109 sustained turn performance

August 18, 2020

9 hours ago, Holtzauge said:

Frankly @Panthera, how do you come up with Clmax=2 power on for Me-109? The way you framed it now looks more like a value you would like to see and something simply pulled out of a hat because I don’t see anything supporting that number at all.

You just asked me for a ballpark figure...

And what do you mean you see nothing supporthing this figure? What supports a lower figure?

To me a power on CLmax of ~2.00 at 1 G is a completely sensible ball park figure for such a slatted wing configuration. As speed & G increases this figure goes down, as it does for all aircraft (power off or on).

9 hours ago, Holtzauge said:

In addition, if I were to use your higher estimates on Clmax for the Me-109K4, I would get better than historical numbers not only for the K4 but for all Me-109 that I have modeled so no sale.

What historical figures are you talking about? AFAIK there are no historical figures on turn rate.

And yes, ofcourse if you're using an incorrect CLmax figure then you will get incorrect results, that's a given.

9 hours ago, Holtzauge said:

Also cherry picking the highest number available for the Me-109 from the Chalais Meudon wind tunnel tests does not exactly strengthen your case: The results were 1.42, 1.45, 1.44, 1.42, 1.44, 1.48, 1.43 and 1.45. Taking the average of these we get instead 1.43 not 1.48 so picking the highest available number puts a dent in your credibility TBH.

I asked, I didn't cherry pick. If the average was 1.43 I am perfectly fine with accepting this, 1.48 was merely what a quick google search resulted in. That said how did this wing differ from the one on the production aircraft? Was it the same shape? Did it possess slats etc? Asking as I see people say it's for a shorter wing without slats.

Also I'd say attacking another forum member for doing nothing but obliging your requests is more of a credibility hit. I really don't understand this sudden mood swing.

Quote

Thinking back I remember I have had this exact discussion back in 2014 in the DCS forum: A guy using the handle Hummingbird made a remarkably similar case to yours in this DCS thread.

Ok... Are you saying I'm this guy now?

Really not sure what I did to deserve all these ad hominem attacks Holtzauge, I thought we were on a similar mindset here. I'm taken aback I must say.

Quote

One nice aspect of that discussion in DCS though, was that the DCS FM developer Yo-Yo participated in the debate and I would say that Yo-Yo and I landed very much on the same page regarding Hummingbird’s and Crumpp’s wish to jack up the Clmax for the Fw-190D9 and Me-109K4, as in no sale.

Well I love the way all three aircraft are simulated in DCS, it's the most accurate representation I've ever experienced of these warbirds, as I've told you several times already. Infact like I said before I tested both in DCS not so long ago, and the sustainable G at 200 kts (seal level), is 3.0-3.1 for the P-51 vs 3.6-3.7 for the K4, both at 400 Liters of fuel. Which is about what I get for both aircraft as well, so the developer "Yo-Yo"? and I are completely on the same page as far as I'm concerned.

9 hours ago, Holtzauge said:

Attached below is a chart from that discussion which was done more to compare the Fw-190D9 and P-51D carrying the same fuel load so the Me-109K4 looks a bit better in that since it’s carrying a smaller fuel load. So in order to compare apples with apples, I did another C++ simulation just now for SL conditions assuming the P-51 and Me-109K4 carry the same fuel load 290 l and for that I get the exact numbers [TLC]MasterPooner mentioned above: For the 109 K4 18.48 s at 1.8 ata and for the P-51D 19.50 s at 67" boost.

No you didn't get the exact same numbers, you got a 1 sec difference, not a ½ sec difference. Which is not the case in IL2, and why I started this thread.

In short your own estimates don't agree with IL2 either, they lean more towards my own position. Now if we disagree on the Clmax figure, then so be it, it aint the first time, but let's keep it civil atleast.

Edited August 18, 2020 by Panthera

August 18, 2020

Okay, I have a basic test methodology down now, and a spreadsheet and procedure which I will share later with the recordings. Managed to get four sustained turns one after another on a very accurate run using 100% fuel, 1.8 ATA and DB engine. By using a positional reference on the ground and a stopwatch to judge accurately the start/end of the turn, first data shows:

Average turn time @ 400 km/h (IAS) and 1km altitude: 23.58 seconds.

It's probably going to take a while to collate a long string of data of different speeds and train myself to keep precise altitude and speed to the accuracy we're looking for, but it's a start.

Will try the same but 290 litres as well - just once or twice for comparative purposes to see the difference.

Edited August 18, 2020 by Aurora_Stealth

August 18, 2020

1 hour ago, Floppy_Sock said:

More data in more situations will come. The testing is slow and arduous because we don't have access to the necessary telemetry and need to record each data point by hand. We're just getting things rolling in terms of testing more thoroughly. This is the only data set I have on hand for those birds atm unfortunately.

Can you shed some light on what your simulations entail. When you say simulation, are you actually simulating flow?

If so, can you provide some rough outline (the more detail the better):

Dimensionality, assumptions, method(finite difference, volume, element, collocation etc)

Or are you using empirical coefficients - if so could you provide some of them and their references? I'm always hunting for more data.

If the latter is the case, I'm quite curious since your data indicates that lift limit for the p51 is actually somewhat better, even at low mach number. This is somewhat contradictory to the data I've seen for the p51 (I don't mean to call you out here or claim you're making a mistake, more that I probably don't have good resources on hand.)

Thanks!

Here's the P-51's Clmax vs mach compared to that of aircraft with a more conventional type airfoil (Source: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930084610.pdf)

As you can see the laminar flow airfoils do gain an advantage above 0.5 mach (a desirable trait for a jet), but below that it is noticably lower, and that is due to the sharp leading edge not being ideal for lift production at these lower speeds. Modern jets overcome this with the use of LE slats or flaps.

