Rudder Control in WoV

[Arrow 83]

I've noticed that when I apply rudder pedals it causes the jets to roll instead of yaw in the correct direction. Whereas I noticed that rudders seem to work correctly in Razbam's Skyraider. I did a search in this forum and the Knowledgebase forum for rudders. I found many topics but the only one that seemed of any use was one referring to the MIG 23. That thread referred to the aircraft_DATA.INI file and the ReverseModelOrientation and RotationAxis settings. So....I extracted the F-4D_DATA.INI file and compared it with the A-1D_DATA.INI file. And low and behold I noticed the following entries were different.

 

A-1D_DATA.INI

 

ModelNodeName=Rudder

ReverseModelOrientation=TRUE

RotationAxis=Z-AXIS

 

F-4D_DATA.INI

 

ModelNodeName=rudder

ReverseModelOrientation=FALSE

 

So noting the difference here it brings up the following questions:

 

1. Are the F-4D_DATA.INI settings incorrect, i.e. should 'ReverseModelOrientation=TRUE' and does a 'RotationAxis=Z-AXIS' entry need to be added?

 

2. Do these edits need to be made for EVERY FREAKING plane in the game!?

Edited October 1, 2008 by Arrow

[Fubar512 1,350]

You use the rudder to roll the F-4.

 

Think of how a rudder on an aircraft like the F-4 is hinged (obviously, on an angle), and picture what the airflow does as it strikes it, and you'll begin to understand why there's a roll component to a rudder input on some aircraft.

[gbnavy61 1]

You use the rudder to roll the F-4.

 

Think of how a rudder on an aircraft like the F-4 is hinged (obviously, on an angle), and picture what the airflow does as it strikes it, and you'll begin to understand why there's a roll component to a rudder input on some aircraft.

 

I don't think the angle of the rudder hinge is any significant portion of the roll. Basic aerodynamics explains why fixed-wing aircraft roll when rudder is applied. This resultant roll is called "proverse roll" (you roll in the direction of yaw). Just remember the lift generated by your wing(s) is controlled by several factors - velocity being one of them.

 

Let's break it down:

1. You're cruising along in your F-4D (or A-1D), fat, dumb and happy.

2. You stomp on the right rudder pedal.

3. Your nose starts to yaw right.

4. Your left wings starts to travel through the air slightly faster than the right wing.

5. Your left wing starts to produce more lift than the right wing.

6. You start to roll to the right.

 

Arrow,

 

The important thing to remember about an F-4 is that it's a big, honking aircraft. If you expect rapid yaw response based on your rudder input, prepare to be disappointed. There's a lot of momentum, plus a few aerodynamic design features, that want to keep you tracking in a straight line. Rudders on jets are useful, but they are not a primary means of getting your nose pointed in a different direction. They're pretty much used for three things airborne: putting the pipper on the bandit, recovering from a spin/departure, and crosswind landings. If you want to bring the nose more than 2 degrees left or right, bank and pull.

 

Now, the A-1D is a different story. It's prop-driven which means the rudder has to give the pilot a lot of authority to counteract torque and other factors associated with a rotating propeller.

 

The moral of the story is: don't expect an F-4 to maneuver like an A-1 - they're different animals. I don't think there's anything wrong with the config.

[gbnavy61 1]

There's also the concepts of stability and maneuverability to consider. In general, the more stability you have, the less maneuverability you have - and vice versa. Obviously, for a fighter there is a strong desire for maneuverability, but the aircraft cannot be completely unstable - it would be too difficult for a pilot to control. For example, looking at the F-8, early models lacked the ventral fins. However, during carrier launches, those F-8s could come off the cat stroke ass-end first because of the poor directional stability - pilots had to eject or die. So, the fins were added to improve the F-8's directional stability.

 

The F-4 has strong positive (wants to return to the starting position) directional stability. You've probably noticed, stomping on the peddals in some jets will get your nose slowly (painfully slowly) tracking in the desired direction. In the F-4, it pretty much slides 2-3 degrees in the desired direction and stops - I've never tried it for more than 10 seconds, but it takes a long time to get the nose yawing around to a new heading - much too long. Trying this in the A-1 will get a better response, although still not as good as rolling in some bank and pulling the nose around in a turn.

