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Another look at turn times

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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.  ;)

 

What I’m hoping for is a response on the observation I made in the FM report that the problem with the Me-109’s turn times is most likely not a propeller efficiency problem but something else, most likely a drag at high aoa problem meaning this can be fixed even if the community does not produce any VDM propeller data.

 

And regarding the C++ model: This can be verified like any complex model: You throw scenarios at it where you already have historical data you trust and monitor the output from the model: If the output conforms to the data you have you can as you notch up conformance points build a trust that it can also predict behaviour outside the known data points. But you can do the same with pen and paper and I’m merely pointing out an inconsistency and as you say the developers have already confirmed that there is a problem with the Me-109 turn times so I don’t think they are questioning my results but if they have any questions or want me to run some numbers for them I will of course do that.

 

However, that is not the reason for my report: The reason for the report is to point out that the problem is probably not related to the propeller modelling but to the L/D drag modelling at higher aoa and consequently it should be possible to fix the problem without the missing specific VDM propeller data they asked the community for. I’m guessing that the request for the VDM data stems from an early analysis or an observation that they have data for other planes but are missing it for the Me-109 so it makes perfect sense then as a first guess to suspect that it is propeller issue. The other explanation would be that the missing VDM is used as an excuse not to fix the problem but so far I have seen no such tendency since the developers have a track record of acting on community input which is why I did the report.

 

So now I’m looking forward to the response and will of course (unless the developers tell me things in confidence) keep the community updated on where this goes. :)

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I rarely fly LW fighters, but as little as my anecdotal experience can add anything to this topic, I do find that 109 wastes a huge amount of E in high AOA turns, in comparison to most of the red fighters. I just feel like the slats act as airbrakes sometimes.

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8 hours ago, JaffaCake said:

I rarely fly LW fighters, but as little as my anecdotal experience can add anything to this topic, I do find that 109 wastes a huge amount of E in high AOA turns, in comparison to most of the red fighters. I just feel like the slats act as airbrakes sometimes.

 

When it comes to the drag at best turn speed you are flying basically at Clmax and the overwhelming part of the drag is due to the induced drag and the added slat drag (which affects the wing profile drag) is much much smaller. Frankly, I think the Me-109 turn rate we have today stems from some early tuning of the FM. If one remembers that the Me-109 before the roll tuning was quite good and you could roll pretty well even at higher speeds it's no leap of logic IMHO that it could be the same with the L/D: A certain tuning was selected in the initial modeling and just like with the roll rate the turn modelling simply needs some TLC. ;)

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Yes, like Holtzauge says the parasitic drag (that's everything besides induced drag) added by the slats would, considering the shape and size of the slat & opening (not to mention the  position its in relative to the airstream when opened),  be 1. incredibly small and 2. down almost purely to added surface area. Now then when we consider how small an amount of extra surface area is added by the opening of a LE slat as compared to the corresponding increase in wing area that would be needed to achieve a similar L/W ratio that slats provide, then it becomes clear why LE slats became such a popular feature in fighter aircraft design, esp. post war, despite the obvious increase in cost & complexity that comes with it.

 

 

 

 

 

 

Edited by Panthera

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I am under no impression that slats are the reason for the drag. It is just the slats indicate high AOA situation, which in 109 results in rapid loss of E. So while they are not airbrakes (my failed attempt at sarcasm), they are an indication that you are dumping your E down the drain with the current FM.

Edited by JaffaCake

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7 hours ago, JaffaCake said:

I am under no impression that slats are the reason for the drag. It is just the slats indicate high AOA situation, which in 109 results in rapid loss of E. So while they are not airbrakes (my failed attempt at sarcasm), they are an indication that you are dumping your E down the drain with the current FM.

 

Well high AOA results in rapid loss of E for all aircraft, not just the 109. The problem here is that the way the 109 is currently modeled in-game is that it is slowing down faster and "dumping E  down the drain" faster than it should when you pull that high AOA.

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Also that the critical AoA for the 109s appears to be a degree or so higher than for most allied types - except the La5s for some reason. If you are turning at close to critical AoA presumably the extra drag of 1 degree more AoA would be fairly significant?

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Well actually the induced drag is more coupled to the lift you take out of the wing and the wing planform than the actual aoa: The critical aoa OTOH depends on how the wing is set up in relation to the datum line and also the wing camber plays in but basically the drag will be proportional to the square of the Cl and dependent on the oswald factor e at that Cl.

