Hawker Tempest turning performance

[Yak_Panther]

https://reports.aerade.cranfield.ac.uk/handle/1826.2/3233

[-=PHX=-SuperEtendard]

Found this one at the ww2aircraftperformance website. I wonder if it can be extrapolated towards the lower speed regimes to come up with good Clmax estimate based on listed stall speeds?




http://www.wwiiaircraftperformance.org/mustang/rae1501.html

Edited March 20, 2021 by -=PHX=-SuperEtendard

[unreasonable]

3 hours ago, -=PHX=-SuperEtendard said:

Found this one at the ww2aircraftperformance website. I wonder if it can be extrapolated towards the lower speed regimes to come up with good Clmax estimate based on listed stall speeds?




http://www.wwiiaircraftperformance.org/mustang/rae1501.html

 

Not really.  As you can see, the range of the speeds does not go far enough down: the manual gives a wider range at the low end, but not low enough. Even here, it is not clear that the extrapolation should be a straight line at high AoA. So it is hard to reconcile the stated IAS stall speeds with the PECs.

 

 

Edited March 20, 2021 by unreasonable

[Talon_]

On 11/21/2020 at 4:32 PM, Bremspropeller said:

Turning performance Tempest V vs Typhoon from 1943 (+7lbs boost available at this time).

 

Source:

http://www.wwiiaircraftperformance.org/tempest/Tempest-V_Eng-47-1658-C.pdf

 

 

 

 

Two more things:

 

- asking @LukeFF: Where did you find that the Tempest only carried 150rpg? All my sources (well, those sighted so far) only give the capacity of 200rpg, but no additional information about combat loadouts. Would an additional, optional incresed 200rpg loadout make sense?

 

- paging all the others, too (certaily including @Talon_ ) : Would a +13lbs option make sense for the Tempest on the Normandy map, given that most (all?) Tempest units were supposed to go V-1 hunting? Can't find any evidence for or against the use of the +13lbs setting during that timeframe.

 

V-1 chasing performed using modified Sabre IIA engines at +11lbs 3700rpm on 150 grade fuel.

[Aurora_Stealth]

Hi folks,

 

Just been doing some research for another thread and came across this: http://www.wwiiaircraftperformance.org/sl-wade.html

 

Thought this extract was worth sharing as its a revealing statement from a member of the AFDU test department, note the Thunderbolt II is just another name for the P-47 ( D )

 

Turning Circles

In circumstances where the ability to turn quickly or tightly are infinitely variable, and where two aircraft are nearly the same, such as the Tempest V and Thunderbolt II, a great deal depends on the ability of the pilots. Speed must be taken into account if the results are going to be of any real value.

 

For example, if a Tempest dives on a Thunderbolt with an overtaking speed of only 50 mph, the Thunderbolt will easily be able to avoid the attack by turning, although at the same speed in the hands of equally competent pilots, the Tempest will outmanoeuvre the Thunderbolt. This advantage, however, is no by any means so apparent at high altitudes, due to the greater engine efficiency of the Thunderbolt above 25,000ft.

 

Similarly, where low-altitude and high-altitude fighters are compared any advantage shown by the former will be reduced as the high-altitude fighter gets nearer to its best operational altitude. After taking all these considerations into account, the position of the aircraft relative to each other will be seen from the diagram.

 

Once again, the Spitfire maintains top place, followed by the Mustang, Meteor, Tempest and Thunderbolt. Too much regard to this order should not be paid, particularly by the individual who will angrily recall the occasion when he out-turned a Meteor when flying his Tempest. This sort of thing is inevitable, but we can only repeat that where the circumstances are common to both aircraft, these positions are not far wrong.

 

First prize to the Spitfire XIV.

Edited April 19, 2021 by Aurora_Stealth

[-=PHX=-SuperEtendard]

There is also the evaluation of the Tempest Mk II with the Centaurus engine that says the plane retained the maneuverability of the Mk V, both with similar turning circles, but then proceeds to say it always out turns the P-47D. But once again there is no information on the altitude and power settings used by the planes.


 

[HawkerMkIII_]

And there is also this test I uploaded earlier, but I'll post it again for the sake of it, where it says the Tempest ran rings around the P-47, but was slightly less maneuverable than the Mustang, I think this one is the most convincing, as it seems the one that makes the most sense considering  the size of the Tempest. 

 

 

Source: This book https://b-ok.lat/book/755164/d84c99?dsource=recommend&regionChanged=&redirect=200333741 

 

 

 

Edited April 19, 2021 by -332FG-Razor_

[6./ZG26_Klaus_Mann]

Ran Rings around = Larger Turning Circle.

Or is it one of those things were Americans are "challenged" when it comes to Communicating clearly because they are completely oblivious to the fact that many american Idioms are idiotic to anyone not American?

 

Edited April 20, 2021 by 6./ZG26_Klaus_Mann

[Legioneod]

25 minutes ago, 6./ZG26_Klaus_Mann said:

Ran Rings around = Larger Turning Circle.

