Fw 190 performance

[tomo pauk]

Some things that were applicable to Spitfires before the 2-stage engine is available:
- introduce a better carburetor (presure injection, or the 'fuel pump'); gain was 8-10 mph and 1500 ft of service ceiling vs. the float-type carb
- introduce the less draggy exhaust stacks, like the ones that were observable of Bf 109s of 1938/39 vintage (~7 mph speed gain)
- greater care wrt. fit and finish (loss due to the lousy fit & finish was up to 9.5 mph per RAE tech paper 1273)
- internal BP glass vs. external

With all of this, Spitfire Vs would've been making 380+ mph in a reliable fashion, instead of under 360 mph for series.

 

[planespotting]

Apologies for a rather slow reply - I got pleasantly distracted by the wildly tangential question of whether the Sherman's rather retro anti-tank ammo was based on a French naval round designed in 1910 for indirect fire against thin-hulled torpedo boats...

Against Spitfire V and lesser Allied fighters - better performance, usually better armament, usually better rate of roll.
Against Spitfire IX, XII, P-38H and 'lower, F4U, Typhoon - comparable overall performance, but usually better rate of roll.
Against P-47, Merlin Mustangs, Spitfire XIV, Tempest, late P-38s - worse overall performance, better performance vs. P-47 under 15000 ft, Fw 190 should still roll better.

This is for contemporary Fw 190A version.

This "better performance" is based on... what, apart from rear-area trials?

We should probably start with the Fw 190A-1? It was lighter and less draggy than the A-3, while also available much earlier. See here for the A-1 making 390 mph max on 30 min power rating, and 410 on 3 min power rating (on 25000 ft making ~380 mph on 30 min power) - these are the worst lines on the two graphs.
See here for about 10 km/h worse results for the Fw 190A (which one?) with BMW 801C; the speed graph for the 3-min power (Startleistung, or 'Startl' in that graph) is barely visible, but still.

I've been unable to take German trials metrics seriously since someone pointed out that Bismarck was running her measured mile at 29ft draught...

But this is interesting.

I hadn't really thought of the A-1as a real "production" aircraft - it's got the armament of a Blackburn Skua, the fuselage is streamlined at the expense of proper cooling for the engine, and few if any were ever let anywhere near a Spitfire; but it stands to reason that performance would be improved by enhanced aerodynamics and reduced weight (my unreliable mathematics tell me that omitting the autocannon gives a weight saving of roughly 150kg, or around 5% of airframe weight, all in the wings); so maybe it really was that good - but if so, it wasn't necessarily a useful combat aircraft...

However, given that the BMW 801D's theoretical engine limits weren't practical for squadron service until around 1943 (and even then, how realistically?) I wonder if the A-2 is being measured at an unrealistic performance level...

I don't know. I'm just thinking out loud...

Time to height metrics has everything to do with sustained climb.
With both aircraft fast cruising at, say, 20000 ft at 90% of max speed, the Fw 190 should be doing better in zoom climb category, since it's 90% is higher in true mph that that of Spitfire.

Which Fw 190 do you mean, though? A squadron-service fighter-variant Fw 190 of 1941-1942?

Seems like they achieved a lot.
You can compare the speed figures for the Typhoon, Spitfire XII and the best figures for the Spitfire V. Airforces of the world were usually keen to have faster fighters than what they had yesterday, at least before guided missile became a thing.

Oh, there's always a desire for faster fighters, a belief that pushing the envelope will give improvements - doesn't mean the deicisions made are right or necessary, though...

I've already defined the higher performing - Fw 190, Bf 109F-4.

Well, that at least tells me what you think. I'm busy disagreeing.

Yes.

Why, exactly?

Pictures of a Sherman tank: link

I guess anyone is free to believe what they want, including that M3 halftrack w/ 75mm is better than the Sherman.

Same gun in a more wieldy and much better-ventilated mounting on a chassis with a lower silhouette, higher speed, better range and superior ground pressure... the Sherman's only obvious advantage is its armour, and if you're using lobbed HE properly you don't come in range of direct-fire opposition...

The notional power of 1700hp was in low gear at low altitude, Once you shifted into high gear (at around 8,000ft?) you had a peak of 1440hp at 18,700ft ( 2700rpm/1.42 ata)
It took around 200hp more power to drive the supercharger. You also had the supercharger heating the air more so even though it was at the same pressure it was of lower density.

I just about understand all that! But the practical squadron-service limitation of the 1941-1942 engine wasn't just restricted to the headline power; both boost and rpm are reduced as well...

Since the Merlin 45 was a single speed supercharger and peaked at around 18,000 ft (?)with no ram (3000rpm/ 9lbs of boost) and it NEVER got higher at higher altitudes (20,800ft with 375mph worth of boost) it's high altitude performance never changed. Higher boost at low altitudes was simply opening up the throttle at lower altitudes. It could 15lbs of boost to a lower height than it could using 12lbs of boost. Engines operating any of the higher levels were all going to be using 9lbs of boost at 20-21,000 depending on the actual speed of the aircraft. When turning or climbing the FTH dropped as you don't get as much RAM.

I thought the Spitfire got its boost by flicking a switch...?

*checks* Okay, it seems that the Spitfire has, in Fw 190 terms, "1.41" automatic boost on the throttle, which can be increased by flicking the switch to about "1.8" or, on later aircraft "2.1"...

I'm not sure how that changes what I was saying though?

Depending on the plane other things change. The clipped wing Spits were about 5mph faster at low altitude. about equal at 20,000ft and the full span planes were very slightly faster at high altitudes. The short span wings had less drag at low altitudes but at higher altitudes they had to fly the plane with a slightly greater angle of attack on the wing to make up for the lower amount of lift at the same speed which resulted in more drag. Spitfire wing is sort of case study in changes of wing aspect ratio rather than the change in wing loading. Both were going on. Now the problem is maneuvering rather than flying in a straight line and here the lower lift wings really begin to suffer. If you are trying to pull a 2 G turn the higher drag wing is going to slow you just a bit more than flying straight and level.

Is there any important circumstance where that would cancel out the clear basic advantage in the turn that Spit is said to have retained over the Fw 190 even with the squared-off wing?

Most of the early Jabo's just dropped the MG/FFM cannon in the wings and kept the cowl machine guns.
I am not sure if the 190Fs kept the cowl guns or not. I believe it was not until the 190Gs that the FW was down to just the wing root 20mm guns.

Interesting - the sources I was reading seemed confident that they were using that configuratuion from a rather earlier date...

And in photographs of the Jabo tested at the RAE in '43, you can see it only has the inner pair of wing guns, so yes, it was a lightweight machine with a reduced armament (and a slightly more streamlined airframe too)...

AS far as tanks go
"The Sherman was a tracked SPG designed to fire Schneider 75 HE rounds... a competent vehicle,"
The Sherman tank gun used the same size cartridge case as the Schneider 75 but they used a slightly longer barrel and a slightly heavier powder charge.

None of that changes the fact that they're still firing the same old high-explosive rounds dating from the 1890s; the slightly lengthened barrel and increased powder-charge are designed to compensate for the reduced elevation of the turret mounting, and retain the same range...

The early T-34 tanks used two different length 76.2mm guns and neither offered anything more than 75mm Shermans, except a much lower rate of fire.

Details do matter.

The Sherman lacks a lot of "details" that one would look for in a proper piece of close-combat armour, like a low silhouete, proper anti-tank ammo, a direct-fire gunsight, modern suspension, a sensible chassis weight to maximise ground-pressure and power, a diesel engine as standard; it might also have benefitted from a higher barrel-elevation for increasing the range of the one thing it does usefully, which is lob HE rounds...

-Brutal armament
-Incredible roll rate (amazing ailerons and wing torsional stiffness)

I'd like to be able to distinguish more confidently between the speed/roll numbers that pertain to the fully-armed four-cannon fighter and the numbers that relate to the lightweight variants, though...

The engine was not up to it at high altitudes so luckily for Britain the 190 was beatable.

That was the impression that I had...

If it had been introduced with a 2-stage supercharger, and without the materials shortages which robbed it of
use of full boost for most of its early career, the RAF would have had a very awful time.

How much were the performance limits really "fixable"? I've seen all kinds of excuses quoted... if the answer's simply that I need to read your book, that's fair enough...

Here are comments on the initial use of the Typhoon against low flying FW 190s, from 'Against the Sun, The Story of Wing Commander Roland Beamont, DSO, OBE, DFC.' by Edward Lanchbery:

And that's the sort of thing that shapes the perception I'd picked up, that equates the Fw 190 problem entirely with the low-level tip-and-run Jabos...

The questions that arise are, of course, whether that perception is the whole story, whether the the advantage gained by the Tiffy was unique, and whether the Griffon Spit was really as outclassed as that narrative makes it out...

You don't have to answer, I'm just glad to confirm that there was a little more depth to the ideas I'd picked up...

It should also be mentioned that the FW 190 did not only face fighters, despite their low flying and short time over the target area they still lost aircraft, for example on 30th May 1943 SKG10 did not have a good day:

No, they did not!! But equally, that's very clear evidence them continuing daylight tip-and-run against small resort towns in mid-1943, after the official shift to night-bombing London, just days before they were sent to Italy... that's the sort of information that I was looking for - thank you!!

(And that's the first part of an overlong two-part response!)

 

[planespotting]

(Part Two!!)

This forum cannot possibly fulfill those requirements, reading several books on the subject is required.

Several more books on the subject, ones with a deeper focus... which I don't know where to find... and which I'm honestly surprised people haven't been throwing at me...

I presume you mean the Baby Blitz which started in January 1944 and the reason the Mosquitoes could intercept was the Fw190 were cruising as they had to fly further to London at a higher altitude than the ports raids needed. The defences were inflicting losses on the day Jabos, but the very nature of the raids meant they could not be stopped short of large numbers of standing patrols, or better early warning.

No, I mean the earlier switch to night-bombing of London in April 1943, which I admittedly didn't know about until this discussion...

And I'd need to figure out exactly where the Jabos were staging from, but London is actually rather closer to the continent than a lot of the holiday towns that were the tip-and-run targets, because of the narrowness of the straits of Dover...

No, you are comparing flight test performances of new aircraft with tests of squadron aircraft and assuming the allies did push the Fw190 under test to its limits. The book Spitfire by Morgan and Shacklady has a number of test results, for example Spitfire Vc AA878 which had top speeds with various armament fits of between 353 and 359.5 mph at 19,000 feet. Compare results done under similar circumstances. Similarly do not assume a Jabo version has fewer guns and ask about bomb racks fitted. Do not forget Spitfires were using external fuel tanks with associated racks. That the mark V came with a variety of engines and propellers, fitting a snow or stone guard clipped around 8 mph from the speed at 360 mph. Your perceptions are based on invalid comparisons.

With respect, you're assuming a level of incompetence on my part that's egregious even by my own low standards...

I wasn't "assuming" the Jabo had fewer guns, I was quoting a statement about the lightweight/reduced-armament configuration of the Fw 190A-4/U8 that's widely repeated in literature on the topic - and which turns out to be easy to confirm for the aircraft as-tested...

And I was quoting the test results done without underwing stores for that plane, just as I was quoting the results without similar add-ons for the Spitfire V...

As to limits, they were running a succession of short, separate climb and speed trials with the engine at full power with its cooling shutters closed, then giving the plane several days of overhaul between them...

So we're looking at a Fw 190A-4 with a clean wings and a light weight, being pushed in ways that couldn't be done as part of a sustained flight...

That doesn't change the fact I'm just a curious amateur with a lot of questions, and there's plenty I know I don't understand...

For example, I was under the impression that the Spitfires the RAE tested were just ordinary squadron aircraft... maybe not, I don't know?

The large number of RAF and Luftwaffe pilot reports indicate the Fw190A had a real performance edge over the Spitfire V, if you are going to contradict them you need to explain why they are incorrect.

