Strafe vs. bunkers?

[rocketman]

Is there any chance of a Spitfire strafe run to penetrate concrete bunker walls?

[John Kettler]

rocketman,

Unless the crew's sunning on the roof or nearby, or the Spit flies straight at the embrasure so low the prop's practically plowing the ground, I doubt it. As for whether you can frang a concrete bunker by strafing it in the game, I doubt it, but I don't know. Now, if you hit it with a 60 lb rocket... Oh, that takes a Tiffie.

Regards,

John Kettler

[Vanir Ausf B]

20mm sounds a bit light to be penetrating bunker walls. Unless the roof is considered much thinner than the walls you're probably wasting ammo.

[SlowMotion]

In one scenario I noticed that bunkers seem to be real tank target magnets.

There was one concrete bunker that probably had nobody alive inside, yet my tanks kept using ammo to totally destroy it turn after turn.

[Vanir Ausf B]

That is probably because the game engine classifies bunkers as a type of vehicle, so tanks will keep at them until destroyed just as they will an abandoned but operational tank.

[MikeyD]

What aircraft have is volume of fire. An fighter aircraft firing on a bunker would be something like a .50 cal quad firing. The chance of at least a few rounds finding an opening and hurting someone should be pretty high. I haven't tested it out but I'd expect casualties if not outright KO.

[Michael Emrys]

If they are waiting for a bunker to burn, it's going to be a long night.

Michael

[YankeeDog]

What aircraft have is volume of fire. An fighter aircraft firing on a bunker would be something like a .50 cal quad firing. The chance of at least a few rounds finding an opening and hurting someone should be pretty high. I haven't tested it out but I'd expect casualties if not outright KO.

Not really. Pillbox embrasures are specifically designed with large, thick concrete overhangs to block plunging fire. The plane would have to make an approach low enough to clip the grass with the propeller tips to have any reasonable of getting rounds through the slit.

Theoretically, I suppose it might be more possible in special situations, such as a pillbox on top of a hill with lower terrain to the front that would make it easier for the plane to approach at more or less at the pillbox's level. But in most situations, I'd say any pilot attempting this would have a better chance of taking himself out via controlled flight into terrain than he would of taking out the pillbox.

Never tested this in the game, mind you. Never occurred to me to even attempt it.

[Cuirassier]

Not really. Pillbox embrasures are specifically designed with large, thick concrete overhangs to block plunging fire. The plane would have to make an approach low enough to clip the grass with the propeller tips to have any reasonable of getting rounds through the slit.

Theoretically, I suppose it might be more possible in special situations, such as a pillbox on top of a hill with lower terrain to the front that would make it easier for the plane to approach at more or less at the pillbox's level. But in most situations, I'd say any pilot attempting this would have a better chance of taking himself out via controlled flight into terrain than he would of taking out the pillbox.

Never tested this in the game, mind you. Never occurred to me to even attempt it.

Indeed. Point hard targets do not become viable targets for aircraft until the advent of PGM's and modern targeting systems. I'm sure a Spitfire wouldn't even register as a threat to the crew of a pillbox. Just spotting the thing from the air with Mark I eyesight would be tough, let alone actually getting bullets through the embrasure (and those doing any damage if they do find a way through. Overall, its a poor, poor weapon for the job. It should be fighting Bf-109's and maybe strafing the odd truck convoy, not chipping concrete away from a pillbox roof. Leave pillbox busting to direct lay artillery and armor.

[rocketman]

20mm sounds a bit light to be penetrating bunker walls. Unless the roof is considered much thinner than the walls you're probably wasting ammo.

They do have .50 cal AP ammo - atleast in MG-module.

[JasonC]

Volume of fire and speed work at cross purposes.

Suppose the fighter is traveling 300 miles per hour and the bunker present a 5 meter cross section to its path of flight. Further suppose that is carries 6-8 50 caliber machineguns with a cyclic rate of fire of 480 rounds per minute, and all of them are firing as the plane sweeps that 5 meter cross section at that speed. How many bullets will be fired in the time interval when the fighter it actually pointing at the bunker?

The answer is 2. Actually 1.8 to 2.4 depending on whether you have 6 or 8 50 cals.

Now, if you don't have that much relative speed because you are pointed straight at the bunker (though that means you are about to hit the ground rather hard) then you can get more, to be sure. But the point is strafing is spreading the available bullets out in a very long ground footprint, precisely because the plane is moving so fast. There just aren't that many per unit of length on the ground, because there is too much ground covered in the short firing time, with all that speed.

