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Me262 pitch authority

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Posted (edited)

The issues as I see them (feel free to "pitch in" *wink wink* ;) )

 

1) Elevators are too ineffective (should remain effective enough for the pilot to be able to enter an accelerated stall at most speeds (within pilot G tolerance) via these without any need to apply trim. Note: a key advantage of a trimmable tailplane vs trim tabs or trimmable elevators is that you retain full elevator deflection and thus increased relative effectiveness of the elevators at speed)

2) Speed related pitch up/down is too severe and the aircraft requires excessive trimming (looking at the design & layout of the 262 and comparing it with the conventional types, as well as considering what is written in the manuals regarding trimming, this effect should be much less pronounced)

3) (Related to nr.2 issue above) Trimmable tailplane is too ineffective/insensitive (as pr. the manual the 262 should require only small changes in trim with speed, as only a small change in incidence of the tailplane would result in a large effect in trim) 

 

Finally I agree that in general the developers really did a splendid job with this aircraft, esp. the engine modelling is great, it's really only the above issues which are holding it back IMHO, but I have confidence they will fix :)

 

 

Edited by Panthera
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Using trim settings based around the 'level trim' marker line on the gauge next to the elevator trim handle (+1 to +1.5), it flies great.  While I couldn't quite get the gunsight on, I was able to follow an AI La5FN somewhat closely for 3 or 4 right-hand AI circle turns (you know the kind of turn I'm talkin' about). 

 

I'm not sure it is possible to accelerated stall it without some high angle vertical maneuver and a rapid loss of speed.  This may be really how it was.  

 

I'm also not sure one could actually pull a blackout-strength turn like we see in the prop fighters.  Again, I'm thinking IRL that there had to be  specific circumstances to pull enough G to blackout.  

I haven't been able to blackout a pilot yet, but there were a few points (I believe) that the pilots vision should have started to grey-out around the edges but, there was no effect.  

IMO, the early signs of G-LOC due to a tight turn might be set to trigger a slight bit earlier.  Just a little tightening of field of view with a grey-out border in sustained or higher G would seem about right. 

 

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Try it after hotfix, thanks everybody for your attention, there was a bug in release build with elevator chennel indeed. Check the plane in different  loading configurations and you will by surprised how Me262 changes its behaviour depends on position of center of gravity.

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On 6/10/2019 at 10:02 PM, Panthera said:

Have just taken the Me262 through it's paces and I have to say the FM feels very strange, esp. the lack of pitch authority comes across as very perculiar (bug?)

 

THe problem is so bad that atm you cannot even force an accelerated stall, infact you're mostly not even capable of making the slats come out. Blacking out is also basically impossible.

 

This could ofcourse all be down to bugs, which I have to say I hope is the case.

 

Well salute Panthera.  Good call:salute:

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1 hour ago, IAmNotARobot said:

Try it after hotfix, thanks everybody for your attention, there was a bug in release build with elevator chennel indeed. Check the plane in different  loading configurations and you will by surprised how Me262 changes its behaviour depends on position of center of gravity.

 

That is great news, I hope the speed related trim has been fixed too, looking forward to trying it out after the hotfix and will make sure to report back :)  

 

Thank you for the quick reaction time! 😊👍

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Posted (edited)

For me it looks much better now on the elevator axis but ruddder axis still looks too sensible.

Thanks for the fast fix.

Edited by E69_geramos109

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Elevator much better now.

 

Thank you.

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Plane has low stability in rudder channel because of swept wing design, not a bug)

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Posted (edited)

Alright just had a go in the 262 after the hotfix and things have definitely improved, with now both a markedly reduced pitch up/down with speed and a more effective elevator as compared with before. However it's still not quite there IMO and there are a few issues left, incl:

 

1) The slats: Whilst you're now able to put the aircraft into an accelerated stall more easily, curiously the slats don't come out neither before or during the stall. In reality the slats would begin to come out gradually as the wing gets close to its critical AoA, and infact usually be fully out a few degrees prior to this.  Importantly this happens completely irrespective of speed and relies completely on the stagnation point on the leading edge of the wing which creeps lower and lower the more you increase the AoA. 

