Well i don't mean for this to come across bad in anyway but this is from my dads m8 who fly's Ryanair 737-800.He Quotes "What your referring to are the spoilers which are basically speed brakes and are operated in both air and on the ground.The flight spoilers are speedbrakes used in the air, this consists of the flight spoilers to raise symmetrically to reduce the speed and increase the rate of descent.The ground spoilers are control surfaces that raise to kill the lift over the wing and to create drag.Flight spoliers and ground spoilers are operated hydraulically via the PCU's and ground spoiler control valves, extending the flight spoilers in the air will extend the flight spoilers varied by the movement of the speed brake lever.Ground spoilers are disabled once in the air due to the ground spoiler shutoff vallve and active when the speed brake is armed and the gears in contact with the runway.In total the boeing (non varient) 737 has 6 spoilers on each wing, and only two of the remaining spoilers are used as ground spoilers and the remaining 4 used in flight".

About drag, I do fly gliders in real world, and we have to use the rudder all the time in turns (especially when we enter or leave a turn) because of adverse yaw, (I think it was).I know that this effects almost all the planes in real world. Is this simulated in the NGX? There is an addon called Glider X for FSX, they have simulated it well.

About drag, I do fly gliders in real world, and we have to use the rudder all the time in turns (especially when we enter or leave a turn) because of adverse yaw, (I think it was).I know that this effects almost all the planes in real world. Is this simulated in the NGX? There is an addon called Glider X for FSX, they have simulated it well.

I believe that the yaw damper on almost all airliners these days co-ordinates turns automatically, even when hand flying.Good point though, is this simulated in the NGX? Don't think I've seen it done on any other addons.

The yaw damper is there to prevent things like dutch roll. The coordinated turn aspect is simply a side-effect as it targets zero slip angle. If you have slip in a turn, the turn is not coordinated.Calling the use of in-flight spoilers "speed brakes" is really a misnomer. They kill some of the lift generated by the wing, increasing angle of attack (and thus drag). In order to maintain altitude (or a vertical rate of descent) the nose must be raised slightly to counter the loss of lift (otherwise the aircraft will either start a descent or descend at a higher rate). It is the fact of raising the nose slightly in response to the increased angle of attack, that results in the illusion of an increase in deceleration rate whilst other flight parameters appear unaffected (this is not true; the pitch attitude is now slightly higher to maintain a desired vertical rate). The spoilers themselves do induce a bit of drag, but it is small compared to the induced drag from the increased angle of attack.The reason the drag reduces at lower altitudes/speeds is because induced drag reduces as a function of lower TAS, thus the drag induced as a result of increased AoA is reduced. Remember that in the speed brake function, the spoilers don't deploy very much at all into the airflow.Compare this to an actual speed brake (think BAe 146, Fokker 70/100 or Buccaneer) that has a very large area exposed to the airflow and increases drag many magnitudes more than any spoiler-based speed brake would. Due to the very large area, they are also very effective at low altitudes/speeds.You can do a test: use the auto-flight to maintain a speed/altitude, and extend the speed brakes. You will see an increase in pitch attitude in response to the loss of lift, and an increase in engine thrust to overcome the increase in drag as a result of increased AoA. The aircraft is again holding speed/altitude, but note the pitch attitude is now a couple of degrees higher in response to countering the increase in AoA.If the aircraft was not using the auto-flight to maintain speed/altitude, the effect of spoiler deployment would result in an increase in vertical descent rate whilst maintaining the same speed.Note also that deployment of the spoilers in flight results in a pitch-up response as the center of pressure is shifted forwards.Best regards,Robin.

The spoilers themselves do induce a bit of drag, but it is small compared to the induced drag from the increased angle of attack.

Yep, Yep, Yep, Yep, and once again.....Yep.

The yaw damper is there to prevent things like dutch roll. The coordinated turn aspect is simply a side-effect as it targets zero slip angle. If you have slip in a turn, the turn is not coordinated.

I know the yaw damper is there to surpress dutch roll - that's its primary purpose. However dutch rolls occur when the aircraft occilates at certain frequencies, which yaw dampers are specifically designed to eliminate. This isn't achieved by simply targeting zero slip, it's more sophisticated than that.Turn co-ordination isn't a by product of having a yaw damper, it's an additional feature added to them.Reading up on this it seems that depending on the aircraft, turn co-ordination is only available in certain phases of flight. Which phases are applicable to the 737 I've not discovered yet.

