Bf109 test data
 

GUYS! PLEASE don't turn this thread into an ego/red/blue argument fest. I just want links to historical data.

I have been unable to decide which data to use for Bf109 testing (speed at altitudes, climb, turn).

There seem to be factory specs, French Tests, British Tests, Swiss Tests but there does not appear to be a definitive data set for any "BoB" 109.

Would you please post a link to historical data that you believe best represents (one of?) the 109s we have so that I can test ours. Please confirm Manifold Pressure, RPM, Radiator setting and anything else you believe is relevant so that I do not rely on my interpretation alone.

Again, I don't want 'opinions' just data and any qualifying information.


MODERATORS. Please leave this on the open forum for a week or so, so that it is seen by as many as possible. We can move it to FM/DM forum later. Also please moderate the thread heavily to leave only constructive posts.

Many thanks.

http://www.wwiiaircraftperformance.o...09/me109e.html

http://www.spitfireperformance.com/spit1vrs109e.html

http://www.wwiiaircraftperformance.o...109E1-1791.jpg

http://www.wwiiaircraftperformance.o...109e3-1792.jpg

Dont think you find any better

whatever source you choose there will be another saying different, so if you have the time take as many believable sources as you can find and use the average values

Thanks, I don't know how I missed the first one. It seems to collect everyone's opinions :)

Still not sure which to choose so I think I'll start with the Me109E-3 and see how that looks against a selection of them.

I'd also recommend Kurfürsts site, which provides some more in depth information on some of the data found.

Salute

Nothing is ever simple, there are no easy ways to arrive at 109 performance figures which are 'exact'.

The German figures are qualified with a note that different engines of the same type, (DB601A, N, etc.) can vary from +2.5/-2.5 percentage difference in engine horsepower output. That can easily add up to 20 kilometers per hour difference between different aircraft when we are talking about top speed at altitude.

The British, American and Swiss figures are done with aircraft which are either captured or export variants, which might or might not perform up to German standards.

In addition, often tests are done at different boost levels, or with radiators either open or shut.

Some of the German documents may or may not have figures which are inflated, as they are intended to provide information for potential foreign buyers, and obviously a higher performance aircraft is more likely to sell.

All of the above means that one has to be VERY careful in the study of the various tests/figures, and not jump to hasty conclusions.

What we do know is that the 109E was a very competitive and dangerous aircraft, capable of taking on the Hurricane and Spitfire in the aerial combat arena. And vice versa.

A good selection on the WWII aircraft performance site. Interesting comment on items 13 and 14 ... the ones with 500Kmh IAS at sea level.

Thanks for your inputs guys.

IvanK I am disregarding items 13 and 14 as they have no 'provenance', i.e. no acknowledged testing organisation although the speed test is close to the V15a tests so they are possibly based on a prototype perhaps simplified for publication.

For interim information: I am testing the 109E-3 at 1.3ata and 2400rpm, radiator 1/4 open which aligns with the Swiss tests which are very close to the handbokk figures until 5,000m where they fall away more than the handbook. The French tests at 1.3ata 2400rpm produced better results to 4,000m but it was probably an E-1 and curiously the radiator was open to 4,000m due to cooling problems. The average of all the six data sets I have is quite close to the handbook, 2%-3% above handbook at low altitude and matching the handbook in the 4,000m to 7,000m region. In any case, the CoD 109E-3 is below all those figures and is looking like 93-95% of handbook figures at altitudes to 1,500m and around 98% at 5,000m. I still have more tests to do at other altitudes.

Of course I don't know if the various figures are supposed to be max speeds or just representave performance at those power settings so I don't know of we can compare them with Spitfire Max Speeds. We can at least see if CoD 109s are perfoming near to those historical tests - or not.

I'll post results here when I finish.

Interesting Klem..thanks for yer hard work

I.

The Me 109E had at least four fitting and used during the Battle of Britain, with different boost and outputs.


1. The DB 601A-1 with the old type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4000m.

2. The DB 601A-1 with the new type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4500m.

http://kurfurst.org/Engine/DB60x/datasheets/601a1.jpg


3. The DB 601Aa with the old type supercharger, 1.35 ata for five min and 1045 PS, and 1.45 ata for 1 min and 1175 PS. Rated altitude being 3700m (altitude output was otherwise very much like the DB 601A-1 / old s/c, though it is an open question wheter the new s/c was fitted to the Aa as well. So far no evidence to that though.)
This is the type we have in the sim.

http://kurfurst.org/Engine/DB60x/datasheets/601Aa.jpg

4. The DB 601N, 1.35 ata for five min and 1175 PS. Rated altitude being 4800m. (there was a second type of 601N, mounted in one in the 109F had better supercharger and IIRC 5200 m rated altitude)

http://kurfurst.org/Engine/DB60x/dat.../601N_Emil.jpg

II.

Therefore, it is pointless to compare our 601Aa equipped Emils performance (1.35ata) to real life tests of DB 601A-1 equipped Emils at 1.3ata. It makes about as much sense as checking Spitfire I performance from the crayon +12 boost graph :D to actual tests of serial production +6 1/4 boost tests.

It should of course match the real life DB 601Aa at 1.35ata (V-15a, Baubeschreibung "5%" specs, Swiss trials of serial no. 2404 - these all have Aa, although it's quite clear the Swiss graph is only showing high speed supercharger, ie. Hohenlader performance - note the almost exact match between V15a Hohenlader and the Swiss single speed graph)

http://i38.photobucket.com/albums/e1...psd822ce28.jpg

III.

Misc. comments

1. The "French 109" was an E-3, not an E-1: WNr. 1304. Besides the aerodynamic differences between the E-1 and E-3 are marginal, probably in the order of 1-2 kph. It seems to loose manifold pressure continously with altitude - I suppose the use of French lubrication of oils instead of German synthetics may be at culprit (since the hydraulic coupling was using this oil). It had a DB 601A-1 and operated at 1,3ata, ie. lower boost/power than our E-1/E-3/E-4s.

2.

The WNr. 1791 and 1792 tests can be easily forgotten given that
- this was never a performance tests, but a speed comparison with various fittings: As it notes clearly - Geschwinigkeitsunterscheid - comparison of speed

-as a result only the relative values (guns in / out, slats sealed/not sealed) were interesting Mtt AG in these tests, they were not made to get absolute values.

- they do not have the same 1.35ata Aa engine as our Bf 109E has, but a weaker 601A at 1.3ata, which developed about 55 HP less.

- in addition report clearly notes the engine outputs were not corrected for guaranteed engine performance, which means we/they have no idea how much those engines were developing. Again, given that all those two reports were supposed to show was what's the speed difference with this thing on and that thing off this hardly concerned Mtt at the time.

3. The fact that Mtt. accepted the V15a trial results and guaranteed them within 5% for the ca. 4000 Emils produced needs very little comment.

4. The "nazi propaganda" (pathethic, even for Mike :D ) aka 500 kph curves for the 109E w. DB 601Aa (confirmable from engine specs) come from Bf 109 E Baubeschreibung, Chapter V. Leistungsblatter (Performance sheets), from 1939.

It's one chapter from a 75 page document describing the airframe, powerplant, equipment, armament, performance, as well as the all the instruments.

It's hardlly a two page "marketing material" as some like to pretend - besides the fact that the specs are guaranteed and are based on flight tests.

OK, I understand but have a couple of questions.

Swiss test: You seem to use the 'Original VDM' curve. I don't know what the other curves represent so can you please explain? I picked up somewhere that the test was at 1.35ata. Can you find a source for that?

