Hawker Tempest turning performance

[ZachariasX]

1 hour ago, Holtzauge said:

I just did a quick check with my C++ model of the Tempest and I get about 21 s at 1 km altitude for a turn with the Sabre at +11 boost

That would match rather closely with the 20s from the Tempests manual mentioned by @Roland_HUNter. Let‘s see what a fix will bring.

 

[Roland_HUNter]

7 hours ago, ZachariasX said:

The Tempest has far better controls at high speeds due to flettner tabs. It *is* far better to pilot at high speeds than almost any other plane. It is Britains apex fighter of WW2 for good reason.

 

The problem is the lift coefficient of the wing and (induced) drag. In the sim, it most likely has the effective clmax derived by the minimum speed stated in the PN. However, these figures can be deeply misleading, as this tells you nothing about the control you still have at that speed nor the sustainability of this flight configuration, as induced drag rises considerably („coffin corner“).

 

This is for instance why the P47 on one side is a great plane to fly, but if you get slow that is the end of you. There, all the thousands of hp will not help anymore. You‘re not getting away with this at that moment as you would in a Spit or a 109.

 

The Tempest wing profile is specifically designed for low drag. This goes against high AoA. Right now in the game, The Tempest is both king of one circle and two circle fights, while in the real world it is designed for optimum performance (and control) at high speeds. Sydney Camm had learned his lesson from the Typhoon debacle. The devs made their task way too simple for designing the FM of that aircraft.

 

I hope @Holtzauge will at some point come up with a more exact depiction of the situation in future work.

The simulation of the game is diametrically opposed to the real meaning. (see the very first diagram in the topic)
There is nothing to discuss.
Also, as you may have read, the C++ modeling says the machine turns too well.
No need to talk about the wing here.
That machine is 5+ tons. And with wings like that it shouldn't turn that well.

[ZachariasX]

1 hour ago, Roland_HUNter said:

The simulation of the game is diametrically opposed to the real meaning. (see the very first diagram in the topic)
There is nothing to discuss.
Also, as you may have read, the C++ modeling says the machine turns too well.
No need to talk about the wing here.
That machine is 5+ tons. And with wings like that it shouldn't turn that well.

You are not helping your case.

 

The Tempest has a relatively low wing loading and the wing has a relatively low clmax, rather alike the Spitfire which is a great turner that flies a small circle. The Tempest also is indeed one of the fastest around the circle, yet it has to do this at a faster pace, hence it will fly a larger circle at probably a lower AoA. 

 

The game mainly makes a mistake by giving the plane excessive AoA authority and clmax to make it a great one circle fighter, when in fact hitting the brakes and do a stalling contest is not really a viable strategy in the real plane as it is in the game. Knowing the wing profile and what it was designed for helps.

 

It is the *radius* that is the main problem (the one circle, nose to nose fight is a radius fight) less so the *rate* (the two circle, a rate fight) where it is maybe 2 seconds (10% optimistic) off in the game.

 

That the plane is heavy is no problem at all if you are fast, but when slow it becomes a problem exponentially. So, when bothering the devs, it helps being specific about the problem. And for that, I’d say knowing the wing is more important than old sketches when you want to quantify the problem. And I wonder how @Holtzauge‘s simulations would return those radii, especially say at low, mid and high altitude.

 

Given the lightness of control at high speeds and the high Mach number of the wing, it should indeed be in its own leage as long as you are fast and low enough for the engine to not run out of breath. But not during the prophanging contest, where it excells now as well in the game. The FM we have now is not „very wrong“, it does however have a specific flaw that needs adressing.

 

If you just decrease the clmax to raise the 18 s or so turn time to 20 s but leave the rest, you cure very little of the situation we have now. We had that kind of corrections in the old days, bringing us „The Patch“. Nobody wants such an episode again.

 

Trust me, things are not trival and there‘s lots to discuss if you are to engineer a good solution.

[=MERCS=JenkemJunkie]

Is there any chance that any improvements to the tempest would also end up in the typhoon too? I can feel a lot of the tempest strangeness in the typhoon FM, but it's not nearly as exploitable and talked about due to the much harsher stall behavior.

[ZachariasX]

8 hours ago, =MERCS=JenkemJunkie said:

Is there any chance that any improvements to the tempest would also end up in the typhoon too? I can feel a lot of the tempest strangeness in the typhoon FM, but it's not nearly as exploitable and talked about due to the much harsher stall behavior.

The Typhoon is different as it has a very thick and long wing. The Typhoon was excellent at flying circles and terrible at rolling. The thing it shares with the Tempest is that you absolutely have to maintain a higher minimum speed compared to lighter aircraft despite his big wing. This required some readjustment for pilots who were used to the (Merlin) Spit which is excellent in slow speed maneuvering, no comparison for instance with even a Mustang. And when I say excellent, I mean you can really work the stick without the airspeed dropping below 100 mph as fast as you can say a four letter word. The Spit can do at 160 mph what the Mustang does at 200 mph. Generally, in the real Mustang you don‘t go below 200 mph if doing somewhat fancy maneuvers is your plan, even tough in principle it flies down to a speed of 100 indicated. It really catches breath above 250 mph.

 

In the game, it is usually the slow speed performance that is exploited. At slow speeds, induced drag rises exponentially. Sublte errors in FM design may have strong effects there.

 

Greg has a video out on drag, P51 vs Mustang where he illustrates how drag is a very relative thing.