Or is it one of those things were Americans are "challenged" when it comes to Communicating clearly because they are completely oblivious to the fact that many american Idioms are idiotic to anyone not American?

 

I take ran rings around to mean it was better in the turn and was able to out pace it in the turn.

 

Ran rings around = faster

 

same way running circles around someone means you are better or faster.

 

 

Edited April 20, 2021 by Legioneod

[HawkerMkIII_]

It is quite confusing indeed, but my logic is that they mean it had a better turn circle than the P47, because if it's ''slightly less'' than a Mustang, it would make sense it would be better than the P-47, because the P-47 is known for not having the best turning ability .

 

 

2 minutes ago, Legioneod said:

I take ran rings around to mean it was better in the turn and was able to out pace it in the turn.

 

Ran rings around = faster

 

 

I think just the same.

[354thFG_Leifr]

20 hours ago, 6./ZG26_Klaus_Mann said:

Ran Rings around = Larger Turning Circle.

 

To run rings around someone is a British idiom, and it means to be better in every regard than something else. The source you refer to would, in this instance, mean that the Tempest was regarded as being the better aircraft in every capacity than the Thunderbolt, but slightly inferior to the Mustang.

[DD_Arthur]

23 hours ago, 6./ZG26_Klaus_Mann said:

Ran Rings around = Larger Turning Circle.

Or is it one of those things were Americans are "challenged" when it comes to Communicating clearly because they are completely oblivious to the fact that many american Idioms are idiotic to anyone not American?

 

 

“Ran rings around” is a very English term well understood by native English speakers Klaus.

In this context it refers to overall manoeuvrability.

[Yak_Panther]

While hunting for a primary source Cl for the Tempest. I came across the RAE report RM 2732. It contains a graph of Cl's for various aircraft including a Typhoon and The Tempest II.  https://reports.aerade.cranfield.ac.uk/handle/1826.2/3280

And From RM 2222

 

source: https://reports.aerade.cranfield.ac.uk/handle/1826.2/3233

Both reports seem to put the Cl below 1 for the Tempest and report 2732 gives the Typhoon a Cl max of 1.025.

Given the in game Tempest V's Cl max is 1.5. I was having an issue reconciling these reports. As we would expect the Typhoon to have a higher Cl but lower top speed, and Tempest II isn't identical to our Tempest V, however it's close. 

 

 So in light of these irregularities, I had the British National Archives pull and digitize RM Aero 1830, "Wind Tunnel Test with Slipstream on Tempest Models".  The results are very interesting.  They agree with previous quoted reports, and give a CL max of .969 to 1 for a Tempest V with the nose radiator.  The test were conducted at speed of 120 fps, giving a RE of  10^6.  I'm still waiting on another report.

Edited May 30, 2021 by Yak_Panther

[ZachariasX]

4 hours ago, Yak_Panther said:

Given the in game Tempest V's Cl max is 1.5. I was having an issue reconciling these reports.

Our ingame Tempest has probably a bit high of a Clmax. From description of more recent flight descriptions with the Fury it could probably be around 1.2, 1.3 at the most. Stated stall speeds in the PN would still be plausible when PEC is applied. 1.5, that I‘d consider a plausible Clmax for the Typoon.

 

The values stated in this report are measured on models, hence they might well differ more in that way from the theoretical infintie span values. Those are known qualities and should serve as base from where throwing guesses.

 

http://airfoiltools.com/airfoil/details?airfoil=tempest1-il

http://airfoiltools.com/airfoil/details?airfoil=tempest2-il

 

 

 

[Yak_Panther]

1 hour ago, ZachariasX said:

Our ingame Tempest has probably a bit high of a Clmax. From description of more recent flight descriptions with the Fury it could probably be around 1.2, 1.3 at the most. Stated stall speeds in the PN would still be plausible when PEC is applied. 1.5, that I‘d consider a plausible Clmax for the Typoon.

 

The values stated in this report are measured on models, hence they might well differ more in that way from the theoretical infintie span values. Those are known qualities and should serve as base from where throwing guesses.

 

http://airfoiltools.com/airfoil/details?airfoil=tempest1-il

http://airfoiltools.com/airfoil/details?airfoil=tempest2-il

 

 

 

The Sea Fury has a different wing than the Tempest V. 

The PEC for the Tempest is unreliable at the stall speed.

 

The polar on foils tools at a similar Reynolds number puts the Cl max at 1.15 at an Alpha of 13.25.  The RAE Tempest model has a Cl max of 1 at 13.69. So the model numbers are not a huge disparity from the 2d airfoils.  Given 2D airfoils over estimate Cl max because they do not account for the effects of the aspect ratio and fuselage interference.

http://airfoiltools.com/polar/details?polar=xf-tempest2-il-1000000

Short of either full scale wind tunnel tests or flight test with better instrument correction. That model test is the best primary source on the lift polar for the Tempest. The models used in these are substantive and can be quite large.  I'll attach a PDF of the rest of the report. If anyone one want to look at it all.

