Re: teeny vertical fins

Date:         13 Feb 97 01:37:41 
From:         ehahn@mitre.org (Edward Hahn)
Organization: The MITRE Corporation
References:   1
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In article <airliners.1997.384@ohare.Chicago.COM>, miloro@cric.com (Scott
Miloro) wrote:
>I have noticed that a number of Boeing products have small (looks like 2 feet
>or so) vertical fins on the dorsal portion of the Fuselage.  I know for sure
>I saw these on a VA B747-200 at BOS.  Methinks they are on 757 type aircraft
>as well.  So the question is...what are these things, and what are they doing?

You could be seeing VHF blade antennas.  These are small (about a foot or so
in length) and hang from the VENTRAL side  (underside) of the fuselage.

Their purpose, as should be obvious by the name,  is to send and receive VHF
radio signals (comm & nav).

As for a "dorsal" fin, B737s have it - it is the extension of the leading edge
of the vertical stabilizer forward along the fuselage.  I am not aware of any
aircraft with a separate, unconnected dorsal fin (other than certain aircraft
modified for electronic monitoring by foreign governments).

ed

>>>>  Ed Hahn    |    ehahn@mitre.org    |    (703) 883-5988  <<<<
The above statement is the opinion of the author.  No endorsement
or warranty by the MITRE Corporation is expressed or implied.
Really, I wouldn't kid you about a thing like this.