AA's new 777 has a hump above the 2nd door. In searching the database, I don't see it on other T7. Anyone know the purpose?

http://www.airliners.net/photo/Untit...ines)/Boeing-777-323/ER/2206826/L/

Satellite dish for internet?

Quoting btfarrwm (Thread starter): AA's new 777 has a hump above the 2nd door. In searching the database, I don't see it on other T7. Anyone know the purpose?

Satellite dish for internet?

Its probably for Wifi comms equipment. I'm pretty sure I read these aircraft have it installed and I've seen similar "humps" on other WiFi equipped aircraft (WN B73G's, DL etc.)

Wifi like others have said.

2 of Etihad's most recent 77W's have the same wifi dome that the AA 77W has.

http://www.airliners.net/photo/Untit...ways)/Boeing-777-3FX-ER/2204097/L/

http://www.airliners.net/photo/Untit...ways)/Boeing-777-3FX-ER/2202481/L/

The WiFi of Notre Dame.  

It a 748I hybrid...      

Panasonic eXConnect

http://www.mascorp.com/products/globalcomm.aspx

The title was a bit misleading 

I Thought someone had joined the Mile High Club !!         

Cheers

Scandinavian Airlines has it long time ago..

http://www.airliners.net/photo/Scand...d=14e1731c2e4bcd0dd56782098bc74d15

http://www.airliners.net/photo/Scand...d=14e1731c2e4bcd0dd56782098bc74d15

Quoting btfarrwm (Thread starter): AA's new 777 has a hump above the 2nd door. In searching the database, I don't see it on other T7. Anyone know the purpose?

I don't know how old TC-JJI is but it sure looks like it have one too

Out of curiosity, what kind of drag/fuel penalty does the bump and extra weight typically put on an aircraft? I can't find any info on that.

Quoting YVRFlyer (Reply 11): Out of curiosity, what kind of drag/fuel penalty does the bump and extra weight typically put on an aircraft? I can't find any info on that.

great question, I'd like to know as well..............

Quoting YVRFlyer (Reply 11): Out of curiosity, what kind of drag/fuel penalty does the bump and extra weight typically put on an aircraft? I can't find any info on that.

Haven't heard specifics about this aircraft/system, but Virgin Australia has a similar antenna installed on many of its 737s that had live2air IFE installed during the Virgin Blue days, i.e as seen in this picture: http://www.airliners.net/photo/Virgi...e-Airlines/Boeing-737-7Q8/2106499/

1.2% performance degradation (whatever that means) on top of an extra 15kg fuel for a short sector, according to this post:
http://www.pprune.org/dg-p-general-a...294372-whats-bump-vbulletin-c.html

Quoting YVRFlyer (Reply 11): Out of curiosity, what kind of drag/fuel penalty does the bump and extra weight typically put on an aircraft? I can't find any info on that.

Or better yet, why is a "hump" even necessary? Is the equipment that large that it won't fit without altering the exterior?

Quoting YVRFlyer (Reply 11): Out of curiosity, what kind of drag/fuel penalty does the bump and extra weight typically put on an aircraft? I can't find any info on that.

Quoting a300 american (Reply 12): great question, I'd like to know as well..............

Agreed; great question. I'd also like to know if the location of the dome on the fuselage makes a difference. On the 77W it's obviously forward, and on the 737s it's toward the aft portion

It is a satellite dish basically. B6 has them on their aircraft and that is what receives the DirecTV satellite signal for the TV's onboard. With the new ViaSat WiFi option coming onboard soon, all existing dishes will need to be replaced with ones that are capable of receiving the ViaSat signal. These new dishes will be a bit bigger and require a bigger housing than the ones currently affixed to the a/c.

Quoting airbazar (Reply 14): Or better yet, why is a "hump" even necessary? Is the equipment that large that it won't fit without altering the exterior?

The dish mounts on the exterior of the fuselage. It sits on a platform that conforms to the surface and give a nice large flat mounting surface. The dish itself is a large flat platter about 2 ft across that rotates to aline with the overhead satellite. To get a signal it has to be exterior of the skin. The radome is to protect the dish and provide aerodynamics. Weight is really much. The radome is really nothing and even the dish assembly can be moved by one person.

Here is TC-JJE the first new build 77W for Turkish Airlines with the same WiFi dome.

http://www.airliners.net/photo/Untit...ines)/Boeing-777-3F2-ER/1792131/L/

anyone know what the cost will be for inflight internet on 8 hour flight?

