Yakcopter or Automatic flaps? + Video

[Maxyman]

И.К. Почему? Первое и самое главное – в кабине «мессера» сидел классный летчик! Вот поэтому я и не одолел. Остальное несущественно. Главное – лётчик! "

And you know the interview and the next question about how much fuel Kozhemyako had.

[JtD]

While I have no issue with reading a little bit of Russian every now and then, this is the international forum with English as the forums language. Would you mind putting it through Google translate or something first and post it then?

Edited November 27, 2015 by JtD

[NachtJaeger110]

You think? Well, very specifically, the top speed of the Yak-1 S69 was 535km/h at 6000m. In game it's flying 580km/h. This has been brought up like a year ago. Not remedied.

 

There must be some documents in russia that state the exact values we see in the game. Just take the Book "Bf 109 vs Yak-1/7: Eastern Front" by Khazanov and Medved that came out this year.

it states on p. 23 for the Yak-1 with M-105PF engine:

 

"Despite the weight penalty, the Yak-1’s performance was appreciably

boosted by the M-105PF –the zero-altitude speed increased by 27km/h (17mph), and

at altitude its top speed was as high as 575–80km/h (357–60mph). The rate of

climb was increased, and the time taken to fly a complete circle reduced"

 

 

Of course this is not scientific literature and the authors thankfully didn't provide sources in footnotes.........

but the authors must have come up with these numbers somehow and this could be the same source the Devs used.

Since the Devs stated that all their data comes from russian archives, there is not much we can do apart from flying to russia

and try to get Access to the archives which is not as easy as in western countries I've heard.

Edited November 27, 2015 by NachtJaeger110

[Matt]

Critical altitude was ~4000 meters for the M-150 PF. A top speed of 575 km/h at that altitude is fine, but not 2 km above that altitude.

 

But to come back to the flaps, the effect of the flaps is not really questionable imho. Above clean stall speed, the flaps offer no advantage (even if you see people using them at higher speeds).

 

The actuation of the flaps is too simplified, because the neutral setting is missing. I still have my doubts that the flaps of the real plane would behave exactly like they do in BoS with the lever set to extended position.

[6./ZG26_5tuka]

But to come back to the flaps, the effect of the flaps is not really questionable imho.

Hey Jay, if you are interested you might look into this:

 

- critical AoA with flaps 100% deployed

- energy rentention (with vs without flaps)

- verical manouvrebility with flaps 100% deployed

- climb test (max sustainable angle, min airspeed) with max deployed flaps

 

Should make it easier to comprehend what the complaints of the Yak flaps are about.

 

[Maxyman]

- energy rentention (with vs without flaps)

Question: how many witch hunters have tested this change:

15. Yak-1 pneumatic flaps extension speed increased (~80° per second while stationary, less at high speeds) based on learning video for Yak-15 with the same flaps system - http://forum.il2sturmovik.com/topic/168-developer-diary/?p=305444

[6./ZG26_5tuka]

Question: how many witch hunters have tested this change:

15. Yak-1 pneumatic flaps extension speed increased (~80° per second while stationary, less at high speeds) based on learning video for Yak-15 with the same flaps system - http://forum.il2sturmovik.com/topic/168-developer-diary/?p=305444

Counter question: How does that relate to what I wrote?

 

Flaps extension speed has nothing to do with faulty aerodynamics.

[Dakpilot]

@ Max , None....too busy with the T34 - Pzkpfw III (where's my Pz IV?) performance debate          ​

 

Seriously though, very surprised not too see a single comment about what it has changed along with the IL-2

 

Cheers Dakpilot

Edited November 27, 2015 by Dakpilot

[JtD]

There must be some documents in russia that state the exact values we see in the game.

They don't, unless it they are using fantasy stories as reference. The performance for the S69 is very well documents with the 6915 tests done. The top speed of 571 was obtained at 3850m, and is about accurate in game. High altitude performance on the other hand is completely off. Edited November 27, 2015 by JtD

[JtD]

...

- energy rentention (with vs without flaps)...

It's a lot worse with flaps extended. As it should be.

[6./ZG26_5tuka]

It's a lot worse with flaps extended. As it should be.