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7 hours ago, Holtzauge said:

Well actually the induced drag is more coupled to the lift you take out of the wing and the wing planform than the actual aoa: The critical aoa OTOH depends on how the wing is set up in relation to the datum line and also the wing camber plays in but basically the drag will be proportional to the square of the Cl and dependent on the oswald factor e at that Cl.

 

It is complicated - I get it. :)

 

But the 109s also have higher CLmax in game than the allied designs. At max operational weight:

 

G-2 1.40    squared = 1.96

Spitfire V 1.33  squared = 1.77

 

Ie G-2 CLmax squared is 11% higher than for Spitfire. So other things being equal (and I know that they are not) if both are turning at CLmax the G-2 induced drag will be 11% higher than the Spitfire's - so it will feel like it is "losing energy" faster.

 

I know it is all terribly complicated - I am simply asking if it is possible that the "loses energy faster" point that has been raised could be a natural and correct result of the higher achievable AoA and CLmax when turning in a 109, rather than a mistake in the FM, which some people seem to be assuming.

 

 

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14 hours ago, unreasonable said:

 

It is complicated - I get it. :)

 

But the 109s also have higher CLmax in game than the allied designs. At max operational weight:

 

G-2 1.40    squared = 1.96

Spitfire V 1.33  squared = 1.77

 

Ie G-2 CLmax squared is 11% higher than for Spitfire. So other things being equal (and I know that they are not) if both are turning at CLmax the G-2 induced drag will be 11% higher than the Spitfire's - so it will feel like it is "losing energy" faster.

 

I know it is all terribly complicated - I am simply asking if it is possible that the "loses energy faster" point that has been raised could be a natural and correct result of the higher achievable AoA and CLmax when turning in a 109, rather than a mistake in the FM, which some people seem to be assuming.

 

 

 

Very valid points but the thing is that those squared numbers go into my simulations as well and just like you point out the Spitfire does come off better in that comparison but then so did it IRL as well and so it does also in my simulations.

 

In addition to the Russian turn rate figures I actually have some German numbers as well and both the German and Russian stated numbers for the Friedrich and Gustav are lower for a 360-degree turn than what we have in-game today.

 

But are we really questioning the need to fix the 109F/G turn rate? I mean I'm not alone in this: The developers themselves have acknowledged the problem and to me it's now more a discussion on what needs to be fixed in the FM not if there is or isn't a problem?

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19 hours ago, RoflSeal said:

Could a potential problem be also that slats are deploying at too low an AoA?

 

Well it's some time since I tested this in-game but IIRC then they deployed pretty much as they should. IRL they should start to come out at a Cl=0.8 and be fully deployed at Cl=1.2 but as both  I and Panthera have pointed out, the slats in themselves don't add much drag compared to the induced drag and in fact they may even lower it since when you start going to higher aoa the flow starts to separate and that causes a lot more drag than the opening of a slat.

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I was simply picking up on a specific comment earlier (too tired to find it ATM) about how the 109s "seem to lose energy" in turns or a similar formulation and thinking about that particular perception. Given that it is possible to generate a higher AoA and achieve a higher CLmax in a 109 than a Spitfire, I can imagine, given your explanation of how induced drag is generated, that if you really push them to the limit you will feel the increase in drag more in terms of deceleration compared to before entering the turn - not so much the turn time itself.

 

As usual a lot of different things can get mixed into these discussions -   I am not questioning that there is a recognized issue with the measured best turn rates.

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OK, then I see what you mean. I was actually also posting in response to that comment since the loss of energy is connected to the turn rate issue since when this is fixed then the Me-109 will not loose as much energy when manouvering because that will be a consequence of fixing the turn rate issue. But like you point out: the 109 will for sure lose more energy than the Spitfire when turning tight and I don't expect this to change after the fix either and I predict those who try that trick after fix will be sorely disappointed. ;)

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Yes - a couple of seconds off the turn time and some people will be saying that this is like a whole new game and others will deny that anything has actually changed. :)

 

Thanks for your patience - always a lot to learn in this sub-forum.

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On 6/3/2018 at 7:37 PM, unreasonable said:

Also that the critical AoA for the 109s appears to be a degree or so higher than for most allied types - except the La5s for some reason. If you are turning at close to critical AoA presumably the extra drag of 1 degree more AoA would be fairly significant?

