Small case study: Bf 109 D vs. French fighters
 

The Jumo-engined Bf 109 D was still used by some Luftwaffe day fighter units during the so-called Phoney War period 3.9.1939 - 9.5.1940 (and not to mention night fighter units operating the Bf 109 D also in daylight). The common wisdom is that the "Dora" was obsolete/inferior against modern Allied fighters by 1939 but the official German combat records claim that the Dora´s score against encountered modern French fighters was actually little better than 1:1. So far I have not found any info if Dora´s encountered any Hurricanes (or Spitfires).

Michael Ziefle 2011 (Die Messerschmitt Bf 109 B/C/D, s. 95-96) states that the "Dora" equipped units JGr 152, JGr 172, JGr 102 were credited with 8 destroyed French fighters (5 Morane 406 + 3 Hawk 75) against the loss of 8 Doras in air combat (of which 7 to French fighters).

I have compared these records with two books covering the combat history of Morane 406 and Hawk 75 in French service (Stenman - Ehrengardt 2014: Morane MS 406 Aces + Persyn - Stenman - Thomas 2009: P-36 Hawk Aces of World War 2). The picture is somewhat confusing when one compares data given in mentioned books:

On 24.9.1939 at 13.00 hours (German time) near Saarbrücken the Morane-equipped GC I/3 clashed with the Doras of JGr 152 - the actual losses seem to have been 2 Moranes and 2 Doras although there is some difference in loss accounts: French were credited with two air-to-air victories while German records claim that one Bf 109 D (Lt. Rosenkratz) was lost in mid-air collision with unidentified plane, which might have been the other Bf 109 D (Gefr. Hesselbach) lost in the same combat. The JGr 152 claimed as many as 5 Moranes destroyed in this combat, but Ziefle downgrades that to three Moranes confirmed as destroyed. Ziefle mentions that JGr 152´s Doras were involved in another air combat against Hawk 75´s later on the same day - so it migh be that the "5 destroyed Moranes" consists of following: 2 actually destroyed, one German-confirmed overclaim (Ziefle´s claim) and two Hawk 75´s confusingly claimed as "Moranes"? (see the following).

Quite confusing air combat occurred on the same day of 24.9.1939 about 15.00 (German hour) in which "Doras" of JGr 152 were again involved together with Bf 109 E´s of II/JG 52. The enemy unit was GC II/4 equipped with Hawk 75. According to Persyn the Hawk pilots of GC II/4 pilots shot down three Bf 109 D´s of JGr 152 in this combat - he does not mention French losses. However German records (cited by Ziefle) do not confirm French claims but instead state that JGr 152 pilots were victorious shooting down two Hawks with the price of having two "Doras" damaged (repairable 30-40 %). Other Dora-equipped Luftwaffe units did not claim and did not record any losses on the 24.9.1939. In the light of contradictory info one wonders what might have been the actual score on this combat and what were the actual air combat losses of both sides on 24.9.1939?

On 25.9.1939 JGr 102 (ZG 2) pilot Erich Groth flying Dora claimed one Hawk 75 but it was not confirmed by Luftwaffe.

On 27.9.1939 one Dora of JGr 152 was lost - but not to enemy fighters but to the return fire of Fairey Battle (103 Squadron).

On 30.9.1939 at 16.45 the Doras of 2./JGr 152 (together with "Emils" of JG 53) were involved in combat against Hawk 75´s of GC I/5 and II/5. In this combat JGr 152 pilot Olt. Liensberger was credited with one destroyed Hawk. No Bf 109 D´s were lost on 30.9.1939 but German sources (Ziefle) confirm as many as four "Emils" of JG 53 being lost to French fighters during the air combats of 30.9.1939 (one against Morane-equipped GC III/3 and three against Hawk-equipped GC I/5 and GC II/5) - however the Emils of JG 53 were credited with three Hawks, one Morane, one Mureau 117 and one "Caudron 710" destroyed on 30.9.1939. Persyn and Ehrengardt do not mention French losses on 30.9.1939.

