109 test flight reports
The problem with Me performance numbers
When talking about the Messerchmitt 109 performance, we must take into account that many western sources are simply wrong. They are based on original wartime allied test flights flown with damaged planes, or with such equipment that the planes do not represent a normal fighter variant. Also western sources often fail to quote the used power setting. Was the engine runnign on continuous, 30 minute or 5 minute power? Western performance numbers (US/FAF/RAF) are always quoted with maximum power settings. Luftwaffe standard was to test all climb and level speed performance with the 30 minute setting, which really gives a more "real life" performance. Some Allied tests are quite good, but especially Me 109 tests are often very suspicious.
A good example this are the 109 F-4 tests. The only test flight of the type was flown by the RAF. All other "tests", American reports included, are copies of the British test. US never flew a single test flight of a Me 109 F-4 and their "report" fails to mention that the plane ran roughly, engine was derated and did not develop its full power, hence "the numbers must be regarded as absolute minimum performance for the plane". These numbers have since changed into gospel in western aviation literature, and these numbers are copied from book to book as the maximum performance of the plane.
German level speed tests are usually recorded with "Steig & Kampfleistung", "climb & combat" power, 30 minute maximum.
The "Start & Notleistung" - "takeoff and emergency" setting was not in tests. If it was used, the sheet mentions it. These settings were usually available for 1 to 5 minutes, depending on engine series, hence it is often referred as the 5 minute power setting.
But what is the reliability of German tests? Some have argued that they are propaganda and cannot be trusted. Incorrect. For example with the 109s, RLM had aggressively committed themselves to the Me 109 as the only single-engined fighter the Luftwaffe was going to purchase, and there was no competition at all. The Kennblatt figures weren't provided for the benefit of the marketing department, but they were the yardstick against which the aircraft delivered by Messerschmitt were measured. Failing to meet the figures would result in customer complaints, corrective action and financial consequences - and in the Third Reich perhaps even more severe results. If anything, the factory and test flight centers produced usually very accurate information. As the Finnish State Aircraft Factory test flight pilots commented, only two of all the fighter planes delivered to FiAF in the war years actually matched the factory papers: the Brewster B-239 and Messerschmitt 109. Other types, including the British, French, American and Italian planes, different often wildly from their "paper performance".
RAF Royal Aircraft Establishment (RAE) Farnborough handling trials,Bf.109E Wn: 1304. http://www.geocities.com/capecanaveral/hangar/9378/flybf109.html
Messerschmitt Me (sic) 109 Handling and Manoeuvrability Tests, M.B. Morgan and D.E. Morris, Communicated by the Principal Director of Scientific Research - Air, Reports and Memoranda No. 2361, Great Britain, September 1940. (Probably also using data from RAE Jan 1941 testing).
Comparitive Trials between Me109E and British Fighter Aircraft, RAE (?), 14 August 1941
Here we have two interesting reports. They're actually a 1941 report from tests conducted in September of 1940 from an aircraft that was captured by the French in 1939 (see next chapter). At the time the tests were conducted in 1940, they didn't have oxygen bottles for the 109, so test could only be done at low to medium altitude, where they thought combat would take place anyway. At these altitudes the result was indeed that both the Spitfire and Hurricane could out-turn the Bf109, and this was reported to the squadrons, whose pilots would have reacted in combat according to this perceived strength. Later, well after the Battle was over, testing at higher, "combat" altitudes showed the opposite to be true at these heights.
There is even more confusion. The 109 tested is claimed to be "Me 109E-3 Werk-Nr 1304" which is documented to have been captured. However, there is some discrepency as to WerkNr 1304 actually being an Me109E-1. So what have they tested? E-1? E-3? E-4? Did they test one of the crash landed, damaged planes? So we got major confusion with the tested plane. Also, Bf 109 E-3 WNr. 1304 (RAF AE 479) was at one point crash landed, among other things, and it received a new tail section from a Bf 109 E-4 WNr. 1980.
