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Tobba_ | 7 years ago

The idea of drone swarms doesn't go well together with aerodynamics and basic physical intuition. If you shrink an aircraft down, the aerodynamic cross-section (i.e the drag force) scales with the area (scale^2), but your engine thrust is going to drop roughly by the decrease in volume (scale^3).

So you end up losing maximum airspeed and fuel efficiency (in terms of the mass you're moving) the smaller you go. Unless the drones in your swarm were really big, it doesn't work out.

Although, I imagine we'll see some smaller, unmanned jet fighters in the future (assuming someone figures out how to control something like that remotely, or autonomously). A smaller aircraft has the advantage of a smaller radar cross-section and being more difficult to hit. Doing away with the pilot cuts out a lot of weight and frees up room for a larger engine and fuel tank, offseting the downsides of the smaller size somewhat. There should be a sweet spot where that works out.

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sawjet|7 years ago

Shape is the major determining factor for radar return, not size. From Ben Rich's Skunk Works-

>I really wanted a photographer around for historical purposes to capture the expression on Kelly’s big, brooding moon-shaped mug when I showed him the electromagnetic chamber results. Hopeless Diamond was exactly as Denys had predicted: a thousand times stealthier than the twelve-year-old drone. The fact that the test results matched Denys’s computer calculations was the first proof that we actually knew what in hell we were doing. Still, Kelly reacted about as graciously as a cop realizing he had collared the wrong suspect. He grudgingly flipped me the quarter and said, “Don’t spend it until you see the damned thing fly.” But then he sent for Denys Overholser and grilled the poor guy past the point of well-done on the whys and hows of stealth technology. He told me later that he was surprised to learn that with flat surfaces the amount of radar energy returning to the sender is independent of the target’s size. A small airplane, a bomber, an aircraft carrier, all with the same shape, will have identical radar cross sections. “By God, I never would have believed that,” he confessed. I had the feeling that maybe he still didn’t.

trhway|7 years ago

>with flat surfaces the amount of radar energy returning to the sender is independent of the target’s size.

it is basic geometry. Like a flat mirror, no matter the size, will reflect to you the same Sun spotlight (to be precise - as long as the mirror is bigger than 32 arcminutes as seen from the receiving position)

engi_nerd|7 years ago

Yup, shape is the biggest thing you can control, then radar absorbing and reflecting materials.

One of the big anecdotes from the early days of stealth aircraft development in the 1970s is how at some wavelengths the Hopeless Diamond shape wasn't visible to range radars at all. During one test, the range radar guys went absolutely crazy trying to detect the shape -- which was a pole model, not even flying yet -- and were about to just give up, when suddenly, there it is on their screens, plain as day. Awesome, the Hopeless Diamond lost its stealth! Or not, because what really happened was a bird landed on the pole model.

That's the power of your aircraft's shape.

Someone1234|7 years ago

> If you shrink an aircraft down, the aerodynamic cross-section (i.e the drag force) scales with the area (scale^2), but your engine thrust is going to drop roughly by the decrease in volume (scale^3).

Why would we shrink drones down? You read drone swarm and assumed small, but most swarm proposals are using drones of a similar size as today or even large in some cases. They're swarms because of the way they interact with one another, and overwhelm enemy defensive systems, not because they're small.

cameldrv|7 years ago

Yes, but the parasitic drag scales with velocity squared, and the induced drag scales with mass. Shrink the aircraft by 2 in all dimensions, you're fine on induced drag, you just need to slow down by a factor of 1-sqrt(2) -- 30%. Structural weight will also be much less. You also aren't carrying the weight of a pilot cockpit, ejection seat, etc. You don't have the drag penalty from the canopy either.

You do need to duplicate a lot of systems, but with modern electronics, these are a lot lighter and take much less power than before. The swarm aspect also allows for large synthetic apertures instead of a big single radar aperture in the nose of one aircraft. Swarms can also deploy cheap unguided weapons, because they can get very close to a target without the worry of losing a pilot and a $100 million airplane. The structural advantages of being small can also be exploited in an unmanned vehicle in that they can sustain much higher G loads than a large airplane, and with no pilot to black out, they will be much more agile in evading missiles.

Tobba_|7 years ago

"swarm" means large numbers by definition, otherwise you have... well, plain-old coordination. Large numbers of F-35-sized aircraft is flaunting economics in the face a quite a bit (so I'm sure the US military loves the idea).

tlb|7 years ago

Aircraft drag is largely from the wings producing lift, which scales with weight (l^3).

The drag from the fuselage does scale as l^2, but most drones have small fuselages since they don't need room for a pilot and (for fighter planes) a big glass canopy, and lifting drag dominates.

pfschell|7 years ago

Your comment assumes "drone" means anything like we have today. Any fighter designed in the last 40 years could be made substantially better by removing the pilot and everything necessary to keep him alive and in the fight.

browsercoin|7 years ago

How would manned fighter jets counter an adversary like in this video?

https://www.youtube.com/watch?v=CGAk5gRD-t0

You can see the swarm of drones that could absolutely wreak havoc and out pilot humans with AI advancement.

tim333|7 years ago

That drone swarm is dropped from a fighter and they don't go very fast or probably have much range. The was to defend would be to stop the fighter flying over your target. I'm not sure it dropping drones would be any more effective than dropping guided bombs in the traditional way.

noobermin|7 years ago

When in the near future are we going to need drone swarms for anything?

erikpukinskis|7 years ago

Defending from attacks by terrorist drone swarms?

m1573rp34130dy|7 years ago

doing away with the pilot also allows the air craft to execute extreme maneuvers that would instantly kill a biological pilot inside...