Dora vs Mustang: Turning

[Pilum]

Both tests (Figures) apparently feature propeller removed with no flaps, wind speed 60 MPH.

 

Figure 16 is also accompanied by text below it where comments values from Figure 4: "The maximum lift coefficient of 1.44 for the faired and sealed condition and of 1.40 for the service wing are higher than those obtained for airplanes 5 and 6".

 

Perhaps there are some graph scale errors in the Figure 16 with the X & Y axis.

 

 

EDIT: Things like these make me wonder if Hummingbird actually studied the document or just searched it for the values he wanted to find...

 

It seems a bit difficult to determine an exact value for the P-51 because in addition to what you mention above, there is also figure 29 on page 26 in the same report and there is also mention of cover plates over the gun ports so to determine a figure from this is tricky. I’m leaning towards raising the Clmax to 1.4 in my C++ simulation though. My rationale for this is that the P-51 needs a good finish in order to attain top speeds and that since these are the ones we generally assume anyway, we might as well assume good conditions at stalling, ergo 1.4 seems like the value to use. I think this makes sense as well because a lot of the German data we see is also for sealed and polished conditions. Anyway, did not Erich Brunotte bribe his ground crew with Schnapps and cigarettes to polish his ride?

 

Things like these make me wonder if Hummingbird actually studied the document or just searched it for the values he wanted to find...

 

Yes Hummingbird: You do seem to have a penchant for pushing outliers in the data: high German and low Allied :music_whistling:

[Pilum]

I mean that even at low altitude 100 m/s (360 kph) that is typically the best sustained turn speed Mach number is about 0.3M. CL max difference between stall (0.12-0.15 M) speed and the best sustained turn speed can be up to 0.15-0.2 (15%).

If we take in consideration the corner speed and instanteneous turn the difference becomes greater and, moreover, different airfoils have very differnet cirves for it vs M and Re.

 

For example, low-drag airfoils are better for 0.5-0.7M in comparison with conventional 23 or 44 NACA series.

 

Yes, I agree with what you say: There is a Mach influence on Clmax and this will lower the Clmax you can use in the turn. I also compensate for this in my sim because otherwize the turn times will be too optimistic. As you say, the laminar airfoil did have good compressibility properties but that was also something the NACA 23 series had as well compared to other contemporary foils, albeit perhaps not as good as the laminar foils. The Spitfire did quite well also in compressibility but that was more due to the thinner wing than the wing profile.

 

Speaking of Mach, I did a quick dive test with the Dora the other day and I’m impressed that you have modeled the subsonic drag rise so well. I did not clock the details but IIRC then the terminal Mach was in the order of 0.75 to 0.8 and that this is so well modeled in DCS is a big step forward in sim modeling in general and since this is lacking in some other contemporary sims a big plus for DCS.

 

I do hope DCS does as good a job on the Me109K4 elevator stick forces because some earlier sims got this wrong and at high altitude the elevator control was basically lost at quite low dynamic pressures which IMO was not correct since the Mach was well below the critical for the elevator and it seemed that it was TAS not the dynamic pressure (IAS) that governed the elevator behaviour. What is your opinion Yo-Yo and what are the plans in DCS on this point?

[Hummingbird]

I did a calculation of the delta in Clmax as affected by a change in aspect ration 5.22 (Me109E) to 6.14 (Me109K4) and this only gave a 0.02 increase when I used the NACA 230012 profile Clmax 1.6 as base. So there is not much of a difference in theoretical Clmax between the Emil and the Kurfurst as you would like to believe.

 

Concerning the 1.65 to 1.7 figure you can’t reason as you do: Irrespective if we are talking about the Emil or Kurfurst, the inner part of the wing will stall at around 18 degrees. At this aoa the slats are fully out because they start to deploy at around Cl=0.8 and are fully out at 18 degrees aoa and Cl=1.4 to 1.45. Now if we continue to increase the aoa, the slatted part of the wing will happily go along and the lift will increase on this part of the wing. However, what happens on the rest of the wing is that the flow separates and lift is lost. So the overall effect is that the wings Clmax goes down between 20-30 degrees aoa, ergo you reach your wings peak lifting capacity of Clmax=1.4 to 1.45 at 20 degrees aoa and if you go to higher aoa to try to utilize what the slats can do on that part of the wing, you loose more than you gain on the other part of the wing. You really need to let this go now…..

