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Another look at turn times

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@Panthera: Have you looked through the whole thread Hiro linked to? There was actually a lot of interesting discussions earlier on in that thread about both the Clmax of many planes, the Fw-190, P-51 and Me-109 included and it was nice that the DCS developer Yo-Yo participated like he did.

 

Beginning with the stall speed Clmax, there is another report (NACA 829) that you should look at that has a full scale P-51 test which gives Clmax 1.4 for the Mustang. The thread is also interesting since there are some wild ideas put forward that the no flap Clmax for the Fw-190 should be as high as 1.58 and the Me-109 a whooping 1.7!

 

When it comes to the Clmax at higher than stall speed, I don’t have the figures in front of me but IIRC then at M=0.3 -0.4 the Dora and Pony are both modelled at around 1.2 to 1.25 in the C++ code. However, I don’t think the low speed Clmax is that big an issue since as you can see in the figures I posted, the “roof” of the doghouse charts are pretty much on the same level so if the stall boundary is moved to the right a bit on both planes due to a more conservative Clmax estimate that is not a big deal: They are still pretty much on par when it comes to stationary turn performance.

 

The above is however with the following caveats:

 

1) I have assumed the same fuel load for both the Pony and Dora: I don’t see why the Pony should be penalized for good endurance so I compare at a state with a similar endurance capability not with max internal fuel.

 

2) I have assumed the Dora with B4 fuel and MW-50 boost and the Pony at two WEP power states: one being 67” boost and the other 75” boost.

 

Under these conditions it turns out the difference was less than I anticipated and to me it looks like they are pretty evenly matched. The Clmax at moderate to higher Mach, say 0.4 to 0.6 (affected by buffeting etc.) is of course especially interesting for the instantaneous turn rate and there the report TN 1044 is really interesting. Another interesting report is NACA WR L6110 which has more input on the P-51 Clmax as affected by Mach.

 

@=LD=Hiromachi: About the other BoBp aircraft: I have a number of them modeled in C++ already since many of them are after all iconic and were a part of the earlier Il-2 plane set as well. Will be interesting to see how they are modeled in BoBp when the time comes.

 

 

Oh I agree that a Clmax of around 1.35-1.4 is entirely plausible for the P-51 at low altitude, NACA TN 1044 proves this as well. However the results in TN 1044 also show a marked difference in Clmax between the 23015-23009 wing/airfoil combination and the 66- one at 25,000 ft, from 1.35 of the F6F to 1.07 of the P-51 at 0.35 mach. That's a rather whopping difference of 26%. In other words the evidence available suggests that, in terms of clmax at the typical fighting speeds, the NACA 230xx series performs quite a bit better than the 66- series. 

 

However sadly no figures are presented for the 23015-09 airfoil type at low altitude to give us the definite answer, but to be honest I wouldn't expect something radically different down in the weeds.

 

Had a look at NACA 829, but it seems to only concern tests at 0 mach and thus aint really useful for anything but really slow level flight stalls :-/

Edited by Panthera

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Now this is but a guess but at SL to 1,000 ft and between  0.3 & 0.35 mach I'd expect the Fw190 to have a Clmax of around 1.45 to 1.4  as compared to the 1.25 and 1.2 of the Mustang. This is based purely on the data in NACA TN 1044, and namely the big difference seen between NACA 230xx &  66-  (as well as 00xx) at 25,000 ft.

 

The 66- series seems perform pretty much like a 00xx series in terms of lift but with the added benefit of reduced drag in level flight. 

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About the Clmax of the Fw-190 Panthera, before you started posting here there was a looooooooong animated discussion in this forum about this since the low speed Clmax was lowered from an AFAIK unknown value to 1.15 a few releases back. This, to put it mildly, was frowned upon any many of us in the forum worked hard on producing input to the developers and now the Fw-190 has about the same low speed Clmax as the other planes, i.e. in the range of 1.3 to 1.4. IMHO that is a good estimate given that the Spitfire has about 1.36 and the Me-109 (which benefits from no washout) has 1.4. If you want to convince the developers that they should go to 1.45 for the Fw-190 I think you will face an uphill struggle and frankly on the evidence I have seen so far I’m sticking to 1.35 in my C++ simulations.

