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!