Cathay Pacific obviously have another brand of WiFi dome. There's is located aft as is seen on B-KQB. It looks better near the back as seen on this Cathay 77W. With the WiFi dome up front. It breaks up the clean lines of the 77W.

http://www.airliners.net/photo/Untit...cific/Boeing-777-367-ER/2108040/L/

Quoting airbazar (Reply 14): Or better yet, why is a "hump" even necessary? Is the equipment that large that it won't fit without altering the exterior?

It'll fit inside but it can't see through the skin. To put it inside you'd have to splice a non-conductive piece of structural skin into the existing skin. That is, to put it mildly, a challenging structural issue and you'd probably gain as much weight on the splice as you saved on drag.

Tom.

I have seen similar but smaller humps on QR's A330's at MAN. They are quite noticeable when park alongside other A330's such as TCX or EY.

Saudi Arabian has a WiFi dome similar to placement like Cathay Pacific. Saudi Arabian's is just behind the L4 door as seen here on HZ-AK11

http://www.airliners.net/photo/Saudi...lines/Boeing-777-368-ER/2183529/L/

TAM's WiFi dome is low profile too as is seen here on PT-MUE.

http://www.airliners.net/photo/TAM/Boeing-777-32W-ER/2168334/L/

These 'humps' are not dishes, but an array of electrically steered antennas on a machined mount, with an aerodynamic cover, used for satellite communications. These are on the top of the fuselage, in order to provide coverage right up to polar regions, where the geostationary Inmarsat transponders are 25,000 miles above the equator.

Inmarsat use four satellites to cover Pacific, Indian and Atlantic (2) to provide seamless oceanic coverage for satellite communications with phones, data and airline service communications, such as ACARS. Clearly wi-fi comes into the mix, according to specific airline set-up needs. Most wide-body aircraft use top-mounted antenna assemblies, but lower 'conformal' antennas have been fitted, with a pair on each side of the fuselage provide coverage with less drag, but reduced coverage nearer the polar regions. The satellite system requires a beam-steering unit, as a part of the 'above ceiling' mounted equipment, linked to the flight management system, to electronically steer and direct direct the antenna elements to the specific Inmarsat transponder location.

Quoting DuncanTruro (Reply 25): Most wide-body aircraft use top-mounted antenna assemblies, but lower 'conformal' antennas have been fitted, with a pair on each side of the fuselage provide coverage with less drag, but reduced coverage nearer the polar regions. The satellite system requires a beam-steering unit, as a part of the 'above ceiling' mounted equipment, linked to the flight management system, to electronically steer and direct direct the antenna elements to the specific Inmarsat transponder location.

I'm having trouble visualizing why side-mounted dishes would be less able to pick up the comsats in the polar regions.

If the birds are in geosynchronous orbit, then they hover above the equator at very high altitude. If you are flying over a pole, the satellite is basically off the side of the aircraft, not above it. If anything, I'd expect a side-mounted antenna to perform worse at equatorial latitudes.

What am I missing?

Quoting VHHYI (Reply 13): 1.2% performance degradation (whatever that means) on top of an extra 15kg fuel for a short sector, according to this post: http://www.pprune.org/dg-p-general-a...294372-whats-bump-vbulletin-c.html

Thank you for that, VHHYI!    Doing a back-in-the-head calculation (I'm probably off the mark), on an ULH flight the lost opportunity (i.e. extra weight of the equipment, extra fuel to carry fuel), etc must be around 1 tonne of cargo or 7-10 passengers + luggage. It would be interesting to see what kind of pricing model ULH airlines pursue.

Quoting VHHYI (Reply 13): 1.2% performance degradation (whatever that means) on top of an extra 15kg fuel for a short sector, according to this post: http://www.pprune.org/dg-p-general-a....html

My friends at WN said that the dish almost negates the benefit of winglets on their 737's

Quoting sevenheavy (Reply 2): Its probably for Wifi comms equipment.

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Photo © Bill Shemley

It is a Low-profile Ku-Band satellite communications antenna.

This allows broadband speed data communications with the ground (and hence, the internet).

The WiFi equipment (if installed) is inside, behind the cabin panelling.

Quoting BA (Reply 7): Panasonic eXConnect

Panasonic eXconnect does not have to use that antenna (the low profile Ku-band), it can use the SwiftBroadband high-gain L-band antennae too... and, one is also installed on that 777... at the back (and that's a standard linefit option, whereas the Ku-band antenna, is not (or not yet)).

The L-band antennna is found in a lot of widebody aircraft, but just because they have it does not mean they can have internet for the pax.

Quoting YVRFlyer (Reply 11): Out of curiosity, what kind of drag/fuel penalty does the bump and extra weight typically put on an aircraft? I can't find any info on that.

