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Questions about Aerodynamic Model


IIIJG52_Otto_

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In DCS the Fw-190 D9has not modeled the aerodynamic effect of "prop-wash" in the tail control surfaces, and I think that despite what was announced at the beginning, for the P-51D also has incorrectly.

 

The blue lines of the picture should reach the tail

1267628_10202254810033953_1152722313_o.jpg

 

the effectiveness of the rudder, in the DCS-Dora, is obtained only when the plane is almost in flight. The air-flow that the propeller throws on the tail is not aerodynamically modeled. The plane takes off skidding, and out of control in yaw axis, until it iairborne. (minute 0:38 in the video)

THIS IS A BUG !!

..Although here we have very good pilots, and they can take off without rudder :pilotfly:

 


Edited by III/JG52_Otto_+
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Great post Otto as an experienced pilot I agree completely. There probably should be sufficient airspeed and prop wash for relatively easy control of yaw and roll at around 40mph /100kph, just an educated guess. Other forces acting on the aircraft seem appropriate, but without flight controls having some effect at relatively low speed and without any apparent aerodynamic stability developing well before takeoff speed....things are only very narrowly managed... there should be a lot more room for control surfaces to counter yaw and roll before loss of control....

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In DCS the Fw-190 D9has not modeled the aerodynamic effect of "prop-wash" in the tail control surfaces, and I think that despite what was announced at the beginning, for the P-51D also has incorrectly.

 

The blue lines of the picture should reach the tail

 

 

the effectiveness of the rudder, in the DCS-Dora, is obtained only when the plane is almost in flight. The air-flow that the propeller throws on the tail is not aerodynamically modeled. The plane takes off skidding, and out of control in yaw axis, until it iairborne. (minute 0:38 in the video)

THIS IS A BUG !!

..Although here we have very good pilots, and they can take off without rudder

 

 

 

great post only, if the picture shows the effect with full thrust provided by the prop.

 

Which we do not know. So this is an assumption in the first place, no evidence given.

 

But yes, it would be nice if someone enlightens us if the effect would reach the enpennage of the airframe.


Edited by I./ZG15_FALKE
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In DCS the Fw-190 D9has not modeled the aerodynamic effect of "prop-wash" in the tail control surfaces, and I think that despite what was announced at the beginning, for the P-51D also has incorrectly.

 

The blue lines of the picture should reach the tail

1267628_10202254810033953_1152722313_o.jpg

 

the effectiveness of the rudder, in the DCS-Dora, is obtained only when the plane is almost in flight. The air-flow that the propeller throws on the tail is not aerodynamically modeled. The plane takes off skidding, and out of control in yaw axis, until it iairborne. (minute 0:38 in the video)

THIS IS A BUG !!

..Although here we have very good pilots, and they can take off without rudder :pilotfly:

 

 

Hi Otto welcom to the forum. This thread is not to report bugs but its a tracking thread so you can see what bugs are reported and wich bugs have been fixed.

 

If you think the aeromodel is wrong then please post a seperate thread dedicated to this subject. As soon as its picked up or reported ill add it to the list in this thread so you can see it.

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great post only, if the picture shows the effect with full thrust provided by the prop.

 

Which we do not know. So this is an assumption in the first place, no evidence given.

 

But yes, it would be nice if someone enlightens us if the effect would reach the enpennage of the airframe.

 

Full Thrust isn't necessary or do you really think you need always full thrust to steer your plane on ground with the rudder or only at full thrust there is a effect by the prop air on the rudder?

Not really?!

As you can see if you watch some AI Planes at the taxi procedure, the FW is bumping and steers like the TRON Bikes. The rear wheel is bumbing and moves the whole time in opposite directions.

The FW190 D-9 moves not the same way as all other Planes in DCS. Looks more like a Rodeo.

The physics are clearly broken.

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  • ED Team
In DCS the Fw-190 D9has not modeled the aerodynamic effect of "prop-wash" in the tail control surfaces, and I think that despite what was announced at the beginning, for the P-51D also has incorrectly.

 

The blue lines of the picture should reach the tail

1267628_10202254810033953_1152722313_o.jpg

 

the effectiveness of the rudder, in the DCS-Dora, is obtained only when the plane is almost in flight. The air-flow that the propeller throws on the tail is not aerodynamically modeled. The plane takes off skidding, and out of control in yaw axis, until it iairborne. (minute 0:38 in the video)

THIS IS A BUG !!