This leads us to the 2nd problem with the slats ingame: They appear to be hard coded not to work past 450 km/h, which looks to be a case of taking what is mentioned in the manual a little too litterally and out of context, the reason being that handley page automatic slats feature no locking mechanism that would keep them locked past a certain speed, they are infact completely free working devices relying solely on air pressure to pull them out or push them in, and as such when sitting still on the ground they can actually be pushed in or out via the tip of a finger. In other words slats work at all speeds and will come out as soon as you approach the critical AoA, delaying the stall and thereby increasing the Clmax & critical AoA further. 

 

2) The trimmable tail plane: Still feels way too ineffective/insensitive, whilst according to all acounts it was almost too effective/sensitive, the aircraft requiring very little changes to trim with speed and pilots being adviced against trimming their way out of a dive as it could easily lead a sistuation of over controlling the aircraft.

 

 

3) The elevators still appear too ineffective: I say this as when trimmed for 560 km/h level flight I am still unable to induce an accelerated stall in the aircraft via the elevators alone, even at very low speeds. Looking at the design the of aircraft and the effectiveness of the tailplane as a whole, there should be no reason that even when trimmed for very high speeds (700+) you would not still be able to pull the aircraft into an accelerated stall at low speeds. The reason for this being that a trimmable stab design allows for full elevator deflection irrespective of trim setting, and since only a few degrees in incidence were needed to trim the 262, the effectiveness of elevators should remain high at all speeds irrespective of trim setting.

 

4) The elevator stick forces: I was able to notice quite a bit of reduction in stick travel with speed ingame (mirroring what @Holtzauge noticed), an issue that would make the above issue with elevator effectiveness seem even worse. I don't believe high stick forces was/is a problem the real aircraft faced at its operating speeds, with all accounts mentioning "light and perfectly harmonized controls up until max permissable speed" (950 km/h), which makes sense considering the 262's elevators featured servo tabs to lower the control forces at speed. The result of the high stick forces ingame is that it still isn't possible to black out the pilot via the elevators alone ingame, something which definitely should be possible at most speeds over ~500 km/h. (This is assuming an initiation of grey out at 6 G's)

 

 

In short the four things left to fix IMHO are:

1) The slats: They need to work & apply their effects at all speeds just like the real thing, i.e. they need to be out before any stall

2) The trimmable horizontal stabilizer needs to be more effective in accordance with design & pilot accounts, i.e. requiring a smaller percentage in change of incidence to cause the same amount of change pitch up/down. 

3) Elevator effectiveness needs to be increased enough to allow entering an accelerated stall at low speeds even when the aircraft is trimmed for high speed

4) Elevator stick forces need to be reduced in accordance with design & pilot accounts (this will likely help solve issue nr.3 above)

 

Once again I thank the developers for the attention to this issue and I am hoping/looking forward to further fine tuning of the FM :) 

Edited by Panthera

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All the references says that slats retracts at the speeds under 450-475 km/h no matter are you gliding or not. No mentions of high speeds extension. If you have any info about it we will tune its behavior. In lower speeds slats simulation takes into account local g-force, dynamic pressure and AoA, so you can by sure it is not just a script.

About pitch authority. We have a reference that pilot has to pull the stick with the force under 28 kg to achieve 3G on 3000m and EAS 800 km/h (not TAS) with adjustable stabilizer set so that horizontal flight (1G) takes 15 kg pushing force on stick. Creation of one more G requires 21.5 kg of pulling power: (28[kg] - (-15[kg]))/(3[G] - 1 [G]) = 21.5 [kg / G]. Considering that max pulling power with two hands can be something under 75 kg you can calculate max achievable G on 3000m and EAS 800 km/h - it equals 5.1 G. Anfortunetally there was no weight of plane in this reference (and as I said before the planes FM is really sensitive to loading configuration), so we tuned FM in a way to achieve described behavior with no weapon modes, 50% fuel and full ammunition.

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Posted (edited)
2 hours ago, IAmNotARobot said:

All the references says that slats retracts at the speeds under 450-475 km/h no matter are you gliding or not. No mentions of high speeds extension. If you have any info about it we will differently tune its behavior. In lower speeds slats simulation takes into account local g-force, dynamic pressure and AoA, so you can by sure it is not just a script.