[Holtzauge]

On 5/25/2024 at 11:21 PM, ZachariasX said:

The Tempest has a relatively low wing loading and the wing has a relatively low clmax, rather alike the Spitfire which is a great turner that flies a small circle. The Tempest also is indeed one of the fastest around the circle, yet it has to do this at a faster pace, hence it will fly a larger circle at probably a lower AoA. 

 

And I wonder how @Holtzauge‘s simulations would return those radii, especially say at low, mid and high altitude.

 

Yes, the Tempest needs to keep the speed up to get best turn time and can't compete with the Spitfire in turn radius. Some C++ simulated numbers for 1 km altitude:

 

Spitfire Mk 9 Merlin +18 boost: Turn time circa 17 s, radius around 215 at 285 km/h TAS

 

Tempest Mk 5 Sabre +11 boost: Turn time circa 21 s, radius around 305 m at 325 km/h TAS

 

This means that a Tempest will have about the same turn time as a Bf 109G6 (at 1.3 ata Steig & Kampfl.) at this altitude, but that both the Spitfire and Bf 109 will be turning at lower speeds and consequently with smaller radii.

 

 

Edited May 27, 2024 by Holtzauge

[Ace_Pilto]

I've been reading these "turn performance" threads since the 90's. When are you boys going to learn that turning is for losers. Speed, acceleration dive and climb beats defensive turning. There's no point in gooning over turn radius/rate etc. Just fly away and find another sucker. Speed is life!

Edited May 27, 2024 by Ace_Pilto

[Ace_Pilto]

To elaborate further, the book might say you can turn X units in S second but where was that figure produced? Not in combat, it was made by some nerd in perfect conditions with a clipboard and stopwatch. Can you get the book rated performance in combat? Probably not. You can only do what YOU are capable of. The chances of you becoming competent enough to get the max performance out of an aircraft only occur when you realise that. If I had a dollar for every one of these goofy performace threads where people argue the semantics of what is basically aeronautical archaeological science I'd be a rich man.

 

Why not ask "How do I get MORE out of aircraft X?" instead of debating meaningless figures from questionable origins? You might benefit more from having the humility to say that "This aircraft does not perform like I expected, what am I doing wrong?"

[1PL-Husar-1Esk]

2 hours ago, Ace_Pilto said:

I've been reading these "turn performance" threads since the 90's. When are you boys going to learn that turning is for losers. Speed, acceleration dive and climb beats defensive turning. There's no point in gooning over turn radius/rate etc. Just fly away and find another sucker. Speed is life!

Yeah, buy in duel scenarios, the final kill is made by a plane which are performing 1c or 2c maneuver, so having those right is essential. Plus those don't came from spreadsheet but from others factors. 

[=MERCS=JenkemJunkie]

3 hours ago, Ace_Pilto said:

I've been reading these "turn performance" threads since the 90's. When are you boys going to learn that turning is for losers. Speed, acceleration dive and climb beats defensive turning. There's no point in gooning over turn radius/rate etc. Just fly away and find another sucker. Speed is life!

At some point even if you yourself do nothing but camp up high and fly away, there's always going to be someone camping above you to force you into a fight, and at that point you'll be glad you've read Shaw. Also some people just enjoy dogfighting, it's not strange to want to dogfight in a plane game.

3 hours ago, Ace_Pilto said:

To elaborate further, the book might say you can turn X units in S second but where was that figure produced? Not in combat, it was made by some nerd in perfect conditions with a clipboard and stopwatch. Can you get the book rated performance in combat? Probably not. You can only do what YOU are capable of. The chances of you becoming competent enough to get the max performance out of an aircraft only occur when you realise that. If I had a dollar for every one of these goofy performace threads where people argue the semantics of what is basically aeronautical archaeological science I'd be a rich man.

 

Why not ask "How do I get MORE out of aircraft X?" instead of debating meaningless figures from questionable origins? You might benefit more from having the humility to say that "This aircraft does not perform like I expected, what am I doing wrong?"

This is a sim where the planes are meant to mimic the real ones, it's a pretty black and white issue that when a plane is modeled wrong then time permitting it should be fixed. 

[ZachariasX]

2 hours ago, Ace_Pilto said:

I've been reading these "turn performance" threads since the 90's.

It seems then this is the first one for you, where folks want to reduce some of the current capabilities.

 

2 hours ago, Ace_Pilto said:

There's no point in gooning over turn radius/rate etc.

At least my latest comments concern the actual aircraft. I haven‘t played the game in a while, but if Gavrick gives it another look, I‘m interested to see what he comes up with. Turn radii are a prominent metric to illustrate the aerodynamic properties of an aircraft with lots of dependencies.

 

2 hours ago, Ace_Pilto said:

Just fly away and find another sucker.

Find servers that let you do that long term (and remain online). Each plays the game as they like. As for me, see above.

 

1 hour ago, Ace_Pilto said:

To elaborate further, the book might say you can turn X units in S second but where was that figure produced?

The laws of aerodynamics produce facts, not opinions.

 

1 hour ago, Ace_Pilto said:

Can you get the book rated performance in combat?

You could, but you probably won‘t. But the book rated performance defines what you can make from it in combat best case. It *is* important, even if you can‘t really fly the aircraft.

 

1 hour ago, Ace_Pilto said:

You can only do what YOU are capable of.

If I can do things easily that the laws of aerodynamics rule out, then something IS wrong.

 

2 hours ago, Ace_Pilto said:

If I had a dollar for every one of these goofy performace threads where people argue the semantics of what is basically aeronautical archaeological science

What is? A game not reflecting reality („aeronautical archaeological science“)?

