Fw 190 performance

[tomo pauk]

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)...

(while trying to ignore ending the sentences with ... )

What was the gap, and who defined and proved the gap? And for what specific version of Fw 190?

List of Spitfire V serials that were tested at 350-360 mph, per the above listed RAE paper: W3134 (snowguard - installed in front of the ram air intake - really messed here the thigh up, both in speed and in rated altitude), AA878, AA937, EF644, EN946. Same paper notes that Mk.V was the biggest offender between the three mass-produced Spitfires of the day (Mk.I, V and IX) wrt. fit and finish.

It would've take a bit of nip and tuck, plus more effort into obtaining a better fit & finish for the Spitfire V to perform in the ballpark of Fw 190, unfortunately it was not meant to be, leaving for the Typhoon and installation of Merlin 61s on Spitfires (ironically, with better exhausts, carbs and BP glass installation) to more than equalize the game.

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

No.

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...

Okay.

 

[Shortround6]

Oh, boy. more crap, I am seriously suspecting we are being trolled.

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...

However the change in the brass cartridge/propellent fill affects the all sorts of things, Like the ballistics which govern the AP performance of the shot. It also affects the chamber pressure and burning curve. Using a lot more "propellent fill" means you need thicker barrel walls (for the same generation steel/construction technology) and longer barrels to burn the larger amount powder in or you just waste a lot of it in muzzle flash. Now due to both internal ballistics and to impact physics the same shell design often does not work well at different velocities, even though it may be cheap. see below.

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...

You may very well be right about the expulsive weight.
I see a thick walled shell suitable for a high veleocity gun. Thin wall shells, given the same strength steel had a greater tendency to break up in the gun or just after existing the gun.
Now this is complicated by the type of steel used in the shell and the actual weight of the shell. You can fire a 12 1/2 pound shell faster than you can fire a 14.1lb shell.
This is why the US 3in AT gun and the 76mm guns fired HE shells with less HE than the old French 75 shells, they needed thicker walls to stand up to the firing stresses. but not this amount of explosive reduction. That said the US 3in/76mm HE shells held 57% of the HE (TNT) that the US 75mm HE shells held.

However a lot this stuff works on square or cube. If you want twice the velocity you need 4 times the propellent (or propellent that contains 4 times the energy) as a rough guide.

On the other end (target) you had differences between the heat treatment/alloy of the shell/shot and the heat treatment alloy of the armor. You also had changes in the dynamics of the penetration at different speeds. Below a certain speed and given somewhat normal armor plain alloy steel shot worked pretty well. at a higher speed (or against harder armor) you needed better heat treatment of the shell point (harder) but keeping a less brittle body. You don't really need capped shot unless the impact veleocity (not muzzle velocity) is over 2000fps. rough guide line depending on exact steel and heat treatment of shot and the exact armor. Then the shot starts to fail. The face hardened armor the Germans used threw things off a bit. Capped shot (or shell) works up to around an impact velocity of about 2600fps and then it too begins to fail and then you start needing the exotic shot.
And here is where naval shells depart from tank guns/ammo. A short range shot for even a 1910 torpedo boat cannon is a long shot for a WW II tank battle. They were using the capped shells/shot on the big naval guns before WW I and starting to fool around with ballistic capped shot. The French 75mm 1910 gun was down to 499m/s by the time it got to 2000 meters.

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.

Problem with this is timing. Most of dreadnought battleships were only getting director control for their main guns in 1916, give or take a few years. Some of the odd balls in the far corners of the world only got director control in 1920s. There is quite a bit to get from the prototype systems/parts used the pre war era to fleet use of systems that actually worked.
Director control for the secondary batteries showed up a few years later in the British and German navies and not all of theirs had it by 1918. Some cruisers did not have director control even in 1918. Tertiary batteries were well down on the list. There was also a lot of theory going on in the 1920s and 30s that did not work out in practice. Long range destroyer and anti-destroyer fire was not as easy as they thought.
French were sticking 5.5in guns on large destroyers with ranges of around 20,000 yds. Trouble for the destroyers was that even with a 3 meter range finder they could not spot the shell splashes at over 13,000yds/meters for example.

Words changed meaning with time.

 

[ThomasP]

Hey planespotting,

Check out this site "Tank Archives" for information on the Soviet equipment in particular, but also for other nations.