I'm not saying they're incorrect, I'm pointing out that, as mediated through the available sources, those perceptions appear to be heavily focused on attempts to intercept tip-and-run Jabos flying at low altitude on the way back out from clearing their underwing stores on Torquay or Clackton; no-one is disputing that the Fw 190 was always excellent below around 5000ft (though I do start to wonder if the fighter variant with twice the weight of cannon in the wings wasn't quite the same roll-rate king)...

Try the Fighter Command War Diaries. 41 squadron received Spitfire XII in February 1943, giving up its Spitfire V in March, 91 squadron had XII arriving in April, last V leaving in May, 595 squadron had Spitfire XII December 1944 to July 1944, along with various other target tow types.

Thanks - war diaries are definitely useful, and I need to look into the RAF ones...

But, as a placeholder on the specific topic, a widely-quoted excerpt from the 41 Squadron war diary refers to the Mk.V still being in service with the wing (i.e. 41 and 91 Squadrons) at the end of September 1943... does that mean that they'd not actually given them all up, or does it mean that they got some more as replacements?

The Sherman was a tank, not an SPG. Is this conclusion based on reliability, maintenance requirements, useable terrain, turret speed or just power of gun and thickness of armour? In 1942/43 the Germans shifted from tank largely avoid tank to tank as anti tank. Meantime they tasked the assault gun as infantry support. The US largely kept the original ideas about tanks, creating the tank destroyers as the anti tank force. The result was the Sherman, more reliable, lower maintenance, able to go more places than German tanks, with the ability to train its gun quickly, useful for the close encounters so often found in Normandy. Shermans kept turning up for the battle much more often than German types did. The closer terrain in the west reduced the average range and made a turret much more useful than the relatively fixed assault gun mounts. Combined arms doctrines meant tanks were mostly attacking with infantry and suppressing the weapons hurting the infantry rather than engaging in fire fights with other tanks. I am reminded about how a group of M18 Hellcats took on some Panthers at close range, ambush followed by full speed driving while shooting as the Panthers could not train their guns quickly enough to shoot back.

The Sherman's bulk and amateurish armour layout (that bizarre glacis with its redundant angles, two shot-trap hatches, and multiplicity of bolt-ons, those high vertical sides) are not what you want in the breakthrough / close-support role, and as we seem to agree, the gun lacks the anti-tank capability you'd look for in a crusier; thus it's really only useful as a mobile platform for ranged HE - hence my characterisation of it as, in fact, an SPG; and while it's reasonably reliable, certainly by comparison with the panzer "big cats", it's firmly outclassed by other SPGs, see my comments on the M3 portee.

The American "TD" types also have a performance advantage over the Sherman, though again, they're a rather overdesigned alternative to an M3 portee, and they don't have the Sherman's one strength - namely comparatively heavier armour and an enclosed fighting compartment...

See above for why the comparisons are misleading, also I am quoting the A-8 as it comes from an Eric Brown book and was the only one I could find with climb to altitude figures.

I did very much appreciate the time-to-height number, but at this particular point, what confused me was that you were quoting a 1944 plane's low-altitude mph in the context of a 1941-1942 plane's high-alititude performance...

And to reiterate a point I conceded earlier - precisely because I was thinking of the Fw 190 in terms of tip-and-run raids, I'd certainly overlooked the late variants that arrived in numbers after the Allied advance on the ground forced the Luftwaffe backwards...

Where does 15,000 feet come from? Or 5,000 feet? I noted 12,000 feet was considered high for the allied tactical air forces. Next comes the obvious point, why are all those allied armed reconnaissance flight assumed to be at those heights? And presumably going back to them after bombing and strafing. Where is the evidence? So far it comes down to a remembered idea about Fw190 fighter bomber losses, which hits the reality of what the Luftwaffe losses actually were followed by attempts to come up with a way of making the two fit. Do not speculate, provide the actual evidence.

15,000ft is the rough celiling for Allied fighters flying masks-off, 5,000ft is the rough ceiling of the Fw 190's superb low-level performance...

I do need to dig up what I remember reading, though - I agree on that!

And, on that topic, well... this short summary in an Osprey book records that III./SG 4 was decimated in the three weeks after D-Day, which shows that some Fw 190 units were being absolutely mauled, but this more detailed narrative shows that a large proportion of the damage was done by attacking ferry flights and ground strafing; and conversely, that same Osprey mentions that I./SKG 10, which I suspect might be the unit I was thinking of, lost only twenty aircraft between June and August 1944. And IV./JG 4, an interceptor unit that was somewhat inexplicably redeployed to Normandy in the low-altitude Jabo role, recorded only two planes lightly damaged in non-combat incidents during their short deployment on 8th-15th June 1944, which given the timeframe seems quite remarkable.

So, while the picture's complicated, yes, there's some indication that Allied successes against Fw 190 Jabos in the air over Normandy was surprisingly limited...

What all this is reminding me of is something I read about, of all things, the Westland Lysander with the BEF... where it seems to have had a surprisingly rugged survivability in the ground-attack role, but aircraft abandoned on the ground were counted in the overarching campaign reports as if they'd been shot down...

And I'm honestly not sure what altitude Allied fighter sweeps were, or whether Allied attack missions used diving attacks - I agree that needs to be checked too!!

Until the Fw190A-6 of mid 1943 there were 3 different types of guns on board with different ballistics and velocities. Removing the outboard cannon in the A-5 and earlier was a common modification. The Bf109G-6 came along around March 1943, with the firepower upgrade to heavy machine guns and could be fitted with a 30mm cannon. Things like the Fw190 being easier to land and having a better view are reasons for liking it.

Makes sense to me - deconstructs the supposed correlation between pilot enthusiasm and speed performance a little more, though...

For general interest, these drafts are notable in the fact that the author appears to have gone to considerable length to redraft them and edit them to a degree
which is not usual even for drafts, which are common in these files.

I would attribute this to his trying very hard to make things look a bit more rosy. each draft is a little less panicked.

The thing that jumps out at me from these glimpses is that he's trying to say that the tactics have been a success and blaming the associated losses on the Fw 190; is this narrative a cover to excuse a change in tactics? If so, the idea that the tactics would work fine with a faster plane might not be what they wanted to communicate (Churchill's response would probably be to immediately assign Mosquito NFs for rhubaring and responding to tip-and-run, which might have been interesting)...

I've also not yet seen any specific evidence that the Fw 190 was really causing significant problems in the fighter role as opposed to the Jabo role...

For example, the Osprey-level book on JG2 provides an extensive overview of their activities on the Channel in 1941-1943 (pp. 72-95) that only mentions significant conventional fighter activity before they converted to the Fw 190 in 1942; after that, the focus seems to be on interecepting B-17s and occasional tip-and-run raids...

Next trick is to go through the JG26 records and try and distinguish the Fw 190 fighters from the Bf 109 and tip-and-run units... if there's a basis to the idea that the Fw 190 was doing well at altitude in 1941-1942, it would presumably be in their activities, though it's possible that the distinctive arrival of the Fw 190 in the mix led to it getting credit from the RAF for achievenments of the less visibly "new" Bf 109F...

Some things that were applicable to Spitfires before the 2-stage engine is available:
- introduce a better carburetor (presure injection, or the 'fuel pump'); gain was 8-10 mph and 1500 ft of service ceiling vs. the float-type carb
- introduce the less draggy exhaust stacks, like the ones that were observable of Bf 109s of 1938/39 vintage (~7 mph speed gain)
- greater care wrt. fit and finish (loss due to the lousy fit & finish was up to 9.5 mph per RAE tech paper 1273)
- internal BP glass vs. external

With all of this, Spitfire Vs would've been making 380+ mph in a reliable fashion, instead of under 360 mph for series.

Are there that many examples of the Mk.V that are limited to "under 360 mph"? Most figures I've come across for the Mk.V with a Merlin 45 are in the 370-375mph range...

You're not wrong about the individual details; I just don't really know anything that says they made that much difference...

 

[Shortround6]

I thought the Spitfire got its boost by flicking a switch...?

flicking the switch just changed the boost allowed by the boost limiting device attached to the supercharger (ie, the throttle)
If your supercharger gives you 9lbs of boost at 20,000ft (hypothetical) that is most it can give at 20,000ft with the throttle fully open. and it will give progressively less as you go higher into thinner air. As you go lower the boost limiting device closes the throttle to limit the amount of air going into the supercharger and limits the power to keep the pilot from wrecking the engine in normal flight. In an emergency, like with bullets going past the windscreen, the pilot could hit the switch/button and move to higher preset boost. BUT since the supercharger itself can only multiply the pressure of the outside air by a fixed amount the ultimate limit is the product of the ambient air pressure times the pressure ratio of the supercharger. This upper pressure limit was changed several times with experience as to how much power the engine could make and not break (mostly) and as a few small weak points were fixed on later engines or when refitted. If you are above the full throttle height you can flick the switch or pound on the button all you want, you don't get any more boost/power.

wildly tangential question of whether the Sherman's rather retro anti-tank ammo was based on a French naval round designed in 1910 for indirect fire against thin-hulled torpedo boats...

I don't know where you are getting your information from but they have same serious drugs.
The French 75 dates 1897.
It was an army gun. The Navy got some in WW I for small ships when there was a gun shortage.
Thin hulled pre war WW I torpedo boats didn't need Armor piercing ammo to deal with.
Indirect fire works like crap against fast moving targets like a torpedo boat. You want the flattest trajectory possible for the shortest time of flight.

Same gun in a more wieldy and much better-ventilated mounting on a chassis with a lower silhouette, higher speed, better range and superior ground pressure... the Sherman's only obvious advantage is its armour, and if you're using lobbed HE properly you don't come in range of direct-fire opposition...

see below

None of that changes the fact that they're still firing the same old high-explosive rounds dating from the 1890s; the slightly lengthened barrel and increased powder-charge are designed to compensate for the reduced elevation of the turret mounting, and retain the same range...

The 1897 gun and all of the WW I copies had about 16 degrees of elevation due to the pole carriage. The Sherman actually had better range than the old field guns had.
The primary round in WW I was the shrapnel round, Shell had a small burster and was full of small balls/bullets that were blown out of the front of the shell by the buster (which also marked the point of detonation to the gunners) over the heads of the enemy troops. Think of it as long range cannister. It was pretty much useless without an observer who could communicate not only range and bearing to the target but where the shells were detonating in regards to troops. HE ammo was very much a secondary item until 1914/15 and by then it was too late, the French were stuck with 75 and resorted to digging in the trail to get more elevation and resorting to clipping discs/washers behind the fuse to get the shells to fall more steeply at shorter ranges.
The US had put the old barrels on new carriages with more traverse and more elevation. However fixed charge guns had a lot of trouble with indirect fire. The US used very few of the towed 75mm guns in combat.
Where ever you are getting your information from doesn't know the history of the French 75, it's ammunition types and usage. Yes it changed over 40 years but then there is no reason to bring up the old stuff.

The Sherman lacks a lot of "details" that one would look for in a proper piece of close-combat armour, like a low silhouete, proper anti-tank ammo, a direct-fire gunsight, modern suspension, a sensible chassis weight to maximise ground-pressure and power, a diesel engine as standard; it might also have benefitted from a higher barrel-elevation for increasing the range of the one thing it does usefully, which is lob HE rounds...

so much wrong here.
Proper anti-tank ammo?????
They had both plain AP shot and capped Ballistic capped AP shot and would shoot any German tank from the front up to about 2000yds until the Tiger showed up.
The M4 had a direct vision gunsight.
It had a decent suspension.
It had a decent power, or at least better than the German tanks. It also had a decent transmission. If you are comparing it to a T-34 you have to look at them as a unit. Soviets needed more power because they had trouble shifting gears and they needed more power to actually maneuver the tank cross country in less than the ideal gear because they couldn't shift it.
tanks are supposed to be direct fire weapons. If you want indirect fire you call for the 105 howitzers which can delivery HE much more efficiently than 75mm guns which is why many armies stopped using 75mm field artillery in WW II.