 

How much these low speed Clmax figures should be lowered at M=0.3 to 0.4 is I think a very difficult task to figure out and in my C++ simulations I have assumed about the same lowering as a function of Mach for all of them which I think is fair unless there is specific data on this which there usually is not and therefore the low speed Clmax is I think a good starting point with a reduction applied to that value. In addition, in general I think it is very difficult to predict the Clmax by comparing different aircraft and assuming they have the same Clmax capabilities at M=0.3 to 0.4 solely on the wing profile since there are so many other factors in play: The wing planform, the wing washout, imperfections due to structure, surface finish and gun ports, gaps with leakage, aeroelastic effects etc. For example, the Fw-190 had a problem with wing twist at higher dynamic pressures in that when pulling g’s the outer portions of the wing twisted reducing the wash out which lead to that the outer portions stalled earlier than they should leading to vicious accelerated stalls.

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I see your point in relation to the other conventional type airfoils Holtzauge, I wouldn't expect the 190's Clmax to be noticably higher than these. However, with the exception of the camberless 00xx series, I would expect some noticable difference between these and the low drag 66- series on the mustang, the evidence in TN 1044 is just too overwhelming not too IMHO.

 

Would also help explain a host of real life tests, like how a Fw190 jabo was able to match a P-51B in turns during AFDU trials which undoubtedly took place at rather high altitude. Or the rather impressive 21 sec turn time for the A8 at TsAGi.

Edited by Panthera

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Well I'm assuming you are looking at figure 4 in TN 1044? What about figure 8 for the P-51 in the same report? There you have Clmax 1.4 at low Mach and then about 1.25 at M=0.3 and 1.2 at M=0.4 except for extremely high altitudes. This is pretty much in line with what I use in the C++ modeling.

 

Also I have a momentaneous turn diagram for the Me-109K4 at 6 Km altitude (Me header missing but marked 5026/33) with an initial  M=0.5+ in which Messerschmitt assume Camax=1.13 which given that the Me-109 has a Clmax at low Mach of around 1.4 is quite in line with the Mustangs 1.05 at M=0.5 in figure 8. I think this is interesting since the Me-109 wing profile 2R1 is very similar to the NACA 230xx series.

 

Edit: 21 s for the A8!!!! Really? Sounds like maskirovka to me....How on earth do you get a Fw-190A8 to do a full 360 in 21 s? :o:

Edited by Holtzauge

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Just about half way through it now and trying to follow the arguments - thinking that the fellow called Pilum was making some sharp points. ;)

 

Why thank you unreasonable! Well Pilum and I tend to agree on most things the reason for which becomes clear if you look at Pilum's sig in DCS. ;)

 

On a more serious note; The reason I joined there as Pilum, i.e. the Roman javelin, was that at the time I was flying the DCS F-15 and Su-27 and deeply interested in missile FM as my post history there will reveal. It was only later on I bought the P-51 module and started fiddling around with their WW2 modules.

Edited by Holtzauge
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Well I'm assuming you are looking at figure 4 in TN 1044? What about figure 8 for the P-51 in the same report? There you have Clmax 1.4 at low Mach and then about 1.25 at M=0.3 and 1.2 at M=0.4 except for extremely high altitudes. This is pretty much in line with what I use in the C++ modeling.

 

Also I have a momentaneous turn diagram for the Me-109K4 at 6 Km altitude (Me header missing but marked 5026/33) with an initial  M=0.5+ in which Messerschmitt assume Camax=1.13 which given that the Me-109 has a Clmax at low Mach of around 1.4 is quite in line with the Mustangs 1.05 at M=0.5 in figure 8. I think this is interesting since the Me-109 wing profile 2R1 is very similar to the NACA 230xx series.