That's fine but in the end it's the proporsion that counts. Especially considering the often practised "energy climbs with flaps extended" this might be well worth an investgation.

[Sokol1]

 

how to do a screen shot

[Maxyman]

Counter question: How does that relate to what I wrote?

 

Flaps extension speed has nothing to do with faulty aerodynamics.

I take your answer a no.

Flaps speed affects energy retention. There is a direct relation.

Seriously though, very surprised not too see a single comment about what it has changed along with the IL-2

Devs handle constructive claims very well in my opinion. As long as valid references are provided.

[indiaciki]

idiots fly high speed combat with flaps - even if they don't rip off..If you don't get it it's not worth explaining. Opponents not taking advantage of this stupidy deserve being shot down.

Edited November 28, 2015 by indiaciki

[6./ZG26_5tuka]

I take your answer a no.

Flaps speed affects energy retention. There is a direct relation.

Again, this doesn't solve faulty aerodynamics. If a Yak with flaps extended can climb till 30km/h at an 45° angle before stalling it's just wrong no matter the extension speed of flaps.

 

That's what I had in mind when writing "energy rentention". Specifically dive and climb tests perfromed at determined alts and speeds till stall speed is reached, than comparing the delta alitude. With current flaps mechanics he Yak does climb worse with flaps extended in average, though especially in the low speed rane it climb well further due to a much lower stall speed. That's why I said it's the proportion that counts.

 

But I guess defending a point that does not go with yours just makes me a fanboy or witch hunter so why do I even bother explaining it to you.

Edited November 28, 2015 by Stab/JG26_5tuka

[Maxyman]

Again, this doesn't solve faulty aerodynamics.

Flaps speed is accurate now. That's how it works in engineering. What have you done to support your claims?

 

Amazing, you have 0.0 hours in Yak-1 but you know exactly how she should fly. And there's a number of people with similar attitude.

Edited November 28, 2015 by Maxyman

[YSoMadTovarisch]

Flaps speed is accurate now. That's how it works in engineering. What have you done to support your claims?

 

Amazing, you have 0.0 hours in Yak-1 but you know exactly how she should fly. And there's a number of people with similar attitude.

 

Flaps speed is accurate, what's not accurate is the ability to prop hang with flaps out and the suspicious energy retention vs lift in maneuvers

[Maxyman]

Flaps speed is accurate, what's not accurate is the ability to prop hang with flaps out and the suspicious energy retention vs lift in maneuvers

Roger that.

[6./ZG26_5tuka]

Flaps speed is accurate now. That's how it works in engineering. What have you done to support your claims?

 

Amazing, you have 0.0 hours in Yak-1 but you know exactly how she should fly. And there's a number of people with similar attitude.

And, whats your point? Do you have a pilot license? Do you actually understand aerodynamics or are you just here to tell people how stupid they were?

 

As I believe in the later case this my last answer you'll get.

[Askania]

 

 

Askania, on 26 Nov 2015 - 18:23, said: И.К. Почему? Первое и самое главное – в кабине «мессера» сидел классный летчик! Вот поэтому я и не одолел. Остальное несущественно. Главное – лётчик! " And you know the interview and the next question about how much fuel Kozhemyako had.

 

 

pilot skill is the major determining factor in a dog fight.

[Maxyman]

And, whats your point? Do you have a pilot license? Do you actually understand aerodynamics or are you just here to tell people how stupid they were?

 

As I believe in the later case this my last answer you'll get.

I don't tell people how stupid they are. And I don't think that people are stupid.

 

What I don't understand is your motivation to claim everything is "faulty" without supplying valid references and test data. It's counterproductive and doesn't help to identify problems.

I do realize that building a WWII fighter FM is a significant challenge. I assume it's not a trivial task to verify the FM based on limited historical references.

[6./ZG26_5tuka]

What I don't understand is your motivation to claim everything is "faulty" without supplying valid references and test data.

You can't prove anything to a satisfactory point. Can you prove the Bf109 couldn't dive at Mach-1? Can you prove the Fw190 oculd sustain 25G? No, because tests in this category were not carried out as far due to safety sake.

Equally, why should sby test a plane under high angle of attack with landing flaps deployed? It's like running against a brick wall just to figure out weather it hurts.