 

The only thing I can find which could be interpreted as such is the following line in the rather brief post war manual initially given to Allied pilots:

Z16R9FO.png

 

If you ask me however the above is not intended to mean that the slats will stay in nomatter what above 450 km/h, instead it is to make the pilot aware that when the slats come out at this speed during a gentle turn or climb at what in a conventional aircraft would be considered quite a high speed, then it is perfectly normal and not something to worry about. I say this because them being locked in simply can't happen without some sort of system lock, which the 262 does not have :) In other words as soon as the stagnation point moves down far enough the slats will have to pop open, it's what they're designed to do and there would be no point in preventing them from doing this.

 

For confirmation you can see that it is worded differently in the briefing of Hans Fey (which the above manual was based on):

8ICFVRA.png

 

 

2 hours ago, IAmNotARobot said:

About pitch authority. We have a reference that pilot has to pull the stick with the force under 28 kg to achieve 3G on 3000m and EAS 800 km/h (not TAS) with adjustable stabilizer set so that horizontal flight (1G) takes 15 kg pushing force on stick. Creation of one more G requires 21.5 kg of pulling power: (28[kg] - (-15[kg]))/(3[G] - 1 [G]) = 21.5 [kg / G]. Considering that max pulling power with two hands can be something under 75 kg you can calculate max achievable G on 3000m and EAS 800 km/h - it equals 5.1 G. Anfortunetally there was no weight of plane in this reference (and as I said before the planes FM is really sensitive to loading configuration), so we tuned FM in a way to achieve described behavior with no weapon modes, 50% fuel and full ammunition.

 

Do you by chance have a link to said reference? It sounds very high, esp. compared to the other conventional aircraft of the period without any form of servo assist. Could this perhaps be without the servo tabs connected? I remember this was a factor in at least one Allied test where both the elevator & rudder servo tabs weren't connected)

 

Thankfully Captain Eric "Winkle" Brown, RAF's chief test pilot, is quite specific on the topic:

"The normal range of flight characteristics from aerobatic maneuvres to the stall revealed the Me 262 as a very responsive and docile aeroplane, leaving one with a confident impression of a first class combat aircraft for both fighter and ground attack roles. Harmony of controls was pleasant, with a stick force per 'g' of 2.72 kg (6lb) at mid-CG position and a roll rate of 360 degrees in 3.8 seconds at 645 km/h (400 mph) at 1525m (5000 ft)."

 

Source: Wings of the Luftwaffe: Me262 by Capt. Eric "Winkle" Brown, Page 252.

 

So as pr. Eric Brown who flew a Me262A1 with connected servo tabs (it was maintained & serviced in the UK by a German crew), it would take ~19 kg to pull 6 G's at 645 km/h, which is a lot more along the lines of what you'd expect from a servo assisted tailplane design such as the 262's. 

 

That being said you should also be able to black out the pilot in the 262 a lot sooner along the speed range than that, infact at something like 550 km/h if we assume a modest slatted Cl of ~1.4, a very high (for most pilots at the time) ~7 G's could be pulled instantanously at sea level. However ingame I am unable to black out the pilot even at 600-700 km/h via the elevators alone, something which should be easily possible according to the testing conducted by Brown with RAF.

 

Also as mentioned in the briefing of Hans Fey above, the aircraft was said to "turn much better at high speed than at low speed", which would seem to indicate the elevator forces were sufficiently light not to inhibit maneuvering at high speed. 

Edited by Panthera
Cleared a few typos

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21 минуту назад, Panthera сказал:

Z16R9FO.png

 

We simulated slats exactly that way. Incoming dynamic pressure can be much more expressed then aerodynamic sucktion force and g-force influence, that prevents slats to extend in higher speed.

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Posted (edited)
11 minutes ago, IAmNotARobot said:

 

We simulated slats exactly that way

The slats are not controlled that way. They dont come out based on speed. They are free and come out based on AoA. The video is contradictory even. It shows the slats coming out on the ground but then makes other statements

 

 

Edited by Fumes
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Just now, IAmNotARobot said:

 

We simulated slats exactly that way

 

Yes that I noticed :)  I think you took it too litterally however, as I don't think it was intended to be read as the slats being locked above 450 km/h (the mechanism feature no locking system), instead it was worded like that so as to make Allied test pilots aware that when the slats come out at this speed during a climb or gentle turn at what in a conventional aircraft would be considered  high speed, then it is perfectly normal behavior and not something to worry about.  Hence the original briefing didn't actually mention anything about turning.

 

I am quite sure of this as handley page slats don't care about speed, purely about the location of the stagnation point. As soon as the critical AoA is approached there is nothing which will stop them from coming up, they are infact forced out by pressure.   