Edited August 18, 2020 by Panthera

August 18, 2020

7 hours ago, Holtzauge said:

However, I see another issue with the current Me-109 FM: My impression is that it suffers too much drag when you go slow or alternatively when you pull high angles of attack and IMHO it seems like the Me-109 suffers more from this than it should but I have yet to figure out a good way to show that. To me it seems that if you go to slow in the Me-109 in-game and get "behind the curve" as in a low speed high angle of attack state, it takes more time and effort to get back energy than it should. I have discussed this with @ZachariasX (has from the Spitfire TR-9) who has the same opinion.

When I read this I am even more astounded by your replies towards me, because that was the same suspicion I aired in the thread opener.

Edited August 18, 2020 by Panthera

August 19, 2020

7 hours ago, Holtzauge said:

Edit: I saw the IL2 specs you just added for the K4 and that 24 s at SL number has got to be a typo: I remembered there was something like that before as well for another aircraft in the aircraft descriptions and they updated it. However 24 s is the right number for the K4 at 3 Km altitude so that could have been it.

According to the Tech Specs page, (K-4)

Note 3: maximum speeds, climb rates and turn times are given for standard aircraft mass.
Note 4: climb rates and turn times are given for Combat power.

Engine modes:
Nominal (unlimited time): 2400 RPM, 1.35 ata
Combat power (up to 30 minutes): 2600 RPM, 1.45 ata
Emergency power (up to 10 minutes): 2800 RPM, 1.8 ata

Standard weight: 3361 kg

Do you get 24 secs using these numbers?

August 19, 2020

16 hours ago, Floppy_Sock said:

More data in more situations will come. The testing is slow and arduous because we don't have access to the necessary telemetry and need to record each data point by hand. We're just getting things rolling in terms of testing more thoroughly. This is the only data set I have on hand for those birds atm unfortunately.

Can you shed some light on what your simulations entail. When you say simulation, are you actually simulating flow?

If so, can you provide some rough outline (the more detail the better):

Dimensionality, assumptions, method(finite difference, volume, element, collocation etc)

Or are you using empirical coefficients - if so could you provide some of them and their references? I'm always hunting for more data.

If the latter is the case, I'm quite curious since your data indicates that lift limit for the p51 is actually somewhat better, even at low mach number. This is somewhat contradictory to the data I've seen for the p51 (I don't mean to call you out here or claim you're making a mistake, more that I probably don't have good resources on hand.)

Thanks!

The C++ program I use is not CFD but a parameter based simulation and an adaptation of a program I originally wrote for my master’s thesis to study the effect of external stores on jet aircraft but about 15 years ago I adapted it to also handle prop aircraft. As an example, Clmax is a function of Mach as is Cdo so I can capture subsonic drag rise and compressibility effects. Propeller efficiency is a function of blade loading, advance ratio and blade tip Mach number. Oswald factor is a function of Cl etc.

For the P-51 I currently assume 1.4 as low Mach Clmax based on NACA report 829 which gives Clmax 1.44 for the Mustang (Airplane 1 in the report) in pristine sealed conditions and 1.4 as Clmax with in-service roughness. Then as I mentioned above, Clmax goes down with Mach in the code and for example, at M=0.5 I’m down to a bit over 1 in Clmax.

When it comes to exactly how the simulator works I’m not going to divulge that here since I’ve spent years collecting the data I use and I’m working on a book project so I’m not ready to undercut my market just yet . On a more serious note: I have been posting results for more than 10 years in various forums and you have to judge the results I produce in exactly the same way you do flight sims: No one posts trade secrets and you have to look at the results for tested/simulated scenarios, compare that to historic data or what you think the results should be, and then make up your own mind if you think the simulation is any good.

That being said I for sure want to discuss the assumptions going in (like Clmax) so if you have an interest in this and have collected data as well that sounds good.

15 hours ago, Aurora_Stealth said:

Okay, I have a basic test methodology down now, and a spreadsheet and procedure which I will share later with the recordings. Managed to get four sustained turns one after another on a very accurate run using 100% fuel, 1.8 ATA and DB engine. By using a positional reference on the ground and a stopwatch to judge accurately the start/end of the turn, first data shows:

Average turn time @ 400 km/h (IAS) and 1km altitude: 23.58 seconds.

It's probably going to take a while to collate a long string of data of different speeds and train myself to keep precise altitude and speed to the accuracy we're looking for, but it's a start.

Will try the same but 290 litres as well - just once or twice for comparative purposes to see the difference.

OK, for 100% fuel 400 Km/h IAS at 1 Km 1.8 ata I get 22.5 s but as I said earlier, I think the main issue could be the low speed induced drag/propeller efficiency combination starting from say 300 Km/h IAS and below.

9 hours ago, unreasonable said:

According to the Tech Specs page, (K-4)

Note 3: maximum speeds, climb rates and turn times are given for standard aircraft mass.
Note 4: climb rates and turn times are given for Combat power.

Engine modes:
Nominal (unlimited time): 2400 RPM, 1.35 ata
Combat power (up to 30 minutes): 2600 RPM, 1.45 ata
Emergency power (up to 10 minutes): 2800 RPM, 1.8 ata

Standard weight: 3361 kg

Do you get 24 secs using these numbers?

At that weight I get 21.3 s at SL and 26.5 s at 3 Km with Steig&Kampfleistung so I’m still thinking that there may be a typo in the IL2 spec sheet. OTOH this should be easy to test in game: In the current release, if you test under these conditions do you come close to the numbers I posted or do you come closer to 24.2 and 32.3 s ?

Edited August 19, 2020 by Holtzauge

August 19, 2020

On 8/18/2020 at 1:51 PM, Aurora_Stealth said:

In fact you have just strengthened our case further by dismissing someone who is clearly very experienced on the matter - if not one of the best authorities we could have hoped for on the matter.

