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Enroute Airbus A380 wake flips Challenger business jet upside down

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Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#251

Post by dorfsmay »

cyberferret wrote: post #137
dorfsmay wrote: post #128

Earlier quoted context omitted.

The shape of the wing makes a huge difference, so a plate or a piece of wood wouldn't make a good wing, but it is still able to fly. Proof? Inverted flight on low power aircraft and gliders.

And as I have mentioned elsewhere on here - I have flown inverted a few times, and to do so take a tremendous amount of forward pressure on the control stick to even try and attempt to hold altitude while inverted, in order to counteract the wings natural (slight) positive AoA and the tendency for the wing to move towards it upper surface. In fact, most of the aircraft I have flown would not be able to sustain invert…

> The fact that full aerobatic and military jets do, is because they usually don't have that curved 'fish' shape cross section, but are usually symmetrically shaped on the top and bottom of the wing.

Fair enough, it is symmetrical, but still has a lot of shape to it - only time I've been inverted was in a grob 103, and was a passenger for that part of the flight, here's the cross section of it's little sister which is also fully aerobatic:

https://en.wikipedia.org/wiki/File:Grob_G_102_Standard_Astir...

My point in the gp post was that since one can fly inverted, the shape of the wing is not the only fact. I think you and I are saying the same thing.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#252

Post by andruby »

paulajohnson wrote: post #161
andruby wrote: post #118

Earlier quoted context omitted.

Yes. I think that all small aircraft pilots will read/hear about this story. They might even practice the event in simulators. And all of them will avoid passing under a large aircraft at 180 degrees. Source: my father is an airline pilot and they always take the time to learn from severe incidents.

If you are flying in controlled airspace then you fly where ATC tell you, not where you happen to think would be a good idea. If you want to change course for any reason you ask ATC. The only exception would be to avoid an imminent collision.

Good point.

Is there any leeway to adjust your heading slightly and then correct back?

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#253

Post by mirimir »

phumbe wrote: post #7

For anyone interested, there are several great youtube videos[1-4] that show the wakes (the wingtip vortices in particular) created by various aircraft. This incident brings the Reduced Vertical Separation Minima (RVSM)[5] into question. Strategic Lateral Offset Procedure (SLOP)[6] can be used used to avoid such incidents. [1] https://www.youtube.com/watch?v=E1ESmvyAmOs [2] https://www.youtube.com/watch?v=dfY5ZQDzC5s…

From #6:

> In addition to mitigating en route midair collision hazard, SLOP is used to reduce the probability of high-altitude wake turbulence encounters. During periods of low wind velocity aloft, aircraft which are spaced 1000 feet vertically but pass directly overhead in opposite directions can generate wake turbulence which may cause either injury to passengers/crew or undue structural airframe stress. This hazard is an unintended consequence of RVSM vertical spacing reductions which are designed to increase allowable air traffic density. Rates of closure for typical jet aircraft at cruise speed routinely exceed 900 knots.

Seriously, "unintended consequence"? It seems quite obvious in retrospect.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#254

Post by dorfsmay »

votingprawn wrote: post #175
cyberferret wrote: post #137

Earlier quoted context omitted.

And as I have mentioned elsewhere on here - I have flown inverted a few times, and to do so take a tremendous amount of forward pressure on the control stick to even try and attempt to hold altitude while inverted, in order to counteract the wings natural (slight) positive AoA and the tendency for the wing to move towards it upper surface. In fact, most of the aircraft I have flown would not be able to sustain invert…

> I'd be interested to see in this thread, who here has actually studied aeronautical engineering I studied Aerospace Engineering (PhD in Aerodynamics), and I stay out of internet conversations over "how" lift is generated. For me it is one of those topics that is just not worth debating. It seems that people get _really_ attached to their personally preferred theory of lift.

You should write a blog entry on current theory, and post "I'm an expert, here are the current theory(ies), I will not debate about it", or point to a wikipedia page that is accurate in your opinion.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#255

Post by gingerbread-man »

tbabb wrote: post #119
EGreg wrote: post #103

"until the crew was able to recover the aircraft exercising raw muscle force" Any more info on that??