 

Again, 777 have aeronautic engineers in their team. That does not mean everything they present has to be perfect, but it means they should be able to review their work based on reports like this, or maybe the Fw 190 tailwheel I reported a while ago (without exact data), and eventually determine the issue.

Edited November 29, 2015 by Stab/JG26_5tuka

[Matt]

- critical AoA with flaps 100% deployed

- energy rentention (with vs without flaps)

- verical manouvrebility with flaps 100% deployed

- climb test (max sustainable angle, min airspeed) with max deployed flaps

 

1. Is smaller with flaps 100% deployed.

2. Is much worse with flaps deployed.

3. Please specify "vertical maneuverability".

4. Max sustainable angle is much smaller, min airspeed is lower with maximum deployed flaps. Rate of climb is reduced considerably.

 

Does this agree with the results from the tests that you've done? 

Edited November 29, 2015 by Matt

[6./ZG26_5tuka]

3. Please specify "vertical maneuverability".

How much elevator authority you have at a certain min speed with flaps undeployed / 100% deployed, specificly in a high pitch angle lcimb (45°+).

[Matt]

Elevator authority is reduced with extended flaps, that's true for all planes in BoS/BoM as far as i'm aware off.

[JtD]

That's fine but in the end it's the proporsion that counts. Especially considering the often practised "energy climbs with flaps extended" this might be well worth an investgation.

If this was worth an investigation, you as one of the loudest complainers should go ahead and investigate, in particular since you seem happy to ignore the results obtained by others.

[6./ZG26_5tuka]

Show me any valid test result I ignored. Don't spread rumors around here.

 

I know I shouldn't mind your comment but maybe it serves others for a purpose so here's a quick demonstration of the climb test:

 

NOTE: Due to the fact I had to record it and switch views I got slightly different results in the video. Still the margin of error is small.

 

The picture below was taken after the recording.

 

Test procedure: Yak-1, 60% fuel = 244 litres, no additional equipment, Custom difficulty (Expert with external views, markers, interface, unlimited fuel), Stalingrad Map Summer, 1:00PM, air spawn (2000m)

Power setting: 100% Throttle, 100% RPM, 100% radiators open, mixture 100%, low supercharger gear

https://www.youtube.com/watch?v=JcDFCbFDnKo&feature=youtu.be

 

Black line = Level line

Orange line = Main airfoil chord angle

Red line = Effective airfoil chord angle

 

Observations:

- Vstall with flaps retracted: 140 km/h

- Vstall with flaps extendet: 115 km/h

- delta Vstall for flaps retracted / extendet condition is ~ 35 km/h

- flap deployment angle during the climb test was approximetly 44.28° (calculated via Gimp)

 

Conclusion:

- the flaps cl coefficient for high pitch angles (30.87°) seems too high, delta Vstall too big (most likely stall speed with flaps extendet is too low)

 

Possible cause:

- faulty cl/cd relation

- faulty stall speed calculation

 

Again this is a basic test. Don't take this as 100% accurate but high approximation of ingame performance.

 

If you have a plot of the Yak-1 airfoild with flaps extendet (~45°) I'd be thankfull if you could share it.

Edited November 29, 2015 by Stab/JG26_5tuka

[Reflected]

I have a hunch where the mistake lays. To repeat myself: lowering flaps should actually lower the critical AoA. So, if you can pull 40 degrees with flaps up without stalling, you should only be able to pull less than that with the flaps down, and flaps down I mean compared to the new chord, between the leading edge and the tip of the flap. To put it in another way, lowering flaps will suddenly increase the AoA of the wing, as well as decrease the maximum you can pull.

 

I think - I just think, I cannot prove it - that flaps in BoS create extra lift and drag as they should, but the engine may not calculate with the change of "AoA tolerance" and/ or the change of chord. For example, you get your extra lift, your extra drag, but the engine still calculates the angle between the airflow and the flaps up chord, not the flaps down chord. 

[JtD]

Show me any valid test result I ignored. Don't spread rumors around here.

You keep claiming that energy retention flaps down is wrong, and you don't even care that for instance my tests, the most detailed posted yet, show that they are somewhere between spot on and maybe slightly optimistic. So, please - comment on that instead of repeating a generalisation that is not based on fact.