 

Alos, I think that the reason the F4U turns better than the P-51 is simply because it has an 8% lower wing loading and 8% better P/W ratio so no mystery there.

 

Finally, I raise my hat since it is a rare day on the internet when someone concedes to being wrong about anything!

 

Pilum the inboard part of the 109's wing is a 2R1 airfoil of 14.2% thickness and its' CLmax & critical AoA will be higher than that of the thinner (11%) outboard part. Thus putting slats on the outboard part of the wing will increase the overall CLmax of the entire wing - in addition allowing the plane to be pulled into a harder turn before experiencing an accelerated stall because of boundary layer seperation at the outboard part of the wing.

 

Thus a CLmax in excess of 1.45 is to be expected for the entire 109F,G & K wing with slats.

 

NACA established a 1.53 CLmax for the 2R1 airfoi at 12% thicknessl:

Edited September 4, 2014 by Hummingbird

[Pilum]

Since the Clmax at zero degree flap discussion now seems to have converged I did some C++ simulations to gauge the relative turn performance for the Dora versus the P51D assuming a low speed Clmax of 1.35 and 1.4 respectively. I'm still assuming a low speed Clmax of 1.35 for the Dora because I don't think anything has come up yet that points to any better value.

 

Concerning the weights, I have assumed the same fuel load for both: 388 Kg since this was the maximum fuel load for the Dora in DCS. I think comparing same fuel percentage is wrong since the P51D has a greater internal fuel load capacity and should not be penalized for this. So the same fuel load seems more fair. In addition, I think it would make sense to compare with an even lower P51 fuel load since an even fairer comparison would be to specify the fuel needed say for 30 min endurance or something similar and then use that fuel load in the comparison.

 

I have also include two curves for the P51: One is assuming the high speed low drag bucket Cdo figure also for the turn which is IMHO wrong since the P51 laminar profile only gives the low drag bucket gains at low Cl values. Since we are here concerned with Cl numbers close to Clmax then the profile drag for the laminar foil goes up basically to the same values as for the conventional NACA-23XXX series foil.

 

So reading off 16.7 deg/s for the Dora in the diagram gives a turn time of 21.6 s and reading of 16.4 deg/s for the P51 gives 22 s which is then a little quicker than historical data but that is of course due to the lower weight assumed.

 

The resulting simulated turn times agree quite well with historical data I think since the figure compares the turn rates for lower but IMHO fairer weights than the usually found historical data which is for full internal fuel weight which is unfair for the P51 since it carries so much more fuel load. If I instead assume full fuel weight loadouts at 10100 lb for the P51 and 4270 Kg for the Dora in the simulation the result is turn times at 1 Km altitude of 22.6 s for the P51 and 22.1 s for the Dora which agrees quite well with historical data I think.

 

So that the P51 turns better than the Dora at low altitude in DCS is not really historically correct IMHO, however seeing that the Dora in DCS outperforms the P51 in all other departments right now this may not be a bad thing for balance. However, the best way forward is probably to correct the relative turn performance as per above and also add the 72" and/or 75" boost option for the P51 to get both historical accuracy and a balanced plane set, especially seeing that there is basically no difference in turn rate at high altitude which surprised me really. Before doing the simulation, I would have expected the P51 to be significantly better at 8 Km altitude which is however not borne out in the simulation.

 

BTW: Entering a Clmax of 1.58 for the Dora and 1.7 for the Me109K4 in the C++ simulation gives turn times of 20.8 s for the Dora and 18.3 s for the Me109K4 at full internal fuel load at 1 Km altitude which hardly seems historical but maybe Hummingbird/Kurfurst has another opinion? :smilewink:

[Nedum]

Hey Pilum and Hummingbird,

 

where is your point?

Does anything of your discussion helps this thread?

I don't think so.

