DCS: Spitfire Mk LF IXc Discussion

[MiloMorai]

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.

 

453S Missing nr Arnhem 27-9-44 operational Spitfire

 

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.

Transfered to Air Service Training 3-6-44

 

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.

 

JL serials ended with JL395 extended wing tips, so would be slower

 

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.

 

using Soviet fuel???

 

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.

 

BS543 Mk IX LF / M66 407mph

403 Sqdn. 9-6-43; 611 Sqdn. 10-6-43; 485 Sqdn. 6-7-43. Failed to return from operations 22-8-43.

[Friedrich-4B]

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.

 

There's also BS534 which reached 407 mph at 22,000 ft

 

http://www.spitfireperformance.com/bs543.html

 

not forgetting that Kurfurst chose to use a Mk VIII test, but excluded MA648 (411 mph), supposedly because of the injection pump which, according to the report increased the full throttle height and the top speed slightly, but nothing much else: the same report shows that JL165's performance was well below the average of four Spitfires with Merlin 66s that were tested (388 mph vs 411, 407 and 404 mph)

 

http://www.spitfireperformance.com/ma648.html

 

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.

 

JL.165 was manufactured at Castle Bromwich as a Spitfire V (Merlin 45) and delivered on March 27, 1943. It was subsequently converted to a LFIX (Merlin 66) at Rolls Royce, Hucknall; it definitely wasn't a "serial production" L.F Mk IX. It was built at about the time there were some build quality issues being noted; here is the relevant post:

 

http://forums.eagle.ru/showpost.php?p=2270426&postcount=339

 

The report on JL165 also noted the following:

 

4.41. An increase of about 950 ft/min in rate of climb and about 30 mph in all-out level speed is achieved by the increase of boost from +18 lb/sq.in. to +25 lb/sq.in.

4.42. The comparison of this estimated performance with that obtained on Spitfire F.Mk.IX BS.543 with Merlin 66, shows rather lower figures for JL.165, particularly in all-out level speed.

 

the R-R report on JL165 (pdf file attached) notes that

A further point of note is that the full throttle height at +18lbs of boost which is somewhat lower than has been previously been obtained with Merlin 66s....It would seem therefore that the full throttle height of this engine is low.

 

In fact the F.S full throttle heights were 13,800 ft and 14,400 ft vs a normal full throttle height of about 19-21,000 ft

 

http://www.spitfireperformance.com/jl165.html

 

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.

 

Yes, the tests were very enlightening, unfortunately because there were some fundamental mistakes being made, as noted on the first page of the report:

 

 

Things got better, because the top speed was reached above the full throttle limits, creating some confusion over the results: "Checks on another Spitfire will be made when available."

 

 

Nor was the equipment used to conduct the test specified, except that the climb tests used a stopwatch and the altimeter...

 

 

So, the RAAF tests can be considered very reliable :smilewink: and indicative of the performance to be expected by an L.F Mk IX with normal wingtips and weighing some 200+ lbs less than a Mk VIII ;)

 

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.

 

Test conditions unknown; it is also known that the Russians often underestimated the performance of foreign aircraft.

 

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.

 

Well, that's Kurfurst's opinion; no doubt the ED team will have better info available to them.

 

It should be noted that the RAF recognised that the Mk IX was nearing obsolescence as a pure fighter over Europe, which is why it became a low-level tactical fighter-bomber - most test reports after the preliminary speed/climb reports with testbeds concerned the Spitfire L.F IX's handling with various bombloads etc: from Morgan & Shacklady:

 

Edited December 30, 2014 by Friedrich-4/B
Add R-R report on JL165

[Kurfürst]

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.. ;)

Edited December 29, 2014 by Kurfürst

[JtD]

So I guess it is settled, 390 mph on avarage for serial production Merlin 66 Spitfires then.

Impossible, since it doesn't meet the minimum requirements. It actually goes against the limited facts available.

 

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.. ;)

Yeah, and lets take RAF tests to accurately describe Fw and Bf performance, after all, the Russian tests back them up.

[MiloMorai]

I seem to recall someone commenting on the British testing of captured German a/c saying the a/c had been repaired after damage, wrong fuel, and other excuses so would not be performing as they should.