V15a: This was conducted at 1.31ata at low level and 1.3ata above 3,300m. How can I reproduce that in CoD? (I don't usually fly the 109).

How can we be sure which 109 engines are supposed to be modelled in CoD (or which should be)?

What configuration does the "Handbook" represent?

EDIT: I can't seem to find weights of the Swiss and V15a aircraft. Also, was the V15a version a fully loaded military configuration?

Thanks,

The Swiss test is a comparison of various propellers and the original VDM (German) produced propeller. 1,35ata is coming from the fact that the engine is listed as the "Aa" type, and that the test is run at "Vollgas" - literally full throttle (not the 1-min WEP though), which is 1,35ata for the Aa.

Other than that, sadly I do not have the rest of this report, and I would be glad if someone has it.

The answer is that you probably should not - V15a was tested (actually two test runs - one clocked for low altitude on four way course, the other at different course at high altitude after insturment calibration) while running below the nominal boost pressure (1,35) and the results were re-calculated for that nominal boost (that's the slightly displaced higher spec line).

1.35ata in game is a clear indication of the Aa, and IIRC the game's engine related files also show Aa specs.

What should be is a different question - any of the above engines in fact, but I guess 1C had to choose the one which they had the best documentation for. Ideally we would have a gazillion Emil types with similiar chaos as with Rotol, DH, 87 and 100 octane Spits and Hurries.. but it's impossible to tell how many had A-1 old, A-1 new s/c, or Aa, apart from that Aa amounted to about 1/3 of all 601 production

We can tell the number of Ns, because they were relatively rare..

Bottomline is, since we have Aa variant, we should have the Aa specs. The Aa is a bit better at low altitude (ca. +50 PS), an A-1 with the new supercharger is better at high altitude (ca. +50 PS again).

If you mean the complex graphs with landing take off distance times etc., I guess it's a 'generic' 109E. I am pretty sure that performance difference between E-1 and E-3 were marginal. They were exactly the same, even the wing was the same, expect for a bulge for the cannon on the E-3 and that the cannon was put into the other wing weapon bay than the E-1. They could be rather easily converted.

Engine is certainly 601A-1, probably early one. Problem is the engine ratings are not shown, and in these kind of papers it was quite common to use 30-min (1.2x-ish ata) ratings instead of full power. IIRC comparison of the Handbook with RAE's testing of the "French 109E(-3)" point strongly to that the handbook indeed shows 30 min performance only and not the full ratings.

No idea on the Swiss aircraft. I don't have the full report and it seems nobody does.

The V15a weights are unknown, although it's noted that the aircraft is serial production form, with 4 MGs installed. Exhaust covers were missing and the engine cowling was 'raw' (I suppose this means unpainted), the rest of the aircraft had standard camoflage. the s/c inlet was squarish and looks very much like the standard one on the Emil; they expected that a rounded intake would work better (as we know this waited until the 109F). All in all Mtt expected further improvements in performance with these added. Ammo may or may not be installed, or ballasted, but in any case, a few dozen kgs in or out has next to no effect of a fighter's top speed. Landing gear retracted, tailwheel out. radio antenne.

All in all it was pretty much the stock (DB 601Aa powered) E-1 in every way.

Your welcome. ;)

OK, thanks. I'll keep the V15a, Swiss and Handbook curves only and plot the CoD 109E-3 against them.

I'll start the tests again at 1.35ata, 2400rpm, 1/4 radiator.

I guess we don't have access to the manual 2-speed gearing, perhaps its automatic. That might account for the strangely shifting plot I got first time but... I'll start again.

sorry, if..., but what you can tell about soviet trials of emil? 440 km/h at SL (5 min 1.35 ata (980mm))...

I don't think that the supercharger speed could be set from the cocpit. However the system could certainly be. Supercharger speed on the 601 was regulated by two oil pumps. The amount of oil in the sytem decided oil pressure, and thus the amount of slip, and so supercharger speed.

One pump supplied oil at a constant rate. That's essentially a fixed speed, that's why the DB power curve near SL is a straight line.

The second pump supplied oil at a variable rate. The rate was decided by a barometer (increasing with altitude). It did not operate at all until about 1.5 - 2 km, this is where the "smooth" power curve typical of DB engines begin.

If you switch this second pump off, you essentially have the low speed gear (Bodenlader, the Brits used MS gear for that term).

If you set this to deliver maximum amount of oil, the supercharger will run at max speed at all altitudes, it's essentially like a 2nd or high altitude gear (Hohenlader), exactly as on a two speed Merlin's FS gear. Naturally like the previous, it will develop less power at low altitude, hence lower speeds will be achieved (since running the s/c at full robs the engine of power, and there's a large loss power from increased charge temperatures).

A couple of later tests (i.e. Rechlin G-6 curves) show this was used sometimes, I believe because setting up the supercharger to minimum/maximum speed like that ensured that irregularities with the hydraulic coupling and supercharger speed did not interfere with accurate measurements, and SL speed and rated alt. speed could be easily measured. The interim was easy to interpolate, given the engine curves.

I pretty sure the same was followed by the Swiss and possible the "Handbook" test (which I believe may possibly replicate a rechlin trial's result). The US tests were quite clearly done this way, too.

Otherwise Quite simply no amount of drag or power difference between individual planes can explain no less than 40 kph top speed at low levels, while high altitude speed is pretty much the same in all tests. That alone rules out DRAG differences, since those would show up at all altitude, so it's NOT any perceived difference between the V15a 'prototype'

Propeller was the same as the serial type, it's clear from V15a papers.

That leaves POWER. To have such huge differences in speed, the power differences have to be present only at low altitudes, and has to amount to a massive scale, like 100-150 horsepower less. There was simply no such individual difference between production engines.

And here's the problem. V15a's engine was bench tested, which shatters any speculation about how the supercharger worked or not. They measured about 1015 PS in flight, which is the similar to the normal production output of the 601A series. That 1015 PS is the same power wheter it's a pre-production or production engine, or if Willy trained squirrels to drive the propeller.

There was, however, such huge difference between the high/low supercharger gears of the DB 601A.

They are very, very low near SL, but I think if you look at the climb curves of the same plane (which is VERY power sensitive, and abnormally low/increasing steeply) you will realize that there was something very wrong with the engine at low altitudes (my guess is a badly set up supercharger or mixture).

Then you are ignoring the other relevant material in favour only of what Kurfurst is advocating. Who has a point of view. Which may or may not be accurate...

That is not to say that I don't think the 109E-3/E-4 as currently constituted are too slow in CoD, (although proportionately MUCH better modelled than the Spitfire and Hurricane), they are likely too slow, however...

One, you should be aware the designation 'V15', indicates a pre-production, test aircraft, which may or may not include the standard loadout or equipment of the production version, this is not an E-3 or E4 or even an E-1, and this cannot be considered a test of a standard factory variant, it was done in 1938, before the E-3 was in production and before the tests done of the standard variants.

For example, a later 1939 test of an actual German production 109E3 to determine the loss of speed as a result of the fitting of wing guns shows a top speed at sea level of 467 km/hr, less than shown with the V15 variant. The E-3 test was done at 1.3 ata, not full 1.4 boost, so the speed would be higher at a higher boost, with the additional 100 PS that would give, but it is hard not to accept the document is more relevant than the V15 document. Tests of the existing game 109E3 should see a speed of 467 km/hr at 1.3 ata, something which I believe it fails to achieve.

http://imageshack.us/a/img222/4608/me109e31792.jpg

Two, in reference to another example, the Swiss tests, indications are the DB601Aa engine was an export only variant. And many facts bear this out. For example, none of the aircraft captured during the BoB had the Aa version of the DB-601 engine.

