Ivanov fighter statistics

[spicmart]

Anybody know about this? It's the first Time I see this. Some interesting findings there.
Engineers Konstantin Ivanov and Vladimir Georgiev from a University of Sofia went to scientifically calculate performance stats of WW2 planes and compared it to those found in the works of William Green and Chris Chant.
Here I have a chart for the most important European important fighters:

Here is a site with more information about this work and lots more of aircraft stats.
It's only in German but maybe you can use some translator:

Flugleistungen der wichtigsten Flugzeuge - Luftkrieg über Europa 1939 - 1945: Die Angst im Nacken

 

[Shortround6]

I would view the "maximum climb rate (continuous accent)" with a large dose of skepticism.

The "continuous accent" description being the problem as many of those aircraft were rated at a 1/2 hour or one hour power rating for continuous accent and not a 15 minute or 5 minute rating (1 minute ratings being rather useless for climb)
I doubt very highly that the 109K was using a 1 hour rating to climb at 4980f/m.
climb to 6000 meters in just over 4 minutes anyone?

 

[GregP]

I'd bet P-51D pilots who could catch a Bf 109 at 20,000 feet would be very surprised to learn the Bf 109 actually faster than they were ...

Let's see, the DB 605 made about 1600 PS (1578 hp) on B4 fuel, with MW50 at 6000 m, and 1,160 PS continuous power. 1,850 PS at takeoff at 1.8 ata. If MW50 was not available with the B4 fuel, the boost was limited to 1.45 ata, and it made considerably less than 1578 hp. On C3 fuel, it could make 2000 PS at 1.98 ata when using MW50. There was not a lot of C3 near after summer 1944 (well, at the airfields, anyway ... especially the forward ones), and MW50 was a very short-duration thing. So, it was basically a 1600 PS engine for short duration.

So, the Bf 109K had about 3/4 of the power loading of the P-51D at sea level (in pounds per hp), yet we see Ivanov expects the Bf 109K to climb at 2.8 times the rate of the P-51D at 20,000 feet? Never mind that the BD 605 was a single-stage supercharger and the P-51D had a 2-stage supercharger. I have also never seen a P-51D that had a climb rate of only 2,441 feet per minute unless it was being cruise-climbed at reduced power. Last time I rode in one, we climbed at that rate on GREATLY reduced power, not max continuous or WEP. And we were turning significantly less than 3,000 rpm while doing so.

It may seem like I am trashing the DB 605. Not so. It was and IS a good engine, assuming short TBO is not an issue. But it wasn't going to last very long on MW50, and would be back to startingly normal power ratings in a short time. It would be useful to compare the expected performance numbers at military power only, not assuming absolute maximum power output that could not be maintained for long. When I quote P-51D performance numbers, it is not usually at WER power. A climb rate you can hold for only 5 minutes is not very representative of an aircraft's expected performance in combat.

I notice all the German planes are calculated by Ivanov at or above their often-quoted speeds, while all the Allied aircraft don't seem to fare as well versus the often-quoted numbers. Either we have great PR departments or our engineers are somehow a bit off in their numbers. Perhaps he is calculating the performance of P-51D aircraft in Soviet service using Soviet-supplied fuel and Soviet maintenance? That might explain some of the discrepancies. I can't tell from the post and have no knowledge of Ivanov's qualifications to calculated his grocery bill, much less aircraft performance numbers.

I'll go out on a limb and assume he knows a thing or two about it. But, if so, why are his numbers so much lower for Allied aircraft than our own performance tests show? It would be interesting to find out a few things about his assumptions and methodologies before additional comment.

 

[Schweik]

Curious Ta-152 is listed as one of the important aircraft types of the war seeing as how few were actually ever in combat....

 

[tomo pauk]

Anybody know about this? It's the first Time I see this. Some interesting findings there.
Engineers Konstantin Ivanov and Vladimir Georgiev from a University of Sofia went to scientifically calculate performance stats of WW2 planes and compared it to those found in the works of William Green and Chris Chant.
Here I have a chart for the most important European important fighters:

Some items of the table do raise eyebrows, like listing the 109K-4, 190D-9 and Ta-152 as from mid-1944 - nope, they were not in use that early. Then we have a thing where table is not composed by data found on primary sources, but from secondary sources. I've taken a look at tables from the linkes article, where the author puts P-51B&D dive speed at 750 km/h, and of the P-47D at 825 km/h. The Ta-152 going almost 490 mph, the 190A-8 (slowest of the Antons) going 660 km/h?? The renown 'turner', Spitfire, somehow can't out-turn the German opposition? We have a lot of data for Merlin Mustangs making 445 mph (test reports etc.), yet somehow they are much slower here.
Then - why choosing a specific altitude where the 109K-4 is supposed to excel and then compare other fighters with it?

