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Notes for

"Spitfire Mk XIV versus Me 109 G/K A Performance Comparison"

article at the 'Spitfire Performance Testing' created by Mike Williams

The original can be viewed here.



False behaviour is no other than an imitation of truth.


- Iustinianus


The following article is intended to correct the various errors, flaws presented in a series of articles on the relative performance of the Messerschmitt Bf 109 and Supermarine Spitfire by Mike Williams. Altough a constructive discussion was attempted with the author(s), pointing out the various flaws that are misleading in these texts - especially for those who are not familiar with the subject - but these effort proved to be a futile.

This finally convinced me that some of these 'errors' are  intended to mislead the readers, and convince them of 'facts' that the author himself sees 'proper' - especially when taking into account the site and it`s author`s record. Whereas I think the expression of different opinions is something to be encouraged, as it allows us all to learn new ways and see things from new perspectives, I tend to believe that propagating an agenda in a so much false version, created with lowly tricks such as a very selective use of qoutes, information and documents, mislabelling of the information and hand-picking which data is to be presented and which is to be hidden away, is extremely harmful for those who are seeking to learn about history in general, in our case, aviation history.


Therefore I have decided to put this critic together, pointing to the facts the Mike Williams was honestly unaware of, as well as those that he was dishonestly hiding, manipulating or ignoring. It will be followed by others, referreing to his other articles, epecially if there will be no change in the attitude shown.



Notes regarding fighter types and their performance in the first half of 1944 :


"The Spitfire XIV entered service with No 610 squadron in January 1944, followed shortly thereafter by Nos. 91 and 322 in March. "


Unit First received XIVs First loss known Maximum number of aircraft*
No 610 Squadron January 1944 14th May 1944 12 (plus 8 reserves)
No 91 Squadron March 1944 29th April 1944 36 (plus 24 reserves)
No 322 Squadron 3th May 1944
No 130 Squadron August 1944 N/A 72 (plus 48 in reserve)
No 350 Squadron N/A
No 402 Squadron N/A


Indeed - at least on paper. However loss reports does not indicated the type had see much - if any - action until the last days of April 1944.

It would appear that the Squadrons were first issued with a number of Mk. XIV aircraft in January, however, delays with production meant  deliveries were very slow - No 610 Squadron`s Operational Record Book`s entry on 31st March 1944 states that the conversion process was not completed until April 1944 : "The Squadron is now fully equipped with Spitfire Mark 14 aircraft."


* Hypothesizing the unit being 100% on-strenght.

 This proved to be rare under continous combat operations.


Considering that a RAF fighter Squadron consisted of only 12 airplanes to be used on operations, with additional 8 reserves present, the fact that it took 3 months to deliver 20 planes to equip a single squadron gives some idea on the production rate of the Mk XIVs. The time needed for the pilots to get used to them also took some time and delayed the combat debout of the Spitfire XIV - as evidenced by the dates of their first losses, as for any combat plane that is regularly used on combat sorties, losses are inevitable. If for no other reason, accidents. The lack of records of such losses occuring points to that the unit - and the Mk XIV - did not reach operational status until spring of 1944, at least there`s no evidence to the contrary. Curiously enough, at the time in January to March 1944, when the single XIV squadron was slowly being equipped, there were still three Hurricane squadrons operating from Britian. We can say, that, at the time of it`s introduction, the - by then completely obsolate - Hurricane was three times as 'representative' of  the RAF`s fighter forces, than the Spitfire Mk XIV...


"At about the time of the Spitfire XIV's entry into service its Me 109 counterpart was the Me 109 G-6 with the DB-605 A cleared for 1.42 ata take-off and emergency."

Along with others. Whereas the G-6 was the main type of the 109 in early 1944, the G-5/AS and G-6 /AS types were appearaning into service as well, and by the time the MkXIVs suffered their first losses, they were begun to utilize MW-50 injection, along with the increased maximum boost of 1.7ata it provided :

"[...]In mid-April Barran joined us, after leaving the hospital.

Brand new fighters have arrived, straight off from the factories. These are now both equipped with (high altitude) supercharged engines and the new MW booster. I had personally participated testing the latter. Thanks to this new invention, in case of emergency, we can now force the engine to 40% higher output for a duration ofseveral minutes.[...]"


- Heinz Knoke : I flew for the Fuhrer.

                         Entry of 28th April 1944.

The resulting 109G types, equipped with DB 605 ASM, were considerably faster than RAF`s Spitfire L.F. Mk. IX type fighters, still running at +18 lbs/sq.inch boost, especially at higher altitudes. The introduction of  the use of 150 grade fuel in the summer for the Merlin 66 did not changed the picture much - it only allowed to increase to +25 lbs/sq.inch boost below the the relatively low rated altitutude of the Merlin 66 - 16 250 ft. The supercharger remained unchanged, therefore the altitude performance, still the same as in 1942, left much to be desired by 1944 standards. Perhaps the fact that these late, high altitude 109s could max.continous cruise speed at those altitudes was as fast or faster than the all-out level speed of the Spitfire Mk IXs tells more on that subject that anything, taken from the GL/C- E2 Flugzeug-Entwicklungs-Blatt :
the G-5/-6/-14/AS could maintain 620 kph at 8.4km in cruise (385mph at 27 550 ft ), the G-10 628kph (390mph), the K-4 645 kph (400mph) at the same alttiude. Naturally at full power much higher speeds could be reached at this altitude - 700 kph/435mph in case of the K-4. Datasets for G-10 and K-4 are with the early production, and weaker DB 605 DM engine. Even with this they compare favourably at the same altitude to the all-out level speed of the Spitfire L.F. Mk IX,
631 kph
or 392 mph at 8.4km / 27550 ft.

