Fins on 737 Empennage?

[Vibes]

Hi Guys,

With regards to the following link, I would like to ask if anyone do happen to know as to the purpose of the 4 fins that are located between the vertical and horizontal stabilizers on the 737.Are these 4 fins some form of aerodynamic device? I sincerely do hope that you guys could shed some light as to its purpose.

Photos: Boeing 737-7L9 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Gol-Linhas-Aereas/Boeing-737-7L9/1936626/L/&sid=c45fc67fe7f7b3293a0b4fd9c9644359)

Regards,
Vibes

[kenparry]

They are vortex generators. See Vortex generator - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Vortex_generator)
Not a particularly good explanation, but it covers the basics.

[sudden Winds]

Check Chris Brady's website The Boeing 737 Technical Site (http://www.b737.org.uk/) he will definitely have an answer.

[Moi/]

Cleans the airflow up over the base of the fin, allows the rudder smooth operation.

[JammedStab]

A look at airliners.net showed that they do not appear to be on the 100 series. I wonder why. I also wonder if they are a retroactive mod or came out for some reason at the beginning of 200 series manufacturing.

Anybody?

[Brian Abraham]

From Fuselage - ATA53 (http://www.b737.org.uk/fuselage.htm#AFT_BODY_VORTEX_GENERATORS)

AFT BODY VORTEX GENERATORS

There are four vortex generators on each side of the rear fuselage above the horizontal stabiliser. The 737-1/200s also had three vortex generators below each stabiliser. They were probably installed to energise the airflow at the stagnation point at the tailcone, thereby reducing drag and giving a slight performance advantage.

Classics were initially produced without any aft body vortex generators (see photo. However the upper vortex generators were reinstated after line number 2277 (May 1992 onwards). This was to reduce elevator and elevator tab vibration during flight to increase their hinge bearing service life.

The CDL says that if any of these vortex generators are not fitted or missing “occasional vertical motions may be felt which appear to be light turbulence These motions are characteristic of this airplane and should not be construed to be associated with Mach buffet.”

[Vibes]

Hi guys,

Thank you very much for the prompt response.Really appreciate it!