 

The extra drag you get for that extra AoA is tied directly to the extra lift you gain from it. In short it's entirely induced drag. How so?  Because non turbulent flow is simply maintained for longer whilst wing area remains unchanged. Had the slats not been there you would get the dramatic increase in drag for that extra AoA with complete boundary layer seperation, also known as a stall. 

 

Also that the La-5 has the same extra deg of usable AoA as the 109 shouldn't come as a surprise as it also features slats :)

 

Edited by Panthera
erased obvious incorrection

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52 minutes ago, Holtzauge said:

OK, then I see what you mean. I was actually also posting in response to that comment since the loss of energy is connected to the turn rate issue since when this is fixed then the Me-109 will not loose as much energy when manouvering because that will be a consequence of fixing the turn rate issue. But like you point out: the 109 will for sure lose more energy than the Spitfire when turning tight and I don't expect this to change after the fix either and I predict those who try that trick after fix will be sorely disappointed. ;)

 

Indeed the Spitfire's advantage in wing loading is simply too great, thus a 109 pilot shouldnt ever expect being able to turn tighter. Could a 109 keep up for a while in a sustained turn? Maybe, depends on the power available, but overall I'd advise any 109 pilot to use the vertical when fighting spits. 

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8 hours ago, Panthera said:

 

<snip>

 

Also that the La-5 has the same extra deg of usable AoA as the 109 shouldn't come as a surprise as it also features slats :)

 

 

That part I did not know - the La being one of several BoX planes I have never got round to exploring. It is indeed a sensible explanation: although it is interesting that the La5 has a critical AoA at 22.7 over 4 degrees higher than the LaGG3 with the most similar wing without slats at 18.0, the CLmax is not very different: 1.275 vs 1.237, only a 3% improvement.   Makes you wonder what the La's CLmax would be with the slats wired shut. 

 

As always, lots going on, defying simple explanations: at least by me. :)  

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22 hours ago, Panthera said:

 

Indeed the Spitfire's advantage in wing loading is simply too great, thus a 109 pilot shouldnt ever expect being able to turn tighter. Could a 109 keep up for a while in a sustained turn? Maybe, depends on the power available, but overall I'd advise any 109 pilot to use the vertical when fighting spits. 

 

Yes, I agree with that: Even though the Me-109 is not quite as good as the Spitfire in a turn, its no slouch and it should get even better when we get the fix in-game. ;)

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Not sure I follow?

 

The stats for the new planes are available, but how they compare with Holtzauge's C++ simulation I'm not sure besides from the La-5FN which he did post some graphs for.

 

 

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17 hours ago, Panthera said:

Not sure I follow?

 

The stats for the new planes are available, but how they compare with Holtzauge's C++ simulation I'm not sure besides from the La-5FN which he did post some graphs for.

 

 

 

I also added the P39L to the table now: Looks like this is more conservatively modeled, just like the German fighters.

 

 

Turn performance chart with P39L added.gif

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10 minutes ago, MK_RED13 said:

G2 and G6 ? Is it joke?

Looks like the devs still missing some data.

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1 hour ago, L3Pl4K said:

Looks like the devs still missing some data.

 

I think they commented that they were lacking the official prop efficiency figures, but in that case they shouldn't be able to hit the historical speed & climbs rates  of the aircraft without having to use incorrect drag data.

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7 minutes ago, Panthera said:

 

I think they commented that they were lacking the official prop efficiency figures, but in that case they shouldn't be able to hit the historical speed & climbs rates  of the aircraft without having to use incorrect drag data.

 

Exactly and that is why I made the FM report on the Me-109 turn rate because it does not add up: If it is the prop efficiency then that should hurt the climb rates  as well but it doesn't so it look more like a L/D rate issue as low speeds. Unfortunately I have had no response to my FM report but for the time being I'm taking a positive attitude to that and assuming it's because they have not yet had the time to look at it because of the 3.001 release.

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Yeah, let's hope they respond soon and find the time to fix it within the next couple of months.

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I've updated the original table in the first post. No data has changed, but a couple of new planes are included.

