'Centering the Ball in forward flight.'

[Fish]

Hi all,

Ive spent a fair few hours in the ka pit now. but still have difficulty centering te ball in normal forward flight. I generally fly with only pitch and roll ap on. I use the slingle trim button, and dont generally trim rudder.

 

I understand thats it not a very efficient way to fly if the slip indicator is not centered. Generally it finds its way to the right, indicating sideslip to starboad, which may have something to do with the rotation direction. of the rotors.

 

Any comments would be great, or reference to other thread/s

[WynnTTr]

I bet it's your rudder. Press Rctrl-enter to turn on a nice little tool that show you exact positions of rudder/cyclic. Trim is hard to recreate here without force feedback gear.

[Skypat]

Hi all,

Ive spent a fair few hours in the ka pit now. but still have difficulty centering te ball in normal forward flight. I generally fly with only pitch and roll ap on. I use the slingle trim button, and dont generally trim rudder.

 

I understand thats it not a very efficient way to fly if the slip indicator is not centered. Generally it finds its way to the right, indicating sideslip to starboad, which may have something to do with the rotation direction. of the rotors.

 

Any comments would be great, or reference to other thread/s

 

hello,

 

just for your information about the real thing ;)

 

disabling one of these AP (heading, pitch, roll) is not allowed at all in the real life.

you should use FD button instead or you should trim each time your flight attitude change

 

best regards

Slypat

[EvilBivol-1]

Post #8, 12, 17, 20, 21:

http://forums.eagle.ru/showthread.php?p=591793#post591793

Edited April 20, 2009 by EvilBivol-1

[Corvus]

I bet it's your rudder. Press Rctrl-enter to turn on a nice little tool that show you exact positions of rudder/cyclic. Trim is hard to recreate here without force feedback gear.

 

I don't think it's his rudder. At speed above 150 or so Ka-50 has a tendency to roll to the right (bigger force of upper rotor?), to counter it you need to add some left cyclic. After doing that you'll notice that the ball is off center to the right. So to flight straight you need to both apply left cyclic and right rudder.

 

PS: Hello everyone:) Been lurking around those forums since lock on FC:O

PS II: Sorry for my english

 

Best regards

Corvus

 

...Too slow!

[EtherealN]

which may have something to do with the rotation direction. of the rotors.

 

The rotors are counter-rotating. The "sum" of their rotation speed is zero, as is the torque unless you have rudder input since the latter increases the angle of attack on one blade disc while the other disc is lowered in alpha, causing differential torques from the discs and then you get rotation.

 

It is also entirely possible to have one rudder input serve to give you good clean flight in one direction but be totally off after another turn, depending on wind direction etcetera.

 

And yeah, don't fly without the yaw channel. That's a court-martial offense IRL. :P

[muamshai]

I usually use route mode to keep my chopper in the desired direction. Say, changed the heading to 170 deg, applied route (no waypoints), disabled route.

[WynnTTr]

I don't think it's his rudder. At speed above 150 or so Ka-50 has a tendency to roll to the right (bigger force of upper rotor?), to counter it you need to add some left cyclic. After doing that you'll notice that the ball is off center to the right. So to flight straight you need to both apply left cyclic and right rudder.

 

PS: Hello everyone:) Been lurking around those forums since lock on FC:O

PS II: Sorry for my english

 

Best regards

Corvus

 

...Too slow!

I'm not sure about this. I centre rudder, put the ball in the middle and literally can take my hands off the cyclic. Doesn't roll to the right at all, flies straight.

[Corvus]

I'm not sure about this. I centre rudder, put the ball in the middle and literally can take my hands off the cyclic. Doesn't roll to the right at all, flies straight.

 

Strange. At what speed? Look at controls indication in AirTito's post here http://forums.eagle.ru/showpost.php?p=592330&postcount=12 Rudder to the right, cyclic to the left.

...On second thought, maybe AP is keeping you straight? Do you have DH switch on?

