Bf-109 vs P-40

[Matt308]

Frankly, I would agree with you, Waynos. It is the rationale for those statements that get the peanut gallery in an uproar. And that is the point of this thread, is it not?

[JoeB]

Originally Posted by Vincenzo

that points were already show

Yes, and I took pains, twice, to state that the 325th's use of 'Hoimann' as a demonstrator for new pilots, to show them they could out turn the 109 in their P-40's was *not* the single killer piece of evidence that absolutely *proves* the P-40 could out turn the 109. Again as I mentioned the second time, responding to Timppa, 'turn' or 'out turn' is a less well defined concept than say, velocity where everyone means exactly the same thing whenever 'velocity' is mentioned. Not as true with 'turn'. All that said, IMO, and I said it was just my opinion, the 325th's experience with their captured 109G would weigh more heavily in my mind than graphs of unknown provenance.

Also in general on credibility of 'stuff you read on the internet', note that the post you responded to quoted the same info I gave from the same source as I did, the McDowell and Hess book on the 325th FG. The graphs just come from, well wherever they come from. That's not to disparage original efforts, but there is a difference between a 'trust me' source and pointing to a book or other record.

What's needed to verify a calculation (I'm also an engineer by training) is to show that it's predictions agree with full scale results over the whole range of applications in which you claim it's authoritative. It's not just to present 'the math' and effectively claim everyone who can't disprove that particular math must believe the calculation's accuracy. All engineering calculations are models of reality. Whether they model reality sufficiently for all the cases in which you use them is shown by agreement to full scale results.

Again I think a difference that creeps in here is that some people's aim is really to create a virtual reality for sim games which is well defined and predictable, and not wildly out of whack with the real world of WWII fighter a/c. Their goal is not really to fully explore the reality of WWII fighter a/c, with all its uncertainties and anomalies, which may just not be suited to a single answer. And sometimes that difference in goal shows.

Joe

[Matt308]

Well said.

[FLYBOYJ]

Originally Posted by JoeB

What's needed to verify a calculation (I'm also an engineer by training) is to show that it's predictions agree with full scale results over the whole range of applications in which you claim it's authoritative. It's not just to present 'the math' and effectively claim everyone who can't disprove that particular math must believe the calculation's accuracy. All engineering calculations are models of reality. Whether they model reality sufficiently for all the cases in which you use them is shown by agreement to full scale results.

Again I think a difference that creeps in here is that some people's aim is really to create a virtual reality for sim games which is well defined and predictable, and not wildly out of whack with the real world of WWII fighter a/c. Their goal is not really to fully explore the reality of WWII fighter a/c, with all its uncertainties and anomalies, which may just not be suited to a single answer. And sometimes that difference in goal shows.

Joe

From page 13 of the "parting gift."

4.1 Limitations of historical data

Generally, when dealing with historical performance data, there are several factors
to keep in mind:

• Aircraft performance is not uniform. Engines often have several percent
tolerance, and general condition of the airframe and surface finish can
make a difference, too. Power tolerances do not carry over linearly to all
performance parameters, they are less noticable in top speed, but more
pronounced in climb rate.

• Performance tests are always partially theoretical in order to determine
the performance of the aircraft under standard conditions for comparative
purposes. Atmospheric conditions, air temperature and engine performance
could vary in reality, so the test results had to be transformed
theoretically to stand for an idealized aircraft performing under standard
conditions.

• Real-world performance tests often contradict each other. Sometimes it’s
possible by using quantitative analysis methods to determine the reason
for the contradiction, sometimes it’s not. A lot depends on the level of
detail given by the historical reports.

• The engine charts historically used for generating idealized performance
charts are typically based on theoretical methods themselves. They are
usually accurate for the well-tested low-altitude region, but tend to be inaccurate
at higher altitudes. This is a reflection of the state of contemporary
technology: only the wartime pressure for higher engine performance
lead to a better understanding of engine physics towards the end of the
Second World War.