 

My primary issue, the Yak-7 does not make sense at all. By now it looks like there is a different sort of aerodynamics at work as soon as an aircraft is powered by a Klimov. I have included it twice because the devs gave a range of 19-20s for the turn time. It should be noted that this figure is already considerably worse than some data available for the plane, so hats off for not blindly following implausible figures to the very end. I still think it is too optimistic, it definitely is when compared to other aircraft.

 

Some of this is down to an apparent change in FM modelling philosophy, resulting in generally higher efficiencies with newer planes. I just hope they find the time to update the older FM's accordingly.

 

Good news is the A-20 at combat power without bombs has no problem out-turning any German fighter in game at sea level in a sustained turning contest.

 

 

bla002.jpg

Edited by JtD
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1 hour ago, JtD said:

Good news is the A-20 at combat power without bombs has no problem out-turning any German fighter in game at sea level in a sustained turning contest.

 

Damn, didn't know it was that bad, that's crazy :o:

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The A-20 was a great performer. Turning performance is what could be expected, to some extent. If you look at the significant parameters like power-loading, span-loading and wing-loading, it isn't worse than some single engined fighters. Some of the earlier 109's should be superior, but they appear to suffer from the already mentioned earlier and more conservative FM philosophy - imho the key issue.

 

The A-20 isn't anywhere near single engined fighters in terms of permissible load factors, agility or handling.

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2 hours ago, JtD said:

The A-20 was a great performer. Turning performance is what could be expected, to some extent. If you look at the significant parameters like power-loading, span-loading and wing-loading, it isn't worse than some single engined fighters. Some of the earlier 109's should be superior, but they appear to suffer from the already mentioned earlier and more conservative FM philosophy - imho the key issue.

 

The A-20 isn't anywhere near single engined fighters in terms of permissible load factors, agility or handling.

 

I dunno seems a bit far fetched if it can outturn the German single seaters, esp. sustained :D

 

Just looking at the basic numbers ~9200 kg, 43 m^2 and 3200 hp, I can't see it coming close to the single seaters. Running the math the difference is quite stark infact. The Bf-110 looks a lot more favorable though, but still not superior to the single seaters.

Edited by Panthera

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If you're being out turned by an A-20 while flying a 109, you've done something terribly stupid and deserve to be shot down.

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1 hour ago, LukeFF said:

If you're being out turned by an A-20 while flying a 109, you've done something terribly stupid and deserve to be shot down.

 

You really have a beautiful way communicating with words LukeFF, always so positive and non judgemental :happy: 

 

 

_______________________________________

 

 

Okay just tried out the A-20 ingame, and oh my word does it turn! Infact I was able to outturn an ace level Spitfire, something I either struggle or simply can't do in most of the single seaters :o: 

 

Something very weird is going on with this FM, the A-20 most certainly retains energy & turns way better than it should, and the 24.5 sec listed for it is nowhere close to what this thing can actually achieve ingame.

 

Curiously they seemed to have gotten the Bf-110G modelled completely differently, despite it in general having a lower wing, power & span loading than the A-20, on top of leading edge slats. Thus in all honesty it should turn better than the A-20, but ingame it doesn't even come close.

 

IL-2's flight models are really confusing me right now :wacko:

Edited by Panthera

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7 hours ago, JtD said:

My primary issue, the Yak-7 does not make sense at all. By now it looks like there is a different sort of aerodynamics at work as soon as an aircraft is powered by a Klimov. I have included it twice because the devs gave a range of 19-20s for the turn time. It should be noted that this figure is already considerably worse than some data available for the plane, so hats off for not blindly following implausible figures to the very end. I still think it is too optimistic, it definitely is when compared to other aircraft.

 

Some of this is down to an apparent change in FM modelling philosophy, resulting in generally higher efficiencies with newer planes. I just hope they find the time to update the older FM's accordingly.

Han in Developer Diary 186

"The end of January draws near and we're finishing the BoK development. The new functionality of the coming version 3.001 is being actively tested and debugged, our volunteer beta tester team helps us in this task greatly. This development stage is hard, but it consists of routine work mostly, not very exciting to tell about. However, there is a development which might be interesting for you to know. Andrey =AnPetrovich= Solomykin finished the Yak-7b series 36 flight model but, being the lead engineer, he couldn't just 'make a new plane'. During this work, he implemented many new features which in time may be applied to other aircraft. In addition, while we have a common flight modeling accuracy standard, this time some characteristics were modeled with higher fidelity. Here's the list of Yak-7b FM features:
 