Maybe is a privat room for you both the better way or you both publish your dicussion per E-Mail?!

Maybe this is not your personal thread?

[[DBS]TH0R]

So that the P51 turns better than the Dora at low altitude in DCS is not really historically correct IMHO, however seeing that the Dora in DCS outperforms the P51 in all other departments right now this may not be a bad thing for balance. However, the best way forward is probably to correct the relative turn performance as per above and also add the 72" and/or 75" boost option for the P51 to get both historical accuracy and a balanced plane set, especially seeing that there is basically no difference in turn rate at high altitude which surprised me really. Before doing the simulation, I would have expected the P51 to be significantly better at 8 Km altitude which is however not borne out in the simulation.

 

Anyone tested their turn rates at 8km in-game? I'm interested in hearing Yo-Yo's comments on your simulated results.

 

 

 

Hey Pilum and Hummingbird,

 

where is your point?

Does anything of your discussion helps this thread?

I don't think so.

Maybe is a privat room for you both the better way or you both publish your dicussion per E-Mail?!

Maybe this is not your personal thread?

 

Seriously? Have you read the thread title and who the OP is?

[Pilum]

Anyone tested their turn rates at 8km in-game? I'm interested in hearing Yo-Yo's comments on your simulated results.

 

Well, I have not had time to try myself but I was kind of surprised that the C++ simulation indicates basically no difference: I would have expected the Pony to be significantly better up high due to the lower wing loading.....

 

And seeing the turn rate is only 7.8 deg/s it takes a loooong time to turn: around 46 s....

Edited September 6, 2014 by Pilum

[WinterH]

Hey Pilum and Hummingbird,

 

where is your point?

Does anything of your discussion helps this thread?

...

 

I, for one, very much enjoy reading those informed insights and discussion, besides they look perfectly on topic to me.

 

Also, we see opposing points of view argue quite civilized for internet standarts on a forum, and even concede mistake when opposing view proves/presents itself valid. Almost scientific, this happening on an internet forum, especially a flight sim forum, alone is commendable thing all by itself ;)

[Robo.]

I, for one, very much enjoy reading those informed insights and discussion, besides they look perfectly on topic to me.

 

Also, we see opposing points of view argue quite civilized for internet standarts on a forum, and even concede mistake when opposing view proves/presents itself valid. Almost scientific, this happening on an internet forum, especially a flight sim forum, alone is commendable thing all by itself ;)

 

I totally agree, very good discussion, I really enjoy reading this thread. :thumbup:

[Hummingbird]

Since the Clmax at zero degree flap discussion now seems to have converged I did some C++ simulations to gauge the relative turn performance for the Dora versus the P51D assuming a low speed Clmax of 1.35 and 1.4 respectively. I'm still assuming a low speed Clmax of 1.35 for the Dora because I don't think anything has come up yet that points to any better value.

 

Concerning the weights, I have assumed the same fuel load for both: 388 Kg since this was the maximum fuel load for the Dora in DCS. I think comparing same fuel percentage is wrong since the P51D has a greater internal fuel load capacity and should not be penalized for this. So the same fuel load seems more fair. In addition, I think it would make sense to compare with an even lower P51 fuel load since an even fairer comparison would be to specify the fuel needed say for 30 min endurance or something similar and then use that fuel load in the comparison.

 

I have also include two curves for the P51: One is assuming the high speed low drag bucket Cdo figure also for the turn which is IMHO wrong since the P51 laminar profile only gives the low drag bucket gains at low Cl values. Since we are here concerned with Cl numbers close to Clmax then the profile drag for the laminar foil goes up basically to the same values as for the conventional NACA-23XXX series foil.

 

So reading off 16.7 deg/s for the Dora in the diagram gives a turn time of 21.6 s and reading of 16.4 deg/s for the P51 gives 22 s which is then a little quicker than historical data but that is of course due to the lower weight assumed.