Getting information from you tube videos or German or Soviet Fan boy websites is going to lead you in the wrong directions.

 

[ThomasP]

All early production M4/M4A1/M4A2/M4A4 had an M4 periscope type gun sight with a 1x indirect telescope M38, or the M4A1 periscope sight with a 1.44x indirect telescope M38A2, for the 75mm gun. The Sherman did not begin to be fitted with a direct 3x telescope sight until early-1943. Basically, any Sherman with the M34 style of gun mount shown in the image below had the periscope sight only:

You can see there is no opening for a direct vision telescope in the mount or gun shield.

The M34A1 mount (shown below) with direct 3x telescope sight was fitted on the production line beginning in early-1943. In many cases the periscope sight was retained. The M34A1 gun mount was also retrofitted to most surviving early production Shermans as time allowed.

You can see the opening for the telescope sight in the right side of the widened gun shield, as well as the periscope sight on the top of the turret.

An improved M10 periscope sight with a dual 1x/6x indirect telescope incorporated was developed for use in some of the later-war 75mm gun variants.

Very late-war and post-war Sherman turret variants did away with the periscope sight.

 

[tomo pauk]

This "better performance" is based on... what, apart from rear-area trials?

It is based on ~40 years of reading and listening about the ww2 aircraft, both in vernacular as well as in foreign languages - English, German, Russian (sprinkled a bit with French and Italian books and magazines).

I hadn't really thought of the A-1as a real "production" aircraft - it's got the armament of a Blackburn Skua,

However, given that the BMW 801D's theoretical engine limits weren't practical for squadron service until around 1943 (and even then, how realistically?) I wonder if the A-2 is being measured at an unrealistic performance level...

I don't know. I'm just thinking out loud...

If you really think that A-1 have had only 4 forward-firing LMGs as armament, as well as that 801D has anything to do with A-2, perhaps some further reading on the Fw 190 is in order.

Which Fw 190 do you mean, though? A squadron-service fighter-variant Fw 190 of 1941-1942?

Yes.

Oh, there's always a desire for faster fighters, a belief that pushing the envelope will give improvements - doesn't mean the deicisions made are right or necessary, though...

They were necessary for Spitfire, and later they were necessary for Fw 190.

Well, that at least tells me what you think. I'm busy disagreeing.

You certainly are.

Why, exactly?

Feel free to do some homework.

Same gun in a more wieldy and much better-ventilated mounting on a chassis with a lower silhouette, higher speed, better range and superior ground pressure... the Sherman's only obvious advantage is its armour, and if you're using lobbed HE properly you don't come in range of direct-fire opposition...

Not gonna discuss Sherman with you here anymore.

Are there that many examples of the Mk.V that are limited to "under 360 mph"? Most figures I've come across for the Mk.V with a Merlin 45 are in the 370-375mph range...

You're not wrong about the individual details; I just don't really know anything that says they made that much difference...

Haven't I supplied the link of the site with big numbers of tests and performance encounters days ago? Alas.
See here, for a good measure: link (scroll to the bottom table)

 

[Geoffrey Sinclair]

I've been unable to take German trials metrics seriously since someone pointed out that Bismarck was running her measured mile at 29ft draught...

Good, we will all now stop presenting the German aircraft performance data, since a ship performance data was done, according to you, at an inappropriate loading condition, so the aircraft data is uspect. By the way, just to be sure you know, the USN allowed seawater into ship fuel tanks as the oil was burnt, keeping the ship at roughly the same displacement and thereby enabling heavier armament (top weight), the RN did not, hence quotes of RN destroyers as top speed 32 knots full load, 36 knots light load. Given how many references quote the RN destroyers as 36 knot ships, I have just invalidated allied aircraft test performance results, if I want to.

Compare like with like, the initial proof of maximum performance trials with new aircraft, test pilots etc. or the results from aircraft after or during squadron service, the latter will normally be less. Similarly a warship will be progressively slowed down the longer it goes without a hull clean.

On the Sherman versus the 75mm on a half track.

Same gun in a more wieldy and much better-ventilated mounting on a chassis with a lower silhouette, higher speed, better range and superior ground pressure... the Sherman's only obvious advantage is its armour, and if you're using lobbed HE properly you don't come in range of direct-fire opposition...

A main advantage to tanks is they are bullet proof, good to hide behind as you advance, good to avoid exposing the gunners to enemy small arms fire, and the turret can be trained, instead of the half track needing to be pointed at the target. Finally it is notable the idea is the allied system would work so well that the troops could advance without vehicle support and call in effective artillery fire kept out of German sight comparable to having tank support and the Germans would be obliging in terms of allowing targets to be located. A major attribute of a good break through tank is reliability, able to go further into the enemy rear, the Red Army liked the Sherman for that.

Several more books on the subject, ones with a deeper focus... which I don't know where to find... and which I'm honestly surprised people haven't been throwing at me...

Perhaps showing you have looked at Morgan and Shacklady would encourage people.

And I'd need to figure out exactly where the Jabos were staging from, but London is actually rather closer to the continent than a lot of the holiday towns that were the tip-and-run targets, because of the narrowness of the straits of Dover...

Ignoring the obvious problems with distances, flying to London means over land areas that have raid observer systems in place, unlike the salt water areas around Britain. Now please define rather closer and a lot of. Target list and distances.

And I was quoting the test results done without underwing stores for that plane, just as I was quoting the results without similar add-ons for the Spitfire V...

Racks removed?

For example, I was under the impression that the Spitfires the RAE tested were just ordinary squadron aircraft... maybe not, I don't know?

When a new type emerges the prototype/initial production is sent off to be tested and these become the official performance data, test establishments did a lot of other testing, including reported rogue aircraft for example.

I'm not saying they're incorrect, I'm pointing out that, as mediated through the available sources, those perceptions appear to be heavily focused on attempts to intercept tip-and-run Jabos flying at low altitude

No, your focus is on the fighter bombers, a minority of the Fw190 sorties in the west in 1941/43, everyone else is on the air combat results, which show the Fw190 had a decisive performance edge over most of what it faced into early 1943.

But, as a placeholder on the specific topic, a widely-quoted excerpt from the 41 Squadron war diary refers to the Mk.V still being in service with the wing (i.e. 41 and 91 Squadrons) at the end of September 1943... does that mean that they'd not actually given them all up, or does it mean that they got some more as replacements?

The squadron diaries are online at the British National Archives.

The Sherman's bulk and amateurish armour layout (that bizarre glacis with its redundant angles, two shot-trap hatches, and multiplicity of bolt-ons, those high vertical sides) are not what you want in the breakthrough / close-support role

A fine example of reputational destruction by adjective. The sloped front plate, the fast turret tracking, the range of useable terrain, the effective HE round.

it's firmly outclassed by other SPGs, see my comments on the M3 portee.

I assume those were for humour.

15,000ft is the rough celiling for Allied fighters flying masks-off, 5,000ft is the rough ceiling of the Fw 190's superb low-level performance...

The altitudes were retrofitted as reasons for a given outcome, please do dig up the information before replying again.

So, while the picture's complicated, yes, there's some indication that Allied successes against Fw 190 Jabos in the air over Normandy was surprisingly limited...

Complications like for example how many sorties did the various units undertake? The allied interdiction campaign meant the Luftwaffe airfields rapidly had fuel, ammunition and spare parts supply problems, or even started with them, also bombed airfields tend to have reduced operations even if supplies are available. What remained of the Luftwaffe fighter force was down to 50% serviceability at the end of June. Easy to avoid combat losses if there are few combat sorties. A given unit will have runs of few or heavy casualties, the "Bloody Hundredth" comes to mind in the USAAF, 5 Luftwaffe fighter gruppen had to be withdrawn by June 11 due to losses.

What all this is reminding me of is something I read about, of all things, the Westland Lysander with the BEF... where it seems to have had a surprisingly rugged survivability in the ground-attack role, but aircraft abandoned on the ground were counted in the overarching campaign reports as if they'd been shot down...

How many ground attack sorties did the Lysander do in France in 1940? How many sorties in total? They were short range reconnaissance units, how much of the Luftwaffe effort was intercepting these? A large percentage of RAF losses in France were abandoned aircraft. As soon as possible the RAF phased the Lysander out, replacing it with P-40 and P-51 in Britain and other fighters in the Middle East.

I've also not yet seen any specific evidence that the Fw 190 was really causing significant problems in the fighter role as opposed to the Jabo role...

In the fighter role 1941 to 1943 the Fw190 was shooting down allied aircraft at a much higher rate than allied aircraft were shooting down Fw190. In the fighter bomber role the Fw190 was hitting coastal targets and even then taking overall losses that were long term unsustainable, but shooting down few allied aircraft. No wonder you have not seen any specific evidence given the logic of the comparison. And since the Bismarck rule exists you are unlikely to ever see such evidence.

. if there's a basis to the idea that the Fw 190 was doing well at altitude in 1941-1942, it would presumably be in their activities, though it's possible that the distinctive arrival of the Fw 190 in the mix led to it getting credit from the RAF for achievenments of the less visibly "new" Bf 109F...

This comes across as conclusion written, evidence now sought to back it up. While there were plenty of misidentifications the Fw190 had a lot of obvious differences to the Bf109.

By the way the US armies in France had about 37% light tanks in 1945. Notes from a discussion on the Sherman, mostly by other people. Being in production for so long there were lots of changes, the protection and combat power related improvements in early 1944:

The 47 degree sloped front plate, there was an increase in thickness (2 to 2.5 inches) plus the elimination of shot traps and the extra slope to improve protection. Thicker glacis. Wet Stowage (but not for the 105mm or Jumbo versions). The 76mm gun, the 75mm versions with the protection improvements comprised around 40% of production January to May 1944, and 100% thereafter. All 76mm versions had the improvements. Also better optics. During the production run there was quite a bit else that happened. In the M4A1 casting quality was notably better, improving protection, the M4A3 glacis was probably at least a 50 percent improvement over the previous, ammunition stowage was better, and so on. Despite the lack of wet stowage and use as direct infantry support the 105mm Shermans of 12th Army Group had about a third the loss rate of the other Sherman types in 1945. Different usages were seen between 1st and 3rd Armies, from 20 July 1944 onwards the former loss percentage rate was about three 75mm to two 76mm, the latter one 75mm to two 76mm, with 9th Army was closer to 1 to 1.

Early production M4 with 75mm were manufactured with the M38 Telescope with M4 Periscope, then went to the M55 Direct Telescope and the M38/M4, and finally the M70F Direct Telescope and the M38A2/M4A1 Periscope (M4A3). The M4A3E2 was manufactured with the M71G Direct Telescope and M38A2/M4A1 Periscope. M4 76mm were manufactured with the M71D Direct Telescope and M47A2/M4A1 Periscope.

The M71-series was designed for the 76mm, except the "G" which was a one-off modification designed for the 75mm in the M4A3E2 since that tank utilized a modified version of the 76mm gun mount and shield. The M70-series was for the 75mm, again except the "G" which was utilized in the M10. The ultimate 76mm sight during the war was the M71F and for the 75mm it was the similar M70F. The M71F didn't become available until Q3/44 in the current production and in limited quantities for retrofitting to existing vehicles.

The M10 was manufactured with the M70G, the M18 with the M71D, but probably also utilized the M71F. The M36 utilized the M76D. It should be noted the tank destroyers received better optics earlier than the Shermans did and that some older vehicles were modified to take the better optics. The actual differences between the later types for the 75mm, 76mm, and 90mm were all incremental improvements, the basic design of the telescopes were similar, but with different reticules for the different gun characteristics.