 

The picture below was taken after the recording.

And it shows very little. For instance, as you weren't flying level, what relevance does the level line have?

 

Conclusion:

- the flaps cl coefficient for high pitch angles (30.87°) seems too high, delta Vstall too big (most likely stall speed with flaps extendet is too low)

If you want to determine flaps lift, drag and AoA characteristics, I recommend you test it in level flight, power off. You have no idea what AoA the wing has in your test, nor do you know lift and drag, because they all are subject to prop generated airflow. Some aspects of which have been discussed in this topic already.

 

While I disagree with your method and conclusions, I do appreciate you posting this, because only this way any meaningful discussion may develop.

Edited November 29, 2015 by JtD

[6./ZG26_5tuka]

You keep claiming that energy retention flaps down is wrong, and you don't even care that for instance my tests, the most detailed posted yet, show that they are somewhere between spot on and maybe slightly optimistic. So, please - comment on that instead of repeating a generalisation that is not based on fact..

I never sayed anything about your test. You must have made that up yourself.

And it shows very little. For instance, as you weren't flying level, what relevance does the level line have?

When flying level the chord line angle = wing incidence.

While I disagree with your method and conclusions, I do appreciate you posting this, because only this way any meaningful discussion may develop.

That's fine. I said it's nto 100% accurate (which isn't possible without proper FM testing tools, dev ressources and plot tools). Unfortunately this is a very time consuming way of a meaningfull discussion (it took me 45min to record, edit, upload and post all of this) so I usually avoid it for good.

 

Again, it's not easy to proof some issues as detailed as required with our primitive methods we have.

[Matt]

Best i could find for Clark Y-H.

[JtD]

I never sayed anything about your test. You must have made that up yourself.

I never said you said something about my test. You're making that up.

When flying level the chord line angle = wing incidence.

Yes, and you weren't flying level.

 

 

Best i could find for Clark Y-H.

Pretty good.

[6./ZG26_5tuka]

Yes, and you weren't flying level.

What else should we take as a refference line than? Because that's what we need to figure angles and compare them.

 

About the chart:

 

I assume the alpha is the main chord angle in the airfoild + flaps diagram? Also, do you know what c.p. (upper diagrams) stand for? Can cl / cd be calculated with this?

[Reflected]

Great Chart, Matt! Now we should somehow test if the angle between the black and red lines on Stuka's picture can actually get higher than 15 degrees without stalling. That would prove something is wrong. But how do we test it? Stuka's tests were a good idea, but he wasn't flying level, so there is no way to tell the direction of the airflow on the picture.

 

Stuka, perhaps you could repeat the same test, but:

- don't switch between views

- concentrate on keeping the altitude constant - this will be tough

- record from the beginning, then you can switch between views when you replay

 

If you manage to do this we can get a fairly good idea of the AoAmax of the Yak with flaps down, and we can compare it to Matt's charts.

[JtD]

What else should we take as a refference line than? Because that's what we need to figure angles and compare them.

You would need to either fly level (reducing speed to stall impossible with high power settings), or you need to calculate true air speed and calculate your vector using that and your climb rate.

 

About the chart:

 

I assume the alpha is the main chord angle in the airfoild + flaps diagram? Also, do you know what c.p. (upper diagrams) stand for? Can cl / cd be calculated with this?

Generally alpha in NACA charts is main chord line. I haven't checked that document yet, but I'd be surprised if it was different here. C.p. is centre of pressure in % of the chord, useful for calculating moments. Cl/cd cannot be calculated with this. ClarkYH with flaps data isn't as plenty as say for the plain ClarkY or the 23000 series, so it might be necessary to make up one's own mind. It should also be noted that using just one source is not good, if you look at 10 diagrams from 10 wind tunnel tests, you'll find 10 different results - depending on wind tunnel properties, test procedures, evaluation algorithms & airfoil details outside of profile.

[II./JG77_Manu*]

A little less then a year ago i left this Sim, and didn't follow or carry on any of the tests and researches i did. Put a lot of work into it, and the reluctance of the Devs towards it just doesn't make the effort worth it (while they fixed the 190 after a huge load of hard data provided by a lot of different people, they didn't even really admit it, that it has been wrong before) I decided back then, to just leave, let it be, don't play the game anymore, don't get pissed off.