Another problem is with the test itself, when compared to a Spitfire. Overall the accuracy of the test suffers from the fact that it was flown with a crash landed plane wirh a worn, several years old engine producing less power than usual. It was then flown against a brand new Spitfire with a 1940 engine. As shown by the test data, the turns were made in the 120mph range which is too slow for the 109 slats to be deployed, which doesn't compare the maximum turning abilities of each aircraft. Further inspection of the report will show that the test was conducted with the "Rotol" Spitfire. The Rotol Spitfire had a Merlin III engine, not the Merlin II. At 11,000 feet it had a climb rate of 2,905 ft/min, the turn test was conducted at 12,000ft. This test was conducted 19 March 1940. Now look at the other two Spitfires in the test. Their test date was in July 1939. The climb rate of the 1939 aircraft at 12,000 feet was only about 2,000ft/min vs the 2,900 ft/min of the Rotol aircraft. The Rotol aircraft is inconsistant with the performance of the aircraft in the field. The 109 was captured in 1939, therefore for an accurate representation to be made it should be compared to other 1939 aircraft. We are talking about taking 1940 technology and applying it to a 1939 matchup, taking an aircraft with 45 % more climb rate than aircraft available at the time the 109E was in service in 1939.
The 1940 report clearly states that the performance of the 1939 aircraft was not even near equal to that of the 1940 test (2100ft/min vs 2900 ft/min @ 10,000ft). The 109E matchup was done with the Spitfire employing 1940 technology, a constant speed propeller that was not in use in 1939. The matchup was also done with a Merlin III engine that was not available in 1939 aircraft. Also, it was done with a captured battle worn aircraft of questionable service against a brand new aircraft. The report does not state the maximum speed of the 109E by which one could gauge the relative engine horsepower output compared to other known DB601 engines. Also, it doesn't state a matchup between the 109E and Spitfire MkI employing a Merlin II engine and a standard propeller at the time, rather with the new 1940 constant speed propeller.
The French flew their test with the same Me 109 E-3 (E-1?). The test results are not available in English, but to author's knowledge their recorded performance numbers are higher than in the British tests. Since British tests do not give the used power setting, it is extremerely hard to find the truth between different test results.
References: Impossible to Follow? http://users.bigpond.net.au/mantis/FW/Bob/Best.htm
The 109 tested is claimed to be "Me 109E-3 Werk-Nr 1304" which is documented to have been captured. http://www.luftwaffe-experten.co.uk/usa.html
However, there is some discrepency as to WerkNr 1304 actually being an Me109E-1: http://www.ww2.dk/pictures.html
Could this aircraft have been mixed up with other E-1's and E-3's captured and may have been damaged resulting in lower performannce: http://www.luftwaffe-experten.co.uk/allied.html
Case: French test report of the above aircraft, White 1, WerkNr 1304, AE479:
Read it here
This is the test of White 1, WerkNr 1304, AE479. It was captured in 1939 and tested by the French, where they made a couple dozen flights testing it against a D.520. During a high power climb test, the engine malfunctioned due to lack of proper oil and coolant. The aircraft was subsequently handed over to the British, who tested up until September of 1940 or after, nearly a year after it had been captured.
The important things to note are that the climb rates listed are based on averaging time to climb. There is also a second climb table near the very end of the report that appears to correct the original. I believe the second table reflects climb with the radiators in a different configuration. The French seem to have considered 1100 PS, 1.4 ata as the 5 minute setting. The climb table looks to have been compiled at that power setting. There is also a table of Vmax values along with the altitude, rpm and MAP for each speed. The one I found most interesting is 490 kph at 2500 meters, 2400 rpm and 1.26 ata ( 960 mm Hg ). I make that 990 PS, 282 mph Vmax at sealevel. But, my speed conversion from altitude to sea level could be wrong. If I grokked the comment after the last part of the report, they roasted the engine during testing. This is important to note, as the British tested later the same 109!
