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

[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.

[Robo.]

So basically I was not too far from the truth saying that meeting a E-7 in the BoB was as likely as meeting a Spitfire Mk.Ib 30 vs. 32 pieces and that information is for January.

E-4/Ns also listed in January at 54 pcs, one Gruppe of JG26 used them quite early, that might be cca 40 aircraft in the Summer already (makes sense). I guess Perez's aircraft was part of this Gruppe. It seems that 100 octane fuel and 601N engines were more relevant for Bf 110s Squadrons in the sim. In the actual Battle of Britain, these subtypes were present at rather marginal numbers - at 31.8.1940 we've got 871 Bf 109s in service, let's say some 1é or less % were fighters with DB 601N.

Same with droptanks coming in November - this is very important for next stage of the war (the Blitz as the British call it).

[Kurfürst]

Originally Posted by Robo.

So basically I was not too far from the truth saying that meeting a E-7 in the BoB was as likely as meeting a Spitfire Mk.Ib 30 vs. 32 pieces and that information is for January.

Again, there's E-7 (601Aa) and E-7/N (601N).

Now there was 32 E-7 in the end of August, I agree not very significant, according to the paper they entered service and went on operation just a few days earlier. I think the Ib analogy doesn't stands, it was a single Squadron, and a completely unsuccessful one. Personally I wouldn't mind having it, I just consider it a compete waste of time of developer resources to model a completely useless plane (because of insta-jams). I think Galland's own Gruppe flew the E-4/N and I would bet a leg on it they ranked up quite score during BoB.

Probably because their production just started (none listed as produced as of end of June 1940 yet, so production just started in July or early August). Following that however a total of 186 were produced until the end of October (these would be certainly with 601Aa, again the priority of 601N distribution to 109s did not come into effect until November), so I would expect that in September-October there were fair numbers of them around. Say, 80-90 or more? Pretty much like Mk IIs (was it 5 or seven operational Sqns?).

In any case, I do not see why a Spitfire II, which saw service in similiar numbers and time (1-2 Sqns in August and best, and about half a dozen Sqns by the end of the Battle, is a more justified as an aircraft model than E-4/Ns or E-7s, which at the minimum equipped 2 Gruppen (Six Squadrons), by late August, and probably more in the automn.

The second strenght return list from January only list E-7/N, so its additional to 'normal' E-7.

The absolutely correct historical way would be to model separately an E-4/N (601N) and an E-7 (early 601Aa variant), both were there but in small numbers, say about a hundred or so combined by the late Battle.

What I think would actually make sense and fit into the sim nicely is to model an E-7/N straight away. This is sort of a hybrid but can represent the number of E-4/N and E-7 participating in the battle economically with modelling resources, moreover the E-7/N can be re-usable for 1941 scenarios (North Africa, Malta, Moscow, France 1941), since in 1941 it was the main type and the only 109E type remaning in production, with several hundred produced (ie. all late E-7 seems to have been E-7/N). Its probably being done for the Moscow sim anyway.. and would require little more than a minor change in the external model (pointed spinner, spark plug cooling holes on the cowl, drop tank rack) and FM of existing E-4.

E-4/Ns also listed in January at 54 pcs, one Gruppe of JG26 used them quite early, that might be cca 40 aircraft in the Summer already (makes sense). I guess Perez's aircraft was part of this Gruppe. It seems that 100 octane fuel and 601N engines were more relevant for Bf 110s Squadrons in the sim. In the actual Battle of Britain, these subtypes were present at rather marginal numbers - at 31.8.1940 we've got 871 Bf 109s in service, let's say some 1é or less % were fighters with DB 601N.

Same with droptanks coming in November - this is very important for next stage of the war (the Blitz as the British call it).

Absolutely agree. Its important for the 110s, since about half of them had the 601N, and its a real performance boost for them, being much faster. A BoB sim without 110/Ns is pretty much like a BoB sim without Hurricanes, given their historical force ratios... or +12 boosted variants for that matter.

[Crumpp]

Originally Posted by Glider

I know this is going to sound very obvious but I have always believed that pilots notes were there to help the pilot avoid crashing the aircraft, not an historical document showing the roll out of things like fuel.

Now I know why most of my flying experience was in Gliders, none of the smelly stuff that can catch fire.

It is a fact the RAF did not complete conversion to 100 Octane until around January 1942. That is evident in the Operating Notes.

This is total bull, I would love to see you prove it, why not March 1942, or even have a punt at 1943. Why not 1944 as I know there was a shortage of 100 Octane just before the Invasion, maybe they converted some squadrons back to 87 Octane, they didn't, but what the heck, there is more logic for such a move as there was a shortage then.

Its worth remembering that you still haven't shown us the pilots notes for the Spit I you were quoting as being June 1940. So why on earth should we believe that it was as late as 1942

Glider,

Of course the Operating Notes provide a chronological order to technical changes. We know that technical updates are first published they become supplements to the Operating Notes. It is the operators responsibility to keep the Operating Notes up to date with the latest changes. However, the problem is in dissemination of technical updates. Somebody always does not get the word when updates are published. That is why for major changes like changing fuel a new edition with updates to paragraph 1, Operating Limitations would be published.

Look at all the issues with trying to find a replacement for 100LL in todays fleet!

Technically it was not a quick and easy change over to convert a Merlin from running 87 Octane only to having the ability to use 100 Octane fuel at +12lbs. It involved major modifications and was service level maintenance as noted in the technical order.

This is total bull, I would love to see you prove it, why not March 1942,

No it is true according the Operating Notes. It is a fact. The National Archives probably has multiple copies of the various editions of the Spitfire Mk I Operating Notes.

You can check there to see if an early edition notes changes to paragraph 1, Operating Limitations. Otherwise, January 1942 is the first edition to note 100 Octane is in use for all operational units. If the Operating Notes only mention 100 Octane in Paragraph 7 without changes to paragraph 1, Operating Limitations, then you know the fuel is not being used for all operational aircraft! It is really that simple.