 

 

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2 минуты назад, Fumes сказал:

The slats are not controlled that way. They dont come out based on speed. They are free and come out based on AoA.

 

I know how they works, thanks.

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2 minutes ago, IAmNotARobot said:

 

 

I know how they works, thanks.

No need to be snarky. Your previous post implies you think they work differently.

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1 час назад, Panthera сказал:

Do you by chance have a link to said reference? It sounds very high, esp. compared to the other conventional aircraft of the period without any form of servo assist. Could this perhaps be without the servo tabs connected? I remember this was a factor in at least one Allied test where both the elevator & rudder servo tabs weren't connected)

The reference is: "О потере продольной управляемости самолета при больших скоростях полета", Г. С. Калачев,1946 г.
It is a soviet post-war aerodynamic research of high Mach influence on aircrafts controlability, so I trust in it with full confidence.

 

 

39 минут назад, Fumes сказал:

No need to be snarky. Your previous post implies you think they work differently.

 

2 часа назад, IAmNotARobot сказал:

In lower speeds slats simulation takes into account local g-force, dynamic pressure and AoA, so you can by sure it is not just a script.

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Posted (edited)
17 minutes ago, IAmNotARobot said:

The reference is: "О потере продольной управляемости самолета при больших скоростях полета", Г. С. Калачев,1946 г.
It is a soviet post-war aerodynamic research of high Mach influence on aircrafts controlability, so I trust in it with full confidence.

 

Ok, but it would seem it was done with the servo tabs disconnected? The same  was the case in a post war US test which had similar findings, i.e. stick (& rudder) forces becoming high past 350 mph.

 

By comparison the RAF testing of Me262A1's with servo tabs connected, and maintained by German crews, established a stick force of 2.72 kg pr. G at 645 km/h (400 mph) and 1500 meters height. I really don't think this can be ignored.

Edited by Panthera
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34 минуты назад, Panthera сказал:

 

Ok, but it would seem it was done with the servo tabs disconnected? The same  was the case in a post war US test which had similar findings, i.e. stick (& rudder) forces becoming high past 350 mph.

 

By comparison the RAF testing of Me262A1's with servo tabs connected, and maintained by German crews, established a stick force of 2.72 kg pr. G at 645 km/h (400 mph) and 1500 meters height. I really don't think this can be ignored.

 

No mantion of servo disconnection in soviet reserch and any in other soviet Me262 manuals and discriptions that we have. On the contrary, they says that elevators have that servocompensation.

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I don't a have a good head for figures but the accuracy you guys are aiming, both the Devs and the people that is asking is superb. Thumbs up for the hard work, thanks.

 

I am sure if it is not already accurate, it will be.

 

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1 hour ago, IAmNotARobot said:

 

No mantion of servo disconnection in soviet reserch and any in other soviet Me262 manuals and discriptions that we have. On the contrary, they says that elevators have that servocompensation.

 

I find that very curious considering the very different findings of the RAF. I think this requires further investigation. 

 

One thing is for sure, if the RAF recorded a stick force of 2.72 kg pr. G at 645 km/h and 1500 m, then something significant would have to be wrong with the Soviet example if they werent even coming close to replicating this. The most likely theory IMO would be that the servo tabs were disconnected, but since you claim this wasn't the case then I am currently at a loss. 

 

 

 

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18 минут назад, Panthera сказал:

 

I find that very curious considering the very different findings of the RAF. I think this requires further investigation. 

 

One thing is for sure, if the RAF recorded a stick force of 2.72 kg pr. G at 645 km/h and 1500 m, then something significant would have to be wrong with the Soviet example if they werent even coming close to replicating this. The most likely theory IMO would be that the servo tabs were disconnected, but since you claim this wasn't the case then I am currently at a loss.

 

If you'll find original RAF (or someones else) research or test results it would be really cool and valuable. Don't know why, but is not that easy to find some aerodynamic researches and fly tests despite the popularity of this plane, the soviet data is the only reliable source of information on this problem that we have. Thanks for assistance by the way!

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Posted (edited)
1 hour ago, IAmNotARobot said:

 

If you'll find original RAF (or someones else) research or test results it would be really cool and valuable. Don't know why, but is not that easy to find some aerodynamic researches and fly tests despite the popularity of this plane, the soviet data is the only reliable source of information on this problem that we have. Thanks for assistance by the way!