Or to make things yet more confusing, did the Brits test two different Emils? The Rolls-Royce speed tests were only done at partial power and with radiators open (or I'm missing the pages with full-power tests), but they conform well with the French speed tests at full power and with radiators open. The conclusion is that the French speed data, though not calibrated, is nevertheless correct (or even slightly low). In other words, the French top speed figure of 570 km/h for the Me 109E-3 is perfectly realistic. What's more, the French had an early DB601A with the low full throttle height, a late-model DB601A (which became available at some time between December 1939 and August 1940) would have given an even higher top speed due to the reduced air density at the higher full throttle height.
This French test was flown with open radiators up to 4000 meters, then gradually closing the radiators up to 8300 meters. At that time test had to be abandoned due to engine problems, as the engine malfunctioned. They related that to the temperature outside. The temperature was +6c on the ground and -17c at 5000m. The French considered it possible to make the climb radiators closed, which would enhance climb rate. Engine problem stems most likely from the French substitute oil and coolant, that had a lower calorific value which induced serious engine troubles.
Also note that the 109's leading edge slats may have been taped shut during these tests. Both the French and the British used this captured aircraft in mock dogfights to test the relative performance of the aircraft to the D.520 and the Spitfire. The French and British may have been so afraid of the slats, that they taped them shut so as not to interfere with their maneuvering during mock dogfights. Almost all jet aircraft today have leading edge slats to increase lift during takeoff and landing. Most military jets automatically regulate the use of slats during maneuvering. If these slats were operational on this particular 109, there would have been a marked change in the stall boundary when the wing camber changed due to deployment of the leading edge slats. This change is not present in the graph. The only conclusion that can be made is that the slats were not operational during testing. Without use of operational leading edge slats to increase lift at low speeds and high g's, the entire stall boundary curve on this graph is not representational of combat aircraft.
So the conclusion? The French data, supported by the Rolls-Royce data, suggests a top speed of 570 km/h (or above) at 1.2 ata. WEP is 1.3 ata. The French data is for an early-type DB601A with low full throttle height, while at the time of the Battle of Britain, the new type with increased full throttle height and accordingly increased top speed was available. The French data suggests a 482 km/h sea level speed. This is confirmed by the Me 109V15a (the Emil prototype) which achieved a sea level speed of 486 km/h @ 951 PS. (The DB601A-1 provides 990 PS at sea level at the 5 min rating.) The French climbed to 5000 m in 6:18 min with radiators fully open in an aircraft that probably wasn't cooling correctly.
Case: Bf 109 E-3/4
Auszüge aus Flugzeugdatenblatt Bf 109 E-1, E-3 nach L.Dv.556/3. German flight test numbers.http://www.virtualpilots.fi/feature/articles/109myths/kuvat/emil_4785a2b8.gif
Case: Me 109 F-4
Practically all Me 109 F-4 its performance reports stem from a single British test flown with a damaged airplane with derated engine. All other test "reports" are copied from this one test.
In summary, from the article: " After the review of several hundred pages of British reports about planes of the variants Bf 109 F-1/-2/-4 the picture became apparant, that only with exactly one captured Bf 109 F-4 and its engine performance measurement were done. As already the climbing time, then also the British maximum speeds give a clear reference to, that the available engine did not even obtain the power output for climb/combat power. As best climbing rate for the climbing on 4876 m are indicated about 1006 m/min, for the climbing on 6705 m 8.2 minutes. Again these are values, which were clearly below the German for climb/combat power. These were on one hand a maximum climbrate of 1111 m/min for the climbing to 5000 m. The British values for the maximum climbrate lay thereby even below the German mean value. On the other hand according to German data sheets the climb time to 7000 m altitude was 7.4 Minuten.