Maximum continous cruise speed of the Spitfire F. Mk. XIV was 380 mph 25 000 ft (611 kph at 7620m), given by AIR 15/741.

The comparison of the performance of these 109G types to the MkXIV is interesting, but highly academic : even half a year after their official introduction, the Mk XIVs presented only a fraction of the RAF`s fighter forces - dominated by the Mk IXs at that time - with no more than 6 Squadrons using them, compared to 34 of the Mk IX Squadrons immidiately supporting D-Day, and another 22 of the IX Squadrons being responsible for the defence of the British Isles(SS4), organized into the ADGB (Air Defence Great Britain) - a total of 56 of the Mk IX Squadrons around compared toa mere 6 using the Mk XIV... this situation did not change even until V-E day, as no more but one XIV Squadrons were created in the meantime.


"The DB-605 AS, with improved altitude performance, came into service during the spring of 1944."

"MW-50 was introduced that summer in the Me 109 G-6/R2 and Me 109 G-14 enabling improved low altitude performance. "

The first AS engined aircraft were produced from December 1943, at the same period the production of the MkXIV Spitfires commenced.

Altogether 686 G-6/AS aircraft were built or converted from existing airfames, along with 76 G-5/AS, 16 G-5/R2/AS, 68 G-5/R6/AS, the only difference being G-5s having pressurized cocpits for the pilot`s comfort at high altitudes.

From spring of 1944 - and not during the summer as Williams suggests - MW 50 injection appeared on the Bf 109s,  resulting two 'new' engines, the DB 605 AM with 1800 PS and a rated altitude of 4km / 13 125ft, and the DB 605 ASM with 1800 PS and a rated altitude of 6.5km / 21 000 ft. Both were essentially modified DB 605 A and AS engines (AS itself was based on the DB 605A-1, with it`s supercharger replaced by a larger one taken from the DB 603 G engine) equipped with MW-50 boost, boosting low altitude output up to the rated altitude, above which the MW injection ceased and performance was the same. These engines were built into both G-5/AS and G-6/AS aircraft, and was noted by Heinz Knoke`s  war diary above. In addition, Olivier Lefebvre noted about conversion kits for the G-6/U2 subtype, which featered a nitrous-oxide booster (GM-1) tank, that could be converted to use MW booster with little difficulty  :

"250 conversion kit were issued early spring 1944 for the already produced /U2 aircraft and switch on the production lines from GM-1 to /U2 occured at that time as well. The G-6/U2 convertion was standardized over the next few months, with replacement of the heavy tank with a thin aluminium one and some modifications in the MW-50 piping. While those aircraft were still produced as G-6/U2 the name switched to G-14 during summer 1944, the late G-6/U2 being identical to G-14."

From July 1944 the production of these improved G-6s was standardized, re-designated as G-14 (with medium altitude 1800 PS DB 605 AM) and G-14/AS (with high altitude DB 605 ASM), but otherwise differed in little from those late production G-6s. Some 1830 G-14/AS aircraft were built, bringing the number of 605AS and ASM engined G-5s, G-6s and G-14s to ca. 2500 examples. The number of G-14s built in total is unknown, an estimated about 3-4000 examples, the exact number being difficult to tell because of the many converted/repaired airframes.


Some notes on Mike William`s graphs :


1st Graph :  Spitfire Mk XIV vs. Bf 109 G - Level Speed performance


The "G-14/U4 DB 605ASM" - as also noted by Mike Williams-  are with Gondelwaffen, 20mm gunpods attached to the wings. These weighted 215 kg loaded, hence the 3550 kg take off weight - as opposed to 3272 kg of the 'clean' G-14/AS (some of the weight difference is attributed to the /U4 subtype equipped with the 3cm MK 108 engine cannon). Though the gunpods effected climb rate most severely - by ca 2 m/sec or 400 ft/min - they also effected the maximum speed of the aircraft, especially at altitude, due to their increased drag.

According GL/C- E2 Flugzeug Entwicklungsblatt Bf 109 (J) as of 13th August 1944, the clean G-14/AS was reported with 560 kph / 348 mph speed at SL, and 680 kph at 7.5 km or 668kph/423 mph at 24 600 ft - as opposed to 550 kph/342mph at SL and 415mph at 24 600 ft on William`s graph. This is in good agreement on the effect of the gunpods noted by other sources such as Soviet flight tests and Mtt`s drag specsheets ('Zusammenstellung der Leistungseinflüsse verschiedener Anbauten'), which are noted to decrease level speeds by ca. -8 kph at SL, and -15 to 20 kph at rated altitude, somewhat more above that. The difference can also be noted in comparison to G-5/AS level speeds at Notleistungs at higher altitudes - a clean G-5/AS and G-14/AS should be identical at the higher altitudes, ca. 8200m and above, as the engine power output as well as the airframe were also identical.

