Kurfürst

Both pumps on? Maybe fuel pump capacity is modelled with one pump only...?

Some of the G-10 produced by WNF also seem to have been fitted with aileron Flettner tabs, as some of the previous WNF G-6s.

I meant its possible to slightly drop the flaps at very high speed on the 109s - which will increase drag and lift, allowing for tighter turns -and was used as such by some pilots and appears to have been intended for such use: a number of Bf 109E spec sheets and reports give the radius of turn for both normal condition and with flaps for example. AFAIK the Spit had such design goal for the flaps, i.e. strictly for landing, as it had only two positions: up and fully down.

Brilliant shots, thanks for posting! :)

It seems strange if the 109 could not deploy combat flaps at 400 mph as well, since the real one could, albeit I am sure it took some effort at such high speeds. Thanks for bringing this up and your other tactical findings! Its a very useful guide! :)

Interesting, I suspect with the gun ports open (i.e. not covered) there could be considerable turbulance over the wings and the ailerons. They are in fact quite considerable in size and located on the upper part of the leading edge, rather than in the centre. Here's a picture of a Mark V, showing the gun ports and the large cannon stubs to good advantage.

I respect that you are not much into researching it further, I was hoping that since you showed interest in the discussion, perhaps we could have learned more or unearth evidence so far unknown. As for the the 642 figure, it comes from a book I believe not a primary source, but anyway it works out to 398 mph, still a bit short of the the official figures and does not change much. As for the 405 mph figure, that I believe comes from JF 275, "trials with Super trop air intake 6-2-43", no further details known except it was at full weight by the manufacturer. Yes I agree it would be worth looking at, but IIRC it does not change much, given I have been concentrating on the actual top speeds by aircraft in serial production standard. Air intake factor can of course have effect on the FTH, but that's normal production variation - even on 109G tests I have seen it varies considerably, between 6100 and 7100 m, the mid value being in the order of 6600-6700m. Have you perhaps seen a similar mass test/scatter of production aircraft, such as this one performed by ERLA produced 109G? http://kurfurst.org/Performance_tests/109G_Erlatrials/Erla109G_13speedrun_scatter_web.jpg

Well, the report written by the professionals at Boscombe Down disagrees with your assessment and states that it was a standard, regular Spitfire IX. Here is how they write of JL 165: Summary Performance trials and a brief assessment of handling characteristics have been completed on a standard Spitfire IX with Merlin 66 engine, adjusted for maximum boost of +25 lb/sq.inch. and . Condition of aircraft relevant to tests. 2.1. General. The aircraft was a normal Spitfire F.Mk.IX. The following were the chief external features:- Two 20 mm. Hispano guns with sealed muzzles. Two 20 mm. gun stubs ith hemispherical fairings. Four .303" Browning guns, ports sealed. Ejection chutes sealed. Internal bullet-proof windscreen. Circular rear view mirror, with hemispherical fairing. Multi-ejector exhaust manifolds. Aerial mast. New tropical pattern air intake without gauze, but blanking plate installed. No ice guard fitted in air intake. Its worth noting that JL 165 already incorporated the latest improvements to the Mark IX line, such as circular rear view mirror, multi-ejector exhaust manifolds and New tropical pattern air intake without gauze. In other words it was the pinnacle of Spitfire Mark IX development, and developing a very impressive 389 mph, certainly very competitive with the contemporary Me 109G-6. But as you said by 1944, when it was introduced in numbers, the Mark IX was a bit long in the tooth.

Not a production Spitfire - BS 543 was a prototype for the IX. LF, with an experimental air screw and with the fuel mixture being set to far too rich (see subsequent correcting BS 310/M70 report), resulting in increased FTH and low/medium altitude performance, and much decreased high altitude performance. Hence the odd drop in performance in service ceiling. ;) ... which was never put into serial production on - the Mk IX. MA 648 was an experimental aircraft and not much else. Of course - JL 165 was a serial production aircraft in a serial production condition and representative of the Spitfires in service. The others were not, with the possible exception of BS 310. "the average of four Spitfires with Merlin 66s" you mention was the average of the two experimental test beds/prototypes mentioned above, BS 543 and MA 648, neither of which was representative of serial production Spitfires; the third was JL 165 itself; the fourth was the BS 310 test bed, which we do not know at all the test conditions at all. Ahh... Another serial production Spitfire test that needs to be dismissed because of alleged 'mistakes' (BTW the figures I posted are the corrected values) and instead experimental aircraft should be looked at as representative examples... ;) Sure its reliable, after all its a brand new Spitfire VIII, freshly delivered to the RAAF in good condition and noted to be in superior finish to all previous Spitfires the RAAF received; we all know the Mark VIII were aerodynamically superior to the Mk IXs: they had an all-flush riveting and a retractable tail wheel; furthermore this example had extended wingtips, which according to RAF reports increased speed at high altitudes compared to the normal one, because it actually lowered drag at higher flying AoA in the thin air. Speculation... Actually, the Russians managed to measure very good results for the Me 109G-2 they tested, which even slightly exceeded the Germans nominal specs for the aircraft (666 kph :evil: or 413 mph). BTW I find it interesting that the same institute under the same testing standards in the USSR measured 413 mph on a Me 109G and 390 in the Spitfire IX L.F. The Spitfire IXs they received were also brand new ones, they went straight to the USSR, as opposed to the handful of worn Mark Vs. Instead of the snide remarks, could you please provide these allegedly existing tests of production standard Spit Mark IX L.F., that you have claimed to show an average 404 mph..? And if you can't, maybe there is not much point in further arguing and we can agree that you believe that the speeds measured on two never-to-be-put-into-production prototypes are representative for the serial production Spitfires performance, and the speeds measured on serial production ones isn't...

