Actually no.
Due to flying at 1/10:th of the speed of a jetfighter they can fly 10 times closer to the ground (due to having 10 times more reaction time). All aircrafts become impossible to detect on radar no matter how advanced if there is a hill in the way. A small cessna can fly below the horizon until the very last moment, unlike anything travelling faster could.
There is also the issue of stall speed, a small airplane can fly many times slower then a jet airplane can.
Due to being so small, a Cessna is also likley to have at least half the cross section of a larger jet airplane. Combined with the above it should mean that the low flying cessna is about 5-20 times harder to detect on radar then a low flying (non-stealth) jet airplane. Meaning they can get that much closer before being detected.
On the other hand since they are so slow radars have plenty of time to refine the picture, making it fairly easy to spot them. Remember, most of our current systems were developed to detect near supersonic jets flying just above the trees and attack helicopters flying below them.
Additionally, many LW civilian planes of the type you seem to have in mind are deliberately designed to be highly visible on radar, in order to make air traffic control easier.
Far from all airbases are defended by advanced radarguided AAA cannons. Especially ones that can be made ready at moments notice without previous warning.
True, but the ones within range of the type of strike you're talking about are. (See Kandahar airbase in Afghanistan for an example)
I wasn't talking about a general warfare tactics, but more off a surprise raid tactic that could well work against airbases once or twice, but not really in the long run.
We're well aware of that, but it's a moot point since the type of airfields you could attack tends to be within friendly territory. Good luck trying to sneak a dozen planes in, let alone a couple of hundred.
Even assuming the radars are blind as bats you'll in all likelihood be found by your radio chatter. Even with the best of planning you'll still need to coordinate the strike on-site since you won't have the chance to rehearse it.
My main point is that at $500 million for an F22 (including development costs) you could afford 4000 say Cessna 162s for each of them. Now add explosives and remote controls and you might still afford 2000 off them. Or just add crazy terrorists that don't mind suicide missions but feel like hitting a military target this time (which would actually mean they are not terrorists, but anyways...)
Again this is a moot point because you're never going to be able to launch any kind of mass strike.
You also assume that these planes are left standing around in the open. Surprisingly, they're not. In peace time they're stored in hangars, which makes hitting them pretty hard since you won't know which one to hit (Not much point in hitting one that's filled with Cessnas)
In wartime they're relocated to hardstands. This is airforce lingo for bunkers. You know, the buildings designed to resist actual armour-piercing bombs.
Even if a modern airbase only has a few off these ultra expensive airplanes a low tech surprise strike through numbers could very very quickly overwhelm any defenses for a fraction of the cost off the airplanes destroyed. Any guerilla or insurgency fighting US forces today is ready to take hundreds of losses on the ground already, why would high risk missions in the air be any different?
Because it takes a whole lot more planning and training. First off you have to actually get all the planes. How would you even do that? Even mass produced ones like the 165 isn't made in that huge numbers and some intelligence character is bound to ask question if someone started stockpiling them. Then you have to teach them how to fly, which means you'll need instructors. And then you need to train for the actual raid. Compared to this, training an insurgent involved finding a likely person, buying an AK and a couple of grenades for him and take him into a large basement and let him shoot of a couple of mags at a target.
I'm not saying any attacks should involve hundreds or thousands of airplanes, just that you could take these kind of losses and as a weapon kind it would still be cost effective if it can knock out a single F22...
It'll never be cost effective so long as it doesn't work. Which is doesn't.
It doesn't matter how quickly a phalanx would tear through a Prop airplane, they can still only fire for less then 20 seconds anyways before they are out of ammo and are 100% useless for the next 5 min while reloading (assuming reloads are even close at hand). In a WW2 situation any AA gun spending 93% of the time reloading would have been regarded as useless, you would need a battery of 15 guns taking turns to have full AA cover in a situation where the sky is filled with enemy airplanes.
True, if you were dealing with a single layered defence and you were flying mill-grade aircraft.
However, you're dealing with a multi layered defence and you're flying incredibly fragile piston engined (with all the associated fire hazards) aluminium cans filled with explosives.
Simple assault rifle fire will suffice to kill you, a single 20mm round will pull the engine out through the tail.
Oh and and you're going to need a
lot of explosives since you can't count on actually crashing in to them. This will cause your aircraft to be extremely heavily loaded and ungainly.
SAM won't work at all since they come in two kinds:
1.) Radar guided which have a mimimum engagement range and are meant to hit high flying bombers or ballistic missiles (Aster in Airbase defence role for example can't engage targets within 3000m).
Roland, Super Hawk, SeaSparrow and Sea Wolf disagrees with you. (Okay they do have minimum ranges, but they are measured in tens of meters, not hundreds, let alone thousands)
2.) Heat seaking, Stinger style that are guided by the hot exhaust off a jet engine (you would be more likley to hit a nearby Humvee then the heat signature of a 100hp Cessna engine).
Ever seen those police shows on the tellie where they chase the crook with a helicopter? Notice how he lights up like a Christmas tree compared to the background? The same technology that makes that possible is used in IR guided missiles. Now, instead of a scant 10 or 20 degrees celcius in difference you have about 100, so targeting should not be a problem. And indeed it isn't. After all, the drones they train against are essentially remote-controlled cessnas.
You do mention stationing 100:eds of soldiers with HMGs in a wide perimiter, which would ofcourse work fine. But this is not something that is in place at any airbases today which means they are vulnerable to the element of surprise attack. Currently those few HMGs are pointed towards the access roads in case a insurgency truck loaded with explosives would show up...
Funnily enough, the layout of defences are one of those things the various militaries all agree on shouldn't be shared, so we don't actually know how places like Kandahar is defended in detail. So we don't actually know if those defences are in place or not.