Is there an available study somewhere on the effectiveness of WWII Tactical AAA; i.e., the weapons usually found mounted on half-tracks?

Thanks in advance.

Some quotes from my book 'Rapid Fire: the Development of Automatic Cannon, Heavy Machine Guns and their Ammunition for Armies, Navies and Air Forces':

"The evaluation of heavy machine guns was rather confused. They had proved largely ineffective in the AA role. An American analysis based on the last year of the war showed that over 50,000 .50" rounds were fired for every aircraft brought down, compared with 500 Bofors rounds; that is, almost two hours of continuous firing per gun, compared with four minutes."

and:

"Curiously, the British Army showed little interest in light cannon, rapidly abandoning the various 20mm guns for improved models of 40mm Bofors. This view was probably influenced by operational research into the relative effectiveness of the 20mm Oerlikon and 40mm Bofors in dealing with low-flying coastal raiders. It was noted that these were not usually spotted until 1,500 yards (1,370m) away, so the Bofors could not use its range advantage. Engagement times were only about 13 seconds (from first sighting the target to the last shot) and the Bofors only had time to fire seven or eight rounds to the Oerlikon's 50. Even so, in most circumstances the Bofors was more effective.

Calculations were made about the probability of success (immediate break-off, or eventual crash) against a Junkers 88. Using simple sights only, the Oerlikon's chances were estimated at 3% against a crossing target, 12% against one approaching head-on; the Bofors' 18% and 20% respectively. With more advanced sights, performance was much better. Using predictor control, the Bofors' success rate rose to 35% and 39%. The addition of a Triple Gyro sight had an even more dramatic effect on the Oerlikon's performance – to 17% and an astonishing 76% respectively."

Tony Williams: Military gun and ammunition website and discussion forum

Tony, I just finished a book on Anti Aircraft Command 1939-55 The Other Forgotten Army by Anthony J. Cooper. He mentions some 40mm being replaced by multiple 20mm during the low-level hit and run phase of attacks on UK coastal towns in 1943. These were deemed more effective due to the lesser amount of warning time you got with an incoming single engined plane approaching at low level. Presumably that was before the operational analysis you mention was undertaken.

Have you got any detail on how those American figures were arrived at? My only experience of shooting at aerial targets is clays and birds, but we have several people on the island that effectively wing shoot ducks with .22 long rifles (this started here long ago due to .22LR ammo being much cheaper than shotgun). I think clays were part of the training given to US AA gunners along (air powered BB machine guns were also used to train air gunners).

I think the massive number of rounds may be partly due to the fact that the .50s were fired by personnel that weren't specialised or trained sufficiently in AA fire or were firing for deterrent purposes rather than with any real hope of hitting.

Don't know any figures, but German low level AAA with their 20mm and 37mm guns were highly respected; when Finns and Germans turned to each other in 1944, FAF immediately noted high effectiveness of German AAA and losses were heavy considering low amount of sorties. Similarly, I understand that low-level Flak took a heavy toll amongst Allied fighter-bombers right to the end of war.

I seem to remember being told of testing the poor state of RN ship flak . A target was towed around the ships for ages and the ships were never able to hit this (?)

Any one ever heard any more details on this test.

I wonder when the US Army would have fired large multiples of 50k rounds at airplanes from the ground in actual combat late in WWII to get a good statistical sample. Anyway the USN concluded .50 was a pretty useless AA caliber early in the war; although it's not quite the same situation defending a high value target like a ship, and when a .50 doesn't really have other roles (in a WWII shipboard setting) whereas it does on land. The US quad .50's were effective ground weapons in WWII, then especially so in Korea (and a keystone of the final series of French positions at Dien Bien Phu was a couple of towed lightweight quad .50's, M55). Though you can shoot 40mm at ground forces too, the quad .50 seems to have built a special reputation for that use, with some AA capability "for free" (more or less).

20mm, even with on-mount lead computing sight as std later in war was judged mainly useless on ship by 1945. When those started firing against a kamikaze attacking DD's off Okinawa it was said to be the signal to shut down the blowers to the engine room to avoid injesting flame when the plane hit.

But again depends on the threat, whether attrition/distraction of the enemy planes is sufficient, or they must be stopped each time, and what special diversion of resources the AA gun represents. For another example The DShK in Korea and Vietnam has to be judged a highly cost effective multipurpose incl AA weapon, I think.