And the German manual for the DB601A or B, which includes many of the charts seen on the WWII site and Kurfurst's site, and which is dated on issuance October of 1940, with extensions, has no reference to the DB601Aa. It can be downloaded here:

http://www.scribd.com/doc/32387854/Handbuch-DB-601-A-B

The DB601A/B engine was listed at 1100 PS at sea level, but that actually wasn't it's highest output point, that was at approximately 1.7 thousand meters, when it outputted approx. 1170 PS.

A translated captured German document which agrees with the suggestion no DB601Aa were used in the Luftwaffe aircraft is a bulletin the Germans themselves issued in November of 1940 allowing engine rpm to be increased over a certain altitude, and the only engines mentioned were the DB-601A or B and N.

http://imageshack.us/a/img837/4093/d...cresenov40.png

In any case, dismissing the results of the British and French tests as irrelevant is not necessarily the correct choice as there is very detailed information provided there which can shed light on the 109E's performance. And for example, the British Rolls Royce tests tend to agree with the test of the E-3 I have shown above.

Messers Rolls Royce did their speed and climb tests of a captured 109E-3 at 1.23 ata, the 30 minute limit boost level, and achieved a speed of 285 mph/456 km/hr at sea level at that boost. Obviously top speed at 1.3 and 1.4 ata would be higher, but you can see a linkage with the German E-3 test at sea level.

http://www.wwiiaircraftperformance.o...-speed-rae.jpg

So as I posted before, careful consideration of ALL the facts is important when coming to a conclusion re. performance.

Buzzsaw - You're mixing something here. The export thingy was the Bf 109 E-3a (in which the a denotes the export use). The Romanians received the same type as did the Japanese (the latter for tests). I have the full Bf 109 E manual compendium from Luftfahrtarchiv Hafner (reproduced originals) and the DB 601Aa is listed as engine type.

BTW you accuse Kurfürst of " a viewpoint". If I were you I'd be very quiet since you obviously represent the other side of that particular medal. :-|

The 'a' is not necessarily for export, there seems to be lots of confusion regarding that.

Buzzsaw is certainly making a good point. The FTH of all 109s in game is 4500m, suggesting that DB 601A-1 version is modelled.

467 kph at S/L at 1.3 ata seem very reasonable (water cooler 3/4 closed). The test were not recalculated for engine's guaranteed power yet.

According to the DB601A manual 1.4 boost was for take-off only ("am Boden bei Abflug"). The highest boost mentioned for flying at ground level ("in Bodennähe") is 1.3 boost.

http://i50.tinypic.com/zsvi3k.jpg

There is nothing preventing the pilot from using this boost during combat at ground level. However there is no evidence at all that this boost was authorized or even used against regulations (e.g. pilot anecdote) for any other condition than take-off. Of course power and speed can be higher if the engine is mistreated, but this incorrect handling should not be considered during performance dicussions and should actually be penalized by the game.

OK Guys, thanks.

We don't seem to have a problem with the historical performance curves, only the particular engine in use.

My memory, as ever, being a little unreliable I had forgtten a book I have tucked away called Bf109 by William Green. I found it last night and he talks about the V series including V15 which had the DB601A engine and in the same sentence says "this was the engine variant used by virtually all Me109s for the first 18 months of the war." But I guess that will only fan the flames.

None of which solves the argument unless someone has production/installation figures for the A and Aa which might lead us to a decision. Even that would no doubt be contentious as I imagine there could be a case for both engines.

SO, I am going to separate the issues. I'll test at 1.3ata AND 1.35ata with 2400rpm and 1/4 radiator and put back ALL of the curves I had in the beginning. This will:
1. Tell us what CoD 109E-3 is doing (my main aim)
2. Let everyone else return separately to the bun-fight over what we should be getting.
3. Raise the question "what do 1CMG think they are giving us".

And 3. is the real point for those that disagree. That's where the A and Aa camps should be directing their energies.

DB 601Aa
 

From TOCH. Very interesting posts there btw, I won't post all, but you can follow the link.

http://forum.12oclockhigh.net/showth...6932#post26932

OK, my bad. I forgot I had abook called Bf109 by William Green. In it he covers he entire development of the 109 and of V15 he says it was fitted wwith the DB601A and goes on to say that "this was the engine that powered virtually every Bf109 for the first eighteen months of the war". Yes, I know that's contentious.

More memory problems, I forgot the 1C Manual for CoD which gives us the following max figures:

Take-off
Initial climb at 250 km/h.
Raise gear.
Raise landing flaps and adjust trim accordingly.
Max 2,468 rpm / 1.45 ATA

Climb
Max continuous 2,368 rpm / 1.35 ATA.
Oil temperature: 30 to 75 C, up to 95 in short bursts.
Water temperature: 80 C, up to 105 in short bursts.

Cruise
Max 2,326 rpm / 1.20 ATA.

The DB601A max figures for these are 1.4, 1.3 and 1.15 so it seems 1C have given us the DB601Aa (whether everyone likes it or not).

However 1C also give us 460kph at SL and 560kph at 5,000m.

Looking at the available figures again.....

V15 with the DB601A gave 485kph at SL on 1.31ata corrected to 498 for guaranteed engine performance and 561/4900m on 1.33ata corrected to 572/4800m. But did this represent a standard military loaded aircraft in 1938? It compares very favourable with J-347s DB601Aa 'true' performance a full 20 months later. Is this likely?

Me109E-3 J-347 ("The Swiss Tests") with DB601Aa gave 464kph at SL and 565kph at 5000m.

E-1 1791 and E-3 1792 both with DB601A gave 475-476 at SL on 1.3ata (max 5 mins) and "These speeds are on normal temperature and right boost pressure regulator setting, nevertheless, not on guarantee achievement of the engine". This begs the question on two separate aircraft "why not?" and leaves the door open to speculation that the guaranteed engine figures were not being achieved. Although without corrections the SL figures aren't that far below V15 (uncorrected for guaranteed performance and therefore in the same circumstances as 1791/1792) and which used fractionally higher boost.

The Bf109E-? curves for 16th December 1939 give 462 at SL and 562 at 4500m, presumably at the max 5 min contiuous rating... but for the 601A or 601Aa?? I am assuming the 601A because of the date and the fact that it is from the handbook.

Bf109E-3 French tests (DB601A) gives us about 475-480kph at SL and 550kph at 5000m.

Bf109E-3 US tests (engine unknown) give us 467kph at SL and 543klph at 5000m.

I realise I am going around the same circles as several other people and I am forced to the conclusion that 1C MG are modelling the Bf109E-3 on the DB601Aa and the Swiss Tests. The boost figures 1C give us are for the DB601Aa which the Swiss a/c had and the speed chart 1C give us for CoD closely resembles the Swiss results.

Whether they should be doing that is open to question. I have no idea when the DB601Aa was introduced and in what numbers.

I'm also inclined to disregard the V15 figures because everything else is against them including their date, the fact that it was a dev a/c (although at pre-production status) and full details of the aircraft loadout. Unfortunatley the only set of DB601Aa figures seems to be the Swiss tests.

Anyway, I'll do the 1.3ata and 1.35 ata tests and show them with the various data above. It will at least tell us if 1C are achieving what they say in their manual and I'll leave to to you guys to fight over which variant(s) should be in the game.