Totally agree with Skip Holm's credentials, but if you want to give us the benefits of Skip Holm's experience why not share an interview where he is not clearly hyping up his pet plane. It is unfair to cite this sort of interview as something to base anything off. It's just pub talk, basically.

Especially as he's saying stuff which contradicts actual tests.

Edited August 19, 2020 by 71st_AH_Barnacles

August 19, 2020

9 hours ago, 71st_AH_Barnacles said:

Totally agree with Skip Holm's credentials, but if you want to give us the benefits of Skip Holm's experience why not share an interview where he is not clearly hyping up his pet plane. It is unfair to cite this sort of interview as something to base anything off. It's just pub talk, basically.

Especially as he's saying stuff which contradicts actual tests.

Well I'd love to, but there aren't many videos available of Skip Holm talking about the '109, I think there is a website with some of his details about it and some footage of him flying it.

On that same basis we could effectively dismiss the entire USAAF pilot accounts of WW2, seeing as most of them involved wild over-claiming based on "hyped up pub talk" in their accounts. I think we both know that's going a bit far. Not sure which tests you are referring to?

I'm not suggesting you base anything off just one pilot account... its there for adding some relevant context to the discussion. If there is a consensus universally among experienced warbird pilots... and they all say they feel very confident about engaging heavier aircraft like the Mustang (similar argument would apply to the Tempest) with superior turning performance in the Bf 109 at low speeds - you do have to ask why they are saying that.

As a side note, was reading the last pages of 'The Big Show' by Pierre Clostermann last night. He was running one of the Tempest squadrons from December 1944 and he provides some insights into the aircraft, I came across this very relevant passage regarding the Bf 109 K / Tempest that I felt was worth sharing here. He clearly was well informed about the Bf 109 K as he specifically knew some batches were initially built with a wooden tail stabilizer, and he specifically mentions and reminds his pilots in combat about the maneuvering speed which he felt was disadvantageous to the Tempest.

As a disclaimer (do i really need to say this?): Please do not not take single accounts at absolute face value, these contain opinions and subjective content and are posted here for contextual reasons for the sake of this discussion.

Edited August 20, 2020 by Aurora_Stealth

August 19, 2020

One of the best turning planes in BoX series and ppl with 109s as their profilpic be like "muh 109 has drag somewhere!!!!!!! IT SHOULD OUTTURN SPITFIRES!"

BRUH

August 19, 2020

9 hours ago, Holtzauge said:

The C++ program I use is not CFD but a parameter based simulation and an adaptation of a program I originally wrote for my master’s thesis to study the effect of external stores on jet aircraft but about 15 years ago I adapted it to also handle prop aircraft. As an example, Clmax is a function of Mach as is Cdo so I can capture subsonic drag rise and compressibility effects. Propeller efficiency is a function of blade loading, advance ratio and blade tip Mach number. Oswald factor is a function of Cl etc.

For the P-51 I currently assume 1.4 as low Mach Clmax based on NACA report 829 which gives Clmax 1.44 for the Mustang (Airplane 1 in the report) in pristine sealed conditions and 1.4 as Clmax with in-service roughness. Then as I mentioned above, Clmax goes down with Mach in the code and for example, at M=0.5 I’m down to a bit over 1 in Clmax.

When it comes to exactly how the simulator works I’m not going to divulge that here since I’ve spent years collecting the data I use and I’m working on a book project so I’m not ready to undercut my market just yet . On a more serious note: I have been posting results for more than 10 years in various forums and you have to judge the results I produce in exactly the same way you do flight sims: No one posts trade secrets and you have to look at the results for tested/simulated scenarios, compare that to historic data or what you think the results should be, and then make up your own mind if you think the simulation is any good.

That being said I for sure want to discuss the assumptions going in (like Clmax) so if you have an interest in this and have collected data as well that sounds good.

OK, for 100% fuel 400 Km/h IAS at 1 Km 1.8 ata I get 22.5 s but as I said earlier, I think the main issue could be the low speed induced drag/propeller efficiency combination starting from say 300 Km/h IAS and below.

At that weight I get 21.3 s at SL and 26.5 s at 3 Km with Steig&Kampfleistung so I’m still thinking that there may be a typo in the IL2 spec sheet. OTOH this should be easy to test in game: In the current release, if you test under these conditions do you come close to the numbers I posted or do you come closer to 24.2 and 32.3 s ?

I've seen your posts a few times now looking back. I appreciate you sharing your methods a bit - no need to indulge more on those. I've written my fair share of CFD simulations - I'm well aware of the enormous effort it takes writing your own. Kudos. Wish my work was more applicable here

Thanks for the source - I went back to the report that was mentioned above by Panthera, I realize I remember the high alt data not the data from SL. See figure 6 in the naca TN 1044 (https://ntrs.nasa.gov/citations/19930084610) P51B was waxed, polished, power off - similar to the report you posted.

Do you happen to have any power on lift data for these birds?

I have plenty more questions but as to not derail the original discussion, this isn't the place to ask - maybe some other time.

Thanks

Edited August 19, 2020 by Floppy_Sock

August 20, 2020

Here's the data recorded for the Bf 109 K-4, takes quite a lot of concentration and time to keep IAS and altitude both exactly within limits (4% tolerance of target IAS / altitude).

Average figures seem to show the general pattern. That's about as accurate as I can get without taking a much larger sample size and spending considerably more time. Don't have more time to give this at the moment. Obviously if anyone has better test setup then by all means go ahead.

I've done a comparative sample using the requested 290 litres fuel load as well but didn't show much difference, however this is a small dataset so not a big surprise.

Hopefully some of the data is useful for the calculations / CFD simulations. It's 2am in the morning here so will upload the test recordings for reference tomorrow (having issues with file type and upload limits even using .zip files).

6 hours ago, PikAss said:

One of the best turning planes in BoX series and ppl with 109s as their profilpic be like "muh 109 has drag somewhere!!!!!!! IT SHOULD OUTTURN SPITFIRES!"