Joe

The consensus between Il-2 pilots seems to be that in the first half of the war, the main danger were enemy fighters. In the second half, the risk from fighters fell waaay down, while AAA, specially medium caliber (usually referred as "oerlicons"), rose waaaay up.

Al - I assume you mean the M15 and M16 MGMCs issued to SP Anti Aircraft Autoweapons (AAA) units? As some posters have already pointed out, the .50 BMG was a pretty poor chambering against aircraft. While it is effective in terms of ballistic performance, it's lethality was very poor against the German attack aircraft of the day such as the Fw 190G. Thus while it might riddle an aircraft and cause it to abort, it simply lacked the wallop to knock them out the sky.
The M16 and M55 Maxson mounts were actually far better employed in ground fire and they earned a ferocious reputation for this.
The M15 and M15A1s employed a pair of .50s matched with a 37mm M1 gun. The latter was significantly less capable than the L60 Bofors. In the pacific they extemporised a Bofors onto the M15 as the M15 Special.

Indeed later war ground attack aircraft were very robust and heavily armoured. The Germans found that their 20mm Flak 30/38s (Solothurns rather than Oerlikons) were increasingly ineffectual against aircraft like the Typhoon and Thunderbolt. Even the Falkvierling quads were not considered to be adequate, which is why they went to the 37mm FlaK 43 as their 'desired' late war light AA piece. It would replace the Vierling on the MkIV Flakpanzers on the Ostwind and it was the standard armament for the Mobelwagen (Tamiya's 20 year gaffe not withstand). The FlaK 43 combined a high cyclic rate with the hiting power of the 37mm round of the Flak 36 and was a serious threat at low-altitiude.

The Germans however ran into increasing production difficulties with their highly engineered Refleksvisier (reflex gun sights) and went to the simpler Flakvizer ring type sights, which were a retrograde step but essentially what everyone else was running.

The measure of the failure of both the .50 and 37mm M1 can be measured by the fact that they were replaced at the war's end by the M19 MGMC mounting a pair of 40mm L60 Bofors. The end of the war cut into the reequipment process and resulted in hybrid M16 and M19 units fighting in the Korean war. Both proved exceptionally effective at breaking up infantry attacks and would play crucial roles in battles like Chipyong'yi (I can't spell these things)

Simon

I subscribe to the theory that the purpose of AAA (like bomber defensive armament) is just to make the enemy planes fail to accomplish their mission, not to shoot them down. If a plane takes a couple .50 hits, breaks off the attack and returns to base, the AAA wins.

Also, this is the same .50 that, on US planes, hacked FW190s out of the sky in considerable numbers, so I'd be careful about lethality assumptions.

Ballistically, the .50 was probably the equivalent of the 20mm, which also required multiple mountings, preferably powered, to be effective.



There were an interesting variety of AAA projects that never made it with the US. , including IIRC a quad .60 turret on the M24 chassis. Late war the Germans were putting 15mm MG151s on half tracks in triple mountings so, while certainly their preference was for 30mm and up, even the Germans thought .50/.60 still had something to offer.

I thought the whole idea of the gradual movement from MG to Cannons in fighter aircraft, was due to the inadequate killing power of machine guns. A single hit from a 30mm API, could cut a fighter in half.....Besides isn't the MG151 a 20mm cannon?

RE Heavy Flak, I read somewere that in 1943 roughly 3500 x heavy flak shells [88/105mm] were required to 'statistically' bring down a 'plane' flying over Germany.

Not necessarily, considered in terms of fire-volume. Two or three cannon will certainly shred whatever they hit, but they have to hit; whereas 8 MG mounted in two wings will provide a pilot with a better chance of scoring at least one hit and probably doing something debilitating in the process.

To some degree size matters; British .303 MG had a hard time dealing with ME-109s, while the cannon from -109s did just fine against Spits and 'Canes. Keep the number of guns the same, though, and bump the size to .50 cal, and it's a different story. .303 is rifle ammo, .50 is not.

As aircraft became better armored the need to hit them harder became apparent, and eventually obviated the MG. Note however that in Korea Sabre pilots flew agains cannon-armed MiGs and in the final tally outscored the MiGs. Some Sabers were armed with cannon, but some were armed with MG.