Hi Klem, as you have seen there is no getting around the bunfight of choosing which tests to regard! I agree that as we have the DB601Aa in CloD, we may as well use the Swiss tests, which are pretty consistent with the rest of the flight test data anyway. I expect that Kurfust might present his opinion that the SL performance in this test is low because the supercharger was locked into high altitude gear. Myself I believe this is unlikely, and there is no documentation supporting such usage (just the possibility it could occur).

This is quite interesting...from Steinhilper, we know that 109 pilots tried revving their DB601 over limits to gain extra boost around FTH, which was only approved subsequently. If the 1.4 or 1.45ata clockwork boost worked at any altitude, surely it would have been used. It is intriguing that no anecdotes or reports exist!

camber

I would say that what we have in ClOD is a mix of A-1 and Aa qualities, e.g. fth od this 601 is 4,5 km, yet the mfp at SL is 1.45 ata (with Erhoehte Notleistung).

The weird and unlimited 'afterburner' usage is also pretty much fictional and so is the drop of ata unless you drop the pitch under 2200 U/min.

I have seen the actual FM files somewher on this forum and iirc it said A-1 so I assume that is what 1c tried to model.

My test showed that E-3/E-4 in CLoD reached at sea level:

- 1.35 Ata 2400 RPMs - 450 kph
- 1.45 Ata 2400 RPMs - 460 kph ( 1 minutes emergency boost)


If i put my money on 109 E speeds i think most reliable data for serial planes would be:

109 E with Db601 E

- at sea level, 1/4 radiator open, 1.3 Ata 2400 RPMs - 467- 475 kph ( depend of version and windscreen type - standart E-4 new windsreen was more draggy so it should cost a few kphs)

109 E with Db601 Aa

- at sea level , 1/4 radiator open, 1.35 Ata 2400 RPMs - 475-485 kph.

Emergency power 1.4-1.45 Ata should add some few kph at sea level - i think someone could calculate it but it wont be probably higher then another 10-20 kph.

V15 or V15a? In any case, the V15a tests note a "DB 601A", but they give the rating as 1,35ata (which is the Aa rating). Power ratings also match that of the Aa.

These figures appear to come directly from the Bf 109E operating manual and were clearly for 601Aa. See: http://109lair.hobbyvista.com/techre...als/bf109e.pdf

The answer to both questions is that V15a fully confirmed to serial production aircraft, as the test report clearly notes.

Also note the results achieved in the Swiss tests fully agree with the results achieved with V15a FS/H0henlader supercharger gear testing results. This cannot be a coincidence IMHO.

Like I said, if the two aircraft two speeds is virtually identical at altitude with the same rating, it means that power and drag is virtually the same too.

Drag doesn't change with altitdue, so any meaningful drag or aiframe conditions between E-1 V15a and the Swiss E-3 J-347 can be ruled out.

Propellers are the same.

The only thing that can be different between the two is POWER. V15a has obviously a lot more power at low levels. Now this might raise the question wheter V15a has some kind of ultra-brutal low altitude engine with much more power than the serial production aircraft, but this can be ruled out too, since [b]V 15a's engine was bench tested/b], and it has exactly the amount of power at low levels as a DB 601Aa should have.

So the J-347 has LESS horsepower at low levels.

And it matches V15a's high-gear / Hohenlander / FS gear speed curves almost perfectly.

I mean, HELLOOOOOO? It runs in high supercharger gear only.. That's perfectly suitable if one want to compare the factory VDM props performance under identical conditions to two other type of props (which is what the Swiss were doing).

In other words: under similar testing conditions, boosts and correcting (ie. not fully corrected), both the pre production WNr. 1791 and 1792 fully support the WNr. 1774 (V15a) figures.

The December 1939 manual gives 1.3ata max ratings, so it's clearly for the 601A-1 version (early Lader).

Comparison the Manual's climb rates and speeds (at unknown rating) show practically identical match as the RAE trials which OTOH are known to have been performed at 1.23 ata 30-min rating, so in all likelyhood the manual also shows 30-min rating.

462 kph at the 30-min rating at SL is fairly believable for the 109E / 601A1.

Note the French aircraft is again a practically exact match with the V15a figures at low levels (as measured at 1.31ata, the French one was running at 1.3ata).

The French aircraft was not developing full boost over altitude for unknown reason (French oils used in tests are suspect) but only about ca. 1.2 ata. In other words, they achieved about 550 kph with 1.2ata.

US tests did not measure the captured '109E' speed anywhere near ground level..

Lowest measured value was 336 mph at 12k feet (541 kph at 3657 m) using the low altitude supercharger. In comparison V15a achieved 532 kph at (uncorrected) 1.33ata, and 545 kph at (corrected) 1.35ata.

As a matter of fact at known measurement altitudes the US trial matches even exceeds the V15a data..

I Agree.

It was introduced early and in large numbers.

As demonstrated above, this opinion is decidedly incorrect.

The V15a results match other results exactly, IF THE SAME CONDITIONS AND CORRECTIONS ARE APPLIED. Problem is, most of the other tests being waved about are either uncorrected, simplistic or are for different conditions (different engine, different boost).

Also the V15a's loadout is as detailed if not more so than any other 109E tests (definietely more so than the completely unknown conditions of the Swiss test, for example).

One can't compare apples and oranges.

This is incorrect because both V15a trials and the Baubeschreibung Leistungsblatter also detail DB 601Aa performance.

The most likely reason 1c decided to model the DB 601Aa variant is that this is what was best documented (both in manuals and for performance tests).



Well the question is basically this:

Should we correct FM to match the airplane modelled, or match the airplane to the FM modelled?

Should we compare our exiting FM's accuracy with tests using different and lower powered variants of engines we have modelled or not?

Should we use official / guaranteed performance specs for all aircraft (which is the V15a figures) or just pick the worst ones for each plane we can find from the bottom of the tolerance limits?

Should we model aircraft after essentially undocumented speed curves, in which the actual flight conditions are completely unknown or based on tests which are well documented and all airframe conditions, engine outputs are documented, known and also - can be replicated in the sim?

Should we apply the above decision to all aircraft, or just apply it to some aircraft, as it fits our taste?


BTW ain't the Spitfire's FM based on the Spitfire prototype? No problem with this one, eh?

Nope. The speed charts posted by BlackSix are based on the performance test of N3171 (http://www.spitfireperformance.com/n3171.html). Interesting notes on engine power of this aircraft:

Well the figures people have been asking for the Spitfire, 285-290 mph or so at SL, are strikingly similar to those achieved with the Spitfire prototype. Which if I got the spiriti of the thread right, means that our Spitfire should realistically do about 250-260 mph tops. It's a PROTOTYPE and all that you know...

I am also asking that because N3171 trials did not measure speed near SL (or under 8000 feet) at all.

So on what are complaints about the lack of SL speed of the Spitfire as based again? A trial that did not even measure SL speeds or that infamous crayon curve?

I am very cynical here of course, but in that context, it's a somewhat difficult to understand the extremely demanding attitude displayed by some for the 109E performance on the other hand.

I mean if a crayon drawing will do for the +12 Spitfire :D surely four seperate timed runs on a record course with calibrated and recorded instruments, a bench tested engine, with the results being corrected for Normaltag and the nominal engine output and guaranteed by manufacturer will do for a 109, would it not.

The problem was there were no 109E1's or 109E-3's in production or service at the time V15 was constructed. V15 was clearly a prototype.