If you are hitting a light aluminum airframe of delicate machinery that needs everything working to stay in the air, well, a few heavy hits will do something. But a lump of steel reinforced concrete weighing fifty plus tons just lying there?

People vastly overestimate the ground attack effectiveness of aircraft because their intuitions about distances, speeds, rates etc are just very far from being correct for the figures actually involved with warplanes. Smart weapons changed that; before them there was a lot of sound and fury and not a heck of a lot of impact on the ground.

[Vanir Ausf B]

I know. But if the 20mm won't penetrate what chance does the .50 have?

[rocketman]

Thanks for the insightful reply JasonC.

[YankeeDog]

I agree with your basic point Jason, but I will contest you on some minor points:

...suppose that is carries 6-8 50 caliber machineguns with a cyclic rate of fire of 480 rounds per minute,

Your estimate of cyclic is low by a good 40%. Pretty much all U.S. WWII fighters carried the AN/M2 version of the .50 Browning, which had a cyclic of 750-850 rnds/min. Most aircraft weapons of equivalent caliber from other combatants were similar.

Now, if you don't have that much relative speed because you are pointed straight at the bunker (though that means you are about to hit the ground rather hard) then you can get more, to be sure. But the point is strafing is spreading the available bullets out in a very long ground footprint, precisely because the plane is moving so fast.

Different strafing techniques were used in WWII. Your calculus assumes a linear-type strafe, where the pilot would trim the plane to fly in a slightly nose-down attitude, and then maintain a constant altitude of usually around 100m while he passed over the target. This yielded a long, linear area of effect. Very effective against spread out targets, such as airfields and road convoys.

But a pilot could also make a diving strafe attack, starting from an altitude of usually 1-2,000m and diving in at an angle of 15-20 degrees, pulling up at about 300m. This kept most of the rounds within a pretty small area, though there was still usually a "walk-up" and a "trail off" at the ends of the strafe attack. Good pilots could usually get 2-3 seconds of fire into a pretty small area with an attack like this.

So, with a diving strafe attack, you're probably looking at something like a couple dozen rounds impacting a 5m x 5m ground footprint, not ~2. This explains why strafing runs could cause considerable damage to un- or lightly armored targets like truck convoys, unarmored ships, etc. But this higher number of hits on a well-protected target like a bunker is pretty much moot since a .50 or 20mm AP round has no chance of penetrating 2+ feet of reinforced concrete, and only a one-in-million ricochet has any chance of getting inside the bunker through the aperture.

EDIT to add: And, as previously noted, of course this all assumes the pilot is actually able to spot a (usually well-camouflaged) bunker while racing around the sky at 300+mph. Even if a FAC on the ground was giving the pilot precise information as to the location of the bunker, and we assume the use of targeting aids like colored smoke, the vast majority of the time I doubt the pilot would be able to make a hard ID of the bunker. At best he'd be able to determine the approximate location based on the FAC's directions and the smoke or whatever, and then make a SWAG as to where to target the strafe attack based on that.

[JasonC]

YD - fair point on the ROF, I am much more familiar with the ground and pintel M2. Alone it increases the expected hits from a P-47 to all of 4. I looked up what it would be for a Spitfire V model with 2 20mm cannon and 4 .303 machineguns, and I get just under 1 20mm round and just under 3 .303 caliber MG bullets. Not a lot, really.

As for a diving attack, of course I mentioned that in my original post. They still result in lots of dispersion, along the axis of the run especially, but also in the other two directions. I agree it is even more fanciful to expect the pilot to pick up the bunker target on the ground.

The comment I was responding to imagined that with so many fast MGs or autocannons all firing at once, that the target would be inundated with streams of lead like something out of a Rambo movie, and that some must find the firing slits. And that just isn't remotely the case, for any of the figures under discussion.

The actual battlefield performance of fighter bombers doing armed recce over Normandy is something we know quite a bit about. Contrary to the picture one gets from flight simulator games or for that matter from CM, it was pretty dismal, against anything but soft transport targets. Trucks, wagons, railroad rolling stock - those were damaged in appreciable numbers. The fighters themselves were also lost in very high numbers.

