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Right Petal during 180 Autorotation


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I had a discussion with someone today regarding the following:

 

(It's an actual question on the commercial exam [FAA-H-8083-21, Chapter 11]) In the ASA Commercial Book (2007), it's # 5714 on page 2-23.

 

Anyway..

 

During a 180 autoration, if full right pedal is applied during the turn, what will happen to the following...

 

1. Rotor RPM

2. Airspeed

3. Sink Rate

4. Aircraft attitude

 

I say.. Rotor RPM will increase, airspeed increase, sink rate increase, and the nose will pitch down and be out of trim.

 

NOTE: In a 269C

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nose will have a pitch up tendency in a 269C due to the horizontal stabilizer positioning (compared to left pedal input that would REALLY cause a nose down situation...ie. nose tuck)

 

I'm out of town right now so I can't give you the direct quote on this condition.. but it's in an owner manual supplement on the 269 series.

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Rotor RPM would DECREASE. In an auto you have almost full right pedal (Zero degrees). If you push it full right, you're actually putting negative pitch in the blades which causes a load, therefore lower RPM.

 

Airspeed would drop because you're out of trim.

 

Decent rate.....it would be in a slip, so I would think it increase. However, if the RRPM is less, so is rate of decent. I'd have to try it to figure it out.

 

I don't know enough about 269s to comment on the attitude.

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Bristol,

 

 

Swami says…….

 

Nose would want to pitch down (tuck), Increase in sink rate, RRPM would decrease (unless aft cyclic was applied), Indicated airspeed would decrease (out of trim)

 

BTW...are we turning left or right? Or does it matter?

 

 

Now, if you are asking what the FAA’s answer would be on the knowledge test, probably something way out there. I’ll have to look it up

 

Fly Safe

Clark B)

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Bristol,

Swami says…….

 

Nose would want to pitch down (tuck), Increase in sink rate, RRPM would decrease (unless aft cyclic was applied), Indicated airspeed would decrease (out of trim)

 

BTW...are we turning left or right? Or does it matter?

Now, if you are asking what the FAA’s answer would be on the knowledge test, probably something way out there. I’ll have to look it up

 

Fly Safe

Clark B)

 

 

Clark,

 

A right turn.

 

I had this discussion with Neal and Brian. The FAA answer in the book says RRPM Increas, pitch down, airspeed increase and sink rate increase. At least that's the answer for the commercial written.

 

Paul

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Clark,

 

A right turn.

 

I had this discussion with Neal and Brian. The FAA answer in the book says RRPM Increas, pitch down, airspeed increase and sink rate increase. At least that's the answer for the commercial written.

 

Paul

 

And for students experiencing it for the first time remember to add, eyes go wide, knuckles turn white, sphincter clenches, and lunch returns to the back of the throat. :P

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Pitch down is an incorrect answer for Hughes/Schweizer 300

 

From the Operators manual Hughes 269 (not the poh)

5-9 effect of improper trim on attitude

B. In Power -Off Flight

 

1. Use of Left Pedal or Insufficient Right pedal in power-off flight will cause an immediate rolling yaw to the left and the nose to pitch down.

 

2. The Use of Excessive Right Pedal in power-off flight will cause the nose to yaw to the right and pitch up slightly.

 

NOTE

 

As LEFT pedal is applied, the yaw turns the rotor disc to the left of the line of flight and projects the tail boom to the right of the line of flight. Impact pressure and positive forces, IN AUTOROTATIVE DESCENT, on the large surface area and high dihedral angle of the horizontal stabilizer increase the rate at which the nose will pitch down and roll to the left.

 

As Excessive RIGHT pedal is applied, even though the yaw turns the rotor disc out of the line of flight, it projects the tail boom to the left and, IN AUTOROTATIVE DESCENT, the pitching down of the nose is STOPPED by negative forces on the horizontal stabilizer causing the nose to pitch up slightly.

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Being out of trim will always result in increased rate of descent, whether it's excessive right or left pedal. Everything being equal, the airspeed should decrease because of the increased drag, but a combination of high descent and perhaps nose down can show an increase in airspeed, although you aren't making more speed across the ground, just toward the ground. Pitch up or down is a function of the model, and there is no one correct answer in all cases.

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