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Probes On Nose Of A350XWB  
User currently offlinehivue From United States of America, joined Feb 2013, 1112 posts, RR: 0
Posted (1 year 7 months 1 week 1 day 5 hours ago) and read 9080 times:

I tried this over on the civ av forum and got no bites, so I thought I would try it here.

http://www.airbus.com/fileadmin/medi.../A350_XWB_paint_shop_rollout_8.jpg

There are 12 probes clustered around the nose. Air data I assume, AoA vanes maybe, maybe some others. Are some of these only for test? I haven't seen anything that looks like a pitot tube anywhere else on the fuselage in the AB photos. WiIl this be the final home for all these probes on the production aircraft? Can anybody name all of 12 of the probes?

26 replies: All unread, showing first 25:
 
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 1, posted (1 year 7 months 1 week 1 day 3 hours ago) and read 9026 times:

I wish we could get a a better angle. These help a bit: http://www.airbus.com/fileadmin/medi.../A350_XWB_paint_shop_rollout_7.jpg
http://www.airbus.com/fileadmin/medi.../A350_XWB_paint_shop_rollout_9.jpg


My very wild arsed guesses going clockwise from bottom left to bottom right and ignoring the static ports (in the flat areas).
1. OAT probe.
2. AoA vane.
3. AoA vane.
4. (in middle group). Pitot.
5. Test article for airflow measurement?
6. Test article for airflow measurement?
7. Test article for airflow measurement?
8. Pitot.
9. ?
10. AoA vane.
11. Test article for airflow measurement?
12. OAT probe.

[Edited 2013-05-14 17:31:44]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinehivue From United States of America, joined Feb 2013, 1112 posts, RR: 0
Reply 2, posted (1 year 7 months 1 week 1 day 3 hours ago) and read 9004 times:

Quoting Starlionblue (Reply 1):

Thanks.

Yes, I should have linked to photos on both sides.

Is this arrangement unusually close tgether? It looks like a single bird strike could take out 2 AoA vanes.

I assume one pitot is the captain's and one is the FO's? So there must be another one somewhere else for the standby system?


User currently onlineGlobalMoose From United States of America, joined Aug 2012, 33 posts, RR: 0
Reply 3, posted (1 year 7 months 1 week 1 day 3 hours ago) and read 8990 times:

Continuing the numbering convention:

1. Icing probe
2. AoA vane
3. AoA vane
4. OAT(SAT)/RAT probe
5. AoA vane
6. AoA vane
7. AoA vane
8. OAT(SAT)/RAT probe
9. Pitot probe
10. AoA vane
11. AoA vane
12. Pitot probe

All a best guess - for the following reasons:

I'm used to seeing Items equally and oppositely divided on either side of the A/C which makes me wonder about my guess about the pitot probe

1. Looks like what we use in our jet and what is on the 744 (just prior to the wipers). It is a little piece of metal that vibrates (or doesn't, unsure) when ice builds up on it (pilot rumor)
2. Multiple AoA vanes - they look like they move around, just like an AoA vane would
4. Looks just like what we have on our jet (and this time I have been face to face with the probe and have read the labels on it)
9, 12. long, slender, tubular item with a hole in the front - looks like a pitot probe - but a bit confused as why they are only on one side.

We need an engineer - pilots only know so much (and usually specialize in how to break their jets!)



When it absolutely positively has to be there ... at some point.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 4, posted (1 year 7 months 1 week 1 day 3 hours ago) and read 8987 times:

I think GlobalMoose's guesses are much better than mine.

Quoting GlobalMoose (Reply 3):
5. AoA vane
6. AoA vane
7. AoA vane

I think you are right in that they are airflow vanes, but I don't think they measure AoA due to location.

Quoting hivue (Reply 2):
Is this arrangement unusually close tgether? It looks like a single bird strike could take out 2 AoA vanes.

You'd still have the ones on the other side. Also some of these probes may do double duty.

Quoting hivue (Reply 2):
I assume one pitot is the captain's and one is the FO's? So there must be another one somewhere else for the standby system?

I don't know about the 350 but many large airliners have four pitots and four static ports, plus two standby static ports.

