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Topic: Flight Balance With One Wing Lost.
Posted 2012-10-25 11:57:38 and read 5459 times.

Hi guys and gals,

I watching NGC's Air Crash Investigation about Chalk's Ocean Airways Flight 101, and yeah, I know, you need both wings to fly (except the Israeli F-15 in '94?). But what happens when a wing breaks off? Does the wing, that is still attached, flip upward due to the increased lift on the side with the wing or down due to the increase weight?

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 13:18:25 and read 5418 times.

If a wing seperates, the remaining wing will have no opposing moment on the opposite side of the airplane, so it will roll up and over the top...

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 13:40:55 and read 5400 times.

 Quoting Poadrim (Thread starter): But what happens when a wing breaks off? Does the wing, that is still attached, flip upward due to the increased lift on the side with the wing or down due to the increase weight?

If you'd like to see a visual of this happening, take a look at the crash videos of the FedEx MD-11 in NRT or the United DC-10 in Sioux City. In both crashes, the landing gear failed, which caused the spar to break. This separated one wing from the airplane, which caused the rest of the airplane to roll over until the other wing contacted the ground and was upside down.

In this video you can clearly see what happens when the left main landing gear fails and the wing spar breaks. The other wing which is still achieving lifts causes the airplane to roll until it is upside down.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 13:55:34 and read 5390 times.

Aight, thank you. But some how it's seams more logic that the weight of the remaining wing vs. the life momentum should in best case stay level(I know it don't, but still)

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 14:47:42 and read 5347 times.

 Quoting Poadrim (Reply 3):But some how it's seams more logic that the weight of the remaining wing vs. the life momentum should in best case stay level(I know it don't, but still)

At the moment immediately prior to your wing separation, each wing is lifting its own weight, plus half the weight of the rest of the airplane (opposite wing excluded). When the wing separates, the opposite wing is now lifting its own weight, plus trying to lift the full weight of the rest of the airplane (minus the separated wing). Since the lift is horribly off center, the plane flips over.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 14:54:47 and read 5337 times.

 Quoting Poadrim (Reply 3):Aight, thank you. But some how it's seams more logic that the weight of the remaining wing vs. the life momentum should in best case stay level(I know it don't, but still)

If you remember free body diagrams from physics class, the wing is creating a net force up, while the fuselage is a net force down. So while the airplane as a whole would fall out of the sky and go down, relative to the fuselage, the intact wing is going to go up and roll the airplane over.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 15:42:21 and read 5307 times.

Well then, thank you guys! Much appreciated help

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 16:02:26 and read 5287 times.

No problem. Just think of the wing as a helium balloon.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 18:08:07 and read 5223 times.

 Quoting Roseflyer (Reply 7):Just think of the wing as a helium balloon.

On a conveyor belt...

[Edited 2012-10-25 18:08:35]

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 20:30:47 and read 5157 times.

 Quoting Poadrim (Reply 3):Aight, thank you. But some how it's seams more logic that the weight of the remaining wing vs. the life momentum should in best case stay level(I know it don't, but still)

If the weight of the wing would outweigh the lift, then there is really no point in having a wing?

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-25 23:22:52 and read 5108 times.

 Quoting moose135 (Reply 8):Quoting Roseflyer (Reply 7):Just think of the wing as a helium balloon. On a conveyor belt... [Edited 2012-10-25 18:08:35]
 Quoting saafnav (Reply 9):If the weight of the wing would outweigh the lift, then there is really no point in having a wing?

How fast would a helium balloon without wings have to move on a conveyor in order to takeoff

And what if it has one wing on the RH side

/Lars

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-26 05:07:08 and read 5010 times.

 Quoting saafnav (Reply 9):If the weight of the wing would outweigh the lift, then there is really no point in having a wing?

Point taken, I should have known that.

 Quoting Roseflyer (Reply 7): No problem. Just think of the wing as a helium balloon.
 Quoting moose135 (Reply 8):On a conveyor belt... Big grin
 Quoting Larshjort (Reply 10):How fast would a helium balloon without wings have to move on a conveyor in order to takeoff And what if it has one wing on the RH side /Lars

I LOL'd, really. Thanks!

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-27 00:10:26 and read 4689 times.

 Quoting Poadrim (Thread starter):Does the wing, that is still attached, flip upward due to the increased lift on the side with the wing or down due to the increase weight?

Evidently, it will flip up and then rapidly assume a negative AOA and then stall.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-27 03:15:26 and read 4644 times.

Flip up and over before gravity takes over.

On the IAF F15 story.....was the loss of wing imbalance countered by the skill of the pilot using thrust as a compensation....amazing feat.....

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-27 09:06:56 and read 4591 times.