In fact the average box score of an Allied fighter bomber in the Normandy campaign was about 3 soft vehicles *claimed* - and likely more like half that or less actually destroyed - for each fighter lost. Not per sortie flown, mind, but over the entire operational life of the fighter plane until it was lost to ground fire or accident, or both in combination (failure to make it home after battle damage etc). For armor, the exchange rate was something like 50 to 1 against the planes. Meanwhile, the average German Flak weapon system sent to the theater, heavy or light, accounted for multiple fighters.

Again people are overly impressed with the apparent power conferred by controlled rapid movement and possession of an initiative. The reality was instead that fighters did their most important work clearing the skies and thus letting transports operate in the channel in safety, and the like. As killers of stuff on the ground they were exchanging expensive warplanes for inexpensive Flak ammo and a few trucks. They doubtless still had a morale effect on the Germans, but in pure material exchange terms they were a very inefficient weapon system.

[SlowMotion]

AFAIK allied planes frequently searching for vehicles from roads also forced Germans to do much of their transportation during the night.

[JasonC]

Sure, they slowed marches to the theater, they spotted for artillery, they helped a lot in the pursuit after Germans had to pack the roads in daylight, the hurt German morale - air superiority is helpful, we get it. But they didn't kill much on the ground for the amount they lost, let alone the amount invested in the whole arm. The picture people have of their impact was already overrated at the time, and improve air to ground weapons since have only increased that impression. But a lowly 20mm Flak with one barrel was more likely to kill one of them than the other way around.

[SlowMotion]

I read a book of Apache pilot's experiences in Afghanistan. One of the chapters described a duel between his Apache and a Soviet made 2 x 20mm Flak. Their fight lasted quite a while and the Flak gun almost won it. So that caliber weapons can be deadly even against modern weapons.

[John Kettler]

SlowMotion,

If the Apache's in the 23mm's envelope, and if the gun engages first, especially if the Apache has nowhere to go quickly to hide, then it's really exciting. Contrariwise, if the Apache knows the gun's out there and where, then it can stand off and blow it apart at will. In Gulf War 1, an Iraqi farmer was much ballyhooed for downing an Apache. With an old Brno. In fairness, that was a a full rifle cartridge, not an intermediate AK-47 round, so packed more energy. Turns out Pentagon embarrassment was unfounded. The farmer found the downed bird and dead crew in his pasture. The rest was a brilliant piece of Iraqi propaganda.

In a larger sense, though, winning in the AAA game isn't what some might think. Ideally, AAA forces the attacker to give up altogether, aborting the attack on the defended assets. Failing that, it seeks to degrade the attack and inflict an entry penalty on the attacker. Anything over a 3% sustained loss rate will completely eviscerate air units. Losses are taken not only over the target, but en route home and in crashes once back home. And of those, many will never fly again. As for an actual shootdown, when did it occur and at what price? Did the defended assets get smoked, and the kill was obtained on the egress phase of the attack, or did the kill come before the attack could be mounted. Big difference there. I don't know how detailed that sort of damage to aircraft modeling is under the hood, but in the real world, such things matter.

Regards,

John Kettler

[poesel]

... The picture people have of their impact was already overrated at the time, and improve air to ground weapons since have only increased that impression....

Sometimes the impression of being dangerous is enough - especially if the enemy has that impression.

[womble]

Getting the AAA game sorted is going to be even more crucial in the "Black Sea" game, given the increase in relative power and effectiveness of the air arm in the decades since WW2. I suspect the only way to handle the wider effects of air defense nets is through purchase costs; giving inbound air support a chance to be shot down/aborted by long range SAMs would probably get put in the "liable to frustrate the player too much" column.

[SlowMotion]

In a modern game you can't forget shoulder launched AA missiles that could be placed anywhere on the map and things like Shilkas. Both very nasty to helicopters at least.

[JasonC]

On Apaches, helmet mounted sights and stand off range guided missiles - not the same match up. And yet, in the first phase of the second Iraq war, when the 101 tried to pull a vertical envelopment in line win airland battle doctrine, they got a quarter of the entire division's attack helos grounded by damage in less than 12 hours, and had to call it off. From small arms as well as heavy MGs and light flak. Meanwhile, a column of M-1s and Bradleys on the ground had no trouble going straight through the defenders, faster than the 101 could in practice afford to go over them.

Ground combat power is underrated and air overrated, even today. But WW II air, there is no comparison.