According to Uwe Feist in "The Fighting Me 109", published London: Arms and Armour Press, 1993, there were two prototypes built to test the 109 with the DB601: V14, which had two MG's in the nose, and two F/F 20mm in the wings and which was equipped with a DB-601Ao engine, and V15, which had only had the two nose MG's, (no weapons mounted in the wings at all) and which it appears, was equipped with the DB-601Aa engine.

According to Wiki, V14 was determined to be the more successful of the two prototypes, and there was an initial pre-production order of 20, designated E-0. Later, early production 109E's were sent to Spain to be tested with the Condor Legion. Production later commenced with the E-1 variant, with two MG's in the wings.

This information clearly points out the difference between V15 and the later production aircraft. This aircraft did not have the drag or weight of a pair of MG F/F's and their ammunition to contend with. And who knows what else was not present?

The question is, where is the test of V14?

I would take Luftwaffe data only as confirmed data, Wiki or old books are not always to be regarded as reliable to be honest.


"It clearly points out"................nothing




.

I don't think it is questionable if aircraft's condition is representative enough for a standard 109E. I'd say it is close enough, there are always differences between individual aircraft, even if all of them are brought up to the same specs. Weight is pretty much irrelevant at high speed, and drag from wing installed weapons was shown to be small. I also think the methods employed are sound, and the data is as solid as test data can be.

So far so good, but for me there are other open questions, mostly regarding high altitude performance. It was brought up in another topic - a plane going 500 at SL should manage a lot more than 575 at 5000m, if it has slightly more power available at altitude. Doesn't make sense the way it is. Also, V15 having a DB601Aa engine, the full throttle altitude of 4900m is unreasonably high, no answer found as of yet.

Spitfire tests do not show this kind of problems, which makes it easier for me to accept their results. They are more plausible. OTOH, Spitfire test results usually get less corrections and would therefore be less accurate.

Yes.

We are not discussing V14 (WNr 1029, first flew April 1937) V15 (WNr. 1773, first flew december 1937) but V15a (WNr. 1774). V15a had four MG 17s, as the report notes:

"An Bf 109 V 15 a, der Mustermachine für die E-1-Serie, wurden die Geschwindigkeitsleistungen erflogen. ... 2 Flügel- und 2 Hauben-MG eingebaut."

Again we are talking about V15a, not V15.

Good question.

Actually, this is not an 'old book', it is not one of Heinz Nowarra's 1960's era collection of misinformation, it is one of the newer generation of published works on the 109. Second, I would take the information of a published author as reliable and only discredit it when primary sources disagree. In this case, the primary sources are incomplete. There are two original pages of the V15 test available, (Blatt 4 and 6)and one page mostly transcribed by Kurfurst, (Blatt 5) with only small sections from the original page shown. None of them includes the weight of the aircraft or the details of the armament or equipment.

Another note re. V15:

As mentioned, neither the 109E1 or 109E3 were in production when V15 was constructed, so it was impossible for it to be modelled on them, they didn't exist. As anyone who has looked at the history of the 109 knows, the 'V' designation indicates a prototype or test aircraft.

Where is the page from this report which you are quoting? Please post it here if you have access.

Second, if your quote is accurate, then it is clearly not an E-3 which is being tested, it is an E-1, which was lighter, not having the MG F/F 20mm cannon and ammunition, and faster.

The sea level speeds of the E-1 and E-3 were noted as clearly being different.

E-1: (this is a test a full year later than the V15 test, AND it is of a PRODUCTION 109E-1)

http://www.wwiiaircraftperformance.o...109E1-1791.jpg

E-3

http://www.wwiiaircraftperformance.o...109e3-1792.jpg

If you are arguing the 109E-1 should be faster, perhaps to the V15a, (please provide the missing page) then perhaps you have a case, although the above document suggests speed should be higher than the E-3, but considerably less than V15. As far as the E-3 and E-4, many questions remain, nothing has been proved to suggest their speeds should be similar to V15's.

I agree.

Why? How about +12 Spitfires...? They seem to be claimed to go Thing is, the 601Aa doesn't have more power at altitude, it's pretty much the same at all altitudes.

Here's another take on it. If you look at Spitfire I speeds, roughly 285 mph at SL and about 355 mph at FTH, and the Merlin III's output, you will see that the Merlin has a good deal less power at SL than the DB 601A/Aa (about 870 HP vs 1045 PS).

At rated altitude, the Merlin offers a bit more power, but the two aircraft reach about the same top speed. In short, the 109E needs less power at altitude, which quite clearly points to less overall drag in the high speed regime.

So how on Earth would be it be slower or just as fast than Spitfire with more power (100-150 PS more) near SL...?

[/QUOTE] Also, V15 having a DB601Aa engine, the full throttle altitude of 4900m is unreasonably high, no answer found as of yet.[/QUOTE]

I don't think it's very unreasonable, 1000-1200 m gain in FTH due to high speed rammed power seems fairly typical, and it's seems it is what in all tests agree.

Because we have so few Spitfire I tests. ;)

I must have missed the speed charts for Prototype K.5054, the earliest I know is the test of the the production aircraft K.9787 (http://www.spitfireperformance.com/k9787.html) which has 291 mph at sea level.

Yes, but.... according to the RAF documents, except for takeoff, 3000 RPM and +12 boost should only be used over rated altitude, below rated altitude, 2850 rpm was recommended. However, this did not stop pilots from using 3000 rpm and +12 boost down lower.

The fact is, pilots will do things which are not necessarily in the manual, just because they are pilots. ;)

If you want to open up a discussion of the Spitfire's performance, feel free, but in this post, the subject is 109's. At this point you are only serving to muddy the waters with unrelated material.

I'd like to see the document where V15's loadout is mentioned.

This is only a false interpretation propagated by Crumpp. The 2,850 rpm/3,000 rpm restriction is the 30 minute climb rating (+6.25 boost). In normal conditions this is restricted to 2,600 rpm, in combat/emergency condition however 2,850 rpm is permitted below FTH and 3,000 rpm above FTH.

Just think about it: It is not possible to achieve +12 boost above FTH, why put a restrict on a boost for an altitude where this boost is not possible?

But enough of Spitfire talk, this topic is about Bf 109.

Just reading and summarising the information in this thread, ideally there would be both engines modelled:

DB 601Aa for E-3/B, E-4/B (and E-7 eventually)
DB 601A-1 for most of the other Emil variants, especially without bomb racks installed (E-1s, E-3s and E-4s in the sim)

It is known that due to overhauls and re-builds, there were all combinations possible and I am not taking the superchargers in account.

Only cca 3 out of 10 DB 601s made were Aa.

DB 601Aa = full throttle height of 4000m, rated at 1,35 ata (1,45 max)
DB 601A-1 = full throttle height of 4500m, rated at 1,3 ata (1,40 max)

Looking at the above, the only DB601 modelled in the sim has got the rated power of Aa and fth of A-1.

Any documents at the different FTH of the two above supercharger types? Different supercharger (improved or new design) usually shifts the power curve of an engine, e.g. gaining in low level performance for the cost of lower fth. Alter und Neuer Lader do reflect this change in the Baubeschreibung page posted by Buszsaw.

We do have these rated power but we also have the FTH of 4,5 km. See above. It is my understanding that the neuer und alter Lader reflects the A-1 or Aa subtype in the relevant documents because these were only referred to only generally as DB 601A without specifying the subvariant. Aa was indeed intended for export, but ended up being used by the Luftwaffe in considerable quantities (cca 25%) and on pretty much random basis.

