# AF447: In Flight Breakup?

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#### edhackett

GPS can only report ground speed. Ed

#### sprintman

just in. Terrorist links to two passengers. Stay tuned.

#### outrun

Originally Posted By: edhackett
GPS can only report ground speed. Ed
Thanks for the clarification, based on this capability could not air speed be *accurately* derived by calculating the the time/distance intervals between GPS supplied position fixes? Or are you saying airspeed is a whole different animal than groundspeed? Thanks, I am not an engineer if my questions come off as stupid initially.

#### tom slick

Airspeed is what matters most for operating the aircraft and is relative to headwinds and tailwinds. simplified example: 500 ground speed with a 100 headwind = 600 airspeed, 500 ground speed with 100 tailwind = 400 airspeed.

#### edhackett

Your questions aren't stupid at all. Tom's explanation is pretty good. Air speed is the aircraft's actual speed through the air mass. Groundspeed is the motion of the aircraft relative to the ground within the air mass, and varies with speed and direction of the air mass. It's possible to have a ground speed of 0 or even a negative(backward) airspeed. There is no practical way of calculating airspeed from groundspeed. You would need to know the exact speed and direction of the wind where you are at any given instant. In addition, you also need to know the barometric pressure and temperature of the air to calculate the true airspeed. Temperature, pressure, and the indicated speed though the air have to me measured in real time by the aircraft. I hope that is not clear as mud. Ed

#### kirknbr

Indicated airspeed is the speed of air at the pitot tube. You also can have parts of the airplane "going faster then other parts. Air can be moving faster over different surfaces. This is we are able to get wings to provide lift. The air is going faster over the top of the wing then it is under the wing. Groundspeed will always be the same. Another example is the tips on props. The tips can actually break the speed of sound???(Not a good thing but can happen if not designed correctly) sounds crazy till you think about it a bit. Have you ever seen those free fall sky jump simulators? A large “fan” generates enough wind speed (air speed) to hold the person in the air. The air going over and around him is like he is falling from the sky but he is not falling from the sky. Instead of him rushing thru the air the air is rushing around him. This is really simple if I explained it correctly. You can play word games with people with this and it is fun for a while. The wings are going faster the air plane. Huh? Ground speed is the speed of the ground relative to the plane. Indicated airspeed is the speed of the air relative to the pitot tube (airspeed sensor). True airspeed is the vector difference of the velocity vectors of the aircraft and the air mass, both with reference to the earth's surface. When determining the true airspeed of an aircraft under zero wind conditions and in horizontal flight, the true airspeed of the aircraft is equal to the speed of the aircraft relative to the earth's surface. When determining the true airspeed of an aircraft under non-zero wind conditions an estimation of the windspeed vector is used. (From Wikipedia) http://en.wikipedia.org/wiki/True_airspeed

#### ViragoBry

Saw on the news this morning where they're hauling large parts of the plane out of the ocean. It's a horrible sight. Cant' wait to hear whether or not they find traces or signs of explosives on the parts. As for the black boxes, they're surely at the bottom of the ocean aren't they? Anyone think they go as far as using submersibles to retrieve them?

#### Kestas

Staff member
I got some inside info from people at Boeing, who themselves have connections with people who dismantle airplanes and reverse-engineer competitor aircraft. I got a lot of detail - too much for me to type in a post - but it seems that the airplane simply broke up from the turbulence. The rear fuselage of the Airbus 300 broke off from the airplane, accounting for the 30-mile difference between the two debris fields. To just touch on some of the issues, the load-bearing components of the rear fuselage are made with brittle composite materials, unlike other aircraft that use tougher aluminum. Air-speed sensors - a known problem on the aircraft - failed, and could have sent conflicting data to the aircraft's computer, resulting in full throw of the sensitive rudders. At the very least, this would have made flying the aircraft very difficult, as the plane was flying in manual mode through the thunderstorms. The Airbus line has a history of both multiple rudder losses and a vertical fin and rudder separation from the airframe as was the case in NY with AA. Automated telemetry data received from the aircraft shortly before it broke up showed a failure pattern that is consistent with Boeing's conjecture. The rear fuselage has been retrieved from the ocean. Some experts claim that there is already enough evidence to put together a plausible scenario, and that the black box data would only confirm or serve as a secondary source of evidence. Nowehere in this discussion did anybody hint at a terrorist act.

#### kirknbr

I believe you’re right on with your direction. The two debris fields and the picture of that tail in one piece. My prayers go out the families of victims

#### bar1

Kestas, I don't know where you get your information, but the lastest news is that the fuselage was INTACT when it hit water. The brittle composite components you mention has been proven to be stronger than parts made in aluminium, eg. the tail section in NY with AA. That accident was pilot error. According to your logic, we will see a lot of Boeing 787 falling out of the sky soon...

#### sprintman

And I guess we better not mention B737 rudder problems killing many hundreds of people either. I can't be bothered to post it all, just search B737 rudder problems.

#### Pablo

Actually I thought the 737 rudder problems were lube related.

#### sprintman

Nope cheap design leading to rudder reversal. Boeing and the FAA refused to admit a prpblem till many hundreds of lives lost. Parker Hannafin paid out \$40m on one suit alone. Finally FAA forced a redesign and replacemt of all PFCU's some 10 years later. Still discussed daily on pilot forums, a sorry tale indeed. And I work at the airport and talk to Airbus and Boeing pilots on a daily basis (B737, A320).

#### sprintman

Update:- AF447 hit the water in one piece belly first.

#### kirknbr

was the tail still attached????

Appears so.

#### Kestas

Staff member
This is a complete reversal of earlier reports where the tail section was found 30 miles from the main fusealge wreckage. What gives?? Are you sure we aren't mixing this Airbus crash with the more recent Airbus crash? On a technical note, stength and toughness are two different things. I've been seeing a disturbing trend in recent decades where design engineers are specifying stronger materials with no regard to toughness. More and more I'm seeing brittle failures in my lab, where impact toughness is required. Plus, detecting flaws in composite materials is considerably more difficlt than with aluminum. This is important when airplanes are given the once-over or are being overhauled.

#### bar1

There is no mix. The Airbus 310 from airline Yemenia that crashed at Comoros went down when it was on it's second round trying to land. One clue to that accident: the airplane was banned in France/Europe due to lack of maintainance. AF447: The information given about the position of the tail section was probably wrong.

#### Kestas

Staff member
They still talk about two distinct debris fields separated from each other where bodies were found. Not likely if it made a belly splash.

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