 

Edit: 21 s for the A8!!!! Really? Sounds like maskirovka to me....How on earth do you get a Fw-190A8 to do a full 360 in 21 s? :o:

 

 

Oh I am looking at them all, both the low & high alt graphs, and in them the NACA 66- series appears to be quite similar to the camberless 00xx series, but at the same time noticably behind the 230xx series in their only direct comparison at 25,000 ft. It is this rather stark difference at 25,000 ft that I really can't understand if completely disappears at low alt, IMO it should be somewhat similar down there.

 

The 2R1 airfoil was basically a Clark Y series IIRC?

 

As for the TsaGi A8 time, I believe they got the A5 to do a 360 in 22 sec at 1.3ata (hence the low SL speed). Thus if the A8 was running at 1.42ata then 21 sec seems to line up pretty well with that. (PS: no clue if below chart is all the way trustworthy, some numbers would indicate not so much, but I just remember stumbling upon it the 21 sec for the A8)

1h1xOi7.jpg

Edited by Panthera

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Oh I am looking at them all, both the low & high alt graphs, and in them the NACA 66- series appears to be quite similar to the camberless 00xx series, but at the same time noticably behind the 230xx series in their only direct comparison at 25,000 ft. It is this rather stark difference at 25,000 ft that I really can't understand if completely disappears at low alt, IMO it should be somewhat similar down there.

 

The 2R1 airfoil was basically a Clark Y series IIRC?

 

As for the TsaGi A8 time, I believe they got the A5 to do a 360 in 22 sec at 1.3ata (hence the low SL speed). Thus if the A8 was running at 1.42ata then 21 sec seems to line up pretty well with that. (PS: no clue if below chart is all the way trustworthy, some numbers would indicate not so much, but I just remember stumbling upon it the 21 sec for the A8)

1h1xOi7.jpg

 

AFAIK the Me-109's 2R1 profile is quite similar to the 230xx-series not the Clark Y. Apparently both had the max of the camber line far forward which gave them both a high Clmax and low pitching moment characteristics. They also both turned out to have quite good compressibility characteristics which was purely fortuitous since at the time of their conception this was not a design goal but a byproduct of the other design requirements as I have understood it.

 

When it comes to the Fw-190 A8 doing 21-22 s turns according to Russian sources the table above explains it: They have assumed a weight of 3986 Kg which is way lower than the German (and my C++) A8 estimates I have seen which are in the 4300 to 4400 Kg bracket. At such a low weight as 3986 Kg I get a bit over 22 s as well at 1 Km altitude but at 4400 Kg it is in the 25 to 26 s bracket which was why my jaw dropped when I saw the 21 s figure. ;)

Edited by Holtzauge

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AFAIK the Me-109's 2R1 profile is quite similar to the 230xx-series not the Clark Y. Apparently both had the max of the camber line far forward which gave them both a high Clmax and low pitching moment characteristics. They also both turned out to have quite good compressibility characteristics which was purely fortuitous since at the time of their conception this was not a design goal but a byproduct of the other design requirements as I have understood it.

 

When it comes to the Fw-190 A8 doing 21-22 s turns according to Russian sources the table above explains it: They have assumed a weight of 3986 Kg which is way lower than the German (and my C++) A8 estimates I have seen which are in the 4300 to 4400 Kg bracket. At such a low weight as 3986 Kg I get a bit over 22 s as well at 1 Km altitude but at 4400 Kg it is in the 25 to 26 s bracket which was why my jaw dropped when I saw the 21 s figure. ;)

 

 

Yeah, not sure how they arrived at 3986 kg, any idea ? That aside if they could achieve 22 sec with a 4100 kg aircraft at 1.3ata (A5), then wouldn't you say 21 sec at 1.42ata seems reasonable?

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Yeah, not sure how they arrived at 3986 kg, any idea ? That aside if they could achieve 22 sec with a 4100 kg aircraft at 1.3ata (A5), then wouldn't you say 21 sec at 1.42ata seems reasonable?