So again, just putting the late 1944/early 1945 German fighters in the table that deals with mid-1944 fighters in service is IMO enough to disqualify it as something reliable.

 

[Luft.4]

A strange compilation of speeds indeed. The author has the Bf 109 G-14 clocking 699km/h. I have yet to find any original documentation of that model flying that fast even with boost engaged!
See attached WIP graph complied from original German docs.
All the best,
Dan.

 

[Denniss]

by far too slow for a G-14, the curve is non-standard for a DB-engined 109
The G-6 achieved a similar speed on emergency without MW50

 

[Luft.4]

The G14 was a modified G6 with the same engine, performance is within the same ballpark. DB605AM. Boost performance is better on the G14, without boost the 2 fly pretty much the same. In fact the G6 MW50 was the original G14, so the close performance is to be expected. Figures are correct, taken from German docs. The 5 January 1945 issue of aircraft performance, 3rd edition, states similar values.
Real performance difference are noticeable only in the G14/AS, then the G10 and K4.
The author of the book this thread is about seems to have gone for calculated values derived post war rather than German documents. As stated in the above comments, there are many strange remarks regarding aircraft performance which does not coincide with documented facts from archives.
All the best,
Dan.

 

[GregP]

Planes of Fame Air Museum operates anywhere from three to seven P-51s. We fly a P-51A, two P-51Ds, and have Strega and Voodoo in our stable in addition to frequent visiting P-51s, mostly P-51Ds, including the Bardahl Special, winner of the last Reno race. We get better than his maximum ascent climb rate at considerably reduced power on stock warbirds ... never mind max or WER power or power from a racing engine. If you aren't racing, nobody runs a race engine! Even Strega or Voodoo get a stock Merlin for relocation flights. The racing engines are exactly for that - racing

Our Allison-powered P-51A made 360+ mph around Reno's 8-mile oval race course loop pulling several g's. Even it will beat 396 mph in a straight line.

Methinks his calculations are pretty conservative with regards to Allied airplanes. Not too sure why he would think the Bf 109 would outclimb a Spitfire XIV, but all you have to do is fly them next to one another to dispel that myth. We have. The Bf 109K was a decent leap in performance over the Bf 109 typical G-model and accounted for about 5.5% of the wartime production, many of which never saw action. Not too sure why it would qualify as an "important" warplane since it didn't see a lot of service. Ditto the Ta 152, which had virtually zero wartime impact. Let's see, it shot down anywhere from 7 to 10 Allied aircraft for the loss of 2 to 4 Ta152s.

In a war where the Germans accounted for more than 66,000 claimed victories, why in the world would the Ta 152's 7 to 10 victories even merit a footnote that it existed in the first place? It was impressive, but totally pointless with regards to wartime military action. Yes, it would have affected future piston fighter aircraft if it weren't for that pesky jet engine that relegated them all to retirement except for the mighty Skyraider.

We used to operate a Spitfire IX and a Mk XIV. Their performance was sparkling compared with most other WWII fighters, and our Mustangs make better than book numbers at book weights, when we get them that heavy. Don't get me wrong, we don't go out and test maximum speeds these days. But we cruise better than book numbers. By "cruise better," what I mean is we typically can cruise at book speeds on less manifold pressure than the book calls out for a particular speed and rpm. When we elected to go around Reno with stock warbirds, we got better than expected speeds.

Last, the "we" above is not me, Greg. It is regular Planes of Fame pilots running Planes of Fame airplanes or dedicated racing airplanes on supplied Reno fuel. Stevo Hinton won Reno in Strega, Voodoo, and the Bardahl Special, none of which are exactly anywhere within a light-year of being "stock" warbirds. But Wee Willy and Spam Can both make or exceed book numbers and are both very stock airplanes.