 

 

 

Tempest Aero Report 1830.rar

[Holtzauge]

7 hours ago, ZachariasX said:

Our ingame Tempest has probably a bit high of a Clmax. From description of more recent flight descriptions with the Fury it could probably be around 1.2, 1.3 at the most. Stated stall speeds in the PN would still be plausible when PEC is applied. 1.5, that I‘d consider a plausible Clmax for the Typoon.

 

The values stated in this report are measured on models, hence they might well differ more in that way from the theoretical infintie span values. Those are known qualities and should serve as base from where throwing guesses.

 

http://airfoiltools.com/airfoil/details?airfoil=tempest1-il

http://airfoiltools.com/airfoil/details?airfoil=tempest2-il

 

 

 

 

Yes, I agree and with the caveat of not having looked into this in more detail I would also place the Typhoon higher than the Tempest's ballparked Clmax of 1.2. Usually 1.3-1.4 is where most conventional aircraft of the time ended up and I can't offhand see any reason why the Typhoon with its even for its time thick NACA 2213-19 airfoil should come in lower and I would not use the R&M reports looking into stability and Clmax at compressibility speeds based on model tests to predict Clmax for full scale aircraft due to Re effects which are too low in model trials and have a large impact on Clmax results.

[ZachariasX]

1 minute ago, Holtzauge said:

Usually 1.3-1.4 is where most conventional aircraft of the time

True that. I'd just place it on the higher side of the non-slatted profiles. Your numbers are probably more like it.

[Holtzauge]

18 minutes ago, ZachariasX said:

True that. I'd just place it on the higher side of the non-slatted profiles. Your numbers are probably more like it.

 

Post 1: Absolutely: I would not be surprised if it was around 1.4. Should be much better than the Tempest anyway.

 

 

Post 2: Quick Xfoil run at Re=3E6 for NACA 2213 which was Typhoon's wing tip airfoil gives an impressive 2D Clmax of 1.75. The root is NACA 2219 which will have an even higher Clmax. It will be even higher Re IRL so even better than these results so maybe your first ballpark guess of 1.5 is not so far off the mark after all @ZachariasX

 

 

Post 3: ARGGGGH! WHY ARE POSTS STILL GETTING AUTOMERGED? WHEN ARE THEY GOING TO FIX THIS!!!!!!!!

 

Edited May 30, 2021 by Holtzauge

[sturmkraehe]

Hi! By curiosity: Numbers on CL, CD, Cm and what ever are thrown around this place but as far as I recall my aerodynamics lecture these numbers are normalized values for lift, drag forces, pitch moment and what ever normalized by dynamic pressure (= f(V, rho)) AND a suitable reference area. In principle I could just chose a reference area twice as large and would obtain half the lift coefficient but still have the same force. I hence retained from my aerodynamics courses that numerical values for CL, CD and so on are meaningless for comparison between different vehicles if the value of the reference area is not provided. as far as I know there's no convention of a specific numerical value, maybe on the type of reference area to be taken but this would vary from plane to plane.

 

[Holtzauge]

42 minutes ago, sturmkraehe said:

Hi! By curiosity: Numbers on CL, CD, Cm and what ever are thrown around this place but as far as I recall my aerodynamics lecture these numbers are normalized values for lift, drag forces, pitch moment and what ever normalized by dynamic pressure (= f(V, rho)) AND a suitable reference area. In principle I could just chose a reference area twice as large and would obtain half the lift coefficient but still have the same force. I hence retained from my aerodynamics courses that numerical values for CL, CD and so on are meaningless for comparison between different vehicles if the value of the reference area is not provided. as far as I know there's no convention of a specific numerical value, maybe on the type of reference area to be taken but this would vary from plane to plane.

 

 

The 2D Cl and Cd values etc. are actually very good numbers to compare different airfoils since they produce a dimensionless "goodness" number that actually is directly comparable between different airfoils. And it is not meaningless: The 2D Cl value for example can be envisioned as what you would get per unit area for a wing with infinite span, i.e. a wing without induced drag. If you did do tunnel runs you may remember that there were correction factors applied for tunnel blocking and "mirroring" effects from the walls from the wings circulation lift. In properly calibrated wind tunnel with good correction factors you can get the 2D lift Cl for a wing profile section mounted snugly in between the tunnel walls by doing the correct correction to measured data.

[unreasonable]

6 hours ago, sturmkraehe said:

Hi! By curiosity: Numbers on CL, CD, Cm and what ever are thrown around this place but as far as I recall my aerodynamics lecture these numbers are normalized values for lift, drag forces, pitch moment and what ever normalized by dynamic pressure (= f(V, rho)) AND a suitable reference area. In principle I could just chose a reference area twice as large and would obtain half the lift coefficient but still have the same force. I hence retained from my aerodynamics courses that numerical values for CL, CD and so on are meaningless for comparison between different vehicles if the value of the reference area is not provided. as far as I know there's no convention of a specific numerical value, maybe on the type of reference area to be taken but this would vary from plane to plane.