BRUH

lol, no one here is suggesting that it out-turns Spitfires - that's been put to bed a long time ago.

Edited August 20, 2020 by Aurora_Stealth

August 20, 2020

Sorry guys, but turn times of 21-23 seconds for the 109 K-4 1.8ata autumn settings, are simply wrong.

Full fuel 1.8 ata:

Sustained turn rate 18.5 degress per second, or 19.5 second turn times. Sustained turns are starting at the yellow line. I measure the turns using both the turn rate indication in taciew and by checking the heading in taview and timing how long it takes to come around. Both give the same result.

This is an example 19 second turn, really 19.5 but due to measuring whole seconds it comes out as 19. Some of the turns measured this way came out at 20 seconds.

Here is the K4, same settings, at 50% fuel:

Turn time, 18.65 seconds. Turn rate 19.3 degrees per second.

P-51 D 67 inches, 25% fuel:

Turn time: 19.35 seconds Rate: 18.5

(yellow line denotes sustained turns once sustained speed was reached.) Inconsistencies in the graph wave are me getting into the sustained turn.

It should now be obvious from the much higher times given by several people in this thread, ranging from 21-23 seconds that the problem here is piloting, not that the 109K in game is not more agile than the P-51. You guys are not even close to being in the right ballpark in numbers that have been given for in game performance. This is accounted for easily by the fact that the Bf109 is much harder to fly than the P-51 is, owning to it being a very small plane with a huge amount of power that lacks proper trimming abilities. This means that flying it to max is harder since you have both higher levels or torque and no ability to fight it except with stick inputs.

I did these tests a year ago and got the same results.

Edited August 20, 2020 by [TLC]MasterPooner

August 20, 2020

I haven't been following the debate very closely, but it seems that these two tests were done under somewhat different conditions (~280 km/h, sea level, autumn vs 300-400 km/h, 1000 m, summer). Also, the measurement methods seem very different and the results do have quite a large variance between individual runs.

Could these things partially explain the different results? I think it's important to perform the same test before blaming piloting skills.

Edited August 20, 2020 by Mitthrawnuruodo

August 20, 2020

3 hours ago, Mitthrawnuruodo said:

I haven't been following the debate very closely, but it seems that these two tests were done under somewhat different conditions (~280 km/h, sea level, autumn vs 300-400 km/h, 1000 m, summer). Also, the measurement methods seem very different and the results do have quite a large variance between individual runs.

Could these things partially explain the different results? I think it's important to perform the same test before blaming piloting skills.

Yes that is part of it. Although more than one person posted their tested times. The other test that was posted is done during summer instead of autumn, autumn being standard day conditions IIRC. Summer will make performance worse. But the other large test was done using arbitrarily turn speeds instead of letting speed drop to sustained turn speeds.

3 hours ago, Mitthrawnuruodo said:

I think it's important to perform the same test before blaming piloting skills.

Several people posted results or made assertions about relative in game performance. It is also a piloting problem if the perceived sustained speed is completely off the mark.

Somewhat outside of this thread, I see this happen all the time in MP. Both in duel and just regular MP sorties. I generally detest the "git gud" accusations that are made in forum debates about game "realism," but this is one particular claim that has been coming up over and over again in the community and there have always been large disconnects between the claims of in game testing performance and the actual reality. I cannot tell you how many times I have been in duels with 109Ks on the deck and watch them massively under perform the plane. Frequently it results in them cartwheeling to the ground after spinning out after several turns. Despite how this might seem, this is not gloating. There are many pilots in this game better than I am, I have simply seen this happen so much in the last year that I think it is the cause of these claims. And the fact that the other numbers being suggested are completely in left field proves that so far as I am concerned.

There are several obvious reasons this perception exists:

-the turn performance between the planes is close.

-the 109 has more torque

-the 109 has no trim except in pitch

-the P-51 has a G suit

-the P-51 has a better flaps system that allows it to drop flaps to get a momentary turn rate spike, then raise them again to get rid of the drag once speed drops. 109s are too slow to do this.

Edited August 20, 2020 by [TLC]MasterPooner

August 20, 2020

7 minutes ago, [TLC]MasterPooner said:

But the other large test was done using arbitrarily turn speeds instead of letting speed drop to sustained turn speeds.

There is no single "sustained turn speed". Sustained turns can be performed at an arbitrary speed. "Sustained" only means that speed and altitude are maintained during the turn.

August 20, 2020

3 hours ago, Mitthrawnuruodo said:

There is no single "sustained turn speed". Sustained turns can be performed at an arbitrary speed. "Sustained" only means that speed and altitude are maintained during the turn.

Nope. False within the context of this conversation. While it is technically true that you can sustain a wide range of speeds, what matters in this discussion is the maximum sustained turn rate. WW2 fighters cannot maintain anything close to their corner speeds at PS = 0, so their max sustained speeds occur at the point where the plane stops accelerating when the plane is being held in the tightest turn possible.

It is completely meaningless in a thread about which plane turns better to list sustained speeds that are not the speed for max turn rate.

August 20, 2020

@[TLC]MasterPoonerAre you referring to the data I posted with this comment ?

Quote

But the other large test was done using arbitrarily turn speeds instead of letting speed drop to sustained turn speeds.

August 20, 2020

55 minutes ago, [TLC]MasterPooner said:

Nope. False within the context of this conversation. While it is technically true that you can sustain a wide range of speeds, what matters in this discussion is the maximum sustained turn rate.

It's not technically true. It's true.

55 minutes ago, [TLC]MasterPooner said:

It is completely meaningless in a thread about which plane turns better to list sustained speeds that are not the speed for max turn rate.

The claim made at the start of the thread is about the sustained turn rate difference at 200 kts. Nowhere does it mention maximum turn rate. Besides, it is often desirable to turn at lower rates to avoid ending up vulnerable in a very slow state.