This decrease of level speed is to be noted when judging the performance of the G-14/U4/AS in this graph, and should born in mind that a normal fighter version is ca. 15kph or 10 mph faster at all altitudes.

Similiar is the case with the  "Me 109 G-6 DB 605 A, Start-Notleistung, A1/27/58/44" graph, coming from the same sheet as the "Me 109 G-5 DB 605 AS, Start-Notleistung, A1/27/58/44" curve. The only condition noted for the G-6 w. DB 605A-1 is the weight (Gewicht), G=3350 kg. Normal take off weight of the G-6 was 3150 kg, therefore in this curve there`s some extra equipment carried. The amount of extra weight (+200kg) and speed loss compared (520kph is stated for SL) to the GL-C/E2 figures for G-6, 530kph at SL points to that again 20mm gunpods are included in the test, which came with - as noted - a loss of 8 kph at SL and weigted 215 kg, loaded with ammunition. Therefore this dataset is again comparing a heavily loaded anti-bomber setup of the Bf 109 to the Spitfires without any external stores. One things that is missing is the lenghty excuse from Williams about the need to take these figures 'with reserve', though they also come from the Messerschmitt Projektburo. It appears that the need for such notice was seen as unneccessary, when the figures presented for the Bf 109 under rather unfair conditions are low and thus satisfying for the agenda.


2nd Graph :  Spitfire Mk XIV vs. Bf 109 K - Level Speed performance

"The following charts reflect performance of the Spitfire XIV and Me 109 K from the introduction of the K in October 1944 through to VE day. The Spitfire XIV's performance was rather stable, new development going toward the Spitfire Mk 21, whereas efforts were taken to increase the output of the DB 605 D series in order to make the Me 109 K-4 more competitive. It is not known if the 109 data is from flight trials; certainly in some cases the date of the drawing argues against it. While the curves are simplistic, they should give some idea of potential, however, they should be treated with reserve."

Mr. Williams, is using the data stated in 'Leistungen 8-109 K4 und K-6 mit DB 605 ASCM/DCM. Oberammergau, den 11.12.44 and 1.19.45, prepeared by Messerschmitt AG, says "Bf 109 K the curves needed to be treated with reserve."

He has no such reservations about his own estimates on the Spitfire XIVs performance on +21 lbs, which are considerably higher than what was actually measured by R-R... The descriptive part of 'Leistungen 8-109 K4 und K-6' notes the following. He probably missed it, so here it is :

'Die angegabenen Leistungen werden mit gut gebauten Serienmachinen sicher erreicht.', or 'The above given performances are certainly going to be reached with well-built serial production machines.' No comment. Further it notes the performance curves contain no special threatment of the airframe, which would add +12 kph..

I`d say what`s needed to be treated with reserve is William`s interpretation of the primary sources. Especially, as they underwent serious changes compared the original, before appeared on the web, by mistake, or... such as :

'Me 109 K-4 DB 605 DM Start-Notleistung mit MW-50, 5.5.44.' : One small detail wasn`t noted,

and that is - the performance data refers to 3550 kg (see the case of the G-14 above), which points to gunpods, and all the performance loss associated with them - the normal takeoff weight of the K-4 was 3362 kg, according to the GL/C-E2 datasheets. I wonder how the Spit XIV would compare with a 500 lbs bomb to a clean 109 K though. It`d be a similiarly 'fair' comparison.


'Me 109 K-4 DB 605 DB/ASB Sondernotleistung with MW, productionprop' level speed curve by Williams, for some reason, don`t match the original curve of the Messerschmitt document, and state 365 mph at SL, which is wrong; by all likelyhood the home-made curves, present the 200 kg heavier
K-6 subtype`s performance (it`s located on the same paper) instead of the K-4 with DB powerplant at 1.8ata. With it`s extra wing armament (two MK 108s in the wings), the heavy figther K-6 was 5-10 kph slower than the K-4 - and besides most likely never saw service.. This explains why this curve also shows much lower altitude performance than the other 109K curves, as on the original. For K-4`s with DB engine, performance is given at 595 kph / 370 mph at SL in the original, the altitude perfromance above 7.5km is similiar to that of the DC engined variants.

The question arises, if this mistake has a connection with the results (366mph at SL) obtained by R-R in June 1944 on the Mk XIV Spitfire, running at the highest boost ever cleared for it in it`s operational service, +21 lbs/sq.inch on 150 octane fuel, compared to the lower boost pressure cleared for the 109 K, 1.8ata utilizing 87 octane fuel... Hopefully this mistake will be corrected soon.

'Me 109 K-4 DB 605 DC/ASC, takeoff emergency, at 1.8ata, productionprop' curves show the plane with DB 605 DC powerplant at 1.8ata; this curves has little relevance, as this chart is originally noted as 'o. MW' - without using MW-50, a conditions practically non-existant in real life. Perhaps it was nice to have low-valued 109K curve on the chart, too. ;)

'Me 109 K-4 DB 605 D, Sondernotleistung with MW, productionprop' - this refers to the DC powerplant, running at 1.98ata, but barely visible, thanks to Williams use of a light yellow dotted line on white background(!!!!). A classic one, congratulations, Mike!