So, I suppose you need to consider the source when you decide what to believe. They don't call the manual numbers "book numbers" without a good reason for it. I would not say "bunk" to many reports, but this one seems like an attempt at trolling the forum to see if anyone is gullible enough to bite. Perhaps it is more of an "entertainment" post? Or just a way to start an argument.

I'd say to you, let's not bite the hook! There are about 80 years of warbird operation experience that say whether or not warbirds make claimed performance. Very largely, they do.

 

[Luft.4]

If you are talking about the first post when you write "this one seems like an attempt at trolling the forum to see if anyone is gullible enough to bite", I believe the original poster just noticed some stark differences and wanted an extra opinion. Nothing wrong with that.
Totally in agreement that some of the book's figures are questionable.
All the best,
Dan.

 

[GregP]

I was not talking about the first poster, even though it possibly seems that way when I re-read it. So ... no, NOT OP.

I was talking about the calculated numbers that seem to fly in the face of multiple test results from multiple agencies in different countries that all basically agree with one another, including tests from both Allied and Axis test agencies for the same airplane types.

I've ridden in a P-40N that exceeded the maximum continuous climb rate quoted above for the P-51D, and we all KNOW a P-51D will handily out-perform a P-40N.

I've also ridden in a pristine P-51D that ALSO considerably exceeded that climb rate at less than full power.

So, perhaps you can understand if my skepticism is alive and well with regard to the numbers quoted above.

 

[Shortround6]

WW II combat aircraft were supposed to loaded to certain weight, or ballasted to reach that weight. The idea was to get an idea of what the plane could do in operational condition (guns, ammo, at least enough fuel to fight and get home and maybe a few extras? life raft for overwater flights?)
Condition was sometimes noted, rough or worn paint or other problems.

A 6 gun P-40 held about 420lbs of ammo. the six guns went around 470 lbs. The original radios could go around 120-130lbs (some exceptions). Modern warbirds are using what kind of fuel tanks/fuel cells?

Now a problem with calculated figures is trying to include everything in the calculations. Or using a figure from one airplane on another plane and figuring it is close. Rear view mirrors, steps/hand holds, antennas and so on. I, for one, have never found out the difference in drag between the landing gear on a P-36 and the landing gear on a P-40. Even the P-40Q with a speed in the lower 400s stayed with the fully exposed wheels. Were they dumb or did they know something (from wind tunnels or flight) that is not published?

Granted we can do a lot better modeling of airflows in computers than they could do back then (wool tufts in wind tunnels?) but we have to put in good data to get good data out or GIGO.

 

[Denniss]

The Bf 109 G-14 was capable of reaching 665 km/h at 5km altitude. That zig-zagging line is not made with a standard supercharger using its hydraulic coupling

 

[Luft.4]

If one uses the GL/CE-2 data then yes. That much is lacking in this WIP graph. Both figures not being close to 699 km/h is also true. If we keep looking at GL/CE-2 figure, say for the G6 , max speeds are 650. If we want to view it as the OKL did back in 1945, we can use the figures from the OKL.
If one wishes to factor in the poor quality of Luftwaffe aircraft by the end of the war, as noted in many reports, 665 becomes a stretch as well. WIP graphs are meant to be worked on and I'm trying to find a balance between test figures, official OKL figures (ex from 5 January 1945) which was how the Luftwaffe saw it, and reports of aircraft being up to 40km/h slower due to poor build quality (see AIR40/47 ADI(K) No. 417/1945, p.9).
Most graphs do not show the lag from the supercharger coupling changing gears, which only exacerbates a drop in performance. This does not mean the engine configuration was any different, it only means they did not graph the drop in speed accurately when the gears switch.

All the best,
Dan.

 

[GregP]

The reason they didn't graph the supercharger change is pretty simple.

If you are out flying and the supercharger changes gears, then the momentary drop in performance is unimportant.

If you are somehow involved in combat right then, you would not leave the supercharger in Auto, but would rather switch to low or high manually so you would NOT have the momentary drop. Instead, if you were climbing or descending, you'd pick your place to change supercharger gears rather them leave it to the automatics, that is ... IF the momentary drop was important to you.

If not, then you'd just leave it in Auto mode.

So, it would be pilot's choice to lave it auto or make a manual selection. The only time it would be important is if it happened right when you were shooting at someone or right when you were trying to escape someone shooting at you.

With MY luck, that would be in every combat! Mostly, in the real world, it wasn't an issue.