Gun caliber certainly plays a role, so does the quality of pilot and/or plane.



There are apparently two weapons with the MG 151 designator. One is the MG 151/15, the other is the MG 151/20. Both are cannon, but one is a 15mm weapon and the other is a 20mm weapon.



Shot

The USN, which used both the .50 and the 20mm in aircraft, reckoned that the 20mm was about three times as effective as the .50. So the usual RAF quartet of 20mm was twice as effective as the usual USAAF fit of six .50s.

The superior performance of the Sabre was despite rather than because of its armament (although the MiG-15 was no better in that respect, as its armament was optimised for use against heavy bombers). Nearly all of the Sabres were equipped with .50s, but late in the Korean War the USAF combat-tested Sabres armed with 20mm cannon, and the result was such that they immediately switched to 20mm for all new planes thereafter. At the same time, the rest of the world moved up to 30mm...



Actually, according to the Germans, they were both machine guns rather than cannon, whgich is why they have the MG rather than MK prefix.

If you want to learn about WW2 fighter armament, read this: http://www.quarry.nildram.co.uk/WW2guneffect.htm

Tony Williams: Military gun and ammunition website and discussion forum

That's the crux of the matter. They would have been a small percentage of the total number of 0.50s that could have been trained at aircraft. The quad fifty could also be used dismounted - and post war often was. Many were used in Vietnam. I don't think that was the case with the 37+2 0.50s mount (which served as late as Korea)

The MG151 Drillings on the SdKfZ 251/21 were a naval mounting that was impressed into service on a simple free pedestal mount. While on paper they seem impressive, in reality the extremely cramped arrangements and solitary gunner made it a rather poor AA weapon. They were however better than the alternative, which for the gepanzert battalions was nothing heavier than a MG42 on the stern AA pintle.

Despite the 20mm calibre, the MG151 was in no way comaprable to the much larger FlaK 38 in terms of either ballsitic performance or lethality. The experience of Normandy pretty much drove the Germans to the conclusion that any AA was better than no AA.

The SdKfz 251 wasn't suited to mounting AAA due to the inwards slope of the upper armoured surfaces. The Germans did however make extensive use of the lighter DEMAG SdKfz 10/4 and heavier Hanomag SdKfz 7 as SP FlaK guns but these had unprotected flatbeds onto whicht he guns were mounted. The SdKfZ251/17 FLaK SPW was not very successful. The 'famous' Luftwaffe version had the flank armour hinged to open out to enable low-angle fire but there were precious few of these. The more common solution was a hybrid Kwk30 with FlaK 38 barrel on a pedestal, somewhat simialr to the Hanglafettes of the Radpanzer. This suffered from many of the problems that were to plague the Drillings.

The .60 HMG never went anywhere. It lacked the punch of 20mm cannon and the extra ballsitic eprformance just didn't make all that much difference. In fact the only >.50 cal weapon to have any success has been the 14.5mm KPV. It wasn't adequate by any means and was supplanted in the 60s by the iconic ZU-23.

Chris...you're thinking of the M55 Maxson ground mount. It goes on a trailer. I don' think the M16 units routinely dismounted the guns but I believe that M16 Maxson mounts may have been converted into M55s. These would wind up on 'gun trucks' in VN.

And of course the other way around. Prior to 6 June 1944 US Army Ordnance mounted 321 M55 mounts onto spare halftracks in England, enabling them to equip one SP platoon in each battery in nearly every AAA Automatic Weapons (Mobile) Battalion in the theater. My Dad commanded one of those platoons in Battery A, 537th AAA Battalion. I think those were eventually the source of the M55 mounts "converted" from M16, since the trailer minus its wheels had been simply bolted into place.

This is whacky because around the same time, the British Army was busy stripping >1,000 M14 MGMCs (twin .50 Maxsons) of their mounts to make into regualr HTs! They had little enough need for these since they were even busy disestablishing SP LAA.

Was the 537th a 'real' SP unit?...or extemporised? I always though the AAAs attached to Infantry divisions kept M55s and Bofors guns.

Any data for the Russian SPAAG in ww2? I just know that they where feared by CAS pilots of LuftWaffe and RRAF that flew HS129B's.