 

You're most welcome, and thank you for the quick reaction and attention to the issue :) I will see if I can dig up the original documentation for the tests, or perhaps get someone else to give a hand.

Edited by Panthera
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I am very glad to see member of the team participating on the discussion. Thats is what comunity wants to see more often

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Posted (edited)

The Soviet figure of ~20kg/g is for 800km/h EAS at 3000m? So that's ~950km/h TAS or Mach 0.8.

 

I don't think that this in any way contradicts the RAF figures of 3kg/g at 650km/h at 1500m.

 

Mach 0.8 might have transsonic/compressibilty effects overlaying any true subsonic characteristics, and controls on the 262 might stiffen up just like they do on any other aircraft.

 

The manual says that when diving, you're supposed to trim the aircraft so that you need to push the stick, which implies that pulling out is not that easy, or at least that you don't need to worry about overloading the frame while doing so. You wouldn't have that clause in if you still were anywhere near 3kg/g in the high speed range, you'd kill pilots with that.

 

Thanks for the educational and interesting discussion.

Edited by JtD
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Given the 262 doesn't have any Slat locks or ADC input to the slats then AOA is the sole determinant of Slat position. I find it hard to believe some magic factor of "Q" overrides the forces imposed by AOA to prevent the slats deploying.

 

As to RAF test reports then Try the National Archives at Kew the have pretty much every Flight test the RAF has ever done there. We know they have AVIA 6/9201 as that is on the Performance testing page ... seek ans ye shall find.

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Posted (edited)
Quote

Given the 262 doesn't have any Slat locks or ADC input to the slats then AOA is the sole determinant of Slat position. I find it hard to believe some magic factor of "Q" overrides the forces imposed by AOA to prevent the slats deploying.

 

Correct, by design they will come out as soon as the wing approaches the critical AoA, the 262 featuring no locks to prevent this. I'm confident the developers will realize this as well.

 

Also thanks for the insight in regards to the archives at Kew Bert, I will try to contact them! 👍

 

 

15 hours ago, JtD said:

The Soviet figure of ~20kg/g is for 800km/h EAS at 3000m? So that's ~950km/h TAS or Mach 0.8.

 

I don't think that this in any way contradicts the RAF figures of 3kg/g at 650km/h at 1500m.

 

Mach 0.8 might have transsonic/compressibilty effects overlaying any true subsonic characteristics, and controls on the 262 might stiffen up just like they do on any other aircraft.

 

The manual says that when diving, you're supposed to trim the aircraft so that you need to push the stick, which implies that pulling out is not that easy, or at least that you don't need to worry about overloading the frame while doing so. You wouldn't have that clause in if you still were anywhere near 3kg/g in the high speed range, you'd kill pilots with that.

 

Thanks for the educational and interesting discussion.

 

Yes, however I still think it seems a bit high considering the forces at 650 km/h and 1500m. If it was M 0.86 @ 3000 m I would agree as we know the controls very soon after that became extremely stiff due to compressibility.

 

Either way atm we are unable to black out the pilot at any speed without "cheating" and using the trimmer, which really shouldn't be the case, but I think the devs can see that too when it only required 2.72 kg pr. G at 645 km/h.  Again if we assume a Cl of 1.4 youshould be able to black out the pilot in the 262 already at  ~500 km/h with elevator control alone pretty much irrespective of what speed you're trimmed for.

Edited by Panthera
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At Mach 0.86 the 262 was not controllable in pitch and nosed down, at 0.83 it was pretty tricky to pull it out of a dive.

 

It should be mentioned that the 6lb and 400mph Brown refers to are probably true air speed, not equivalent air speed - so these 400 compare to 580 in the Soviet test.

 

WRT to slats, if they were mass and friction free, everything would indeed depend on angle of attack only, but as they are not, operation also depends on dynamic pressure and local g forces. It's exactly NotARobot wrote.

 

Haven't tried the 262 in game, yet. So I'm not saying anything is wrong or everything is right, just commenting on the real life data.

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Posted (edited)

 

2 hours ago, JtD said:

At Mach 0.86 the 262 was not controllable in pitch and nosed down, at 0.83 it was pretty tricky to pull it out of a dive.