Edited August 20, 2020 by Mitthrawnuruodo

August 20, 2020

4 minutes ago, Mitthrawnuruodo said:

The claim made at the start of the thread is about the sustained turn rate difference at 200 kts. Nowhere does it mention maximum turn rate.

No it isn't. This is a thread about which plane turns better. 200 knots was an arbitrary value and that fact that it was chosen at all shows the faulty thinking that is going on here. Why do you think Holtzauge (whose posts I agree with) is posting doghouse plots instead of arbitrary turn speeds?

August 20, 2020

7 hours ago, Aurora_Stealth said:

lol, no one here is suggesting that it out-turns Spitfires - that's been put to bed a long time ago.

^ I think a few people in here need to really understand that

August 20, 2020

Pooner you are obviously very desperate to shut down what people are saying, and if you were sincerely interested in being constructive you would have shared the relevant and most useful test settings and supporting data before I had conducted my tests. You had plenty of time to do that, and waited until precisely the time afterwards so that you could then dump and invalidate what other people are doing - the intent is clear.

The tests are not meant to represent the tightest possible turn or the quickest permissible sustained turning performance. It is a sample of data that was requested for given conditions for input into software calculations and for simulating in models... the data can then be input for further calculation and to extrapolate further in these models. I have followed the set criteria for maintaining a level turn without losing altitude, with a set weight, a set speed with reasonable tolerances.

The whole point is to keep accurately at the set speed e.g. 400 km/h while also maintaining accurately that specific altitude... if you attempt to get the highest sustained turn rate, you have to change the bank angle which will inadvertently change one of those parameters. That's why it's surprisingly time consuming to do this in the first place.

August 20, 2020

14 hours ago, Aurora_Stealth said:

Well I'd love to, but there aren't many videos available of Skip Holm talking about the '109, I think there is a website with some of his details about it and some footage of him flying it.

On that same basis we could effectively dismiss the entire USAAF pilot accounts of WW2, seeing as most of them involved wild over-claiming based on "hyped up pub talk" in their accounts. I think we both know that's going a bit far. Not sure which tests you are referring to?

I'm not suggesting you base anything off just one pilot account... its there for adding some relevant context to the discussion. If there is a consensus universally among experienced warbird pilots... and they all say they feel very confident about engaging heavier aircraft like the Mustang (similar argument would apply to the Tempest) with superior turning performance in the Bf 109 at low speeds - you do have to ask why they are saying that.

As a side note, was reading the last pages of 'The Big Show' by Pierre Clostermann last night. He was running one of the Tempest squadrons from December 1944 and he provides some insights into the aircraft, I came across this very relevant passage regarding the Bf 109 K / Tempest that I felt was worth sharing here. He clearly was well informed about the Bf 109 K as he specifically knew some batches were initially built with a wooden tail stabilizer, and he specifically mentions and reminds his pilots in combat about the maneuvering speed which he felt was disadvantageous to the Tempest.

As a disclaimer (do i really need to say this?): Please do not not take single accounts at absolute face value, these contain opinions and subjective content and are posted here for contextual reasons for the sake of this discussion.

Also let's remember that Skip Holm's opinion is mirrored by the likes of Mark Hanna & Dave Southwood, both of whom also flew/fly the P-51.

August 20, 2020

3 hours ago, Aurora_Stealth said:

Pooner you are obviously very desperate to shut down what people are saying,

What you are saying is nonsense. Your literally quoting anecdotes on the first page from people who do not fly these planes at maximum power in the first place. I could dump dozens and dozens of P-51 pilot accounts claiming the exact opposite.

3 hours ago, Aurora_Stealth said:

shared the relevant and most useful test settings and supporting data before I had conducted my tests.

This doesn't even make sense. I took it for granted that if you were going to complain about something you would know how to do a sustained turn rate test in the first place. You clearly dont, and that prompted me to post my own data......which I posted a year ago. So it is doubly ridiculous because this is hardly new information, and I even mentioned this earlier in the thread.

3 hours ago, Aurora_Stealth said:

the intent is clear.

Oh my! The person you disagree with in a conversation posted data to show your own data was rubbish! what a novel revelation in a debate? Egad! But by all means test away. My point was just to show that the impression being claimed that the 109 does not have a one second advantage in this game is simply false. It does. The 150 octane fuel P-51 is basically on a par, but not at an advantage. Its actually slightly worse.

3 hours ago, Aurora_Stealth said:

The tests are not meant to represent the tightest possible turn or the quickest permissible sustained turning performance.

Then they are pointless in a conversation about whether the 109 out turns the P-51 in this sim. They were relevant to testing the drag effects on acceleration. And your quoted turns were not the only ones I was responding to.

Edited August 20, 2020 by [TLC]MasterPooner

August 20, 2020

43 minutes ago, Panthera said:

Also let's remember that Skip Holm's opinion is mirrored by the likes of Mark Hanna & Dave Southwood, both of whom also flew/fly the P-51.

Yes quite - as with many of the other regular warbird pilots.

14 hours ago, HomicideHank said:

Very interesting interview. P-51 ace describes out-turning 109s in only a couple turns: http://www.youtube.com/watch?v=TmzzuMzOcKM&t=44m34s

Anyway, I think it would be close between a P-51 and an ME109. I think it'd be very close. But this is like, what 109? Some 109s don't turn very good at all. The big engine ones aren't good. Now, maybe like the 109E, is it the 109E? Maybe might be the best. And the P-51B is better than the D here. So maybe the 109E might outdo the D, but maybe not the B.

Cheers for sharing that link Hank - its very good. I have heard this particular account a couple of times before (think it was mentioned on the series Dogfights), but not in that detail - it's really nice to see an up-close interview with him. He's quite a like-able guy and clearly a tenacious pilot - I respect that.

Just for clarity, and for the sake of discussion here we're generally talking the late G and K models of Bf 109 versus the B, C and D models of Mustang.