 

Again, my comments are about the real aircrafts capabilities. The game developers do as they do and you play as you play.

 

Let me repeat: The aerodynamic capabilities of an aircraft are not subject to opinions. They are based on scientific facts. I understand that, historically, in such threads this is often not understood. So, sorry for triggering you but emotionally it is your burden to carry. I actually would understand if you put such threads on your block list as I also find most of them not all that productive, as it is getting increasingly popular mistaking opinions with facts. That is something I can agree on.

[Holtzauge]

@Ace_Pilto: I don't think anyone is going to argue with you about speed and climb not being the most important: From WW1 and on they were the main drivers and soared to the top of the list in basically all procurement specifications.

 

And that was how it was for a long time until people like Boyd tried to get the top brass in the Pentagon to understand that there is more to it than that. I wrote a bit about this on my homepage here.

 

So yes, speed and climb are important. But unless you have a plane that that is good at turning as well you are like a man with a hammer seeing nails everywhere. Or how else do you account for the  success of the F-16? It's still here today and in many ways the yardstick against which everything else is measured. 

 

Finally, I think you should show more respect to the "nerds with the clipboards and stopwatches": After all, they are the ones who provide all the fighter pukes with Breitlings, big egos and immaculate mustaches with a ride to sit in, in the first place. 

 

 

 

 

Edited May 27, 2024 by Holtzauge

[Ace_Pilto]

Hey I'm only yanking your chain. I don't mean any actual disrespect, it's just the way I am.

[Ace_Pilto]

I'm a big believer in Boyd's OODA loop. You get a good grasp of Boyd and you can outfight any opponent, no matter the performance of their aircraft relative to yours. I just don't want to see a bunch of lads looking for revisions that, while they may be technically correct, will never come. You have to work with the tools you are given so why not focus on ways of making the things that you have in your hands right now work better?

[Roland_HUNter]

1 hour ago, Ace_Pilto said:

I'm a big believer in Boyd's OODA loop. You get a good grasp of Boyd and you can outfight any opponent, no matter the performance of their aircraft relative to yours. I just don't want to see a bunch of lads looking for revisions that, while they may be technically correct, will never come. You have to work with the tools you are given so why not focus on ways of making the things that you have in your hands right now work better?

Are you seriously asking me to give you an example?
Fw-190 roll rate?
I mean, no offence, but if a car can go 180 km/h, but for some report, only 170, it's not my fault.

I think you would agree with that.

[Ace_Pilto]

No. If a car can do one thing and if you can make it do one thing are two separate concepts. In combat you only have the parameters you can work with.

What can YOU get out of it, and how can you get MORE out of it depend upon more than yourself.

Instead of expecting the developers to fix your perceived shortcomings. look to your fellow pilots.

[Roland_HUNter]

6 minutes ago, Ace_Pilto said:

No. If a car can do one thing and if you can make it do one thing are two separate concepts. In combat you only have the parameters you can work with.

What can YOU get out of it, and how can you get MORE out of it depend upon more than yourself.

Instead of expecting the developers to fix your perceived shortcomings. look to your fellow pilots.

I think you know what the word META means....

[Ace_Pilto]

Things are what they are and, unless you ground yourself in a basic reality then you are flying an aircraft made of hopes and dreams. 

2 minutes ago, Roland_HUNter said:

I think you know what the word META means....

I do indeed and META should not be a factor in aerial combat. I am very anti-meta to my core. Meta destroys simulation and makes games tedious and predictable.

So tactics and co-operation are the answer to the meta menace. Like I said before, aircraft are not put there to be gooned over. They are tools to be employed. Work as a team. Co-ordinate. War is not fought in 1v1 duels. It's a contest of dominance.

[=MERCS=JenkemJunkie]

I can see the logic of that in a different context, but the tempest is really in a league of its own in terms of FM flaws. It flys under its own laws of physics and isn't something players should have to adapt to or crutch on.

Pointing flaws out in here has lead to fixes before, and a fix is already scheduled for the tempest, so its not true to say that its pointless to try to change things.

[Holtzauge]

4 hours ago, Ace_Pilto said:

Hey I'm only yanking your chain. I don't mean any actual disrespect, it's just the way I am.

 

And no offense taken! And I hope you see my response as the banter it was meant as. But really, on a more serious note, you were taking things to an extreme with the speed and climb comment and without good boffins designing a good and competitive airplane even hot shot pilots will strike out.

 

4 hours ago, Ace_Pilto said:

I'm a big believer in Boyd's OODA loop. You get a good grasp of Boyd and you can outfight any opponent, no matter the performance of their aircraft relative to yours. I just don't want to see a bunch of lads looking for revisions that, while they may be technically correct, will never come. You have to work with the tools you are given so why not focus on ways of making the things that you have in your hands right now work better?

 

Yes, Boyd was a visionary in many ways, not only concerning the manouverability part and the re-introduction of turn performance into the mix for a great fighter. TBH, I think his famous OODA loop is very reminiscent of Erich Hartmann's approach as well: Study your opponent, decide to attack or "take a coffee break", if attack, do so from an advantage and with speed, pull up out of reach and observe results. Rinse and repeat as necessary. Sounds awfully like a "loop" to me.

[Holtzauge]

2 hours ago, =MERCS=JenkemJunkie said:

I can see the logic of that in a different context, but the tempest is really in a league of its own in terms of FM flaws. It flys under its own laws of physics and isn't something players should have to adapt to or crutch on.