Removing the other 20mm cannons (as is indicated in the table) can get you pretty close to it. ;)

 

In any case, the Russian figures appear to me as both reasonable and consistent within the samples, considerint the air plane conditions of course.

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Yeah, not sure how they arrived at 3986 kg, any idea ? That aside if they could achieve 22 sec with a 4100 kg aircraft at 1.3ata (A5), then wouldn't you say 21 sec at 1.42ata seems reasonable?

 

Well I would say 21 s is a very optimistic estimate: I was using 1.42 ata as well and I get about 22.5 s at 1 Km altitude with 3986 Kg. Removing MG151 with ammunition reduces the weight by 176.5 Kg according to the Fw 190 A-8 handbook D.(Luft) T.2190 A-8 which then becomes 4400-176.5=4223.5 Kg so in order to get down to 3986 Kg you would need to something else as well. For example, don’t fill up the auxillary fuel tank (90 Kg) and then don’t top of the main fuels tanks (total 410 Kg) and then you could get to 3986 Kg.

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Well I would say 21 s is a very optimistic estimate: I was using 1.42 ata as well and I get about 22.5 s at 1 Km altitude with 3986 Kg. Removing MG151 with ammunition reduces the weight by 176.5 Kg according to the Fw 190 A-8 handbook D.(Luft) T.2190 A-8 which then becomes 4400-176.5=4223.5 Kg so in order to get down to 3986 Kg you would need to something else as well. For example, don’t fill up the auxillary fuel tank (90 Kg) and then don’t top of the main fuels tanks (total 410 Kg) and then you could get to 3986 Kg.

Ah ok, well if you're arriving at 22.5 sec for 3986 kg then this is where I think you're using too low a clmax, considering that the A5 achieved this (22-23 sec) at 1.3ata and 4070 kg.

 

I believe this is where TN 1044 becomes useful. Have you tried what Clmax your simulation would demand for a 22-23 sec to turn 360 at 1.3ata & 4070 kg? Would be interesting to compare this with TN 1044 data :)

Edited by Panthera

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Ah ok, well if you're arriving at 22.5 sec for 3986 kg then this is where I think you're using too low a clmax, considering that the A5 achieved this (22-23 sec) at 1.3ata and 4070 kg.

 

I believe this is where TN 1044 becomes useful. Have you tried what Clmax your simulation would demand for a 22-23 sec to turn 360 at 1.3ata? Would interesting to compare this with TN 1044 data :)

 

Yup, here we seem to have different opinions: I'm not as optimistic as you when it comes to the Fw-190 Clmax. ;)

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Yup, here we seem to have different opinions: I'm not as optimistic as you when it comes to the Fw-190 Clmax. ;)

 

Indeed, but again it would be interesting to see what it took to get the 190 to do a 360 in 22-23 sec at 4070 kg & 1.3ata in your program :)

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Well, right now I'm not planning to change the Fw-190 modeling but if some compelling new info pops up I will. What I am more interested in is if there is any data on the Me-262's turn performance, Clmax and polar. The thing is that the symmetrical profile it uses is unaided terrible dragwize outside a very small aoa range but the question is with the slats it used, what did that do in terms of the Clmax and what did the polar look like with slats deployed? Now that would be interesting info since I suspect that it may be a better turner than it's reputation, especially at higher speeds....

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Well, right now I'm not planning to change the Fw-190 modeling but if some compelling new info pops up I will.

 

 

I understand and I like that you're careful not to accept new data too quickly, hence I am not telling you to change your modelling, it would just be interesting to see what your simulation would need in terms of Clmax to match the Russian test figures for the 190. I have a feeling it might end up beautifully matching TN 1044 data considering how accurate your simulation seems to predict performance (it's honestly the best I've seen) :)

 

 

What I am more interested in is if there is any data on the Me-262's turn performance, Clmax and polar. The thing is that the symmetrical profile it uses is unaided terrible dragwize outside a very small aoa range but the question is with the slats it used, what did that do in terms of the Clmax and what did the polar look like with slats deployed? Now that would be interesting info since I suspect that it may be a better turner than it's reputation, especially at higher speeds....