 

The resulting simulated turn times agree quite well with historical data I think since the figure compares the turn rates for lower but IMHO fairer weights than the usually found historical data which is for full internal fuel weight which is unfair for the P51 since it carries so much more fuel load. If I instead assume full fuel weight loadouts at 10100 lb for the P51 and 4270 Kg for the Dora in the simulation the result is turn times at 1 Km altitude of 22.6 s for the P51 and 22.1 s for the Dora which agrees quite well with historical data I think.

 

So that the P51 turns better than the Dora at low altitude in DCS is not really historically correct IMHO, however seeing that the Dora in DCS outperforms the P51 in all other departments right now this may not be a bad thing for balance. However, the best way forward is probably to correct the relative turn performance as per above and also add the 72" and/or 75" boost option for the P51 to get both historical accuracy and a balanced plane set, especially seeing that there is basically no difference in turn rate at high altitude which surprised me really. Before doing the simulation, I would have expected the P51 to be significantly better at 8 Km altitude which is however not borne out in the simulation.

 

BTW: Entering a Clmax of 1.58 for the Dora and 1.7 for the Me109K4 in the C++ simulation gives turn times of 20.8 s for the Dora and 18.3 s for the Me109K4 at full internal fuel load at 1 Km altitude which hardly seems historical but maybe Hummingbird/Kurfurst has another opinion? :smilewink:

 

That's very interesting Pilum. I don't find a ~21 sec turn time for the Dora at full fuel and max power unrealistic.

 

I will however note that I do not insist that the Bf-109's CLmax is 1.7, only that I find it plausible.

 

Considering that the 14.2% 2R1 wing root section featured a CLmax of ~1.6, I would expect the overall wing to achieve a similar CLmax thanks to the slats helping prevent the outboard section of the wing from stalling before the root.

 

As for the NACA 23XXX vs NACA 66(1)-2XX airfoil, the CLmax achieved under std. roughness conditions are probably ones you should be looking at IMHO, and there the values are as follows:

NACA 23012 = 1.22

NACA 66(1)-212 = 1.01

 

Under smooth finish conditions the NACA 23012 achieves the exact same CLmax of 1.58 as in the Focke Wulf AG document (no flaps), whilst the NACA 66(1)-212 achieved a CLmax of 1.3.

 

But since a perfectly smooth finish was pretty unachieveable in the field, I'd say that we probably need to rely on the std. roughness figures for operational aircraft, and also here the NACA 23XXX airfoil had a definitive advantage in CLmax over the NACA 66(1)-2XX series.

 

Why this was not the case in report 829 I am not sure, perhaps a different airfoil design was used for the P-51 there (the type is described as experimental).

Edited September 7, 2014 by Hummingbird

[Pilum]

Based on some PM input on the turn rate figure I posted above I want to make some clarifications:

 

With the engine powers assumed, 67" for the P51 and B4 & MW50 boost for the Dora they are closely matched in turn rate as the chart also shows. However, if we instead assume 72 or 75" boost the P51 will outturn the Dora decisively.

 

In general terms, adding wing area or Clmax moves the left part of the "doghouse" chart to the left which raises the intersection to higher turn rates at lower speeds. Adding power raises the right hand part of the chart thus also moving the intersection point up increasing the turn rate which is then achieved at a higher speed.

 

So there are basically two ways to increase your turn rate: Add wing area and/or Clmax lowering the stall limit or add more power to pull yourself around in the turn. This also explains why the Dora does so well at 8 Km altitude I think: The best turn rate is no longer attained at Clmax but at a lower Cl and higher speed meaning that the power available to pull yourself around in the turn becomes more important than Clmax.

 

Another way to illustrate the point is to assume a Dora without the MW50 boost. So assuming the Jumo213A is instead producing roughly the same output as the P51, i.e. 1700 Hp at Steig & Kampffleistung, this would lower the right hand part of the Dora turn rate curve below that of the P51 and the Dora fastest turn time at 1 Km alt would increase to close to 25 s, i.e. a significantly lower turn rate than for the 67" P51.

 

This would then together with the fact that the majority of late war German pilots were not well trained go some way to explain all the pilot accounts of P51's outturning the Dora. So sure they did: Since Dora's with "Experten" at the stick and MW50 boost enabled were probably quite scarce the majority of the Dora's encountered were probably not that hard for a well trained late war Allied pilot to outturn. This is not even assuming that some of those P51 pilots probably had the possibility to go to 72 or 75" boost in a turnfight.....

