Aileron Question

[tim96]

Hi all,

I noticed in real life, that the outboard aileron in parking position of the 747-400 is not droop. The inbord is cleary hanging down. In PSX i mentioned in the EICAS Display that the outboard and inbord ailerons begin to droop after cut off the hydraulic demand pump selectors. Do i something wrong? Or is there something different?
Thank you for answering!

On the 747- 8 the ailerons are both hanging down. I watched it at Frankfurt Airport Someone there told me, that it would be a technical different wing, because the outboard aileron would be a Flaperon???

I am looking forward for your answers.

Best Regards from sunny EDDK

Volker

[Avi]

Nice observation about the outboard ailerons.
I checked photos from my last 2 B744 flights (last year and 3 years ago) and indeed while the inboard ailerons are dropped down, the outboard are not.
If I had these photos when the flight controls were implemented in PSX (this coming week 5 years ago), maybe I would have catch it  .

In PSX the ailerons and elevators start to drop down when there is no hydraulics pressure to support the specific surface (each surface is powered by two hydraulic systems except the outboard elevators which powered by a single system) and they drop relative fast (comparing to the real aircraft) but Hardy made this on purpose.

Cheers,

[John H Watson]

I noticed in real life, that the outboard aileron in parking position of the 747-400 is not droop.

This topic came up during beta testing. I noted the aileron positions of numerous 744 aircraft. There was so much randomness, it was hard to say what they were supposed to do. Hydraulics unpressurised, the wind catches the ailerons and moves them to various positions, even up. The outboards probably have good counterbalancing on them.

The Boeing Maintenance Manual says the outboards may be slightly drooped when pressurised (EDIT) as seen on the synoptic).

(After re-reading the manual: During indicator calibration, the rig pins should be installed and the position transmitter calibrated so that the indication is -0.6 degrees (or units) on the outboards, as seen on the CMC Flight Control Maintenance Page)

[John H Watson]

A picture of some random positions...

http://www.iinet.net.au/~b744er@ozemail.com.au/PSX/StrangeFlightControlConfig.JPG

[tim96]

Thank you very much for answering. I do a little research today and found 2 simular questions on another platform. The answer sounds interesting, but sure i' am not able to proof it, may you guys know more. It has something do do with the balance, what John also has mentioned before.


"On the 747-400, only the outboard aileron and outboard elevator get balanced".

Reference: Boeing Document D634U103, 51-60-01 & 51-60-02"

Here is the link to that conversation: http://www.airliners.net/aviation-forums/tech_ops/read.main/105616/

here another answer:


On the 747 for example:
Balanced: O/B Ailerons, Elevators & Upper rudder (except the 744)
Unbalanced: I/B Ailerons, Elevators & Lower rudder (& Upper 744)

The 744 uses the speed/actuator method so if the lockout actuator fails the affected O/B aileron will remain operational and the conditions of the MEL will have to be followed, which is to limit the speed to 225kts/M0.73."

The Link: http://www.airliners.net/aviation-forums/tech_ops/read.main/148870

What do you think? Could this be the reason for the not drooping outboard ailreon?

[Jeroen Hoppenbrouwers]

Somewhat related, I recently spent a few days on the flight deck of parked 737s. The birds were electrically fully powered but otherwise dead. On the 737, there are cables between the yoke and the elevator (plus hydraulic assist). The column moved fiercely forward and backward at unpredictable moments due to wind, you really need to watch out where you put your knees.


Hoppie

[John H Watson]

"On the 747-400, only the outboard aileron and outboard elevator get balanced".

After further reading (of my technical manuals), I can confirm this. There are six tungsten* counterbalance weights on each outboard aileron.

There was some discussion of aerodynamic fairing effects during PSX testing. I don't know if the outboard aileron droop you are seeing is due to aerodynamics (wind effect) or something else. Not all control surfaces on aircraft assume a fully faired position due aerodynamic effects.

Here's a photo of the flight control display on KLM Air France showing slight droop on the outboards

http://www.airliners.net/photo/Air-France-Cargo/Boeing-747-428F-ER-SCD/0863350/L

*Replaces the depleted uranium balance weights on the original 747s.

[localiser]

On the 737, there are cables between the yoke and the elevator (plus hydraulic assist). The column moved fiercely forward and backward at unpredictable moments due to wind, you really need to watch out where you put your knees.

On windy days in the 737 when you were trying to do something in your seat and the control column kept whacking you in the knees you'd sometimes select an electric hydraulic pump on to pressurise the system and that'd stop it from flailing around in the wind.

[Hardy Heinlin]

So, in PSX, the outboard ailerons and outboard elevators should droop just 3% instead of 80%?

Approximately.

[Britjet]

I think they only droop a fraction, if at all.
Peter

[Hardy Heinlin]

Outboard ailerons no longer droop in PSX 10.0.9-beta12:

http://aerowinx.com/board/index.php?topic=3685.0




(Outboard elevators are not modified because they do droop on the photos.)