Yawing Motions

[Lep 0]

Have been flying my newly bought Discus and have great fun.

But I observed that it tends to yaw around quite easily, even in gentle turns. The yawing is especially obvious with deployed spoilers when coming in for landing. Is it supposed to be like that?

Thanks.

Lep

[J.Schweigler 203]

If all realism sliders are maxed out, everything you feel is intended ;-)

But please explain, more specified, what you mean, then I can explain, what it is, and what you feel. Maybe adverse yaw moment?

[Lep 0]

If all realism sliders are maxed out, everything you feel is intended ;-)

But please explain, more specified, what you mean, then I can explain, what it is, and what you feel. Maybe adverse yaw moment?

I mean, when approaching for landing, I would deploy the spoiler, and do minor left and right rolls to align with runway centreline while descending, that I noticed the yawing motion of the glider. Full realism setting.

[J.Schweigler 203]

I think, what you mean is the adverse yaw moment. You should feel/see it in the air also.

If you deploy ailerons, the wing with the down going aileron produces more and that with the upgoing one less drag. The produces a yaw moment.

For exaple left aileron = left aileron up (less drag) right one down (more drag) = yaw right.

You must control this with rudder. Also on flight. Make sure the yawstring is centered to get the best performance.

During landing do not hold the string centered but the plane well allignet to the runway. (You don't need performance there)

Bests Joachim

[Lep 0]

I think, what you mean is the adverse yaw moment. You should feel/see it in the air also.

If you deploy ailerons, the wing with the down going aileron produces more and that with the upgoing one less drag. The produces a yaw moment.

For exaple left aileron = left aileron up (less drag) right one down (more drag) = yaw right.

You must control this with rudder. Also on flight. Make sure the yawstring is centered to get the best performance.

During landing do not hold the string centered but the plane well allignet to the runway. (You don't need performance there)

Bests Joachim

Thanks, Joachim for your advice.

I'm well aware of adverse yaw. Just that the Discus seems to display a rather high sensitivity to this, even with just a little aileron input. I've never flown a glider before, thus my seeking clarification here.

Anyway, overall I feel the Discus here is a great product. My only issue is in finding good thermals, preferrably without having to turn on the in-game thermal visualization cues. Do you know of any good online reference / guide that I may turn to in understanding this topic? In Fair Weather as well as when set to a wind of about 16-17 knots setting, I usually run out of altitude before I could find another thermal, even when I try flying towards and over ridges. This spoil the experience somewhat to an otherwise nice product.

Lep

[J.Schweigler 203]

In a glider adverse yaw is always far more present than in other planes, because it has long effective wings with ailerons far outside. It also depends on airfoil and aoa.

Regarding thermals:

Load down the latest version of cumulusX! and completely deactivate FSX standard thermals. They're crap.

Then set fair weather and no wind for the first flight. You should be able to find thermals now below the cumulusx! clouds.

Another option for a first nice run is to use ridge lift, wich is easier to use. Put yourself on a flield in the alps and set about 16 kts wind towards a mountain. The air has no other chance than rising at the ridge and you can use this. Just make sure that you're high enough (mountains before the ridge you intend to use produce wind shadows, wich disturb the lift)

Have luck and fun. Joachim

[Lep 0]

In a glider adverse yaw is always far more present than in other planes, because it has long effective wings with ailerons far outside. It also depends on airfoil and aoa.

Regarding thermals:

Load down the latest version of cumulusX! and completely deactivate FSX standard thermals. They're crap.

Then set fair weather and no wind for the first flight. You should be able to find thermals now below the cumulusx! clouds.

Another option for a first nice run is to use ridge lift, wich is easier to use. Put yourself on a flield in the alps and set about 16 kts wind towards a mountain. The air has no other chance than rising at the ridge and you can use this. Just make sure that you're high enough (mountains before the ridge you intend to use produce wind shadows, wich disturb the lift)

Have luck and fun. Joachim

Thanks, Joachim. Yes I've the latest CumulusX and had also deactivated FSX thermals. But the frame-rate took a hit, so I changed to 2-D simplified clouds and everything is ok.

Just did a flight around Salzburg (Austria Pro X). It was great, especially with a 16 knots winds towards mountains. But I noticed the the winds can really suddenly change direction causing very swift and unpredictable change in heading. Wonder if this is a bug with FSX.

Lep

[J.Schweigler 203]

yes it is, the best would be to set only one wind layer

[Lep 0]

On this subject of adverse yawing again, I have done quite several hours of flight in the Discus and am liking it a lot, but the yawing sensitivity can get bothersome, especially on short final, the nose seems to keep oscillating about the yaw axis left and right, left and right, in response to even very small aileron input. When in flight, during turning, this yaw oscillation is also quite noticeable. I've watched several real world glider videos on Youtube and both turnings and landings/approaches in all kinds of gliders seem to show up very little (if any) adverse yawing action.

Does the real Discus also produces very noticeable yawing and oscillating back and forth about the yaw axis? Or am I missing something? Is there any way to tone down this adverse yawing effect?

Thanks.

Lep

[J.Schweigler 203]

Every glider behaves this way, if you don't control it with the rudder. Every small movement of the ailerons has to be controlled with rudder also, to fly coordinated (hold the yawstring centred). What you see in the videos are all gliderpilots that are used to it.

You must simply learn it. You'll get the best experience with rudder pedals. A twist grip is also ok, but mor difficult to handle. Pedals are better.

I suggest to do some roll practise. Fly towards a specific point on the horizon. Now roll the plane right and left and so on while holding the string centered and the heading towards this point. Do this with full and half aileron deflection at different speeds to get used to it.

Cheers Joachim

[Lep 0]

Every glider behaves this way, if you don't control it with the rudder. Every small movement of the ailerons has to be controlled with rudder also, to fly coordinated (hold the yawstring centred). What you see in the videos are all gliderpilots that are used to it.

You must simply learn it. You'll get the best experience with rudder pedals. A twist grip is also ok, but mor difficult to handle. Pedals are better.

I suggest to do some roll practise. Fly towards a specific point on the horizon. Now roll the plane right and left and so on while holding the string centered and the heading towards this point. Do this with full and half aileron deflection at different speeds to get used to it.

Cheers Joachim

Thanks for quick reply.

I currently use the Thrustmaster T16000M joystick, and I have the aileron / elevator / rudder (pedal) joystick sensitivity set to maximum, while all null zone set to zero. Is this advisable? When in short final landing approach lining up with centreline using minor aileron adjustment, do I also have to use rudder to compensate for yaw action?

Lep

[J.Schweigler 203]

do I also have to use rudder to compensate for yaw action?

Of course. Every single movement with both controls. However the faster you get the lower the adverse yaw due to a lower aoa.