109 performance notes

[gripen]

Originally posted by BlauK

Seems to me, that sometimes when you cannot base your arguments on data, you revert to playing silly tricks with semantics. Please look back at the theme of this thread and present your arguments with data.

Hm... I have claimed that the GL/C-E data for the G-14 seems to be a calculation and I have posted data which indeed states that the values are calculated ie "rechnung".

Originally posted by BlauK

If your only argument is that calculations do not always provide reliable data, why are you bringing it into discussion about how the "new" 109:s perform in the game?

Actually the others came up first with the argument on the historical performance of the G-14. I merely posted a note that the so called historical performance seem to be a calculation without any opinion if the calculation is right or wrong. The others started to argue about the validity of the calculations.

Originally posted by BlauK

Furthermore, your evidence cannot claim that calculations never provide reliable data... so what is the point?

I wonder what you might mean, I have not claimed that the calculations never provide reliable data. The others came up with the arguments like "Calculations tend to be conservative not optimistic", my opinion is quite different.

Originally posted by BlauK

Actually I have yet to see you criticize any allied data on these boards... then again, I have not been reading such threads with great interest.

Well, you should dug some of the old P-38 threads.

Originally posted by justin_g  

What DOES matter is the condition of the aircraft in question - as has been pointed out - the 732kph G-1 was not based on a standard condition serial aircraft.

What does matter is that the DB 605 did not live up to estimated performance  and the efficiency of the propeller at high speed is too low for such performance. See Raunio's article, it contains quite a lot analyses on the Bf 109G.

gripen

[Kurfürst]

Did the Russians actually do the full speed tests?

gripen

Yes gripen, it was a captured 109G2, I have the Wrknr too somewhere. Butch2k has the full Soviet report on that tests, it's some 17 pages afaik, they did tests with and w/o gunpods. There are even pictures of that plane, posing with the Red Star on it's wings.

In clean config the captured G-2 did 530 kph at SL, 666kph at 7000m, at 1.3ata kampfleistung, within (actually higher) 5kph of Messerschmitt's calculations.

In other words, Mtt's calculations are VERY accurate for the aircraft of the same conditions.

What does matter is that the DB 605 did not live up to estimated performance and the efficiency of the propeller at high speed is too low for such performance. See Raunio's article, it contains quite a lot analyses on the Bf 109G.

Oh well, I guess that's just other claims you need to back up with something...

You need to back up :

"the DB 605 did not live up to estimated performance"
"the efficiency of the propeller at high speed is too low for such performance"


We have already seen how accurate Mtt's calculations were, ie. they calculated 660 kph at 7000m, Soviets actually achieved 666kph with the same type of plane. Pretty convincing, huh?

[gripen]

Originally posted by Kurfürst

Yes gripen, it was a captured 109G2, I have the Wrknr too somewhere. Butch2k has the full Soviet report on that tests, it's some 17 pages afaik, they did tests with and w/o gunpods. There are even pictures of that plane, posing with the Red Star on it's wings.

So far no one has come up with proofable data from these tests. Infact even those who have supposedly seen the data, have had problems to read the text. It's not known if the data is calculation or real test data.

Originally posted by Kurfürst

We have already seen how accurate Mtt's calculations were, ie. they calculated 660 kph at 7000m, Soviets actually achieved 666kph with the same type of plane. Pretty convincing, huh?

As you have allready seen, the Mtt tested Bf 109G did 626 km/h at FTH 6100m with the 1,3ata and 2600rpm. In the Erla set (13 planes), none of the planes reached 7000m FTH the average being 6700m and highest being 6900m (probably above spec rpm and/or below spec MAP).

gripen

[justin_g]

Originally posted by gripen
What does matter is that the DB 605 did not live up to estimated performance  and the efficiency of the propeller at high speed is too low for such performance. See Raunio's article, it contains quite a lot analyses on the Bf 109G.

Exactly my point - the engine power used in the calculations was not the same as that achieved by production aircraft. It's a case of "garbage in, garbage out".

[gripen]

Originally posted by justin_g
Exactly my point - the engine power used in the calculations was not the same as that achieved by production aircraft. It's a case of "garbage in, garbage out".

OK, if you want to put it that way. To give some idea about the issue, at 10 km the calculated speed for the G-1 (Ausführung) is 632 km/h, which is about the same performance as the prototype 109G-5/AS reached in flight tests with the DB 605 AS and high altitude propeller at same power setting (1,3 ata 2600 rpm).

gripen

[Crumpp]

OK, if you want to put it that way. To give some idea about the issue, at 10 km the calculated speed for the G-1 (Ausführung) is 632 km/h, which is about the same performance as the prototype 109G-5/AS reached in flight tests with the DB 605 AS and high altitude propeller at same power setting (1,3 ata 2600 rpm).