[Edited 2013-05-14 17:56:26]

[Edited 2013-05-14 17:58:53]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinehivue From United States of America, joined Feb 2013, 1112 posts, RR: 0
Reply 5, posted (1 year 7 months 1 week 1 day 2 hours ago) and read 8966 times:

Quoting GlobalMoose (Reply 3):
I'm used to seeing Items equally and oppositely divided on either side of the A/C
Quoting Starlionblue (Reply 4):
Quoting GlobalMoose (Reply 3):5. AoA vane
6. AoA vane
7. AoA vane
I think you are right in that they are airflow vanes, but I don't think they measure AoA due to location.

So it sounds like this probe composition/arrangement may be special for the flight test campaign and is not intended to be the same as what will be on the production aircraft.


User currently offlinePihero From France, joined Jan 2005, 4667 posts, RR: 77
Reply 6, posted (1 year 7 months 1 week 1 day 1 hour ago) and read 8935 times:
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Quoting Starlionblue (Reply 1):
from bottom left to bottom right

Difficult  
Things have changed a bit these modern days :

Right side, from top to bottom :
- 2 MFPs, multi-function probes, they integrate Total Pressure / TAT / AoA sensors for ADIRUs 2 and 3
- 1 Pitot ( probably for tests as the usual Airbus STBY pitot is on port side )

Top of the nose, excluding the - you were right - ice detectors (2 electrical / 2 visual ), from left to right :
- 1 Pitot (Test I'd guess )
- 3 SSA probes ( side-slip angle, one for each ADIRU )
- 1 Pitot ( Test I'd guess )

Left side from top to bottom :
- 1 STBY Pitot ( for ISIS )
- 1 MFP for ADIRU 1
- 1 AoA sensor ( Test I'd guess )
- 1 TAT ( Test I'd guess )

( my best effort )



Contrail designer
User currently offlineboeingfixer From Canada, joined Jul 2005, 534 posts, RR: 0
Reply 7, posted (1 year 7 months 1 week 12 hours ago) and read 8662 times:

Here's my take on the probes.

Looking at the photo and going clockwise from lower left.

1. Ice Detector
2. Multi-Function Probe
3. Multi-Function Probe
4. TAT Probe
5 thru 7. Side Slip Vanes
8. TAT Probe
9. Pitot Probe
10. Multi-Function Probe
11. AOA Vane
12. Ice Detector

Cheers,

John



Cheers, John YYC
User currently onlineGlobalMoose From United States of America, joined Aug 2012, 33 posts, RR: 0
Reply 8, posted (1 year 7 months 1 week 10 hours ago) and read 8597 times:

Quoting Starlionblue (Reply 4):
I think you are right in that they are airflow vanes, but I don't think they measure AoA due to location.

Makes perfect sense - you kind of need the AoA vanes to be oriented along the longitudinal axis and able to pivot up and down, not side to side!



When it absolutely positively has to be there ... at some point.
User currently offlineairmagnac From Germany, joined Apr 2012, 321 posts, RR: 52
Reply 9, posted (1 year 7 months 1 week 10 hours ago) and read 8584 times:

Quoting boeingfixer (Reply 7):

1. Ice Detector
2. Multi-Function Probe
3. Multi-Function Probe
4. TAT Probe
5 thru 7. Side Slip Vanes
8. TAT Probe
9. Pitot Probe
10. Multi-Function Probe
11. AOA Vane
12. Ice Detector

I agree with your take
Numbers 4 and 7 have big rectangular intakes which look more like TAT probes than pitot probes. Especially when compared to the stand-by pitot (nbr 9)
1 and 12 I'm not too sure, but they look the same. I'll go along with your idea of ice detectors

Wonder if the red markings may be a clue to indicate which ones are series probes and which are test probes   



One "oh shit" can erase a thousand "attaboys".
User currently offlinePihero From France, joined Jan 2005, 4667 posts, RR: 77
Reply 10, posted (1 year 7 months 1 week 9 hours ago) and read 8565 times:
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Quoting GlobalMoose (Reply 8):
Quoting Starlionblue (Reply 4):
I think you are right in that they are airflow vanes, but I don't think they measure AoA due to location.

Makes perfect sense - you kind of need the AoA vanes to be oriented along the longitudinal axis and able to pivot up and down, not side to side!