[Matt308]

...and this specifically:

"Real-world performance tests often contradict each other. Sometimes it’s
possible by using quantitative analysis methods to determine the reason
for the contradiction, sometimes it’s not. A lot depends on the level of
detail given by the historical reports.
"

... "A lot depends"? In a technical document? "A lot"? If the quantitative analysis has the merit to stand on it's own, then historical reports become irrelevant. If it cannot, then the quantitative analysis is subjugated to being only another data point for discussion. Not a fact. Just another data point for debate by the masses.

[drgondog]

Originally Posted by JoeB

e between a 'trust me' source and pointing to a book or other record.

What's needed to verify a calculation (I'm also an engineer by training) is to show that it's predictions agree with full scale results over the whole range of applications in which you claim it's authoritative. It's not just to present 'the math' and effectively claim everyone who can't disprove that particular math must believe the calculation's accuracy. All engineering calculations are models of reality. Whether they model reality sufficiently for all the cases in which you use them is shown by agreement to full scale results.

This is coincident with my own opinions on this subjet by theory and experience. well said Joe!

Again I think a difference that creeps in here is that some people's aim is really to create a virtual reality for sim games which is well defined and predictable, and not wildly out of whack with the real world of WWII fighter a/c. Their goal is not really to fully explore the reality of WWII fighter a/c, with all its uncertainties and anomalies, which may just not be suited to a single answer. And sometimes that difference in goal shows.

Joe

aero is complicated. I didn't spend 6 years in the academic side of the business and conclude that it was straightforward. It is a science and an Art... both structural and fluid mechanichs of a real airframe.

[Marcel]

Originally Posted by HoHun

Hi Les,

Well, here it is as a parting gift ...

Regards,

Henning (HoHun)

I hope you're not actually leaving, Henning, as I enjoyed your contributions.

[renrich]

Some comments from observers on the P40 during WW2: " The P40 was behind the times when introduced and never caught up. But it was the best available fighter at the time."
" The P40 could be very effective, and if well flown could even best an ME109 at low altitude."
" Stalin to Roosevelt, October 7, 1942: " It should be borne in mind that the Kittihawk planes do not stand the fight against present German pursuits."
" The primary disadvantages of the P40s were lack of range and altitude capability."
" No matter what we did we just couldn't make an ME109 out of a P40."
" The Germans in North Africa found that the P40 turned quickly and well against the ME109 while the latter was faster and climbed better. The German aircraft could intially dive more quickly as well,but in a long dive a P40 could catch a ME109."

[Njaco]

JoeB and others - I apologize if my post was redundant. I was trying to contribute after slogging through the previous posts. I neither on one side or the other but as I happened to have that book, I thought some passages would be a good addition. Sorry, Joe if it seemed like beating a dead horse.

[claidemore]

I like HoHuns graphs.
I don't always agree with them, I don't always interpret them the same, but I like them, and I appreciate how much work must go into making them. I know I can't make them.

The graphs I would like to see would be a comparison of the Spitfire Mk IX and XIV (18 lbs boost)to the 109G6 and K4 (1.45 ata).

I suspect those plottings would generate some discussion.

[Watanbe]

Whenever I read about the P-40 a common theme seems to appear. It seems that it was a plane that could get good results if flown by someone who really knew how to fly it. It the hands of an average, inexperienced pilot it wouldn't be able to compete with a Me-109 on an even level.

[FLYBOYJ]

Originally Posted by Watanbe

Whenever I read about the P-40 a common theme seems to appear. It seems that it was a plane that could get good results if flown by someone who really knew how to fly it. It the hands of an average, inexperienced pilot it wouldn't be able to compete with a Me-109 on an even level.

I think that's the message many of us were sending here....

[Watanbe]

Probably should of read the whole topic then

[FLYBOYJ]

Originally Posted by Watanbe

Probably should of read the whole topic then

No worries

[Juha]

Hello
According to Soviet tests time to make 360deg turn at 1000m: Bf 109F-4 20,5 sec, Bf 109G-2/R6 (with 20mm underwing gun gondols) 23sec, Bf 109G-2 21sec.
Curtiss P-40C 18sec, P-40E 19,2 sec.

Juha