 

It should be mentioned that the 6lb and 400mph Brown refers to are probably true air speed, not equivalent air speed - so these 400 compare to 580 in the Soviet test.

 

At 645 km/h (400 mph) it is at this point in time not possible to pull full elevator deflection, or even enough to black out the pilot, in the Me262 ingame. 

 

2 hours ago, JtD said:

WRT to slats, if they were mass and friction free, everything would indeed depend on angle of attack only, but as they are not, operation also depends on dynamic pressure and local g forces. It's exactly NotARobot wrote.

 

Haven't tried the 262 in game, yet. So I'm not saying anything is wrong or everything is right, just commenting on the real life data.

 

Well since the slats work by means of air pressure, that is as soon as the stagnation point on the LE moves low enough they are forced out, the greater the speed the greater the pressure forcing them out will also be. In addition to this the 262's slats used a roller track mechanism where extension was further aided by any increase in G forces. So really they should work just fine at any speed where the critical AoA can realistically be approached. In other words it should not be possible to stall the wing without the slats having come out prior in order to delay this.

 

For comparisons sake the exact same roller track design is said to have been used on the F-86 where the limit of operation was listed as 0.65 mach (800 km/h), but then again the aircraft also couldn't enter an accelerated stall at that speed without disintigrating :)

 

 

Edited by Panthera

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Was busy doing some IRL flying this weekend (Discus b glider where the controls really stiffen up already at 200 Km/h IAS :happy:) so only got the chance to test the 262 after the fix now and things have really improved since you can now do accelerated stalls at much higher IAS than before the fix. However, as far as I can tell while you now have elevator authority to stall at higher IAS, the slats still stay in right up to departure which seems strange. Have not yet tested enough to determine if this is purely a visual thing but if you compare with the in-game Me-109 slat kinematics these seem to match the angle of attack better since they pop out as expected also at higher IAS if you pull enough g's. Given the high aerodynamic forces involved in the leading edge suction that pulls out the slats (ballpark an order of magnitude greater than the mass forces), I have a hard time seeing mass forces having any major impact on the kinematics, especially seeing those will act more or less perpendicular to the slat rails at higher aoa.

 

That being said, I'd like to join the chorus of users thanking IAmNotARobot for the fix and taking the time to interact with the forum community. The Me262 is great and a pleasure to fly and the tuning activities on the Me262 and the other planes in the sim are greatly appreciated! :good:

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Posted (edited)

Finally tried the Me262 in game, and can see where you're coming from WRT to the slats. Seems strange, but then I don't have detailed information about how they worked. If they were purely aerodynamic, then they're probably off.

 

I don't have issues with the current elevator authority. CoG has a huge impact, makes me wonder how exactly I reproduce RAF conditions in game. If I go in with standard loadout, I think I can get it to stall from neutral trim in the 400mph 5000ft scenario, at any rate, pretty close to stalling. Hard to notice, given that it does not spin, the slats don't come out and that it bleeds speed very quickly.

 

What I am wondering most, however - is the performance correct? I can get the speeds I expect, but even at full throttle cannot maintain a decent climb rate. Acceleration is very, very slow, too. Depending on altitude, I'd expect to outpace piston engined fighter at speeds of 500 and above, but this does not seem to happen. Has anyone already put numbers to climb rates and acceleration in game?

Edited by JtD

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Posted (edited)
7 hours ago, JtD said:

Finally tried the Me262 in game, and can see where you're coming from WRT to the slats. Seems strange, but then I don't have detailed information about how they worked. If they were purely aerodynamic, then they're probably off.

 

I don't have issues with the current elevator authority. CoG has a huge impact, makes me wonder how exactly I reproduce RAF conditions in game. If I go in with standard loadout, I think I can get it to stall from neutral trim in the 400mph 5000ft scenario, at any rate, pretty close to stalling. Hard to notice, given that it does not spin, the slats don't come out and that it bleeds speed very quickly.

 

What I am wondering most, however - is the performance correct? I can get the speeds I expect, but even at full throttle cannot maintain a decent climb rate. Acceleration is very, very slow, too. Depending on altitude, I'd expect to outpace piston engined fighter at speeds of 500 and above, but this does not seem to happen. Has anyone already put numbers to climb rates and acceleration in game?