That's why they are Side Slip Angle sensors

Quoting boeingfixer (Reply 7):
and going clockwise from lower left.

We need to agree on what we're talking about here : if you go clockwise from lower left, you go under the belly if you're an outside observer looking at the aircraft facing the nose.

I now stand by my first post... but I could be wrong. As a matter of fact, my only hesitation is on your #1, which IMO is a TAT probe reference for the top of the nose probes and could be, as Boeingfixer thinks an icing detector.

The most accurate view on this side comes from the rollout video.
http://www.youtube.com/watch?v=X61QDi1zEyQ
Starting at time .30 seconds, we see the left side probes : the difference between the MFP and the AoA ; The top pitot is clearly visible and the recognisable TAT probe at bottom.



Contrail designer
User currently offlineairmagnac From Germany, joined Apr 2012, 321 posts, RR: 52
Reply 11, posted (1 year 7 months 1 week 6 hours ago) and read 8474 times:

I haven't worked on air data probes for a few years, so technology might have moved on, but I remember the TAT probes being like pitot probes with bigger rectangular intakes ? After all, they perform a similar function of isentropic deceleration
Which is why I'd rather go for TAT sensors on either side of the SSA vanes on the nose. Or maybe some kind of MFP without the moving vane part (so just Pt and Tt measurement) ?

As for the 2 things on the bottom on either side, they look very much like the 2 on either side of the SSA vanes on the A380 :
http://www.airliners.net/photo/China...d=98b7e08c309196cadf158b50416d1042

In that view, the sensors really remind me of temperature sensors used in internal ductings. So maybe SAT/OAT probes ?



One "oh shit" can erase a thousand "attaboys".
User currently offlinePihero From France, joined Jan 2005, 4667 posts, RR: 77
Reply 12, posted (1 year 7 months 1 week 5 hours ago) and read 8426 times:
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Quoting airmagnac (Reply 11):
As for the 2 things on the bottom on either side, they look very much like the 2 on either side of the SSA vanes on the A380

These are the A380 ice detectors.

Quoting airmagnac (Reply 11):
Which is why I'd rather go for TAT sensors on either side of the SSA vanes on the nose.

I'd agree but that would make it 3 MFP + 1 TAT (left side ) + 2 TAT (top of nose ) = 6 TAT measurements, which seems to me rather a lot... on the other hand, I can't find any static ports associated with them. Those visible - 3 aligned on both sides of the fuselage belong to the ADIRUS, the two symetrically positioned under the cockpit windscreen are for the ISIS, so I'm for a search for aerodynamic data on this nose area.
(Based on previous Airbus solutions, the 380 in particular.

Quoting airmagnac (Reply 11):
So maybe SAT/OAT probes ?

they measure TAT and compute OAT

Quoting boeingfixer (Reply 7):
1. Ice Detector
Quoting boeingfixer (Reply 7):
12. Ice Detector

Possible, but IMO, they are on top of the nose, under the windscreen. ( the center ones )



Contrail designer
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 13, posted (1 year 7 months 1 week 3 hours ago) and read 8402 times:

Quoting Pihero (Reply 10):
Quoting boeingfixer (Reply 7):
and going clockwise from lower left.

We need to agree on what we're talking about here : if you go clockwise from lower left, you go under the belly if you're an outside observer looking at the aircraft facing the nose.

The confusion is was my fault. My nomenclature was clockwise from lower left from the viewpoint of the observer in the picture, not relative to the aircraft. Should have been clear about that.

  



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineairmagnac From Germany, joined Apr 2012, 321 posts, RR: 52
Reply 14, posted (1 year 7 months 6 days 21 hours ago) and read 8324 times:

Quoting Pihero (Reply 12):
Je me coucherai moins bête ce soir, thanks !



One "oh shit" can erase a thousand "attaboys".
User currently offlineboeingfixer From Canada, joined Jul 2005, 534 posts, RR: 0
Reply 15, posted (1 year 7 months 6 days 4 hours ago) and read 8088 times:

Quoting Pihero (Reply 10):
We need to agree on what we're talking about here : if you go clockwise from lower left, you go under the belly if you're an outside observer looking at the aircraft facing the nose.