Thaks for all the great info guys. This is really helpful.

Couple of other points. I have heard that since the threat from the Luftwaffe was low, that AAA units were used to provide replacements for the infantry. Rather than just sending men, were any of these AAA units "broken up" & parceled out to line units? For instance, assigning a AAA battery to infantry battalions so they could be used in the ground support role?

Why was it "whacky" Simon? Those were British Army Lend-Lease vehicles, not US Army vehicles? And by this time the BA was pretty well equipped for the invasion with 20mm and 40mm SP AA, I can give you details if you are interested.




Nope, it was a "Mobile" battalion, not SP. Re-examining may stuff I find that the Automatic Weapons Battalions were organized as:

SP - four batteries, each of four platoons, two with 4 M15A1 each and two with 4 M16 or M17 each.

Mobile Standard TO&E - four batteries, each of four platoons, two with 4 40mm towed each and two with 4 M51 MG carriages (M55 was actually intended as an airportable mount and was in limited supply in theater).

Mobile Modified TO&E - four batteries, each of four platoons, two with 4 40mm towed each and the other two with either 4 M51 each or 4 M17A1 each (the theater-modified M5 HT with and M51 bolted onto the rear). There was a lot of variation, the 537th had A Battery with two platoons of M17A1 (my Dad commanding one of them), B and C Battery were the same, but D Battery had .50 caliber AA MG M2A1 (water-cooled) on Mount M2A1.

Semi-Mobile, organized as per the Standard Mobile TO&E, but with fewer prime movers.

Yes - the famous incident involving the Queen Bee - apparently, the "dive" command was eventually given, to simulate being shot down!

I have seen this referred to in many books, so it is probably not an apochryphal tale; alas, I can give no references at the moment.

Apart from the 12.7mm DShK, which was the equivalent of the .50 M2, they used automatic cannon derived from Bofors designs, in 37mm and 25mm calibre. See the article on my website on 'Bofors Automatic Cannon'.

Tony Williams: Military gun and ammunition website and discussion forum

Simon, post war the Dutch built a wide variety of fortifications as part of their Ijssellinie defence plan. Many of these structures used quad 50s. Those accessible by land (some were built into dams etc.) didn't have the quad mount permanently fitted - instead an AAHT would drive out and the gunners would take the mount off the HT and bolt it to a turntable inside the position. These vehicle gun mounts were apparently not the M55 with the tyres. The position even even had a sunken parking spot for the vehicle. Here is a model of one such position:

http://www.johannas-art.com/M16HT.jpg

I'm not suggesting this was routine in the ETO or that this happened in Korea or Vietnam. However, I'm sure that multiple mountings of all types would have been a small minority of 0.50s that would have been trained at attacking aircraft in most circumstances. Most would surely have been vehicle flex guns and single ground mounts. Some US Engineer units in england even put single water-cooled pedestal mounted fifties on the back of trucks.

AA Command was losing personnel and units from quite early in the war as the air threat diminished and other arms started to suffer personnel shortages. However, some SPAA was used in the Diver belt against flying bombs. Some SPAA tanks also made it to Normandy, although I believe some of the units that had the AA tanks left them behind during the subsequent advance. I'm sure Rich could clarify/debunk that though.

Except Dshk's was widely employed quad-mounted, liquid-cooled Maxim machineguns AA 7,62mm(.303). Together with Dshk's they officially claimed 512 aircraft kills. Typically, it takes 3 to 6 .50 hits to shoot down Bf -109 and 2-2,5 times more with .303.

Russians didn't have any SPAAGs in WWII. The only real SPAAG was rather unsuccessful ZSU-37 built on the basis of the T-70 light tank. Only 100 or so were built and they were not a success. Other than that there were some lend-lease halftracks with AA guns and improvised trucks with guns ranging from 7.62mm Maxim to 37mm 61-K.

Vladimir

Finland used the Swedish Landsverk Anti II SPAAGs which had a single 40 mm Bofors gun. Six of them were bought and they were used to protect the lone armoured brigade and managed to shoot down 11 aircraft and damage 7. Those were probably mostly Il-2s, but I don't know exact details. Pretty good score as they didn't lose any of their vehicles, but 4 men were KIA and 11 WIA. It was also very important that many air attacks were foiled and Shturmoviks didn't manage to destroy the armoured units. I think that Landsverk Anti II was probably the best SPAAG which participated in WWII. Of course the Swedes developed even better SPAAG in Lvkv fm/43. Some pictures and Swedish text can be found at :
http://www.pansarmuseet.se/lvkv43.htm

Yep, 100 M15 and 1,000 M17.