 

Edit: Assuming Jumo213A at 1900 hp Notleistung without MW50 yields 23.5-24 s turn time at 1 Km alt so still longer than P51 at 67" boost.

Edited September 7, 2014 by Pilum

[Hummingbird]

I am still of the opinion that the FW190 held a clear advantage in the CLmax over the P-51 thanks to the NACA 23XXX airfoil. That the laminar flow NACA 66(1)-2XX airfoil with its sharp LE featured a higher CLmax than the NACA 23XXX series with its wider LE and higher camber makes very little sense, and indeed every windtunnel test besides that of report 829 (which notes an experimental airfoil) confirms this: the NACA 23012 for example in general holding a 0.2-0.3 advantage in CLmax.

 

Hence I see the FW190 outturning the P-51 esp. at lower speeds.

 

As LW ace Kurt Bühligen said:

"We would out-turn the P-51 and the other American fighters, with the Bf '109' or the FW '190'. The P-51 was faster than us but our munitions and cannon were better."

[[DBS]TH0R]

Interesting twist. Care to share from whom the input was Pilum? :)

 

 

Also, we see opposing points of view argue quite civilized for internet standarts on a forum, and even concede mistake when opposing view proves/presents itself valid. Almost scientific, this happening on an internet forum, especially a flight sim forum, alone is commendable thing all by itself ;)

 

Seconded. This thread is a welcome sight in contrast to the majority forum discussions.

[Yo-Yo]

Since the Clmax at zero degree flap discussion now seems to have converged I did some C++ simulations to gauge the relative turn performance for the Dora versus the P51D assuming a low speed Clmax of 1.35 and 1.4 respectively. I'm still assuming a low speed Clmax of 1.35 for the Dora because I don't think anything has come up yet that points to any better value.

 

Concerning the weights, I have assumed the same fuel load for both: 388 Kg since this was the maximum fuel load for the Dora in DCS. I think comparing same fuel percentage is wrong since the P51D has a greater internal fuel load capacity and should not be penalized for this. So the same fuel load seems more fair. In addition, I think it would make sense to compare with an even lower P51 fuel load since an even fairer comparison would be to specify the fuel needed say for 30 min endurance or something similar and then use that fuel load in the comparison.

 

I have also include two curves for the P51: One is assuming the high speed low drag bucket Cdo figure also for the turn which is IMHO wrong since the P51 laminar profile only gives the low drag bucket gains at low Cl values. Since we are here concerned with Cl numbers close to Clmax then the profile drag for the laminar foil goes up basically to the same values as for the conventional NACA-23XXX series foil.

 

So reading off 16.7 deg/s for the Dora in the diagram gives a turn time of 21.6 s and reading of 16.4 deg/s for the P51 gives 22 s which is then a little quicker than historical data but that is of course due to the lower weight assumed.

 

The resulting simulated turn times agree quite well with historical data I think since the figure compares the turn rates for lower but IMHO fairer weights than the usually found historical data which is for full internal fuel weight which is unfair for the P51 since it carries so much more fuel load. If I instead assume full fuel weight loadouts at 10100 lb for the P51 and 4270 Kg for the Dora in the simulation the result is turn times at 1 Km altitude of 22.6 s for the P51 and 22.1 s for the Dora which agrees quite well with historical data I think.

 

So that the P51 turns better than the Dora at low altitude in DCS is not really historically correct IMHO, however seeing that the Dora in DCS outperforms the P51 in all other departments right now this may not be a bad thing for balance. However, the best way forward is probably to correct the relative turn performance as per above and also add the 72" and/or 75" boost option for the P51 to get both historical accuracy and a balanced plane set, especially seeing that there is basically no difference in turn rate at high altitude which surprised me really. Before doing the simulation, I would have expected the P51 to be significantly better at 8 Km altitude which is however not borne out in the simulation.