 

 

I fully agree, would be great with data specific to the Me262's NACA 0012 profile with slats, sadly I don't have any :(   The slats should improve the Clmax by quite a significant degree though according to all the charts on their effects I've seen.

 

YxpuVBj.jpg

OL8zTPG.gif

QHdS8Uf.gif

Edited by Panthera

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Yes, a full span slat will undoubtedly significantly increase the Clmax but as you already pointed out, while the low speed Clmax e.g. like at stall will be very positively affected but what about Mach effects? The Me-262 will have its speed for best turn rate at a much higher speed that a prop job since a no-bypass jet is basically a constant thrust producer while a propeller plane is a constant power producer so the speed for best turn rate will be at a higher Mach. In addition, in order to get to the Clmax the aoa will have to go much higher than on a prop plane where you will have the Clmax at typically 18-20 deg aoa. With a symmetrical profile and full span slats like on the Me-262 that will be increased to a higher aoa (22-25?) and that will significantly increase the drag. But even if the Clmax is there potentially maybe (and most likely probably) it will be buffeting limited at higher speeds so there is that as well. I’d really like to get some estimates on this so I'm planning to go looking but if you or someone else can dig up any more data on this that would be great. The figures you posted are a start but it would be good to get some more detailed data on full span slats at higher than stall speeds for finite wings. Maybe there is some NACA data over at the NTRS for the early post WW2 jets that could be useful…..

Edited by Holtzauge

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Yes, a full span slat will undoubtedly significantly increase the Clmax but as you already pointed out, while the low speed Clmax e.g. like at stall will be very positively affected but what about Mach effects? The Me-262 will have its speed for best turn rate at a much higher speed that a prop job since a no-bypass jet is basically a constant thrust producer while a propeller plane is a constant power producer so the speed for best turn rate will be at a higher Mach. In addition, in order to get to the Clmax the aoa will have to go much higher than on a prop plane where you will have the Clmax at typically 18-20 deg aoa. With a symmetrical profile and full span slats like on the Me-262 that will be increased to a higher aoa (22-25?) and that will significantly increase the drag. But even if the Clmax is there potentially maybe (and most likely probably) it will be buffeting limited at higher speeds so there is that as well. I’d really like to get some estimates on this so I'm planning to go looking but if you or someone else can dig up any more data on this that would be great. The figures you posted are a start but it would be good to get some more detailed data on full span slats at higher than stall speeds for finite wings. Maybe there is some NACA data over at the NTRS for the early post WW2 jets that could be useful…..

 

Yeah the F86 for example used similar full span slats AFAIK, they seem to have worked very well, also being reintroduced after the initial success with the 6-3 wing. I'll have a look around to see what I can find :)

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Found this aerodynamic summary for the F-86E: http://www.dtic.mil/dtic/tr/fulltext/u2/069271.pdf

 

EDIT: Seems to mostly concern itself with the effects of the new all moving tail, albeit there is one graph that lists the Cl increase from 1.0 with slats closed to 1.2 with slats open. This is for the very thin and highly sloped laminar flow wing of the F-86 ofcourse, so not sure how applicable it is.

Edited by Panthera
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So, what exactly is the point of this whole discussion, and how does it benefit BoS?

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So, what exactly is the point of this whole discussion, and how does it benefit BoS?

 

You do know that we're getting BoP soon right?  ;)

 

We've already discussed the aircraft present in BoS, and it seems the devs are aware of the issues there. albeit their reasoning for the issues being due to inaccurate prop efficiency numbers is improbable if they've got the other aerodynamic figures right.

Edited by Panthera

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Here's another one for the F-86F-40: http://www.dtic.mil/dtic/tr/fulltext/u2/096084.pdf

 

 

Panthera, that was a very good find, thanks for digging it up! :good:

 

Chapter 6 is an interesting read: To me it seems that while there is an onset of buffet prior to stall as excepted, I can’t find a reference there that indicates that this was in any way limiting how much Cl you could extract and that it was the Clmax that limited the load factor which I did not expect: I would have thought severe buffeting limited the attainable Cl but that does not seem to be the case for the Sabre’s tested anyway.

