flyer101flyer
30th Oct 2020, 15:06
I know that the gimbal axis of the "turn coordinator" is tilted while the gimbal axis on a "turn rate indicator" is purely longitudinal-- that's not the question here-- here's the question--
Several posts on PPruNe have suggested that the gyro wheel on a "turn coordinator" spins counterclockwise as viewed from the right, so that the top of the gyro wheel is spinning toward the pilot. This would be opposite to the direction of spin of the gyro wheel on a "turn rate indicator". It would be require that the gyro cage be connected to the symbolic airplane on the face of the instrument by direct gearing, so that the symbolic airplane tilts to the left when the gyro assembly tilts to the left. Also this arrangement would tend to make the instrument under-indicate the turn rate when the G-loading is unusually high. Also this arrangement would seem to present some calibration difficulties, because in a normal steady turn the gyro assembly would tilt in the direction that tips the gyro spin axis away from parallel to the earth, rather than in the direction that tends to keep the gyro spin axis roughly parallel to the earth.
Here are some such posts:
https://www.pprune.org/tech-log/82721-turn-gyro-axis.html#post791017 (#13)
https://www.pprune.org/tech-log/528255-turn-rate-indicator-turn-coordinator-looping-error.html#post8164645 (#2)
Those are both from the same guy, but I know I've seen it from others too, can't find the posts right now. See for example this post on a different aviation forum--
https://aviation.stackexchange.com/questions/56125/during-partial-panel-flying-in-what-ways-is-a-turn-rate-indicator-more-useful/56126#56126
Yet all the diagrams and videos that I've been able find clearly show the gyro wheel on the "turn coordinator" spinning clockwise as viewed from the right, so that the top of the gyro is spinning away from the pilot. This is the same arrangement that is used on the "turn rate indicator". Also the reverse gearing that makes the symbolic airplane tilt opposite to the direction that the gyro assembly is tipping, is clearly visible.
Here are some such links:
https://en.wikipedia.org/wiki/Turn_and_slip_indicator#/media/File:Turn_indicators.png
https://www.aopa.org/news-and-media/all-news/2019/january/flight-training-magazine/how-it-works-turn-coordinator
https://www.youtube.com/watch?v=a4iLtZPp_-8
https://www.youtube.com/watch?v=WbaRm12nRL4&feature=youtu.be&t=107
https://www.youtube.com/watch?v=hVsx4XWafXg&feature=youtu.be&t=431
What gives? Was the opposite direction of spin used on the gyro wheels of some "turn coordinators"? Can anyone definitively confirm this? What makes, what era, or in what aircraft? And why?
Thanks.
Several posts on PPruNe have suggested that the gyro wheel on a "turn coordinator" spins counterclockwise as viewed from the right, so that the top of the gyro wheel is spinning toward the pilot. This would be opposite to the direction of spin of the gyro wheel on a "turn rate indicator". It would be require that the gyro cage be connected to the symbolic airplane on the face of the instrument by direct gearing, so that the symbolic airplane tilts to the left when the gyro assembly tilts to the left. Also this arrangement would tend to make the instrument under-indicate the turn rate when the G-loading is unusually high. Also this arrangement would seem to present some calibration difficulties, because in a normal steady turn the gyro assembly would tilt in the direction that tips the gyro spin axis away from parallel to the earth, rather than in the direction that tends to keep the gyro spin axis roughly parallel to the earth.
Here are some such posts:
https://www.pprune.org/tech-log/82721-turn-gyro-axis.html#post791017 (#13)
https://www.pprune.org/tech-log/528255-turn-rate-indicator-turn-coordinator-looping-error.html#post8164645 (#2)
Those are both from the same guy, but I know I've seen it from others too, can't find the posts right now. See for example this post on a different aviation forum--
https://aviation.stackexchange.com/questions/56125/during-partial-panel-flying-in-what-ways-is-a-turn-rate-indicator-more-useful/56126#56126
Yet all the diagrams and videos that I've been able find clearly show the gyro wheel on the "turn coordinator" spinning clockwise as viewed from the right, so that the top of the gyro is spinning away from the pilot. This is the same arrangement that is used on the "turn rate indicator". Also the reverse gearing that makes the symbolic airplane tilt opposite to the direction that the gyro assembly is tipping, is clearly visible.
Here are some such links:
https://en.wikipedia.org/wiki/Turn_and_slip_indicator#/media/File:Turn_indicators.png
https://www.aopa.org/news-and-media/all-news/2019/january/flight-training-magazine/how-it-works-turn-coordinator
https://www.youtube.com/watch?v=a4iLtZPp_-8
https://www.youtube.com/watch?v=WbaRm12nRL4&feature=youtu.be&t=107
https://www.youtube.com/watch?v=hVsx4XWafXg&feature=youtu.be&t=431
What gives? Was the opposite direction of spin used on the gyro wheels of some "turn coordinators"? Can anyone definitively confirm this? What makes, what era, or in what aircraft? And why?
Thanks.