Well if you want to do some hairsplitting the mathematical avarage (instead of the quick and dirty roundabout numbers) of all the known tested serial production Spitfires with Merlin 66 in serial production standard, i.e.: Testbed BS 310, Mk IX LF / M66 testbed, briefly tested in March 1943 resulting 404 mph. Testing Conditions unknown, but apparantly this was selected as the nominal spec. Serial production JL 165, Mk IX LF / M66 tested in a lightly loaded condition by R-R in October 1943, resulting 397 mph. Serial production JL 165, Mk IX LF / M66 tested in a fully loaded condition by R-R in February 1944, resulting 389 mph. Serial production JL 934, Mk VIII LF / M66 (extended wingtips and "virtually a new one") tested in a fully loaded condition by RAAF in April 1944, resulting 391 mph. Serial production from MJ/ML/MK *** series exported to USSR, Mk IX LF / M66 (cut wingtips), tested in a fully loaded condition by NII VVS in 1944, resulting 390 mph. is 394,2 mph, which is the avarage measured on production Spitfires with Merlin 66. This fells some 10 mph short of the nominal 404 mph, which is not so bad. Some fell a few mph below, but testing teams weren't completely stupid to reject an aircraft which fell one or two mph below to the lower limit. I know at least that BAL would make such exceptions within reasonable limits - the nominal spec of the late-war Me 262 for example was 870 kph. This came as an avarage of 125 tested production samples, so the avarage aircraft did fully comply with this spec, even in 1944/45. There were a number lower and higher performaning aircraft of course, but the minimum spec for accaptance was 830 km/h, which works out to something like 5% tolerance. In practice they would accept the ones doing 'only' 825 for practical reasons. And if an aircraft wouldn't meet specs it would be normally given back to the manufacturer to fix it. No, its your post on a forum, a speculation of what Supermarine's/CB's legal obligations might have been. A legal obligation OTOH would be a contract between His Majesty's Government and CB and/or Supermarine, detailing the conditions of acceptance and allowed variation from the contracted performance (which I assume was 404 mph) of the product. If you could produce this paper, this would be helpful to establish the allowed variations in performance. So lets see your figures for serial production Spitfires with Merlin 66, in production standard. No testbeds with experimental propellers or experimental injection carburrators that never saw service. Of course if you still can't provide that, there is not much point in further discussing speculations and we will have to agree to disagree. Until then, there is this fact of 390 mph being measured as top speed (394.4 mph for the sake of hairsplitting, and if we allow for the undocumented BS 310...) on avarage for the known production Spitfires w. Merlin 66.

No, its the practice vs the theory. In theory, the Mk. IX did about 405 mph. In practice, did around 390. What 'facts'? You have posted none.. Or ignore ALL the serial production test results and lets only concentrate or prototypes and experimental testbeds... Right?

Lots of speculation and some snide comments but none of the trials you claimed to have existed could be posted, Friedrich. So I guess it is settled, 390 mph on avarage for serial production Merlin 66 Spitfires then. Its reassuring that Friedrich now admits that the build quality issues he claimed to have been remedied weren't solved at all. Its also worth noting that the USSR received - and tested - Mk. IX LFs that were built at the end of 1943. They still got 390ish results. I wonder if these build quality issues are related to that Castle Bromwhich being a quantity before quality enterprise for mass production. It may be interesting that Rechlin also measured 625 km/h for the M61 model, some 30 km/h slower than the RAF's nominal figures.. ;)

As I understand the German page posted by Crumpp, the 670 number is not valid and research has showed that 1805 D-9s were actually produced. Thats roughly the number of the Spit XIV and Tempest production combined... Which I dare to say is a significant amount, given the small timespan of production, i.e. less then a year. In any case, everyone knows I think that the D-9 was a substantial and common model seen late in the war, so whats the point of all these arguements..?