My list was from the viewpoint of the photo.

Quoting Pihero (Reply 10):
I now stand by my first post... but I could be wrong. As a matter of fact, my only hesitation is on your #1, which IMO is a TAT probe reference for the top of the nose probes and could be, as Boeingfixer thinks an icing detector.

TAT probes and Ice Detector probes look and function totally different from each other. I don't "think" 1 and 12 are Ice Detectors, I "know" they are Ice Detectors. I've learned a bit after 23 years as a mechanic on transport category aircraft.  
Quoting Pihero (Reply 12):
Quoting airmagnac (Reply 11):
As for the 2 things on the bottom on either side, they look very much like the 2 on either side of the SSA vanes on the A380

These are the A380 ice detectors.

They are indeed Ice Detectors and are the same as those in position 1 and 12 on the A350.

Quoting Pihero (Reply 12):
Quoting boeingfixer (Reply 7):
1. Ice Detector
Quoting boeingfixer (Reply 7):
12. Ice Detector

Possible, but IMO, they are on top of the nose, under the windscreen. ( the center ones )

Those items right under the windscreen are for the windshield wipers which have yet to be installed.

Quoting Pihero (Reply 12):
I'd agree but that would make it 3 MFP + 1 TAT (left side ) + 2 TAT (top of nose ) = 6 TAT measurements,

Correct me if I'm wrong but I thought the MFP's only measured AOA, Total Pressure and Static Pressure. This would leave only the 2 TAT probes outboard of the SSA Vanes.

Cheers,

John



Cheers, John YYC
User currently offlinePihero From France, joined Jan 2005, 4667 posts, RR: 77
Reply 16, posted (1 year 7 months 6 days 3 hours ago) and read 8073 times:
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Quoting boeingfixer (Reply 15):

Correct me if I'm wrong but I thought the MFP's only measured AOA, Total Pressure and Static Pressure.

No : they measure Pt / TAT / AoA . The static ports for the ADIRUS are aligned on the lower part of the fuselage, further back.

Quoting boeingfixer (Reply 15):

They are indeed Ice Detectors and are the same as those in position 1 and 12 on the A350.

After having managed to enlarge the pics, I now think you're right. The video I linked apparently shows a shadow.
Mea culpa !

Quoting boeingfixer (Reply 15):

Those items right under the windscreen are for the windshield wipers which have yet to be installed.

See this Goodrich description of their product :
Ice detection probe
As for the wipers, you're right, they are missing, but which ones of the six ?



Contrail designer
User currently offlineboeingfixer From Canada, joined Jul 2005, 534 posts, RR: 0
Reply 17, posted (1 year 7 months 5 days 8 hours ago) and read 7868 times:

Quoting Pihero (Reply 16):
Quoting boeingfixer (Reply 15):

Correct me if I'm wrong but I thought the MFP's only measured AOA, Total Pressure and Static Pressure.

No : they measure Pt / TAT / AoA . The static ports for the ADIRUS are aligned on the lower part of the fuselage, further back.

Thanks for the info. Just found the patent here: MFP Patent PDF

Also a good photo of the MFP here: Multi Function Probe

I would hazard a guess that the extra 2 TAT probes are for flight test instrumentation.

Quoting Pihero (Reply 16):
Quoting boeingfixer (Reply 15):

Those items right under the windscreen are for the windshield wipers which have yet to be installed.

See this Goodrich description of their product :
Ice detection probe
As for the wipers, you're right, they are missing, but which ones of the six ?

Only the front windscreens have the wipers. The two large protrusions at the centre below the front windscreens are the posts that the wiper arms attach to. The two posts that protrude at the centre of the lower frames are Ice Detectors as well. Same thing as on the A380 HERE

Cheers,

John



Cheers, John YYC
User currently offlineSlcpilot From United States of America, joined Aug 2003, 592 posts, RR: 2
Reply 18, posted (1 year 7 months 4 days 9 hours ago) and read 7666 times:

I was kinda hoping the same technology that allows the G650 to be in service without wipers might have made it to the A-350. It would certainly make for a quieter flight deck! I'm looking forward to this becoming more commonplace.

