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Serbian_Pilot

Steep turns in general aviation

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Hi guys.

 

I have a ppl license almost 25 years now, just to clarify my aviation education.

 

I have a Aerosoft Diamond Katana 4x , general aviation plane which has, in my opinion, best in depth systems simulation for such a little plane. It is a PMDG in general aviation in terms of graphich and systems simulated.

 

Many FSX user consider it to be among best aircrafts ever released for FSX. It is a marvel in the payware section of FSX, no doubt.

 

BUT, yaw axe and rudder behaviour is what concerns me about this aircraft.

 

Every real life pilot must perfect steep turns, in order to get Private Pilot license, everybody knew that. It is a moderately hard maneuver but it IT IS NOT IMPOSIBLE. It is a hard but routine maneuver for ppl pilot.

 

But in 99% of payware planes (general aviation) yaw axe is very, very poorly modeled.

 

I cant get Katana 4X to do a COORDINATED steep turn at 45 degrees. I tried so many times and inclinometer wobbles all around. I calibrated yoke with latest and registered FSUIPC, set sensitivity in slope function of this software, set dead zones etc. I tried everything.

 

 

Any oppinions?

 

Thanks in advance !!!

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When in a steep turn (maximum 45[PPL]-60[CPL] degrees) there should be enough g-loading to nearly or completely center the ball. Rudder input should be at a minimum, using only bank (+/- 5 degrees, never exceeding maximum if you're using the PTS) and some pitch to maintain altitude.

 

In the sim, this can be much more difficult. That seat of the pants feeling is gone and you're effectively over relying on the instruments. Sounds to me like you're just having issues adjusting to the sim environment and the sensitive nature of the controls. Would that be accurate?

 

I wonder what makes you say most aircraft's yaw behavior is incorrect? Unless near the edge of the flight envelope or trying slips, this behavior is okay. That wouldn't be much of a factor in the above maneuver, anyway.


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Please excuse me for my english language :mellow:

 

I agree that saying that yaw axe is a very porly implemented is a bit overstatement. But forgive me, I was a bit sad and frustrated besause I could not do a steep turn with a inclinometer ball rougly in the cage.

When Aerosoft Katana (and many other planes which I own and which came from representative software developers like Aerosoft, Flight1 etc...) goes over 30 degree of bank, like 45, ball moves a lot and fast. I try to coordinate with a rudder pedals, I am constantly looking at a inclinometer and with my peripheral vision on to the horisont outside the virtual cockpit, but that doesnt help.

 

I know from my RL experience that when you establish a bank, and when you return yoke to neutral, ball should be roughly in the middle, you only make small corrections to bank angle like you said to keep est5ablished bank angle and add back pressure.

 

When ailerons are neutralised, adwerse yaw is greatly reduced.

I agree with you that seat of the pants feeling is gone, but in the simulator you also have a visual reference to the horison, you watch VSI needle for altitude etc

 

It is a CONSTANT and I mean CONSTANT struggle to keep a inclinometers ball in the cage. It is so woobly that I justifiably think it is poor implemented.

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It isn't real airplanes in FSX, folks! Aces Studios left out entire basic aspects of true aerodynamics from the equations to develop a flight model. Therefore, everything is to a certain degree a compromise. To achieve realism in one area you have to give it up in another. Someone who develops flight models, such as Bernt Stolle, can go into much more detail than I can, but in working with him to test and evaluate FSX aircraft, it was often very frustrating how one had to decide what area to compromise in order to achieve higher fidelity in other areas.

 

Just have to accept the truth that FSX is nice in many areas, but deliberately compromised. Just one example: no method to replicate how prop wash over a wing adds lift (which is a factor in single engine operations in a piston twin with the two engines mounted on the wings). If you have no mathematical option to model it, then you are forced to use another option, and using that option will weaken the flight dynamics in other areas.

 

Ken

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I realize that, Ken, and thank you for your answer. but there is a flight dynamics modeling minimum that must be fulfilled.

 

Aerodynamics is a complex science, but it is deterministic, not indeterministic. It is not a some sort of unexplained mistery. Good aircraft developers like A2A already do some advanced flight dynamics in their planes. Software that represents actual airplane in a simulator, must at least satisfy

things like performance tables when climbing , descending, taking off etc.

 

these are my humble observations, and I hope they will tell their opinions.

 

it's a shamethat this subject is greatly neglected after 20 years of development of flight simulators.

 

please sory for the red letters, but I want to make a valid point

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It isn't real airplanes in FSX, folks! Aces Studios left out entire basic aspects of true aerodynamics from the equations to develop a flight model. Therefore, everything is to a certain degree a compromise. To achieve realism in one area you have to give it up in another. Someone who develops flight models, such as Bernt Stolle, can go into much more detail than I can, but in working with him to test and evaluate FSX aircraft, it was often very frustrating how one had to decide what area to compromise in order to achieve higher fidelity in other areas.

 

Just have to accept the truth that FSX is nice in many areas, but deliberately compromised. Just one example: no method to replicate how prop wash over a wing adds lift (which is a factor in single engine operations in a piston twin with the two engines mounted on the wings). If you have no mathematical option to model it, then you are forced to use another option, and using that option will weaken the flight dynamics in other areas.

 

Ken

 

I'm aware that these aren't "real airplanes", my friend! :rolleyes: But steep turns in most of these sim aircraft work similarly to a real one.

 

To stay on topic, I'll try a steep turn in the Katana 4x (as I do own it). I'll report back once I do in a few minutes. I'll have to reinstall from Simmarket...


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Alright, I just took off and climbed to 1,000AGL in the Katana 4x. I set power for roughly Va and briskly entered a 45 degree bank with enough back pressure to keep the the nose "on the horizon". I did notice the ball honed towards the center (accurately), but turbulence (AS2012) did make it bounce outside of the center regularly.