Perhaps it has to do with the 15-30 mph level speed advantage displayed by the 109K-4 over the Mk XIV Spitfire, at all practical combat altitudes from Sea Level all the way up to 24 000 ft, even when compared to Mike`s own estimation/imagination of it`s +21 boost performance.


3rd Graph :  Spitfire Mk XIV vs. Bf 109 K - Climb performance


'Me 109 K-4 DB 605 D Start-Notleistung mit MW-50, 3.5.44.' - or how to belittle real values by picking a curve for an aircraft that is 200 kg heaver than the normal one. See to the left.

'Me 109 K-4 DB 605 DC/ASC, takeoff emergency, at PL=1.8ata, Ladedruck 1.8ata, productionprop'

and 'Me 109 K-4 DB 605 DC/ASC, takeoff emergency, at PL=1.8ata, Ladedruck 1.98ata, productionprop'curves show the plane with DB 605 DC powerplant at 1.8ata; at when the maximum boost of the engine is set to 1.8 and 1.98ata, but not using MW- this chart is originally noted as 'o. MW', condition practically non-existant in real life, but will show lower values as the power output is lower as well..

While the atypical DC curves at 1.8ata were picked is a mystery (or maybe not); there are also curves for 1.8ata when using the DB 605 DB powerplant, and these show higher performance, especially at altitude - the reason for this is that the 605 DB powerplants used lower octance fuel, and because of that MW 50 was injected at a wider altitude range. Because of the MW particles increased charge weight via cooling (and also the contained methanol was a fuel on it`s own), this injection resulted in a 4% increase of power even on the same boost - a sudden drop of speed is visible on both G-14/AS and K-4 curves above when the MW injection is ceased when boost drops above rated altitude ('MW Abschaltung', as noted on the graphs).

And then of course we have the performance of the K-4 at, horribile dictu, full power, 1.98ata. YES, naturally displayed with a light yellow, dotted line on white background. :D

"GL/C- E2 from 1.11.44 gives 360 mph at SL, 441 mph at 24,606 ft. with production 9-12159 propeller and would represent performance from introduction of the Me 109 K-4 in October 1944 to March 1945; and more than likely for most units, given little evidence to the contrary - to war's end. "

Again wrong on almost all accounts. It follows the usual practice of Williams articles, picking the lowest possible performance numbers for the 109 series, and then attempting to prove that these, and these alone are valid.

The mentioned GL/C- E2, Flugzeug-Entwicklungs-Blatt (Aircraft development datasheet) was published on 1st November 1944, but it clearly notes also the date to which  the given performance, weight data etc. refer to ('Stand vom'). In this case, the sheet refers to the conditions as of  13th August 1944, provided by the manufacturer - and just repeats the projected performance as of May 1944, for an aircraft that isn`t even service as yet.. The  power outputs given for the 'DB 605D' on the GL/C datasheets make clear the performance numbers relate to the DB 605 DM powerplant mounted only on the earliest production batches - and in on which`s output the projected performance was based on ! Noteworthy that the first known test flight of a pre-series 109 K-4, Werknummer 330 103 was made on the 11th August 1944.  

The 605 DM engine being a stopgap measure until production of the considerably more powerful DB and DC engines reach sufficient levels.

Olivier Lefebvre, 'a noted authority on the Bf 109', has also stated :

"Indeed there were two kind of engine fitted on the K-4, the DB605DM from which I believe the 1800PS engine output comes from, it was fitted on early Kurfurst only. The DB605DM is an evolution of the DB605D-2 with MW-50 injection like the DB605A/AM couple.

And there was the DB605DB/DC, this engine could be set to function on either B4 or C3 and with a different max power output.
- The DB was set for 1850PS @ 1.8ata using C3 or B4+MW50.
- The DB605DC could be set for a max boost of 1.8ata or 1.98ata
If the DC was set at 2000PS @ 1.98ata this output could be reached by using C3+MW50, when using C3 alone, output was just 1725PS@1.8PS, way lower than the DB605DB. If the DC was set for a max boost of 1.8ata, power output was 1800PS which was achieved by C3 alone.
The DB/DC was easily convert one into another so using B4 or C3 was not much of a problem on those aircraft."

It appears the DB and DC were introduced fairly early : the respective manual for these engines, dated 5th December 1944, was already the 3rd edition of it`s kind. As K-4 production only geared up from about October 1944, we can safely state most of them had DB or DC powerplants, most likely already from November 1944 onwards if not earlier. Certainly the performance was not determined by the ealry DM powerplants alone for most of the time, as Williams suggests.

To clear up the issue, the correct level speeds :

Maximum level speeds obtained with various boosts on the Bf 109 K-4 with 1.75ata (DM), 1.8ata (DB) and 1.98ata (DC)

Note early production batches only DB and DC, as on most machines Above rated alt identical to DB/1.8ata
Engine type, boost, and power output at SL DB 605 DM,

1.75ata, 1800 PS

DB 605 DB,

1.8ata, 1850 PS

DB 605 DC,

1.98ata, 2000 PS


Source GL/C- E2, Stand vom 11th August 1944. Graphs 'Leistungen 8-109 K4 u. K6.' Mtt. A.G., 11th December 1944.
Speed at SL 580 kph or 360 mph 594 kph or 369 mph 607 kph or 377 mph
Speed at rated altitude 710 kph at 7.5km or 441mph at 24 600 ft

