Flaperon Vs. Alieron

[tsa737 6]

Hi, Just a quick question, what is the difference between a flaperon and an alieron?

 

Thank you

[downscc 1,327]

The news has been showing a wing diagram with the flaperon highlighted with a big red arrow. They're right for a change.

 

It is a control surface about midway along the wing trailing edge length. Swept wing aircraft have used these for decades for a combination of roll control and flap surface. They're pretty big on the B777!

 

Wikipedia has a little pic but AVSIM is being a putz about letting me post a link to it here. Sorry.

[Avantime 81]

IIRC the inboard ailerons on the 777 'droops' down when flaps are selected, making them part of the flap. But they still move around when roll is commanded and that's why they're called flaperons. Airbus aircraft have uninterrupted full-length flaps and rely on the outboard ailerons and spoilers for roll control.

[kevinh 409]

IIRC the inboard ailerons on the 777 'droops' down when flaps are selected, making them part of the flap. But they still move around when roll is commanded and that's why they're called flaperons. Airbus aircraft have uninterrupted full-length flaps and rely on the outboard ailerons and spoilers for roll control.

Airbus ailerons droop with the flaps too. They just don't call them flaperons.

[pschlute 37]

I love the name "flaperon".  Concorde had trailing edge control devices on it's delta wing which controled bank just like an aileron, and pitch just like an elevator. They were called "elevons"

[Avantime 81]

Airbus ailerons droop with the flaps too. They just don't call them flaperons.

 

Correct. For Airbuses it's called "Aileron Droop Function".

[downscc 1,327]

I might have my histories mixed up, but I think Boeing adopted the flaperon for the B-52 and B-707 due to the bad experience they had with the B-47.  The B-47 was a testbed of sorts, many lessons learned that made the descendent airplanes so popular (B-52 still flying).  One big lesson was jet tuck and how to avoid that... only one B-47 survived jet tuck and hundreds were lost due to it.  The flaperon was created to avoid roll reversal, which is when an aileron deflection warps the wing and the effect is the opposite of desired... a left roll input results in a right roll. Much more survivable than jet tuck but still not appreciated by flight crews.  The control surface could have started out as just an inboard aileron then it didn't take long to add the flap feature.  The B-777 flaperon also has a task of making poor piloting techniques on final work out better for the pilot by automatically unloading the flap feature if speed is too high.

[petedob 3]

So what's the difference a flaperon and an aerilon?

[kevinh 409]

 

 

I might have my histories mixed up, but I think Boeing adopted the flaperon for the B-52 and B-707 due to the bad experience they had with the B-47. The B-47 was a testbed of sorts, many lessons learned that made the descendent airplanes so popular (B-52 still flying). One big lesson was jet tuck and how to avoid that... only one B-47 survived jet tuck and hundreds were lost due to it. The flaperon was created to avoid roll reversal, which is when an aileron deflection warps the wing and the effect is the opposite of desired... a left roll input results in a right roll. Much more survivable than jet tuck but still not appreciated by flight crews. The control surface could have started out as just an inboard aileron then it didn't take long to add the flap feature.

Yes, but those inboard ailerons on the B-47 and subsequent Boeings had no flap droop so they weren't flaperons. As you say introduced to prevent wing twist causing roll reversal, just like the use of differential spoilers. IIRC Boeing didn't call this control surface a flaperon until the 777.