A320 series CFM56 engine's strake

[bio161]

Hi all,
a question concerning the engine's strake on the A320 series of the CFM manufacture. :8

Could anybody, for sure more expert than me, tell me what is the precise need of them and why on the A320 the strake is present ONLY on the inner side of the engine and not on both sides as on the A319? :confused:

Thanx to you all,
always happy landings! :ok:

Examples:

A320 with strake only on the inner side of the engine:

Photos: Airbus A320-211 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Air-Canada/Airbus-A320-211/1864437/L/&sid=3a208db9270f36a3f970955dda2db85e)

A319 with the strakes on both sides of the engine:

Photos: Airbus A319-111 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Iberia/Airbus-A319-111/1864657/L/&sid=7ea00e2b2d007657ed5a15cbcb47e924)

[Turbine D]

bio161

The strake reduces the flaps down stall speed. Besides the Airbus A-320, only one strake (inside) is used on the heritage Boeing 737's. The reason has to do with the wing leading edges, having slats deployed and the relative position of the nacelle in relationship to the wing. The strake acts like a vortex generator.

[Dan Winterland]

The 321 has two as well. If you operate with one missing (Possible if a 320 cowling is borrowed for a 320), from the CDL you have to add 5 knots to VApp.

[bio161]

Hi there,
thank you for your answers guys!

But i don't get one thing. If the strakes are there to reduce the flpa down stall speed then why is there this difference between A319-320-321?

Because it looks to me that the construction of the wing and of the engine is the same for all the types. So the air stream, i suppose, it should be the same around the engine's nacelle and the wing. Or? So again why the need of 2 different strakes? :confused:

[XPMorten]

The A321 has a different flap and camber then the A320/319/18.