715 kph at 7.5km or

 444mph at 24 600 ft

715 at 6km to 7.5km or

444 mph at 19 600 ft - 24 600 ft


"The November 1944 edition of the Bf 109 K-4 Flugzeug-Handbuch states:

which translates to: The MW installation serves to increase the emergency power of the engine. With 1,75 ata boost pressure, additional injection of MW increases emergency power (special emergency power) and can occasionally be used to increase level speed and rate of climb. The MW additive serves for the interior cooling of the engine and for the avoidance of overheating during flight with special emergency power. The use of the special emergency power without MW injection is forbidden! The engine is endangered without MW injection. The withdrawal of the special emergency power is done via putting the throttle lever forward on 1,75 ata boost pressure (number of revolutions 2850 U/min). "


Again there`s some confusion about the correct date of the manual; Williams states it refers to November 1944, but again it`s the case of the 'Stand' (the date the given information in the document is valid for) and 'Ausgabe' (the date issued) mixed up. Again referring to the original document`s cover page it becomes clear that the source in question reflects the conditions as of in October 1944 ('Stand Oktober 1944'), and was issued early in November; as the following page notes : 'Rechlin, den 7. November 1944'. This is an eary manual for the K-4, for the early batches with the DB 605 DM engine, that run only at 1.75ata.  Most likely the only goal quoting the document is to prove that even in November 1944 (hence the little trick with the datum), no more than 1.75ata could be used. That`s right - for the DM engines, which saw little service...

The translation is also rather poor; this may be due to using online translators for the task. ie. the text doesn not say about special emergency power that it cannot 'can occasionally used', but in given periods of use (zeitweise Entnahme). And as a sidenote, pushing (not putting) the throttle lever forward to the max. boost does not 'withdraws' the Sondernotleistung, but engages it.

The use of the maximum power, the Sondernotleistung (WEP or Combat power in US/British terminology) could be used for a maximum of 10 minutes at a time. This underlines that the Sondernotleistung was far from being a momentary boost of power, used on 'occasion'.

From the Bf 109 K-4 Handbuch :

   "Der mitgeführte MW-Stoff (75 Ltr.) reicht für 26 Flugmin.-Sondernotleistung aus. Es kann also 2 x 10 min Sondernotleistung entommen werden, oder eine andere Zeitaufteilung; auf keinen Fall mit Sondernotleistung über 10 min fliegen. Weiteres über Bedienung siehe L. Dv. T. 2109 K-4/Fl.

    Zwischen zwei Sondernotleistungen muss eine Betriebszeit mit geringer Motorleistung von mindestens 5 min liegen."

    "The amount of MW booster fuel being carried (75 liters) is sufficient for 26 minutes of flight while using the Sondernotleistung. Therefore  Sondernotleistung can be used for two 10 minute periods, or in any other subdivision; in no case should one fly with Sondernotleistung for over 10 minutes. For further servicing instructions, see  L. Dv. T. 2109 K-4/Fl.

    Between two uses of the Sondernotleistung the engine must be run at a lower power output for ca. 5 minutes."


In comparison to the Bf 109 K-4`s 10 minute limitation of running at maximum power, the Griffon 65 engine of the Spitfire XIV was limited of 5 minutes of run at maximum power, as according the the Pilot`s notes for the Spitfire XIV and XIX.

Back to the question of maximum allowed boosts, the already mentioned  manual for the DB 605 DB/DC engines issued 5th December 1944, already the 3rd edition of it`s kind, notes the use of both 1.8 and 1.98ata for the DB/DC, respectively. According to the recordings of a meeting on the 20th January 1944, after unsuccessfull trials at Rechlin Test Centre, the clearance of 1.98ata was delayed until further testing is performed; particular interest is Gen. Ing. Paul`s criticizing
Daimler Benz as it forwarded the clearance of 1.98ata boost directly General Galland, General of the Fighter Arm, and the Technisches Ausendienst for 'diese Leistungen direkt der Truppe angeboten wurden und die Motoren umgestellt werden' or because it issued these boost (1.98ata) directly to the troops and set the engines to it. Further the document states that individual fighter-recons may be set to 1.98ata. Given the date of the manual and the meetings and their contents, we can be sure 1.98ata was already in use for some time during December until late January, when the boost was recalled for further testing with II./JG 11.

This is underlined by the 'Leistungen 8 - 109 K4 und K-6 mit DB 605 ASCM/DCM. Oberammergau, den 11.12.44' performance report itself, which Mike Williams used for his graphs, and which refers to, in mid-December to 1.98ata as per specifications from Daimeler-Benz (DB Angaben 9-605-2290), as seen above..


"Niederschrift Nr 6730 of Daimler Benz dated 24 January 1945 states: Testing of 1.98 boost pressure may be done provisionally at group 2/11, the rest of the tests with appropriate engines already started having failed. Only engines with 1.8 boost may be supplied. Strict punishment is threatened if this instruction is neglected. (Nach Lage der Dinge wird denn festgelegt, dass vorläufig die Erprobung des Ladedruckes 1,98 ata nur bei der Gruppe 2/11 durchgeführt werden darf, und dass im übrigen nur die bereits angelaufenen Erprobungen mit entsprechenden Motoren ausgefallen sind. Der Nachschub für diese Motoren darf dann nur mit Motoren mit Einstellung 1,8 ata Ladedruck erflogen. Bei Nichtbeachtung dieses Befehls wird strenge Bestrafung angedroht.)"