The original periscopic sights were pretty decent, but the complicated linkage made them difficult to keep aligned with the gun and contributed to inaccuracy. And the original direct telescopes were awful, poor field of view, single power IIRC, and it was almost impossible to see the graticules in anything approaching less than perfect lighting conditions. The second generation optics were much better, especially the direct telescope, which had a better field of view than the German, two magnification settings, and much improved light characteristics. Comments in the field were that they were just about - but not quite - as good as the German.

For the period 20 September 1944 to 20 February 1945 in 12th Army Group the tank loss figures indicate for every 1% of M36 strength lost, 1.8% of M18 and 2.7% of M10 strength was lost. Almost, but not quite 1 to 2 to 3. While the numbers here are a guide, and certainly overestimate the M10 vulnerability, it is reasonable to assume that in fact the extra speed did keep M18 losses below M10 losses, and the 90mm gun on the M36 enabled an even lower loss figure.

 

[EwenS]

planespotting

For all things Sherman you need to spend some serious time on the Sherman Minutia website. Its evolution between the 1942 prototype and the late 1944/45 production variants is remarkable. All the versions, engines, guns, suspension, turret, individual factory features, production data, etc, etc can be found there.

Sherman minutia homepage

The following books are also worth acquiring

Sherman: A History of the American Medium Tank: Amazon.co.uk: Hunnicutt, R.P.: 9781626548619: Books

Buy Sherman: A History of the American Medium Tank Reprint ed. by Hunnicutt, R.P. (ISBN: 9781626548619) from Amazon's Book Store. Everyday low prices and free delivery on eligible orders.

www.amazon.co.uk

Armored Thunderbolt: The U.S. Army Sherman in World War II eBook : Zaloga, Steven: Amazon.co.uk: Books

Armored Thunderbolt: The U.S. Army Sherman in World War II eBook : Zaloga, Steven: Amazon.co.uk: Books

www.amazon.co.uk

US Tank Destroyer history and development is a wholly different line of study.

https://www.armyupress.army.mil/Portals/7/combat-studies-institute/csi-books/gabel2.pdf

 

[PAT303]

With all of this, Spitfire Vs would've been making 380+ mph in a reliable fashion, instead of under 360 mph for series.

Spitfire Mk VA X.4922 Report

The trouble with the Spitfire is you have a plethora of engines, props, guns, exhausts, snow shields, gun blisters, gun shrouds, barrel stubs, boost ratings, RPM ratings, fuel octane numbers and fit and finish, the list goes on. This one did 375mph so very close.

 

[planespotting]

Another overlong multipart reply - and (asking mostly to try and lighten the tone) should I apologise in advance for the long pause, or for replying at all?

flicking the switch just changed the boost allowed by the boost limiting device attached to the supercharger (ie, the throttle)
If your supercharger gives you 9lbs of boost at 20,000ft (hypothetical) that is most it can give at 20,000ft with the throttle fully open. and it will give progressively less as you go higher into thinner air. As you go lower the boost limiting device closes the throttle to limit the amount of air going into the supercharger and limits the power to keep the pilot from wrecking the engine in normal flight. In an emergency, like with bullets going past the windscreen, the pilot could hit the switch/button and move to higher preset boost. BUT since the supercharger itself can only multiply the pressure of the outside air by a fixed amount the ultimate limit is the product of the ambient air pressure times the pressure ratio of the supercharger. This upper pressure limit was changed several times with experience as to how much power the engine could make and not break (mostly) and as a few small weak points were fixed on later engines or when refitted. If you are above the full throttle height you can flick the switch or pound on the button all you want, you don't get any more boost/power.

All informative, and appreciated (I assume that part of what this means is that the notional figure for boost is actually a gross overstatement at higher altitudes, but also that the lower ambient pressure of the surrounding air will reduce its heat-loading properties and the cooling efficiency of the engine); but I'm still not sure if this has some significance in the relative performance of the Spitfire Mk. V and Fw 190 at these altitudes that I'm failing to grasp...

(I get that the Fw 190's two-speed blower, however imperfect the experts say it is, improved its performance at lower altitudes!)

I don't know where you are getting your information from but they have same serious drugs.
The French 75 dates 1897.
It was an army gun. The Navy got some in WW I for small ships when there was a gun shortage.
Thin hulled pre war WW I torpedo boats didn't need Armor piercing ammo to deal with.
Indirect fire works like crap against fast moving targets like a torpedo boat. You want the flattest trajectory possible for the shortest time of flight.

The French navy adopted a Schneider 75mm gun in 1908 as the secondary armament of the Danton-class battleships; as a weapon it didn't have that much commonality with the modèle 1897, but its M1910 ammo could be swapped over, and was adopted, faute de mieux, as an anti-armour round for the mle1897 around 1918...
I suspect that the M1910 ammo isn't actually strictly an AP round, more of an all-rounder that emphasises penetration and fragmentation over blast; so-called "splinter damage" (i.e. frag from near misses detonating on the sea surface) was seen as an important weapon in the original context...
And you need indirect fire for range, as you're expected to engage the torpedo boats at around 8,000 yards with significant elevation on the gun...

Obviously, there's a long road from there, via the Char B1, to the question of influence on the Sherman's M72 AP round, but I don't want the tangent to get too long, so I'll limit the reply to defending the validity of the specific remarks you took exception to...

The 1897 gun and all of the WW I copies had about 16 degrees of elevation due to the pole carriage. The Sherman actually had better range than the old field guns had.

And by the 1930s both the French and US had modified the carriage to improve elevation, which was what the Sherman was designed to match...

The primary round in WW I was the shrapnel round, Shell had a small burster and was full of small balls/bullets that were blown out of the front of the shell by the buster (which also marked the point of detonation to the gunners) over the heads of the enemy troops. Think of it as long range cannister. It was pretty much useless without an observer who could communicate not only range and bearing to the target but where the shells were detonating in regards to troops. HE ammo was very much a secondary item until 1914/15 and by then it was too late, the French were stuck with 75 and resorted to digging in the trail to get more elevation and resorting to clipping discs/washers behind the fuse to get the shells to fall more steeply at shorter ranges.
The US had put the old barrels on new carriages with more traverse and more elevation. However fixed charge guns had a lot of trouble with indirect fire. The US used very few of the towed 75mm guns in combat.
Where ever you are getting your information from doesn't know the history of the French 75, it's ammunition types and usage. Yes it changed over 40 years but then there is no reason to bring up the old stuff.

None of this changes the fact that the HE round dated back to the 1890s, or contradicts anything I was saying...

The only thing you mention there that I didn't know about was the preponderant emphasis on shrapnel ammo for the Schneider circa 1915, but this seems to have been the result of a deliberate switch of production policy in late 1914 and early 1915 by the new directeur de l'Artillerie, General Basquet, narrated in the relevant chapter in his autobiography; HE ammo was not "secondary" to the original design...

But it's amazing what you end up finding out when curiosity about the Blackburn Skua's engine gets the better of you...

And yes, the towed Schneider didn't end up being widely used by the US in '41-'45, but a fairly obvious reason for that was the presence of huge numbers of vehicle mounts, including Shermans, M3 half-track portees, M24 Chafees, M8 tracked SPGs with the M116 mountain gun, and the vast numbers of British tanks with their guns nerfed to fire the same ammo...

so much wrong here.
Proper anti-tank ammo?????
They had both plain AP shot and capped Ballistic capped AP shot and would shoot any German tank from the front up to about 2000yds until the Tiger showed up.

The Sherman's 75mm AP round is a lump of low-grade steel shaped like a late-Victorian HE shell, and fired at the muzzle velocity of a late-Victorian infantry-support gun; the M61 APCBC version ought to improve range/velocity somewhat over the basic M72, but it's still dressing up a primitive shot in fancy clothes; everyone else making AP rounds in the early 1940s went for absolutely fierce muzzle velocity, or more sophistication in design and/or metallurgy...

The M4 had a direct vision gunsight.
It had a decent suspension.
It had a decent power, or at least better than the German tanks. It also had a decent transmission. If you are comparing it to a T-34 you have to look at them as a unit. Soviets needed more power because they had trouble shifting gears and they needed more power to actually maneuver the tank cross country in less than the ideal gear because they couldn't shift it.

See below on the (lack of) gunsight; as to the suspension, small, widely-spaced roadwheels with limited travel are not what I'd expect in a "decent" tracked-armour system of the early 1940s...

And I'm comparing the Sherman to pretty much everything; it's got about the worst ground-pressure of any tracked AFV of the period, reinforced by power-to-weight that's, at best, mediocre (it seems the only types that it really does better than in that regard are the Churchill and Kingtiger, until the Easy Eight shows up in limited numbers in 1945 - applying the Ford V8 of the Jumbo to a normal-weight hull edges it ahead of the Tiger I and the Pz III and Pz IV, and the associated redesign of the running gear definitely improves the ground pressure too)...

tanks are supposed to be direct fire weapons.

Yes, I agree. The Sherman isn't much of one, though...

If you want indirect fire you call for the 105 howitzers which can delivery HE much more efficiently than 75mm guns which is why many armies stopped using 75mm field artillery in WW II.

There's a valid debate here about whether the higher weight-of-shot of something like a 105mm cancels out the better rate-of-fire of a 75mm and the ability to use a lighter and more mobile vehicle underneath it - I don't have a particular opinion on the topic...

Getting information from you tube videos or German or Soviet Fan boy websites is going to lead you in the wrong directions.

I'm not! Why are you assuming I am...?

All early production M4/M4A1/M4A2/M4A4 had an M4 periscope type gun sight with a 1x indirect telescope M38, or the M4A1 periscope sight with a 1.44x indirect telescope M38A2, for the 75mm gun. The Sherman did not begin to be fitted with a direct 3x telescope sight until early-1943. Basically, any Sherman with the M34 style of gun mount shown in the image below had the periscope sight only:

View attachment 720259

You can see there is no opening for a direct vision telescope in the mount or gun shield.

The M34A1 mount (shown below) with direct 3x telescope sight was fitted on the production line beginning in early-1943. In many cases the periscope sight was retained. The M34A1 gun mount was also retrofitted to most surviving early production Shermans as time allowed.

View attachment 720224

You can see the opening for the telescope sight in the right side of the widened gun shield, as well as the periscope sight on the top of the turret.

An improved M10 periscope sight with a dual 1x/6x indirect telescope incorporated was developed for use in some of the later-war 75mm gun variants.

Very late-war and post-war Sherman turret variants did away with the periscope sight.

Yep! But that doesn't change what I'm saying...

The turret-top periscope is primarily an observation device rather than a real gunsight - the sighting component is a ranging reticle, graded to allowed the gunner to estimate the distance to a target and thus elevate the gun to throw explosive rounds to ranges out to around 3000yds; the periscope's position diagonally off-axis from the gun and its basic lack of linear precision means it's not really useful for aiming of the sort needed to hit a target in the direct-fire anti-armour role...

The M55 telescope, which entered production in March-April 1943, was an attempt to provide the Sherman with something resembling a proper gunsight, mounted coaxially with the gun; but it was still only really graded for ranging, and a little googling turns up a report from April 1944 which states (on p. 58) that it was even more inaccurate for line than the periscope, and in addition, was hard to see through, both ergonomically and in terms of image quality - in short, Shermans with this modification were still useless in the direct-fire anti-armour role...

Like I said, the Sherman is essentially an SPG...

Even in July 1944, even in May 1945, there were still Shermans in combat units in which the turret-top periscope was the only gunner's optic; if the coaxial telescope was not actually any improvement, that may explain why they were not prioritised for upgrading...

The M55 coaxial telescope was eventually superceded by the M70 series, which are said to have been an improvement, and this may have been the case; but I don't know when they reached combat units or whether they were really any more accurate for line, so anyone with detailed insights is encouraged to share them...