Also, it would be neat if the B-2s air data system could also make it into the civilian world. It doesn't have any probes/vanes, does it?

Cheers!

SLCPilot



I don't like to be fueled by anger, I don't like to be fooled by lust...
User currently offlineKlaus From Germany, joined Jul 2001, 21521 posts, RR: 53
Reply 19, posted (1 year 7 months 3 days 4 hours ago) and read 7476 times:

Quoting Slcpilot (Reply 18):
I was kinda hoping the same technology that allows the G650 to be in service without wipers might have made it to the A-350. It would certainly make for a quieter flight deck! I'm looking forward to this becoming more commonplace.

How does that work?


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 20, posted (1 year 7 months 2 days 23 hours ago) and read 7429 times:

Quoting Slcpilot (Reply 18):
Also, it would be neat if the B-2s air data system could also make it into the civilian world. It doesn't have any probes/vanes, does it?

True, but the "pitot plates" are for low observability purposes. The fact that it uses non protruding sensors doesn't make it better for civilian applications I bet the B-2 systems are both more expensive and less reliable than the systems on airliners.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineSlcpilot From United States of America, joined Aug 2003, 592 posts, RR: 2
Reply 21, posted (1 year 7 months 2 days 15 hours ago) and read 7333 times:

It seems it's some sort of water repelling surface....

http://www.ppg.com/en/newsroom/news/Pages/20090408.aspx

The design for the heated glass windshields will be a carryover from the G550 jet, with Surface Seal water-repellent coating by PPG as the primary rain-removal system to enable Gulfstream to certify the aircraft without windshield wipers, which increase drag and weight.



I don't like to be fueled by anger, I don't like to be fooled by lust...
User currently offlineSlcpilot From United States of America, joined Aug 2003, 592 posts, RR: 2
Reply 22, posted (1 year 7 months 2 days 15 hours ago) and read 7326 times:

Quoting Starlionblue (Reply 20):
True, but the "pitot plates" are for low observability purposes. The fact that it uses non protruding sensors doesn't make it better for civilian applications I bet the B-2 systems are both more expensive and less reliable than the systems on airliners.

True, most designs are limited by a cost/benefit trade study. Let me share two personal experiences.

First, in the type of plane I most often fly now, the flight deck noise is often distinguished by which generation of wiper blade arms are installed. It makes one wonder what it would be like with NO wiper blades!

Second. In the Falcon 20 the wipers retract into a slot in front of the windscreen. On one particularly cold snowy night, the melting snow accumulated as ice in the slot due to a frozen drain hole. When the chuck of ice left shortly after takeoff, it became FOD for #1 and resulted in total thrust loss (we kept it running for hydraulic power), and an emergency declaration. It was not a fun evening.

With today's modern, miniature, inexpensive (not for certified airplanes, granted) electronics and sensors, I am a little surprised our aircraft are still littered with probes, detectors, vanes, antennas, etc! !

Fly Safe!

SLCPilot



I don't like to be fueled by anger, I don't like to be fooled by lust...
User currently offlineKlaus From Germany, joined Jul 2001, 21521 posts, RR: 53
Reply 23, posted (1 year 7 months 2 days 12 hours ago) and read 7286 times:

Quoting Slcpilot (Reply 21):
The design for the heated glass windshields will be a carryover from the G550 jet, with Surface Seal water-repellent coating by PPG as the primary rain-removal system to enable Gulfstream to certify the aircraft without windshield wipers, which increase drag and weight.

Thanks.


User currently offlineketa From Germany, joined Mar 2005, 448 posts, RR: 0
Reply 24, posted (1 year 6 months 1 week 8 hours ago) and read 6039 times:

Talking about probes, I saw that it has what looks like a huge red pitot tube on the left horizontal stabilizer:


View Large View Medium
Click here for bigger photo!

Photo © Mike Stewart


View Large View Medium
Click here for bigger photo!

Photo © T.Laurent




Where there's a will, there's a way
25 Klaus : From the location I would guess it's more for wing and engine effects observation (turbulent flow / local angle of attack).
26 Post contains links and images Viscount724 : DC-8s have been flying without wipers since 1959. They have some type of "rain removal system" using bleed air. View Large View MediumPhoto © Erik B
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