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777/767 Aileron Question  
User currently offlineWorldoftui From Sweden, joined Aug 2007, 0 posts, RR: 0
Posted (9 years 10 months 1 week 3 days 14 hours ago) and read 4494 times:

Having flown numerous times on 767/777, a question about the aileron useage.

Having read a previous thread that talked about aileron reversal (sounded kinda scary!), when do the outer ailerons become locked?

Does it happen when the flaps have been retracted? At a certain speed? At a certain height?

Also, I seem to remember something about the 767 inboard ailerons being deployed with the higher flap settings to "reduce the nose-up angle" on landing. Is this correct? Seem to remember them still functionning as they are deflected down, but how would this reduce the AOA?

Mark

10 replies: All unread, jump to last
 
User currently offlineCdfMxTech From United States of America, joined Jul 2000, 1338 posts, RR: 27
Reply 1, posted (9 years 10 months 1 week 3 days 12 hours ago) and read 4419 times:

The Outboard airlerons on both aircraft are locked out as a function of airspeed (Lockout at cruise speeds).

The Inbd (Iand Outbd on the B777) Ailerons droop as a function of flap position. They droop increases as flaps increase. (Don't have specific numbers).

This droop is to assist the TE flaps.


User currently offlineWorldoftui From Sweden, joined Aug 2007, 0 posts, RR: 0
Reply 2, posted (9 years 10 months 1 week 3 days 12 hours ago) and read 4410 times:

This droop is to assist the TE flaps.

Forgive me, but "TE flaps? Trailing Edge?


Mark


User currently offlineDeltaGuy From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 10 months 1 week 3 days 12 hours ago) and read 4409 times:

Bout the only time I ever see them in use is on approach, as you're creeping along at 155-ish knots. In flight, it's all flaperons, and you'll see minor movements from them, resulting in larger roll movements...amazing how effective they are.

As said, they are inhibited by airspeed, I think they become effective around 170? knots...will have to go back and check that.

DeltaGuy


User currently offlineCdfMxTech From United States of America, joined Jul 2000, 1338 posts, RR: 27
Reply 4, posted (9 years 10 months 1 week 3 days 12 hours ago) and read 4407 times:

Yes, Trailing Edge Flaps.

User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 5, posted (9 years 10 months 1 week 3 days 10 hours ago) and read 4375 times:

As said, they are inhibited by airspeed, I think they become effective around 170?

The AMM only says "lockout occurrs at cruise speeds". Probbly somewhat higher than 170kts.



757 Most beautiful airliner in the sky!
User currently offlineCdfMxTech From United States of America, joined Jul 2000, 1338 posts, RR: 27
Reply 6, posted (9 years 10 months 1 week 3 days 7 hours ago) and read 4323 times:

For the B767, the lockout is at around approx 278 kts or Mach .59.

From Maintenance Training Manual
- Outboard Aileron Lockout Schedule


User currently offlineAJ From Australia, joined Nov 1999, 2381 posts, RR: 24
Reply 7, posted (9 years 10 months 1 week 3 days ago) and read 4273 times:

For the 767 the inboard ailerons droop at flap settings of 5 and above. This can be observed on the control position indicator on the status page.

User currently offlineDeltaGuy From , joined Dec 1969, posts, RR:
Reply 8, posted (9 years 10 months 1 week 2 days 23 hours ago) and read 4269 times:

Went back and looked at the 767 pubs...

"The aileron lockout control system permits full travel of the outboard ailerons at low speeds and locks out the outboard ailerons at high speeds. This provides the required roll authority at low airspeeds and prevents over controlling at high airspeeds."

There are six spoiler panels located on the upper wing surface of each wing. Spoilers on opposing wings are symmetrically paired. Spoiler panels are used as speedbrakes to increase drag and reduce lift, both in flight and on the ground. The spoilers also supplement roll control in response to control wheel commands.

I said 170-ish knots because I usually only see them really in use when the aircraft is slowed down, i.e. with flaps out...like Dl757 said, the texts doesnt specify an actual airspeed. When you see them in action, the flaperons/spoilers only have to move a tad bit to get a good roll going.

Hope that helps!

DeltaGuy


User currently offlineWorldoftui From Sweden, joined Aug 2007, 0 posts, RR: 0
Reply 9, posted (9 years 10 months 1 week 2 days 19 hours ago) and read 4234 times:

Thanks everyone for the replies. And all in plain english for a "non-tecchie!"

Cheers  Smile

Mark


User currently offlineOly720man From United Kingdom, joined May 2004, 6604 posts, RR: 11
Reply 10, posted (9 years 10 months 1 week 1 day 15 hours ago) and read 4115 times:

Yes, wings are very flexible. The tip ailerons can generate enough force at high speed so a downwards deflection will bend the wing nose down and the effect of the aileron is cancelled by the twist of the wing or, indeed, reversed.

This is, partially, why the F18, for example, has a large wing twist between root and tip so the tip points downwards. THe angle is reduced in flight simply because the wing lift bends the wing.

Andy



wheat and dairy can screw up your brain
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