Spit/109 sea level speed comparisons in 1.08 beta patch

[Matt255]

And here is a perfect example of what I was refering to, that being how two people can read 'pilot accounts' and get different results

I think in that case, the pilots got different results.

Unless you really try very hard to make one plane appear better or worse than the other, ie abusing historical pilot reports to support your point of view. But who cares.

I generally base my idea of how these planes compared (maneuverability wise), on reports of pilots, who flew both (or more) types. And most of those reports fit each other exceptionally well. Which might not be the "correct" approach, but atleast it rules out some bias.

Originally Posted by Kurfürst

Because leading edge slats were fitted for exactly to this reason. Its no coincidence that slats cover the wing area ahead of ailerons, and maintain steady airflow without stalling at that part of the wing.

(sorry for cutting your post)

I'm totally aware of that and how slats work, but i don't think that's what macro meant when he compared slow speed rolling. But i probably misunderstood his post or interpreted it wrongly.

Anyway, yes, in the case you describe, slats definately help rolling and are in case of the 109 (lacking washout) a requirement for controllability at critically low speeds / high AoA.

So yes, the slats help, when they come out. Wether or not they are an advantage compared to washout or similar design features of a plane, regarding roll "performance", is a different thing though.

[bugmenot]

Originally Posted by 5./JG27.Farber

Well if we are using anecdotal and pilot accounts lets throw these into the fire:

http://www.virtualpilots.fi/feature/articles/109myths/

I stongley urge the red fliers especially to read this. Its a shed load of pilot accounts with sources, all about the 109 and what an Uber plane she really is!





I found this:

http://www.rolfwolf.de/daten/E4/Emil.html



I assume these are full throttle speeds.

Höchstgeschwindigkeiten in Steig/Kampfleistung (Tabelle)
I assume this is TAS

0km 460km/h

1km 480km/h

2km 500km/h

3km 520km/h

4km 540km/h

5km 555km/h

6km 555km/h

7km 550km/h

http://www.rolfwolf.de/daten/E4/Emil.html


Leistungen

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m





Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

[5./JG27.Farber]

Originally Posted by bugmenot

http://www.rolfwolf.de/daten/E4/Emil.html


Leistungen

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m





Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

I cant tell what your trying to say? - Just to add a graph? Mein Deutsch ist Scheiße

[ATAG_Dutch]

Originally Posted by 5./JG27.Farber

I cant tell what your trying to say? - Just to add a graph? Mein Deutsch ist Scheiße

Vielleicht kannst du im schule zuruck gehen? Never mind, so's mine.

[5./JG27.Farber]

services

Engine performance DB601A

Intermittent (1 min) 1100PS at 2400 r / min 1.4 ata

Start power 990PS at 2400 r / min 1.30 ata

Climb / combat power 910PS at 2300 r / min 1.23 ata

Full pressure altitude 4000m

Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

ok I got it. That graph is not full throttle but the limited combat setting and it also uses the old compressor which begins to loose Ata at 4500metres not 5000metres. Therefore the results are lesser than they should be in clod which seems to use the new compressor.

I wonder when the new compressor was rolled out into the field and at what rate?

[ACE-OF-ACES]

Originally Posted by Crumpp

He is not an aircraft performance engineer or an aerodynamicist.

Actually the graphs were done by an engineer..

Which is something I pointed out in the first response to this graph where I took the time to read and than quoted the graph's source, i.e.

Originally Posted by "The Most Dangerous Enemy" by Stephen Bungay

Turning circles are as calculated by John Ackroyd of the Manchester School of Engineering

Thus proving that humans (pilots, engineers, etc) can make mistakes..

As for the graph, as I initially noted, I questioned it's purpose..

Initially it seemed like it was done to give the impression that the 109 turn circles are far worse than the Spit and Hurri..

Which they well may be!

But, if that is the case this graph does not do a very good job of showing it!

It actually raises more questions and cast doubt for those who are use to looking at performance graphs (like myself)

If the purpose was to convey the turn radius (circle) at sea level than there is no need to provide an X (radius) vs. Y (alt) graph in that there is no X (radius) vs. Y (alt) taking place..