Now after a long time, coming back, the Sim really has evolved, and became quite fun to play. Stuff like dynamic multiplayer campaigns starting etc, i just can't stay away anymore...

But i had to realize that the Yak is still borked as hell - maybe more then ever? Don't really understand it, because the other 9 planes (+ the BoM one's as well, as far as i have seen) seem perfectly fine.

I more or less already accepted that the Yak in game performancewise matches pretty much the best Yak1b ever built at low to mid altitude (Nr. 46139), and has some magic high alt booster, apparently lost in soviets secret technology books...

but after ongoing 1v1 duels against competitive pilots out of my squad, i also realised that the flaps behaviour is way off. I don't need any hard evidence, any NACA tunnel tests, or any performance tests what so ever, to understand that it's off.

JtD, Matt, i honor your purely objective, and scientific clinical approach towards any issue in this game...but there are just things, that can't just be measured in any in-game or real life data. To actually realize that the Yak is off, you have to fight with and against it in a duel against another copetitive pilot. I started lately with my squadron, to do duels in BoS, because we are slowly getting started to get into BoS (beeing mainly a 1946 squadron, participating in SeoW etc). We are regularly making 1v1 and 2v2 duels, because there is of course no faster way to become competitive as a fighter - we have one ridiculously good pilot, i am always loosing to him in 1946 1v1 duels, even in "off-duels" like he is in a P39/40, and i am in a G2 or so. Last time we went into BoS training..1v1..first 109 against 109..the old game, i always lost. Then i went over to the Yak..first without using flaps at any point, getting my first hits and kills, maybe around 20:80 in favour of him. Then i started using flaps, and the Yak become a wonderplane. Turning like a Chaika - no kidding, i took it sometimes in 1946 training -, not stalling what so ever, you can actually go straight vertical till zero speed, and still be a stable gun platform hitting what you want. He was trying everything he could. First he speed passes with huge energy advantage, but Chaika-like i could turn into him anytime, setting up for head-on. Avoiding that, he started to bleed a little of his energy, and started to Yoyo me in ongoing vertical manouvers. I just turned (still with flaps of course) out of his attack angle - and he is a hell of an angle shot - and at the critical point turning back into him, getting shots on him regularly while he was zooming up again. The K/D ratio now highly favoured me. He could do nothing, apart from some perpendicular angle shots which hit me (99% of pilots would have no chance to hit them i guess). He, pretty new to BoS, also said, he has never seen anything like this, in any sim ever. I felt like i was cheating.

Let's get to the facts we have:

There are no accounts what so ever, who mention that the Yak is becoming a better fighter, when deploying flaps. While there are certain planes, known for "combat flaps usage" like the P40, or the P51, even the 109 (10% flaps mentioned in trainings, for better turnfight behaviour), there is nothing about the Yak using the flaps apart from landing ,there is no combat flaps stage as well. The (one-stage) landing flaps of the Yak are far lowered, comparable to ~70-80% of the 109, or landing position of the Dora or Mustang. No plane on earth used such far lowered flaps in a combat situation. If this would be useful, it would be common knowledge, and would have been teached.

It also doesn't work with other planes. I tried it with all the other planes, La5, Lagg, 109, 190, fully lowered or comparabale lowered flaps. They behave nothing like the Yak. They become very twitchy and wobbly (whereas the Yak is very stable in this condition), and you also can't trick the stall with those planes, like you can do it in the Yak. Quite the opposite, the other planes stall even more/sooner, the more you extend the flaps while turning sharply. With all the other planes the flaps feel realistic (/=comparable to my real life flying in Aero At3 and Cessna's). I can fully understand 5tuka, because i know he is a real life pilot himself, and you just immediately know, that there is something fishy, when you use the flaps with the Yak. If someone can give me some valuable explanations for those points (1. why does no other plane behave like the Yak with flaps extended, 2. why are there no accounts, no sources, that tell you to use the flaps in the Yak, 3. why is there no "combat stage" for the flaps, like it is in the P51 for example), i might rethink. But i have never ever seen any explanation for those points..i am almost sure there is no.