Mike Williams here qoutes the mentioned recordings of a meeting from the DB archieves. Part of the text was taken, out of context, and was mis-translated resulting a completely different meaning. Part of the original German text was also left out by Williams, where it tells tests with 1.90 ata manifold pressure are already being carried out:

"...und dass im übrigen nur die bereits angelaufenen Erprobungen mit entsprechenden Motoren ausgefallen sind..."


"...und dass im übrigen nur die bereits angelaufenen Erprobungen mit 1,9 ata zu Ende geführt werden dürfen bis die entsprechenden Motoren ausgefallen sind..."

See in the original German document. To summerize, Mike Williams`s version of the original seems to fit his own aganda, and was used as proof for that 1.98ata was never used....

The complete text and it`s translation is as follows :

Original German text Correct translation (checked by native speakers) William`s version of the underlined text:

Nach Lage der Dinge wird denn festgelegt, dass vorläufig die Erprobung des Ladedruckes 1,98 ata nur bei der Gruppe 2/11 durchgeführt werden darf, und dass im übrigen nur die bereits angelaufenen Erprobungen mit 1,9 ata zu Ende geführt werden dürfen bis die entsprechenden Motoren ausgefallen sind. Der Nachschub für diese Motoren darf dann nur mit Motoren mit Einstellung 1,8 ata Ladedruck erfolgen. Bei Nichtbeachtung dieses Befehls wird strenge Bestrafung angedroht. Die Genehemigung zur Einstellung 1,98 ata darf ausschliesslich nur durch die Abtlg. VI des Generalstabes erteilt werden.

Seitens der Herren das Chef-Ing. wird vorgeschlagen, evtl. auch einzelnen Aufklärer mit dem Ladedruck 1,98 ata auszurüsten. Eine Entscheidung hierüber ist jedoch nicht gafällt worden.

Zur thermischen Entlastung der mit 1,98 ata und 1,90 ata eingestellten Motoren wird festgelegt, dass auch diese das spätgestellte Zündprogramm erhalten. Somit werden also all Motoren, die mit der sogenannten Sondernotleistung geflogen werden, auf die späte Zündung umgestellt.

After the delays in the matter, it has been laid down, that testing of 1.98ata manifold pressure is foreseen to be proceeded with only with the Gruppe 2/11, otherwise only the already initiated tests in process with 1.9ata manifold pressure are to be completed,  until the the said  engines fail. The replacements for these engines should be with the 1.8ata setup only. Not following this order will result in severe punishment. Permission for adjusting for 1.98ata can only be given in cooperation with Department VI. of the General Staff.

On behalf of the Chief Engineer`s men it has been presented, that it may be possible to equip single fighter-recons to 1.98ata manifold presure. Decision has not been taken on this yet.

Delayed ignition is to be used with engines at 1.9ata and 1.98ata setups, as a result of the termal load that had been observed with them. Therefore all engines, that are flown with the abovementioned Sondernotleistungs, are to be set to delayed ignition.

  • "Testing of 1.98 boost pressure may be done provisionally at group 2/11"


  • "the rest of the tests with appropriate engines already started having failed. "


  • "Only engines with 1.8 boost may be supplied. "
Only the text in Italics was quoted by Mr. Williams - the rest was ignored. The underlined text/translation was left out for some reason.


It should be noted, that the same complete translation could be found at the same place as the documents, therefore Mike Williams had every chance to get the correct meaning and translation of the text. He choosed not to, and he choosed to come up with his own, and present it as such in his article. The above example is a typical summary of the way Williams uses his references.


Olivier Lefebvre, noted authority on the BF 109, has stated:

The DB605DM was cleared up to 1.75ata, the DB605DB pushed the limit up to 1.8ata, both could be sustained with use of either B4+MW-50 (as mentionned in various documents, even if it was an afterthought in the DM case) or C3-MW-50. However the DB605DC max boost at 1.98ata could be achieved with use of C3+MW-50 only.

As for the fuel supply, I own copies showing detailed stockpile status for February-April 1945... But yes the C3 was definitely scarce.

As of March 1945 only a handful of 109 gruppen were using C3 for their mounts, one of the few being the II/JG11 which were responsible for testing the 605DB/DC over January-March 1945. According to a document dated late January 1945 coming from DB the 1.80 had just been cleared following serious troubles (pre-ignition) reported by the unit testing the 1.80 ata boost. It is also noted that following the clearance of the 1.8ata boost the 1.98ata operational tests could now begin but with concern about the sparkplugs thermal resistance IIRC. C3 was not used by 109 units until the 1.98ata boost was cleared, they relied on B4+MW-50 so that C3 could go to the 190 units. And even after the clearance only few gruppen got it because of shortages due not only to C3 production but also to C3 delivery to the units.

AFAIK 1.98ata boost was cleared late February but it seems to have been slowly introduced into service, I suspect the adjustments needed on the engine and the change of sparkplugs type (supply problems ???) took longer than expected. From other documents I know that C3 and B4 had severe quality problems beginning in late 1944. While it was not much of a problem with low boost, it had some serious effect on higher boost, so it might also have slowed down the introduction of 1.98ata boost. At least DB documents underlined the need for cleaner fuels than those in use at that time. You can safely assume that by March 1945 1.98 ata boost was being introduced, unfortunately I do not have much details for April 1945, but I doubt it would have changed much, given the situation.