 

What really stands out I think is how high the Clmax is at higher Mach numbers: Figures 12, 13 and 14 indicate that not only is the Clmax reasonably high for such a thin wing but it does not reduce as much as the thicker and more cambered propeller plane profiles do and you are left with an amazing 0.8 in Clmax at M=0.9 which is really impressive!

 

Question is how much of this data can be assumed to be valid for the Me-262 though but since they both have slats and relatively thin symmetrical NACA profiles : root/tip 9/8.5% for the F-86 and 11/9% for the Me-262 they should at least be usable as a base. Of course the sweep, aspect ratio and planform probably plays in as well but this is the best data I have seen so far and I’m definitely going to update my Me-262 C++ model based on this. In the current model I’ve assumed a Clmax limit of 0.8 already at M=0.55 so this is going to move that to a higher speed for sure. OTOH, the Mach characteristics for a profile are usually more connected to the perpendicular Mach component so maybe the figures in the report should be used based on the relative sweep angle and relative profile thickness as well. Any thoughts on this?

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Found this aerodynamic summary for the F-86E: http://www.dtic.mil/dtic/tr/fulltext/u2/069271.pdf

 

EDIT: Seems to mostly concern itself with the effects of the new all moving tail, albeit there is one graph that lists the Cl increase from 1.0 with slats closed to 1.2 with slats open. This is for the very thin and highly sloped laminar flow wing of the F-86 ofcourse, so not sure how applicable it is.

 

Yes, this is a nice report as well, especially page 32 in the report (41 in the pdf) that shows the slats in and slats out difference in Clmax is interesting. For stationary turn performance the gradual curve would be the one to look at of course but it is still impressive with a Clmax=1 as high as M=0.625.

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Panthera, that was a very good find, thanks for digging it up! :good:

 

Chapter 6 is an interesting read: To me it seems that while there is an onset of buffet prior to stall as excepted, I can’t find a reference there that indicates that this was in any way limiting how much Cl you could extract and that it was the Clmax that limited the load factor which I did not expect: I would have thought severe buffeting limited the attainable Cl but that does not seem to be the case for the Sabre’s tested anyway.

 

What really stands out I think is how high the Clmax is at higher Mach numbers: Figures 12, 13 and 14 indicate that not only is the Clmax reasonably high for such a thin wing but it does not reduce as much as the thicker and more cambered propeller plane profiles do and you are left with an amazing 0.8 in Clmax at M=0.9 which is really impressive!

 

Question is how much of this data can be assumed to be valid for the Me-262 though but since they both have slats and relatively thin symmetrical NACA profiles : root/tip 9/8.5% for the F-86 and 11/9% for the Me-262 they should at least be usable as a base. Of course the sweep, aspect ratio and planform probably plays in as well but this is the best data I have seen so far and I’m definitely going to update my Me-262 C++ model based on this. In the current model I’ve assumed a Clmax limit of 0.8 already at M=0.55 so this is going to move that to a higher speed for sure. OTOH, the Mach characteristics for a profile are usually more connected to the perpendicular Mach component so maybe the figures in the report should be used based on the relative sweep angle and relative profile thickness as well. Any thoughts on this?

 

Yes the slats do seem to be very beneficial at high speeds, I definitely understand why they kept putting them on fighter jets for a long time until the advent of the automatically controlled leading edge flaps.

 

As for your question: The higher aspect ratio, lower sweep angle & slightly higher thickness ratio of the Me262's wing will probably increase the Clmax over that of the F-86, that's usually the case at least, but by how much? We need some similar graphs for slat equipped conventional airfoils to be sure, I'll see if I can't locate some.

Edited by Panthera

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Yes the slats do seem to be very beneficial at high speeds, I definitely understand why they kept putting them on fighter jets for a long time until the advent of the automatically controlled leading edge flaps.