The issue to me is, he seems to be one of the few exceptional pilots who had been able to pull off successful turning battles against the Bf 109 decisively in the Mustang. I suspect he's compensating much better through his experience and skills, whereas the '109 pilots are making a series of tactically strange maneuvers. For example holding a climb without taking any evasive action when in gun range and another inverting the aircraft while remaining straight and level as a target - these are not the maneuvers you would expect from experienced pilots.

He very clearly mentions at 44:05 the effect of altitude at 28,000 - 29,000 feet (8,5 km) and that up there the Mustang will be at its best due to the supercharger config which makes great sense - so it's plausible that at those very high altitudes where the engine settings are more favourable to the Mustang that things are different in terms of turning performance compared to lower/medium altitudes.

At 47:23 he describes the pilot who pulls a high energy turn, and he interestingly doesn't try to follow knowing he will lose a great deal of energy.

Appreciate this, thanks very much for sharing.

August 20, 2020

@Aurora_Stealth and @[TLC]MasterPooner: Thanks for doing the tests and as far as I can tell your results for the Me-109K4 don't really contradict each other or my simulations:

Beginning with the tests @Aurora_Stealth did at as I understand it 1 Km altitude summer conditions with 100% fuel 1.8 ata:

At 300 Km/h IAS I get 22.1 s turn time in the simulator while the measured result in-game is 21.7 s which is a good fit.

Also at 320 Km/h the results tab well: Simulator 21.0 s and in-game 21.8 s.

However, the simulations are at 15 C and the in-game results from summer conditions which I believe is 20 C which if anything, suggests that the in-game results are slightly optimistic.

However, this was also what I said earlier on: My impression is not that the best sustained turn times are off but that it may be so that the induced drag/propeller efficiency modeled at low speeds is a bit pessimistic which was why I suggested testing at speeds lower than 300 Km/h IAS as well.

The 19.5 s turn time result posted by @[TLC]MasterPooner for the the Me-109K4 with 100% fuel 1.8 ata were as I understand it for SL?

If so there is good agreement between simulations and in-game results here as well:

In the simulator I get 19.8 s while in-game it is 19.5 s. In this case results are directly comparable since they were done on the 15 C Autumn map.

August 20, 2020

It should also be noted that a lot of 109's Mustang pilot would encounter were equipped with gunpods to deal with the bombers, and a newly trained LW pilot in 109G6 with gunpods taking on a well trained Mustang pilot at high altitude was not really a recipe for success.

August 20, 2020

3 hours ago, Aurora_Stealth said:

Just for clarity, and for the sake of discussion here we're generally talking the late G and K models of Bf 109 versus the B, C and D models of Mustang.

The issue to me is, he seems to be one of the few exceptional pilots who had been able to pull off successful turning battles against the Bf 109 decisively in the Mustang. I suspect he's compensating much better through his experience and skills, whereas the '109 pilots are making a series of tactically strange maneuvers. For example holding a climb without taking any evasive action when in gun range and another inverting the aircraft while remaining straight and level as a target - these are not the maneuvers you would expect from experienced pilots.

Three (3) Me 109's destroyed. "This 109 was a little slow in entering his original turn and in the turning encounter that followed - lasting about 3 minutes - I got on his tail and observed many strikes on his wings and fuselage."

"We went into a Luftberry circle at about 10,000 ft, making approximately five 360° turns. I was turning slightly inside of him which he evidently saw because he reefed it in harder. He suddenly snapped over and went into a spin."

"After about 3 turns with our wing tips barely missing the trees, he pulled it in too tight and did a complete snap roll and ended up on his back, hitting the ground about the same time."

"I got in a Lufberry with an Me-109 at 10,000 ft. and we went around twice. I out-turned him and he straightened out, pulling across my nose."

"I made six 360° turns with the Me. 109s still following when a grey nosed P-51 attacked the rear ship, shooting down in flames.

It was easy to turn with them. In 180 degress of turn I caught the last Me 109. Opened up at about 300 yards; got good strikes; he burned and smoked."

“I continually out-turned him.”

"I broke and we went around in a Lufberry about 3 times."

"He tried to turn me in a turn to the left but I had no trouble staying inside of him without wing flaps."

"They both started turning to the left and we fell into a Luftberry that continued for about 10 to 15 minutes."

"Breaking into them we went around in a luftberry four of five times, when the lead 190 split S-ed and headed for the deck."

Some of these are 190s, feel free to read through them all. Many, are 109s. The ones I posted here are all 109s, and all of them report either close turning performance or it being easy to out turn them. Small wonder the 109 pilots all say the same thing, that there airplane was more agile.

Oh wait, thats precisely what you would expect if the planes were similar in terms of their turn performance.

August 20, 2020

59 minutes ago, [TLC]MasterPooner said:

What you are saying is nonsense. Your literally quoting anecdotes on the first page from people who do not fly these planes at maximum power in the first place. I could dump dozens and dozens of P-51 pilot accounts claiming the exact opposite.

This doesn't even make sense. I took it for granted that if you were going to complain about something you would know how to do a sustained turn rate test in the first place. You clearly dont, and that prompted me to post my own data......which I posted a year ago. So it is doubly ridiculous because this is hardly new information, and I even mentioned this earlier in the thread.

Oh my! The person you disagree with in a conversation posted data to show your own data was rubbish! what a novel revelation in a debate? Egad! But by all means test away. My point was just to show that the impression being claimed that the 109 does not have a one second advantage in this game is simply false. It does. The 150 octane fuel P-51 is basically on a par, but not at an advantage. Its actually slightly worse.

Then they are pointless in a conversation about whether the 109 out turns the P-51 in this sim. They were relevant to testing the drag effects on acceleration. And your quoted turns were not the only ones I was responding to.