1. Maximum horizontal speed matches the reference data at all altitudes with 1% difference margin (less than 5 km/h).
2. Climb time matches the reference data with 4% difference margin (less than 8 seconds difference lower than 6000 m and less than 34 seconds at higher altitudes).
3. Turn time matches the reference data with 0.5 seconds difference margin.
4. Takeoff and landing speeds with or without flaps match the reference data with 2-3 km/h difference margin (takeoff run accuracy is 10-20 m).
5. Inertial model is congruent with the reference data for all load variants including fuel and ammo mass.
6. Shock absorbers and tire load are congruent with the reference data in all drop tests.
7. New canopy functionality:
7.1 Canopy opening or closing delay after the player input has been corrected.
7.2 It is impossible to open or close the canopy at speeds higher than 600 km/h.
7.3 Canopy damage model and wind sound corrected.
7.4 Moving canopy recoils when it hits the limit.
7.5 Player can repeat the canopy move command if canopy releases from the lock on its own and didn't lock at the opposite lock.
7.6 If a pilot finds himself in an unlucky flip over situation on the ground, it may be impossible to open the canopy.
8. New flaps functionality:
8.1 Flaps pneumatic valve can be set to the neutral position instead of retracting position, making the flaps retract by air flow pressure instead of a sharp retracement.
8.2 An incorrect flaps behavior, while pushed back by the air flow pressure, has been addressed.
9. Pneumatic valves in the cockpit are being turned in an anthropomorphically realistic way since a human hand can't turn something 360 degrees without pauses.
10. Constant speed governor wheel has been slowed down realistically (synchronized with a virtual axis while controlling it from keyboard).
11. Propeller pitch automatically lowers during landing if the automatic pitch control is selected in difficulty settings.
12. Oil overpressure results in an oil leak.
13. Oil and water radiator scoops can be lost due to combat damage.
14. The airframe structural fatigue and combat damage dependencies on the G load have been adjusted.
15. Fuel pressure indicator shows realistic data while the engine cylinders are being primed with fuel during the engine start.
16. Force Feedback effects were adjusted for higher flight speeds.
17. Oil injector functions correctly during engine warm up (if you start a mission from parking).
18. Instruments and switches function correctly with all interdependencies.
19. Correct Venturi tube modeling in UP-1 gyro, KI-10 gyro modeling.
20. Engine start and turning off procedures fully correspond to the pilot's manual.
21. Landing gear bays and flaps affect flight dynamics correctly in all possible landing gear and flaps combinations (including flaps being lost).
22. Neutral virtual flight stick position corresponds to the real joystick flight stick position for FFB and regular joysticks (taking into account the elevator trim and fixed trim tabs).
23. Aircraft balance changes correctly in an event of fins or fins control rods loss for FFB and regular joysticks (taking into account the fixed trim tab position on the left aileron and both elevator trim tabs).
24. Fins with broken control rods correctly re-orient themselves when the air flow speed drops, affecting the FFB neutral position."

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8 hours ago, JtD said:

I've updated the original table in the first post. No data has changed, but a couple of new planes are included.

 

My primary issue, the Yak-7 does not make sense at all. By now it looks like there is a different sort of aerodynamics at work as soon as an aircraft is powered by a Klimov. I have included it twice because the devs gave a range of 19-20s for the turn time. It should be noted that this figure is already considerably worse than some data available for the plane, so hats off for not blindly following implausible figures to the very end. I still think it is too optimistic, it definitely is when compared to other aircraft.

 

Some of this is down to an apparent change in FM modelling philosophy, resulting in generally higher efficiencies with newer planes. I just hope they find the time to update the older FM's accordingly.

 

Good news is the A-20 at combat power without bombs has no problem out-turning any German fighter in game at sea level in a sustained turning contest.

 

 

bla002.jpg

 

Can you check the wing area number for the P-39? Wiki says 19.8 not 29.8 and 29.8 makes a mockery of the CLmax calculation- so I suspect a typo in the tech specs rather than a mistake in the game itself. 

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9 hours ago, JtD said:

A-20 at combat power without bombs has no problem out-turning any German fighter in game at sea level in a sustained turning contest.

 

I wondered at this as well. I make no claims about its realism, but when I first played the update trying to take out an A-20 in QMB was the first thing I did. Second thing was dogfighting in it since I noticed I was being out-turned and that had been a pretty successful endeavor. 