 

 

Wherever I have referred to the game's Clmax of whole planes, I am using the wing area as given in the tech specs page, AFAIK everyone else is following the same convention. This is, I think, except for the biplanes, the wing area including the section of fuselage directly  between the wing roots as seen from below. This measure also seems to match up with the convention used in most WW2 era documents.

 

So for comparison purposes it is reliable enough, but it is always worth checking with new sources that the definition of the reference area is the same.  If a different area is given it is easy enough to change the Cl accordingly.  

[Yak_Panther]

 

15 hours ago, Holtzauge said:

 

Yes, I agree and with the caveat of not having looked into this in more detail I would also place the Typhoon higher than the Tempest's ballparked Clmax of 1.2. Usually 1.3-1.4 is where most conventional aircraft of the time ended up and I can't offhand see any reason why the Typhoon with its even for its time thick NACA 2213-19 airfoil should come in lower and I would not use the R&M reports looking into stability and Clmax at compressibility speeds based on model tests to predict Clmax for full scale aircraft due to Re effects which are too low in model trials and have a large impact on Clmax results.

Just to be clear, both RAE 2732 with the polar for Typhoon and the Tempest, and RAE 2222. Are problematic for numerous reasons. Scaling (Reynolds effects) is one, the other also being use of Trimmed Cl in the reports. That is Cl where Cm =0. Which tends to be lower than Cl max.

 

However RM Aero 1830 is a much better source for Tempest Data. As the Reynolds numbers of the tests are noted and are comparable to flight conditions. The tests in this report were conducted 120 feet per second, Re= 10^6. And, 80 feet per second Re .65*10^6. The 120 fps (81 mph) test is comparable to the stall speed listed in noted in the Tempest V Pilot's Manual (85mph before PEC) and the in game stall speed of 150 kph (93mph). Also, the tests in  Report 1830 give both the Cl and Cm. So we know those Cl's are not trimmed Cl's as the Cm is not =  zero in the plots.

 

RAE Aero 1830 would put the Cl of the Tempest V in a 1g power idle stall around .9 to 1.1. Currently in game the Tempest V CL is ~ 1.5 based on the performance charts. IE at a weight of 4585 kg with a wing area of 27.81 m² with a stall speed of 150 KPH.

 

Given that CL of the Typhoon is probably around 1.5 and the wing area is 15% smaller than Tempest.

 

Source: https://reports.aerade.cranfield.ac.uk/handle/1826.2/3148

 

How do you resolve a Cl max for the Typhoon? The pilots manual for the Typhoon gives the stall speed at 11,120 lbs at 80-90 mph. That puts the Cl at 1.9 to 2.4.

 

The question is do we get?

1. Typhoon with a Cl ~1.9 and Tempest with Cl of 1.5, or

2; a Typhoon and a Tempest with a Cl of 1.5. Or

3. Tempest with a Cl of 1.1 and Typhoon with a Cl of 1.5?

 

The non empiric performance metrics of the Tempest begin to make sense if the aircraft has a Cl of 1.1. For example, The claim "There is very little difference in turning circles between the two aircraft (the 190 and the Tempest) . If anything a very slight advantage lies with the Tempest. "

http://www.wwiiaircraftperformance.org/tempest/tempestafdu.html

 

If the author of this report is talking about turn radius. The 190 with a Cl of 1.39 and the a Tempest with a Cl of 1.1 will have similar minimum turn radius. As turn radius is function of air speed. Where 

Radius =  V^2 / g* Sqrt (nz^2 - 1)

 

If we use standard load weights, from the game stats,  for the 190(4140 kg) and the Tempest (5221 kg).  Given their respective wing areas, a Tempest with a Cl max of 1.1 will stall at the approximately same speed as a 190 with a clmax of 1.39 and a wing area of 18.3m^2. Since both craft stall around the same speed, and turn radius is dependent on air speed.   The 190 and the Tempest with a Cl max of 1.1 would have the same turn radius. The non empirical comment, "very little difference in turning circles" begins to make sense if the Cl is correct for the Tempest and the metric is contextualized correctly.  

 

Just as an interesting note. The game's web spec sheet https://forum.il2sturmovik.com/topic/25993-aircraft-flight-and-technical-specifications-and-operational-details/

 

  Gives different data for the wing dimensions of the Tempest compared to some of the source material. The game, list the wing area as 27.81 m^2  or 299 square feet. Report 1830 has it 302.5 sq^2 feet or 28.10317m^2.

The game has the wing span listed as 12.5 meters or 41.01 feet, RAE aero 1830 has it at 42.9. RAF lists it at either 43.9 http://www.wwiiaircraftperformance.org/tempest/tempest-v-ads-sabre-IIa.jpg

 

or 41 feet.

http://www.wwiiaircraftperformance.org/tempest/Tempest_V_Sabre_IIB_ADC.jpg

 

The differences in area do not make huge difference in the performance though. 