Whoever is running it has done an amazing job of uploading a ton of original source documents from the various countries, in particular the Soviet Union. You can find a bunch of Soviet war-time tests for various tank rounds (Soviet, US/UK lend lease, German). There are all kinds of tests comparing equipment of the different nations.

re performance of the M61 APC(BC) vs M72 AP

There are various original source documents available online that provide detailed penetration data for the more common projectiles, and even some of the less common ones. An abbreviated source for US projectile penetration vs RH (Rolled Homogeneous) and FH (Face Hardened) armour can be found in the TM9-1901 Artillery Ammunition manual - the 2 pages immediately below are from that manual:

__________________________________________________________________________________________________________________________________

While the following 2 pages are from the Terminal Ballistics Data Vol II Artillery Fire 1944 manual, these are only for the M61 APC projectile. I have the Striking Velocity vs Armor Penetration and Range tables for the M72 AP projectile also - somewhere - but I think they are on my other computer which is in storage right now. The tables for the M72 AP bare out the numbers in the page from the Artillery Ammunition manual above.

__________________________________________________________________________________________________________________________________

You can see the approximate differences in penetration of the 2 different types of projectiles vs RH and FH armour.


re which type would work better vs the German tanks and/or "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 early production Panther used FH armour on it glacis plate, the late production switched to RH armour. I think the King TIger stuck with FH armour. I am not sure what the armour types and distribution were on the Tiger I, though I know the driver's vertical plate was FH armour. The 75mm M61 APC or M72 AP could not penetrate any of the Tiger I/Tiger II/Panther glacis plates or turret fronts at combat ranges. But against the RH side armour the M72 AP would in theory do better than the M61 APC.

Incidentally, the UK developed 3 different armour piercing for the 17pdr - AP, APC, and APCBC - in order to have the best chance of defeating whatever type of heavy armour they encountered. They had a similar range of ammo for their 6pdr for the same reason.

 

[planespotting]

I wasn't really sure how to respond to Geoffrey Sinclair - obviously, he has a tremendous depth and range of technical knowledge, and I wish I could make it clearer that I respect that; all I was really trying to do was get recommendations for which in-depth books were worth reading and any other insights people were willing to share, explain where I wasn't sure I understood a point or felt I wasn't making myself clear, and defend some points where I'm more confident of my own opinion (notably the performance of the Bismarck and the quality of the Sherman); I certainly didn't intend for anyone to lose their hat, but if he doesn't want a reply, then that's what it is...

If anyone else wants to pick up on any related points, do send me a private message; one thing I will ask here, though (because this place is full of surprising knowledge), which is if anyone knows any US units in Twelfth Army Group that used the M36 in combat before December 1944, then I'd be glad of the correction - the nearest thing I've found is 776th TD, which started in the Mediterranean, but by November was in Alsace supporting 7th Army in Sixth Army Group and the French 2e DB...

What was the gap, and who defined and proved the gap? And for what specific version of Fw 190?

The gap relates to the Fw 190A3, and is defined by the "de-rated" engine of the the fighter captured intact by the RAF in 1942 (quoted from information "found in the cockpit" in this report, PDF format), followed by the memorandum of October 1942 (half-way down this page) allowing the restrictions on front-line fighters to be removed.

I'm uncertain about the earlier A2, as I've not yet got hold of the books I need, hence (on one level) the delay in replying to this...

List of Spitfire V serials that were tested at 350-360 mph, per the above listed RAE paper: W3134 (snowguard - installed in front of the ram air intake - really messed here the thigh up, both in speed and in rated altitude), AA878, AA937, EF644, EN946. Same paper notes that Mk.V was the biggest offender between the three mass-produced Spitfires of the day (Mk.I, V and IX) wrt. fit and finish.

Now this is interesting. Because, from the sources that I can find, none of these is a normal Spitfire Mk. V...

* W.3134 as you say recorded 365 mph with a snowguard, which is actually faster than the range being cited - and 371 mph without one!

* A.A.878 was used to test increased boost, reaching 359.5mph at "normal" and 369mph with enhanced boost, at a relatively low full-throttle height. This is pretty much the only figure I've seen that gives such a low number for a Spitfire Mk. V with Merlin 45 in any sort of "normal" configuration.

* A.A.937 was used to test the difference in performance between normal wingtips and shortened straight-ended wings; it's described as though it was somehow removing the ends of normal wings, but from the many available photographs, this is known to have been a straight-wingtip, short-span plane, so presumably had wooden mock tips added temporarily; its speed performance was low in both configurations, quoted at 353 mph at 19,600ft, but cannot be taken as reflective of the speed-performance of a Mk. V with normal wings...