On 6.11.1939 occurred the famous air battle which by its results seemed to prove that the Dora was obsolete against Hawk 75. Despite superior numbers and initial altitude advantage the JGr 102 lost four Bf 109 D´s in combat against the Hawk 75´s of GC II/5. French pilots were credited with five destroyed Doras without losing any of their own planes (AFAIK) - this seems to match well with official German losses (four planes destroyed in combat and one forcelanded suffering unrepairable 70 %). Although Bf 109 D was not as agile in dogfight as Hawk 75 it seems that the losses were more due to tactical errors of the pilots of JGr 102: they went in dogfight with less nimble planes adopting wrong tactics and their coordination in combat was poor. Probably there were also some overconfidence/attitude problems by JGr 102 pilots because of many easy air victories gained during the Polish Campaign (Hawk 75 was tougher opponent than anything that they had encountered in Poland).

When it comes to technical comparison of Bf 109 D vs. Hawk 75/Morane 406 one should take in account that the so-called "factory values" are overoptimistic theoretical numbers of manufacturers and may reflect only ideal test-results with planes without paint, armament and other combat load. For example 500 km/h is often given as top speed of Hawk 75 but it is far too optimistic when compared to actual test flight results made with operational planes. See: http://forum.warthunder.com/index.ph...-75-top-speed/

Re: Small case study: Bf 109 D vs. French fighters
 

GG

With all resepect to the authors of the books you checked, but maybe they don't make any claim to be complete with regard to day to day battles during the Phoney War?

For the German/French side you need to check books like Prien's Die JFV der Luftwaffe vol 2 and Cornwells Battle of France then and now and also Shores' Fledgling Eagles.

If you do you will get a much more complete picture.

Cheers
stig

Re: Small case study: Bf 109 D vs. French fighters
 

For a thorough account from the French side I suggest Jacqueline and Paul Martin's "Ils etaient La" (They were there..."), though I would expect the details to have been integrated into the later Cornwell book.

Re: Small case study: Bf 109 D vs. French fighters
 

Thanks for your respect towards the authors (including me). I
wrote "Morane aces" for Osprey with references to the books that are mentionned here: "Fledgling Eagles" (I am a co-author - French edition: "Les Aiglons"), "Ils étaient là..." (I was the publisher), which much inspired Peter Cornwell to say the least, and also Persyn/Stenman's Osprey and Prien's volume on the PW.
It seems difficult to have a broader picture.

Re: Small case study: Bf 109 D vs. French fighters
 

Indeed very interesting topic. According to my research JGr.152 fought two times: at appr. 11 & 13 hours. As I remember 15-16 hours was mentioned by Shores first and apparently this story is completely wrong. But maybe someone knows more about?

Re: Small case study: Bf 109 D vs. French fighters
 

Prien in JfV Teil 2 has five claims on this date for Ms 406 and two JGr. 152 100% losses and two damaged (30-40%). Coincidence, one (maybe 2) of these claims for Lt. Willi Elstermann.

In September and October 1939 both the Curtiss Hawk and the MS 406 fighters (800 hp engine) still held the edge over the Me 109 Ds (700 hp engine) they met. The 6 November combat was even discussed in the French Parliament and celebrated in the French media as the battle of the « the 9 vs. the 27 ». I read somewhere (a French source?) that the Bf 109 Doras of JGr. 102 were led that day by the leading Luftwaffe ace at the time, Maj. Hannes Gentzen but that would appear not to be the case. From November 1939 onwards the Luftwaffe introduced the Emil variant of the Bf 109 (1,000-1,100 hp engine with the advantage of fuel injection), which was clearly better in the air and immediately worried the French.

Re: Small case study: Bf 109 D vs. French fighters
 

One should also remember that speed numbers can vary +/-3 % from factory numbers. Wear and tear on operational machines will cause a decrease from factory numbers.

I don't know about the French but the USAAF did their own testing of a/c and they had better match or exceed the manufacturers claims.

Re: Small case study: Bf 109 D vs. French fighters
 

The French did their own testing, and like the Brits, did not came close to the performances claimed by the US aircraft manufacturers. The tests are evoked in Lionel Persyn's "Les Curtiss H-75 de l'armée de l'Air"