Boeing 787: different HF-antennas

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conaly
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Posts: 841
Joined: Mon May 30, 2005 10:50 pm

Boeing 787: different HF-antennas

Mon Feb 11, 2019 3:05 am

While I'm sitting here at HND airport and having a lookout to the tarmac, I've noticed, that on the 787-9 the HF-antenna was missing on the spot, where it is located on the B787-8. After a quick search on google, I found this graphic: https://i.stack.imgur.com/me4UV.jpg

So it seems it was relocated from the leading edge in the middle to the area above the root. Does anyone know the reason for this change? Why did the not use one common design here? And if the -9-design is better, why not use it on newly delivered 787-8?

Some pictures
B787-8:


B787-9:
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wildwobby
Posts: 26
Joined: Sun Feb 12, 2006 7:27 am

Re: Boeing 787: different HF-antennas

Mon Feb 11, 2019 3:50 am

I believe the 787-9, unlike the 787-8, has an HLFC system on the leading edge of the v-stab.
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Faro
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Re: Boeing 787: different HF-antennas

Mon Feb 11, 2019 7:45 am

IIRC, the 789 implemented a (limited) laminar flow technology on the vertical stabilizer...if this is the case, the new HF antenna location lower down on the leading edge may be to help with that implementation...to furnish a smooth, seamless leading edge surface to enhance the laminar flow further back on the face of the fin...


Faro
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akoma
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Re: Boeing 787: different HF-antennas

Thu Feb 14, 2019 1:37 pm

Faro wrote:
IIRC, the 789 implemented a (limited) laminar flow technology on the vertical stabilizer...if this is the case, the new HF antenna location lower down on the leading edge may be to help with that implementation...to furnish a smooth, seamless leading edge surface to enhance the laminar flow further back on the face of the fin...


Faro


In the 789s we have, the HF antenna is a grounded 5 foot aluminium tube located just below the dorsal panels (the bottom part of the leading edge of the vertical stab). The leading edges are not used as an antenna.
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Faro
Posts: 2088
Joined: Sun Aug 12, 2007 1:08 am

Re: Boeing 787: different HF-antennas

Sat Feb 16, 2019 9:45 am

akoma wrote:
Faro wrote:
IIRC, the 789 implemented a (limited) laminar flow technology on the vertical stabilizer...if this is the case, the new HF antenna location lower down on the leading edge may be to help with that implementation...to furnish a smooth, seamless leading edge surface to enhance the laminar flow further back on the face of the fin...


Faro


In the 789s we have, the HF antenna is a grounded 5 foot aluminium tube located just below the dorsal panels (the bottom part of the leading edge of the vertical stab). The leading edges are not used as an antenna.



Thanx...funny that they are made of aluminium...I would have thought that some manner of copper alloy would give better performance given the higher conductivity...


Faro
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