Salute

There is also this document, dated 24/7/1942 according to Mike Williams site where it is located.

http://www.wwiiaircraftperformance.o...zeug-daten.jpg

It indicates a much more conservative speed than some of the previous documents.

I am also very interested in any German speakers interpretations of the following three documents, dated August of 1940, also found on the WWII Aircraft Performance site:

http://www.wwiiaircraftperformance.o...endezeiten.jpg

http://www.wwiiaircraftperformance.o...rvenradien.jpg

http://www.wwiiaircraftperformance.o...rvenzeiten.jpg

The below document, dated October 1940 by the WWII Aircraft Performance site is from the manual I have already posted,

(http://www.scribd.com/doc/32387854/Handbuch-DB-601-A-B)

...and indicates the DB601A and B had both variants of superchargers installed, both the 'Neuer' and 'Alter' lader, but the limit for both was 1.40 for takeoff and 1.30 for 5 minutes.

http://www.wwiiaircraftperformance.o...manual-p21.jpg

By the way, can anyone shed any light on the methodology to convert the German method of measuring boost, ie. 'ATA' to 'Ft/pounds', or 'Inches of Mercury'.

Salute

And one more.

The following document is only really relevant to the 109E-1, although it does show the E-3 weights, which by the way indicate that game aircraft is underweight.

The primary use of it is that it shows production E-1 speeds at 1.15 ata boost, ie. continuous cruising speeds. Measurements could be taken at this boost level to determine if the aircraft meets these specifications.

http://www.wwiiaircraftperformance.o...datenblatt.jpg

Yes I am familiar with that document but as usually, it does not specify the subversion of DB 601A (e.g. A-1 or Aa) and is rather generic (includes all A dn Bs, difference being the gear ratio). It actually mentions the details about the new supercharger, like 1mm Drahtstaerke) and different FTH at Hoehenlader as result. My understanding until now was that the new s/c column is for the A-1 and old s/c is for the Aa, hence the FTH difference. I see there is more to it so I am interested in details - how many engines have had the old s/c fitted and what was the technical difference and so on.

I simply don't know so I did not consider the various supercharger combinations at all in my original post.

It is obvious though that in case we have the Aa modelled, the FTH is wrong.

1 ata = 1kg/cm^2 = 14.2 lbs/in^2 = 28.96 inHg

I guess you misunderstood something.

Motorunterzetzung DB 601 A = 1:1.55
Reduction gear ratio DB 601 A = 1:1.55

1 ata = 1 kg / square centimeter. I am not going to convert this to PSI (0.454 kg = 1 lbs, 2.54 cm = 1 inch, have fun :D ) but keep in mind the British used relative boosts, ie. (+) 0 PSI = 1 ata, and + 6.25 PSI boost on the Merlin III is 1 ata plus whatever 6.25 PSI is in ata.

Bottomline, the Merlins always used much higher boost than DBs to compensate for smaller displacement. IIRC the 1.7 ata boost of the methanol boosted 605AM was something like +7 PSI..

Probably that would be the best historical approach, though since there was a lot of E-7/N (in fact most the post-bob production which will make appearance in BoM) I would say that 601N would be a more practical choice.

Problem is, we are end of the development line, and 1c certainly not going to give us 3 seperate variants. The only diffo between the A and Aa is probably that the latter is maybe about 10-15 km/h faster down low.

Depends. Engines have higher FTH in high speed flight. An Aa should get about 3700m in climb and 4800 m in full speed flight (the latter being a bit problematic with the current poor altitude model)

Yes I do have these old/new 601A curves but I believe both are uploaded to aircraftperfomance.org recently.


Yes more or less that's my understanding too. Of course the Aa has curves too, but these are Mercedes's own manual.

I believe he refers to the second (bottom) part of that document titled Reichweiten where we see the speeds at 1,15 ata Dauerleistung at 1, 3, 5 and 6km altitude (only 0,92 ata achievable at 6km) so I guess he was right in his assumption.

Salute

You are suggesting this is a test of a different reduction gear?

Because in fact the speeds shown are achieved at a boost of 1.15 ata.

Thank you very much for the info about the superchargers, superb! ;)

I am aware of RAM effect, but the current FTH in the sim (for all Emils) is 4,5km in the climb. (I would need to re-check that in the current beta patch.)

You could also change the "German" to "English" here...

Oh, my bad, didn't scroll down LOL. :D :D

You are welcome. :)


Oh, something is fuzzy then... indeed it looks like the neue Lader, I wonder if someone has the most recent engine file data, I remember seeing them on the forum some time ago.

You do have examples you can post, yes?

On the Bf 109 E-3/b, E-4/b and E-7 and the engine thingy. Do not distinguish the bomb carriers too much, especially not when talking about the engine. IIRC not a single E-3/b was produced (unsurprising since the E-3 went out of production even before the Luftwaffe even thought about using the 109 as Jabo) so any potential aircraft of that type would be converts. Although this is somewhat doubtful since they would most likely be upgraded to E-4 standards at the same time and labeled E-4/b afterwards, anyway.

IMO the E-4 (and E-4/b) would be the most probable candidates for the 601Aa while E-1 and E-3 should feature the 601A. IMO, of course. ;)

According to rather old FM files there is a DB601A and DB601Aa. The Bf 109 uses the DB601A, only the He-111 P uses the DB601Aa.

Both engines have the same FTH (4500m), max boost (1.35) and WEB (1.45) values. The difference that I found:
- DB601Aa has a higher ramming factor
- DB601Aa has a constant speed propeller

Buzzsaw,

To answer your questions about the V15a, yes its an E-1, but no, I do not think there was any meaningful difference between the E-1 and E-3 aerodynamically. Only the fitted armament was different. Now one of the test you have posted show that there was 0 to 1 kph "difference" between the MG FF being present or not.Other than that there was a slight bulge under the cannon drum in the underside of the wing. I do not know what drag that was responsible for, but I do have British tests for the Spitfire which give a speed difference of a whopping 1 mph for the similar bulge for the Hispano ammo drums...

As for the V15a test, the full paper has been transcribed on my site
http://kurfurst.org/Performance_test...w_109V15a.html

and I have also recently uploaded the originals to this forum, you can find in one of my recent postings in another thread.

As for the 3 papers you have posted, they are turn times and radii for the 109E at 0 and 6000m, at various flap settings.

So it is safe to state that the DB601 family is not modelled correctly regarding FTHs and max MAPs and the engine of any Emil in the sim is a mix of both Aa and A-1.

There was a theory that the Aa low alt performance (take-off HP) was desirable for the JaBo variants and therefore Aa DBs were primarily used for /B variants. Only 25% 601s were Aas. This theory is supported by the fact that every JaBo 109 examined after being shot down has had Aa engine (AND the bomb rack installed.) I am aware that this is just a theory and it is not mine after all, but it makes sense.

Maybe you are right and the numerous engine overhauls would cause for majority of the later BoB Emils flying with Aas despite the lower overall number of 601 made (e.g. one airframe could have several engines installed during its lifespan). What we have now is a DB 601 with A-1 FTH and Aa rating, that is certainly incorrect.

IMHO the realistic max speed for the Bf 109E series, based on the V15a trials and the official specs and the French trials etc., are:



At SL.

