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Massive Test Probe On 741  
User currently offlineJHSfan From Denmark, joined Apr 2004, 469 posts, RR: 2
Posted (8 years 2 months 3 weeks 3 days 18 hours ago) and read 2485 times:

On h.. of a massive probe - Why?

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I suppose that Boeing wanted data from a point forward of the plane, a point where the air is still relatively "untouched" by the flying plane.
Someone must have an idea of why, thanks.

Yours in realtime
JHSFan


Look at me, I´m riding high, I´m the airbornmaster of the sky...
12 replies: All unread, jump to last
 
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 1, posted (8 years 2 months 3 weeks 3 days 18 hours ago) and read 2455 times:

When the pitot tube probe is placed far ahead of the aircraft, it is much less prone to installation error (and, as a matter of fact, helps the engineers determine what the installation error is on the final placement of the pitot tube  Wink ). Also, many flight test articles contain Angle-of-Attack instrumentation in the long test boom (extremely useful data for flight testing!).


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 2, posted (8 years 2 months 3 weeks 3 days 17 hours ago) and read 2439 times:

The "massive" probe size was to diffuse the aerodynamic stress placed on the nose by such a long probe. Much like the Eiffel tower having a wider base than tip.
 Smile



One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17173 posts, RR: 66
Reply 3, posted (8 years 2 months 3 weeks 3 days 16 hours ago) and read 2389 times:

Well, the particular 747 had just seen a very cute 727 passing on the taxiway and couldn't control himself at this early hour...


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineJamesbuk From United Kingdom, joined May 2005, 3968 posts, RR: 4
Reply 4, posted (8 years 2 months 3 weeks 3 days 15 hours ago) and read 2382 times:

"I'm a real plane!!". " whys my nose growing, i am real i am!"

but seriously im guessing that it has test equipment in it, maybe to test pressures and stuff before it hits the plane.

Rgds --James--



You cant have your cake and eat it... What the hells the point in having it then!!!
User currently offline777WT From United States of America, joined Jan 2005, 877 posts, RR: 1
Reply 5, posted (8 years 2 months 3 weeks 3 days 14 hours ago) and read 2354 times:

It's an flying dart!  Wink

Notice the tech dragging his toolbox on wheels?


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17173 posts, RR: 66
Reply 6, posted (8 years 2 months 3 weeks 3 days 13 hours ago) and read 2335 times:

Quoting 777WT (Reply 5):
Notice the tech dragging his toolbox on wheels?

Early roll-aboard! Big grin



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineJHSfan From Denmark, joined Apr 2004, 469 posts, RR: 2
Reply 7, posted (8 years 2 months 3 weeks 3 days 2 hours ago) and read 2245 times:

Quoting Avioniker (Reply 2):
The "massive" probe size was to diffuse the aerodynamic stress placed on the nose by such a long probe. Much like the Eiffel tower having a wider base than tip

You are probably right about that, but it's not an absolute necessity.

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These two former enemy-planes shows that a tube pointing forward does not need to have a very thick connection to the fuselage.

If you take a look just below the headlight on the nose of the Nimrod, you will see a smaller version of the 741 probe. The shape is conical as the the bigger Boeing, yet size is different.

This Boeing plane has the same type of test probe:

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Boeing or maybe NASA must have fancied that shape for tests. Right now i'm looking for more info on the net about the USAF/NASA plane.

Quoting KELPkid (Reply 1):

It sound like you are making a point, thanks KELPkid.

One final note (so far) to those of you who make fun of the poor plane. Everyone thinks that it's a Pan Am plane just because it seems that way - blue and white with a visible letter "P" just like the Pan Am plane in the middle.
Naturally Pan Am would not like to have their name om such a weird looking plane. So I thinks that Boeing must have painted Pinocchio on the fuselage instead. Big grin

Yours in realtime
JHSfan



Look at me, I´m riding high, I´m the airbornmaster of the sky...
User currently offlineOly720man From United Kingdom, joined May 2004, 6843 posts, RR: 11
Reply 8, posted (8 years 2 months 3 weeks 3 days ago) and read 2222 times:

Quoting JHSfan (Reply 7):
Right now i'm looking for more info on the net about the USAF/NASA plane.

It was used in the early 1980's for winglet research. In the db there is a side view of the aircraft on the same day and the remark mentions it having winglets on. The nose probe was presumably to get accurate attitude information to correlate the winglet results.

This is a review of the tests..... It's huge >30Mb, 192 pages.

http://ntrs.nasa.gov/archive/nasa/ca...asa.gov/19840019618_1984019618.pdf



The probe will be conical for structural rigidity so the pitch and yaw probe angles measured at the tip can be relied upon. It doesn't really matter if refuelling probes bounce around a bit.


edit : added photo - go to NASA dryden multimedia to see others

[Edited 2006-09-29 13:39:07]


wheat and dairy can screw up your brain
User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 9, posted (8 years 2 months 3 weeks 2 days 23 hours ago) and read 2197 times:

The taper shape also allowes the boom to flow into the radome attach points used to secure the structure to the nose. The refuelling booms are attached to fuselage hard points so don't need the taper.
 Smile



One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 10, posted (8 years 2 months 3 weeks 2 days 22 hours ago) and read 2171 times:

Quoting JHSfan (Thread starter):
I suppose that Boeing wanted data from a point forward of the plane, a point where the air is still relatively "untouched" by the flying plane.
Someone must have an idea of why, thanks.

JHSfan, Your are correct, the probe is called a "Gust Boom" it allows turbulence to be measured without interference from the airframe.


User currently offlineJHSfan From Denmark, joined Apr 2004, 469 posts, RR: 2
Reply 11, posted (8 years 2 months 3 weeks 1 day 22 hours ago) and read 2029 times:

Thanks a lot for your explanations.  Smile

It seems that gust booms has been replaced by a radar based wind-gust system.

- JHSfan



Look at me, I´m riding high, I´m the airbornmaster of the sky...
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12181 posts, RR: 51
Reply 12, posted (8 years 2 months 3 weeks 1 day 2 hours ago) and read 1929 times:

The boom gathers very accurate TAS (true airspeed) information. A second method to get accurate TAS is to trail a small drogue off the tip of the vertical stabilzer. But, the boom can be used to get additional information, as already has been mentioned.

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