* E.F.644 and E.N.946 were used to test airframe changes, and from the limited information available, not all of these were successful; maybe their top speed was reduced.

Now, obviously, I don't have access to the original document, and maybe there's more to this than what I can see, but my immediate suspicion is that these aren't actually valid examples of the speed range of a production Spitfire Mk. V, and if they were being cited as such, were the numbers being misinterpreted...?

I have no problem with the idea that British documents of this sort might be as unreliable as anyone else's, though in this case, that would mean it's underreporting the performance of the Spitfire Mk. V...

Oh, boy. more crap, I am seriously suspecting we are being trolled.

No, on both points.

However the change in the brass cartridge/propellent fill affects the all sorts of things, Like the ballistics which govern the AP performance of the shot. It also affects the chamber pressure and burning curve. Using a lot more "propellent fill" means you need thicker barrel walls (for the same generation steel/construction technology) and longer barrels to burn the larger amount powder in or you just waste a lot of it in muzzle flash. Now due to both internal ballistics and to impact physics the same shell design often does not work well at different velocities, even though it may be cheap. see below.

That's true (and considerably more technically informed than I'd be capable of), but it doesn't change my point; in French usage, the M1910 designation denotes the projectile, not the back-end... and the same M1910 projectile was used with several very different cartridges, from several very different guns, for everything from shooting at destroyers from dreadnought-era capital ships to shooting at panzers in 1940...

I see a thick walled shell suitable for a high veleocity gun.

You're right about that, a point I'd overlooked - the French naval 75mm modèle 1908 was considerably punchier than its Royal Navy counterpart, the QF 12pdr as used on HMS Dreadnought (L62.5 vs L50, 850m/s vs. 790m/s muzzle-velocity, 2.44 kg vs. 1.25 kg propellant).

Doesn't change the fact that its projectile was then taken over in the anti-armour role for the standard Schneider 75mm infantry gun and the Char B1, each of which used a different barrel, breech, brass-cartridge and projectile fill to deliver it....

And I don't think it changes my argument that there were other reasons for favouring this projectile-type for anti-destroyer work, either...

Not that that's entirely relevant to the point I was trying to make, which is that in the early 1940s, when everyone else except maybe the Japanese was enhancing their 75mm anti-armour ammunition by using an interesting shape or superior alloy or HEAT or sabots or at least a punchy muzzle velocity, or a combination of the above, the US M72 and M61 weren't, and as such, they look (perhaps unsurprisingly, considering the guns they were designed for) like knock-offs of the unusually simple anti-armour round used by the Schneider 75 and Char B1, which was in fact an old anti-destroyer naval round repurposed around 1917 (as to the obvious differences, removing the fill on the M72 reflects British practice, capping the M61 is self-explanatory)...

Problem with this is timing. Most of dreadnought battleships were only getting director control for their main guns in 1916, give or take a few years. Some of the odd balls in the far corners of the world only got director control in 1920s. There is quite a bit to get from the prototype systems/parts used the pre war era to fleet use of systems that actually worked.
Director control for the secondary batteries showed up a few years later in the British and German navies and not all of theirs had it by 1918. Some cruisers did not have director control even in 1918. Tertiary batteries were well down on the list. There was also a lot of theory going on in the 1920s and 30s that did not work out in practice. Long range destroyer and anti-destroyer fire was not as easy as they thought.
French were sticking 5.5in guns on large destroyers with ranges of around 20,000 yds. Trouble for the destroyers was that even with a 3 meter range finder they could not spot the shell splashes at over 13,000yds/meters for example.

There's a difference between "director control", a specific evolution of Royal Navy practice that was then widely imitated, and the more general concept of "director firing", measuring range and angle centrally to provide aiming instructions for the group of guns, which was in place earlier.

For the fire-control arrangements on the Danton class, there's good stuff in Friedman's Naval Gunnery and the recent article on the French dreadnoughts in Warship. Suffice to say, aiming instructions were issued centrally from the "director" in the broad sense of the term.

The challenges of giving proper fire-control to light cruisers and destroyers are to do with design - engine vibration, stability, topweight, and simple available space, and aren't really pertinent to the anti-destroyer armament of capital ships.

Words changed meaning with time.

Yes, they do!! See above!!

Hey planespotting,

Check out this site "Tank Archives" for information on the Soviet equipment in particular, but also for other nations.