DB 601Aa, 1,35 ata (1045 PS) : 498 km/h (V15a @ 1.35 = 498 km/h, Baubschrb.5% @ 1.35 = 500 km/h)
DB 601A, 1,30 ata (990 PS) : 489 km/h (V15a @ 1.31 ata = 493 km/h, French109 1.3ata = 485 km/h)*

DB 601Aa, 1,45 ata (1175 PS) : 515 km/h*
DB 601A, 1,40 ata (1100 PS) : 506 km/h*

Similiar boost in speed up ca. 1500 m, above: essentially 1.3/1.35ata performance levels, but boost is maintained, and fuel consumption increased to ca. 375 lit/h.

* Calculated from 1.3ata / 1,35ata results for 990 PS / 1075 PS

At altitude.

DB 601Aa, 1,35 ata : 570 km/h @ 4800 m (V15a @ 1.35 = 572 km/h, Baubschrb.5% @ 1.35 = 570 km/h, Swiss 109E-3a = 564 km/h)

DB 601A, 1,30 ata : 562 km/h @ 5200 m (V15a @ 1.33 ata = 562 km/h, French109 1.3ata = 485 km/h; 1942 Emil chart with 601A = 562 @ 5200)


P.S. Note that atmospheric conditions in the V15a and French trials are very close (+5, +6 Celsius) which explains as well why the results match so well.

Note that the 1942 Emil chart is again based on the V15a results. Given the weight it probably includes the armored bulkhead.

If CloD's 'standard day' is different from German (British) Standard day for which these figures were corrected to, then they should be re-calculated to CLOD standard day first.

493 of V15 @1.31 were done at 500m altitude, at SL this was extrapolated to 485.

485 was not yet corrected to Normaltag (standard day) conditions as I understand.

It's curious though, I think it needs to be looked into. If you are right, it's an even closer match to French figures..

Just a a side note, me being someone that is in no way an expert on all this stuff, but it almost seems that what is being talked about here is almost out of the realm of what the CloD FM can calculate properly. As an example, how does it calculate weight correctly if its only based on either full or empty, no inbetween.

Now maybe I just dont understand their FM data and perhaps there are calculations going on that I dont see, but as you expend fuel, ammo, etc, the weight and flight characteristics will change.

So are we asking too much of the CloD FM? Would be interesting to hear what the programmer had to say about it, what knowledge he had on flight models, engineering background, etc... or if he is just a programmer punching in numbers without too much thought into what they actually are... if that makes any sense.

Not trying to rain on anyones parade or anything, just mostly a comment on the level the current FM could actually handle. And if throwing all this data around really matters if the FM itself can even really handle it.

Yes, you are right, it's not corrected. If you apply the method they used for the Aa engine and use A-1 performance with 55 PS less at low altitude, you end up with 490 km/h (r = 0.993752), corrected both to standard days conditions at SL and nominal engine output.

DB 601A, French109 1.3ata = 570 km/h @ 5000 m - 5500 m - Closed Radiators
http://kurfurst.org/Performance_test...formanceT.html



Regards

The weight throughout flight DOES make a difference in game. Easist test you can do is take a 109 with 10% fuel and a 250Kg bomb... Take off and drop the bomb, then repeat with 100% fuel... You will definatley see a dramatic difference. ;)

Large change in Drag to in this method.

Salute

Sorry Kurfurst, your answer is clearly not accurate.

Firstly, You have not provided an original document which shows the loadout, weight, or boost levels of the the V15 aircraft. If you have the full test, show the originals, not transcribed incomplete sections.

Secondly, the V15 is clearly not a production aircraft, there were no production E-1's till late in 1938 and early in 1939. The date of the V15 test is April of 1938, long before any E models were produced. V15 is one of several prototypes produced to test the installation of the DB601 engine in a 109 airframe.

Here is a excerpt from 'Messerschmidt Bf 109' by Robert Grinsell. This is one of several sources I have consulted which clearly trace the evolution of the 109E model, and which are in general agreement. The section of relevance, begins with the 109E header.

http://imageshack.us/a/img18/4252/reference1m.jpg

As the above notes say, V15 was one of three early pre-production aircraft which were built in 1937 and which had the DB-601 installed and tested in various forms. These were V13, V14 and V15. I could not absolutely confirm a picture of V15, but I believe it is one of the lower or upper aircraft on the following page, as no others of this type were constructed. V14, the identical brother aircraft to V15 is definitely identified. You will notice there is no armament installed on V14 or the other two aircraft.

http://imageshack.us/a/img141/9708/v14r.jpg

At this time, Germany was orchestrating a propaganda campaign to convince potential enemies that it had a formidable and powerful air force with aircraft which outperformed all opponents. At this time, Germany was potentially moving into a conflict situation over its claims on the Sudetenland and Czechoslovakia. In fact, the latest model of the 109 in service, the 109D, was slower and climbed worse than the initial model of the Hurricane then in service. The Luftwaffe attempted to mislead British and French observers by sending highly modified versions of the 109 to air competitions. Below is a picture of V13 in its initial form during the July 1937 Zurich International competition. In the case of the July event, V13 was equipped with a modified 1560 hp DB-601 engine, (misidentified in the caption as a DB600) which allowed it to win several events. These engines were designed to only last a few hours, used special fuels and boost levels. The Luftwaffe claimed their entries were 'production', in service aircraft, despite the fact no 109's were in service with Daimler Benz engines at that time. No armament was visible.

http://imageshack.us/a/img211/5816/v13a.jpg

V14, also equipped with a 1560 hp DB 601, was also present, and flown by Ernst Udet, head of the Technical Office of the Luftwaffe, but it crashed. Below are pictures, again, no armament is visible.

http://imageshack.us/a/img834/4718/v14crash.jpg

In November of the same year, at a second international air competition, V13 made another appearance, in even more highly modified form. This time it was powered by a more heavily boosted DB601 which produced 1650 hp. This aircraft also had a large number of other modifications, including a special spinner, highly polished frame, and special radiators. And quite obviously, it has no armament. It achieved a top speed of 379 mph/607 kph at sea level. It was claimed to be a production, service aircraft. Seen below:

http://imageshack.us/a/img809/1862/v13b.jpg

The aircraft was flown by Dr Wurster, the chief test pilot for Messerschmidt. You will notice that the V15 test also has Dr Wurster as test pilot. During 1937 and 1938 V15 was being used a testbed for various engine, boost, radiator, and oil cooler configurations. It continued in this role through 1938 and into early 1939, then was retired.

According to the several sources I consulted, it is clear this aircraft did not have standard armament, if any, and that it was equipped at various times with highly modified engines.

The fact the results of the posted V15 test are not duplicated by any other of the tested actual E series aircraft is a clear indicator its results were obtained with non-standard equipment.

Sources

'Messerschmidt Bf 109' by Robert Grinsell
'Bf 109, Versions B-E' by Roy Cross, Gerald Scarborough and Hans J Ebert
'Messerschmidt Bf 109' by Heinz J Nowarra
'Spitfire vs Bf 109' by Tony Holmes
'Messerschmidt Bf 109, Owners Workshop Manual', by Paul Blackah and Malcolm V Lowe

We are discussing V15a, not any of the previous prototypes like V15, V14 or V13.

Bf 109E-1 V-15a WNr. 1774 was the last in prototype I know of, it was fully armed with 4 x MG 17s and in representative condition of serial production aircraft, the complete testing paper was provided on this forum if anyone wants to doubt my transcription.

I am not discussing red herrings about previous or different aircraft, therefore on my part I have put an end to this part of discussion.