..Although here we have very good pilots, and they can take off without rudder :pilotfly:

 

 

Kakie vashi dokazatelstva?

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Full Thrust isn't necessary or do you really think you need always full thrust to steer your plane on ground with the rudder or only at full thrust there is a effect by the prop air on the rudder?

Not really?!

As you can see if you watch some AI Planes at the taxi procedure, the FW is bumping and steers like the TRON Bikes. The rear wheel is bumbing and moves the whole time in opposite directions.

The FW190 D-9 moves not the same way as all other Planes in DCS. Looks more like a Rodeo.

The physics are clearly broken.

 

 

I think most of the things you listed there are more likely related to pilot error than anything else ;)

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Are you sure it's not reaching the tail? I can lift the P-51's tail at a standstill. I haven't tried for the Fw-190, but the couple of takeoff attempts that I made didn't make me think the rudder wasn't working. I don't know if it's too strong or too weak, but I'm sure it's working.

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Are you sure it's not reaching the tail? I can lift the P-51's tail at a standstill. I haven't tried for the Fw-190, but the couple of takeoff attempts that I made didn't make me think the rudder wasn't working. I don't know if it's too strong or too weak, but I'm sure it's working.

 

Yes, this is true, I was testing overheating on the ground, and could only ramp up the motor so much before the plane's tail would lift... the lines in the graphics dont show the reach of the air, only the direction... the OP is mistaken.

 

I didnt think to try the rudder while my tail lifted, that would be telling... if there was enough to lift the aircraft there should be enough to turn it as well...


Edited by NineLine

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cant say much here, but i have to say, that after some more takeoffs i can hold the 190 straight on the runway, and the rudders are doing a good job there. (auto rudder unchecked, set to 0%, just in case someone questions)

 

but i guess yo-yo could help there? in english this time please :D

 

regards,

RR

 

PS:

otto, i saw you yesterday on the VA server, so just a side note:

IF you have auto rudder on and 100%, this will NOT work on the server. there you have to do it all manualy atm ;)

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Great post Otto as an experienced pilot I agree completely. There probably should be sufficient airspeed and prop wash for relatively easy control of yaw and roll at around 40mph /100kph, just an educated guess. Other forces acting on the aircraft seem appropriate, but without flight controls having some effect at relatively low speed and without any apparent aerodynamic stability developing well before takeoff speed....things are only very narrowly managed... there should be a lot more room for control surfaces to counter yaw and roll before loss of control....

 

 

Have you flown anything remotely like a Fw 190D-9 in real life? I have driven a Ford Escape, so I should know how a race care should handle on the track at 200mph ;)

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Have you flown anything remotely like a Fw 190D-9 in real life? I have driven a Ford Escape, so I should know how a race care should handle on the track at 200mph ;)

 

That was some kind of troll assumption. You are comparing "churras con merinas", like we say in Spain. All tail draggers "fly" on ground the same way, so if you flyed a real taildragger you know, in general, how the feel is even in a simulator. :book:

 

Cheers & Cheese

 

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That was some kind of troll assumption. You are comparing "churras con merinas", like we say in Spain. All tail draggers "fly" on ground the same way, so if you flyed a real taildragger you know, in general, how the feel is even in a simulator. :book:

 

Cheers & Cheese

 

Ballenato

 

Well I disagree.... There are many differences in the P-51 and the Dora, I am sure whatever he has flown has even more differences... sure, there would be some similarities... but you over generalize thinking that you should be able to fly one plane, and that qualifies you for all aircraft... comes down to practice... and people are not giving themselves enough time to become comfortable with the 190, they assume it should be the same... if its the same, why bother, just pump out a bunch of models and use the P-51 FM for everything...

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Well,

 

my experience from using the p51d, and now this Fw190 D9 tells me that CERTAINLY PROPWASH EFFECTS ARE BEING MODELED!!!

 

To start with, the tail wheel on the p51d and the Dora are of completely different types, and indeed IRL toe braking is used during taxi, in a fw190, as you can easily see described in many documents.

 

Then, I do use rudder at taxi speed, and it certainly is effective, although not sufficient to steer the aircraft when you have to turn into a taxiway.

