Bf109 test data

[*Buzzsaw*]

Originally Posted by Kurfürst

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.

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?

[KG26_Alpha]

Originally Posted by *Buzzsaw*

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




.

[JtD]

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.

[Kurfürst]

Originally Posted by *Buzzsaw*

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.

Yes.

Originally Posted by *Buzzsaw*

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.

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."

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?

Again we are talking about V15a, not V15.

The question is, where is the test of V14?

Good question.

[*Buzzsaw*]

Originally Posted by KG26_Alpha

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




.

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.

[*Buzzsaw*]

Originally Posted by Kurfürst

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."

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)



E-3



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.

[Kurfürst]

Originally Posted by JtD

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.

I agree.

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.

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.

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.

Because we have so few Spitfire I tests.

[41Sqn_Banks]

Originally Posted by Kurfürst

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 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.

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.

[*Buzzsaw*]

Originally Posted by 41Sqn_Banks

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.

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.

[*Buzzsaw*]

Originally Posted by Kurfürst

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.

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.