In fact, as mentioned above, there were a number of prototypes after V15 designated for testing of the 109E series, they included V16, V17, V18, V19, V20, V21, V22.

As far as continuing the discussion, I will say I am still of an open mind if someone has further information on this aircraft and the test. At this point though, it would seem clear that a) it was a prototype, b) it was not armed with standard E series weaponry, c) Boost levels, fuel type and weight are unknown.

Geschwindigkeit Bf 109 V15 a
--------------------------------


Ü b e r s i c h t.

An Bf 109 V 15 a, der Mustermachine für die E-1-Serie, wurden die Geschwindigkeitsleistungen erflogen. Aus Zeitmengel konnten nicht die günstigen Rückstoßer und Ansaughutzen erflogen werden, sodaß evtl. noch Leistungssteigerungen möglich sind.

A n g a b e n

Maschine Bf 109 V 15 a D-ITPD W.-Nr. 1774

Motor DB 601 A W.-Nr. 140

Schraube 3 fl. VDM Verstellschraube 9-11081 W.-Nr.17459

Wasserkühler 1/4 geöffnet (Klappe in Straak) Wassertemperatur konstant = 90° bei +5° Außenlufttemperatur

Ölkühler Klappe geschlossen Öltemperatur 62/82°; Öldruck 3,2 kg/cm2 bei +5° Außenlufttemperatur

Ansaughutze Ausführung 1 Zeich.Nr. S-10361

Profil der Umlenksschaufeln ist so gewählt, daß Kanalquerschnitt fast konstant, bis auf eine kleine Verdickung der Vorderkante zur Erzielung einer runden Profilnase.

Rückstoßauspuff DB-Rückstoßer, von BFW angefertigt

Zustand des Flugwerkes

Oberfläche : serienmäßiger Anstrich, Motorhaube noch roh, Rückstoßer oben unverkleidet. 2 Flügel- und 2 Hauben-MG eingebaut. Eindrahtantenne. Fahrwehr eingezogen, Sporn außen.

Aparently there's something on it in "Radinger, Schick, Otto: Messerschmitt Bf109" Aviatik Verlag, Oberhaching 2011, ISBN 978-3-925505-93-5. Don't have that book, but who knows ...

No, the CoD results should be converted to Standard Day (which my test mission does) to ensure all results are on a level playing field when they are compared (109, Spitfire, Hurricane etc)

I'll try to finish the 109 tests this weekend. It won't be "max speed tests" but a test at 2400 / 1.3 and 2400 / 1.35 to compare with historical charts and avoids arguments about what max speed power settings should be.

BTW how do you measure TAS?

from "Radinger, Schick, Otto: Messerschmitt Bf109" Aviatik Verlag

V-15
BF-109, W.Nr. 1773; D-IPHR
Engine DB-601A, W.Nr. 140 with one-stage compressor [4km full pressure] (einstufiger Lader, 4km Volldruckhöhe), 1100 PS
VDM-Verstellschraube with 3,10m diameter
400l fuel tank
armory: 2MG 17 in fuselage, 2MG 17 in wing

Half hour flight on 4. Feb. 1938 in Augsburg and tested at the same day in Rechlin.
In April back in Augsburg and used as prototype for Bf-109 T-series wing tests.

interesting is that that both prototypes suffered power loss in full pressure height.
V15: 146PS in 3900m height tested on 6. 7. and 9 May 1938
V15a: 200PS 26. April 1938
How this problem was solved is unknown to the authors since there is no report.


EDIT: By the way L.Dv.556/3 says for E-1, E-3

height / Max. Speed
0 km / 460 km/h
1 km / 480 km/h
2 km / 500 km/h
3 km/ 520 km/h
4 km / 540 km/h
5 km / 555 km/h
6 km / 555 km/h
7 km / 550 km/h

Max. allowed horizontal speed at SL 485 km/h

Engine: DB-601A (full pressure height 4 km)
at SL:
1min. power 1175 PS at 2500 rev/min
5min. power 1015 PS at 2400 rev/min
30min power 950 PS at 2300 rev/min
continuous power 860 PS at 2200 rev/min

power in height:
5min. power in 3,7km 1100 PS at 2400 rpm
continuous power in 4,1km 1050 PS at 2400 rpm
continuous power in 4,5km 1000 PS at 2400 rpm
economic continuous power at 3,85km 975 at 2250 rpm

VDM-Verstellschraube 3,10m diameter

Salute

Thanks for the information, your books quotes for horizontal speed of E1 and E3 types agree with this test approx. time period of E-1/E-3 production, as per this table:

http://www.wwiiaircraftperformance.o...dbookcurve.jpg

I am not convinced there were two aircraft, each would typically be numbered differently if the system used in the numbering of all the other prototypes was followed. It seems more likely, the designation 'a' might mean the same plane with a different engine installation or some other equipment.

The fact V15 was being used as a test bed for a potential 109T model in April at the same time as Kurfurst's test, is a likely indicator of why its performance envelope in that test was completely different than a standard E model and why speeds were so high at sea level. Carrier borne fighter aircraft require more performance at lower altitudes, the final 109T was built with the DB601N engine using higher octane fuel, not with the DB601A using the standard 87 octane variety. With the note that the engine was allowed to rev to 2500 rpm, not standard in the DB601 in this time period, see table below, it may be there was an attempt to gain power at takeoff and at lower altitudes. Whether or not V15 was being tested with higher octane fuel is a question which needs to be answered.

http://www.wwiiaircraftperformance.o...ginelimits.jpg

In any case, the fact seems to be that V15's test was not representative of a standard E-1.

Yea i also think that 109 E protoype test are not adequate for serial production of 109 E.

Looking at German charts with serial 109 E speed test i think that sea level speed at 1.3-1.35 Ata ( 5 minutes emergency power) should be between: 467-485 kph depend of condition of plane, engine type and type of windscreen and equimpent.

How is it possible that IAS and TAS are different at 0m altitude? Position error? Why is IAS equal to TAS at 0m altitude for best climb speed?

Since those instruments have springs in it, you can only adjust them perfectly for one messure point (in this case 250 km/h at ground? ). The rest is within a given tolerance.

It is also with old speed-indicators. Their are mostly adjusted to 50 km/h by motorcycles (with top speed below 150 km/h), the rest is tolerated inaccuracy.

There are two ways I use.

One is to take the CoD C# Parameter Z_VelocityTAS for TAS which I have been doing because I was finding the calculated value to be fair bit off the game parameter (which I have now fixed and is very close to game paramater now, see second method below).

The second method is to calculate from the IAS (I_VelocityIAS), converting through Pressure Altitude, i.e. adjusted from actual baro pressure to Standard Day Pressure and then to Density Altitude which adjusts it again taking into account actual Temperature vs Standard Day Temp.

Formulas are here:
http://williams.best.vwh.net/avform.htm#Altimetry

See "Relationship of pressure and indicated altitude:" for Pressure Altitude
and
"Relationship of pressure and density altitude:" for Density Altitude.

My full method is here:
http://forum.1cpublishing.eu/showpos...6&postcount=10

.....although I have tweaked the .cs file since then simply to correct the calculated TAS. I'll try to replace the zip file over the weekend. I'm currently working on a Bf109 set.

Beware of the indicated airspeed C#parameter Z_VelocityIAS as it seems to be wrong and far too close to Z_VelocityTAS even at altitude.

"Surface: identical to serial production,
The engine cowling still rough, exhaust manifolds lacking top cover."
It seems that in serial production the aerodynamics will be a little better.