 

Finally, probably one of the best tests you can do to see up to what level of detail this "slipstream" modeling goes, pick a x-wind component of 10m/s ( or more, at you own risk... ) and tell me what happened during the first stages of your takeoff run.... Go figure why... and you'll see what I mean, or, just read in this thread

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Well I disagree.... There are many differences in the P-51 and the Dora, I am sure whatever he has flown has even more differences... sure, there would be some similarities... but you over generalize thinking that you should be able to fly one plane, and that qualifies you for all aircraft... comes down to practice... and people are not giving themselves enough time to become comfortable with the 190, they assume it should be the same... if its the same, why bother, just pump out a bunch of models and use the P-51 FM for everything...

 

No body is talking or arguing about fly feeling but ground handling..please read some and enlighten yourself.

 

http://www.taildraggers.com/Documentation.aspx

 

Cheers & Cheese

 

Ballenato

www.jagdgeschwader52.net

 

[sIGPIC][/sIGPIC]

 

... and make mistakes until getting it right, there is no clear line between acquiring

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Just did two tests from standstill in Dora:

 

Test 1: Full thrust with brakes on, released brakes when tail starts to lift then full rudder left.

 

Result: A complete 180 after 10 m run no damage :smilewink:

 

Test 2: Full thrust with brakes on, released brakes when tail starts to lift then full rudder right.

 

Result: Quite a bit slower due to the slipstream rotation which the rudder has to overcome but still a 180 to the right albeit ending up nose down with ruined prop after a short run this time.

 

Conclusion: Since forward speed basically zero, rudder force must be due to propwash.

 

So I don't know what the coloured streamers in the OP are supposed to show but there is certainly propwash modelled and I for one can't see the problem......

 

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No body is talking or arguing about fly feeling but ground handling..please read some and enlighten yourself.

 

http://www.taildraggers.com/Documentation.aspx

 

Cheers & Cheese

 

Ballenato

 

 

From the link you posted:

 

Takeoff

 

The next difference you will notice comes during takeoff. With a tricycle gear airplane, you accelerate down the runway, the airplane pretty much rolling straight on its own, until you reach a desired speed, at which time you simply pull back on the wheel and lift off. Takeoffs in a taildragger require a lot more work. Predominantly, right rudder will be required to keep the airplane rolling straight down the runway, but constant rudder corrections are necessary to keep it rolling absolutely straight. With the tailwheel on the ground, most taildraggers are rolling down the runway right at the stall angle of attack. This is by design for landing purposes. The normal takeoff procedure is to raise the tail just a little to the proper angle of attack for the airplane to fly itself off the ground. When the tail comes up, you lose the traction of the tailwheel, so a little more right rudder is required to keep it going straight. Also, there is a law of physics that says when the plane of a gyro is tilted, it reacts with an opposite force 90 degrees in the direction of rotation. Well, it turns out that the propeller is a pretty good gyro. When the tail comes up, you are tilting the plane of the propeller. The force you are applying is the equivalent of pushing at the top of the propeller arc from behind. Since the propeller is rotating clockwise when viewed from behind, the gyroscopic reaction comes as if it were pushing on the airplane's right side of the propeller arc. This tends to turn the airplane to its left while the tail is actually moving up. So, while the tail is moving up, an extra dose of right rudder is required. A good taildragger pilot leads with a little extra right rudder an instant before the tail starts up to keep the nose aligned perfectly straight, rather than waiting for it to start left and then apply the correction. Also know that the more horsepower the engine has, the stronger this gyroscopic reaction is, as well as torque, so more right rudder will be required. In some really powerful airplanes, you would not have enough rudder to counteract these forces, so power is carefully applied and increased thought the takeoff roll so you don't run out of rudder. Once you get the tail up and stopped at the desired pitch attitude, you're in pretty good shape. The airplane is picking up significant speed now, so the rudder is becoming very effective. The P-factor is also reduced with your now lower angle of attack. You still have to pay full attention straight ahead and use the rudders to keep the airplane going straight, especially in a crosswind. Soon, the airplane lifts itself gracefully off the ground. Many people get the tail too high on the takeoff roll and then pull back on the yoke to lift off. It's better to learn the right attitude for your airplane so it flies itself off under normal conditions. This allows you to look straight down the runway and ignore the airspeed indicator so you can keep the airplane straight.

 

 

Sums up exactly what I am experiencing with both prop modules.

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I dont need to read that.. I have quality flight simulations of two aircraft I can try and see the differences in them, both which have been flown by pilots that flew these actual aircraft... I'm good thanks...