[Kurfürst]

Impossible, since it doesn't meet the minimum requirements.

 

No, its the practice vs the theory. In theory, the Mk. IX did about 405 mph. In practice, did around 390.

 

It actually goes against the limited facts available.

 

What 'facts'? You have posted none..

 

Yeah, and lets take RAF tests to accurately describe Fw and Bf performance, after all, the Russian tests back them up.

 

Or ignore ALL the serial production test results and lets only concentrate or prototypes and experimental testbeds... Right?

[Friedrich-4B]

Lots of speculation and some snide comments but none of the trials you claimed to have existed could be posted, Friedrich.

 

Correction: None of the trials listed by Morgan and Shacklady could be posted.

 

Its reassuring that Friedrich now admits that the build quality issues he claimed to have been remedied weren't solved at all.

 

A completely ridiculous claim; the actual statement was:

 

Attached is the full RAE report on the finish and equipment of the Spitfire VC and IX. Coinciding with the RAE report, steps were already being taken to improve the finish of Spitfires on the production line; it was also agreed that improved servicing standards on squadrons would be promulgated:

 

Followed by:

JL165 was manufactured at Castle Bromwich as a Spitfire V (Merlin 45) and delivered on March 27, 1943. It was subsequently converted to a LFIX (Merlin 66) at Rolls Royce, Hucknall; it definitely wasn't a "serial production" L.F Mk IX. It was built at about the time there were some build quality issues being noted...

http://forums.eagle.ru/showpost.php?p=2275726&postcount=353

 

I wonder if these build quality issues are related to that Castle Bromwhich being a quantity before quality enterprise for mass production.

 

I wonder if the build quality problems being experienced by MTT Regensburg had anything to do with using PoWs, forced foreign labour and slave (concentration camp) workers?

 

Edited December 30, 2014 by Friedrich-4/B
Small o

[JtD]

No, its the practice vs the theory. In theory, the Mk. IX did about 405 mph. In practice, did around 390.

Which would lead to the rejection of most Mk.IX built, since contract obligations were not met. Well, maybe they would have been taken into service, if provided for free.

 

What 'facts'? You have posted none..

404mph +/- 3%. Legal obligation.

 

Or ignore ALL the serial production test results and lets only concentrate or prototypes and experimental testbeds... Right?

You gave a single VVS test, some estimated performance of a testbed and a Mk. VIII test. On the bottom line, one figure. I gave another one, same source. Reminder: 642 km/h / 399 mph. I don't even see how that averages out to 390, but even if it did, I wouldn't be so stupid to accept broad generalisation based on two figures.

[Kurfürst]

Which would lead to the rejection of most Mk.IX built, since contract obligations were not met. Well, maybe they would have been taken into service, if provided for free.

 

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.

 

404mph +/- 3%. Legal obligation.

 

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.

 

You gave a single VVS test, some estimated performance of a testbed and a Mk. VIII test. On the bottom line, one figure. I gave another one, same source. Reminder: 642 km/h / 399 mph. I don't even see how that averages out to 390, but even if it did, I wouldn't be so stupid to accept broad generalisation based on two figures.

 

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.

[Kurfürst]

There's also BS534 which reached 407 mph at 22,000 ft

 

http://www.spitfireperformance.com/bs543.html

 

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. ;)

 

not forgetting that Kurfurst chose to use a Mk VIII test, but excluded MA648 (411 mph), supposedly because of the injection pump which, according to the report increased the full throttle height and the top speed slightly,

 

... which was never put into serial production on - the Mk IX. MA 648 was an experimental aircraft and not much else.

 

the same report shows that JL165's performance was well below the average of four Spitfires with Merlin 66s that were tested (388 mph vs 411, 407 and 404 mph)

 

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.

 

Yes, the tests were very enlightening, unfortunately because there were some fundamental mistakes being made, as noted on the first page of the report:

 

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... ;)

 

So, the RAAF tests can be considered very reliable :smilewink: and indicative of the performance to be expected by an L.F Mk IX with normal wingtips and weighing some 200+ lbs less than a Mk VIII ;)

 

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.

