# Centrifugal force and direction

1. Aug 16, 2011

### rajeshmarndi

we wouldn't experience the centrifugal force unless we change direction.

Suppose we are flying an twin engine airplane and one side engine fails, to counteract this the pilot applies opposite rudder and flies straight.

Would we experience the centrifugal force and does the turn indicator ball emerged in a fluid inside an instrument lies still central.

2. Aug 16, 2011

### LostConjugate

Why would you feel a force if your flying straight?

3. Aug 16, 2011

### DaveC426913

LC makes an excellent point.

BTW, what is your question? You sort of started in the middle. Has someone somewhere tried to convince you about when you might experience a centrifugal force?

4. Aug 16, 2011

### rajeshmarndi

sorry i was little wrong on saying the pilot fly straight. Actually the pilot think he is flying straight when he apply opposite rudder only and see the cantered ball at center.

the rudder pressure and the center ball is not enough to provide information correct. The pilot need to bank(upto 5 degree) towards the good engine too to fly straight. So that when the center ball is 1/2-1/3 out of its center position towards the good engine, the airplane is flying straight.

My question why doesn't the ball center, when the airplane is flying straight?

What i know it has to do something with the horizontal component of the lift produced by the good engine and rudder force(yaw).

5. Aug 16, 2011

### DaveC426913

There is not enough information here for me.

What is the ball doing? What exactly is it supposed be measuring, and by what mechanism does it do so?

LC's comment still stands. If the plane is flying in a straight line (even if that straight line is out-of-true from the plane's longitudinal axis via yaw, pitch or roll), then it will not experience any centrifugal force.

6. Aug 16, 2011

### rcgldr

Assume the left engine went out. Then the right engine generates a torque to the left, which needs to be counterd with right rudder. This balances out the torque, but the side force from the rudder causes the plane to skid to the left. The dihedral in the wings will respond with a right bank to a left skid, but it may be too much or not enough. The pilot will have to bank a bit to the right to keep the fuselage in line with the flight path (relative to the air), but this will show up as a right bank on the ball indicator. However if there was a streamer at the front of the canopy (windshield), it would be blown straight up once the flight mode was "coordinated".

7. Aug 16, 2011

### DaveC426913

Yes, what rcgldr said. :tongue:

8. Aug 16, 2011

### rajeshmarndi

the attachment picture describes completely what i'm asking.

its the slip to the dead engine(say left engine) when only rudder pressure is applied and the ball centered(indicating the plane flying straight) but not flying straight.

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9. Aug 16, 2011

### rcgldr

As shown in your diagram, the plane is flying straight, but it's banked to one side, so the occupants feel the lean, but since the path is straight and not circular, there are no centripetal forces or reactions involved.

10. Aug 16, 2011

### rajeshmarndi

i'm concerned with the ball indicator and not the occupant, so when it shows centered why the plane is slipping.

and when the ball is kept 1/2-1/3 of its cage to the good engine, the airplane flight path is in the direction of the nose of the airplane.

11. Aug 16, 2011

### DaveC426913

The ball indicates roll. The plane is rolled 2-3 degrees to starboard and is being maintained that way.

What exactly is the problem?

12. Aug 17, 2011

### rajeshmarndi

I think i'm wrong in my thinking that if the ball is center, the airplane fly straight in the direction of its nose.

then i wander, would the ball center when the airplane is flying on its desired track making cross-wind correction, nose pointing in a different direction then its flight path.

13. Aug 17, 2011

### DaveC426913

The ball is not indicating direction of flight (that would be a yaw indicator); it is indicating roll.

14. Aug 17, 2011

### rcgldr

The ball just indicates if the net force felt is straight down or a bit to the side. If the aircraft is flying straight but with the wings tilted to one side of the other (slip), the ball goes to one side due to the direction of gravity relative to the orienation of the aircraft. If the wings and engine outputs are level, but the rudder is offset causing the aircraft to turn, the ball goes to one side due to centripetal acceleration. There's a seperate attitude indidator that shows pitch and bank (roll) angles, and there may be a computerized additude and heading reference indicator that also includes yaw angle.

15. Aug 17, 2011

### rajeshmarndi

rcgldr: the information was really helpful. Thanks a lot.