What does performance of the production G-1 have to do with performance of the prototype G-5?  What a totally silly comparison.  

Computations are both aircraft and condition specific.

Flight tested data exhibits a wide range of performance within a given design.

Prototypes can exhibit an even wider range of performance!

With "New Type" aircraft, however, the error might be up to 6-7% in speed, and 200-250 ft./min. in climb.

Only when trials with representative production machines have been carried out under known conditions can the Final figures be issued. These figures then represent the performance expected of an average production machine of this type.

http://www.spitfireperformance.com/

All the best,

Crumpp

[Kurfürst]

Originally posted by gripen
So far no one has come up with proofable data from these tests. Infact even those who have supposedly seen the data, have had problems to read the text. It's not known if the data is calculation or real test data.

[/B]

Hate to point it out, but butch2k is without exception is a very credible and honest person, who has literally tons of documentation on the Bf 109 and always backs up his words with that. I've no reason to believe he has the flight test report on that G-2 that easily made 666kph, especially as Soviet literature also mentions this plane test. The plane is question is identified and the Werknummer is known.

You on the other hand was just caught misrepresenting that '732 kph' datenblatt until you got exposed with it, and not very good at supporting your claims with documentations. You can't even give reference numbers, what's the panic, that someone will take the time, find the report and show it in it's completeness, unlike you who picks out parts of it to support his jihad?

You are the one who don't have the report, but deny that it exists.

 

As you have allready seen, the Mtt tested Bf 109G did 626 km/h at FTH 6100m with the 1,3ata and 2600rpm.[/B]

Uhum, a particular G-1 airframe where tests themselves note the engine problems of the DB 605 engine, probably faulty supercharger. Curious why you don't note that small isn't it, the

 In the Erla set (13 planes), none of the planes reached 7000m FTH the average being 6700m and highest being 6900m (probably above spec rpm and/or below spec MAP).

gripen [/B]

You are welcome to share the details of those tests, so we can all see the conditions of those planes. A reference to your source would be the minimum. I must note that you have already exposed yourself with that little affair saying 'Mtt claiming 732kph in it's calculations,' when in fact it claimed 660kph (perfectly believable), and the one you cherry-picked was the factory's estimation of a non-standard, aerodynamically improved project. Basically there's no reason to believe you.

OK, if you want to put it that way. To give some idea about the issue, at 10 km the calculated speed for the G-1 (Ausführung) is 632 km/h, which is about the same performance as the prototype 109G-5/AS reached in flight tests with the DB 605 AS and high altitude propeller at same power setting (1,3 ata 2600 rpm).[/B]

Oh, geez, not that cheap demagog bs again...

The G-1 was a considerably lighter aircraft (this means a lot at high altitude) with much cleaner lines.

109G-1 weighted some 3047kg a TO, the G-5 weighted 3220kg or so.

Aerodynamically, the G-5 differed from the G-1 having the following extra drag items (speed penelty at SL):

non retractable tailwheel : -12 kph
13mm bulges : - 9kph
wing bulges, maybe 1-2 kph.

Alltogether 22-24 kph at sl, at 10 000m this is about 70% greater loss in speed! Or about 40 kph worth at 10km alt. Now is it a wonder the dirtier G-5/AS airframe even with it's better altitude engine needed a lot more power to get the same speed?

[elkaskone]

I think the "Performance Statistic recorded by the General Luftzeugmeisters/C-E2 13 August and 1 November 1944" is flight data over several Airplanes (Statistic)!
And the 109G6/R2 Reconnaissance with DB605AM has nearly the same Performance like the 109G14 with DB605AM!
- Performance Statistic by GLZM August and November
Me109G6 with DB605A 1310PS - 0m, combat speed, 3196kg
0m 510km/h
6600m 630km/h
Me109G6 with DB605A 1475PS - 0m, emergency speed, 3196kg
0m 530km/h
6600m 640km/h

- Performance Statistic by GLZM August and November
Me109G6/R2 Reconnaissance with DB605AM 1240PS - 0m, combat speed, 3320kg
0m 498km/h
6600m 628km/h
Me109G6/R2 with DB605AM 1800PS - 0m, emergency speed, 3320kg
0m 569km/h
5000m 666km/h

- Performance Statistic by GLZM August and November
Me109G6AS with DB605AS 1275PS - 0m, combat speed, 3221kg
0m 500km/h
8800m 648km/h
Me109G6AS with DB605AS 1435PS - 0m, emergency speed, 3221kg
0m 520km/h
9000m 660km/h

[elkaskone]

[gripen]

Originally posted by Crumpp
What does performance of the production G-1 have to do with performance of the prototype G-5?