 

Test conditions unknown; it is also known that the Russians often underestimated the performance of foreign aircraft.

 

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.

 

Well, that's Kurfurst's opinion; no doubt the ED team will have better info available to them.

 

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...

[Random]

Guys enough of the broken record. I've said it before just let ED do their job. Has anyone noticed a 10mph or greater error in any of the ww2 modules up until now?

 

Kurfurst you really need to stop worrying about thd Mk.IX sissyfire the Mk.XIV is bigger badder and faster ;)

 

Edit: didn't mean to sound like a moderator there but it both sides arguments are predictable...

[JtD]

Kurfürst, I've already said that I don't care enough about the issue to do actual research. I go with the numbers I know, which happen to be the ones you keep posting plus a figure of 642 km/h you keep ignoring, and if you were to include the VIII, a figure of 405 mph. But all that's there does not sufficiently support your point of view.

 

Anyway - have you ever considered to look at speeds not at full throttle altitude, say 5000 feet? With the biggest effect of intake, injection and supercharger differences eliminated, this would give a much better view at the picture then comparing speeds at 5500m with speeds at 6500m.

[Kurfürst]

:doh:

 

Nope: JL165 was a conversion that didn't reach operational service

 

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.

[Anatoli-Kagari9]

I want a C182 RG! Now! Ah! and an AS-K21

[Kurfürst]

Kurfürst, I've already said that I don't care enough about the issue to do actual research. I go with the numbers I know, which happen to be the ones you keep posting plus a figure of 642 km/h you keep ignoring, and if you were to include the VIII, a figure of 405 mph. But all that's there does not sufficiently support your point of view.

 

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.

 

Anyway - have you ever considered to look at speeds not at full throttle altitude, say 5000 feet? With the biggest effect of intake, injection and supercharger differences eliminated, this would give a much better view at the picture then comparing speeds at 5500m with speeds at 6500m.

 

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

[Friedrich-4B]

Guys enough of the broken record. I've said it before just let ED do their job. Has anyone noticed a 10mph or greater error in any of the ww2 modules up until now?

 

Kurfurst you really need to stop worrying about thd Mk.IX sissyfire the Mk.XIV is bigger badder and faster ;)

 

Too right; the weather in this part of the world is fantastic and I can't be bothered wasting any more time chasing my tail over this. I have no doubts that DCS will have more reliable information than what's currently available on the internet.

 

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.

 

Thanks. You see? It isn't so hard admitting that 398 mph is short of the official figures and that the guesstimate of 390 mph for a Spitfire L.F Mk. IX is way too low, based as it is on a skewed set of figures. Well done!

Edited December 30, 2014 by Friedrich-4/B

[Solty]

Ahem. May I interupt this vivid conversation? OK. I have a question...

 

When will we see some screenshots of the Spitfire MkIX and get any information what kind of MkIX will we get?

[NeilWillis]

I suspect Solty that we'll next see stuff on the Mk IX when they release the pre-purchase information.

 

Hopefully, it'll be announced soon.

[Friedrich-4B]

Here are a couple of photos of Spitfire L.F Mk XVIEs, with clipped wings, of 421(Canadian) Sqn. based in Belgium in 1945:Note the unusual camouflage pattern on SM309 AU+H.

 

 

While not Spitfire L.F Mk IXCs, 421 Sqn were equipped with Spitfire IX/XVIs right through D-Day to VE day. Many of them had the Indian chief insignia on the port lower cowling panel:

 

[nick10]

Would be nice to an idea of how the spit is coming

[Kurfürst]

Phrasing. :p

 

Here's a picture of a properly modeled Spit in the meantime. :D

[Crumpp]

Here's a picture of a properly modeled Spit in the meantime

 

There is a Spitfire in that picture? Where??

 

:huh:

[MiloMorai]

There is a Spitfire in that picture? Where??

 

:huh:

 

There is 2 Spitfires in that picture.:thumbup:

[TwoLate]

I really love the way the background sky looks. Great Pic

[Crumpp]

I really love the way the background sky looks. Great Pic

 

:megalol:

 

You must be Pat.....