Do all fs9 planes need rudder in turns?

[Guest aca_dia]

Well worded. The reality is that aerodynamics is much too complex to assume a single rule works for all flight situations. As far as rudder and steep turns go that really depends on the aircraft as well. A PA44 (Seminole) will very typically be uncoordinated through a steep turn (even up to commercial tolerances of 50+- degrees of bank) if no rudder is maintained through the turn. I use this aircraft as an example because that is what I was most recently doing steep turns in. Even a 172 can require a fair amount of rudder during a 45-degree steep turn (had a student demonstrating this today). Partly this is because rarely does anyone maintain a perfect angle of bank through an extended turn so turning forces are constantly changing a little.No argument though. The majority of rudder used for turning is used for initiation and rollout. Bringing this back to the initial post I have found that a properly configured Fs9 with a good aircraft model models rudder use fairly well. It is not perfect and it will never be since the real world isn

[lcseale53 0]

A great deal depends on the airplane, but first let's simplify this thing a bit and reduce it to some basic trigonometry. The lift vector is the vertical component of a two-part resultant vector (the other being the horizontal component), which acts perpendicular to the wing. When the wing is level the lift vector is vertical with no horizontal component (we'll omit the effects of vortices, p-factor, etc. for this argument). When the wing banks (tilts) the 'resultant' vector tilts with it. The vector now has two components - one vertical and the other lateral. The vertical component, which is the portion 'supporting' the aircraft is now reduced in magnitude (in essence it's the 'adjacent' side of a right triangle with the 'resultant' vector as the hypotenuse), thus, an angle of attack increase is necessary to maintain altitude. So you apply back pressure. The horizontal component of the vector, while in the bank attitude(described as the 'opposite' side of our right triangle is applying a lateral force to the aircraft, inducing a 'slide' or skid in the direction of the component vector. The aircraft is indeed changing direction, but not in a coordinated fashion. Inducing a coordinated turn at this point requires one of two things (keeping it simple) - rudder input to align the tail with the nose throughout this direction change, or something inducing drag on the 'inside' wing causing a slight decrease in airspeed (at that inside wing), resulting in a slight rotational (yaw) effect to compliment the bank induced skid as the turn is initiated and maintained.This induced drag may be created by the application of differential aileron movement. In this case the aileron travel upward is greater than the travel downward. The aileron on the outside of a turn is down, relative to the wing, and the inside is deflected upward. The inside/upward deflection is greater than the outside/downward deflection, the result being more drag on the lowered wing, and less need for rudder input as the turn is initiated and maintained.How does that help once the bank is established and the ailerons are neutralized - in typical bank attitudes a slight aileron input is necessary to counter the inherent stability created by dihedral, airfoil, etc. That is until a critical angle is established, at which point the bank may tend to tighten.I own a Cessna 206, which uses differential aileron travel, and most flying can be done reasonably coordinated with both feet on the floor, but I also have a Cessna 120, with essentially no differential aileron travel - as well as a lower wing loading...different airfoil...etc., and you WILL keep both feet firmly planted on the rudder pedals both into and throughout any turn. The physics are really pretty simple, rudder (or something inducing drag to the inside of the turn) is necessary to keep a turn coordinated (ball centered and coffee in cup). In theory the above generally applies to all aircraft, but very high performance aircraft have different thresholds with respect to just about everything noted above.Just my training and experience - yours may vary.Leon

[Guest aca_dia]

Good point bringing up differential ailerons.

[Guest Ron Freimuth]

