What happened to Air France Flight 447
Discussion
c7xlg said:
yep... that is the video. I was after the one of a B707 being rolled as I thought that had a glass of water in at at well but found this one instead, which includes filling the glass up from a jug!
I don't know about the b-52... at a guess the exaggerated wing droop when fully loaded and static results in some twisting of the wing and hence changing AoA as airspeed increases and the wing lifts up during the (jato assisted) take off roll...
F-8 Crusader has/had interesting AoA properties when flying slowly to.....
The reason I said the B-52 is that when it takes off/lands, the nose is lower than the tail and is the most bizarre thing to witness. If you saw a still photo, you would swear it was going to impact the ground.I don't know about the b-52... at a guess the exaggerated wing droop when fully loaded and static results in some twisting of the wing and hence changing AoA as airspeed increases and the wing lifts up during the (jato assisted) take off roll...
F-8 Crusader has/had interesting AoA properties when flying slowly to.....
The F-8 moved the front of the entire wing assembly up as a I recall in order that the relative position of the aircraft to the flight deck could remain level due to the short main gear lenght/long fuselage overhang towards the rear and so could take off and land without dragging the back of the aircraft along the ground
XB70 said:
True, but if at a constant speed on the motorway the water would be level and veering left or right, the cup of water would indidicate a directional change.
I did it a few flights ago when we were cruising along and the plane was nose high (could be felt by walking and also putting a pen on the table and seeing where it went) and the info screen was showing a constant altitude.
However, a better result was obtained when I poured the water into an empty salad tray thing that was rectangular in shape and orientated it longways on the axis of travel - the 'pitch (?)' of the aircraft was much more apparent then.
I'll shut up now and go back to my seat in economy, put on a movie and console myself that we would impact so quickly I would not even have time to process what had happened.
Funny thing is that on the last trip to Oz earlier this year, the HK-SYD legs were on an A330 and I remember thinking about AF447 and wondering what happened.
How do you know that the water wasn't tipping back due to the aircraft accelerating into a headwind?I did it a few flights ago when we were cruising along and the plane was nose high (could be felt by walking and also putting a pen on the table and seeing where it went) and the info screen was showing a constant altitude.
However, a better result was obtained when I poured the water into an empty salad tray thing that was rectangular in shape and orientated it longways on the axis of travel - the 'pitch (?)' of the aircraft was much more apparent then.
I'll shut up now and go back to my seat in economy, put on a movie and console myself that we would impact so quickly I would not even have time to process what had happened.
Funny thing is that on the last trip to Oz earlier this year, the HK-SYD legs were on an A330 and I remember thinking about AF447 and wondering what happened.
It's all sooo confusing
AndyACB said:
How do you know that the water wasn't tipping back due to the aircraft accelerating into a headwind?
The pilot would know that though.Anyone knows that you can barrel roll and keep constant +G straight 'down'; but the AF Airbus was not doing aerobatics. Well hopefully not; with no references you can think you're flying straight and level and still fly straight into the ground - witness the airliner that had a sticking gyro. Rolled over, down, and in.
Simpo Two said:
The pilot would know that though.
Anyone knows that you can barrel roll and keep constant +G straight 'down'; but the AF Airbus was not doing aerobatics. Well hopefully not; with no references you can think you're flying straight and level and still fly straight into the ground - witness the airliner that had a sticking gyro. Rolled over, down, and in.
What pilot Anyone knows that you can barrel roll and keep constant +G straight 'down'; but the AF Airbus was not doing aerobatics. Well hopefully not; with no references you can think you're flying straight and level and still fly straight into the ground - witness the airliner that had a sticking gyro. Rolled over, down, and in.
AndyACB said:
What pilot
The suggestion was that the glass of water was in the cockpit so the pilot could refer to it if he found the instruments 'a bit difficult'. You seperated this by inferring that the glass of water was in the cabin and being viewed by a passenger - who would not know any other control inputs.That said, AF477 might have flown better without pilots.
XB70 said:
Without looking, is that the video of the fellow pouring juice in into a glass while in a roll? Some sort of high winged twin engined plane?
Anyways, riddle me this:
B-52 on take off or landing - what is the pitch/AoA information on that?
Following taken from the "horses mouth"Anyways, riddle me this:
B-52 on take off or landing - what is the pitch/AoA information on that?
- I have chosen a B-52 for a good reason!*
Best Answer - Chosen by Asker
Hello James -
When I was in the Air Force, I flew B52H models. There are a couple of things going on here that are not easy to see from a casual observer's standpoint:
1. The B52 has large flaps that tend to increase the lift a lot at lower angles of attack. This is good for approach, because the aircraft is designed for no-flap operation at high speed / high altitude, so you need the flaps to get a good look at the runway on final (ADDED: in other words, the flaps help you to fly at lower approach / takeoff speeds with the nose down a bit - lower angle of attack - so that you can see the runway on final and not just clouds).