Whoever is running it has done an amazing job of uploading a ton of original source documents from the various countries, in particular the Soviet Union. You can find a bunch of Soviet war-time tests for various tank rounds (Soviet, US/UK lend lease, German). There are all kinds of tests comparing equipment of the different nations.

Aye, I'm pretty sure anyone who's ever googled a question about armour in '39-'45 is aware of that site, but honestly, I've not found anything there that answers the specific questions I had about different shell types - the speciifc differences of design between AP rounds seems to be one of those niche topic that even experts don't understand...

Thanks, though!!

re performance of the M61 APC(BC) vs M72 AP

There are various original source documents available online that provide detailed penetration data for the more common projectiles, and even some of the less common ones.

Thanks for those - do you know if these are calculated from actual testing, or some sort of theoretical equation?

Also, I'm amused by "increase muzzle velocity by accelerating the gun to 350 mph using a plane", which I assume is the A-26, but if that's the case, what gun is this? The types that were aircraft mounted were the M3 variant of M1/M116 low-velocity pack-howitzer or the high-velocity M5/M6 shared with the Chaffee...?

re which type would work better vs the German tanks and/or "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 early production Panther used FH armour on it glacis plate, the late production switched to RH armour. I think the King TIger stuck with FH armour. I am not sure what the armour types and distribution were on the Tiger I, though I know the driver's vertical plate was FH armour.

I was meaning that they'd all be RH-armoured, because I didn't think that there would be any face-hardened Panther variants facing the Sherman, though maybe I'm wrong about that; and I'd thought that the Tiger was all RH throughout its production - when you mention the "driver's vertical plate" being FH, do you mean the upright hull plate, or the surround for the driver's viewing embrasure?

Thanks for the reply though, sorry this took so long!

 

[GregP]

The FW190 owned the sky up to and including 20,000ft until the MkIX arrived mid '42, even then it took the MkIX LF to really tip the balance to the Spits favour, don't be under any illusions otherwise.

That's flies a bit against actual combat facts. The Mk. IX didn't lack for superior rate of climb and ceiling. It had a lower roll rate, but roll is only one aspect of maneuverability.
The Mk. IX LF had clipped wing tips and better roll rate, but not enough to match the Fw 190 roll rate AFAIK.

You are dismissing the Spitfire when the Spitfire was one of the best piston fighters ever produced. Better think again, because the Spits maybe have initially been at a disadvantage in the Mk. V model, but not by much. The Mk. IX didn't really need any help when it encountered an Fw 190. It as just fine as long as both pilots saw the other one, I'd call them a really good match with the Spitfire IX being better above 18,000 feet or so and as good if not better everywhere else. The Fw 190 didn't regain much until the Fw 190D came out in Sep 44. At that point, it was a decent higher-altitude fighter, better than the A/F models but, by that point, so were contemporary Spitfires.

 

[ThomasP]

Hey planespotting,

1. The basic penetration results at range were measured, usually with the first test being between 100-250 yds followed by ranges in 250-300 yd increments, and then 300-600 yd increments. As is usually done in these types of documents the results were then graphed and the line 'normalized' for the values in between.

2. Sorry, I do not know if there was a particular airplane envisioned for the 350 mph increase in muzzle velocity. I agree that for in service aircraft the 350 mph might really only be applicable to the A-26, although the B-25 with the 75mm bun was still in service for several years after the war. It may, however, simply be that the test personnel/graph preparers figured that that 350 mph was the maximum foreseeable practical speed of any aircraft attacking with the gun. As far as I know the B-25 usually controlled at about 230-250 mph in a shallow dive when attacking. The Hurricane IID/IV also tried to control to about 250 mph when attacking with the 40mm Vickers 'S' gun.

3. While most of the Panthers produced toward the end of the war had homogeneous armour on the front glacis, there were many still around from earlier production. The Panthers that the US and UK faced on the Western Front were a mix of production types and periods, partly due to many of the tanks they faced having been rotated out of front line service on the Eastern Front and or Italian Front when the units were pulled to the rear for rest, repair, and replenishment.

I do not remember the name of the UK field report concerning the performance of US and UK guns vs the German armour, but IIRC they specifically mentioned the Panthers as having varied glacis armour types. This is a link to the US tests carried out in the Isigny are of Normandy/France:
View: https://www.scribd.com/document/483711762/U-S-Army-Firing-Tests-conducted-August-1944-by-12th-U-S-Army-Group-at-Isigny-France# I know it and the UK report have been available free for download online at various sites in the past. IIRC it mentions the armour type used on the Panther glacis as face hardened.