 

As for your question: The higher aspect ratio, lower sweep angle & slightly higher thickness ratio of the Me262's wing will probably increase the Clmax over that of the F-86, that's usually the case at least, but by how much? We need some similar graphs for slat equipped conventional airfoils to be sure, I'll see if I can't locate some.

 

Sure, the low speed Clmax at stall will maybe be higher for The Me-262 than the F-86 due to thicker wing and less sweep but sweep also moves the subsonic drag rise to a higher Mach as became known a bit prior to the Me-262’s conception (although it was a c.g. correction, not Mach that triggered the Me-262’s sweep) and based on the Sabre data you linked it looks like the reduction of the attainable Clmax is also shifted to a higher Mach due to the sweep meaning the high Clmax figures the Sabre had at higher Mach are probably not attainable for the Me-262 with its much more modest sweep.

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Sure, the low speed Clmax at stall will maybe be higher for The Me-262 than the F-86 due to thicker wing and less sweep but sweep also moves the subsonic drag rise to a higher Mach as became known a bit prior to the Me-262’s conception (although it was a c.g. correction, not Mach that triggered the Me-262’s sweep) and based on the Sabre data you linked it looks like the reduction of the attainable Clmax is also shifted to a higher Mach due to the sweep meaning the high Clmax figures the Sabre had at higher Mach are probably not attainable for the Me-262 with its much more modest sweep.

 

Apologies Holtzauge, I completely misread your post yesterday and as a result didn't read your actual question, must have been the lack sleep o.O  I'm not familiar with sweep having the effect of flattening out Clmax at high mach, but you might be on to something, and if so then just like you said the mild sweep of the Me262's wing should mean that it's lift curve doesn't flatten out nearly as much - providing the slats didn't induce that effect ofcourse, but based on the chart below I doubt that as the "slats open" curve follows the "retracted" curve nicely up until the point where sufficient AoA can't be pulled anymore. 

 

k1M9q36.png

 

Also the above chart is probably for relatively low altitude, the lower Re at high altitude decreasing the Clmax to the 1.1 as seen below:

 

ePRm7qR.png

Edited by Panthera

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F-86, lol.

 

Anyone have info on actual LaGG-3 roll rate and elevator effectiveness?

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I really wish you would've followd the conversation instead of just assuming,

 

We're looking into the F-86 in an effort to maybe learn something about the Me262 as they both featured swept wings and shared a similar slat system. 

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I really wish you would've followd the conversation instead of just assuming,

 

We're looking into the F-86 in an effort to maybe learn something about the Me262 as they both featured swept wings and shared a similar slat system.

...and thus you and Holtzauge are just having a discussion that doesn't really have a bearing on any particular plane currently modeled in BoS. This sort of discussion really doesn't fit here and belongs somewhere else, like in Historical Data. C'mon, what does F-86 test data have to do with anything? It's a valid question posed by Cujo.

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...and thus you and Holtzauge are just having a discussion that doesn't really have a bearing on any particular plane currently modeled in BoS. This sort of discussion really doesn't fit here and belongs somewhere else, like in Historical Data. C'mon, what does F-86 test data have to do with anything? It's a valid question posed by Cujo.

 

As far as I can tell this forum isn't meant specifically for just BoS, but instead the entire revamp of the IL2 series. In addition I'm not really sure why Holtzauge & I's efforts in trying to figure out the proper way to predict Me262 characteristics bothers you so much. 

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F-86, lol.

 

Anyone have info on actual LaGG-3 roll rate and elevator effectiveness?

 

Yeah, so we should talk about the LaGG-3 roll and elevator efficiency in this thread instead? Iol.

 

...and thus you and Holtzauge are just having a discussion that doesn't really have a bearing on any particular plane currently modeled in BoS. This sort of discussion really doesn't fit here and belongs somewhere else, like in Historical Data. C'mon, what does F-86 test data have to do with anything? It's a valid question posed by Cujo.