 

These simulated prop models can't be beat overall for flight fidelity, IMO, but they are still approximations and fidelity varies in quality in different aspects of the sim. I feel like I'm flying a Dora when airborne and flight forces are reasonable and believable. Taxiing control at low speed seems reasonable (not sure if it's accurate, but it is reasonable).

 

Aircraft control between less than takeoff speed and taxi speed however is poor, seemingly a result of 'slipstream' along the longitudinal axis not having a proper effect on control surfaces and the stabilizing force of the vertical tail and fuselage... so a degree of pilot control over other forces acting on the aircraft is in large part missing. Yes you can takeoff following a very narrow margin of control, and it looks and 'feels' great until you have a small deviation that can't be countered. The Mustang feels very realistic on takeoff roll through liftoff, based on pilots reports, flight manual advice etc it's apparent that real recent Mustang drivers gave input..... but they don't test the limits of controllability on a takeoff roll or don't know it, and obviously didn't give that feedback. The force calculations outside of that narrow band of ideal control don't inform the pilots where reasonable limits of control are on the takeoff run or landing roll, IMO.

 

I have no trail dragger experience, just single engine recip, twin turboprop, military jet trainers and heavy jets. An analogy: if you were zipping around a corner in your Ford Focus and a wheel came off, would you notice it? If you were zipping around a racetrack at high speed and lost a wheel from your race car would you notice it? There is something missing, the same thing, and it's fundamental to basic forces in effect between two four wheeled cars going around a corner.... it's just a matter of degree.

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No body is talking or arguing about fly feeling but ground handling..please read some and enlighten yourself.

 

http://www.taildraggers.com/Documentation.aspx

 

Cheers & Cheese

 

Ballenato

 

I'm with Ballenato here...... the effect of 'flying' on the ground at appropriate speeds feels underrepresented.... I don't have a problem with other forces in effect, it's just that they easily overwhelm control authority, to a degree that is inconsistent with ease of takeoff and landing in this aircraft as noted by test pilots.

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  • ED Team
I'm with Ballenato here...... the effect of 'flying' on the ground at appropriate speeds feels underrepresented.... I don't have a problem with other forces in effect, it's just that they easily overwhelm control authority, to a degree that is inconsistent with ease of takeoff and landing in this aircraft as noted by test pilots.

 

But is that the flight model or is that those crappy plastic controllers we have sitting on our desks, I would imagine this is one of the most delicate moments in a flight... subtle inputs are probably called for, you dont always get those with even the highest quality sticks... especially when we start talking the different in length of our flight sticks compared to the actual ones... remember these sims are done with the real thing in mind... not my stubby X55....

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Something is off and while I am no engineer I just feel its due to not enough energy bleed off with no power.When my engine cuts out I expect the plane to drop like a rock but it instead just floats on and on.This is ok to live with as I try not to bust my engine BUT it in turn is causing my landings to feel off.With power off and landing I seem to float forever over the runway and find I need to pull too much on the stick which is causing three pointer landings.If I want to do a 3 pointer I would like to be able to initiate it but instead I find that I NEED to pull too much elevator to bleed off speed.


Edited by wolfstriked

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But is that the flight model or is that those crappy plastic controllers we have sitting on our desks, I would imagine this is one of the most delicate moments in a flight... subtle inputs are probably called for, you dont always get those with even the highest quality sticks... especially when we start talking the different in length of our flight sticks compared to the actual ones... remember these sims are done with the real thing in mind... not my stubby X55....

 

I think it's the only gross shortcoming in the model..... takeoff should and is a delicate thing with some very dark corners that will kill you quickly if you don't know what to expect.... it's just the observed attitude deviations on takeoff roll are too small when loss of control occurs...room for error is too small. It feels as if aerodynamic stability which should start to occur at relatively low speed is missing... as well as flight control effectivity.

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I'm with Ballenato here...... the effect of 'flying' on the ground at appropriate speeds feels underrepresented.... I don't have a problem with other forces in effect, it's just that they easily overwhelm control authority, to a degree that is inconsistent with ease of takeoff and landing in this aircraft as noted by test pilots.

 

One thing I have noticed in so many flight sims is that the wheels dont seem to model grip sideways properly.So many sims you see have planes taking off with huge sideslips down runway.If just s bit more lateral stability was added to the front wheels,like the amount the rear wheel has when locked in the Dora,then I think takeoffs would look slightly more realistic.

"Its easy,place the pipper on target and bombs away." :pilotfly:

 

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