It took place in 1937 when a Queen Bee drone flew straight and level around the entire Mediterranean Fleet at a stately 85 knots and wasn't hit by a single shell. The problem, of course, was not the weapons, but the fire control system - the British High Angle Control System was flawed in concept and design and RN AAA suffered as a result.

My father-in-law was a radar operator aboard the USS Wright (CVL-49) late in the Korean War. He told a similar story of a drone flying unhit over the ship during excercises off Key West Fl. The gunnery officer thought it would be easier to hit if the drone was diving towards the ship!. The drone crashed into a gun tub, killing three, and the gunnery officer was taken off the ship that evening.

Thanks for the link. Interesting they had radio controled plane back in the 1930s.

If this target paraded for an hour and on 'flak' type gun could do 12 RPM thats ~ 700 rounds per gun. They must have fired thosands of rounds without any results.

The german 1943 example of 3500 rounds per plane shot down over germany presumably was from 'grossbatterie' I wonder what kind of fire control directors they had back then? I gather by 1944 the figure had climbed to 35,000 rounds per plane shot down. I wonder what changed to result is such a change in results?

"Flak" by Westermann is a pretty complete history of the flak arm. Rounds per kill varied a lot and he seems to admit that single undisputed figures even for a period of the war can't be certain. But some comparatives he gives are first 20 months of WWII: 2805 heavy and 5354 rounds of light flak per kill. Late 1943 4000 heavy and 6500 light. (Light presumably refers to national defense Luftwaffe light flak only).

He discusses what he says is often quoted 16,000 rounds per kill by 88mm in 1944. Among the reasons were basic gun v. plane performance; B-17's bombed from the edge of the Model 36-37's (always far the most common 88) effective envelope and were more common attackers in 1944 than previously. In contrast the relatively rare (never more than a small % of flak force) 128mm reqd 3,000 shells per kill in 1944. Also in 1944 degraded guns that needed barrel changes were more common, and Allied ECM continuously improved. For example by the fall of '44 most USAAF bombers had active jammers, before that pretty uncommon.

The Germans had a hi/lo flak mix where some batteries had no directors, were often captured weapons (like Soviet 85mm) and fired barrages w/o directors. But the more numerous standard batteries almost all had directors and fire control radars even by 1943; thereafter what level of ECCM upgrade against chaff and jammers made a difference.

For comparison to the 128mm ratio, USN 5" with VT in the same period had ratio's in the range of 60-240 rounds per kill for different conditions of range and day v. night engagements per Friedman. The ratio of VT to time fuze effectiveness was given as around 4 to 1. The naval gun targets were not directly comparable: easier to reach and employing less ECM (Japanese used no active jammers AFAIK, though did use chaff, and used passive receivers to approach along nulls in antenna radiation patterns at night, late war); OTOH typically smaller, faster and maneuvering less predictably.

Joe

I know this happened to some of the Canadian units in 1944, but we were going through the Great Conscription Crisis at the time, and many infantry regiments were manning the line at half-strength. Reinforcements from other support units were culled as well, many only half-trained, which resulted in a noteable increase in the casualty rates afterwards.

Some of our other LAA units were kept intact for ground support roles; interestingly, the barrel replacement rate for 40mm Bofors became a critical issue when firing 'pepperpot' missions - according to Blackburn, sustained firing caused the barrels to bulge. Still, I suppose they felt that they were at least doing something useful.

My favourite Bofors story comes from Johnnie Johnson's WING LEADER... a single gun on forward airfield defence shot down a strafing ME-109 with one round... the gun corporal asked Johnson to verify the kill as he said his own commanding officer would never believe it! Johnson promised to do that, and supplied a case of beer for the gun crew...

Is it true that early in WWII a single radar-directed shot destroyed a British bomber? I read (somewhere, Soldier of Fortune or a box of cereal) that this inspired Herr Goreign to claim no British bomber would ever attack the Fatherland.