 Quoting HAWK21M (Reply 13):On the IAF F15 story.....was the loss of wing imbalance countered by the skill of the pilot using thrust as a compensation....amazing feat.....

That and the fact that most of the aircraft was actually part of the lifting surface.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-27 10:35:10 and read 4570 times.

 Quoting HAWK21M (Reply 13):On the IAF F15 story.....was the loss of wing imbalance countered by the skill of the pilot using thrust as a compensation....amazing feat.....

In addition to what DocLightning said (the aircraft was nowhere close to losing 50% of its lifting surfaces), the F-15 also has augmented stability in the flight controls. This helps to reject even very large disturbances, like significant asymmetric lift. At least annecdotally, the pilot in that case had no idea that the damage was as bad as it was until after he landed.

Tom.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-27 12:20:29 and read 4538 times.

 Quoting tdscanuck (Reply 15):In addition to what DocLightning said (the aircraft was nowhere close to losing 50% of its lifting surfaces), the F-15 also has augmented stability in the flight controls. This helps to reject even very large disturbances, like significant asymmetric lift. At least annecdotally, the pilot in that case had no idea that the damage was as bad as it was until after he landed.

That's what I heard. It wasn't until he got out of the cockpit that he saw what had happened.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-28 02:41:44 and read 4393 times.

 Quoting tdscanuck (Reply 15):At least annecdotally, the pilot in that case had no idea that the damage was as bad as it was until after he landed.

Usully the case.....reminds me of a B732 lading back after a hydraulic failure only to realise on ground that the caue was a loss of a MW along with the brake, broken at the axle

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-28 03:48:02 and read 4372 times.

 Quoting HAWK21M (Reply 13):On the IAF F15 story.....was the loss of wing imbalance countered by the skill of the pilot using thrust as a compensation....amazing feat.....

And he wasn't able to counter the loss of a wing until he used afterburner.. an option no airliner (anymore) has. So it was partly the fact that the F-15's flat underbelly contributes a good amount of lift, partly that he used afterburner to power thru it, and partly that he wasn't aware the wing was gone. He has said that had he knew the extent of the damage, he would've bailed.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-29 00:54:20 and read 4218 times.

 Quoting HaveBlue (Reply 18):he wasn't aware the wing was gone. He has said that had he knew the extent of the damage, he would've bailed.

I'm sure such a situation would never have been simulated before too on the type ever.....

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-29 17:14:38 and read 4064 times.

 Quoting HaveBlue (Reply 18):He has said that had he knew the extent of the damage, he would've bailed.

Also an option that no airliner has...

 Quoting HAWK21M (Reply 19):I'm sure such a situation would never have been simulated before too on the type ever.....

I'm wondering how one would go about rendering such a simulation accurately.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-30 02:58:04 and read 3997 times.

Wind tunnel?

Perhaps it could work with a really slow aircraft (a glider?) and a ludicrous amount of sideslip...

Never mind maneuverability.

David

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-30 07:37:00 and read 3942 times.

 Quoting flyingturtle (Reply 21):Perhaps it could work with a really slow aircraft (a glider?) and a ludicrous amount of sideslip...

I would not think so. You still have all weight on one side and all lift on the other. Sideslip wont help you with that.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-30 11:02:35 and read 3907 times.

Hm, and how about using full *upward* flaps deflection on the first few feet of the wing (measured from the glider's body), and normal downward deflection of the flaps on the rest of the wing? Though, you need to shift the pivot point into the wing, away from the fuselage...

...well, there has already been the Blohm & Voss 141...

David

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-30 15:43:38 and read 3829 times.

 Quoting DocLightning (Reply 14):That and the fact that most of the aircraft was actually part of the lifting surface.

That and the fact that the missing wing exposed the ungodly huge elevator behind it to free airflow. Those things respond differentially to roll command (which would be at or near the stop...) - I'm sure he was getting a good bit of lift out of the elevator on the wingless side.

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-10-30 15:59:32 and read 3876 times.

 Quoting flyingturtle (Reply 23): Hm, and how about using full *upward* flaps deflection on the first few feet of the wing (measured from the glider's body), and normal downward deflection of the flaps on the rest of the wing? Though, you need to shift the pivot point into the wing, away from the fuselage... ...well, there has already been the Blohm & Voss 141...

If your ailerons were big enough it could probably work. But they would need to be big. The outboard wing would have to creat the same negative lift as the fuselage provides with the inboard wing section having to create twice the amount of lift normally produced by two whole wings.

And the Bv 141 still had a wing on each side of the fuselages.

/Lars

Topic: RE: Flight Balance With One Wing Lost.
Posted 2012-11-03 23:43:31 and read 3476 times.

 Quoting DocLightning (Reply 20):Also an option that no airliner has...

Well there were a few SSTs back in the day...

Topic: RE: Flight Balance With One Wing Lost.