Inaccurate performance data for BOB fighters in COD comparing to RL data

[NZtyphoon]

Originally Posted by Robo.

Ok, rare, but not quite like the Spit Mk.Ib, that was just a funny example (I agree on 1c's insight on Ibs btw). I am not sure about the numbers of the subypes in the second half of the Battle - I certainly didn't know that there were 186 E-7 in October over the Channel area. Fair enough. The numbers are very difficult to prove and often contradicting and complicated with subtypes and post-overhaul conversions. Same with propeller types on Spitfires and Hurricanes in the first half...

Anyone with some good data on the topic?

I agree about working out how many E-7s there were; for example W.Nr 3523 was rebuilt from an E-1 in August 1940, but it did not appear to have had an operational life with any Jagdstaffel until reaching JG5 in early 1942. Do you mean delivered or operational?

Just a quick look through The Battle of Britain Then and Now Vol 5: the first E-7 I can find is W.Nr 2029 of I/LG 2 which was shot down at 4:15 pm on September 11. From memory LG2 was one of the first units to use E-7s?

[whoarmongar]

With two fighters constantly being developed and in service throughout the entire war (the 109 and Spit) with various different models and many intrim variants it seems to me that the date of any scenario is of upmost importance. It appears some people like to "stretch" the date of the BoB so as to include the latest variant, more potent model of their favorite fighter.
Personally I dont see a place for the cannon Spit in the BoB. However if it were implemented into CoD I dont think the reliability of the cannon would be an issue as it was caused by icing at high altitude and CoD Spitfires never reach high altitude.

[winny]

Originally Posted by whoarmongar

With two fighters constantly being developed and in service throughout the entire war (the 109 and Spit) with various different models and many intrim variants it seems to me that the date of any scenario is of upmost importance. It appears some people like to "stretch" the date of the BoB so as to include the latest variant, more potent model of their favorite fighter.
Personally I dont see a place for the cannon Spit in the BoB. However if it were implemented into CoD I dont think the reliability of the cannon would be an issue as it was caused by icing at high altitude and CoD Spitfires never reach high altitude.

The cannon jammed because due to the thinness of the wing it was mounted on its side, not because of altitude. It was a problem with the ejection of spent cartridges, they simply wouldn't clear properly. They were withdrawn and didn't re- appear until November.

Edit: a little more info on mkIB. First one delivered to 19 squadron on 27 th June serial number R6761.
Armourer Fred Roberts explained " most of the trouble stemmed from the cannons being mounted on their sides, the empty shell cases therefore being ejected sideways from the breach and being deflected back into it. The nose of the shell dropping slightly and striking the breach end of the barrel, buckling the the shell case at the neck caused another kind of stoppage. We fitted various kinds of deflector plates. We altered the angle of the plates, fitted rubber pads to dampen the force of the shell case, but none of these experiments worked. We also had magazine feed troubles, caused by it lying on it's side. To counter this we tried varying the tension applied to the magazine spring but that was unsuccessful".

[Robo.]

Originally Posted by whoarmongar

It appears some people like to "stretch" the date of the BoB so as to include the latest variant, more potent model of their favorite fighter.

Yes, very much so. But if what they say is true and 186 E-7s with 601N engine were present in the Channel area in the last month of the BoB (October), then it should be in the game, too.

My comparsion to the Mk.Ib was only ironical as with 30 made examples, I believed this is pretty much comparable to couple of dozens of German E-7 that actually took part in the battle in September / October. If it was more, I take it back.

As for Ib - not important, but I remember reading about the unsuccesful trials and frustration of the pilots when the cannons malfunctioned. The Squad Leader demanded MG Spitfires back to much unliking of his 'boss' at MoD, and the Squadron got them back eventually - but they were not new Mk.IIs but beaten up Mk.Is with old de Havilland propellers (not sure about names and details I am afraid)

[whoarmongar]

Ah my altitude remark was a bit tongue in cheek. Sometimes I just cant help myself.

[winny]

Just another quick P.S about the first cannon armed Spitfires.

They didn't have machine guns. Just 2 hispanos.

The ones with the Mg's didn't appear till 11th August, the first one being S/No X4231

They changeover back to the 8 mg version was completed on 4th September by using "some clapped out old things from an OTU" according to Squadron Leader Pinkham, who had campaigned to get the Ib's replaced.

Ironically he was killed in one of these "clapped out" machines the very next day.