2. The later model B52s (I think the Hs are the only ones still flying) were overpowered for takeoff. The turbofans that are installed on the H model have a lot more thrust than the aircraft was originally designed for. In fact, there is a "thrust gate" on the throttle quadrant that prevents the pilot from pushing the throttles too far forward during takeoff (this can be overpowered with muscle if necessary during an emergency). The net effect of this extra thrust is to provide a twisting moment on the wings that, especially on the outer wing regions, tends to twist them up and increase the angle of attack further. As a result, the wings are flying at a higher net angle of attack than the fuselage. One thing you will notice is that the tip gear at the end of the wings are in contact with the ground, but tend to lift off as the aircraft proceeds down the runway on takeoff leg. The wingtips start to fly before the rest of the aircraft does.
I don't think it takes off quite nose down, but it does look that way. It's a bit of a weird aircraft.
ADDED: You will notice that, as the flaps are raised and the speed increases, it flies more like a normal aircraft.
Simpo Two said:
The suggestion was that the glass of water was in the cockpit so the pilot could refer to it if he found the instruments 'a bit difficult'. You seperated this by inferring that the glass of water was in the cabin and being viewed by a passenger - who would not know any other control inputs.
That said, AF477 might have flown better without pilots.
I didn't separate it, matey above said he'd carried out the experiment on his tray table with a glass and a serving tray. I just said that he couldn't tell if the water was moving due to acceleration or pitch.That said, AF477 might have flown better without pilots.
It was an idea he thought might work in the flight deck, it won't.
Have a look at Aeroflot 593 accident report and it becomes clear just how difficult it is to separate the different forces without looking at the instruments. A glass of water in that case wouldn't have saved them either.
The facts remain, there was no fault with their engines, airframe or attitude indicators. They had plenty of warnings and working instruments to recover from temporarily frozen pitot probes but still they didn't. How Air France have managed to keep flying with reputation fairly intact is beyond me.
AndyACB said:
The facts remain, there was no fault with their engines, airframe or attitude indicators. They had plenty of warnings and working instruments to recover from temporarily frozen pitot probes but still they didn't.
Agree entirely. It seems that once the autopilot tripped out they had no idea what to do.Simpo Two said:
AndyACB said:
The facts remain, there was no fault with their engines, airframe or attitude indicators. They had plenty of warnings and working instruments to recover from temporarily frozen pitot probes but still they didn't.
Agree entirely. It seems that once the autopilot tripped out they had no idea what to do.
So as I understand it the autopilot trips out on a dark stormy night because of the poorly engineered pitot tube (now replaced fleet-wide) and the two blokes on the flight deck, unsure of speed and attitude, just keep pulling the nose up, thinking that the A330s electronic trickery will prevent them from stalling. It doesn't because with unreliable airspeed it downgrades to direct law. By the time Captain gets into the flight deck he sees what's wrong but it's too late - at 10,000fpm you're going down and pushing forward isn't an option.
From airbusdriver.net:
If Multiple Failures of Redundant Systems occur, the flight controls revert to Alternate Law.
The ECAM displays the message: ALTN LAW: PROT LOST
All protections except for load factor maneuvering protection are lost.
The load factor limitation is similar to to that under Normal Law.
Amber XX's replace the green = attitude limits on the PFD.
A low speed stability function replaces the normal angle-of-attack protection
System introduces a progressive nose down command which attempts to prevent the speed from decaying further.
This command CAN be overridden by sidestick input.
The airplane CAN be stalled in Alternate Law.
An audio stall warning consisting of "crickets" and a "STALL" aural message is activated.
The Alpha Floor function is inoperative.
Ouch. Let's hope lessons are learnt.
From airbusdriver.net:
If Multiple Failures of Redundant Systems occur, the flight controls revert to Alternate Law.
The ECAM displays the message: ALTN LAW: PROT LOST
All protections except for load factor maneuvering protection are lost.
The load factor limitation is similar to to that under Normal Law.
Amber XX's replace the green = attitude limits on the PFD.
A low speed stability function replaces the normal angle-of-attack protection
System introduces a progressive nose down command which attempts to prevent the speed from decaying further.
This command CAN be overridden by sidestick input.
The airplane CAN be stalled in Alternate Law.
An audio stall warning consisting of "crickets" and a "STALL" aural message is activated.
The Alpha Floor function is inoperative.
Ouch. Let's hope lessons are learnt.
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