Pointing flaws out in here has lead to fixes before, and a fix is already scheduled for the tempest, so its not true to say that its pointless to try to change things.

 

This.

 

And we actually have a very similar problem with one of the Flying Circus flight models where the Albatros D.Va is a bit of the " WW1 Tempest" in that it turns way better than it should. However, the Il-2 Flying Circus crowd are a lot more timid than the WW2 crowd which tends to be more demanding and consequently get more attention. 

[=MERCS=JenkemJunkie]

The squeaky wheel gets the grease, but I'm sure that makes the WWI team happy.

[Avimimus]

Let's try to stay on topic here. Get data, organise it. Flying Circus stuff in another thread. etc.

 

P.S. I personally do tend to the 'see what you can make of it' camp... but I also mainly fly offline, and when I fly online I don't really care about k/d ratios... more 'can I get away with this interesting choice'... kind-of decision making... flying a Mig-3 far too late in the war etc.

[=MERCS=JenkemJunkie]

Stuff like this does tend to be more of a multiplayer problem, I'm not sure if the AI tempest can do the tricks humans do with it.

[ST_Catchov]

22 hours ago, Holtzauge said:

And we actually have a very similar problem with one of the Flying Circus flight models where the Albatros D.Va is a bit of the " WW1 Tempest" in that it turns way better than it should.

 

As an example yes, but it's not the only suspect FC crate.

 

22 hours ago, Holtzauge said:

However, the Il-2 Flying Circus crowd are a lot more timid than the WW2 crowd which tends to be more demanding and consequently get more attention. 

 

Not more timid I think. There have been many robust and impassioned threads on the FM's of various FC kites over the years but when you get the odd vague statement in reply from the devs or nothing at all, it doesn't inspire confidence .... it's hard to battle that and so you tend to let it go. I wish it was not so.

[Ace_Pilto]

On 5/30/2024 at 12:46 AM, Roland_HUNter said:

Are you seriously asking me to give you an example?

No

Things just are what they are. Idk if 1C still does alpha testing like they used to do but that is the place you want to be if you're the stopwatch and clipboard type. I've never been a big expert on how planes are "supposed" to fly. I just take the damn thing, kill people with it and bring it back without bending it too much.

[Panthera]

Apologies for going OT, but the P-51 FM suffers from the same problem, i.e. a way too high a Clmax at low mach numbers. Hence why it's outturning for example the 109s (incl. the 2,000 PS K4) so easily in flat horizontal sustained turns, which it really shouldn't.

 

The laminar flow airfoil designs really don't do very well when it comes to Clmax at the typical maneuvering speeds of propeller driven aircraft (~0.3 mach), it's much better suited for jets which normally maneuver in the region of 0.5-0.8 mach.

 

NACA did comparative flight tests with conventional airfoils to showcase this in the 40s:

 

Edited June 19, 2024 by Panthera

[ACG_Cass]

9 hours ago, Panthera said:

The laminar flow airfoil designs really don't do very well when it comes to Clmax at the typical maneuvering speeds of propeller driven aircraft (~0.3 mach), it's much better suited for jets which normally maneuver in the region of 0.5-0.8 mach.

 

I've seen this claim floated around a lot with regards to the P51 and never really understood what people were refering to. Thank you as I've not seen that report before today.

 

I'm not going to even pretend to know enough about this to explain but the report is looking at the effects of Reynolds number and mach on max lift. With the way Reynolds number changes with altitude/mach number, at high altitudes you'll see this kind of divergence between conventional and laminar flow wings. 0.3 mach at 30,000ft is 150-160mph airspeed.

 

You can see a couple of pages further down a comparison between the P39 & P51 (both have similar power off clmax ~1.34) showing similar clmax/mach plots at lower altitudes.

 

 

 

Absolutely are issues with the P51 FM and it's performance at low speeds but I don't think clmax is the main culprit.

[LukeFF]

Let's keep this topic about the Tempest, please. 

[Roland_HUNter]

We are doing turn time tests for an app in IL-2.
I'm testing the Tempest on autumn, Kuban, 60% of fuel, +11 boost engine, wing loading 180 kg:
With 270 km/h the plane can turn around in 16,36 sec.

That is realistic?

Typhoon on autumn, Kuban, 60% of fuel, +11 boost engine, 4-blades airscrew, wing loading 186 kg:

With 270 km/h the plane can turn around in 18,43sec.

That is realistic?

[Panthera]

On 6/19/2024 at 2:29 PM, ACG_Cass said:

 

I've seen this claim floated around a lot with regards to the P51 and never really understood what people were refering to. Thank you as I've not seen that report before today.

 

I'm not going to even pretend to know enough about this to explain but the report is looking at the effects of Reynolds number and mach on max lift. With the way Reynolds number changes with altitude/mach number, at high altitudes you'll see this kind of divergence between conventional and laminar flow wings. 0.3 mach at 30,000ft is 150-160mph airspeed.

 

You can see a couple of pages further down a comparison between the P39 & P51 (both have similar power off clmax ~1.34) showing similar clmax/mach plots at lower altitudes.

 

 

 

Absolutely are issues with the P51 FM and it's performance at low speeds but I don't think clmax is the main culprit.

 

Not sure why you're comparing the P-51 with the P-39, as they are close at high altitudes too   Look at the difference to the F6F which uses a very similar conventional airfoil design to the Bf-109 (NACA 23xxx and 2R1), and the same as the 190 series. There's a noticable difference, and it's no different at low altitudes.