For comparison and contrast, I think most British tanks had a very simple coaxial sight with a crosshair for point-blank AP fire, presumably aligned with the gun to a reasonable degree of accuracy, and graded to allow basic deflection shooting against a moving target - but if you wanted to range out by elevating the gun, I think you just had to guess and sight by eye using a simple observation periscope sans reticle; the first exception serms to be the telescopic sight on the Sherman Firefly and Achilles, combining a British deflection crosshair with an American-style elevation reticle - no idea how they compared for accuracy, though...

(My own suspicion, and it's nothing more than that, is that at least part of the problem with the M55 was the Sherman's unusual mantlet design, which looks like it would have made it hard to keep a coaxial sight aligned; if so, the 75mm version of the M70 and even the Firefly would presumably have had similar issues to the M55, and only the 76mm Sherman with its redesigned mantlet would have been a real improvement...)

It is based on ~40 years of reading and listening about the ww2 aircraft, both in vernacular as well as in foreign languages - English, German, Russian (sprinkled a bit with French and Italian books and magazines).

Aye, I recognized your name as someone who I've read a ton of informed commentary by over many years...

If you really think that A-1 have had only 4 forward-firing LMGs as armament, as well as that 801D has anything to do with A-2, perhaps some further reading on the Fw 190 is in order.

Yes, I was actually hoping for some recommendations... maybe that wasn't as clear as I'd thought?

Haven't I supplied the link of the site with big numbers of tests and performance encounters days ago? Alas.
See here, for a good measure: link (scroll to the bottom table)

Yes, you have supplied that link, and I've been quoting the numbers from the site; the short answer is that the speeds quoted in that table are with the Merlin 46, and are rather less than the ones on the other performance tests for the Mk. V quoted there, which generally use the Merlin 45, and have a lower full-throttle altitude and a slightly higher top speed...

Does this mean the Merlin 46 underperformed? Or was it designed not for a superior headline top speed, but for better performance at higher altitudes around 25,000-30,000ft, which it does seem to have had? You and some other people can comment with more authority than me...

 

[planespotting]

(next bit!)

Good, we will all now stop presenting the German aircraft performance data, since a ship performance data was done, according to you, at an inappropriate loading condition, so the aircraft data is uspect. By the way, just to be sure you know, the USN allowed seawater into ship fuel tanks as the oil was burnt, keeping the ship at roughly the same displacement and thereby enabling heavier armament (top weight), the RN did not, hence quotes of RN destroyers as top speed 32 knots full load, 36 knots light load. Given how many references quote the RN destroyers as 36 knot ships, I have just invalidated allied aircraft test performance results, if I want to.

Compare like with like, the initial proof of maximum performance trials with new aircraft, test pilots etc. or the results from aircraft after or during squadron service, the latter will normally be less. Similarly a warship will be progressively slowed down the longer it goes without a hull clean.

Not an "inappropriate loading condition", a completely fictional one.

Hence, I have an intrinsic lack of confidence in contextless performance graphs; the RAF tests are more informative and seem easier to understand - the performance figures for the squadron-service fighter of 1942, flown to the practical performance limits rather than the official redlines, are lower than the official German numbers, whereas the comparatively good results for the Jabo appear to be obtained by performing a series of separate speed/climb runs in various altitude brackets and pushing the engine to an impractically hot limit, plus, as it turns out, it's a lightweight plane with just two cannon...

On the Sherman versus the 75mm on a half track.

A main advantage to tanks is they are bullet proof, good to hide behind as you advance, good to avoid exposing the gunners to enemy small arms fire, and the turret can be trained, instead of the half track needing to be pointed at the target. Finally it is notable the idea is the allied system would work so well that the troops could advance without vehicle support and call in effective artillery fire kept out of German sight comparable to having tank support and the Germans would be obliging in terms of allowing targets to be located. A major attribute of a good break through tank is reliability, able to go further into the enemy rear, the Red Army liked the Sherman for that.

My first choice would be to have vehicle-mounted artillery scoot up into a convenient position beyond the opposition's anti-tank perimiter and unload, then move away - this is where my preference for the M3 half-track with the 75mm portee comes in...

And if that doesn't work, why are you placing advancing infantry in the open behind a line of obvious targets? Wouldn't it make more sense to have light infantry work their way forward using cover, looking for ways through or around the perimiter?

But if you really need assault armour, surely the role is better served by a low silhouette, a direct-fire gunsight, tight-turning manoeuvraibility and an ability to wade over mud and climb through rubble - a Valentine, a Cromwell, or a Churchill, for example...?

Perhaps showing you have looked at Morgan and Shacklady would encourage people.

Thanks for the book recommendation - just the sort of thing I'm looking for!!

Ignoring the obvious problems with distances, flying to London means over land areas that have raid observer systems in place, unlike the salt water areas around Britain. Now please define rather closer and a lot of. Target list and distances.

Taking a tip-and-run target I'd just been reading a reference to, Torquay in Devon is 100 miles from Cherbourg, compared with about 90 miles from Calais to central London; the same range applies from both Luftwaffe base areas to targets in Sussex like Brighton, or to Southampton; obviously, there's a group of targets in Kent which are much closer to Calais, and some on the Isle of Wight and the Dorset riviera that are a little closer to Cherbourg; but London is, as I said, inside the envelope of normal tip-and-run sorties.

You could be right that London had better ground-intercept systems, though I'd have thought that Chain Home Low would be more readily able to detect low-flying intruder aircraft over the Channel than GCI would in the ground clutter of the Home Counties...

Racks removed?

Probably, yes; it's described in the report as "standard", as opposed to with stores, and the pylons for the wing stores are specifically removed when testing different stores configurations, while photographs of the plane during its test flights show the centreline rack off as well...

Regardless, that doesn't really change the point about the test regime, which seems designed to get maximum speed results without regard for realism...

When a new type emerges the prototype/initial production is sent off to be tested and these become the official performance data, test establishments did a lot of other testing, including reported rogue aircraft for example.

Indeed. The way the various tests for the Spitfire Mk. V are phrased, they sound like they're just taking production planes - and I wouldn't have thought there would be any way to manipulate the performance limits with highly-finished prototype airframes, or unrealistically hot-running engines...

No, your focus is on the fighter bombers, a minority of the Fw190 sorties in the west in 1941/43, everyone else is on the air combat results, which show the Fw190 had a decisive performance edge over most of what it faced into early 1943.

I've not yet found any informative sources on the "air combat results", and by "everybody else", you're excluding the tradition of non-technical British narratives that focus exclusively on the Jabos, and that people like me have read...

I was really just hoping people would respond by recommending better sources that detailed the "air combat results" you're referring to...

The squadron diaries are online at the British National Archives.

</Kosh> "Yes."

A fine example of reputational destruction by adjective. The sloped front plate, the fast turret tracking, the range of useable terrain, the effective HE round.

I'm not sure why you think the glacis, the mobility or the HE round are anything special; the powered turret traverse, though it does seem to have been comparatively reliable, wasn't especially fast, and I'm not sure how good it was at the all-important detail of handing-off to the manual system for precise aiming (its speed might have actually been a disadvantage)...

And at this point I ask myself a semi-obvious question, and discover that the main problem aiming the Sherman is that you can't simply spin the whole vehicle round in a couple of seconds by braking or reversing its offside track... which in turn explains why its gearbox is so reliable, because it lacks the basic precision-steering functionality expected of a tracked AFV...

(And, while looking into this, I also discover that the Panther can be skid-steered by braking the offside track, which isn't pretty engineering, but is easier on the notoriously pretty engineering of the transmission...)

I assume those were for humour.

I'm using a bit of a redactio ad absurdum, and hoping that it will be entertaining whether the reader agrees or not, certainly; but I wouldn't have said it if I didn't mean it...

The altitudes were retrofitted as reasons for a given outcome, please do dig up the information before replying again.

No, they're the altitudes that were implied in your own point; you pointed out, based on what is evidently a very deep and impressive knowledge of the source material, that Allied planes were not regularly flying above about 15000ft in that context; I'm still puzzled why that means they would necessarily be intercepting German ones which tended to fly below about 5000ft, but would be happy to hear a straight answer or a book recommendation...

Complications like for example how many sorties did the various units undertake? The allied interdiction campaign meant the Luftwaffe airfields rapidly had fuel, ammunition and spare parts supply problems, or even started with them, also bombed airfields tend to have reduced operations even if supplies are available. What remained of the Luftwaffe fighter force was down to 50% serviceability at the end of June. Easy to avoid combat losses if there are few combat sorties. A given unit will have runs of few or heavy casualties, the "Bloody Hundredth" comes to mind in the USAAF, 5 Luftwaffe fighter gruppen had to be withdrawn by June 11 due to losses.

Well, as you could have found out if you'd read through the links, the low-level sources I have easy access to state that:

* IV./JG 3, arriving on 8th June, flew two large-scale sorties against the invasion fleet on 9th June, and at least one more each day on 10th and 11th, with no combat losses then or over the next several days, though their maintenance readiness suffered due to the fact that they'd arrived ahead of their ground crew; they were not pulled back through any "losses" (though incorrect statements to this effect do often appear in narratives), but because these Sturmbock interceptors shouldn't have been deployed as close-support Jabos in the first place...

* I./SKG 10, already in Normandy, is attributed a tempo of two to five Jabo missions per day across June and July, variously directed against the fleet, beaches and bocage; notwithstanding a heavy attack on their airstrip on 11th June, they also managed to fit in a night-bombing attack on London that night; total aircraft losses of 20 planes in two months are stated, without any particular details...

* III./SG 4 were more heavily hit, but the details, more readily locatable online, show that much of the attrition came from Allied fighter sweeps bouncing them during repositioning flights on D-Day, when at least some of them were flying with mechanics as passengers in the rear fuselage (seven shootdowns) or ground-attacks on their airstrips (at least fifteen planes knocked out), compounded by the fact that their ground crew were still redeploying by truck and Ju 52, which slowed the repair of damaged aircraft; they nonetheless managed three sorties a day, normally flight-sized but occasionally rising to nearer squadron strength, beginning immediately after their arrival on the afternoon of D-Day, and continuing on 7th, 8th (when fighter escort started to join them) and 9th, after which they were halted through Allied strafing and bombing rendering their airstrip unservicable; an attempt to resume sorties on 11th ended when their takeoff coincided with being bounced by Spitfires; though apparently intimidated by the numbers of Allied planes, they recorded comparatively few losses during sorties - with no more than six shootdowns (and possibly as few as four), not counting the four caught at takeoff on 12th June (I'm not quite clear how many of these were written off); on 18th, after several days of inactivity, they were ordered south again to resume anti-partisan attacks.

Yes, this is only a glimpse, but insofar as these are the details visible to me, they suggests that Fw 190 Jabo missions over Normandy were comparatively undisturbed by Allied fighters (which was the perception I had to begin with); ground attack on airstrips was a more significant threat if the details of III./SG 4 are anything to go by, but some units seem to have been more resilient against that as well...

Is that the whole story? I don't know. Were there, for example, days or even spans of days when SKG 10 flew no sorties? What else should I look at to get more information?

And to be clear, even if I'm right, I don't think that either "tip and run" or these sorties over Normandy were an effective form of attack, just that they were not interdicted effectively. The difference is that in 1941-1943, over the Channel with nothing else going on, the RAF noticed their ineffectiveness and it seemed like an existential crisis; in 1944 over Normandy, with huge parades of stripe-winged fighters in the sky and lots of other things happening, they assumed they'd solved the problem, and the fact that the same thing was stilll continuing underneath their sweeps went largely unregarded...