 

BTW: Entering a Clmax of 1.58 for the Dora and 1.7 for the Me109K4 in the C++ simulation gives turn times of 20.8 s for the Dora and 18.3 s for the Me109K4 at full internal fuel load at 1 Km altitude which hardly seems historical but maybe Hummingbird/Kurfurst has another opinion? :smilewink:

 

I think you have some deniable initial values. First of all, CLmax for Dora is obviously too high because it gives the best turn rate TAS 340 kph that is too low in comparison with La-5 (350 IAS at 1 km). THe same airfoil but the lower weight/wing_area ratio. I think that the mistake is to assume CLmax at 0.3 M that is typical for the best turn (the point of intersection of two curves), so your CLmax is a little bit optimistic for P-51, too.

Anyway, even now your curves are suitable for comparing keeping in mind 20% difference in weight/area ratio.

 

So, your curves tell that Mustang do outturn Dora AT THE CERTAIN SPEED RANGE (270 -320 kph) both in turn rate and turn radius that is a keypoint for the sustained turn or stallfight (at max CL and drag/thrust balance) dogfight. High speed turn not at max CL is preferrable for Dora.

 

Anyway, the real high energy dogfight has elements of B'n'Z, instanteneous turns, high speed turns and max CL turns... so the overall picture seems to be very complicated. :)

[Pilum]

Interesting twist. Care to share from whom the input was Pilum? :)

 

Niet! :smilewink:: It was PM so it was in private but nothing strange really: Just an observation that my calculations did not tab with pilot reports and some questions about the results. Since it struck me that more people might have the same idea I thought I’d post my explanation for the discrepency (that calculated relative turn performance does not match P51 pilot accounts). Have no idea if I’m right but it seems plausible I think.....

Edited September 8, 2014 by Pilum

[Pilum]

I think you have some deniable initial values. First of all, CLmax for Dora is obviously too high because it gives the best turn rate TAS 340 kph that is too low in comparison with La-5 (350 IAS at 1 km). THe same airfoil but the lower weight/wing_area ratio. I think that the mistake is to assume CLmax at 0.3 M that is typical for the best turn (the point of intersection of two curves), so your CLmax is a little bit optimistic for P-51, too.

Anyway, even now your curves are suitable for comparing keeping in mind 20% difference in weight/area ratio.

 

So, your curves tell that Mustang do outturn Dora AT THE CERTAIN SPEED RANGE (270 -320 kph) both in turn rate and turn radius that is a keypoint for the sustained turn or stallfight (at max CL and drag/thrust balance) dogfight. High speed turn not at max CL is preferrable for Dora.

 

Anyway, the real high energy dogfight has elements of B'n'Z, instanteneous turns, high speed turns and max CL turns... so the overall picture seems to be very complicated. :)

 

The Clmax figure I have assumed for the Dora (1.35) may well be too high as you say but I don’t have any better data to go on. So if you have any that would be appreciated. Note that I have been fighting hard even for the 1.35 figure with Kurfurst/Hummingbird on this point who seem to think 1.58 is more appropriate!:helpsmilie:

 

Interesting with the La-5 turn time comparison. I don’t know too much about the La-5 or have it modeled in my simulation so I can’t really comment on the comparison other than that the La-5 had a better P/W ratio right? In this case the trend is for the best turnrate to occur at higher speeds so in that sense I’m not surprised but seeing that the La-5 has a lower wingloading I understand what you mean. So this would imply a lower Clmax than 1.35 then. What is used in DCS then? Do you have a figure for the La-5 Clmax?

 

On where the best turnrate occurs I’m not sure I agree that it’s not at the intersection of stall and power limits for the low altitude scenario. In fact also British RAE comes to this conclusion when they did the Spitfire and Me109 turn comparisons (RAE report RM 2361, Me109 handling and manoverability tests). However, when it comes to higher latitudes I agree: the best turn rate occurs at a lower Cl than the Clmax, which is also the case for the 8 km altitude turn scenario I posted.