The American test, "Combat Evaluation Report Nr. 110" for the Bf 109 F, 7th February 1943", are only a compilation of the British test reports sent to the USA and no American flight tests were flown with F-4s. And to top it, the transferred report is riddled with errors in converting the numbers and drawing the performance curves. For example the reported climb rate is the British climb time for 16,500 feet converted to 15,000 feet. Also in the American summary are existing further serious transfer errors. This becomes clear due to a comparison of the fire trials results from the British and the American test. In the British original version is told, that .5" B. Mk. II armor penetrating ammunition had no chance to penetrate the pilot armor of the Bf 109 F-4 under the listed conditions, if the projectile punched in below the fill level of the fuel tank. In the US version this projectile received a 30% chance for penetration of the pilot armor independing of the location the fuel tank was entered. This way on the US side the British firing trial results were wrongly mixed for .5" and 20 mm ammunition.
On the British sources all test protocols are missing, which would document the real power output of the DB 601 E during the test flights by telling boost pressure and revolutions per minute. Also complete top speed/climbtime curves instead of the few listed measurement points would be very helpfull. The source situation permits nevertheless to make some evaluations. The German sources present for the whole timeframe from sommer 1941 till spring 1943 consistent performance values for top speeds as well as climb ability. There was clearly differentiated between the power settings take off/emergency power and climb/combat power. The period of the initial prohibition of use of the take-off/emergency power of the DB 601 E could be narrowed down very exactly. For the British sources it is totally unclear with which engine power settings the test was flown. Problems with the available engine were indicated, but not mentioned in the final report. Additionally there were inconsistent specifications, like the reaching of higher speeds in spite of a higher weight specification for the test plane. Anglophone authors seem to have known the German sources not at all. The performances told by them are all in a range, which is only told by Allied sources."
Source: Article about the performance of the Bf 109 F-4, written by Michael Rausch.
Case: AFDU 28 October 1941: Tactical trials - Me.109F aircraft
4. The controls are well balanced and the aircraft is pleasant to fly, but is not so easy to take off as the Me.109E. The elevator control is fairly heavy but the rudder control is light and is effective even at low speeds, the aircraft being very sensitive to over-correction on the rudder during take-off. The Me.109F is not as easy to land as the Spitfire, although it is a little easier than the Me.109E, due to its slightly better forward view. The speed of appraoch for landing is about 110 m.p.h. and the angle is rather steep, which necessitates a big change of attitude before the final touch down. Although the landing speed is high, the resultant run is short and brakes can be safely applied as soon as the aircraft is on the ground.
7. No manoeuvrability trials were carried out against other aircraft but the Me.109F was dived up to 420 m.p.h., I.A.S., with controls trimmed for level flight and it was found that although the elevators had become heavy and the ailerons had stiffened up appreciably, fairly tight turns were still possible. [...] It is considered that recovery from a high speed dive near the ground would be difficult, as the loss of height entailed is considerable. This may account for occasional reports of Me.109F being seen to dive straigth into the ground without apparently being fired at.
Case: Me 109 G-2
There are some trustworthy numbers of the 109s as well. The Finnish test flight report of Me 109 G-2 "MT-215" was flown 6.5.1943 by captain Pekka Kokko, famoust Finnish test pilot, with a regular combat squadron plane with full combat equipment, including all ammo for all guns and full fuel load. The report specifically mentions the radiators opening fully at some points during the climb test. The max-speed tests were run with the radiators manually shut. Its level speed peaked at about 6400 meters at roughly 645 km/h on 30 minute power setting. The climb rate peaked at 2000 meters when the plane grabbed altitude 24,7 meters per minute. Height/climbrate: 3000m / 18,9 m/sec - 4000 m / 17,2 m/sec - 5000 m / 17,2 m/sec - 6000 m / 15,1 m/sec - 7000 m / 13,4 m/sec - 8000 m / 13,7 m/sec, 9000 m / 9,0 m/sec, 10 000 m / 5,9 m/sec. Climb to 4000 meters: 3,2 mins - 5000 meters: 4,1 mins - 6000 meters: 5,1 mins and 8000 meters: 7,6 minutes.