Dude, warbirds are typically flown using max continuous engine settings to preserve engine life. Go and ask John Romain of the Aircraft Restoration Company (ARCo) who has been maintaining and flying these types of aircraft for over ten to twenty years. That means they use comparable engine settings during operation and display.

Yes we will test as seen fit to support the requests and investigations that are ongoing. Clearly they are relevant to us, its not all about you lol.

25 minutes ago, [TLC]MasterPooner said:

Some of these are 190s, feel free to read through them all. Many, are 109s. The ones I posted here are all 109s, and all of them report either close turning performance or it being easy to out turn them. Small wonder the 109 pilots all say the same thing, that there airplane was more agile.

Oh wait, thats precisely what you would expect if the planes were similar in terms of their turn performance.

First of all, the topic is discussing the 109 not the 190 so there's that of course.

I'm sure if you look hard enough you will find plenty of combat reports that contradict - but can you honestly say hand over heart that in 1944 / 45 that with the large disparity in average hours of training, fuel issues and material issues in the Luftwaffe (that was well documented by the USAAF) this gives a fair yardstick for comparison? is that not why it is strongly contradicted in the modern day?

How do you know which aircraft were fitted with underwing gondola's on these accounts? they often we're.. so you don't know what you're comparing - that's what makes it difficult to pin this down from these accounts. But I don't disagree, there is plenty of circumstantial evidence that can be found on the other side.

The quote I put up of the Tempest for example specifically states Clostermann was outmaneuvered by Bf 109 K's with gondolas attached from the firing seen under the wings and not just the nose. Gondolas's are not fitted to warbird aircraft for flight ops which helps make the comparison clearer.

Edited August 20, 2020 by Aurora_Stealth

August 20, 2020

9 hours ago, Aurora_Stealth said:

Dude, warbirds are typically flown using max continuous engine settings to preserve engine life. Go and ask John Romain of the Aircraft Restoration Company (ARCo) who has been maintaining and flying these types of aircraft for over ten to twenty years. That means they use comparable engine settings.

They are not the settings the planes flew at in combat. Especially not the settings used with water injection or high grades of fuel. Continuous power settings are not comparable, and these people are not putting these planes through rigorous turn tests. Its all anecdotal. Taking a bunch of airshow pilots opinions as law is just down right silly. Plus go check out Chris Faheys opinion on this on his facebook page for the P-51. He also flys these planes, and he has alot to say about people who suggest the P-51 is massively worse than a 109.

9 hours ago, Aurora_Stealth said:

Yes we will test as seen fit to support the requests and investigations that are ongoing. Clearly they are relevant to us, its not all about you lol.

Who the heck said you couldnt? You are under some kind of odd impression I tried to tell you not to test things.

9 hours ago, Aurora_Stealth said:

not the 190 so there's that of course.

Do you read? I pointed that out. All of the ones I posted except one, were vs 109s.

9 hours ago, Aurora_Stealth said:

'm sure if you look hard enough you will find plenty of combat reports that contradict - but can you honestly say hand over heart that in 1944 / 45 that with the large disparity in average hours of training, fuel issues and material issues in the Luftwaffe (that was well documented by the USAAF) this gives a fair yardstick for comparison? is that not why it is strongly contradicted in the modern day?

Yes this is the entire point... When two planes are very significantly different in turns you get almost no reports to the contrary. The fact that differences in skills, conditions, luck etc, appears to have made the difference suggests very strongly that the difference in performance was not huge.

Almost every sim made over the last twenty years had shown these planes to have comparable turn rates, with the 109 always the better of the two. Holtzauges simulation shows the same result. Real world anecdotes show wild disagreement between accounts, on both sides.

So in this game we have these two planes, and once again there performance is about 1 second apart. And low and behold....everyone has different impressions of which plane turns better in game. Small miracle.

Edited August 20, 2020 by LukeFF

August 20, 2020

@[TLC]MasterPooner, if you can't show respect to other people who have a different opinion to you then that's your problem. Thanks for sharing the data, anything that can assist is appreciated - but this could have been done at the start of the thread not waiting and then deliberately attacking once other people do.

We're trying to assess if there is an issue related here, and you are being rude and throwing up a tantrum with clear intent.

@Holtzauge, will follow-on with tests below 300 km/h later in the week and see what data I get. For the sake of maintaining consistency in the dataset, will keep with the load-out and other map settings for now. Cheers.

Edited August 20, 2020 by Aurora_Stealth

August 20, 2020

3 hours ago, Aurora_Stealth said:

Pooner, if you can't show respect to other people who have a different opinion to you then that's your problem.

We're trying to assess if there is an issue related here, and you are being rude and throwing up a tantrum in an attempt to de-rail it.

No, I gave evidence that there ISNT a problem here......precisely what your portend your are trying to discover........and you are being intellectually dishonest and trying to frame my responses as me being mean to you or telling you you cant test it. And your last post was a cop out.

If your going to engage in a debate or discussion, be prepared to have other people point out the errors you make.

August 20, 2020

2 hours ago, [TLC]MasterPooner said:

Taking a bunch of airshow pilots opinions as law is just down right silly. Plus go check out Chris Faheys opinion on this on his facebook page for the P-51. He also flys these planes, and he has alot to say about people who suggest the P-51 is massively worse than a 109.

Who the fuck said you couldnt? You are under some kind of odd impression I tried to tell you not to test things.

Do you read? I pointed that out. All of the ones I posted except one, were vs 109s.

And low and behold....everyone has different impressions of which plane turns better in game. Small miracle.

Note for reference: based on continued aggression, excessive rudeness and disrespect and the clear identification of your personality pattern. X Ignore User.

