weapons are getting ahead. Armor is by no means useless, but in 2006 Lebanon War, Iranian anti-tank guided missiles were able to penetrate the most modern tanks just fine.

Weapons keep getting better, and it doesn't seem like armor has much space left to improve.

All militaries can see that, and they're equipping their tanks and other vehicles with active protection systems, which attempt to shoot down incoming missiles before they hit.

It's tempting to think that active protection is just another phase in evolution of tanks, but that's just wrong.

Tanks are the form they are because that's the only way to have thick armor while keeping weight reasonable.

Active protection has no such limitations. It doesn't matter if you install it on a tank, a light vehicle, or for that matter on an exoskeleton.

If active protection ends up being the winner, then mechs work just as well as tanks. And then liberated from just one form factor, we'll likely see a wide variety of different shapes of military vehicles - some might still look like current tanks, but others might very well look like mechs of various sizes, or something completely different.

And if active protection ends up being a big loser? Then giant mechs make no sense, but then neither do tanks.

Power Considerations

Another issues with mechs of all sizes is difficulty providing enough power and energy storage for them. Right now tanks are just more efficient, and mechs and exoskeletons are not very practical.

Fortunately for mechs, battery and engine technology is improving at very rapid pace, so it's entirely reasonable to expect this issue will go away soon.

There are even ways to recharge from air or space without any physical contact.

Future Prediction

In our world, it's very likely that exoskeletons will become widespread over next few decades, just like drones before them.

It's also very likely that active protection systems will increasingly become main protection. This will likely mean future tanks becoming lighter, as all that heavy armor just won't matter all that much. Wider variety of (mostly autonomous) military vehicles will come into widespread use, with very few relying on heavy armor, and most on active protection, stealth, or just being really cheap and expendable like most types of current drones.

Giant mechs? That's more farfetched for now, but if we have this discussion in a few decades, at time when most armies consist of exoskeleton-clad infantry supported by drone swarms, this really won't sound that far outside realm of possibility.

So if even our world is on verge of having mechs, it's just ridiculous to think there's no place for them in any sci-fi world, where technologies might have developed along different lines, and trade-offs are different?

The "tanks are always superior" crowd is going to sound just as ridiculous as believers in eternal superiority of heavily armored cavalry were a few centuries ago.

The real cost of oversized military

In one of my previous posts I pointed to the elephant in the room - Greek economic problems are largely due to its oversized military - this confused people a lot.


Let's do some calculation, pulling all assumptions out of Google. These numbers are actually very noisy year to year, but let's just take some long term average.

• Annual economic per capita growth 2.1% - this is world average since 1950
• Annual population growth - 0% - most developed countries we speak about here have little in terms of population growth
• Annual economic growth - 2.1% (by two above) - this number might seem low, but that's the facts, and there's not much we can do about it
• Starting debt level - 50% GDP - fairly typical for a developed country
• Interest on debt is 3% above inflation. This I base on historical rates of series I federal bonds before the recession, and adjust it a bit because most countries are less safe than States, so would need to pay somewhat more.
• Baseline size of military is 1.7% GDP - EU average
• Budget has 1% surplus before paying interest.
• This results is interest payment of 3% (interest on debt) * 50% (debt to GDP) = 1.5% GDP.
• This leads to deficit of 0.5% GDP.
• Because economy keeps growing - 0.505 / 1.021 = 0.4946 - so debt level will very slowly fall as percentage of GDP even as total debt keeps rising.
• Over 50 years, debt will fall to just 16.3%

This is all very reasonable. Now let's assume this country decided to have Greek style ridiculously oversized military - 4.3% of GDP. This is extra 2.6% spending. What happens in 50 years? Their debt grows to  175.5%.

Assuming anybody was still stupid enough to lend them money at the same rates, oversized military costs them 2.6% GDP (original spending) + 4.78% due to excess interest relative to baseline scenario. Imperialism costs far more than it seems to - and it has been a very long time since anyone made big money on empire building - usually the only benefactors are bankers and arm manufacturers in countries not engaged in hostilities.

A few inb4s:

• This reasoning applies only to excess military spending.
• Normal civilian government spending is typically useful, and if government slashed spending on healthcare, education, pensions, disability insurance etc., people would simply buy more or less as much of such services on private market.
• Even worse - if government slashed spending on research, basic infrastructure and so on, where benefits are diffuse, it would be very likely that nobody would pick up the tab, and it would hurt the economy significantly.
• Yes, there is some outright waste in civilian government spending, but similar waste exists in private sector as well.
• Baseline scenario already includes EU average military spending - and even if you argue that optimal level of military spending is higher than 0% (something I won't be arguing one way or the other now) - I cannot imagine in what kind of bizarro world EU average is far below the point of rapidly diminishing returns.

I'm not done yet. Let's assume interest rates are not constant, but vary depending on country's prospects. So at 0% debt you only need to pay 1%, then it grows linearly to 3% at 50% (like in scenario), and so on. There is some evidence this growth might be ever faster than linear, but let's stick to that.

• In 50 years of baseline scenario debt diminishes to 6.35% and nobody cares any more.
• In imperialistic scenario, debt after 10 years is only 73.43% (as opposed to 70.89% with constant interest rates) - it doesn't make a big difference yet.
• In 20 years debt reaches 110.62% as opposed to 93.7% - it start to get ugly.
• In 30 years debt increases to 189.96%, as opposed to 118.61%, but the glorious Greek empire keeps borowing.
• In 40 years debt reaches 531.73%, as opposed to 145.79%, and the interest rates are completely ridiculous over 22% per year.
• When the imperial scenario ends in 50 years, debt stands at 738747192.9% GDP, interest rates are almost 5% a day, and everybody is looking for the new suckers into this Ponzi scheme.

Of course Greece had to either collapse or change its ways long before that happened.