 

Some facts for you : The Me-262 is in the pipeline and this is the FM section so this is the place for this type of discussion since the idea is to figure out how the Me-262 Clmax should be modeled. Why you feel the need to police the forum is beyond me. Why don't you leave that up to the moderators?

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Apologies Holtzauge, I completely misread your post yesterday and as a result didn't read your actual question, must have been the lack sleep o.O  I'm not familiar with sweep having the effect of flattening out Clmax at high mach, but you might be on to something, and if so then just like you said the mild sweep of the Me262's wing should mean that it's lift curve doesn't flatten out nearly as much - providing the slats didn't induce that effect ofcourse, but based on the chart below I doubt that as the "slats open" curve follows the "retracted" curve nicely up until the point where sufficient AoA can't be pulled anymore.

 

No problem, maybe I was not totally clear about what I meant earlier on but what you wrote above was it. I think this a very interesting issue since earlier flight sims like legacy IL-2 had the Me-262  turning like a dog and I don't think that is the case at all. As long as you keep your speed up it should probably turn quite well and I'm planning on updating the C++ Me-262 model based on this data so it will be interesting to see if this true or not.

 

 

 

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No problem, maybe I was not totally clear about what I meant earlier on but what you wrote above was it. I think this a very interesting issue since earlier flight sims like legacy IL-2 had the Me-262  turning like a dog and I don't think that is the case at all. As long as you keep your speed up it should probably turn quite well and I'm planning on updating the C++ Me-262 model based on this data so it will be interesting to see if this true or not.

 

Yes I also believe the Me262 turned very well at speed, which also seems to be mirrored in the opinions of the pilots. The key part for a 262 pilot was not venturing below the speed at which the jet engines provided a thrust advantage, saving maneuvering for speeds above this limit. If the pilot adhered to that rule then the lower drag & added thrust gained over the conventional types would give him quite an advantage, esp. in energy retention during maneuvers. 

Edited by Panthera

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Added the Me-109G6 and La-5FN to the C++ and BoX turn time comparison table I posted earlier. The figures in the table basically speak for themselves but here are some observations:

 

The G6 is like the G2 underperforming in-game although not by as much as the G2. The developers numbers on the La-5FN are pretty close to the C++ estimate but slightly on the conservative side. However, for some strange reason the La-5FN turn time is given at 320-340 Km/h IAS which is much higher than speed for best turn time which is closer to the 270 Km/h IAS just like for the other planes. Reducing the IAS from 320-340 Km/h to 270 Km/h will reduce the La-5FN turn time with about 1 s so it should be able to turn better in-game if you do this.

post-23617-0-30932800-1519482851_thumb.gif

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Me too Radick, Holtzauge's list agrees incredibly well with real life data and I honestly can't find any faults with it in terms of the data used. The only possible exception is wether the Fw190s clmax is correct, but I understand why he chose the number he did, it's the conservative choice in lack of better data and that's what an engineer should do.

 

In short I'd be a very happy man if Holtzauges list was duplicated ingame.

Edited by Panthera

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Well I did file a report a few days ago but no response so far but I'm assuming the developers have their hands full with the coming release so we'll see. BTW: I did this by sending some of them a joint PM outlining the ideas put forward in this thread but does anyone know if there is a more formal report system that should be used?

Edited by Holtzauge

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Well I did file a report a few days ago but no response so far but I'm assuming the developers have their hands full with the coming release so we'll see. BTW: I did this by sending some of them a joint PM outlining the ideas put forward in this thread but does anyone know if there is a more formal report system that should be used?

 

Just the original file claim of fault in FM with supporting documentary evidence instructions.

 

Not sure what you want to achieve though: if it is pointing out some specific ways in which the test results vary from RL documented test results - eg the 109 turns times, it has been mentioned that they are already aware of that.  If you want more generally to get the devs to check their modelling against your C++ model: good luck!

 

They will want to see your model - while not showing you theirs - and engineering pride will be involved.  ;)

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