Well lets see. Testbed BS 310, Mk IX LF / M66 testbed, briefly tested in March 1943 resulting 404 mph. Testing Conditions unknown, but apparantly this was selected as the nominal spec. Serial production JL 165, Mk IX LF / M66 tested in a lightly loaded condition by R-R in October 1943, resulting 397 mph. Serial production JL 165, Mk IX LF / M66 tested in a fully loaded condition by R-R in February 1944, resulting 389 mph. Serial production JL 934, Mk VIII LF / M66 (extended wingtips and "virtually a new one") tested in a fully loaded condition by RAAF in April 1944, resulting 391 mph. Serial production from MJ/ML/MK *** series exported to USSR, Mk IX LF / M66 (cut wingtips), tested in a fully loaded condition by NII VVS in 1944, resulting 390 mph. So while I agree with you that it is very likely that most Spitfires could satisfy the production tolerance of 3% for the nominal 404 mph top speed (that is, a minimum of 392 mph), there is a strong indication that they were typically sat at the lower end of the tolerance, ie. around 390 mph.

Scroll back a couple of pages in this thread, as I already have - we will now see what other tests you or Friedrich may be aware of. Did they ever mass test the production speed of serial production Spitfires, I wonder.

Meh. Ju 188 all the way! :)

An interesting claim and it also runs contrary to what I have seen in Merlin 66 tested aircraft. Would you kindly share with us all these alleged "testings" that were supposed avarage out to exactly 404 mph? Except for the fact that none of the Merlin 66 powered serial production Merlin 66 Spit testing I have seen shows that they could even reach even 400 mph, so it was either a build quality issue or there was some magic coincidence in that each and all the tested planes must have been 'lemons'... So lets just see the hard evidence you can surely present: test results of serial production Merlin 66 aircraft and evidence of when and to what extent the planned improvements were realized in serial production.

T'is very interesting and all, but is there *any* test of a serial production Spitfire Mk. IX L.F. would indicate that the common type could reach even 400 mph..? Plans and attempts were plentiful I am sure of that - but in the end they either did not realize or simply failed to remediate the problems with aerodynamic quality. By contrast the late war performance trials of 109G and K I have seen show that they reliably reached and sometimes even exceeded their 'paper' specifications.

The only problem is that no test seem to exist for serial production aircraft that would even reach 404 mph, they are rather more in the 390-395 region - BS 310 may be stretching it a bit since we do not know the testing conditions. But that's OK, I suppose the RAF had its reasons to accept BS 310's 404 as a sort of nominal spec, from which serial production a/c may differ up or down by 3% due to production tolerance.

Reported to the Devs about a week ago, along with the relevant manual Bellanato posted, so they know about it and hopefully will be fixed... anyway I was a bit unsure if it made to serial production, so thanks for the confirming pictures, 605! :)

Is it possible perhaps that for the sake of testing, they took a stock Mark IX with a Merlin 66 engine with a Bendix carb and set to the standard +18 lbs, and then modified it with a SU injection unit / modified boost regulator allowing +25 lbs..? Like Messerschmitt AG did when they took a stock 109G-1, the serial no. 14 026, and then re-fitted it with a taller tail unit, replaced one of the radiators with a different unit, fitted a fixed tail wheel, a radiator position indicator and swapped the stock DB 605A for a 601E of the 109F? After all, that's the very definition of a testbed. Or when DB AG took a stock serial production Mark V, stripped the Merlin out of it and bolted on a 605A under the hood from a Me 110...? Or it was production standard at the time, and there existed Spitfire Vs with DB 605As in serial production, and can't have both in existence?

Wasn't Rolls Royce the manufacturer of the Merlin 66? I am sorry but you need to re-read my post, as I did not claim any such thing. What I wrote and meant was that the Supermarine Spitfire Mark IX. Low-Fighter, serial no. JL 165 was a serial production machine, used for testing by the manufacturer of the aircraft's engine, that is, the Rolls Royce aero engine company.

There is nothing unusual in serial production machines being used for testing by the manufacturer, often repeatedly. Its saves money for the company. A fighter aircraft wasn't cheap back then, nor it is today.

So in other words, if weren't for MA 648 being an experimental testbed with a non-representative injection pump, it would be representative of serial production machine, aside from that it isn't. Looking at the performance figures obtained in testing with the testbeds and experimental machines, it becomes obvious why experimental configurations are preferred at times for being representative - they performed better than the actual aircraft delivered to units. ;) BS.543 prototype w. experimental propeller and overly rich mixture - 407 mph at 22100 ft MA.648 testbed w. experimental SU injection pump - 411 mph at 21100 ft BS.310 serial production aircraft - 404 mph at 19500 ft JL.165 serial production machine - 388 mph at 19300 ft. Its worth noting that the testbeds due to their configuration achieved The official specs for the Mark IX.L.F. was an 404 mph, probably based on the BS 310 testing results, with a tolerance of 3 %. None of the serial Mark IX LF tests apart from the BS 310 trials referred to in other docs (w/o the testing details) I have seen ever managed to reach these official specs - all other testing of actual serial production machines yielded top speed results in the 390 - 400 mph range, i.e. trials by R-R, RAAF, and VVS.

Which is probably why this experimental setup on the MA 648 testbed was not bothered to proceed with and be put into serial production on existing models, hence in my opinion its largely irrelevant to the subject matter.