And you don't have to look for any "historical data, evidence, bla" to know that there is something wrong. How on earth should there be evidence, that the flap behaviour can not be like it is right now?? Like 5tuka already brought to attention, it would be the same with the 190 diving with mach 1,5, somebody saying there is something wrong, and people would cry for "historical evidence", that the 190 can not do mach 1,5.

There is no evidence about stuff, that's so obvious to not be possible.

 

I am pretty sure, the Devs won't change a thing in this weird behaviour. Why should they, nobody can proof them wrong, because there is no evidence about it. I definitely won't spend any more of my time to persuade clueless people, or even the Devs to change it, because it will bring nothing positive. I just hope, in the next theatres we won't get broken planes.

[1PL-Husar-1Esk]

There is list of broken FM in history of Devs - some of the Rise of flight planes. Why BoX shuld be diffrent. Enjoy what we have

Edited November 30, 2015 by tomcatqw

[JtD]

Well, I'm not objectively trying to analyse "if" something is wrong, but "what exactly" is wrong. I think we're way past the "if". Analysing things to me at least is helpful, educational and entertaining, while repeated whining will only help emotionally and that only for a short time.

 

As for the Yak's "what exactly", we have definitely wrong

- high altitude performance,

 

very questionable

- auto retract and deploy feature as modelled in game

 

borderline optimistic, but not necessarily wrong

- flaps down lift coefficient

- flaps drag

- prop wash effect (effecting both low speed lift and control)

 

unquantified

- control properties flaps down

 

correct

- low level speed

- stall speeds power off, lift coefficients (160 clean, 145 flaps down, cl's 1.38 / 1.68)

 

It would help me and probably the case if folks while beating a dead horse, would at least beat the right one.

 

p.s.: If someone in an I-15 would do the below in game, would you think that low speed handling and control of the aircraft is so obviously wrong, that evidence would not be necessary?

 

https://www.youtube.com/watch?v=-zrvmQyiQ5Q&feature=youtu.be&t=252

Edited November 30, 2015 by JtD

[Matt]

Well, since the high altitude performance is definately wrong (and that can easily be verified), it makes more sense to me, that the devs take a look at that and fix that first. Then one could see what caused the too high performance and if fixing this also has an impact on the behaviour with flaps down. Too high performance is either drag or thrust related and this could have a pretty big impact on overall behaviour if something is seriously out of order. It doesn't seem to have anything to do with the critical altitude of the supercharger gears (which could've been an easy explanation), because the manifold pressure seems to drop correctly at higher altitudes. 

 

That's the only suggestion i will have.

Edited November 30, 2015 by Matt

[6./ZG26_5tuka]

Well, since the high altitude performance is definately wrong (and that can easily be verified), it makes more sense to me, that the devs take a look at that and fix that first. Then one could see what caused the too high performance and if fixing this also has an impact on the behaviour with flaps down. Too high performance is either drag or thrust related and this could have a pretty big impact on overall behaviour if something is seriously out of order. It doesn't seem to have anything to do with the critical altitude of the supercharger gears (which could've been an easy explanation), because the manifold pressure seems to drop correctly at higher altitudes. 

 

That's the only suggestion i will have.

That would be a good start.

 

(General discussion) While not nessecarily having the right tools at hand to proof it the behaviour some people (including me) call wrong is definetly present ingame. I agree it needs to be verified to be solved properly, I agree this requires more than pure talk. BUT just because sby isn't able to express or test this issue in a scientific matter that would lead to the direct source of the issue in the FM does not mean his observation is totally wrong and the ingame model totally correct, like some (not aimed at anybody soecifically) try to put it.

 

If more people shared their observations and mindset for working out proper FM test methods in order to help verifying one issue discussions could run on a different, way more productive course. But unfortunately it's only individuals that take all the effort of verifying bugs hoping to acchieve improvement on the game while being flamed down by other people rejecting any changes to the sim.

 

As far as my test goes I agree with your points Reflected and JtD. If I retry the test I will make sure to use different power settings (low/power off) and keep the climbrate at 0, though I've got some serious buisness this week.

Edited November 30, 2015 by Stab/JG26_5tuka