 

Edited May 31, 2021 by Yak_Panther

[Holtzauge]

5 hours ago, Yak_Panther said:

<Snip>: However RM Aero 1830 is a much better source for Tempest Data. As the Reynolds numbers of the tests are noted and are comparable to flight conditions. The tests in this report were conducted 120 feet per second, Re= 10^6. And, 80 feet per second Re .65*10^6. The 120 fps (81 mph) test is comparable to the stall speed listed in noted in the Tempest V Pilot's Manual (85mph before PEC) and the in game stall speed of 150 kph (93mph). Also, the tests in  Report 1830 give both the Cl and Cm. So we know those Cl's are not trimmed Cl's as the Cm is not =  zero in the plots.

 

Not sure how you make that connection? Sure the air speeds (wind tunnel and IRL flight speeds) are comparable but they are not "comparable flight conditions" since the Re is quite different for the model and the actual aircraft which in stall conditions has a significantly higher Re (ballpark 6E6) than 1E6 as in the model trials, i.e. roughly 6 times larger. Since Re has a huge impact on Clmax I would be very hesitant to draw any conclusions on Clmax for either the Tempest or the Typhoon based on such wind tunnel trials.

 

[sturmkraehe]

15 hours ago, unreasonable said:

 

Wherever I have referred to the game's Clmax of whole planes, I am using the wing area as given in the tech specs page, AFAIK everyone else is following the same convention. This is, I think, except for the biplanes, the wing area including the section of fuselage directly  between the wing roots as seen from below. This measure also seems to match up with the convention used in most WW2 era documents.

 

So for comparison purposes it is reliable enough, but it is always worth checking with new sources that the definition of the reference area is the same.  If a different area is given it is easy enough to change the Cl accordingly.  

 

Thanks for making this clear. This is helpful.

 

Please allow me to suggest that when comparing CLs et al to just indicate the number of reference area used. For instance, if a plane with small wing area has a CL 1.1 at certain conditions and another plane has the same CL at the same conditions but which has a larger wing area the latter will be able to produce more lift under same conditions. 

(please don't take offence at my suggestion. It is just for getting a thorough understanding of all the numbers here)

Edited May 31, 2021 by sturmkraehe

[unreasonable]

15 hours ago, sturmkraehe said:

 

Thanks for making this clear. This is helpful.

 

Please allow me to suggest that when comparing CLs et al to just indicate the number of reference area used. For instance, if a plane with small wing area has a CL 1.1 at certain conditions and another plane has the same CL at the same conditions but which has a larger wing area the latter will be able to produce more lift under same conditions. 

(please don't take offence at my suggestion. It is just for getting a thorough understanding of all the numbers here)

 

No offence taken - the actual measured physical force is lift,as you said, the Cl is an index: but it is a useful comparative measure of the ability of the plane - or wing - to produce lift per unit area, and hence predict Vmin if you know weight and area. That is why it is a better comparison that looking at the total lift production: it is a measure of lift efficiency. 

 

All the game data is there and anyone can compile a spreadsheet of comparative values, ( I am a bit surprised that nobody else has done this already).  I do not think it the area needs restating every time any more than the weight needs restating every time, provided that you are working from a known, shared database. I do however agree that when comparing with outside sources the source reference area should be checked.

[sturmkraehe]

8 hours ago, unreasonable said:

 

No offence taken - the actual measured physical force is lift,as you said, the Cl is an index: but it is a useful comparative measure of the ability of the plane - or wing - to produce lift per unit area, and hence predict Vmin if you know weight and area. That is why it is a better comparison that looking at the total lift production: it is a measure of lift efficiency. 

 

All the game data is there and anyone can compile a spreadsheet of comparative values, ( I am a bit surprised that nobody else has done this already).  I do not think it the area needs restating every time any more than the weight needs restating every time, provided that you are working from a known, shared database. I do however agree that when comparing with outside sources the source reference area should be checked.

I agree that CL is sufficient to evaluate plane performance per unit area. However, we are discussing turn performance of various planes that come all with their own weight and size and therefore I think it may be not sufficient to just compare performance per unit area because turn performance is the integral of the entire system and hence absolute values are more relevant I think.

[HawkerMkIII_]

Bruh

[Mitthrawnuruodo]

3 hours ago, sturmkraehe said:

However, we are discussing turn performance of various planes that come all with their own weight and size and therefore I think it may be not sufficient to just compare performance per unit area because turn performance is the integral of the entire system and hence absolute values are more relevant I think.

 

Wing loading, span loading, and power loading let us compare performance in a way that doesn't depend on absolute size and weight. You're right that lift coefficients alone don't tell the whole story.

 

Lift coefficients are the most interesting because they depend on the wing design and therefore aren't trivial to determine, unlike the other parameters.