 

Well realistically you should be able to put the aircraft into an accelerated stall at low speeds even with it trimmed for 650 km/h as the trimmable tailplane only needs very small change in incidence to cause a large change in pitch (something heavily weighed in the manuals), and since this type of design ensures full elevator deflection irrespective of trim it should be possible to generate more than enough downforce to cause an accelerated stall at practically any speed from lift off to 650 kmh whilst being trimmed for the latter. The reason being that full elevator deflection changes the camber and relative AoA of the tailplane to such a degree that the small upwards trim of the tailplane when trimmed for level flight at 650 kmh should have no noticable impact on actual pitch authority at lower speeds.

 

As for the performance, I'm not sure, to me it seems pretty alright (?), it certainly keeps its speed in turns well. But you're right that at 500 km/h the 262 should out accelerate the propeller driven aircraft, infact it probably should start to slightly do so already in the 450 km/h range. That said I haven't come around to testing the acceleration and climb performance of the 262 side by side with the later props ingame yet.

 

 

Edited by Panthera

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On 6/14/2019 at 4:01 PM, IAmNotARobot said:

We simulated slats exactly that way. Incoming dynamic pressure can be much more expressed then aerodynamic sucktion force and g-force influence, that prevents slats to extend in higher speed.

 

Slat-deployment is a matter of pressure-distribution, which is dependant on AoA primarily and Mach (at transonic speeds).

Differing dynamic pressure just increases the net pressures involved, but not the pressure-distribution (and hence the pressure-ratios acting on the slat @ given AoA).

 

8 hours ago, Holtzauge said:

Was busy doing some IRL flying this weekend (Discus b glider where the controls really stiffen up already at 200 Km/h IAS :happy:)

 

I flew a bT a couple of times and what I didn't like was the lightness of controls/ lack of feedback.

But that's just down to personal taste - the Discus' performance speaks for itself 😎

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8 minutes ago, Panthera said:

Tracked down the following on the Kew archives:

https://discovery.nationalarchives.gov.uk/results/r?_q=Me262

 

 

 

Interesting. There may be something of use there, though a lot of it seems to pre-date the end of the war, and presumably will be based around intelligence reports, rather than actual test data. Sadly, none of it seems to have been digitised, and accordingly isn't available online. It is sometimes possible to get materials copied, but it is expensive if you don't know what the material is likely to contain. I'd have thought that if there were any documents of particular significance, a researcher would quite likely have found them by now - the Me 262 isn't exactly an obscure subject.

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Posted (edited)
6 hours ago, AndyJWest said:

 

Interesting. There may be something of use there, though a lot of it seems to pre-date the end of the war, and presumably will be based around intelligence reports, rather than actual test data. Sadly, none of it seems to have been digitised, and accordingly isn't available online. It is sometimes possible to get materials copied, but it is expensive if you don't know what the material is likely to contain. I'd have thought that if there were any documents of particular significance, a researcher would quite likely have found them by now - the Me 262 isn't exactly an obscure subject.

 

Well Brown already published a summary of his report himself in his book "Wings of the Luftwaffe", so that could explain why no'one else since really have felt the need to basically do a repeat. 

 

But just to reiterate what I said earlier, if the RAF measured stick forces at 2.72 kg pr. G at 645 km/h (i.e. ~19 kg for 6 G & ~21.4 kg for 7 G), then the stick forces in our ingame representation must be way above what it was/is in the real aircraft at that particular speed as it is currently not possible to pull full elevator deflection even at 500 km/h ingame.  

 

In addition to this the trimmable stabilizer doesn't feel anything like the sensitive control surface it was reported to be in real life, requiring (or rather demanding) only small adjustments to trim with speed, where'as ingame it still feels very insensitive and carefree to operate requiring quite a bit of adjustment to trim the aircraft level with speed. 

 

These two issues as well the as the operation of the slats is where I believe the FM can improve. 

 

 

Edited by Panthera

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Go on Andy a quick trip to the archives and copy the lot... nice spot for an afternoon :) They are well set up. Photocopying is stupidly expensive there. I used to regularly visit when in the UK and photographed countless documents there, then put them in PDF when I got home. Sadly I don't get to the UK any more.

 

If you havent been there before you need to do a 15minute CBT course on rules and handling etc. You then get a readers card valid I think for 2 years. You can even pre order files so they are ready for you on arrival. Though typical turn around times are about 15-20mins from ordering a document to it arriving for viewing. The place is a Gold mine.

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