Other data: stall speed clean 170 km/h (could not be clearly defined). The nose sunk and the plane banked calmly to the right wing. At landing configuration the stall speed was 145 km/h. With full power the plane could be held hanging from the prop at 60° nose-up attitude ASI showing 130-140 km/h. Up to 350 km/h with a hard pull in the bank plane could be stalled (!) At 1000m altitude 180° turn required 10 s (G-2), starting speed 450 km/h, final speed 380 km/h. Full circle 18 s with final speed 330 km/h. Full 360° bank required 22 s with 360 km/h, bank angle 70° acceleration 3 g.
Case: Me 109 G-6
For example 109 G-6 model's performance numbers are usually quoted from a flight test flown by mr. Brown. The actual plane was a 109 G-6/U2, which is a three cannon night fighter variant with night fighting equipment. Authors now take these numbers, drop away the information that it was a 3-cannon night fighter and voila, we got weak performance numbers for the G-6. The 3-cannon night fighter G-6 made 621 km/h in 30 minute power setting. A clean G-6 does 635-640 km/h with 30 min setting and 650+ km/h with 5 min WEP setting. So you can see that the wing cannons not only decreased speed, but they decreased the climb rate, roll rate and overall agility of the plane.
Case: Spitfire Mk XIV versus Me 109 G/K A Performance Comparison
An article looking and correcting the errors at Mike Williams's "Spitfire Mk XIV versus Me 109 G/K A Performance Comparison" article. The foreword says: 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. The article can be read at http://users.atw.hu/kurfurst/articles/MW_KvsXIV.htm.
Quotes from the article:
"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."
Me 109 G-14
Allied examination of a captured plane, W.Nr. 413601, can be read at 109 Lair by selecting Articles / evaluations / G-14.
Something to read
"Messerschmitt Bf 109 A-E, Development - Testing - Production" by Willy Radinger & Walter Schick. In the foreword it states that work on the book was begun in 1994 and Walter Schick died in 1995. It states he is writing the book to correct the many errors that have crept into aviation books over the years. Several Messerschmitt employees helped out in the book, one of which is Lukas Schmid who began working there in 1934 and was group leader on the project in 1937 and subsequently a flight test pilot.
The book lists many statistics, even the Werknummer of the prototypes and types of aircraft produced in low numbers. It also contains a reproduction of the certification of the 11 November 1937 world speed record flight of 610.950 kph set by the Vf 109 V13 recorded as a Bf113R.
The statistics laid out in the book for Me 109 E-3 are:
Takeoff weight minus useful load = 2053kg 4526lbs (including 100kg for pilot, parachute, special clothing, additional equipment, fuel 400ltr oil 29.5 ltr 3000 rnd MG 17 120 rnds MG FF and ballast 25kg)
Max allowed takeoff weight = 2610kg 5754lb
Speed with 30 minute continuous power:
km kph mph
0 460 285.85
1 480 298.25
2 500 310.68
3 520 323.11
4 540 335.54
5 555 344.86
6 555 344.86
7 550 341.75
km min ft
1 1 3,280
3 3 9,842
6 6.3 19,685
9 16 29,527
Service ceiling 10.3km (33,792 ft)
Tightest turn radius at ground level = 125 m = 410 ft
Tightest turn radius at 6km = 230 m = 754 ft
Power Plant DB601A
ground level : 4km altitude
_hp_ rpm ltr/hr
1175 2500 433 1 min increased output
1015 2400 321 5 min increased output
0950 2300 288 30 min increased output
0860 2200 260 Continuous output
_hp_ rpm ltr/hr
1100 2400 318 5 min increased output
1100 2400 318 30 min increased output
1000 2400 283 Continuous output
0975 2250 269 Continuous output economic
Propeller: VDM variable-pitch, three blades, 3.10m diameter