 

I tried looking for more information on the A-20 regarding its maneuverability, but most I've found was on its deployment as a night-fighter in it's P-70 configuration. One article I found on the P-70 only stated victories against bombers.

 

The P-70 does have heavier armament and the closest we can get to this configuration is by removing bomb-loads for the A-20 and perhaps even reducing fuel load. That said it does look to be quite formidable on its own as some kind of fighter, but what interests me is what other possible victories the A-20/P-70 has had as an actual fighter. 

 

The A-20/P-70 wasn't exactly a popular plane so I'm pretty curious about it's combat history myself and just how it was employed it air-to-air combat. 

 

This is a very interesting plane indeed. 

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8 hours ago, Panthera said:

 

I dunno seems a bit far fetched if it can outturn the German single seaters, esp. sustained :D

 

Just looking at the basic numbers ~9200 kg, 43 m^2 and 3200 hp, I can't see it coming close to the single seaters. Running the math the difference is quite stark infact. The Bf-110 looks a lot more favorable though, but still not superior to the single seaters.

 

9200kg includes eight 104kg bombs, standard weight is just 8366kg. Also, it has a high aspect ratio wing, with a span of 18.7m. This is tremendously important for a low induced drag and helps the A-20 a lot in low speed performance, including sustained turns.

The drawbacks of high aspect ratio wings are that they either are thick and high drag profiles but can be easily built to be sturdy, or they are thin and low drag profiles, but are not easily suitable for high loads. The A-20 designers did a good job there, probably based on their extensive knowledge gathered with the DC-2/3, which in the mid-30ies were cutting edge in structural design.

 

7 hours ago, LukeFF said:

If you're being out turned by an A-20 while flying a 109, you've done something terribly stupid and deserve to be shot down.

 

Yes, you've entered a turning fight with an aircraft that outturns you. You also deserve to be shot down if you've entered a turning fight with a Yak-7.

 

4 hours ago, unreasonable said:

 

Can you check the wing area number for the P-39? Wiki says 19.8 not 29.8 and 29.8 makes a mockery of the CLmax calculation- so I suspect a typo in the tech specs rather than a mistake in the game itself. 

 

Yes, it is 19.8, and as you say, it can only be a typo. It doesn't effect efficiency, so I'll just leave it in for now.

 

3 hours ago, MarderIV said:

That said it does look to be quite formidable on its own as some kind of fighter, but what interests me is what other possible victories the A-20/P-70 has had as an actual fighter.

 

In the entire war, all medium and light US bombers together claimed about 900 aircraft destroyed in the air. This includes B-25, B-26, A-20 and A-26. It also includes the claims from gunners, and it comes with the overclaim factor all claims come with. All in all this figures is very low. The A-20 as such just wasn't used as a fighter, it wasn't send out to take down other aircraft, and their opponents typically had larger threats to worry about (for instance, the large bombers).

Edited by JtD
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5 hours ago, JtD said:

 

9200kg includes eight 104kg bombs, standard weight is just 8366kg. Also, it has a high aspect ratio wing, with a span of 18.7m. This is tremendously important for a low induced drag and helps the A-20 a lot in low speed performance, including sustained turns.

The drawbacks of high aspect ratio wings are that they either are thick and high drag profiles but can be easily built to be sturdy, or they are thin and low drag profiles, but are not easily suitable for high loads. The A-20 designers did a good job there, probably based on their extensive knowledge gathered with the DC-2/3, which in the mid-30ies were cutting edge in structural design.

 

Oh I'm not trying to diminish the excellent work of the Douglas engineers, but I have to say that it's still not likely that it would outturn the single seaters, esp. in a sustained turn fight. It would definitely perform nothing like it does ingame atm, not even close, I'll even bet you a collectors aircraft on that one :biggrin:

 

The biggest problem for the A-20 in terms of drag is it's sheer size, both in terms wetted and frontal area, and this means that even if assuming everything else was equal it would still need more than just double the power to achieve the same thrust to drag ratio as the single seaters. Size really matters a lot when it comes to drag and therefore sustained performance.

 

That said, let's not forget that the Bf-110G2 featured both a lower wing, power & span loading than the A-20 all at once, plus it featured slats, yet ingame it doesn't even approach the same turn performance in either the instantaneous or sustained realm. 

Edited by Panthera

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