>...........>This induced drag may be created by the application of>differential aileron movement. In this case the aileron>travel upward is greater than the travel downward. The>aileron on the outside of a turn is down, relative to the>wing, and the inside is deflected upward. The inside/upward>deflection is greater than the outside/downward deflection,>the result being more drag on the lowered wing, and less need>for rudder input as the turn is initiated and maintained.>...........>How does that help once the bank is established and the>ailerons are neutralized - in typical bank attitudes a slight>aileron input is necessary to counter the inherent stability>created by dihedral, airfoil, etc. That is until a critical>angle is established, at which point the bank may tend to>tighten.>Leon 'Adverse Yaw' (due to ailerons) is generally small in most AC (designed since 1930 or so). Cn_dp, Yaw Moment due to Roll Rate, is intrinsic to all conventional aircraft. When one starts a CCW roll to turn left the AoA over the left wing is less than that over the right. So, the right wing generates more induced drag. Yawing the AC to the right. OTOH, once the Roll is no longer changing, the AoA's, thus Induced Drags are much closer. It's the Roll Rate, not the Roll angle that has the greatest effect on unwanted Yaw. One can see this by watching the Ball. There is also Cl_dr, Roll Momement due to Yaw Rate. Note if one yaws an AC with the Rudder one wing moves forward, the other back -- relative to the AC's center. The side moving forward has more lift, the side moving back has less. So, one gets a Roll moment when Yaw is changing. There are also Roll and Yaw moments that don't depend on rates. Note a rudder above the centerline of an AC creates a twisting (roll) moment whenever it's deflected. If the rudder were below the centerline the roll would be in the opposite direction. Yaw and Roll MoI's also add to dynamic effects. The 'coupled roll-yaw MoI' is also undesirable, but usually of neglible value. It is more significant in an AC such as the 747 that can store fuel in the vertical fin. Vertical CG relative to vertical Center of Lift is also significant. A Yaw Damper is a mechanical feed back system that works to minimize Yaw. Thus, it pretty much coordinates the AC for the pilot. One reason 'no feet' works in flying big jets. However, MSFS has NEVER had a real Yaw Damper. The MS Airheads don't seem to be capable of programming this simple device. RAF

[Guest fl390]

I'll go back to ball watching during turns in fs9, hopefully I can play with the settings and try different planes until at least a standard rate turn doesn't need nearly as much rudder when established as it does at start and end!

[Guest paddy]

Now you see how far the theory of making a turn in an aircraft can be digged out! Remember "to step on the ball" and use a stopwatch to check your standard turn of 180 degrees per minute....Paddy.

[Guest Ron Freimuth]

>I'll go back to ball watching during turns in fs9, hopefully>I can play with the settings and try different planes until at>least a standard rate turn doesn't need nearly as much rudder>when established as it does at start and end! When I was checking AIR files for Roll-Yaw effects I found things worked just as described in Aired: The Ball moved to one side when there was a Roll Rate, but tended to center once the wings were at a steady bank. I always keep an eye on the coordination Ball. I did even when flying real SEL's. One feels the forces in a real AC, but may need to watch the instruments more in a simulator. Regardless, ones senses can get confused, so it's almost always better to believe the instruments than ones sense of rotation, slip, etc. If ones vacuum pump fails, then he had better not believe the 'artificial horizon'. That's when he should use the Turn Indicator Needle. It's electrically powered, so still works with a vacuum failure. Careful tests in MSFS show that when the needle indicates a 2 minute turn, it takes just 1 minute to turn 180 degrees. RAF

[lcseale53 0]

Ron (BTW, thanks for the input),Absolutely, when you disturb a balanced aerodynamic system, you induce couples all over the place. The effect you noted above is very pronounced in the 120. Unlike the 206, which allows you to fly rather well with your feet on the floor, - the 120 allows you to fly with your hands in your lap (assuming calm air). The roll response with the application of rudder is sufficient (albeit in gentle amounts) to establish a nicely/nearly coordinated turn with neutral ailerons (as known by those of you who have flown single channel - rudder only - R/C models). Concurrent with a wing that exhibits nice roll couple, as you previously noted, is the presence of adverse yaw with the application of aileron (1946 vintage with a constant chord non-tapered lightly loaded wing...and aileron travel 20 degrees both up and down). With respect to the 206, adverse yaw is pretty well countered by the differential aileron travel...21 degrees up and 14 degrees down. And at the higher airspeeds and higher wing loading (among a host of other differences), the 206 does not exhibit the same degree of roll couple. Anyway, I just wanted to acknowledge your quote above, having spent many hours kicking the wings back level and/or following a heading with rudder alone in the grand ole 120.Thanks,Leon