 

Hence why modern pilots who've flown both the P-51 and 109 all say they're quite far apart when it comes to turning, the 109 always being rated as significantly better, and logically also should be considering the addition of slats (which eventhough only being semi span, contribute to a significant overall lift increase during power on conditions thanks to the inboard wing section already being energized by propwash) and a significant power to weight advantage amongst other things. This is properly represented in for example DCS where the 109 easily outturns the P-51. IL-2 is a big outlier here really.

 

Anyway, I'll leave it at that in this thread, as its OT. 

 

47 minutes ago, Roland_HUNter said:

We are doing turn time tests for an app in IL-2.
I'm testing the Tempest on autumn, Kuban, 60% of fuel, +11 boost engine, wing loading 180 kg:
With 270 km/h the plane can turn around in 16,36 sec.

That is realistic?

Typhoon on autumn, Kuban, 60% of fuel, +11 boost engine, 4-blades airscrew, wing loading 186 kg:

With 270 km/h the plane can turn around in 18,43sec.

That is realistic?

 

I'd expect the Typhoon to turn faster considering the considerably thicker and higher aspect ratio wing using a conventional airfoil design, and not too different power loading. I certainly would never expect a 2+ sec advantage to the Tempest.

Edited June 23, 2024 by Panthera

[CountZero]

10 hours ago, Roland_HUNter said:

We are doing turn time tests for an app in IL-2.
I'm testing the Tempest on autumn, Kuban, 60% of fuel, +11 boost engine, wing loading 180 kg:
With 270 km/h the plane can turn around in 16,36 sec.

That is realistic?

Typhoon on autumn, Kuban, 60% of fuel, +11 boost engine, 4-blades airscrew, wing loading 186 kg:

With 270 km/h the plane can turn around in 18,43sec.

That is realistic?

any videos or just trust me bro ?

 

out of interest what times you get doing same tests for other fighters, or 12s for Spit9 , 14s for 109F4 , 16s for 190 ? or for them its all like in specs 20+s

[Roland_HUNter]

1 hour ago, CountZero said:

any videos or just trust me bro ?

 

out of interest what times you get doing same tests for other fighters, or 12s for Spit9 , 14s for 109F4 , 16s for 190 ? or for them its all like in specs 20+s

The turn time will be shown in this app, when it's done.

I tried to to reconstruct again, I got a "little" bit "worse" turn times:

 

 

[ACG_Cass]

On 6/23/2024 at 1:05 AM, Panthera said:

Not sure why you're comparing the P-51 with the P-39, as they are close at high altitudes too

 

Not according to the chart you provides. The P39 has a conventional airfoil, the P51 a low drag one.

 

On 6/19/2024 at 4:11 AM, Panthera said:

The laminar flow airfoil designs really don't do very well when it comes to Clmax at the typical maneuvering speeds of propeller driven aircraft (~0.3 mach), it's much better suited for jets which normally maneuver in the region of 0.5-0.8 mach.

 

You stated laminar flow wings do not produce their clmax at typical maneuvering speeds, yet the P51 and P39 show correlation at lower altitudes. 0.3 mach at 30,000ft is below normal maneuvering airspeed for a WW2 fighter.

 

You stated the clmax of the P51 at low mach was too high. The clmax of the P51 in IL2 power off, low mach at sea level (the most important one) is ~1.34. This aligns with the huge amounts of irl data on the aircraft.

On 6/19/2024 at 4:11 AM, Panthera said:

a way too high a Clmax at low mach numbers

 

I believe on topic as the Tempest has a low drag airfoil so key to clarify that isn't the issue

 

Not so on topic...

 

On 6/23/2024 at 1:05 AM, Panthera said:

Hence why modern pilots who've flown both the P-51 and 109 all say they're quite far apart when it comes to turning, the 109 always being rated as significantly better, and logically also should be considering the addition of slats (which eventhough only being semi span, contribute to a significant overall lift increase during power on conditions thanks to the inboard wing section already being energized by propwash) and a significant power to weight advantage amongst other things. This is properly represented in for example DCS where the 109 easily outturns the P-51. IL-2 is a big outlier here really.

 

It is difficult to take modern pilots testimonial as a comparison as "turn" can mean so many things. The 109 should feel like it out turns the P51 <300mph if you aren't pushing up to stall as it has lighter stick forces at those speeds. The P51 is actually quite heavy on the stick, however, those forces stay the same until higher speed so above 300mph, when most other aircraft start locking up, it will still be responsive.

 

