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Flight (2012 film) - Can airliners fly inverted?

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Old 07-17-2013, 08:13 PM
  #26
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Default RE: Flight (2012 film) - Can airliners fly inverted?


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ORIGINAL: hugger-4641

Exactly right EddieC. I don't remember the flight number, but there was an Airbus a few years ago, I believe a 380, with a composite tail that came off the plane because the pilot was above ''manuevering'' speed and cycled the rudder back and forth in an attempt to get rid of vortex turbulence. I don't think the elevator surface was composite, but the rudder was. If the elevator surface is composite, I highly doubt it would withstand inverted flight. I'm sure someone will correct me if I'm mistaken.
Just to clarify, it was American flight 587, an Airbus 300-600, on Nov 12, 2001. AA587 crashed shortly after takeoff, about 3 miles from JFK. It is likely he didn't even have his flap and slats retracted, therefore would not have been anywhere close to maneuvering speed. The FAA amended this definition in 2010 as a result (SUMMARY: The Federal Aviation Administration amends the airworthiness standards applicable to transport category airplanes to clarify that flying at or below the design maneuvering speed does not allow a pilot to make multiple large control inputs in one airplane axis or single full control inputs in more than one airplane axis at a time without endangering the airplane's structure. The FAA is issuing this final rule to prevent pilots from misunderstanding the meaning of an airplane's maneuvering speed, which could cause or contribute to a future accident)

references: Wikipedia - American airlines flight 587; Maneuvering Airspeed

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Old 07-17-2013, 08:23 PM
  #27
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Default RE: Flight (2012 film) - Can airliners fly inverted?


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ORIGINAL: RV7guy

I have a Van's RV7. It is aerobatic and rated at +6 -3. I have a G meter in the EFIS. I have logged +4 G's in turbulence. I would think that airliners would be rated for greater than +2 G's.

Darwin N. Barrie
Chandler, AZ
Team Futaba
Turbulence will affect lightly wing loaded aircraft to a greater degree than heavier aircraft. that's why heavier model airplanes fly better in high winds than lighter models. I flew f-16 and f-111s - on low level flights the f-16s ride was stiff, like a corvette; the f-111 rode like Cadillac.
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Old 07-17-2013, 08:53 PM
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Default RE: Flight (2012 film) - Can airliners fly inverted?


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ORIGINAL: eddieC

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Most airliners and cargo aircraft can take the G's if lightly loaded as the stress limits are for aircraft at or near gross load.
Uh,... sorry, no. Load limits apply to fixed items of the aircraft, not just the wings and such. By 'taking the G's', do you mean a bit higher G to reach the load limit at gross? If so, then no.
Most airliners are stressed for +2.0, -0.0 G. The fixed items, like engines, batteries, etc., still feel their normal weight, so 2G is 2G. The airspeed may vary based on weight for certain maneuvers. Review maneuvering speed and limit load factors. Q: In turbulence, can you go faster, or slower, if the airplane is lightly loaded ?
Can you post proof on the C130 aerobatics?
Design load limits apply to the aircraft at maximum takeoff weight otherwise you would have separate load limits for empty and full of fuel, people, cargo, etc. Even at 2Gs, the add'l stress of 40,000lbs of payload/fuel could be catastrophic. And the designers always have about a 100% safety factor built in, so if the placarded load limit is 2gs, then it can safely handle the jolts from turbulence.

Every flight manual I have ever studied has always said to slow down in turbulence to the slowest practical airspeed. Although you can go faster in a lightly loaded plane, believe me, the jolts are going to feel worse. For the 737 and Md-83, turbulence penetration airspeed was about 280kias. Heavier aircraft (b-767,777, A-340,380) may require higher airspeeds.

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