I compared calculated performance of the G-1 to the flight tested performance of the G-5/AS. If we compare flight tested performance of the G-1 to the flight tested performance of the G-5/AS, the later is over 50 km/h faster at 10000m at same power setting.

Originally posted by Kurfürst

Hate to point it out, but butch2k is without exception is a very credible and honest person, who has literally tons of documentation on the Bf 109 and always backs up his words with that.

Butch has noted that he had problems to undestand the cryptic content of the report.

Originally posted by Kurfürst

Uhum, a particular G-1 airframe where tests themselves note the engine problems of the DB 605 engine, probably faulty supercharger.

I can't find any note about faulty supercharger from the report? Based on "Gebläsedruck" curves supercharger actually seem to be give better than normal performance at low altitude. Speed at 10000m is very normal for a tested G-1 or G-2.

Originally posted by Kurfürst

You are welcome to share the details of those tests, so we can all see the conditions of those planes. A reference to your source would be the minimum.

It's from the NASM microfilms (I don't know which because I got these from other people), butch2k has a copy if you are interested. There is no details on tested planes but given the dates, these were probably G-1s.

Originally posted by Kurfürst

109G-1 weighted some 3047kg a TO, the G-5 weighted 3220kg or so.

The tested plane weighed 3190kg in take off and it was a AS airframe ie no mg bulges. It was some 50 km/h faster at 10000m than flight tested G-1s.

gripen

[Crumpp]

I compared calculated performance of the G-1 to the flight tested performance of the G-5/AS. If we compare flight tested performance of the G-1 to the flight tested performance of the G-5/AS, the later is over 50 km/h faster at 10000m at same power setting.

It is an ignorant comparison for the reasons stated in my previous post.  

It is impossible to determine the performance of one type of aircraft based off the prototype of another.

Look up the phrase, "rhetorical question" too BTW.  It will keep you from looking like a complete idiot by answering the question.

http://www.wordreference.com/definition/rhetorical%20question

All the best,

Crumpp

[gripen]

Originally posted by Crumpp
It is an ignorant comparison for the reasons stated in my previous post.  

I can't follow your logic here, the flight tested difference between the series production G-1 and the G-5/AS prototype was over 50 km/h. The G-1 simply lacks the key features of the high altitude performance ie high altutitude propeller and the larger supercharger. Besides, the flight tested FTH of the G-5/AS was 8300m while the claimed FTH was 8800m, so the gap would have been even larger if it had done up to the claimed performance.

gripen

[Crumpp]

I can't follow your logic here, the flight tested difference between the series production G-1 and the G-5/AS prototype was over 50 km/h. The G-1 simply lacks the key features of the high altitude performance ie high altutitude propeller and the larger supercharger. Besides, the flight tested FTH of the G-5/AS was 8300m while the claimed FTH was 8800m, so the gap would have been even larger if it had done up to the claimed performance.

This is why people put you on their ignore list, Gripen.

Seems to me, that sometimes when you cannot base your arguments on data, you revert to playing silly tricks with semantics.

Your comparison of:

 

OK, if you want to put it that way. To give some idea about the issue, at 10 km the calculated speed for the G-1 (Ausführung) is 632 km/h, which is about the same performance as the prototype 109G-5/AS reached in flight tests with the DB 605 AS and high altitude propeller at same power setting (1,3 ata 2600 rpm).

Is not a valid comparison for the simple fact the aircraft are different.  One is a prototype with a much larger percentage speed range.

The data was valid or invalid as determined by Mtt for their prototype during the development of the Bf-109G5/AS.  It would have been used or discarded in that program.  That is what prototypes are for in the first place!

To turn around and use that data and compare it to performance estimates of completely different aircraft further compounds the margin of error even more.

You trying to make a judgment on the validity of Mtt's design estimates off of such an ignorant comparison it is just plain silly.

All the best,

Crumpp

[Kurfürst]

Originally posted by gripen
I compared calculated performance of the G-1 to the flight tested performance of the G-5/AS. If we compare flight tested performance of the G-1 to the flight tested performance of the G-5/AS, the later is over 50 km/h faster at 10000m at same power setting..