Under normal flight conditions, the aircraft's engine supplies hydraulic power to the flight controls (flaps, ailerons, elevator), like power steering in your car. Very necessary for big/fast aircraft, as the plane is heavy and the force of the air resisting the movement of those control surfaces is very high. If the engines fail, you still need to be able to control the plane, so there is something called a ram air…

Cessna pilot here-- I've never flown an aircraft with hydraulic controls. (Small planes use pushrods or cables to actuate the controls. It's all muscle power for us.)

The physics of flight produce a very useful convenience: the amount of force needed to effect a particular degree of attitude change (e.g. a 10 degree bank) remains the same, regardless of speed. Planes up to the size of small jets (the Cessna Mustang, for instance) use fully manual controls with no power assistance. The Challenger is a bit bigger, but even after the remaining pressure in the hydraulic system completely dissipated, I doubt more than 30lbs of pressure would have been required to actuate the controls. And the rotational inertia of the turbines should have provided at least some assistance on top of that. (I have no idea what would have happened if an airliner lost both engines simultaneously in a stall.)

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#256

Post by xapata »

geezerjay wrote: post #157
xapata wrote: post #75

Earlier quoted context omitted.

Private planes also crash far more often than standard airline flights. Case in point: Chapecoense.

IIRC, the Chapecoense flight was done by a private charter company which provided services to football teams. That was not a private jet incident at all.

charter ~ jet

No?

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#257

Post by subroutine »

eCa wrote: post #153
sgustard wrote: post #136

Earlier quoted context omitted.

Every once in a while I have to re-realize how amazing this phenomenon is. The only thing in nature that flies are birds which weigh a few ounces. Nothing human-scale flies. Cars don't fly. Yet, the flying machines we decide to build weigh a million pounds and fly simply by going fast until the air lifts them up . That is some ludicrous black magic.

Imagine seeing the quetzalcoatlus[1] fly... [1] https://en.wikipedia.org/wiki/Quetzalcoatlus

Possibly James Cameron's inspiration for Toruk Makto

https://www.youtube.com/watch?v=M7NZERuFNEw

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#258

Post by knodi123 »

mirimir wrote: post #253
phumbe wrote: post #7

For anyone interested, there are several great youtube videos[1-4] that show the wakes (the wingtip vortices in particular) created by various aircraft. This incident brings the Reduced Vertical Separation Minima (RVSM)[5] into question. Strategic Lateral Offset Procedure (SLOP)[6] can be used used to avoid such incidents. [1] https://www.youtube.com/watch?v=E1ESmvyAmOs [2] https://www.youtube.com/watch?v=dfY5ZQDzC5s…

From #6: > In addition to mitigating en route midair collision hazard, SLOP is used to reduce the probability of high-altitude wake turbulence encounters. During periods of low wind velocity aloft, aircraft which are spaced 1000 feet vertically but pass directly overhead in opposite directions can generate wake turbulence which may cause either injury to passengers/crew or undue structural airframe stress. This hazar…

unintended? of course! that's not the same as unexpected :-)

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#259

Post by jandrese »

tbabb wrote: post #119
EGreg wrote: post #103

"until the crew was able to recover the aircraft exercising raw muscle force" Any more info on that??

Under normal flight conditions, the aircraft's engine supplies hydraulic power to the flight controls (flaps, ailerons, elevator), like power steering in your car. Very necessary for big/fast aircraft, as the plane is heavy and the force of the air resisting the movement of those control surfaces is very high. If the engines fail, you still need to be able to control the plane, so there is something called a ram air…

It also means they were lucky they weren't flying a fly-by-wire aircraft.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#260

Post by knodi123 »

ryguytilidie wrote: post #215
phumbe wrote: post #7

For anyone interested, there are several great youtube videos[1-4] that show the wakes (the wingtip vortices in particular) created by various aircraft. This incident brings the Reduced Vertical Separation Minima (RVSM)[5] into question. Strategic Lateral Offset Procedure (SLOP)[6] can be used used to avoid such incidents. [1] https://www.youtube.com/watch?v=E1ESmvyAmOs [2] https://www.youtube.com/watch?v=dfY5ZQDzC5s…

Cool example of vortices on an F1 car as well: https://www.youtube.com/watch?v=ZlDnd3B1rhs

That looks like lens flare to my untrained eye. I would never have thought that was smoke in a vortex.
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