Edited August 20, 2020 by Aurora_Stealth

August 20, 2020

15 hours ago, Floppy_Sock said:

I've seen your posts a few times now looking back. I appreciate you sharing your methods a bit - no need to indulge more on those. I've written my fair share of CFD simulations - I'm well aware of the enormous effort it takes writing your own. Kudos. Wish my work was more applicable here

Thanks for the source - I went back to the report that was mentioned above by Panthera, I realize I remember the high alt data not the data from SL. See figure 6 in the naca TN 1044 (https://ntrs.nasa.gov/citations/19930084610) P51B was waxed, polished, power off - similar to the report you posted.

Do you happen to have any power on lift data for these birds?

I have plenty more questions but as to not derail the original discussion, this isn't the place to ask - maybe some other time.

Thanks

Thanks for reminding me about TN1044: Had it on my drive and looking at the figure you posted that ties in nicely with the NACA report 829 figure of Clmax=1.4 for low Mach in-service and 1.44 for pristine polished then.

In addition, I did a calculation to what is being used in-game and I came up with Clmax=1.34 for the Mustang and 1.39 for the K4 assuming that the lower quoted stall speed figure is for 10% fuel no ammo which I believe @unreasonable has concluded from his studies of the correlation between the stall speed numbers and weights in the in-game tech specs.

So it seems that my simulations and BOX power off Clmax assumptions are pretty much on the same page here and in addition, I believe those are also quite close to the numbers used in DCS as well so hopefully this can put a cap on the Clmax discussion at least.

When it comes to Clmax at power on conditions I have not dug up so much information about that since the way I set up the simulator I use Clmax power off as input. I did post results for the Spitfire in power on condition though earlier in this thread. I think I said Clmax=1.8 there based on looking at the graphs but it turns out this was also listed in the text and a more accurate number is 1.89.

Edited August 20, 2020 by Holtzauge

August 20, 2020

Yes - sticking all the data from the Tech Specs page into a spreadsheet, using the flight configuration minimum stall speed + minimum operating weight, and the maximum stall speed plus the maximum take off weight, many of the aircraft have the same calculated CLmax, to the second decimal. Most of those that differ only do it by ~0.01 to 0.03 Most of the 109s come out at 1.39-1.40 So I think that is the pairing of speed and weight appropriate. There are a few odd exceptions, the 109 E-7 and G-4, but I do not know why.

So I think that the minimum figure gives the best estimate of what the FM is using for the clean wing, perhaps there are other factors that come into play with planes with a high potential load. But I make no claims to know why or how that might be - I can only stick numbers into a spreadsheet!

The K-4 comes out as 1.39 for both weight/speed settings, the P-51 D at 1.34 for the minimum, 1.37 for the maximum (Cough... Tempest 1.52-1.53 cough... )

August 20, 2020

16 hours ago, Floppy_Sock said:

I've seen your posts a few times now looking back. I appreciate you sharing your methods a bit - no need to indulge more on those. I've written my fair share of CFD simulations - I'm well aware of the enormous effort it takes writing your own. Kudos. Wish my work was more applicable here

Thanks for the source - I went back to the report that was mentioned above by Panthera, I realize I remember the high alt data not the data from SL. See figure 6 in the naca TN 1044 (https://ntrs.nasa.gov/citations/19930084610) P51B was waxed, polished, power off - similar to the report you posted.

Do you happen to have any power on lift data for these birds?

I have plenty more questions but as to not derail the original discussion, this isn't the place to ask - maybe some other time.

Thanks

The only caveat is that we don't have low alt results for the conventional airfoils from the same source for direct comparison. However the difference is quite large at high altitudes, infact the recorded Clmax of the conventional airfoil F6F is actually higher pr. mach at high altitude than the Clmax pr. mach of the P-51B at low alt, and we need to be comparing at the same mach numbers.

As for the power on Clmax, there's little hard data on this for these birds, which is a shame as this is where the 109 benefits from its slats in terms of Clmax, power off there will be little benefit as the root section stalls much earlier.

August 20, 2020

I just realized that this whole discussion about Clmax and turn rates is actually a bit of a groundhog day since it was all covered exhaustively already back in 2016 here.

In addition, I just spoke to the Headmaster and everyone is now tasked with reading through all 11 pages, exam covering Clmax effects on turn rates will be tomorrow, no exceptions. If you fail you will NOT be allowed any sim time next week. Understood?

August 20, 2020

28 minutes ago, Holtzauge said:

I just realized that this whole discussion about Clmax and turn rates is actually a bit of a groundhog day since it was all covered exhaustively already back in 2016 here.

In addition, I just spoke to the Headmaster and everyone is now tasked with reading through all 11 pages, exam covering Clmax effects on turn rates will be tomorrow, no exceptions. If you fail you will NOT be allowed any sim time next week. Understood?

Will the exam be multiple choice? *crosses fingers*

August 20, 2020

First part essay 500 words. Second part multiple choices of the type "What is the maximum lift coefficient of the Me-109 K4?" (1=below 1.1, 2=About 1.4, 3=Well in excess of 5) which is why I suspect some will fail miserably.

August 20, 2020

So did a bit of testing in IL2, and here's what I got at 370 km/h (200 kts) at sea level compared with DCS:

IL2 @ 370 km/h sea level:

P-51D, 400 L, 67" Hg: 3.4 G's sustained

109K-4, 400 L, 1.8ata: 3.3 G's sustained

109G14, 400 L, 1.8ata: 3.3 G's sustained

DCS @ 370 km/h sea level:

P-51D, 400 L, 67" Hg: 3.0-3.1 G's sustained

109K-4, 400 L, 1.8ata: 3.6-3.7 G's sustained

Also carried out the test at 300 km/h in IL2:

IL2 @ 300 km/h sea level:

P-51D, 400 L, 67" Hg: 3.0 G's sustained

109K-4, 400 L, 1.8ata: 2.9 G's sustained

109G14, 400 L, 1.8ata: 2.9 G's sustained

Edited August 20, 2020 by Panthera

August 20, 2020

Is this of any use?

Edited August 20, 2020 by 71st_AH_Barnacles

109 sustained turn performance

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