Yaw indicator vs front feather

[Martillo1]

I have observed that in medium/high speed conditions the yaw indicator does not coincide with the front feather, I mean that if I trim the helo using the bank and the yaw indicators, the feather indicates a sideslip to the left. If I trim using the feather an the bank indicator, the yaw indicator shows the ball to the right.

 

Default weather conditions so no wind.

 

The sempiternal question: bug or feature?

[Frederf]

I've had a similar issue. Try testing with the HDG hold function off, perhaps by using the Flight Director or even turning off the channel altogether. I've heard that the AP HDG hold function can cause trimming the ball center to be frustrating.

 

Also there's a visual parallax issue that makes the ball look off center when it is centered. It's worse on the SADI than the primary ADI.

 

I'm beginning to think that proper ball-center flight actually involves some bank to fly straight.

 

Also I'm amazed the manual actually calls the instrument a "yaw indicator" >.< "If there is no yaw in the flight path" how can there be yaw in a path? Is the path yawing? Normal Western aviation folks call it a slip indicator.

[Martillo1]

For the sake of aerodynamics, I trust the feather.

[26-J39]

Just a guess here but i would think that at high speeds the vertical feather my be affected by the rotor tilt due to the variation in lift from advancing and retreating blades.

[Griffin]

Also, this should be taken into account:

 

"Yaw indicator. Indicating the yaw of the aircraft, this indicator displays a ball in a liquid filled tube. If there is no yaw in the flight path, the ball will be centered. If there is yaw, the ball will be displayed in the opposite direction of yaw. The sideslip indication ball moves by local acceleration so it will not always display the actual sideslip. This depends much on the type of maneuver you are flying."

[Frederf]

I guess that makes sense. If you're flying directly sideways and you're not accelerating in any direction the ball should be at the bottom of the glass. One would clearly be in an extreme situation of "not going where you're pointing" where the ball shows centered.

 

However the converse, you're flying perfectly, should have the ball centered too and not off to the side. Can can we fly perfectly coordinated and the ball is to the side?

[Martillo1]

The question arose in my mind when I centered the ball while flying around 180-200 km/h and my eyes told me the that I was not flying straight, but sideslipping to the left, something corroborated by the feather. However, the ball was centered. Centering the feather put the ball to the right in a noticeable manner, but visually I flew straight.

[Frederf]

That statement is meant to portray the idea that "local acceleration puts the ball in the center" can be accomplished not only in perfectly coordinated straight and level flight but also weird compensations of other accelerations.

 

However the converse should not be true, if you are flying straight and level unaccelerated, then the ball should be in the center.

[Martillo1]

However the converse should not be true, if you are flying straight and level unaccelerated, then the ball should be in the center.

 

Hence my question. My empirical knowledge shows that it is not true in my case.

[JACN]

I like this question had been asked because I have exactly the same experience as Martillo1. I don´t have too much experience in the Shark but after the first few minutes flying her I noticed an incredible high sideslip!. Even keeping trimmed the helo, above 180 kias "the ball" -in my case- goes half to full right....of course feet on ground and wings level condition. I´ve tried both Flight Director ON/OFF with the same bad result.

 

Don´t know if this is the realistic behavior for this aircraft but I find it as an extremely annoying (and dangerous) way of flying :(

[GGTharos]

Most helicopters suffer from some form of inherent sideslip, which means that in the cruise they can either be flown in balance (ball centered) or wings level, but not both at the same time. This sideslip is a result of a number of factors including tail rotor position, main rotor rotation, center of gravity position.

[Frederf]

Most helicopters suffer from some form of inherent sideslip, which means that in the cruise they can either be flown in balance (ball centered) or wings level, but not both at the same time. This sideslip is a result of a number of factors including tail rotor position, main rotor rotation, center of gravity position.

 

And the answer comes down from the golden goose! I had my suspicions but had no clue for sure.

[EinsteinEP]

Actually, the answer comes from http://www.griffin-helicopters.co.uk/lessons/effectsofcontrols.htm.

[Martillo1]

So it seems it is a feature :D:joystick::D

 

So, what is best, ball centered or feather centered?

[sinelnic]

So, what is best, ball centered or feather centered?

 

Let's say that when ED finally models the virtual spine of the virtual pilot, you will be able to make loads of money by selling the virtual chiropractic add-on for the people that fly with the ball off-center...

[Frederf]

Uncoordinated flight is uncomfortable for the pilot? The only way I could think of is having to twist your head/body to look where you're going if it's significantly different from where the seat is facing.

 

I think the best way is to fly with the ball centered and whatever bank is necessary to fly where you're pointed (no slip).

[Martillo1]

Let's say that when ED finally models the virtual spine of the virtual pilot, you will be able to make loads of money by selling the virtual chiropractic add-on for the people that fly with the ball off-center...

 

Hey, then the damage model is not complete, it lacks pilot's :D

[EtherealN]

virtual chiropractic add-on

 

Pfff, ED wouldn't want to simulate magic. :P