F̶r̶o̶m̶ a̶n̶ a̶c̶t̶u̶a̶l̶ n̶u̶m̶b̶e̶r̶s̶ p̶e̶r̶s̶p̶e̶c̶t̶i̶v̶e̶,̶ t̶h̶e̶ P̶5̶1̶ s̶h̶o̶u̶l̶d̶ j̶u̶s̶t̶ o̶u̶t̶ t̶u̶r̶n̶ t̶h̶e̶ 1̶0̶9̶ i̶n̶ i̶n̶s̶t̶a̶n̶t̶a̶n̶e̶o̶u̶s̶ t̶u̶r̶n̶s̶ p̶r̶o̶v̶i̶d̶i̶n̶g̶ t̶h̶e̶y̶ a̶r̶e̶ n̶o̶t̶ s̶t̶i̶c̶k̶ f̶o̶r̶c̶e̶/̶p̶i̶l̶o̶t̶ g̶ l̶i̶m̶i̶t̶e̶d̶.̶ A̶l̶t̶h̶o̶u̶g̶h̶ t̶h̶e̶ 1̶0̶9̶ h̶a̶s̶ a̶ h̶i̶g̶h̶e̶r̶ c̶l̶m̶a̶x̶ (̶~̶1̶.̶4̶0̶)̶,̶ i̶t̶ h̶a̶s̶ a̶ h̶i̶g̶h̶e̶r̶ w̶i̶n̶g̶ l̶o̶a̶d̶i̶n̶g̶ m̶e̶a̶n̶i̶n̶g̶ w̶i̶t̶h̶ b̶o̶t̶h̶ a̶i̶r̶c̶r̶a̶f̶t̶ a̶t̶ 5̶0̶%̶ f̶u̶e̶l̶ t̶h̶e̶ P̶5̶1̶ h̶a̶s̶ a̶ l̶o̶w̶e̶r̶ s̶t̶a̶l̶l̶ s̶p̶e̶e̶d̶.̶  Corrected below. The 109 has a very slight edge on stall speed but the two are close enough where the dynamics of an engagement would mean it wouldn't be noticeable above other factors. The point still stands around the higher lift but higher wingloading.

 

P51D

Weight 50%: 4212kg

Wing Area: 22.3m²

Wing Loading: 189kg/m²

Clmax: 1.34

Stall: 171kph

 

Bf109 G14

Weight 50%: 3212kg

Wing Area: 16.1m²

Wing Loading: 193kg/m²

Clmax: 1.4

Stall: 169kph

 

The area the P51 stands out in is it's speed retention during maneuvers. I think the likely issue is too little drag at higher AoA. The power to weight ratio of the 109 is significantly higher meaning it should start winning out at lower speeds where sustained turn comes into play.

Edited June 26, 2024 by ACG_Cass

[the_emperor]

55 minutes ago, ACG_Cass said:

Bf109 G14

Weight 50%: 3413kg

Wing Area: 16.1m²

Wing Loading: 212kg/m²

Clmax: 1.4

Stall: 177kph

 

Small correction:

Bf109 G14

Weight fuel 400l (100%): 3250kg

Weight fuel 200l : 3102kg

Wing Area: 16.1m²

Clmax: 1.4 (does this take slats into account at low speed manoeuvring)?

Wing Loading: 201/192 kg/m²

 

[Aurora_Stealth]

2 hours ago, ACG_Cass said:

 

Not according to the chart you provides. The P39 has a conventional airfoil, the P51 a low drag one.

 

 

You stated laminar flow wings do not produce their clmax at typical maneuvering speeds, yet the P51 and P39 show correlation at lower altitudes. 0.3 mach at 30,000ft is below normal maneuvering airspeed for a WW2 fighter.

 

You stated the clmax of the P51 at low mach was too high. The clmax of the P51 in IL2 power off, low mach at sea level (the most important one) is ~1.34. This aligns with the huge amounts of irl data on the aircraft.

 

I believe on topic as the Tempest has a low drag airfoil so key to clarify that isn't the issue

 

Not so on topic...

 

 

It is difficult to take modern pilots testimonial as a comparison as "turn" can mean so many things. The 109 should feel like it out turns the P51 <300mph if you aren't pushing up to stall as it has lighter stick forces at those speeds. The P51 is actually quite heavy on the stick, however, those forces stay the same until higher speed so above 300mph, when most other aircraft start locking up, it will still be responsive.

 

From an actual numbers perspective, the P51 should just out turn the 109 in instantaneous turns providing they are not stick force/pilot g limited. Although the 109 has a higher clmax (~1.40), it has a higher wing loading meaning with both aircraft at 50% fuel the P51 has a lower stall speed. The two are close enough where the dynamics of an engagement would mean more.

 

P51D

Weight 50%: 4212kg

Wing Area: 22.3m²

Wing Loading: 189kg/m²

Clmax: 1.34

Stall: 171kph

 

Bf109 G14

Weight 50%: 3413kg

Wing Area: 16.1m²

Wing Loading: 212kg/m²

Clmax: 1.4

Stall: 177kph

 

The area the P51 stands out in is it's speed retention during maneuvers. I think the likely issue is too little drag at higher AoA. The power to weight ratio of the 109 is significantly higher meaning it should start winning out at lower speeds where sustained turn comes into play.

 

Broadly agree with your points, I think the CLmax for the Bf 109 has been chewed over in previous threads and the developers reviewed the flight models for it a while back. The limitations of the game engine may be playing a part on more sophisticated drag effects, anyway let's please focus on the topic in hand. The flight model of the Tempest V is what's in question here. Few people are convinced of the Tempest's current "capability" and the fact that its possible to pull off the wings at around medium-ish speeds implies there is excessive authority allowable and that's because the aircraft's lift capacity (CLmax) is well beyond its actual numbers - the fact it takes so long to reach an accelerated stall at relatively low speed is unmistakeable for an aircraft of this size, weight and aerofoil.

 

Apart from some of the numbers being a little out regards to the Bf 109 as @the_emperor mentioned, one thing in principle in your post is a little misleading here regards to the stall speeds you mention.

 

I just want to clarify this, as it applies in principle to all aircraft using high speed aerofoils such as the P-51, Tempest V.

 

Yes, if these were flown in straight and level flight then your quoted lower stall speed would imply an advantage but its not in practice when you factor in the accelerated stall and the behaviour of "semi-laminar" flow wings (credit to Calum Douglas for his neat description) when manoeuvring at significant AOA's.