 

Best regards

Corvus

Edited April 20, 2009 by Corvus

[EtherealN]

Corvus, if you need rudder right and cyclic left to fly straight and level, just trim after achieving that and you are able to release it. All you need to have on for that is the three standard AP damping channels of yaw, pitch and bank.

[Copperhead]

Just reset the trimmer whenever you have difficulty trying to re-center the ball.

 

If you continue to correct the side slip with rudder movements and trim repeatedly to overwrite the previous settings, the error will gradually accumulate and make things worse.

 

:joystick:

[Corvus]

Corvus, if you need rudder right and cyclic left to fly straight and level, just trim after achieving that and you are able to release it. All you need to have on for that is the three standard AP damping channels of yaw, pitch and bank.

 

I know i have to trim to get hands off flight, and i do fly with three AP channels on. I'm writing about situation when you're gaining speed, and are trying to get the ball centered.

[EtherealN]

Well, when you are accelerating you are continually changing the forces imparted onto the aircraft by the airflow, so a really really small rudder input that kept you balanced at 90km/h will impart a stronger force when you reach, say, 180km/h, and this will cause you to have to continually change the inputs as your flight parameters change.

 

The picture of AirTito's only tells you the air and ground speeds on the time of snapping the picture, I don't see direct indication that he is still accelerating.

 

Another point though is that if you have any wind, you should not expect to fly straight relative to the ground just because you have the ball centered. If the volume of air is moving you will fly diagonally compared to the ground. (This is the difference between True Heading and True Track - at least I think that was the english terms for it.)

 

But well, don't expect your aircraft to be entirely permissive of hands off flight while you are accelerating. I'd be surprised if that was possible unless the acceleration is very very slow and thereby allowing you to just make minor trim corrections a little now and then.

[Yskonyn]

Centering the ball is only an aerodynamic indicator. Like Ethereal says it is no indication of wether you're flying straight over the ground.

If you have the ball centered it means that the aircraft is properly trimmed for most aerodynamic efficient (for the lack of a better term) flight.

 

What many people have difficulty with understanding is that in flight any aircraft is dependent on the wind.

Picture a column of air moving over land by the wind. The aircraft will move along with this column of air. By means of control input and propulsion the aircraft is able to travel in a specific direction, but still the wind has impact on its movement.

 

Say you want to travel to Magnetic North without wind. You fly a heading North and the aircraft will fly there. The nose is pointed to the same direction as the direction of the track you fly over the ground.

Now we have a stiff wind from the east, trying to push the aircraft westward. We still want to fly to the north, but if we just fly heading north, the wind will push us westward causing us to fly a sort of spiral or arc over the ground if we keep pointing our nose to the north, much like the flow of water in your fountain in the bathroom.

Eventhough we do not fly a straight line it is very much possible to have the ball centered because the aircraft is flying aerodynamically correct.

 

If, however, we want to fly in a straight line over the ground to the north with a stiff wind from the east we need to correct for the wind and point our nose a bit into the wind, so a bit more to east.

The effect of the wind on our track is called drift and the correction on heading we make to adjust for the wind is called wind correction agle - WCA. The correct heading to fly is heading +/- WCA to get the required track over the ground from A to B.

Here we also have the ball centered in flight.

 

Centering the ball is not related to navigation directly, but more an indicator of the way the aircraft is being flown.

 

The statement True vs Magnetic Heading / Track is related to the reference of which North we use.

The true north of the earth (northpole) is not in the same location as the magnetic north our compass points to. The magnetic north also moves slightly over time to make matters worse (that's why we have variation changes).

[sobek]

When the ball is centered, it simply means that the sideways forces on the ball (and thus, the pilot) are balanced, meaning that the force vector on the pilot points straight down through the seat (in relation to the airframe, not the earth). This is achievable in almost any flight regime (flying straight or in a turn).

[Fish]

I bet it's your rudder.....

 

Na, dont think so. I use the 'AXIS' indicator all the time. Rudder centers perfectly at rest. Constantly trim in forward flight to get correct forward speed/direction, altitude. Dont use the FD mode, im talking about free flight. I can switch to AP anytime when flying to a WP. That does not help me understand the flight dynamics.