The report at the bottom of this post is on the effectiveness of the US 76mm tank gun in WWII and talks about the problems encountered with the Panther (as well as having a bunch of other interesting info). It was published in 2018 and has additional information not available in 1945.

4. The drivers vertical plate I refer to is the Tiger I's near vertical (10°? from vertical) armour plate in front of the driver.

5. I am fairly familiar with the different types of penetrators, and there design 'qualities'. As far as I am aware there was really only 1 major distinction between the Soviet AP/APBC and the parallel purpose rounds used by the other combatants.

This involves the nose shape of the mid- to late-war penetrators for the steel bodied AP/APBC projectiles. The Soviet army started the war with pointed AP penetrators similar in design to the other combatants, and for the most part they worked against the German armour in the early part of their war. But around about the end of 1942 and into 1943 the Soviet tank & AT gunners began to notice that their AP rounds were breaking up against the face hardened armour on the upgraded PzKw III & IV tanks, along with the Tiger I, and then the Panther. When the Soviet field & design engineers looked into the problem they noticed distinct trends in the projectile failures and successes. In nearly all cases where the standard pointed AP rounds struck the armour at angles where they would have penetrated homogeneous armour - the nose shattered. Usually there was little of the ogive section left, and many times the body had also broken. But there were instances where the projectiles managed to penetrate the face hardened armour plates, and in nearly all instances the penetrator noses had broken in a similar manner - ie the hardened curved ogive of the nose had failed and shattered, leaving an intact main body with hard outer layer on body cylinder of the projectile and with a lesser hardness stub protruding from the front center.

Now, this is going to sound a bit like I am saying the Soviets could not - or did not have the skill/knowledge to - design a sophisticated capped AP projectile, but this is not what I am saying. Instead, IMO this is a very good sample of a combination of field engineering and design/manufacturing engineers and personnel coming up with a practical solution to a problem.

When the US, UK, German, Italian, and Japanese, designed their projectiles for use against face hardened armour they used fairly sophisticated penetrating caps, that had to be controlled in hardness to about the same degree as the main bodies of the penetrators - though the caps were usually of lower hardness. These caps also had to be attached in a reliably performing manner, which was somewhat problematic as to ease of manufacturing and consistency (at least in the early period of the war) and more expensive/time consuming to manufacture. Usually a ballistic cap was added to maintain good aerodynamics. The US 75mm M61 APC, for example, was actually an APCBC projectile. The Germans used APCBC almost exclusively on any guns above 50mm (IIRC the German 50mm had AP and APC only - no APCBC).

What the Soviet design and manufacturing personnel did was begin manufacturing their steel AP cores with a shape and hardness distribution similar to the shape and hardness distribution of the penetrators that had succeeded in penetrating the German armour. - ie shaped like the broken nose of the penetrator with the high hardness outer layer on the body cylinder and the less hardness stub that protruded from the center of the broken nose. The new nose shape and overall design of the penetrator entailed some undesirable trade-offs - ie a reduced effective penetration vs homogeneous armour in comparison to a pointed ogive, a reduced effective penetration vs more sophisticated APC projectiles like those used by the other combatants, and reduced performance at range due to the blunt aerodynamic of the nose. So the standard AP projectile for the Soviets became the APBC, with the ballistic cap making up for the poorer aerodynamics of the bare penetrator nose. The reduced penetration vs homogeneous armour was made up for by increasing the caliber of the guns (ie the Soviets went to the 85mm as the equivalent to the US 76mm and UK 17pdr, with their 100mm being the ~equivalent to the US 90mm). The increase in size also made up for the reduced performance vs face hardened armour. This design change also allowed quicker and easier production, with less need for sometimes scarce materials, while eliminating the problems with finicky hardening of the nose encountered by most nations attempting similar levels of performance.

IMO this is a classic example of field engineering effects on a responsive design and manufacturing community.

 

[tomo pauk]

Now, obviously, I don't have access to the original document, and maybe there's more to this than what I can see, but my immediate suspicion is that these aren't actually valid examples of the speed range of a production Spitfire Mk. V, and if they were being cited as such, were the numbers being misinterpreted...?

I have no problem with the idea that British documents of this sort might be as unreliable as anyone else's, though in this case, that would mean it's underreporting the performance of the Spitfire Mk. V...

I think that both of us made their respective points, thus I have nothing to add here (ie. to the topic of "Spit V vs. Fw 190A in 1941-42"). Readers of this discussion are, obviously, free to make their conclusions.