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Jeff_B

Angle Of Attack Round Dial

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Hi all, just curious as to why the needle on the round dial/AOA is at an angle sloping down when at 0.0 eg. when it is parked on the ground.I have the manuals and have read and understand the scale/markers etc. Why wouldnt it be displayed as level/horizontal to indicate 'current' angle which is straight?I hope this makes sense, and someone can give me the reason if there is one. Obviously Boeing have designed it this way for a reason. Thanks in advance, and look forward to an answer or explanation,Cheers

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Not aimed at you Jeff, just a general note:You guys should maybe stop trying to find problems or "bugs" from the demonstration videos. The video was made, like Robert already pointed out, with an early version of the NGX. I feel like a broken record, because no matter how many times this line is written or said, there are always people who are on the lookout for "obvious missed things".There is a beta team (a wide one :)) at work, along with the technical team of course, who are working on the plane all the time. There is no sense in trying to find problems in these demos. We are doing that on your behalf, and trust me... the beta team members are more than capable of doing that job.Instead: you should take note of the countless of things that are demonstrated in the videos already available via PMDG themselves and via AoA. Just a note: from the videos you will just get a small glimpse of what the real sim environment actually feels like. When you are at the controls and everything around you just is there. And not just the visuals... everything. It's an entirely different story from even the highest quality of videos you can watch.You all will enjoy the released NGX immensely.Tero

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I am gonna make a wild guess at it and say that a plane will never really have a negative angle of attack. Even in level flight you have a postive angle of attack.

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Hi all, just curious as to why the needle on the round dial/AOA is at an angle sloping down when at 0.0 eg. when it is parked on the ground.I have the manuals and have read and understand the scale/markers etc. Why wouldnt it be displayed as level/horizontal to indicate 'current' angle which is straight?
First of all, it's fixed at 0.0 when on the ground and speed below 80 knots. Then your assuming current AOA was level is a little hard to confirm, as when parked there is not exactly an AOA since there is no airflow (assuming no wind). That's why the probe itself usually hangs down (at its "min AOA" stop) and simply isn't straight (but IIRC not all α vane models exhibit this behavior). Then if you assumed the horizontal scale marker was 0.0, it's not. The one at around 4-5 o'clock is 0, the next one (the horizontal one) is 5.
I am gonna make a wild guess at it and say that a plane will never really have a negative angle of attack. Even in level flight you have a postive angle of attack.
Not sure if that ever occurs during normal flight without any weird gusts, but the scale range starts at well below zero (at -6 to be precise) so there's gotta be a reason for it. Once you have the bird in your hands try to push the yoke violently, maybe you can force a negative AOA somehow that way (I doubt it). :(sig.gif

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First of all, it's fixed at 0.0 when on the ground and speed below 80 knots. Then your assuming current AOA was level is a little hard to confirm, as when parked there is not exactly an AOA since there is no airflow (assuming no wind). That's why the probe itself usually hangs down (at its "min AOA" stop) and simply isn't straight (but IIRC not all α vane models exhibit this behavior). Then if you assumed the horizontal scale marker was 0.0, it's not. The one at around 4-5 o'clock is 0, the next one (the horizontal one) is 5.Not sure if that ever occurs during normal flight without any weird gusts, but the scale range starts at well below zero (at -6 to be precise) so there's gotta be a reason for it. Once you have the bird in your hands try to push the yoke violently, maybe you can force a negative AOA somehow that way (I doubt it). :(
In a steep dive you have a negative AOA Although generally you have a positive AOA which is why the needle is more down instead of being in the middle.

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which is why the needle is more down instead of being in the middle.
No it isn't. Read above. "In the middle" is 5 degs AOA.sig.gif

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In a steep dive you have a negative AOA Although generally you have a positive AOA which is why the needle is more down instead of being in the middle.
If you're inverted, maybe. But not too steep.

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inverted and going the wrong way, meaning aft side pointing to the velocity vector. That would give you negative AoA.

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inverted and going the wrong way, meaning aft side pointing to the velocity vector. That would give you negative AoA.
And the urge to don a parachute. It'll give you that too.

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Hi all, just curious as to why the needle on the round dial/AOA is at an angle sloping down when at 0.0 eg. when it is parked on the ground.
Maybe it is for the same reason why PDF shows altitude -6, flight director shows negative pitch - this may be part of specially selected ground-initialization. If aircraft is not moving it is impossible to even say what its AOA is so this may very well be an initial 'condition'.

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And the urge to don a parachute. It'll give you that too.
Hah yes. Will certainly need a parachute. That sort of manuver may be easy for the Shuttle in LEO, but it is strongly suggested to avoid such a thing in the atmosphere if landing the aircraft and walking away from it is part of the objective.

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The logic behind it is because on a scale from -6 to ~20, 0 falls much closer to -6. They are trying to keep the same scale, as well as make the change noticeable. If the change was 1:1, you would barely notice it so they have to exaggerate the AOA meter. The exaggerated change means that if 0 degrees were level, 20 would have to read around 80 on the dial, completely unrealistic. So what they did was rotate the dial a little so the AOAs that you would be looking at the meter for appear more realistic.

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Not aimed at you Jeff, just a general note:You guys should maybe stop trying to find problems or "bugs" from the demonstration videos. The video was made, like Robert already pointed out, with an early version of the NGX. I feel like a broken record, because no matter how many times this line is written or said, there are always people who are on the lookout for "obvious missed things".There is a beta team (a wide one :)) at work, along with the technical team of course, who are working on the plane all the time. There is no sense in trying to find problems in these demos. We are doing that on your behalf, and trust me... the beta team members are more than capable of doing that job.Instead: you should take note of the countless of things that are demonstrated in the videos already available via PMDG themselves and via AoA. Just a note: from the videos you will just get a small glimpse of what the real sim environment actually feels like. When you are at the controls and everything around you just is there. And not just the visuals... everything. It's an entirely different story from even the highest quality of videos you can watch.You all will enjoy the released NGX immensely.Tero
Wasnt trying to find problems nor report a "bug" just asking a simple question on the the display of the dial.We are all going to enjoy it thats a given. Shes the real deal.

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