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Are you using Developer Mode or made changes in it?
no
Have you disabled/removed all your mods and addons?
yes
Brief description of the issue:
In both official gliders only the very last few cm of yaw string twists (as if the first part was very stiff) while in real live airflow is linear and yaw string very nimble thus the string should be also quite straight (with obvious flutter, but similar all along the string). Please compare with RL video: https://youtu.be/xiGhxIzp5Xw?t=279 - at around 4:47 pilot uses too much right leg thus air attacks glider more from the left side so the yaw string skews wholly (never only the last few cm) to the right side. Yaw string is the most important instrument in glider to perform correct coordinated turns, thus allow pilot to correctly use rudder and correct use of rudder is crucial in preventing stalls. Many instructors are angry because student-pilots after simulators do not have correct leg work because simulators do not signal it good enough (lack of noticable enough adverse yaw at least in simulated DG-1001 will be similar culprit). Current strange curved bending behaviour also prevents from understanding what it really signals at given time.
Also during towing by plane yaw string should be way more chaotic due to prop wash (which also should affect the glider with turbulence) - see https://youtu.be/xiGhxIzp5Xw?t=429 for yaw string behaviour reference
Provide Screenshot(s)/video(s) of the issue encountered:
(my green line shows expected skew, red line mark section that unnaturally keeps mostly unaffected by airflow)
Real life reference (from video above) when yaw string signals an uncoordinated turn - notice it is straight
Detailed steps to reproduce the issue encountered:
In SU11 fly any official glider straight, observe how only end of the yaw string bends, while it should skew starting at the attachement point, do an uncoordinated turn - that is with only ailerons, without using rudder - see how yaw string curves even more instead of bending straight
PC specs and/or peripheral set up if relevant:
Build Version # when you first started experiencing this issue:
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Do you have the same issue if you follow the OPâs steps to reproduce it?
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Do you have the same issue if you follow the OPâs steps to reproduce it?
Yes
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This issue is also very noticeable in the Glider Training > Basic Handling tutorial.
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1 Like
Do you have the same issue if you follow the OPâs steps to reproduce it?
yes
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Do you have the same issue if you follow the OPâs steps to reproduce it?
Yes
This is a simple & common (for yawstrings) modelling error given the good objective to have the yawstring curve as it follows the curved canopy.
The detail that is missed is the yawstring PIVOTS at itâs root, i.e. the full yawstring angle should be applied to an animation connecting the base of the yawstring to the piece taped to the canopy. Then a flex/bone (i.e. curve) animation can be applied to the length of the yawstring given whatever direction it is now pointing, this is purely to wrap it round the canopy. Most modellers first attempt does have the entire movement of the yawstring as a single bone animation which typically that leads to the mistake seen.
Elite-mode yawstring, as implemented on all the freeware gliders:
Have three animations:
(1) The pivot at the base, which sets the macro direction of the whole string i.e. itâs animated with the âyawstring angleâ simvar and pivots directly to that angle, with no bending involved (itâs a piece of wool with negligible stiffness)
(2) Use a bone animation to curve the length of the string so it follows the curve of the canopy. This can also be controlled by the âyawstring angleâ simvar but the curve simply to fit the canopy is modest and shouldnât be confused with the big angle pointing the yawstring in the correct direction in the first place.
(3) Have an independent âtipâ animation (i.e. a left-right jiggle) which can be moved randomly with both the frequency and amplitude of the jiggle controlled by AIRSPEED. This can be surprisingly realistic for such a simple additional feature, but itâs worth having because the yawstring is stuck right in front of the face of the pilot so itâs pretty important.
If you want to see a GOAT yawstring, look at the freeware K7 which moves in all three directions (try a tail slideâŠ). FWIW that yawstring doesnât use a bone animation at all which gives a clue that bones are awesome but not actually the most important detail.
B21
6 Likes
Can confirm. Yaw string modeling is incorrect. For one the bending plus the reaction to rudder input - correct is: rudder hard right the yaw string blows to the very right equivalent from the noseâs deviation to the flight direction.
1 Like
I noticed this and it is really important: the yawstring is a vital instrument for coordinated flight, whose backup, a Turn and Slip indicator, isnât in the instrument panel. I endorse this bug report!
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Do you have the same issue if you follow the OPâs steps to reproduce it?
Yes
Provide extra information to complete the original description of the issue:
If relevant, provide additional screenshots/video:
Do you have the same issue if you follow the OPâs steps to reproduce it?
Yes
Provide extra information to complete the original description of the issue:
If relevant, provide additional screenshots/video:
Do you have the same issue if you follow the OPâs steps to reproduce it?
YES
Provide extra information to complete the original description of the issue:
If relevant, provide additional screenshots/video:
Do you have the same issue if you follow the OPâs steps to reproduce it?
Yes
Provide extra information to complete the original description of the issue:
Yaw string is simply an indicator of airflow over that part of the aircraft and should move as a single line to indicate which way the air is flowing over the string, pivoting or bending only from the point of attachment. Hence when an aircraft is âyawingâ or âskiddingâ in a turn the airflow is no longer directly aligned to the aircraft centreline.
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Do you have the same issue if you follow the OPâs steps to reproduce it?
YES
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The yaw string animation is quite ridiculous as it stands.
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Do you have the same issue if you follow the OPâs steps to reproduce it?
yes
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Effect is disturbing in training
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I deleted my post because the string is actually not broken, I was mislead by this post mentioning it but the Problem is something else.
As you can see in this picture the air stream is coming from the left of the planes nose.
I put myself in a left turn and straightened all rudders.
THIS IS WRONG!
The correct way it should fly is like this.
The only thing I changed is some rudder input to the left into the turn.
In conclusion:
The Adverse Yaw effect is only happening when additional drag is created through ailerons movement (turning into a turn) and after you straighten out it should not be active anymore and the plane should follow into the air stream.
1 Like
Yes, itâs a huge bug, for me. I fly in real life and, as mentioned above, this string is critical to have a good symmetrical flight.
Itâs important it gets fixed asap so we can fly with them in the same way we fly in real life. I also noticed that the global inertia of this yawn string is too big. It should be more reactive.
3 Likes
Do you have the same issue if you follow the OPâs steps to reproduce it?
Yes
Provide extra information to complete the original description of the issue:
A real wool yaw doesnât have any rigidity. It shouldnât blend this way, even if itâs on a curve glass. We doesnât know at wich point the flight is assymetric.
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I will add a little more to your explanation. Of course, in practice/reality a glider will need correction in a constant turn using rudder and aileron, sometimes the controls can be crossed at moments during certain conditions in a turn, (especially when the thermal lift is very strong and there is a lot of churning turbulent air and rapidly ascending and descending air which effects the air speed of the glider). It can get complicated!
Charles. (40 years of gliding experience!)
1 Like