 

One way in which the two aircraft differ that affects directional stability is wing design. The Spad is a straight-winged aircraft. The Phantom is a swept-wing design. The Spad's straight wing makes a small contribution to directional stability. When you press the right pedal to yaw the Spad, the left wing goes through the air faster creating more lift, and therefore more drag on that side (production of lift also produces drag), so there is a small increase in drag trying to pull the left wing back to a neutral position. In the F-4, you press on the right pedal and swing the nose to the right. Essentially, the same thing happens as with the straight wing, except that the right wing now experiences greater spanwise flow (flows down the length of the wing from root to tip - producing less lift) and the left wing experiences greater chordwise flow (from leading edge to trailing edge), so there is an even greater amount of lift (and therefore drag) produced by the left wing over the right wing of the F-4. So the overall effect is that the F-4's swept wing creates much more directional stability (resistance to yaw) than the A-1's straight wing.

Edited October 1, 2008 by gbnavy61

[Fubar512 1,350]

The ailerons (spoilers) on an F-4 are essentially useless above 15-18 units of AoA. They are, in fact, more likely to induce adverse yaw at that point, than would the rudder. Once you see 15 units on the gage, you must roll that beast with the rudder.

 

FYI, I've corresponded with two former Phantom drivers, including one that has a MiG-19 kill to his credit.

[gbnavy61 1]

The ailerons (spoilers) on an F-4 are essentially useless above 15-18 units of AoA. They are, in fact, more likely to induce adverse yaw at that point, than would the rudder. Once you see 15 units on the gage, you must roll that beast with the rudder.

 

That is true

[Arrow 83]

I've read what everyone has said here and I can understand why there'd be some roll on aircraft like the F-4. However, the fact is that I get a significant amount of roll and virtually no yaw. Even in the Skyraider where I do get some yaw, the movement is minimal. I really only planned on using rudder control during landing and taxing, but the way it's modelled here I'd be afraid it might cause me to crash. It's true my more recent stick time with a military jet has been in FS2004. but I can say that even for jets that were supposed to have poor yaw rate, the rudder control in FS2004 is worlds away from this sim. The same is true if I contrast the rudder control with F4AF. I don't want to mix apples and oranges amongst sims, but the rudder movement just seems off in this game; almost broken.

Edited October 1, 2008 by Arrow

[commander 0]

the rudder is meant to counter an aerodynamic affect, called adverse yaw, that occurs when a plane turns. AY causes the plane's nose to swinng opposite to the bank, so the rudder is used to bring the nose back into the turn.

[Fubar512 1,350]

Again, look at the rudder on the F-4. It is canted at an angle. When you push on the rudder pedal(s), and induce a movement, the rudder's base on that bird swings out and downward. As the airflow strikes it, it does not do so perpendicularly. The bulk of the airflow is traveling upwards from the bottom of that control surface. This effect increases with AoA, so that only the upper portion of that control surface is rendered effective. That being the case, the majority of the air flow that's diverted by the rudder is well above the roll center of the aircraft. Guess what happens then?

[Fubar512 1,350]

Further reading; This webpage just touches on the basics of the F-4's handling charecteristics, though the author mistakenly used degrees of AoA, when in truth, those values are in Units of AoA: http://www.geocities.com/cap17.geo/FlightPerformance.html

[gbnavy61 1]

Arrow,

 

Are you using rudder pedals, or the keyboard or joystick? The way the rudders are set up in this game is there is a slight delay before you get to full rudder deflection. If you're using the keyboard, all you can do is tap the key to get small amounts of rudder - not the best way to do it. If you have pedals or a joystick w/ twist (which I personally can't stand) you can map the rudder there for finer control.

 

FS9 or any of those have the option of the repeat function where your rudder inputs will stay in after you stop pressing the key. WOV does not have this function.

 

Yes, the MSFS series gives better response to rudder inputs than this series, although I'm not sure which is more accurate. I've found the rudder control in WO* to be more than adequate for taxiing, and I hardly ever use rudder on landing - not until the wheels are on the deck. If I'm not lined up on the runway, I use angle of bank to fix that.

 

Either way, airplanes aren't designed to turn using the rudder. Like commander said, rudder is used to coordinate the turn.

[Arrow 83]

Arrow,

 

Are you using rudder pedals, or the keyboard or joystick?

 

I'm using CH Products Pro Pedals, as well one of my joysticks -Logitech Wingman Force- has a twist rudder. Just of of curiosity I tried the Logi sticks twist rudder and got the same result.