It is just X (radius) @ Y (alt)

IF that is the case, than placing 'Altitude (000ft) along the Y axis was wrong!

A better way to 'graph' this 'data' would have been to draw circles inside of circle with the radius associated with each circle and title the plot turn radius (circle) at sea level

[bongodriver]

like this one...

[ACE-OF-ACES]

Originally Posted by bongodriver

like this one...

Bingo!

Now looking at this graph..

We can see that the P51 and Spitfire both have a tighter turning circle (smaller radius) because their circles are inside the outer circle that

Also note, the outer circle (bigger radius) contains the the Bf109 along with the Tempest, Fw190, P47

The only info left off here is what is the speed and altitude?

Because these relationships can change with altitude

Also we can safely assume that this are the best turn circles at the best turn rates, but what is the rate?

Which is important, because what you really care about is the time it takes to do a say a 180 (reverse direction).

[Kurfürst]

There is no doubt that there is some sort of demonstrating our superiority ooze about these turn radii graphs... but regardless the figures seem to be about right.

It is entirely another question why this so called superiority is given so much importance. Even the graph shows that the turn radii difference between the Hurri and the 109 was about 200 feet, or about 60 meters. Even the span of these aircraft was 11-12 meters, and actually that's about the distance a 109 wingman kept from his leader... or even less. So what's all the fuss about it?

BTW the figures are rather similiar to what Morgan and Morris came up with in 1940 (for 12k feet - both figures are more of an educated estimate, not trials): http://kurfurst.org/Tactical_trials/...ls/Morgan.html

[ACE-OF-ACES]

Originally Posted by Matt255

I think in that case, the pilots got different results.

Maybe.. maybe not

The point being..

Two people can read a combat report and draw two different conclusions..

Due to their background and biases

Where as..

Two people can add 1 + 1 and draw the same conclusion.. i.e. 2

Independent of their background and biases

In summary..

The problem with anecdotical evidence (aka after action pilot reports) is as follows

1) anecdotical evidence is a one sided story.
2) anecdotical evidence is written by those who lived to write about it.
3) anecdotical evidence does not contain enough info to recreate the scenario in-game.
4) anecdotical evidence is subject to interpretation.

For example of each..

WRT 1) As most of us know there are two sides to every story, and you will not find anecdotical evidence that has input from both side (axis and allied pilot) with regards to the encounter being described.

WRT 2) As most of us know a statistical result depends on the input data. The fact that anecdotical evidence was written by the pilots who lived to write about it excludes the pilots who did not live to write about it. Which makes the statistical result based on the anecdotical evidence biased/filtered towards pilots who lived to write about it. For example, assume there are 100 after actions reports describing how the pilot in his 109 out turned a Spitfire.. We don't know how many 109 pilots died while trying to turn with a Spitfire a thus un-able to write about it, was it 10, 100, 1000? We don't know.

WRT 3) As most of us know anecdotical evidence does not contain enough information about the scenario to recreate scenario in game to preform a test to see if the results are the same. That and the results in both case (real and recreated simulation) depend more on the relative pilot experience than the relative plane performance. That is to say change the pilots and you can change the outcome of the scenario. In essence you would be making changes to the flight modeled based on the relative experience of the pilots not the relative performance of the planes. This is why they did testing under formal and controlled conditions. (see sig)

WRT 4) As most of us know people are different, and therefore peoples take on events will be based on their life experiences. That is to say two people can read the same anecdotical evidence and draw to very different conclusions. Ask any cop who has interviewed several people who have witnessed a crime and they will tell you how peoples perceptions of events can vary. Where as 1 + 1 = 2 is not open to interpretation. (math ftw)

PS in each statement above, there are no absolutes! To improve the readability, in this post I removed my previous qualifying text where I said things like 'typically this' or 'typically that' or 'you will be hard pressed to find'. That is to say, you may be able to find a couple of cases where both an axis and allied pilot had input to an after actions report, but this exception to the rule does NOT change the rule. Also note, I am not saying math is without error, only that math is your best hope of being on the same sheet of music, in that it removes most if not all human bias and interpretation errors. In short, given time, you can track down the source of math errors, where as even with all the time in the world you would still be hard pressed to track down the source of human bias and interpretation errors!