[Kurfürst]

Originally Posted by Robo.

But if what they say is true and 186 E-7s with 601N engine were present in the Channel area in the last month of the BoB (October), then it should be in the game, too.

I think this need to be clarified a bit - the 186 E-7 delivered means that this much was produced as 'new builds', or Neubau by factories (as opposed to conversion of existing airframes, so conversions are not included in this number). These aircraft went to storage at first, as normal, and a number - not all of them - was issued to the the frontline units as needed.

E-7 had two engines mounted: DB 601Aa (so performance was same as E-4 but more importantly, the E-7 could carry a droptank and boost its range to 1300 km) and 601N. In the latter case its designation is E-7/N. I think its evident that all the early E-7 had 601Aa (since 110s had priority first for this engine and 109s had received priority only in October 1940), the one in the late automn/winter/spring 1941 had the 601N, and a performance between the 109E and F, roughly 590-595 km/h top speed. A number were produced in 1941 as E-7/Z, meaning 601N engine plus GM-1 boost.

I think its interesting to see the production of 109 aircraft in the BoB period (July - October 1940, as the British define it):

New airframes were delivered in the following number (not including conversions). Previous production is thus not inlcuded, just the number produced in the above period.

E-1: 55
E-1/B: 110
Total E-1 variants: 165

E-3a: 75 (export version)

E-4: 47
E-4/N: 20
E-4/B: 211
E-4/BN: 15
Total E-4 variants: 293

E-7: 186

F-1: 9

Total Bf 109: 728

So as a matter of fact the E-7 is the 2nd most produced variant of the BoB period.

[Robo.]

Oh, good info. It would be helpful to have a list of aircraft types actually present during the months of the BoB. I am aware that the number is just Neubaus and that only part of the new machines were assigned to the units in the Channel area. Same with E-1s being more common at the early stage - I suppose your list does not include pre BoB production of this subtype.

I agree it's nearly impossible to get the precise data with the amount of conversions and engine variants.

[NZtyphoon]

I'm pretty sure that the E-7/N could be distinguished from the E-7 by a small reverse D-shaped air intake in front of the exhaust fairings. This photo is of an E-7/N flown by Oblt. Joachim Müncheberg of 7/JG26 based on Sicily in Feb - late March 1941; the air intake can be seen behind the spinner.

[Kurfürst]

Originally Posted by Robo.

Oh, good info. It would be helpful to have a list of aircraft types actually present during the months of the BoB. I am aware that the number is just Neubaus and that only part of the new machines were assigned to the units in the Channel area. Same with E-1s being more common at the early stage - I suppose your list does not include pre BoB production of this subtype.

I agree it's nearly impossible to get the precise data with the amount of conversions and engine variants.

I only have detailed subtype breakdown for 31 August.

On 31 August 1940, fighter units (excluding JG 77) reported 375 E-1s, 125 E-3s, 339 E-4s and 32 E-7s on strength, indicating that most of the E-3s had been already converted to E-4 standard. By July, one Gruppe (Wing) of JG 26 was equipped with the Bf 109 E-4/N model of improved performance, powered by the new DB 601N engine using 100 octane aviation fuel.

As of 1 January 1941, the following 109 / N (DB 601N) subtypes were in service:

Bf 109E-1 : 16 pcs,
Bf 109E-3 : 1 pc,
Bf 109E-4 : 54 pcs,
Bf 109E-6 : 1 pc,
Bf 109E-7 : 34 pcs,
Bf 109E-8 : 2pcs.
Bf 109F-1 : 5 pcs.

Total 112 Bf 109E with DB 601N present in service, plus 5 Bf 109F.

Hooton gives lost % for the subtypes, which confirms that most E-3s were converted into E-4s (a small change in the internal of the MG FF to fire Mineshells, nevertheless the German designation system for a subtype changes when a change was done to radios, guns or engine or similar important internal). By August E-3 loss % were single digit, new-born E-4 losses increased accordingly. E-1 accounted to about 35-40%, E-4 to about 60% and E-7 were the rest.

Indeed conversions can make it difficult, as most early /N conversions were in the field, and by November droptanks were retrofitted. See attached picture of a JG 53 E-1. Given the simplicity of the 109 droptank installation (essentially a rack and compressed air lines from the supercharger, and a fuel line feeding the droptank into the main tank, no fuel pumps etc. involved) I guess most of the latter was made in the field as well.