 

Finally, I certainly agree that the Dora is not a turnfighter, however that was the topic of the OP so I wanted to give my input on this. I agree that the P51 has a smaller radius of turn but the turnrate is even more important so it looks like the Dora and Pony are quite evenly matched when B4&MW50 and 67” boost is assumed. I have not modeled 75” boost yet for the Pony but if that is introduced then based on the 67” figures then the Dora will certainly be outclassed in a sustained turnfight.

 

Edit:I know it's a bit off topic, but what about the Me109K4 elevator question I posted a bit earlier (#152) in this thread? Care to share some thoughts on that and how it should be modeled?:)

Edited September 8, 2014 by Pilum

[Hummingbird]

Again, how one can assume a higher CLmax for the P-51 in comparison to the Fw190 I cannot understand. Based on the knowledge we have on airfoils with sharper/narrower LE's, as well as the wind tunnel test figures, I see a clear advantage in CLmax to the wing with the NACA 23XXX airfoil - and that by a factor of atleast 0.2.

 

NACA 23012

 

 

 

NACA 66(1)-212

 

 

 

 

Wings with both airfoil types:

 

Wing with NACA 23015 (Root) 23009 (Tip) = 1.62

Wing with NACA 66(1)-216 (Root & tip) = 1.49 (1.42 straight wing)

[Yo-Yo]

2 Hummingbird.

The reason is that you are trying to see only HIGHEST values obtained from sterile tests. THe second reason is that the plane C coefficients are not exactly the coefficients of isolated wing sample because, at least, so called "wing area", plane C's refer to, generally includes fuselage area that has very different aerodynamics. Moreover, air flow through the fuselage/wing is not the same as through the isolated wing.

Test wing sample does not have gun ports, undercarriage openings, etc.

Additionally, Re and M combination, the test sample was measured at, are not the same as for the plane.

So, the Chalais Meudone wind tunnel test gave 1.15 Cl max for the clean FW-190 plane. Regarding relatively low Re it can be corrected to be aprox. 0.15-0.2 greater at higher Re but anyway - it's for extremely low M. At 0.3 M - for turns - it is lower.

Edited September 9, 2014 by Yo-Yo

[Yo-Yo]

I do hope DCS does as good a job on the Me109K4 elevator stick forces because some earlier sims got this wrong and at high altitude the elevator control was basically lost at quite low dynamic pressures which IMO was not correct since the Mach was well below the critical for the elevator and it seemed that it was TAS not the dynamic pressure (IAS) that governed the elevator behaviour. What is your opinion Yo-Yo and what are the plans in DCS on this point?

 

As we have some docs concerning 190 and 109 longitudinal controllability and stick forces at high IAS and M, I hope it will be ok.

Edited September 9, 2014 by Yo-Yo

[Kurfürst]

Note that I have been fighting hard even for the 1.35 figure with Kurfurst/Hummingbird on this point who seem to think 1.58 is more appropriate!:helpsmilie:

 

In fact all of your posts on this board are about fighting Hummingbird with hot puffs of smoke about the Clmax figures. If you're confused or paranoid about who is being who, let me help you out - you argue with Hummingbird, and that's and not me. So kindly stop intentionally mixing me up with someone else.

 

Edit:I know it's a bit off topic, but what about the Me109K4 elevator question I posted a bit earlier (#152) in this thread? Care to share some thoughts on that and how it should be modeled?:)

 

Be assured and rejoice, DCS already have the relevant documentation on this and other subjects.

[Hummingbird]

2 Hummingbird.

The reason is that you are trying to see only HIGHEST values obtained from sterile tests. THe second reason is that the plane C coefficients are not exactly the coefficients of isolated wing sample because, at least, so called "wing area", plane C's refer to, generally includes fuselage area that has very different aerodynamics. Moreover, air flow through the fuselage/wing is not the same as through the isolated wing.

Test wing sample does not have gun ports, undercarriage openings, etc.

Additionally, Re and M combination, the test sample was measured at, are not the same as for the plane.

So, the Chalais Meudone wind tunnel test gave 1.15 Cl max for the clean FW-190 plane. Regarding relatively low Re it can be corrected to be aprox. 0.15-0.2 greater at higher Re but anyway - it's for extremely low M. At 0.3 M - for turns - it is lower.