As some of us know, none of the planes in FS is affected by adverse yaw.By the way; Correction on my last post, the Addon is called Discus Glider X, and that addon plane has adverse yaw. But what I mean is: When you enter a turn, the ailerons will produce drag on the wing that goes up (easily explained) that makes the nose turn the opposit way which you want for a little while (but still turning the right way), untill the ailerons are neutral. Offcourse the Yaw Damper might help as you say, which is kind of an autorudder then, right?Correct me if I'm all wrong, just want to know.

I can name several products that model adverse yaw.Yaw damper works by measuring lateral accelerations. It then puts in a correction. It is independent of roll angle/rate.Best regards,Robin.

Yaw damper works by measuring lateral accelerations.

Since the yaw damper has no influence on lateral control, only directional control, I doubt that's correct.

Since the yaw damper has no influence on lateral control, only directional control, I doubt that's correct.

Let's start from the top........From the nose to the tail is the LONGITUDINAL axis.From wing tip to wing tip is the LATERAL axis.From the bottom of the fuselage to the top is the VERTICAL axis.These are the three basic planes.Rotation about the VERTICAL AXIS, results in LATERAL ACCELERATIONS (90 degrees out of plane).Directional control is only called such to make it easier to grasp the concept. Direction, referring to heading (you put in left rudder, the nose swings left, and the heading changes in response, thus changing the direction you are pointing). It is not, however, the correct technical term.Best regards,Robin.

Ok now you're talking nonsense.

Directional control is only called such to make it easier to grasp the concept. Direction, referring to heading (you put in left rudder, the nose swings left, and the heading changes in response, thus changing the direction you are pointing). It is not, however, the correct technical term.

Directional control/stability is the correct term. I've no idea why you'd think otherwise, or what you'd propose is the correct term. Directional control is provided by the rudder, to which the yaw damper is attached. The yaw damper is there to ensure directional stability and has no effect on lateral stability.

From the nose to the tail is the LONGITUDINAL axis.From wing tip to wing tip is the LATERAL axis.From the bottom of the fuselage to the top is the VERTICAL axis.These are the three basic planes.Rotation about the VERTICAL AXIS, results in LATERAL ACCELERATIONS (90 degrees out of plane).

The longitudinal axis is 90 degrees out of plane as well, so does rotation about the vertical axis produce longitudinal acceleration too? No. In fact no rotation about any axis results in any lateral acceleration. As you correctly identified the lateral axis runs from wingtip to wingtip. Lateral acceleration would therefore require movement in a linear fashion along this axis - something that'll only be caused by turbulence. Buy a book, or simply google this stuff. The info is out there.

I think what he means is that once you start to turn around the vertical axis you could measure a lateral acceleration anywhere on the plane (not on the axis, obviously). If that makes any sense.

Flamin_Squirrel: Let's not split hairs - the yaw damper measures lateral accelerations. If it sensed longitudinal accelerations as you suggest it could, it would also sense the changes in forward speed of the aircraft, as well as gravity as the aircraft pitch changed resulting in spurious inputs in response.With the accelerometers being aligned laterally, they can't sense these forces.May I also suggest that you do not assume what I may or may not know.

The yaw damper is there to ensure directional stability and has no effect on lateral stability.

Correct, from the perspective of the function of the rudder. I am quite clearly talking about how the yaw damper works, and what it is actually sensing - not the same thing, and different terminology applies (as you should know).

As you correctly identified the lateral axis runs from wingtip to wingtip. Lateral acceleration would therefore require movement in a linear fashion along this axis - something that'll only be caused by turbulence.

Incorrect. Any form of motion involving lateral motion (whether it is rotational or not) will result in lateral accelerations. I think you need a Physics 101 class. What will NOT result in lateral accelerations is putting the accelerometers directly over the center of rotation. As you move out from the center of rotation, the greater the rate of acceleration becomes. Ideally, you want the yaw damper in the nose or the tail, as far from the center of rotation as possible, to increase the sensitivity.Best regards,Robin.

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Check this out. http://forum.avsim.net/topic/340367-hi/