One of the more interesting things the Germans did was experiment with impact fuzes for their heavy flak guns. The theory behind this was that the chances of putting a time-fuzed shell close enough to damage an aircraft was almost the same as getting a direct hit, and by using impact fuzes you would eliminate any error created by the time fuze, as well as increasing the rate of fire and shortening the time between calculation and firing. The scientists crunched the numbers, which showed that theoretically the impact fuze was far more effective than time fuzes, and sought to convince the LW flak experts to do firing trials - during combat trials in Munich heavy flak batteries during one raid shot down 13 aircraft with an average expenditure of 370 rounds per shootdown. In late March the Luftwaffe ordered the heavy flak batteries to use nothing but impact fuzes, but by then it was too late to have any affect.


Source: "German Artillery of WW II" by Ian Hogg

The terminology of calling unmanned aircraft "drones" comes from this system. The aircraft with a the remote controller on board would be "queen bee", and the remotely controlled aircraft was the "drone".

What always amuses me is that the people around at the time couldn't see the woods for the trees and never though of attaching a bomb to the Drone and using it as an anti ship weapon.

Twenty years earlier, they had done exactly that!

In 1915, the Navy appointed both Sperry and Hewitt to its Naval Consulting Board, and Sperry, as chairman of the Board's Mines and Torpedoes Committee and a member (along with Hewitt) of its Aeronautics Committee, had little trouble gaining Navy approval and funding that October to continue developing what had come to be called an "aerial torpedo." The aerial torpedo program was broken into two phases, the first to develop a gyrostabilized, bomb-carrying drone with a distance gear (i.e., a preprogrammed version), followed by the addition of radio controls for directing the torpedo from an accompanying airplane (i.e., a controllable version). The Navy's concept of operations was to employ the torpedoes against German U-boat bases and munitions factories from distances of up to 100 miles. Flight tests began in 1916 using Curtiss N-9 seaplanes with safety pilots in them to perform the takeoffs and landings, and by November, 30-mile flights with accuracy errors of 2 miles (400 feet per mile flown) were being achieved.

[snip!]

During these same years in Britain, the Royal Aircraft Establishment was also developing a cruise missile, working up to flight ranges of 300 miles before beginning tests with live warheads from a RAF station near Basrah in present-day Iraq. These flights became the first of the numerous cruise missiles to traverse this terrain in the decades to come.

Target drones were introduced in the 1930s in both the U.S. and in Britain as a spin-off of these early cruise missile efforts.


Much more here:

http://www.uavforum.com/library/defnews.doc

In WW-2 the US deployed bomb carrying drones in the Pacific with some success:

http://www.stagone.org/

IIRC the radio control gear used on the Queen Bee was actually based on GPO technology, from their automatic telephone exchanges. The controler had a telephone dial with each number replaced by a command; dive, climb, left turn, right turn etc. The rear cockpit of the Tiger Moth had a dial (the kit filled the forward cockpit) as did the ground stations, and it was a normal testing procedure for a pilot to fly a sortie from the rear cockpit by dialing the commands and letting the gyros do their thing.

Fitting a bomb was thought of, in fact the idea was raised during WWI, and it had been one of the factors driving the whole program from the RAF point of view. But the cost of an airframe, compared to the limited payload, range and accuracy just didn't work. Some thought was given to an incenduary raider, that was basicly a motorised cluster bomb, but the cities targeted were too distant for the existing DH82a based drone, and anything more sophistocated again lost on a cost benifit analysis.

It's been a long time since I read this and I can'tn remember the title, so I might be a bit off on detail, but I'm pretty confident about the overall picture.

shane

Joe, perhaps the statistics about the 0.50 cal AA ammo expendure vs downed targets was mainly based on Tunisy campaign, where it was said that around 100 enemies were shot down by light AA units of US Army ( who knows if there were included the M2 of the AFVs like HT and tanks? I think only quad amount!)

Not that RN AAA direction was any good (until they just adopted the US Mk 37 and fitted it with Brit radar), but to be fair the director systems couldn't "dumb down" enough to cope with an 85 mph airplane. Not even the Stringbag was that slow.

In the same general frame, I have seen it said that the reason Bismarck couldn't hit the attacking Swordfish was that their directors couldn't cope with a plane that slow. I have no idea how they would know this.