[-=PHX=-SuperEtendard]

The Typhoon is in the game now, and using @unreasonable method with the in game specs table, with the minimum and maximum weight listed stall speeds the Typhoon's Clmax would be 1.66

Flying it myself I sort of get a stall speed at 1G around 154-152 km/h with the standard weight of 4915 Kg, which would also indicate a Clmax of around 1.66-1.70.

Looks like the Typhoon is closer to what's expected given @Holtzauge 's simulation of 1.75 for the ideal infinite airfoil. Maybe it could be a bit lower? for sure much closer to what it should be than the Tempest.

I wish the Tempest was revisited in this regard.

Edited June 1, 2021 by -=PHX=-SuperEtendard

[unreasonable]

Yes, I get the same...  it looks like the relative result for Typhoon vs Tempest is reasonable, but there is a case that they are both too high and hence stall speeds too low.

 

Typhoon manual gives stall speed with ammunition and nearly all fuel expended (9900lbs) as 75-80 mph IAS.  = Cl max 2.16 - 2.46

 

So you can see the team has already made a considerable correction of 9-14 mph to the manual's Vmin   Personally I do not see why they did not just use the RAE's generic correction curve and correct 20mph, which would get you into the range more consistent with the other aircraft.

 

Of course this may have some other unintended consequences for the FM, so I am not sure if that would be the best solution.

[CountZero]

Did anyone manage to brake a wing on Typhoon like its easy to do on Tempest ? i try today few times in deep dives and max pull up and even with 10G shown on HUD wings are ok. 

 

[Holtzauge]

I just realized that using the same reasoning as for the Tempest the Typhoon should land at roughly 1.35 in Clmax, i.e. close to many other aircraft already modeled.

 

Why? Well I just remembered that I ran the NACA 23012 profile used on the Fw-190 etc. at high RE in Xfoil and that gave a 2D Clmax of 1.75 for that profile as well even though it is thinner than on the Typhoon. However, thickness and nose radius is not everything and the Typhoon is closer to symmetrical while the 230-series has more camber and a drooping leading edge (a bit like a LE flap ) so it does pretty well even though it's thinner.

 

So using 1.35 as a base and calculating in the same way as for the Tempest as was done here earlier in this thread:

 

Estimated Typhoon Clmax= 1.35*1.75/1.75=1.35

Edited June 2, 2021 by Holtzauge

[RedKestrel]

55 minutes ago, Holtzauge said:

I just realized that using the same reasoning as for the Tempest the Typhoon should land at roughly 1.35 in Clmax, i.e. close to many other aircraft already modeled.

 

Why? Well I just remembered that I ran the NACA 23012 profile used on the Fw-190 etc. at high RE in Xfoil and that gave a 2D Clmax of 1.75 for that profile as well even though it is thinner than on the Typhoon. However, thickness and nose radius is not everything and the Typhoon is closer to symmetrical while the 230-series has more camber and a drooping leading edge (a bit like a LE flap ) so it does pretty well even though it's thinner.

 

So using 1.35 as a base and calculating in the same way as for the Tempest as was done here earlier in this thread:

 

Estimated Typhoon Clmax= 1.35*1.75/1.75=1.35

Give it to me straight doc...what's it all mean? I think this means that the Typhoon's behaviour is closely in line with the rest of the planes in the sim, with the Tempest still being an outlier.
 

[Holtzauge]

47 minutes ago, RedKestrel said:

Give it to me straight doc...what's it all mean? I think this means that the Typhoon's behaviour is closely in line with the rest of the planes in the sim, with the Tempest still being an outlier.
 

 

Well for me it means that the Clmax for Tempest and Typhoon in power off conditions both seem a bit on the optimistic side in-game while the Spitfire is at 1.36, the Fw-190 at 1.35 and the Me-109 at circa 1.4 so all well and good. However, the Tempest is as far as I know at 1.5 in game and as per reasoning above should be closer to 1.2 and the Typhoon I gather is now almost 1.7 when it looks like it most likely should be closer to 1.35 IRL also as per reasoning above.

[Guest deleted@258843]

6 hours ago, CountZero said:

Did anyone manage to brake a wing on Typhoon like its easy to do on Tempest ? i try today few times in deep dives and max pull up and even with 10G shown on HUD wings are ok. 

 

 

First time I tried it out I ripped a wing off fairly easily after a dive and a hard pull.

[unreasonable]

14 hours ago, Holtzauge said:

 

Well for me it means that the Clmax for Tempest and Typhoon in power off conditions both seem a bit on the optimistic side in-game while the Spitfire is at 1.36, the Fw-190 at 1.35 and the Me-109 at circa 1.4 so all well and good. However, the Tempest is as far as I know at 1.5 in game and as per reasoning above should be closer to 1.2 and the Typhoon I gather is now almost 1.7 when it looks like it most likely should be closer to 1.35 IRL also as per reasoning above.

