PPRuNe Forums - View Single Post - VMCG less than VMCA
View Single Post
Old 19th December 2009 | 09:06
  #31 (permalink)  
rudderrudderrat
 
Joined: Oct 2009
Posts: 1,270
Likes: 0
From: UK
Hi JT, you are correct.

Although there is no clue about that in FCOM “Use rudder to prevent yaw. Shortly after lift-off, ß target will appear. Adjust rudder position to zero the ß target. Control heading conventionally with bank, keeping the ß target at zero with rudder.”

But from the FCTM “When the beta target is centred, total drag is minimized even though there is a small amount of sideslip. The calculation of the beta target is a compromise between drag produced by deflection of control surfaces and airframe drag produced by a slight sideslip. Centering the beta target produces less total drag than centering a conventional ball, as rudder deflection, aileron deflection, spoiler deployment and aircraft body angle are all taken into account. The crew will keep in mind that the yaw damper reacts to a detected side slip. This means that, with hands off the stick and no rudder input, the aircraft will bank at about 5 ° maximum and then, will remain stabilized."

But I'm still puzzled by what Airbus actually refers to as "VMCA". Their A319 V2 "VMCA" CONF3 is 119 kts - but their "VMCA" VMCL CONF3 on the GA is 108 kts. I think the 108kts is what I would understand to need full rudder and 5 degs bank to hold heading. I think their V2 VMCA is controllable with wings level so I can transition from ground to flight.

Thanks Haroon for a great thread.
rudderrudderrat is offline  
Reply