How many ground attack sorties did the Lysander do in France in 1940? How many sorties in total? They were short range reconnaissance units, how much of the Luftwaffe effort was intercepting these? A large percentage of RAF losses in France were abandoned aircraft. As soon as possible the RAF phased the Lysander out, replacing it with P-40 and P-51 in Britain and other fighters in the Middle East.

These are questions worth asking; but I'm not sure how they shake the fundamental point that abandoned planes seem to have been miscounted as air combat losses...

And I had no idea that the Lysander had a PR capability! I'd taken them to be simply spotter/liaison planes, in which role they were replaced by the Army getting its own Taylorcraft Austers, and close-support aircraft, though I'm not entirely clear whether dive-bombing with two 250lb SAP was actually part of their designed role...

In the fighter role 1941 to 1943 the Fw190 was shooting down allied aircraft at a much higher rate than allied aircraft were shooting down Fw190. In the fighter bomber role the Fw190 was hitting coastal targets and even then taking overall losses that were long term unsustainable, but shooting down few allied aircraft. No wonder you have not seen any specific evidence given the logic of the comparison. And since the Bismarck rule exists you are unlikely to ever see such evidence.

I'm actually looking for recommendations for sources which contain useful detail on these things; if the answer's something like "unpublished Luftwaffe war diaries", that's fair enough...

This comes across as conclusion written, evidence now sought to back it up. While there were plenty of misidentifications the Fw190 had a lot of obvious differences to the Bf109.

No, it's a suggestion about a misinterpretation, an off-the-cuff hypothesis, a target I'm towing for gunnery practice...

And I'm emphatically not suggesting that RAF pilots were visually confusing the Fw 190 and the Bf 109, rather wondering if the RAF more generally might have been misattributing increasing successes by JG 26 to the obviously new and distinctive and fast-manoeuvring Fw 190, and underestimating the impact of the equally new-and-improved but much less visibly distinctive Bf 109F...

(and still more to come!)

 

[planespotting]

(... and the dramatic conclusion!!)

Notes from a discussion on the Sherman, mostly by other people.

I'm not sure I understand why you're quoting all this, but thanks anyway!

The 47 degree sloped front plate, there was an increase in thickness (2 to 2.5 inches) plus the elimination of shot traps and the extra slope to improve protection. Thicker glacis. Wet Stowage (but not for the 105mm or Jumbo versions). The 76mm gun, the 75mm versions with the protection improvements comprised around 40% of production January to May 1944, and 100% thereafter. All 76mm versions had the improvements. Also better optics. During the production run there was quite a bit else that happened. In the M4A1 casting quality was notably better, improving protection, the M4A3 glacis was probably at least a 50 percent improvement over the previous, ammunition stowage was better, and so on. Despite the lack of wet stowage and use as direct infantry support the 105mm Shermans of 12th Army Group had about a third the loss rate of the other Sherman types in 1945. Different usages were seen between 1st and 3rd Armies, from 20 July 1944 onwards the former loss percentage rate was about three 75mm to two 76mm, the latter one 75mm to two 76mm, with 9th Army was closer to 1 to 1.

Some of the modifications, like the removal of the two vision slits, certainly strengthened the armour, but didn't change the basic point that the glacis was a large target with an overcomplex structure, or do anything about the tall, vertical sides...

And I'm not sure what the statistics are supposed to say, except that a 105mm howitzer designed for indirect fire at (I think) 12,000 yards and assigned to a reserve platoon with the battalion HQ will usually be further back beyond the opposing direct-fire perimiter than a Schneider soixante-quinze in a combat company, and thus intrinsically less likely to get shot up; the real question is how regularly did they engage, and at what ranges...

Early production M4 with 75mm were manufactured with the M38 Telescope with M4 Periscope, then went to the M55 Direct Telescope and the M38/M4, and finally the M70F Direct Telescope and the M38A2/M4A1 Periscope (M4A3). The M4A3E2 was manufactured with the M71G Direct Telescope and M38A2/M4A1 Periscope. M4 76mm were manufactured with the M71D Direct Telescope and M47A2/M4A1 Periscope.

The M71-series was designed for the 76mm, except the "G" which was a one-off modification designed for the 75mm in the M4A3E2 since that tank utilized a modified version of the 76mm gun mount and shield. The M70-series was for the 75mm, again except the "G" which was utilized in the M10. The ultimate 76mm sight during the war was the M71F and for the 75mm it was the similar M70F. The M71F didn't become available until Q3/44 in the current production and in limited quantities for retrofitting to existing vehicles.

The M10 was manufactured with the M70G, the M18 with the M71D, but probably also utilized the M71F. The M36 utilized the M76D. It should be noted the tank destroyers received better optics earlier than the Shermans did and that some older vehicles were modified to take the better optics. The actual differences between the later types for the 75mm, 76mm, and 90mm were all incremental improvements, the basic design of the telescopes were similar, but with different reticules for the different gun characteristics.

The original periscopic sights were pretty decent, but the complicated linkage made them difficult to keep aligned with the gun and contributed to inaccuracy. And the original direct telescopes were awful, poor field of view, single power IIRC, and it was almost impossible to see the graticules in anything approaching less than perfect lighting conditions. The second generation optics were much better, especially the direct telescope, which had a better field of view than the German, two magnification settings, and much improved light characteristics. Comments in the field were that they were just about - but not quite - as good as the German.

As I said above to someone else, most of these are observation periscopes and ranging optics; as you say, the M55 was "awful", and only the M70 series might have been proper gunsights that allowed a Sherman crew to accurately line up a shot against another vehicle, but even then I'm unsure of whether they had the required accuracy...

For the period 20 September 1944 to 20 February 1945 in 12th Army Group the tank loss figures indicate for every 1% of M36 strength lost, 1.8% of M18 and 2.7% of M10 strength was lost. Almost, but not quite 1 to 2 to 3. While the numbers here are a guide, and certainly overestimate the M10 vulnerability, it is reasonable to assume that in fact the extra speed did keep M18 losses below M10 losses, and the 90mm gun on the M36 enabled an even lower loss figure.

Or the different figures could equally be to do with the different deployment of the types - five minutes of googling shows that the M10 fought widely throughout this timeframe, and provided an important proportion of the armoured support for US infantry divisions, while the M18 was initially restricted to a handful of armoured divisions in the Third Army, and the M36, although deployed slightly earlier in the Mediterranean, only entered combat with 12th Army Group in December. These figures do not reflect use in the same sort of unit, or attrition over the same timeframe, and they may be further distorted by counting units converting to the M18 and M36 but not yet deployed in combat.

Of course, these statistics were presumably produced by some hard-working and sincere US Army type around 1945, who did not have the advantage of the depth of information on individual TD unit histories that's available on the modern internet to properly control the numbers in the way we, more distant from the action, can do from the comfort of our armchairs; just as importantly, none of this means any of them was a bad TD, and maybe it's just patriotism that makes me think that the Achilles has a better gun and the Archer places that better gun on a better chassis...

planespotting

For all things Sherman you need to spend some serious time on the Sherman Minutia website. Its evolution between the 1942 prototype and the late 1944/45 production variants is remarkable. All the versions, engines, guns, suspension, turret, individual factory features, production data, etc, etc can be found there.

Sherman minutia homepage

The following books are also worth acquiring

Sherman: A History of the American Medium Tank: Amazon.co.uk: Hunnicutt, R.P.: 9781626548619: Books

Buy Sherman: A History of the American Medium Tank Reprint ed. by Hunnicutt, R.P. (ISBN: 9781626548619) from Amazon's Book Store. Everyday low prices and free delivery on eligible orders.

www.amazon.co.uk

Armored Thunderbolt: The U.S. Army Sherman in World War II eBook : Zaloga, Steven: Amazon.co.uk: Books

Armored Thunderbolt: The U.S. Army Sherman in World War II eBook : Zaloga, Steven: Amazon.co.uk: Books

www.amazon.co.uk

US Tank Destroyer history and development is a wholly different line of study.

https://www.armyupress.army.mil/Portals/7/combat-studies-institute/csi-books/gabel2.pdf

Thanks for the links - I know the website, and I've read both Hunnicutt and Armoured Thunderbolt in the past, and there's also theshermantank.com, which is very useful on smaller fittings like the gunsights; but they're only useful as far as they go... see above on what the various gunner's optics actually do and don't do, for instance...

Spitfire Mk VA X.4922 Report

The trouble with the Spitfire is you have a plethora of engines, props, guns, exhausts, snow shields, gun blisters, gun shrouds, barrel stubs, boost ratings, RPM ratings, fuel octane numbers and fit and finish, the list goes on. This one did 375mph so very close.

Aye, the top-speed figures quoted for the Merlin 45 seem notably better than those for the Merlin 46...

 

[Deleted member 68059]

All informative, and appreciated (I assume that part of what this means is that the notional figure for boost is actually a gross overstatement at higher altitudes, but also that the lower ambient pressure of the surrounding air will reduce its heat-loading properties and the cooling efficiency of the engine); but I'm still not sure if this has some significance in the relative performance of the Spitfire Mk. V and Fw 190 at these altitudes that I'm failing to grasp

I dont think you`re going to get very far with any of this unless you understand how superchargers work >


View: https://youtu.be/Pm4SaAnPtYI

 

[ThomasP]

Hey planespotting,

1. My brief description of the early Sherman gunsights was actually in support of your original statement re the poor sighting ability of the periscopic/indirect gunsight. Many people are not aware of the problems/types of sights used in the early M3/M4 tanks.

2. One of the reasons you are getting somewhat derogatory replies is due to statements like:

"The Sherman's 75mm AP round is a lump of low-grade steel shaped like a late-Victorian HE shell, and fired at the muzzle velocity of a late-Victorian infantry-support gun; the M61 APCBC version ought to improve range/velocity somewhat over the basic M72, but it's still dressing up a primitive shot in fancy clothes; everyone else making AP rounds in the early 1940s went for absolutely fierce muzzle velocity, or more sophistication in design and/or metallurgy..."

The only thing partly accurate in this statement is the part "everyone else making AP rounds in the early 1940s went for absolutely fierce muzzle velocity,". But even this only applies to the UK after their early-war 2pdr AP Shell (actually APHE) and AP Shot (relative to its brittleness due to manufacturing quality issues) and to the German APCBC after their 75mm L/42-L/48 entered service. The US, UK, and Soviets all considered the German APCBC superior to their own early- to mid-war projectiles.

The Soviets's early 76mm guns on the KV-1 & T-34 actually had worse exterior/terminal ballistics than the US 75mm M2/M3, and their early-war projectiles were of poorer quality in general. The Japanese and Italian 75mm long-barrel guns of the early- to mid-war period were of the same approximate performance as the US gun. The Japanese did produce some significantly better 75mm guns late-war, while the Italians never fielded their higher velocity 75mm guns to any degree(I think, but could be wrong). As mentioned up-thread, the US went to a 76.2mm gun (either the 3" or the 76mm), but the projectiles were basically 75mm rounds, just modified for the 76.2mm diameter and for the higher velocities (ie bigger cartridge cases, modified driving bands, etc). And of course the UK went to their 17pdr in the mid- to late-war.

The US 75mm M61 APC (UK designation APCBC or APCBC-HE) with which the Lee/Grant and Sherman entered the war was a very good projectile. Until the US 76mm and UK 17pdr entered service the only ~75mm APCBC considered superior (by the US, UK, Germany, Soviet Union) to the M61 was the German 75mm APCBC-HE. The only problem with the M61 round was unreliable fuzing in the early production period (to the point where the Uk requested only unfilled projectiles until the later-war (post D-Day?). Obviously the lower velocity of the US 75mm M3/M3 resulted in poorer terminal ballistics/penetration vs the German 75mm L/43-L/48 guns.

And the M72 AP Shot was a quality uncapped projectile. The M72 was in response to the fact that in general AP Shot with approximately the same weight as the penetrator in the corresponding APC/APCBC projectiles performs better agains Homogeneous armour than APC, while APC performs better against Face Hardened armour than plain AP Shot.

