Boeing
03-16-2019, 10:34 AM
#52
Registered User
OK come on, there were lots of theories about the crashes from you all, let's see some guesses about the trailing balloon or whatever it is. I don't want my post to be a thread killer.
03-16-2019, 10:50 AM
#53
I believe that is a direction indicator 
If it is behind the tail the plane is going forward. If it is in front of the tail, oops!
If it is behind the tail the plane is going forward. If it is in front of the tail, oops!
03-16-2019, 10:54 AM
#54
From aeronewstv.com
"It is in fact, the “Trailing Cone”. Present on all development aircraft during the first weeks of flight tests. The nylon cable is deployed in flight, generally 1 to 1.5 times the wing span length, or about 50 metres, behind the aircraft to measure the ambient atmospheric pressure (static pressure) precisely, in the “free-stream air-flow” outside the disrupted air-flow generated by the aircraft - a key parameter for the pilots."
"It is in fact, the “Trailing Cone”. Present on all development aircraft during the first weeks of flight tests. The nylon cable is deployed in flight, generally 1 to 1.5 times the wing span length, or about 50 metres, behind the aircraft to measure the ambient atmospheric pressure (static pressure) precisely, in the “free-stream air-flow” outside the disrupted air-flow generated by the aircraft - a key parameter for the pilots."
03-16-2019, 05:05 PM
#56
Sorry scoots I reject your theory as fake science, it's a kite tail.... 
Give it a little time and the email from some engineer's desktop form 6 years ago will pop up about how using one sensor for attitude adjustment was a stupid idea.
Or someone in supply saved $1.28 on the cost of the sensor by getting from another vendor who kept the price down by not doing testing on the parts as per the procurement drawings.
Or they painted over it or waxed over it. or someone put them through the wrong thermal test profile.
OR maybe it has nothing to do with the problems they think it is and it's bad wiring to the drive motor.
it might actually be all of those things combined.
Give it a little time and the email from some engineer's desktop form 6 years ago will pop up about how using one sensor for attitude adjustment was a stupid idea.
Or someone in supply saved $1.28 on the cost of the sensor by getting from another vendor who kept the price down by not doing testing on the parts as per the procurement drawings.
Or they painted over it or waxed over it. or someone put them through the wrong thermal test profile.
OR maybe it has nothing to do with the problems they think it is and it's bad wiring to the drive motor.
it might actually be all of those things combined.
03-17-2019, 08:12 PM
#57
Did anyone see the Smithsonian's Channel "Air Disasters," tonight? It told of Qantas Flight 72, in 2008. Airbus 330. Where the data input from sensors on the plane somehow got crossed while traveling to the main CPU. Causing the plane to automatically input pitch-down, anti-stall commands? The Australian ATSB air safety board ran this same data computer through several temp, vibration, electromagnetic interference tests and could never duplicate the error. Somehow for conditions unknown, the data feed information (angle of attack, speed, altitude, etc) gets swapped leading the CPU to think the plane is in an unsafe envelope. And reacts to correct the improper data. Apparently, this same scenario happened on other A330 planes.
ATSB and Airbus could never find the actual fault in the computer or the program. Or even the conditions likely to lead to the catastrophic information --- but, did designed more safeguards in the event misinformation data occurs. The pilot's actions saved the plane.
Excellent episode. And could explain some of the complications of Air Lion tragedy.
https://www.dailymail.co.uk/news/art...-incident.html
ATSB and Airbus could never find the actual fault in the computer or the program. Or even the conditions likely to lead to the catastrophic information --- but, did designed more safeguards in the event misinformation data occurs. The pilot's actions saved the plane.
Excellent episode. And could explain some of the complications of Air Lion tragedy.
https://www.dailymail.co.uk/news/art...-incident.html
Last edited by windhund116; 03-17-2019 at 08:16 PM.
03-17-2019, 08:34 PM
#58
For a long time at work, I was the truffle pig on those kinds of problems.
Pigs have extremely sensitive noses for truffles.
Truffles of course are a form of fungus which grows on tree roots underground.
They would train the pigs to smell out the truffles and when they started to dig for them, step in and collect the booty.
I've chased nasty problems for up to 6-8 months at a time. Sometimes really, really, hard to explain what the trigger is.
Pigs have extremely sensitive noses for truffles.
Truffles of course are a form of fungus which grows on tree roots underground.
They would train the pigs to smell out the truffles and when they started to dig for them, step in and collect the booty.
I've chased nasty problems for up to 6-8 months at a time. Sometimes really, really, hard to explain what the trigger is.
03-18-2019, 12:56 PM
#59
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The static air pressure “cone” you see behind the vertical stabilizer is used when there are modifications in the works to the static port system.
A static port is a disc about the size of an old silver dollar with a dozen or so holes drilled into it. You usually see at least 3 of them in a row in a painted rectangular box on the lower half of a fuselage. The painted box indicates a sensitive zone that should be avoided from contact on the ground and if you see anything inside the box, dents etc, it needs to be checked by a mechanic. It is critical that airflow is uniform over the static ports for accuracy. The other half of this system are the pitot tubes which measure dynamic air pressure. They are angled and protrude from the fuselage by half a foot or so. You want the intake to be outside the laminar airflow that adheres to the fuselage. I might add that you might recall observing pictures of jets in the early stages of development with a very long pitot tube sticking out in front of the nose. That is because the air in front of the plane is sure to be undisurbed. A pitot tube on a brand new airplane may deliver incorrect data so you need to be sure.
The system measures the dynamic force of air from the pitot tubes and compares it to the static pressure on the side. This generates airspeed, altitude, and rate of climb. Old reliable system. The pitot tubes are heated to prevent icing. (What happens when icing occurs is another story. Check out Northwest Orient Flt 6231 in 1974, New York)
New airspace requirements demand extremely precise navigation and altitude control: RVSM. You need that pristine static measurement hanging behind the tail to calibrate the pitot/static system.
I might add that we pilots will sometimes SLOP (Strategic Lateral Offset Procédure) on oceanic tracks- to the right of centerline- to actually reduce the probability of collision because the accuracy is so tight, a pilot error may guarantee a conflict.
A static port is a disc about the size of an old silver dollar with a dozen or so holes drilled into it. You usually see at least 3 of them in a row in a painted rectangular box on the lower half of a fuselage. The painted box indicates a sensitive zone that should be avoided from contact on the ground and if you see anything inside the box, dents etc, it needs to be checked by a mechanic. It is critical that airflow is uniform over the static ports for accuracy. The other half of this system are the pitot tubes which measure dynamic air pressure. They are angled and protrude from the fuselage by half a foot or so. You want the intake to be outside the laminar airflow that adheres to the fuselage. I might add that you might recall observing pictures of jets in the early stages of development with a very long pitot tube sticking out in front of the nose. That is because the air in front of the plane is sure to be undisurbed. A pitot tube on a brand new airplane may deliver incorrect data so you need to be sure.
The system measures the dynamic force of air from the pitot tubes and compares it to the static pressure on the side. This generates airspeed, altitude, and rate of climb. Old reliable system. The pitot tubes are heated to prevent icing. (What happens when icing occurs is another story. Check out Northwest Orient Flt 6231 in 1974, New York)
New airspace requirements demand extremely precise navigation and altitude control: RVSM. You need that pristine static measurement hanging behind the tail to calibrate the pitot/static system.
I might add that we pilots will sometimes SLOP (Strategic Lateral Offset Procédure) on oceanic tracks- to the right of centerline- to actually reduce the probability of collision because the accuracy is so tight, a pilot error may guarantee a conflict.