1.2% degradation means you add 1.2% for your fuel burn... that's for the older Ku-band antennas. I think the latest ones are about 0.8% for 737s, and about 0.6 or less for 777s... I forgot the numbers quoted by the antenna manufacturers. The L-band antenna's fuel penalty is about 1/4 to 1/2 of those numbers. (Those are additional fuel burn per given trip on the new gross weight which has the additional weight of the antenna systems).

Quoting airbazar (Reply 14): Or better yet, why is a "hump" even necessary? Is the equipment that large that it won't fit without altering the exterior?

The hump, is necessary for Ku-band (and the latter Ka-band that's coming up in a few years).

Quoting andytb77 (Reply 15): Agreed; great question. I'd also like to know if the location of the dome on the fuselage makes a difference. On the 77W it's obviously forward, and on the 737s it's toward the aft portion

The position of the antenna also depends on aerodynamics (how it adds drag to the aircraft), how it affects the airflow to the vertical stabilizer (and rudder), effects of icing to all those, etc etc etc... The preferred position on Boeing aircraft (widebody and narrowbody) is, the back. That place however is, in this aircraft, taken up by the L-band antenna. So, the next preferrable position, is in front, where it sits in the picture.

For Airbus aircraft (both narrowbody and widebody), the preferred position is in front. Airbus is rather fanatical about clean airflow on the rear portions of the aircraft (at one stage one antenna manufacturer mentioned the high speed flutter characteristics of an A330 with an satcom antenna on the back, is 'undesirable')...

Quoting spchamp1 (Reply 16): B6 has them on their aircraft and that is what receives the DirecTV satellite signal for the TV's onboard. With the new ViaSat WiFi option coming onboard soon, all existing dishes will need to be replaced with ones that are capable of receiving the ViaSat signal. These new dishes will be a bit bigger and require a bigger housing than the ones currently affixed to the a/c.

Yes, B6 had the one-way (receive only) antenna, now they gotta change to the new 2-way... bigger housing, but more streamlined than the 'old' ones.


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Photo © Bill Shemley

Ah, a side-shot! You can see the Ku-band antenna on the front hump, and the L-band antenna on the rear hump (just behind door R4, on top).

Quoting pdxswa (Reply 20): Cathay Pacific obviously have another brand of WiFi dome.

Quoting pdxswa (Reply 23): Saudi Arabian has a WiFi dome similar to placement like Cathay Pacific.

Quoting pdxswa (Reply 24): TAM's WiFi dome is low profile too as is seen here on PT-MUE.

For CX, it's the standard L-band linefit (Cobham's HGA-7000, 7001, or Thrane&Thrane's equivalent) antenna. And no, having it does NOT mean the aircraft is wi-fi equipped...

Eg: Have a look at this photo taken from the pre-internet-onboard days... you can see the satcom antenna (L-band) at the same/similar postion.



These antennas are often used for simple cockpit satphone and ACARS through satcom.

And, some, have installed 2 of those antennas and yet, no internet back then... here's an example:

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Photo © Alexander Schwarz


Those humps are simply... Antennas... you can have mechanical steering or electronic beam steering antennas for L-band, the Ku-band systems however, need mechanical steering.

Quoting DuncanTruro (Reply 25): These 'humps' are not dishes, but an array of electrically steered antennas on a machined mount, with an aerodynamic cover, used for satellite communications.

Yes, but the big humps in front on the Turkish and AA jets are Ku-band antennas, not using Inmarsat's Swift or Swiftbroadband.

Quoting DuncanTruro (Reply 25): Inmarsat use four satellites to cover Pacific, Indian and Atlantic (2)

For Inmarsat-3 network (for airplanes means, AeroClassic, AeroH+, Swift64), does use 4 satellites. Inmarsat-3 is used mainly for safety services only when it comes to data transmissions, mainly ACARS, the airtime is too cost prohibitive for passenger internet use, and even the satcom calls are expensive! The newer Inmarsat-4 (SwiftBroadband, and now the older aero services of Inmarsat are being moved to the Inmarsat-4) network uses 3 satellite.

The SwiftBroadband can have the BSU and amplifiers etc, in a single box below the ceiling now, and doesn't have to be linked to the aircraft system (although it does need position and orientation data feeds through an ARINC429 interface, or you buy a dedicated referencing unit (GPS and orientation) independent of the aircraft's navigation system).

For the benefit of those interested... This is one of the better Ku-band systems around (same make as those used by Row44 for WN and DY):


Why is the hump needed? well, the antenna head needs to be on top of the aircraft's fuselage... without a cover, it would look like:

Now, the 'hump' is the cover to make it more aerodynamic.

Those L-band antennas can come in various shapes and sizes, but the ones found on the widebodies are typically like this:


Mandala499