"No evidence has come to light proving operational use of 1.98 ata by combat units, however, given the desperate situation of Nazi Germany in the Spring of 1945 its natural to assume caution would have been thrown to the wind and it might have been tried, if there were sufficient stocks of C3 fuel - which seems unlikely. None the less, in light of the severe thrashing of the Nazis in Spring 1945, such measures amounted to little more than pissing in the wind. "


Apart from the really elegant last sentence, the statements of Mr. Williams lack the connection with the reality. Personally, I find it a bit absurd that Williams manage to state that 'no evidence has come to light proving operational use of 1.98 ata by combat units', right after qouting Olivier Lefebvre who stated that II./JG11 using 1.98ata to gain operational experience. I cannot imagine what else could be the II. Gruppe of the Jagdgeschwader 11 than a pure combat unit, and which had eleven Bf 109K-4s and thirty-eight Bf 109G-14s on strenght (plus a single G-6/U2) on the 1st January 1945, having lost twenty-eight G-14s alone in December to enemy action according to it`s strenght report...

Furthermore, the statement, or the better, denial becomes futile in view of the orders issued to units to increase boost pressure to 1.98ata, according to a classified order dated 20th March 1945 from the LW high command (OKL, Lw.-Führüngstab, Nr. 937/45 gKdos.(op) 20.03.45) :

"The development in the equipment status of day fighter units is based on the standard types laid down in the emergency program and anticipates :


for Bf 109 units    : K-4

for FW 190 units : D-9, D-12 with changeover to Ta 152 H and C


The arrival of the Ta 152 and it`s assignment to FW 190 units will result in an improvement in the equipment status of these units.

Essentially Bf 109 development will conclude with the K-4 an will inevitably lead to the conversion of Bf 109 units - those not scheduled for disbandment - to TL (jet fighters). Homogeneity of the equipment is to be strived for, combination of similar types is temporary and to be accepted based on levels of production."



The proposed changes to units equipped with Bf 109 were as follows :


OKL, Lw.-Führüngstab, Nr. 937/45 gKdos.(op) 20.03.45

No. Unit Present type Convert to Notes
1. III./ JG 1 Bf 109 G-10 He 162 (April/May) -
2. II. / JG Bf 109 G-10 K-4 when deliveries permit -
3. III. / JG 3 Bf 109 K-4 no change -
4. III. / JG 4 Bf 109 K-4 no change -
5. IV. / JG 4 Bf 109 K-4 K-4 -
6. III. / JG 5 Bf 109 G-14 K-4 when deliveries permit -
7. IV. / JG 5 Bf 109 G-14 K-4 when deliveries permit -
8. III. / JG 6 Bf 109 G-14/AS K-4 when deliveries permit -
9. II. / JG 11 Bf 109 G-10 K-4 when deliveries permit -
10. I. / JG 27 Bf 109 K-4 no change boost increase to 1.98 ata
11. II. / JG 27 Bf 109 G-10 K-4 when deliveries permit -
12. III. / JG 27 Bf 109 G-10 no change boost increase to 1.98 ata
13. I. / JG 51 Bf 109 G-14 K-4 when deliveries permit -
14. III. / JG 51 Bf 109 G-14 K-4 when deliveries permit -
15. IV. / JG 51 Bf 109 G-14 K-4 when deliveries permit -
16. II. / JG 52 Bf 109 G-14/U4 K-4 when deliveries permit -
17. III. / JG 52 Bf 109 G-14 K-4 when deliveries permit -
18. II. / JG 53 Bf 109 K-4 no change -
19. III. / JG 53 Bf 109 K-4 no change boost increase to 1.98 ata
20. IV. / JG 53 Bf 109 K-4 no change boost increase to 1.98 ata
21. I. / JG 77 Bf 109 G-14/U4 K-4 when deliveries permit -
22. II. / JG 77 Bf 109 G-10 K-4 when deliveries permit -
23. III. / JG 77 Bf 109 G-10 K-4 when deliveries permit -
24. III. / JG 300 Bf 109 G-10/R6 via K-4 to Me 262 planned, deadline
25. IV. / JG 300 Bf 109 G-10/R6 via K-4 to Me 262 -
26. I. / KG(J) 6 Bf 109 G-10/R6 K-4/R6 when deliveries permit -
27. II. / KG(J) 6 Bf 109 K-4 K-4/R6 when deliveries permit -
30. I. / KG(J) 27 Bf 109 G-10/R6 K-4/R6 when deliveries permit -
31. I. / KG(J) 55 Bf 109 G-10/R6 - -
32. II. / KG(J) 55 Bf 109 K-4 - to industrial defense
33. Ist Italian FG Bf 109 G-10 K-4 when deliveries permit -
34. IInd Italian FG Bf 109 G-10 K-4 when deliveries permit -
35. IIIrd Italian FG Bf 109 G-10 K-4 when deliveries permit -


This order, apart from ordering 90% of the existing 109 units to convert to the Bf 109 K-4 as soon as deliveries permit, also notes in relation of I./JG 27, III./JG 27, III./JG 53, IV./JG 53 to increase the maximum boost pressures to 1,98 ata manifold pressure. It is not known if and how many units had converted to 1,98ata before that order came, but it should be noted these units, in particular III./JG 27, III./JG 53 and IV./JG 53 were the major users of the Bf 109 K-4 in the Lufwaffe.