 

Right, as already stated the windtunnel tests of the day were quite unreliable in attaining accurate coefficients and different yet similar tests often yielded wildly different results.

 

That's why looking at stalling speeds, take off distances and landing speeds are helpful.

 

As an example the Bf-109G6 featured a clean (no flaps, gear up) stalling speed of ~140 km/h, the Spitfire IX one of 133 km/h, the FW190A8 one of 175 km/h and the P-51D one of 172 km/h (same as Dora-9).

 

What this proves is that the 190's wing had to have a higher CLmax in order for this to at all be possible, as its wing loading is higher.

 

That the FW190 featured a lower landing speed and shorter take off run than the P-51 can be explained by the more effective split flaps, which incidentally would also prove beneficial in a dogfight:

Edited September 9, 2014 by Hummingbird

[Pilum]

In fact all of your posts on this board are about fighting Hummingbird with hot puffs of smoke about the Clmax figures. If you're confused or paranoid about who is being who, let me help you out - you argue with Hummingbird, and that's and not me. So kindly stop intentionally mixing me up with someone else.

 

I see you retain your winning personality by resorting to personal attacks when a simple denial would do Kurfurst. Anyway, excuse me if I got you confused with Hummingbird but since you have a history of posting under nics suspecting that you are one and the same is not such a stretch so spare me the indignation please.

 

Be assured and rejoice, DCS already have the relevant documentation on this and other subjects.

 

I doubt you are in a position to make blanket statements on documentation in DCS's inventory Kurfurst. However, given your hubris you probably refer to the documentation you have contributed. In that case I’m sure DCS by now have figured out that this constitutes the absolute top performance outliers on the Me109 and the rock bottom results for the Spitfire and other allied aircraft.

[Pilum]

As we have some docs concerning 190 and 109 longitudinal controllability and stick forces at high IAS and M, I hope it will be ok.

 

OK, that sounds reassuring because I have had some bad experiences in a couple of “legacy” sims where even a shallow dive in a Me109 at around 8 Km to BnZ a B-17 resulted in “compressibility” problems and an inability to pull out and zoom after an attack even though both q and Mach was not that high. So good to hear that this is under wraps in DCS. :thumbup:

 

BTW: One good source on elevator stick forces and Mach limits is a report by Prestele: Me/VB/Re/10902E94 in translation “Relationship between Mach number and stick forces on Me109 and Fw 190” and I assume that you have that one already? If not let me know.

[The_Doktor]

Right, as already stated the windtunnel tests of the day were quite unreliable in attaining accurate coefficients and different yet similar tests often yielded wildly different results.

 

That's why looking at stalling speeds, take off distances and landing speeds are helpful.

 

As an example the Bf-109G6 featured a clean (no flaps, gear up) stalling speed of ~140 km/h, the Spitfire IX one of 133 km/h, the FW190A8 one of 175 km/h and the P-51D one of 172 km/h (same as Dora-9).

 

What this proves is that the 190's wing had to have a higher CLmax in order for this to at all be possible, as its wing loading is higher.

 

That the FW190 featured a lower landing speed and shorter take off run than the P-51 can be explained by the more effective split flaps, which incidentally would also prove beneficial in a dogfight:

Hi,

this diagram has something strange to it. CL max L means lift. But in german it is CA. A is for the german word Auftrieb. i doubt it is of german source....

[Yo-Yo]

OK, that sounds reassuring because I have had some bad experiences in a couple of “legacy” sims where even a shallow dive in a Me109 at around 8 Km to BnZ a B-17 resulted in “compressibility” problems and an inability to pull out and zoom after an attack even though both q and Mach was not that high. So good to hear that this is under wraps in DCS. :thumbup:

 

BTW: One good source on elevator stick forces and Mach limits is a report by Prestele: Me/VB/Re/10902E94 in translation “Relationship between Mach number and stick forces on Me109 and Fw 190” and I assume that you have that one already? If not let me know.

 

I would like to see the translation as I am not sure I have the English version.

I have a report about roll rate and ailerons effectiveness but the images have very small size and not convenient to read.