 

In practice you'd need to fly (and every modern day pilot will tell you this who has compared these with other warbirds) that there must be a greater cushion of speed kept above the stall if you're doing hard manoeuvring with these types of aerofoil. They are extremely unforgiving if you get into an accelerated stall; often with a resulting harsh spin and you cannot risk losing control like this - its fatal. The speed tapers off deceptively quickly at high AOA's due to the characteristics of these aerofoils. Energy retention once you get to high speed when using low AOA's is great but as soon as you start disrupting this flow significantly with high AOA's then you bleed speed faster than other aerofoils... this can lull you into an aggressive accelerated stall... you're not going to have time to watch every knot of speed fall off in combat and unless you have a death wish or a very sloppy opponent (not uncommon with Luftwaffe by 1944) you are not going to encourage going up to this stall speed as the Mustang (for example) spins at something close to 210 degrees per second. Similar issues will exist with the Tempest because it also uses a 'semi-laminar' / high speed aerofoil; although there is more surface area which may help to some degree.

 

To give another drawback with these aerofoils is yeah I agree the stick forces... when doing loops at airshows as performed by the famous 'Three Horsemen' P-51 team they had to be performed by accurately adjusting the trim throughout coordinated loops to compensate for the less than ideal trim changes on the aircraft. That may work in a wide manoeuvre that is practiced but its going to be next to impossible in short aggressive / snap manoeuvres like what the Bf 109 can perform... this is problematic if you are co-energy with it which is why you really must keep the speed advantage to win against it in a fight like this.

 

In short, the stall speed is not to be taken at face value with these semi-laminar flow aerofoils for manoeuvring or combat purposes; just like with the Tempest V. It's not a practical reference when pulling G's; the controls become extremely sluggish and unresponsive once you lose speed and while maintaining significant AOA's and at that point is just asking for the aircraft to become paralysed in a stall - neither the P-51 or Tempest could be considered particularly "light" as fighters and that's only touching on the changing stick force and trim changes which is assumed to be managed by a pilot in a dogfight.

Edited June 26, 2024 by Aurora_Stealth

[ACG_Cass]

9 hours ago, the_emperor said:

Small correction:

Bf109 G14

Weight fuel 400l (100%): 3250kg

Weight fuel 200l : 3102kg

Wing Area: 16.1m²

Clmax: 1.4 (does this take slats into account at low speed manoeuvring)?

Wing Loading: 201/192 kg/m²

Thank you! Corrected. Kept rechecking as I remember them being pretty much the same stall speed last time I calculated. I was taking the maximum load for the 109.

 

8 hours ago, Aurora_Stealth said:

Apart from some of the numbers being a little out regards to the Bf 109 as @the_emperor mentioned, one thing in principle in your post is a little misleading here regards to the stall speeds you mention.

 

I completely agree but wanted to make it clear that the actual maximum lift performance of the P51 is fine as it is and that low drag wings do not make their maximum lift at higher mach.

 

8 hours ago, Aurora_Stealth said:

To give another drawback with these aerofoils is yeah I agree the stick forces...

 

This principle isn't necessarily true for the Tempest FYI m. It had very light stickforces.

 

8 hours ago, Aurora_Stealth said:

In practice you'd need to fly (and every modern day pilot will tell you this who has compared these with other warbirds) that there must be a greater cushion of speed kept above the stall if you're doing hard manoeuvring with these types of aerofoil. They are extremely unforgiving if you get into an accelerated stall; often with a resulting harsh spin and you cannot risk losing control like this - its fatal. The speed tapers off deceptively quickly at high AOA's due to the characteristics of these aerofoils. Energy retention once you get to high speed when using low AOA's is great but as soon as you start disrupting this flow significantly with high AOA's then you bleed speed faster than other aerofoils... this can lull you into an aggressive accelerated stall...

Do you have any data/reports on this? Not questioning but obviously need to find a way to quantify it.

 

I have cl/mach/drag charts for the P51/P47/Tempest but its difficult to draw too much from them as they don't constantly go above 1.0 cl where the AoA becomes a factor.

 

P47

 

Tempest

 

P51

[Panthera]

16 hours ago, ACG_Cass said:

 

Not according to the chart you provides. The P39 has a conventional airfoil, the P51 a low drag one.

 

 

You stated laminar flow wings do not produce their clmax at typical maneuvering speeds, yet the P51 and P39 show correlation at lower altitudes. 0.3 mach at 30,000ft is below normal maneuvering airspeed for a WW2 fighter.

 

You stated the clmax of the P51 at low mach was too high. The clmax of the P51 in IL2 power off, low mach at sea level (the most important one) is ~1.34. This aligns with the huge amounts of irl data on the aircraft.

 

I believe on topic as the Tempest has a low drag airfoil so key to clarify that isn't the issue

 

Not so on topic...

 

 

It is difficult to take modern pilots testimonial as a comparison as "turn" can mean so many things. The 109 should feel like it out turns the P51 <300mph if you aren't pushing up to stall as it has lighter stick forces at those speeds. The P51 is actually quite heavy on the stick, however, those forces stay the same until higher speed so above 300mph, when most other aircraft start locking up, it will still be responsive.