 

If you take the upper end of the (10mph)  speed range given for the cleanest weight from the Tempest and Typhoon manuals, and adjust as per the RAE generic PEC chart, gets:

 

Tempest +17 at 90mph IAS = 1.31 

Typhoon +19 at 80mph IAS = 1.43

 

ie there is a rational path from the manual data to something similar to your proposal, though still a bit higher, which is also more or less in line with the rest of the plane set, but you have to use the RAE PEC. (Reproduced below).

 

The manuals' PEC tables match up very roughly to the curve in the range where they are given, but it looks as though they have been simplified to give a straight line, perhaps to make the pilots' calculations easier.  

 

So that is fairly circumstantial, but unless someone can find the actual source, I would be happy to go with a plausible explanation of the phenomenon.

 

 

 

Edited June 3, 2021 by unreasonable

[-=PHX=-SuperEtendard]

On 6/2/2021 at 2:48 PM, Holtzauge said:

Why? Well I just remembered that I ran the NACA 23012 profile used on the Fw-190 etc. at high RE in Xfoil and that gave a 2D Clmax of 1.75 for that profile as well even though it is thinner than on the Typhoon. However, thickness and nose radius is not everything and the Typhoon is closer to symmetrical while the 230-series has more camber and a drooping leading edge (a bit like a LE flap ) so it does pretty well even though it's thinner.

Is this the 190's wing tip airfoil as well? I wonder if there could be a way to take into account the different airfoils of the wing and get to a sort of average ideal value.

Edited June 5, 2021 by -=PHX=-SuperEtendard

[Holtzauge]

10 hours ago, -=PHX=-SuperEtendard said:

Is this the 190's wing tip airfoil as well? I wonder if there could be a way to take into account the different airfoils of the wing and get to a sort of average ideal value.

 

The Fw-190 had the same airfoil, the NACA 230 series with a 13.5 % thickness at the root and a 9% thickness at the tip. It also had a somewhat unconventional washout IIRC with a progressively lower aoa towards the tip and then a constant 2 deg from some station at the ailerons as I remember it. However, these are detail and most planes follow the principle of progressively more washout and thinner profiles towards the tip.

 

But the point I was trying to make earlier on in this thread is that once you know the wing profile 2D Clmax you can use this to get an estimate of the aircraft's Clmax just like I did earlier for the Tempest to arrive at circa 1.2. Now it happens that the Clmax on 2D level for both the Typhoon and the Fw-190 are in the order of 1.75 and since we know the Fw-190 is at 1.35 ballpark we can be pretty sure that the Typhoon is close to that as well.

 

Sometimes a picture explains better and the below figure shows in principle how it looks on the Fw-190 and Typhoon: The lift distribution on the wing will be roughly as I've drawn it and the shaded areas "balance" and is the reason you multiply the wing area by this balanced 3D Cl and not the profile's Clmax of 1.75.

 

So to calculate a "generic" ballpark Clmax for a WW2 fighter once you know the 2D Clmax:

 

Clmax_estimated= 2D_Clmax_profile* 1.35/1.75

 

 

Edited June 6, 2021 by Holtzauge

[sturmkraehe]

1 hour ago, Holtzauge said:

 

The Fw-190 had the same airfoil, the NACA 230 series with a 13.5 % thickness at the root and a 9% thickness at the tip. It also had a somewhat unconventional washout IIRC with a progressively lower aoa towards the tip and then a constant 2 deg from some station at the ailerons as I remember it. However, these are detail and most planes follow the principle of progressively more washout and thinner profiles towards the tip.

 

That the AoA is slightly lowered towards the wing tip was and is not so uncommon. The Spit too had these cranked wings and afaik some more modern Pipers employ this technique too in order to maintain airflow  on the ailerons in situations when the inner parts of the wings have already stalled. BTW this is not so negligible as one might think. During my study I visited a course that implied some measurements during flight in small aircraft. One flight was dedicated to demonstrate airflow in near stall conditions. This specific flight was executed in a Piper (low wing configuration). The entire wings were covered with 10 cm threads glued to the top side so that airflow could be visualized in real life. The pilot then climbed to altitude and drove the piper to the stall limit (both low speed and high speed). We students could observe that in the cranked section near the wing tip the airflow was still attached (signaled by the threads still smooth on the surface) whereas in the inner section of the wing the threads were detached from the surface indicating detached air flow. What surprised my that about only 1/3 of the wing span maintained attached airflow and the plane was still controllable and flew (a bit shakey though) and 2/3 of the wing was already stalled. As I was sitting in the rear I could not tell about altitude loss here but if so it was small as I did not notice any descernable descent motion.

Edited June 6, 2021 by sturmkraehe

[Yak_Panther]

The Tempest high speed wind tunnel tests are in and they are interesting. The tests were conducted on a scaled model of the Tempest across a range of mach and Reynolds numbers. While obviously not the ideal case, eg, a  full scale  service condition  wind tunnel, the tests do provide an insight into the Cl max of the Tempest.