[/B]

You also ignore that there was significant drag and weight difference between the G-1 and G-5 models that explans why the G-5 needs more power than the G-1 to get the same speed. Unless you claim the G-1 and G-5 was aerodynamiccaly the same, which of course they were not. The G-5 had worser cowling, wing bulges, weighted some 100-150kg more, and most importantly, it had non-retractable tailwheel.

Some G-1 and G-2 test results for you at 10km, 1.3ata :

Rechlin's tested G-1, 640 kph.
NII VVS tested G-2, 645 kph.

Originally posted by gripen
Butch has noted that he had problems to undestand the cryptic content of the report.

[/B]

Curious, I can't remember that, but I can remember he had said it's a flight test, which is supported by Soviet literature itself, and to qoute Carl-Frederik Geust's "Under the Red Star" the NII VVS got 650 km/h @ 7000 m from a Me 109G-2/R6, and 16 - 19 km/h more from a clean Me 109G-2 (W.-Nr. 14513).

I can't find any note about faulty supercharger from the report?

To qoute you :

"the Mtt tested Bf 109G did 626 km/h at FTH 6100m with the 1,3ata and 2600rpm. In the Erla set (13 planes), none of the planes reached 7000m FTH the average being 6700m and highest being 6900m (probably above spec rpm and/or below spec MAP). "

Moreover, the single Mtt tested G-1's FTH in climb was only 5500m, whereas the DB605A's static FTH was already 5800m.

The report is about compared the DB 601E and the 605A at the same powersetting btw (1.3ata) in the same airframe.. The DB 605A relates in output to the 601E similiarly as the 605AS relates to the 605A (in which case gripen argues it should be 50kph faster in a worser airframe), ie. nominally 1200 PS vs 1310 PS at 1.3ata, and much better at altitude.

Still, curiously, when the SAME airframe was tested with 601E, it reached 621 kph at 6000m.

When tested with the 605A, it only improved to 626kph at 6200m.

According to gripen analogy with the G5/AS, it should have reached at least 4-50kph more than with the 601E. Oops, that's exactly the same value the Soviets, Rechlin measured in flight tests, and Mtt calculated.

Based on "Gebläsedruck" curves supercharger actually seem to be give better than normal performance at low altitude. ..

[/B]

I don't think you understand what Gebläsedruck means.

Speed at 10000m is very normal for a tested G-1 or G-2..

[/B]

What is 'normal'? How do you decide what is 'normal'?

No, it's much lower than tested G-1 or G-2 tested by the NII VVS, or Rechlin, or Mtt calculations, or the official Kennblatt that was issued to inform pilots about the plane's performance.

It's from the NASM microfilms (I don't know which because I got these from other people), butch2k has a copy if you are interested. There is no details on tested planes but given the dates, these were probably G-1s.

[/B]

'Some NASM microfilms' - that doesn't helps much others the get idea of the test conditions, gripen. And I won't bug butch because of your claims. If you wish the fill your statements with credibilty, make the report clearly identifiable, or post it, send it via email, etc. Or just post the relevant conditions.

The tested plane weighed 3190kg in take off and it was a AS airframe ie no mg bulges. [/B]

The AS cowling also had MG bulges gripen. That cowling was still draggier than the G-1, and the non-retractable tailwheel (G-1s was retractable)is still there, not to say 3190 kg weight vs. 3047 kg of the G-1.

All in all, the G-5 airframe is at least 30-40kph draggier than the G-1 airframe at 10km altitude. The AS engine only made up for that. It's doesn't needs to be explained why a draggier plane needs more power to get similiar speeds.

It was some 50 km/h faster at 10000m than flight tested G-1s.

gripen [/B]

Your not is not very good, gripen.

Ie. the flight tested G-1s speed at 10km :

Rechlin's tested G-1, 640 kph.
NII VVS tested G-2, 645 kph.

You say the G-5/as was some 50 km/h faster than this, it means it must have reached some 690kph at 10km. Impressive, for a 30-min rating.

[Porta]

Kurfürst,

The Bf 109 G-1 Kennblatt data isn't corrected for compressibility. At 10 km TAS would be ~614 km/h.

This brings some questions about the soviet test, like what kind of performance reductions the soviets used or what were the conditions of the plane (manifold pressure reached, radiator flap position, etc).

Finally, you can get the sheet of Erla measurements (A/IV/64/43) from NASM Reel 2258, starting at Frame 430.