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String Hanging From A380 Tail  
User currently offlineJawed From United States of America, joined Sep 2006, 482 posts, RR: 0
Posted (8 years 3 weeks 6 days 3 hours ago) and read 7258 times:

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

18 replies: All unread, jump to last
 
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 1, posted (8 years 3 weeks 6 days 3 hours ago) and read 7245 times:

Part of the test flight monitoring equipment


"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 2, posted (8 years 3 weeks 5 days 16 hours ago) and read 7123 times:

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.


User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 3, posted (8 years 3 weeks 5 days 14 hours ago) and read 7079 times:

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



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 4, posted (8 years 3 weeks 5 days 14 hours ago) and read 7076 times:

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


User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 5, posted (8 years 3 weeks 5 days 12 hours ago) and read 7031 times:

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]

User currently offlineJamesbuk From United Kingdom, joined May 2005, 3968 posts, RR: 4
Reply 6, posted (8 years 3 weeks 5 days 11 hours ago) and read 6997 times:

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--



You cant have your cake and eat it... What the hells the point in having it then!!!
User currently offlineBuyantUkhaa From Mongolia, joined May 2004, 2915 posts, RR: 3
Reply 7, posted (8 years 3 weeks 5 days 7 hours ago) and read 6934 times:

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



I scratch my head, therefore I am.
User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 8, posted (8 years 3 weeks 4 days 22 hours ago) and read 6868 times:

Test Probe for the P/S system.
regds
MEL



Think of the brighter side!
User currently offlineLegoguy From United Kingdom, joined Jun 2006, 3314 posts, RR: 39
Reply 9, posted (8 years 3 weeks 4 days 9 hours ago) and read 6698 times:

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


Can you say 'Beer Can' without sounding like a Jamaican saying 'Bacon'?
User currently offlinePygmalion From United States of America, joined Jun 2006, 969 posts, RR: 37
Reply 10, posted (8 years 3 weeks 4 days 7 hours ago) and read 6674 times:

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.

User currently offlineJerald01 From United States of America, joined Oct 2006, 161 posts, RR: 2
Reply 11, posted (8 years 3 weeks 4 days 6 hours ago) and read 6665 times:

 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 



"There may be old pilots, and there may be bold pilots, but there are darn few green cows"
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 12, posted (8 years 3 weeks 3 days 5 hours ago) and read 6607 times:

So does it only hang out the couple of feet as seen in the pics, or can it be extended further out?

User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 13, posted (8 years 3 weeks 3 days 5 hours ago) and read 6605 times:

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.


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3598 posts, RR: 66
Reply 14, posted (8 years 3 weeks 1 day 3 hours ago) and read 6479 times:

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.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 15, posted (8 years 3 weeks 9 hours ago) and read 6405 times:

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



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineRedFlyer From United States of America, joined Feb 2005, 4376 posts, RR: 28
Reply 16, posted (8 years 3 weeks 2 hours ago) and read 6365 times:

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?



My other home is a Piper Cherokee 180C
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17173 posts, RR: 66
Reply 17, posted (8 years 2 weeks 6 days 21 hours ago) and read 6335 times:

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.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePygmalion From United States of America, joined Jun 2006, 969 posts, RR: 37
Reply 18, posted (8 years 1 week 3 days 7 hours ago) and read 6167 times:

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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