Overview of unit strenghts for the units that used 1,98ata. As per 9th April 1945.

The list of 1,98ata units is most likely incomplete. Source : Alfred Price : The Last year of the Luftwaffe

Unit On hand Servicable Type
II./JG 11 N/A N/A Bf 109 K and G
I./JG 27 29 13 Bf 109 K
III./JG 27 19 15 Bf 109 K and some 109 Gs
III./JG 53 40 24 Bf 109 K and some 109 Gs
IV./JG 53 54 27 Bf 109 K and some 109 Gs
Total 142 79  

The comparison of Bf 109s with units running at high manifold pressure of 1.98ata can compared to the theoretical  number of Spitfires (5 Squadrons out of 7 being used with +21 lbs in 1945, a maximum of 100 planes counted with 20 planes per squadron, which included 8 reserve planes per squadron as well. See below)


Total On-hand strenght of 1st line Bf 109 combat units, without their associated Erganzungs (2nd line) units, on 31st January 1945.

Source: RL2III/1158.

Type Number of aircraft on hand Percentage Medium/High altitude types Max. level speed.
Bf 109 G-6 71 4,9 %

Medium altitude types :

502 fighters, 35 % of the total

665 kph at 5 km
Bf 109 G14 and G-14/U4 431 30 %
Bf 109 G-10, G-10/U4 and G-14/AS 568 43,1 % High altitude types :

933 fighters 65 % of total

680 - 690 kph at 7,5 km
Bf 109 G-10/R6 51
Bf 109 K-4 314 21,8 % 710-715 kph at 7,5 km

1435 Bf 109s with the first line units,
without reserves in 2nd line units and aircraft storage centers

Spitfire strenght in late 1944/45

The SHAEF`s order to the 2nd TAF in a comparable timeframe at the turnover of 1944/45 shows 30 Squadrons are equipped with the older Mk IX. and XVI. Spitfires with a maximum speed of  650 kph at 5900m / 404mph at 19 600 ft, while only 5 Squadrons being equipped with the newer Mk. XIVs.

In comparison, according to Neil Stirling, as on of 14th December 1944, there were altogether 120 Spitfire Mk. XIVs. with the operationally fit Squadrons:

  •  41 Squadron,

  • 130 Squadron,

  • 350 Squadron,

  • 402 Squadron,

  • 610 Squadron,

  • 430 Squadron

  • 2 Squadron.


In view of the above, and the relative number of aircraft on operation, wheter the the Bf 109 K or the Spitfire Mk XIV was faster by as little as 5 mph at any given altitude makes little importance - the existance of a handful of modern MkXIVs was barely noticed either by the RAF or Luftwaffe. The vast majority of RAF squadrons flew the old Mk IXs until the cease of hostilities, and certainly they felt that 40-50 mph speed differenence between their Mk IX rides and the Luftwaffe G-14/AS, G-10s, K-4s and D-9s.



"The best thing about the Spitfire Mk. XIV was that there were so few of them".

- Adolph Galland, General der Jagdflieger.




Sources, Notes and References


Notes :

This article is soon to be supplemented with a more complete list of sources, as well as with a fair comparision performance graphs.

Ideas and suggestions, critics are most welcome. Email at .


Primary Sources :

  1. OKL, Lw.-Führüngstab, Nr. 937/45 gKdos.(op) 20.03.45
  2. Niederscrhrif Nr. 6730. Daimler-Benz AG,  Sektor Entwicklung. 20.1.45
  3. Leistungen 8 - 109 K4 und K-6 mit DB 605 ASCM/DCM. Oberammergau, den 11.12.44 and 1.19.45. Messerschmitt AG.
  4. GL/C- E2 Flugzeug Entwicklungsblatt Bf 109 (J) 1.11.44. G-14/ASM, G-14/U4, K-4
  5. GL/C- E2 Flugzeug Entwicklungsblatt Bf 109 (A) 1.11.44. G-14/ASM, G-6/R2, G-6/R5, G-10/R2
  6. GL/C- E2 Flugzeug Entwicklungsblatt Bf 109 (J) 1.11.44. G-14/ASM, K-4, K-6, K-14
  7. C-Amt Monatsmeldungs of 1944, of G-6/AS production
  8. Pilot`s notes for Spitfire XIV and XIX.
  9. Bf 109 K-4 Flugzeug Handbuch. Stand Oktober 1944, Ausgabe November 1944.
  10. Zusammenstellung der Leistungseinflüsse verschiedener Anbauten

Secondary Sources :

  1. Fritz X. Kober - Jakob Maria Mathmann : The Messerschmitt Bf 109 Vol.2. Schiffer Publishing, 1996.
  2. Heinz Knoke - I flew for the Fuehrer. Greenhill books, 1997.
  3. Alfred Price : The Last year of the Luftwaffe. Greenhill books, 2001.
  4. Jerry Scutts : Spitfire in Action, Aircraft No.39 - Squadron Signal Publications. Page 26.


10th March, 2005.