Jawed
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String Hanging From A380 Tail

Sun Nov 26, 2006 12:59 pm

What is this weird string hanging from the rear tip of the A380's vertical stabilizer?

http://news.yahoo.com/photo/061125/p...p/bbee4c587659311b20374b2e48b5b23e
 
EMBQA
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RE: String Hanging From A380 Tail

Sun Nov 26, 2006 1:32 pm

Part of the test flight monitoring equipment
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N231YE
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 12:12 am

It is part of the test flight monitoring equipment. There are some pictures of the 777 with this device attached also, as shown here; the 777-200LR.



It basically consists of a cable (possibly carrying data), along with a large fibreglass cone that protects the instruments inside. Supposedly, the equipment on this device is actually more accurate than the aircraft's own instruments, hence why it is used.
 
FredT
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 1:56 am

It's a trailing-cone static pressure probe. Gives you a static pressure without the disturbances associated with static ports on the fuselage.

No electronics in the ones I've been in contact with. It's just a tube connecting it to the aircraft, no wire.

Rgds,
/Fred
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474218
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 2:00 am

Its called a "trailing cone". It is used to set up the pitot static system (speed and altitude). It can be extended during flight to get measurements that are not effected by the aircrafts wake.

http://www.spaceagecontrol.com/s002b.htm
 
N231YE
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 4:22 am

Quoting FredT (Reply 4):
No electronics in the ones I've been in contact with. It's just a tube connecting it to the aircraft, no wire.

Thank you for clearing that up. I was not sure if there were sensors that changed the pressure data to an electronic signal sent via wire or wireless, but as you have said, it is just a long tube-no electronics needed.

[Edited 2006-11-26 20:25:21]
 
jamesbuk
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 5:45 am

Basically on the A380 what it was, is they are suffering with the same climb rate as the A340's, As it took off it just couldnt get up! it flew through a fence and into a kids birthday party, poor kid was sucked in and some balloons got stuck to the tail.

 Wink

Seriously i understand its to calibrate the Pitot tubes and other delicate equipment.

Rgds --James--
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Buyantukhaa
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 9:46 am

Quoting Jamesbuk (Reply 7):
it flew through a fence and into a kids birthday party, poor kid was sucked in and some balloons got stuck to the tail

Sick but funny Big grin
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HAWK21M
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RE: String Hanging From A380 Tail

Mon Nov 27, 2006 6:09 pm

Test Probe for the P/S system.
regds
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legoguy
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RE: String Hanging From A380 Tail

Tue Nov 28, 2006 7:37 am

There is a picture floating around somewhere of the 'other end of the string' which is at the black of the aircraft attached to a little pulley which measures the forces IIRC
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pygmalion
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RE: String Hanging From A380 Tail

Tue Nov 28, 2006 9:38 am

Most have it right... its a trailing static probe. Its a 100-200 foot long hose. (long enough to get out of the aircraft wake field, it trails above most of the wake) The cone on the end is just to pull it out straight. The actual probe is about 4-6 feet in front of that cone. Its used to calibrate the pitot static probe system on all new aircraft. The static ports on the skin near the nose are affected somewhat by both angle of attack and by yaw angle of the airplane. The probe trailing far enough behind the airplane is unaffected by aircraft attitude. You can compare the airplane static pressure reading to the trailing probe to validate the location of the static probes and provide the air data computers with correction data for use in service. This is part of any new aircraft flight test program. I was did this for the Piper Turbo Malibu flight test program. There was a incident where a flight test aircraft drug the probe though the fence at the airport when it landed because the retraction reel broke in flight.
 
Jerald01
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RE: String Hanging From A380 Tail

Tue Nov 28, 2006 10:11 am

 sorry  My previous post about this device got kicked off the forum because it was "off topic". The device in question is, indeed, a trailing static probe, a device used to check various atmospheric conditions around the aircraft while it is being test flown. Many posters have correctly stated it's form and function.

I still maintain it "could" be used to snare potential customers, but I won't.........  mischievous 
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Fly2HMO
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RE: String Hanging From A380 Tail

Wed Nov 29, 2006 10:55 am

So does it only hang out the couple of feet as seen in the pics, or can it be extended further out?
 
474218
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RE: String Hanging From A380 Tail

Wed Nov 29, 2006 11:07 am

Quoting FLY2HMO (Reply 12):
So does it only hang out the couple of feet as seen in the pics, or can it be extended further out?

It can be let out to trail further behind the aircarft at cruse.
 
OldAeroGuy
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RE: String Hanging From A380 Tail

Fri Dec 01, 2006 1:33 pm

Quoting FredT (Reply 3):
No electronics in the ones I've been in contact with. It's just a tube connecting it to the aircraft, no wire.

You're correct about no electronics, but there is a wire. The tubing is supported by a cable that provides the necessary strength for high speed flying.

Even with the cable, it's not uncommon for the whole apparatus to be lost in flight.
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FredT
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RE: String Hanging From A380 Tail

Sat Dec 02, 2006 7:03 am

Quoting OldAeroGuy (Reply 14):
You're correct about no electronics, but there is a wire. The tubing is supported by a cable that provides the necessary strength for high speed flying.

There's always a catch...  Wink
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redflyer
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RE: String Hanging From A380 Tail

Sat Dec 02, 2006 1:54 pm

Quoting Pygmalion (Reply 10):
You can compare the airplane static pressure reading to the trailing probe to validate the location of the static probes and provide the air data computers with correction data for use in service.

Why would the 777LR pictured in Reply #2, above, need to have this probe? Wouldn't Boeing already have the required calibration information from earlier models of the 777?
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Starlionblue
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RE: String Hanging From A380 Tail

Sat Dec 02, 2006 7:18 pm

Quoting RedFlyer (Reply 16):
Why would the 777LR pictured in Reply #2, above, need to have this probe? Wouldn't Boeing already have the required calibration information from earlier models of the 777?

There is a new certification required for this model. The certification process is not as comprehensive as for the original 777, since as you say that's already been done, but apparently new data is needed.

Speculation follows: The combination of raked wingtips and the new engines does something new with airflow. If nothing else, the pitot static system must be precisely calibrated to give accurete airspeed.
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pygmalion
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RE: String Hanging From A380 Tail

Wed Dec 13, 2006 9:24 am

Its not that the calibration changed its that you have to prove it didn't change. A part of the "equation" is that the trailing static line is much more accurate at high angles of attack or yaw angles. etc.. i.e. flight test attitudes. The regular pitot static probes are affected by changes in airflow around the nose by the nose not being aligned with the airstream.

Also, having a reference to an accurate static source helps provide accuracy to the flight test data where the aircraft one might be drifting from air buffet etc..

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