Effective at what? Causing damage? Hitting? The two aren't mutually inclusive.

In reviewing the .50s versus the Soviet Mig armament, the USAF determined that the cannon caused more damage when it hit. That's in line with your statement above. But there is a caveat.

They found that the use of the .50s meant there was less arc. Easier for the gunsite in the F-86 to compute. So the .50s were more effective at hitting. Until the velocity is raised on cannon in which case the cannon become superior. I gathered that the Soviet cannon were kind of arcy. Slow firing too. At a leasurely 600rpm the M2, x 6, is giving 3600rpm.


Yes well that whole arc thing and speed thing still applies. US aircraft are still using 20mm. Seems to work.


So I don't think the European move to 30mm is "correct" as much as it just satisfies their desire for a different effect.

Yes, cannon are better. But they have to fire fast and flat in US usage.

To get back to the thread. It wasn't a question of 40mm versus .50. US AAA was in three tiers. At range the 90mm was supposed to do the work. As the aircraft got closer the 40mm kicked in instead of the 90mm. When they were real close the .50s took over. Something to do with the 40mm not being effective up close for some reason. Could be speed of traverse. I could look it up but it takes time.

US Army Active AAA Bns:

31 Dec 42-391
30 Jun 43-547
31 Dec 43-557
30 Jun 44-479
31 Dec 44-347
31 Mar 45-331

Causing damage, certainly - but that includes both hitting and destructiveness. In fact, the ballistics of the 20mm Hispano and the .50 were close enough for this not to be an issue at normal combat distances.

The USAAF was obsessive about velocity in WW2. Yes, it improves hit probability but if you lose a lot of destructiveness then there's not much point. It is interesting that other air forces, with a choice between high-velocity HMGs like the .50 or cannon, invariably chose the cannon as a result of their combat experience.


It isn't really an issue any more, guns have been become so unimportant in air combat..

TW

Surely some of the 20mm cannon had velocities not unlike a 0.50 Browning? The Hispano used on RAF fighters fired a fairly high velocity round IIRC.

You do realize that is why the F-4 was designed without one right?

For hitting, a short time of flight and a high rate of fire are key. The Hispano had good velocity but IIRC the M3 .50 kept a substantial rate of fire advantage.

As for hitting power, two comments:

1. The US had issues with the .50 even in WWII and bungled a .60 development program that would have yielded something like the MG151/15 so even within the "Heavy Machine Gun" philosophy, there was recognition that the .50 was out of steam by 1945.

2. It's purely speculative, but I believe the US was the only air force that never faced a bombing offensive [the arguable exception being Japanese Betties, which may have been the most flammable combat aircraft in WWII] and that this goes a long way towards explaining why they stuck with the .50
USAAF night fighters, which were designed to engage bombers from the start, carried 20mm armament.

Until the guy you're trying to shoot down with a missle has as good or better stealth technology than do you. You might be wishing you had a cannon or two after watching your missles fly harmlessly by the guy who's now shooting his cannons at you.

Planes don't carry a lot of missiles. What do you do if you run out in a furball? Opening the canopy and tossing your thermos at somebody is considered bad form. I suppose you could bomb them with your centerline if you hadn't ejected it before the fight.

The last real fighter on fighter of any real amounts that the US had was VN. I think it was 75% of kills were hitting the other guy with chunks of metal.

Missiles, fire control, sensors and command and control have come a long way since 1972. You've pretty much mastered the art of shooting down enemy fighters before they get within gun range. Gun kills have been exceptional for a long time. How many of the 80 or so kills the Israelis inflict on the Syrians in 1982 were gun? How many air to air gun kills (against fixed wing aircraft) did the US make in 1991?

Lack of thermos and cannon perhaps?

IIRC EF-111s weren't equipped with missiles either.

Yes, but the Luftwaffe switched from their high-velocity 15mm MG 151 to the lower-velocity 20mm version because it was more destructive. And the Russians preferred the 20mm ShVAK over the 12.7mm UB despite the fact that it was heavier, slower-firing and had a lower velocity.

And in both cases, the need to deal with heavy bombers was not an issue: the Luftwaffe's 15 to 20mm switch took place in 1941.

Tony Williams: Military gun and ammunition website and discussion forum