 

Don't have rudder trim mapped to my stick. Maybe i should.

[Fish]

hello,

 

just for your information about the real thing ;)

 

disabling one of these AP (heading, pitch, roll) is not allowed at all in the real life.

you should use FD button instead or you should trim each time your flight attitude change

 

Slypat

 

Thanks for reply.

 

I'm not sure what u mean by 'allowed', or by who. I'd be very surprised if RL pilots are not thought how to fly with all combination's of AP on and off, and i can imagine many situations particularly in combat, where they would need the discretion to decide how best use the tools at their disposal.

 

I dont use the FD, just the Abris, and HSI, and i do trim frequently during flight. I am keen to understand the flight dynamics/envelope of the Ka with/withoug all the combination of AP, and flying aids

[EtherealN]

Rudder trims along with everything else, unless you've done something weird.

 

And rudder being centered does not mean you will fly straight. Depending on winds and a whole other bunch of stuff it may well be a slight trim for left or right rudder that you need.

[Fish]

I don't think it's his rudder.................. So to flight straight you need to both apply left cyclic and right rudder.

 

Sounds like a plan. Will need to map my rudder trim. :thumbup:

[EtherealN]

Thanks for reply.

 

I'm not sure what u mean by 'allowed', or by who. I'd be very surprised if RL pilots are not thought how to fly with all combination's of AP on and off, and i can imagine many situations particularly in combat, where they would need the discretion to decide how best use the tools at their disposal.

 

Prepare to be surprised.

 

Flying without AP channels for yaw, bank and pitch is a serious offense for real Ka-50 pilots. They may be taught how to do it, but it is an emergency procedure only - so that they can get home even if they have the AP electronics destroyed by battle damage.

Edited April 20, 2009 by EtherealN
bit of cleanup

[Fish]

The rotors are counter-rotating. The "sum" of their rotation speed is zero, as is the torque unless you have rudder input since the latter increases the angle of attack on one blade disc while the other disc is lowered in alpha, causing differential torques from the discs and then you get rotation.

 

It is also entirely possible to have one rudder input serve to give you good clean flight in one direction but be totally off after another turn, depending on wind direction etcetera.

 

And yeah, don't fly without the yaw channel. That's a court-martial offense IRL. :P

 

Makes perfect sense :thumbup:. And No i dont fly without yaw channel, (except when under extreme flight envelope conditions, it fails to remain active,) as the undampened motion tends to make me queasy.!

[Fish]

.......centre rudder, put the ball in the middle and literally............... .

 

Thats exactly my question. How do u 'put the ball in the middle!

[159th_Viper]

Thats exactly my question. How do u 'put the ball in the middle!

 

Rudder Input and Trim.

[EtherealN]

If the ball is right of centre, give right rudder. If it stays right of centre, give more right rudder.

 

And vice versa.

 

Oh, and when it is in the centre and stationary, trim to maintain that.

[GGTharos]

Thanks for reply.

 

I'm not sure what u mean by 'allowed', or by who. I'd be very surprised if RL pilots are not thought how to fly with all combination's of AP on and off, and i can imagine many situations particularly in combat, where they would need the discretion to decide how best use the tools at their disposal.

 

 

As mentioned before, there is exactly one situation where they'd need to decide to turn off the AP/Stabilization channels: When they are damaged.

It is prohibited to take off without functioning AP channels, and it it prohibited to deliberately turn them off unless they are damaged. At least, in reality it might cost you your career if not your life - the Ka-50 is reasonably stable, but turning those off increases your workload during combat which equates to 'doing it wrong'.

 

 

I dont use the FD, just the Abris, and HSI, and i do trim frequently during flight. I am keen to understand the flight dynamics/envelope of the Ka with/withoug all the combination of AP, and flying aids

 

That's fine for understanding the flight envelope - I mean, we don't have a little training chopper in the sim just for such a purpose, but insofar as the Ka-50 goes, flying it 'without aids' = you're doing it wrong ... at least, you're doing it wrong if you are looking to simulate how the real pilots have to fly.