And re the US M48 HE round - the UK, Germans, and Soviets, all considered this round superior to their own 75mm-76mm HE rounds.

The Germans were the only country using tungsten-core projectiles until the US/UK/Soviets came out with their APDS/HVAP/HVAP late-war.

(I do not have info on what the Japanese and Italians thought of the US M48/M61/M72 rounds.)

NOTE Wiki implies that the M72 AP Shot was in use before the M61 APC. This is incorrect, and the fact is borne out by combat records, manufacturing records, and that the manuals upto late-1942 (and possibly later) do not include the M72 in their ammunition sections. As an example, the May 1942 manual for the 75mm M2 as used in the Lee/Grant lists only the M61 APC and M48 HE as Service Rounds (along with 1 drill & 2 practice rounds - one of which is an unfilled/unfuzed Mk I HE). The M3/M4 tanks never saw combat with a different AP Shot prior to the M72.

There was a pre-war SAP Shot from the WWI period that is listed in some ordnance manuals, but it was out of service by the end of 1941 - ie before the Lee/Grant or Sherman entered service. They did have one earlier HE round (the Mk I) that was used to a limited degree in the early-war until supplies of the M48 were sufficient, but most Mk I HE rounds were shipped to the British and Soviets.

 

[ThomasP]

Addition to the above:

If you end up researching what I posted above about the M72 AP Shot availability, be aware that there are digital copies of the May 1942 TM9-305 75mm M1897 field gun manual available online with ammunition sections that include the M72 round. The manual has, however, been updated with the 1944 ammunition section - ie the original ammunition section listing the ammunition types available has been repoved and replaced with the later version - which is why the ammunition section has 2 page 13s. Why this manual (and/or others?) are not clearly marked properly as to the updates I do not know.

 

[Shortround6]

I won't go into any more Sherman detail than this, but since you are the one who claims they can't trust trials or test figures from anybody because of the Bismarck speed figures.

The French navy adopted a Schneider 75mm gun in 1908 as the secondary armament of the Danton-class battleships; as a weapon it didn't have that much commonality with the modèle 1897, but its M1910 ammo could be swapped over, and was adopted, faute de mieux, as an anti-armour round for the mle1897 around 1918...
I suspect that the M1910 ammo isn't actually strictly an AP round, more of an all-rounder that emphasises penetration and fragmentation over blast; so-called "splinter damage" (i.e. frag from near misses detonating on the sea surface) was seen as an important weapon in the original context...
And you need indirect fire for range, as you're expected to engage the torpedo boats at around 8,000 yards with significant elevation on the gun...

The Schneider 75mm gun 1908 was 62.5 caliber length gun and used a bigger chamber than the old US 3in Naval and coast artillery guns. You might be able to swap the projectiles but projectiles are NOT ammunition/ammo or rounds.
In this case the faute de mieux was pretty poor indeed, but since Nobody's tank armor was very thick in 1918 the standard 75mm naval HE projectile worked. Mainly because the nose fused mle 1897 would go off on impact. Which still worked on most of the armor vehicles of 1918. Naval shell used based fused projectile.
There were few, if any, AP projectiles for small naval cannon. Small being between 4-5in (100-127mm) since at naval ranges (3000yds or more) you didn't much armor to keep them out but on the other hand, very few steam torpedo boats or destroyers had any armor at all and even light cruisers only had very limited areas of armor. Hull plating is not armor.
The standard Schneider 75mm gun 1908 had a shell that contained 0.90 kg of Melinite (picric acid) and was very much a HE shell.

Now you seem to be confusing indirect fire and direct fire.
Indirect fire was only used for shore bombardment for navies. Indirect fire is when the crew firing the gun cannot see the target and when corrections are made by an observer that can see the target and has communication with the guns.
Indirect fire has nothing to do with arc the projectile takes on the path to the target.
Direct fire is NOT point blank fire. The Schneider 75mm gun 1908 had a max ordinate of 12 meters at 2000 meters range.

In 1908-1910 they barely were able to engage the main battleship guns at 8000 yds let alone the anti-torpedo boat guns. The little guns would shoot that far but it was a total waste of ammo.

The Schneider 75mm gun 1908 was actually a very close equivalent to the US 3in gun that wound up being used in as the 3in AT gun and the gun used in the M10 which helps explain why very few people were interested in using such guns in 1940-42 tanks. You need a bigger tank than they wanted to build.

The US 76mm gun was almost 1/2 the weight of the US 3in gun (better steel and construction technique) and used a smaller cartridge case and smaller powder charge (new propellent) even though they used the same projectiles.

A lot of the other stuff you have written is similar nonsense but you are the one who doesn't want to use test figures.
Test figures may not be accurate in the field but at least they are a starting point.

 

[tomo pauk]

Yes, I was actually hoping for some recommendations... maybe that wasn't as clear as I'd thought?

In English language, the book by Smith and Creek is one of most current (and at outrageous price). Another one might be by Dan Sharp.
In German language, Rodeike's book (surprisingly normal price).

German-language Wikipedia article is a very good start.

Yes, you have supplied that link, and I've been quoting the numbers from the site; the short answer is that the speeds quoted in that table are with the Merlin 46, and are rather less than the ones on the other performance tests for the Mk. V quoted there, which generally use the Merlin 45, and have a lower full-throttle altitude and a slightly higher top speed...

You can take a look at "RAE Tech Note No Aero 1273 Flight". They blame the low speed figures of the Mk.V vs. what was deemed realistically possible on two 'categories' - one was that appendices (BP glass, stone/ice guard, draggy/less efficient exhausts, protruding cannon barrels etc.) were adding to the drag, and another was lousy fit & finish (loss of 8.5 mph on the example they were testing; up to 11.2 per their experience on other Spitfire Vs).
Perhaps we'd be well advised to look at the interval of top speeds at ~19000 ft in the real world, where one fighter type (Spit V) was doing 356-375 mph, and another (early Fw 190A) was doing 375-400+ mph, and not opt to pick the best speed figure of one type and worst speed of another?

Does this mean the Merlin 46 underperformed? Or was it designed not for a superior headline top speed, but for better performance at higher altitudes around 25,000-30,000ft, which it does seem to have had? You and some other people can comment with more authority than me...

RR was expecting that Mk.46 will 'elevate' the rated altitude by some 2000-2500 ft vs. Mk.45, thus being a better engine for altitudes above 20000 ft.
They should be also better than Mk.45 above 15000 ft if both engines are using overboost. Unfortunately, I'm not aware of any tests of Mk.46 powered Spitfires where the overboost was used.

 

[Daggerr]

In English language, the book by Smith and Creek is one of most current (and at outrageous price). Another one might be by Dan Sharp.
In German language, Rodeike's book (surprisingly normal price).

German-language Wikipedia article is a very good start.

Rumor has it that the Smith & Creek FW 190 books will have an unchanged reprint later this year. Remains to be seen whether that will actually happen.

Worth considering are also the English language FW 190 books by Dietmar Hermann, an authority on the FW 190 and other FW planes.

If found for a reasonable price Edward Shacklady's FW 190 book, and the FW 190 Haynes Manual may be of interest.

 

[planespotting]

I dont think you`re going to get very far with any of this unless you understand how superchargers work >


View: https://youtu.be/Pm4SaAnPtYI

Oh, I agree...

1. My brief description of the early Sherman gunsights was actually in support of your original statement re the poor sighting ability of the periscopic/indirect gunsight. Many people are not aware of the problems/types of sights used in the early M3/M4 tanks.

I appreciated your reply regardless, and I appreciate the fact you bothered to emphasise this in a followup; but what I'm saying is, the M55 doesn't seem any good either, and I'm not sure about the M70 series...

The only thing partly accurate in this statement is the part "everyone else making AP rounds in the early 1940s went for absolutely fierce muzzle velocity,". But even this only applies to the UK after their early-war 2pdr AP Shell (actually APHE) and AP Shot (relative to its brittleness due to manufacturing quality issues) and to the German APCBC after their 75mm L/42-L/48 entered service. The US, UK, and Soviets all considered the German APCBC superior to their own early- to mid-war projectiles.

The 2pdr is a gun of 1935 though - for the UK, I'm talking about the muzzle velocity of the 6pdr and 17pdr, followed by the "sophistication in design and/or metallurgy" of the Littejohn, tungsten-cored shot and then APDS.

With the Germans, there's the tungsten-cored Pzgr. 40 for the ordinary-velocity guns, applying the muzzle velocity of the 88mm and the 5cm lang to make ordinary Pzgr. 39 useful, and then their long 75mm guns, and a switch to a projectile with a high-carbon ogive and a more ductile body.

The Soviets's early 76mm guns on the KV-1 & T-34 actually had worse exterior/terminal ballistics than the US 75mm M2/M3, and their early-war projectiles were of poorer quality in general.

Where are you getting your information from, out of interest? I've never read much that's seemed reliable, but they're at least supposed to do something clever with their shape; again, an example of "sophistication in design"...

The Japanese and Italian 75mm long-barrel guns of the early- to mid-war period were of the same approximate performance as the US gun. The Japanese did produce some significantly better 75mm guns late-war, while the Italians never fielded their higher velocity 75mm guns to any degree(I think, but could be wrong).

I honestly had no idea until you mentioned this that the Japanese had mounted 75mm guns on tracked chassis, let alone that a casemate SPG actually saw combat, but except for the big flak-derived one they were prototyping in 1945 they're very much 1930s infantry-support weapons; contrast their long 47mm gun, which is definitely emphasising muzzle velocity in the anti-armour role?

And the Italians are using that weird hollow-charge/squash-head ammo, which is another example of exactly what I'm talking about, "sophistication in design"...

The US 75mm M61 APC (UK designation APCBC or APCBC-HE) with which the Lee/Grant and Sherman entered the war was a very good projectile. Until the US 76mm and UK 17pdr entered service the only ~75mm APCBC considered superior (by the US, UK, Germany, Soviet Union) to the M61 was the German 75mm APCBC-HE. The only problem with the M61 round was unreliable fuzing in the early production period (to the point where the Uk requested only unfilled projectiles until the later-war (post D-Day?). Obviously the lower velocity of the US 75mm M3/M3 resulted in poorer terminal ballistics/penetration vs the German 75mm L/43-L/48 guns.

Which other 75mm APCBC rounds are you comparing it to, though? The Italian ones?

And the M72 AP Shot was a quality uncapped projectile. The M72 was in response to the fact that in general AP Shot with approximately the same weight as the penetrator in the corresponding APC/APCBC projectiles performs better agains Homogeneous armour than APC, while APC performs better against Face Hardened armour than plain AP Shot.

Now this is interesting - you're saying they were expetced to do better than M61 against the Tiger and Panther and the Panzer IV ausf. J, at least at short range?

The Germans were the only country using tungsten-core projectiles until the US/UK/Soviets came out with their APDS/HVAP/HVAP late-war.

The British "Littlejohn" tungsten round was designed in 1942, albeit only for the 2pdr...

NOTE Wiki implies that the M72 AP Shot was in use before the M61 APC. This is incorrect, and the fact is borne out by combat records, manufacturing records, and that the manuals upto late-1942 (and possibly later) do not include the M72 in their ammunition sections. As an example, the May 1942 manual for the 75mm M2 as used in the Lee/Grant lists only the M61 APC and M48 HE as Service Rounds (along with 1 drill & 2 practice rounds - one of which is an unfilled/unfuzed Mk I HE). The M3/M4 tanks never saw combat with a different AP Shot prior to the M72.

Thanks again for the insight... I've seen claims that M72 was in production from early 1942, but I don't know whether they're based on anything beyond internet nonsense...

Addition to the above:

Thanks again!