 

F̶r̶o̶m̶ a̶n̶ a̶c̶t̶u̶a̶l̶ n̶u̶m̶b̶e̶r̶s̶ p̶e̶r̶s̶p̶e̶c̶t̶i̶v̶e̶,̶ t̶h̶e̶ P̶5̶1̶ s̶h̶o̶u̶l̶d̶ j̶u̶s̶t̶ o̶u̶t̶ t̶u̶r̶n̶ t̶h̶e̶ 1̶0̶9̶ i̶n̶ i̶n̶s̶t̶a̶n̶t̶a̶n̶e̶o̶u̶s̶ t̶u̶r̶n̶s̶ p̶r̶o̶v̶i̶d̶i̶n̶g̶ t̶h̶e̶y̶ a̶r̶e̶ n̶o̶t̶ s̶t̶i̶c̶k̶ f̶o̶r̶c̶e̶/̶p̶i̶l̶o̶t̶ g̶ l̶i̶m̶i̶t̶e̶d̶.̶ A̶l̶t̶h̶o̶u̶g̶h̶ t̶h̶e̶ 1̶0̶9̶ h̶a̶s̶ a̶ h̶i̶g̶h̶e̶r̶ c̶l̶m̶a̶x̶ (̶~̶1̶.̶4̶0̶)̶,̶ i̶t̶ h̶a̶s̶ a̶ h̶i̶g̶h̶e̶r̶ w̶i̶n̶g̶ l̶o̶a̶d̶i̶n̶g̶ m̶e̶a̶n̶i̶n̶g̶ w̶i̶t̶h̶ b̶o̶t̶h̶ a̶i̶r̶c̶r̶a̶f̶t̶ a̶t̶ 5̶0̶%̶ f̶u̶e̶l̶ t̶h̶e̶ P̶5̶1̶ h̶a̶s̶ a̶ l̶o̶w̶e̶r̶ s̶t̶a̶l̶l̶ s̶p̶e̶e̶d̶.̶  Corrected below. The 109 has a very slight edge on stall speed but the two are close enough where the dynamics of an engagement would mean it wouldn't be noticeable above other factors. The point still stands around the higher lift but higher wingloading.

 

P51D

Weight 50%: 4212kg

Wing Area: 22.3m²

Wing Loading: 189kg/m²

Clmax: 1.34

Stall: 171kph

 

Bf109 G14

Weight 50%: 3212kg

Wing Area: 16.1m²

Wing Loading: 193kg/m²

Clmax: 1.4

Stall: 169kph

 

The area the P51 stands out in is it's speed retention during maneuvers. I think the likely issue is too little drag at higher AoA. The power to weight ratio of the 109 is significantly higher meaning it should start winning out at lower speeds where sustained turn comes into play.

 

 

No, the P-39 uses a symmetrical airfoil design for most of its wing (NACA 00XX series), with only the tips using a conventional assym. design, hence the relatively low Clmax on that aircraft. The F6F on other hand, just like the Bf-109 and Fw-190, uses a conventional assymetrical airfoil design (NACA 23xxx) for the entire wingspan. Therefore it is naturally the F6F curves you should be comparing with, and the difference is signifcant.

 

As for the Clmax in IL2, I can only once again state that it's off for the 109. To put it into perspective the windtunnel testing of 109V24, which featured a cropped wing (thus lower AR) and no slats, resulted in a Clmax of ~1.44-1.48.  

 

That aside it is infact during sustained turns that the 109 esp. cannot compete with the P-51 in IL2, whilst realistically the MW50 equipped 109's should be very easily out rating the P-51 here, irrespective of wether we're talking the a light Mustang using 67 or 75" Hg boost -> which is exactly how it is in DCS for example, where no amount of fuel state difference is going to have the P-51D able to match the 109K4 in sustained rate. The difference in powerloading and induced drag is simply too big. 

 

Now you could be right about the P-51 in IL2 suffering from too little drag at AoA, that is definitely a possibility, either that or the 109 in conjunction with its too low Clmax is suffering from too much drag at AoA as well, again also possible.

 

[ACG_Cass]

6 hours ago, Panthera said:

No, the P-39 uses a symmetrical airfoil design for most of its wing (NACA 00XX series), with only the tips using a conventional assym. design, hence the relatively low Clmax on that aircraft. The F6F on other hand, just like the Bf-109 and Fw-190, uses a conventional assymetrical airfoil design (NACA 23xxx) for the entire wingspan. Therefore it is naturally the F6F curves you should be comparing with, and the difference is signifcant.

 

As for the Clmax in IL2, I can only once again state that it's off for the 109. To put it into perspective the windtunnel testing of 109V24, which featured a cropped wing (thus lower AR) and no slats, resulted in a Clmax of ~1.44-1.48.  

 

 

I think we're straying from what I was trying to say. 1.4 for the 109 comes from a corrected stall speed test the RAE conducted, which they did for the 190 and F6F that has given us their clmax. Certainly might not have been perfect so it could very well be 1.44-1.48 but I'm not discussing actual clmax numbers.

 

On 6/19/2024 at 4:11 AM, Panthera said:

The laminar flow airfoil designs really don't do very well when it comes to Clmax at the typical maneuvering speeds of propeller driven aircraft

This is the part that I wanted to make clear is incorrect from an actual aerofoil performance perspective unless at very high altitudes where critical mach comes into play.

 

There are other factors at play as @Aurora_Stealth has pointed out that mean getting maximum performance is challenging that also potentially need to modelled but from a flight model design perspective, the clmax is not the issue.

[Mandoble]

What about pilots testimonies? Was the Typhoon turning better than the Tempest (which is, actually, my understanding)?