 

I then tried a 60 degree bank steep turn. With a small input of left rudder, the ball was perfectly centered excluding turbulence related movements. Altitude control is a bear in this aircraft, but nothing seems overly inaccurate. Overly sensitive, maybe, but the Diamond Katanas feel that way in real life. Very light on the controls. Having a yoke instead of my joystick doesn't help this sensitivity.


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Zachary Waddell -- Caravan Driver --

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BTW, RealAir's airplanes like the Scout and Duke do require good rudder usage along with the freely available 172 air file. And yes, I'm not as impressed with the Katana 4X as many others are, either.

 

For whatever reason rudder usage seems under-used in simulated airplanes in many sims -- it's one of my issues with XPlane's planes, too -- after doing a 60-degree bank steep turn with no rudder.

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I realize that, Ken, and thank you for your answer. but there is a flight dynamics modeling minimum that must be fulfilled.

 

Aerodynamics is a complex science, but it is deterministic, not indeterministic. It is not a some sort of unexplained mistery. Good aircraft developers like A2A already do some advanced flight dynamics in their planes. Software that represents actual airplane in a simulator, must at least satisfy

things like performance tables when climbing , descending, taking off etc.

 

these are my humble observations, and I hope they will tell their opinions.

 

it's a shamethat this subject is greatly neglected after 20 years of development of flight simulators.

 

please sory for the red letters, but I want to make a valid point

 

There is a lot of difference in how close an FDE can come depending upon the kind of maneuver performed. Simple climbs and speeds in cruise are fairly easy to get accurate. But, when you add in G-loads and have to account for induced and parasitic drag values, then the situation becomes more complex. I have never once seen anyone nail an FSX airplane against the real thing. There are always compromises, and when you are experienced with the actual aircraft, the differences can be significant. I've been blessed to work closely with some of the very best in the black arts (Jerry Beckwith and Bernt Stolle come to mind immediately) and they have helped expand my appreciation for how limited FSX is in terms of giving the FDE developers a clear path to achieve nuances.

 

I have always noticed that g-loaded turns (such as required 2G's for a 60 bank level turn) are never accurate. In fact, I have found that trying to perform maneuvers like chandelles, lazy eights, and step turns are more likely to cause negative transfer than they are to approach realism. If you need to know the precise reason for this, you will need to speak with the experts in FDE development. These experts have spent the time to explain a few reasons with me, but frankly the information was "above my paygrade!"

 

That was my point.

 

Ken

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Chandelles,lazy eights for sure don't work. However, I found fs useful when I got my commercial years ago by practicing expected or imagined results on the sim and ignoring the actual sim results.


Geofa

WANTED DEAD OR ALIVE-the best Flight Sim!

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@ Ken

 

I did not know for your cooperation with FDE gurus like Beckwith and Stolle. Great man, I admire their work in that sim department. It seems to me that every flight manuever that is non standard as to speak, gives sometimes contradictory, opposite result in FSX. Movement of the inclinometer is sometimes REVERSED, totally opposed to real thing. That is a big problem!

 

@ Geofa

Sir, I see that you have big RL flight experience. It would be great if you can indicate to us where you have noticed that the simulation of flight dynamics in FSX is particularly compromised ?

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I always found the rudder action strange, since its impossible to KEEP it yawning, it seems to induce a yaw, then returning on its own.

But it MUST be in the FDE, since some plane makers got it right!

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It isn't real airplanes in FSX, folks! Aces Studios left out entire basic aspects of true aerodynamics from the equations to develop a flight model.

 

Yup.. but with its limitiations, FSX is generally good.

 

One of my biggest nags about FSX is, when flying twin GA's and you drop the gear, it feels like you got the flaps out and it starts climbing.

 

The procedure I was taught in flying the Seneca..When I am on approach and I come to FAF is, to drop the gear and I do nothing else and it would descend at 3degee (ILS). But I can never get this to work in FSX.

 

 

Manny


Manny

Beta tester for SIMStarter 

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Interesting thread. When I compare my R/L flight experience in a C172, most GA aircraft have an issue with pitch attitude. In the C172 that I have flown, the pitch attitude is the most stable if trimmed correctly, and while additional pitch input is required in turns (especially steep ones), it's not required as early in the turn and as much in the real thing as in FSX. Also a similar comment when it comes to power changes- the nose responds almost immediately to seek the speed that the aircraft is trimmed to. Of course, if the a/c isn't trimmed, all bets are off.

 

It would be great to see the same thing in FSX, I think of this every time I make a turn. Even at standard rate, the VSI goes more negative and the IAS increases almost immediately in FSX, which is not my R/L experience. There's a reason why we use standard rate turns in instrument flying.

 

I assume this is all related to the above topic of trade-offs being made with tables and programming which I don't understand, but it sure would be cool to fix it.

 

Thanks, Bruce.


ASEL, Instrument.

KBJC, Colorado.

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@ Ken

 

I did not know for your cooperation with FDE gurus like Beckwith and Stolle. Great man, I admire their work in that sim department. It seems to me that every flight manuever that is non standard as to speak, gives sometimes contradictory, opposite result in FSX. Movement of the inclinometer is sometimes REVERSED, totally opposed to real thing. That is a big problem!

 

@ Geofa

Sir, I see that you have big RL flight experience. It would be great if you can indicate to us where you have noticed that the simulation of flight dynamics in FSX is particularly compromised ?

 

I haven't been doing much fsx'ing as of late so I'll have to check back when I get some time in a few days.

Off the top of my head,I recall complaints of not being able to do a timed 2 minute standard rate turn


Geofa

WANTED DEAD OR ALIVE-the best Flight Sim!

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