The Schneider 75mm gun 1908 was 62.5 caliber length gun and used a bigger chamber than the old US 3in Naval and coast artillery guns. You might be able to swap the projectiles but projectiles are NOT ammunition/ammo or rounds.

The "shot" rather than the "round", then - I'm more used to an earlier period, where "round" and "shot" both mean the cannonball, and fixed ammo involves wedging the ball onto a wooden sabot...

But yes, same projectile, same M1910 designation, just a different brass cartridge / propellant fill attached to the back end depending on whether you're shooting it from a battleship, a Schneider soixante-quinze or the hull gun of a Char B1...

The standard Schneider 75mm gun 1908 had a shell that contained 0.90 kg of Melinite (picric acid) and was very much a HE shell.

There may have been a 900g HE round, but I suspect that's just a copying error, as the M1910 is APHE/SAP with a 90g filler. Here's a diagram...

For contrast, the gun's contemporary British counterpart, the 12-pounder QF, uses a variery of longer but lighter-weight shells with a thinner casing and lot more filler - here's a convenient wikipedia screengrab showing the base-fused black-powder "common pointed" and various nose-fused lyddite "common" shells; two types, I'm not sure which, have filler weights listed by Friedman as 1lb 1 oz and 1lb 3 oz, which work out either side of 500g...

Now you seem to be confusing indirect fire and direct fire.

Naval "director fire" is indirect fire. A central control room selects the target, calls in range and elevation to the group of guns, spots the fall of shot, and corrects the aim.

The direction system on the Danton class was amusingly primitive, but it was the way they were designed to fight, and the armament itself was logical in a fairly French way - it was supposed to be used one calibre at a time, with the 75mm to repulse torpedo boats (which you need to be shooting at outside torpedo range, which at the time of their design already meant 5,000-yard distances, that being the main thing that was pushing gunnery wider in the dreadnaught era); the 9.4 inch guns in the side turrets were to fight opposing capital ships at ranges of 6000-8000m (7000-9000 yds), aiming to mission-kill them by shattering their unarmoured superstructure with relatively rapid fire rather than penetrating the armour, and the 12-inch main guns were to sink the wrecks thus created with slower shooting at close range...

In English language, the book by Smith and Creek is one of most current (and at outrageous price). Another one might be by Dan Sharp.
In German language, Rodeike's book (surprisingly normal price).

German-language Wikipedia article is a very good start.

Danke! My German is appalling, but there's a research library within a short walk that has Smith/Creek and Sharp...

You can take a look at "RAE Tech Note No Aero 1273 Flight". They blame the low speed figures of the Mk.V vs. what was deemed realistically possible on two 'categories' - one was that appendices (BP glass, stone/ice guard, draggy/less efficient exhausts, protruding cannon barrels etc.) were adding to the drag, and another was lousy fit & finish (loss of 8.5 mph on the example they were testing; up to 11.2 per their experience on other Spitfire Vs).
Perhaps we'd be well advised to look at the interval of top speeds at ~19000 ft in the real world, where one fighter type (Spit V) was doing 356-375 mph, and another (early Fw 190A) was doing 375-400+ mph, and not opt to pick the best speed figure of one type and worst speed of another?

The difference, as I see it, is that the early Fw 190 has a known gap between sustained performance and theoretical limits that leads me to emphasise the lowball numbers, but that's an attempt to obtain "realistic" figures for a squadron-service plane, not a wilful attempt to distort the results; I was setting them against the performance website's whole range of numbers for the Spitfire Mk. V with the Merlin 45 (which appear to be tested at its ordinary performance limits and weight, and as you say, always has a fairly unfinished airframe)...

RR was expecting that Mk.46 will 'elevate' the rated altitude by some 2000-2500 ft vs. Mk.45, thus being a better engine for altitudes above 20000 ft.
They should be also better than Mk.45 above 15000 ft if both engines are using overboost. Unfortunately, I'm not aware of any tests of Mk.46 powered Spitfires where the overboost was used.

Wait, are you now arguing that the Merlin 46 numbers are understated?

Funnily enough, I'd definitely be prepared to consider the possibility that a Fw 190 has an edge over a Mk. V with a Merlin 46 at altitudes around 15,000-20,000ft; the question then becomes how many Merlin 46 aircraft were engaging the Fw 190, and if so, whether this was any sort of a good idea...

Rumor has it that the Smith & Creek FW 190 books will have an unchanged reprint later this year. Remains to be seen whether that will actually happen.

Worth considering are also the English language FW 190 books by Dietmar Hermann, an authority on the FW 190 and other FW planes.

If found for a reasonable price Edward Shacklady's FW 190 book, and the FW 190 Haynes Manual may be of interest.

Thanks! The nearby research library has Hermann too, and Calum Douglas's book on engines, but not Shacklady...

 

[Geoffrey Sinclair]

Not an "inappropriate loading condition", a completely fictional one.

Bismarck could draw 29 feet at light ship.

Hence, I have an intrinsic lack of confidence in contextless performance graphs; the RAF tests are more informative and seem easier to understand - the performance figures for the squadron-service fighter of 1942, flown to the practical performance limits rather than the official redlines, are lower than the official German numbers, whereas the comparatively good results for the Jabo appear to be obtained by performing a series of separate speed/climb runs in various altitude brackets and pushing the engine to an impractically hot limit, plus, as it turns out, it's a lightweight plane with just two cannon...

It is good to know the German performance data, with new aircraft, done by people fully aware of the technical specifications with a good spare parts and even replacement system were better than the RAF test of a squadron aircraft where a balance had to be struck between the only example's lifetime and finding how good it was, the further the testing being pushed the lower the lifetime.

My first choice would be to have vehicle-mounted artillery scoot up into a convenient position beyond the opposition's anti-tank perimiter and unload, then move away - this is where my preference for the M3 half-track with the 75mm portee comes in...

And if that doesn't work, why are you placing advancing infantry in the open behind a line of obvious targets? Wouldn't it make more sense to have light infantry work their way forward using cover, looking for ways through or around the perimiter?

I suggest you talk to some ground force commanders, you are so far away from reality.

You could be right that London had better ground-intercept systems, though I'd have thought that Chain Home Low would be more readily able to detect low-flying intruder aircraft over the Channel than GCI would in the ground clutter of the Home Counties...

Heard of the observer corps?

I've not yet found any informative sources on the "air combat results", and by "everybody else", you're excluding the tradition of non-technical British narratives that focus exclusively on the Jabos, and that people like me have read...

Sorry, if you have not picked up the information here by now, you are never going to.

No, they're the altitudes that were implied in your own point; you pointed out, based on what is evidently a very deep and impressive knowledge of the source material, that Allied planes were not regularly flying above about 15000ft in that context; I'm still puzzled why that means they would necessarily be intercepting German ones which tended to fly below about 5000ft, but would be happy to hear a straight answer or a book recommendation...

Sorry, if you have not picked up the information here by now, you are never going to. I noted an nominal upper limit, 12,000 feet, you raised it to 15,000 feet and then try to tell the world that is where all the allied fighter bombers were operating, therefore they missed the Germans.

Well, as you could have found out if you'd read through the links, the low-level sources I have easy access to state that:

* IV./JG 3, arriving on 8th June,

* I./SKG 10, already in Normandy,

* III./SG 4 were more heavily hit, but the details,

Well, why reply to someone you know has not read the data? Thanks for deciding I comment without checking. I have noted that some units were lucky or unlucky, and have posted the loss data. So around 2/3 losses in under 2 months is not heavy? E.R. Hooton says for 1944, Luftflotte 3 had a day fighter loss rate of 5.95% of sorties. The western allies considered 5% the maximum long term sustainable loss rate. So did I/SKG 10 do over 400 sorties in the time?

Yes, this is only a glimpse, but insofar as these are the details visible to me, they suggests that Fw 190 Jabo missions over Normandy were comparatively undisturbed by Allied fighters (which was the perception I had to begin with); ground attack on airstrips was a more significant threat if the details of III./SG 4 are anything to go by, but some units seem to have been more resilient against that as well...

I do also see now, undisturbed by allied fighters only applies to in flight a distance from the airfield on a bomber mission. Since you are presumably comparing the loss rates of fighter bombers to the fighters you need to come up with a loss rate for the fighters in flight a distance from the airfield on a fighter mission.

The difference is that in 1941-1943, over the Channel with nothing else going on, the RAF noticed their ineffectiveness and it seemed like an existential crisis; in 1944 over Normandy, with huge parades of stripe-winged fighters in the sky and lots of other things happening, they assumed they'd solved the problem, and the fact that the same thing was stilll continuing underneath their sweeps went largely unregarded...

People tend to become more upset when their country is attacked and the Fw190 performance and targets in 1941 to 1943 made them hard to intercept, things like standing patrols are expensive. And you keep deciding how high the allied fighters were flying in Normandy, when they were at a range of heights. Unfortunately books like the 9th Air Force in WWII by Ken C. Rust and USAAF Jabos in the MTO and ETO by William Wolf assume readers are aware the sorts of altitudes being used given the strafing being done. The 15th Air Force Target and Duty sheets list the altitudes of the 4 and 6 November 1943 fighter bomber operations as 3,000 and 3,100 feet and mostly lower for the January attacks.

These are questions worth asking; but I'm not sure how they shake the fundamental point that abandoned planes seem to have been miscounted as air combat losses...

Or not, depending on the reference. Wood and Dempster have Failed to Return, destroyed on ground, written off and abandoned aircraft, 37 Lysanders in total, 33 in May, 4 in June 1940.

Or the different figures could equally be to do with the different deployment of the types - five minutes of googling shows that the M10 fought widely throughout this timeframe, and provided an important proportion of the armoured support for US infantry divisions, while the M18 was initially restricted to a handful of armoured divisions in the Third Army, and the M36, although deployed slightly earlier in the Mediterranean, only entered combat with 12th Army Group in December. These figures do not reflect use in the same sort of unit, or attrition over the same timeframe, and they may be further distorted by counting units converting to the M18 and M36 but not yet deployed in combat.

So 5 minutes on the internet followed by a story about how maybe could be, not worthwhile. Meantime I used the weekly US Army tank strength and loss returns and the monthly Army Group AFV strength and loss returns. For example the M36 came on strength in the 20 September to 20 October period, 170 around at the end of the period after 2 losses, by 20 November 7 had been lost and 183 were on strength. M18 were in strength before 20 June, but no combat losses reported until the month ending 20 August. The M4 with 76mm gun, first reports on week ending 29 July, 168 operational, 12 losses the next week, the M4 105mm first appearance week ending 8 July, 47 operational 3 lost. Other vehicles covered include the M7 105mm and the M8 75mm.

Of course, these statistics were presumably produced by some hard-working and sincere US Army type around 1945, who did not have the advantage of the depth of information on individual TD unit histories that's available on the modern internet to properly control the numbers in the way we, more distant from the action, can do from the comfort of our armchairs; just as importantly, none of this means any of them was a bad TD, and maybe it's just patriotism that makes me think that the Achilles has a better gun and the Archer places that better gun on a better chassis...

Actually I did the analysis a while ago now, but you put a fictional date stamp on it and wrote a story of how the results should be therefore be ignored. Thanks for making me eligible for a whole lot of old age and veteran benefits, I am sure your solid knowledge will totally overcome the way I look so young for my age. By the way the changing populations, 691 M10 and 145 M18 on 20 June 1944, to 686 M10, 448 M18 and 826 M36 on hand on 20 February 1945 poses the usual statistical problems, also the Ardennes offensive where the US lost the battlefield and so vehicles it could have repaired, like total losses of the M7 105mm 6 June 1944 to 20 February 1945 were 182, of which 105 were the month ending 20 December 1944.

You announced a lack of knowledge on the subject and are more demonstrating how the lack of knowledge is continued. Please do not reply to this message, it is most likely only going to cause further offence.