 

A set of tests to determine the maximum lift coefficient were conducted at an Re of 4.04 to Re 4.68. However the full model was not tested in these conditions. The model was tested without the tail and the wing alone was tested. Therefore these represent the highest maximum lift coefficients for the Tempest at the given speeds and Reynolds numbers.   

 

The maximum Cl for the wing is  ~ 1.21 at mach .17, Re of 4.68e6. At an Re of 4.04e6 mach .2 the maximum Cl for the wing is 1.19

 

Tests with fuselage and wing combo

 

 

Also put the Cl max around 1.22. 

 

Scaling and Comparative Analysis. 

From an analytical view point, the best state of data presented in this report is the 3-d wing Cl polar. So I will use that data as the basis for a comparative analysis. 

 

The Cl max for the in game 190 was derived by a comparison of the full scale tests at the Chalais-Meudon wind tunnel to some other sets of data. The Chalais-Meudon wind tunnel tests were conducted with a Re of 4.6e6 and yielded a Cl max of 1.3. Since the Re is still below the flight condition the Cl max had to be increased to account for the difference in Reynolds numbers. The Cl, in game, for the Fw 190 is ~ 1.39. In- game stall conditions result in a Re  ~ 5.7 at a speed of 170 kph. Mach .13 The amount of Cl max added to the Chalais-Meudon wind tunnel test was based on a comparison of aircraft with similar aerofoils and some wind tunnel tests of a wing with a similar profile to the 190.

 

I have 3 sources that will put the Cl max of the 3-d Fw190 wing around ~ 1.5 One is a paper on a CFD analysis of world war 2 aircraft, that's been around for awhile. It contains a sectional lift distribution of the 190's wing at the 1g stall and notes the Cl max of the aircraft as 1.5. 

https://www.researchgate.net/publication/293706348_CFD_evaluation_of_three_prominent_World_War_II_fighter_aircraft

 

The second is a document on the wing construction of the FW 190. Which notes the same Cl max of the wing alone as 1.5

 

The third is test the NACA of a 3-d wing with the same airfoils as the Fw-190.  https://digital.library.unt.edu/ark:/67531/metadc61423/

Above: from NACA L5G10

 

The Cl max of FW-190’s 3-d wing results in an aircraft of ~1.38, due to fuselage interference, loss of Cl to trim, ect. This works out to about a 10% reduction from the 3d wing’s Cl ~1,5 to ~ 1.38.  Lets evaluate the Tempest’s wing and see if it's a good candidate to apply the same process of scaling to. 

 

To evaluate if changes to Reynolds numbers are likely to have a dramatic effect on the Tempest’s wing compared to the 190’s wing. We’ll compare the relationship between increasing the Reynolds number and the lift coefficient on the Fw-190’s 2-d aerofoils to the 2-d aerofoils on the Tempest’s wing. We will see that scaling from a Re of 4.5 to 6.5 has marginal effect on the lift coefficient for both airfoils.  We’ll use X foil and compare the 2d sections at the Tempest wind tunnel test conditions (Re 4.6) Vs the likely 1g stall condition of the Tempest (Re 6.5). 

 

The Fw-190s wing root aerofoil is a NACA 23015. At a Re of 4.5e6, mach .13 the Cl max of this airfoil is 1.8.

 Increasing the Re to 6.5e6 at the same speed only increases the Cl by .04 to 1.84 

 

The wing root aerofoil of the Tempest has a Cl max of 1.51 at an RE 4.5e6, mach .13. 

 

Increasing the RE to 6.5e6 , increases the Cl max of the aerofoil to 1.57. 

 

Reynolds scaling between the two airfoils is not dramatically different. Which makes sense, given that their thickness and the location of it, is relatively similar.

 

 

And the way foil thickness can govern Reynolds effects.

 

So the scaling effects (RE) between both airfoils will be relatively similar.  So scaling the CL in a manner similar to the 190's seems fine.

 

.Given the effects of scaling Reynolds numbers from 4.5e6 to 6e6 on the 2-d aerofoils.  We could assume the Cl max of the 3d wing of the Tempest would increase at most .06. Thus giving the 3-d wing alone a Cl max of 1.27 

 

 For simplicity's sake assume the effect of the fuselage on the lift coefficient for both aircraft is similar. Which would give a Tempest  a Cl of 1.1 to 1.2 

 

The same approach was applied to the 190 based on the F6F Hellcat to yield  the current Cl max for the 190. 

 

Above: From NACA L5B13b

 

Currently, in game,  the Tempest has the same Cl max as  the 2/d wing root aerofoils. Given wind tunnel tests of 3d wing shows a Cl max of 1.22 at an Re 4.6e6.  There is a sound basis for reducing the Cl max of the Tempest to 1.1-1.2.

Edited June 12, 2021 by Yak_Panther
spelling and photo update.