PDA

View Full Version : VLS in landing configuration


Pilotas
30th Nov 2016, 14:43
good day
a little bit confused about VLS on airbus. here is the definition of VSL in OM
VLS : Lowest Selectable Speed.
Represented by the top of an amber strip along the airspeed scale on the PFD.
Computed by the FAC, based on aerodynamic data, and corresponds to 1.13 VS during
takeoff, or after a touch and go.
Becomes 1.23 VS, after retraction of one step of flaps.
Becomes 1.28 VS, when in clean configuration.
Note: If in CONF 0 VLS were 1.23 VS (instead of 1.28 VS), the alpha protection strip
would hit the VLS strip on the PFD.
Above 20 000 ft, VLS is corrected for Mach effect to maintain a buffet margin of 0.2 g.
In addition, VLS increases with speed brakes extension.

but there is nothing written about VSL in landing configuration with config 3 or full. so my question is what is the factor of Vs the VSL representing in landing conficuration?

FlyingStone
30th Nov 2016, 23:03
In the same chapter (PRO-SUP-10), take a look at the Vs - stall speed:

Authorities allow aircraft of the A320 family to use the following factors:
‐ V2 = 1.2 0.94 VS1g = 1.13 VS1g
‐ VREF = 1.3 0.94 VS1g = 1.23 VS1g

So, VREF is 1.23 VS1g and VREF is VLS in CONF FULL, so VLS is 1.23 VS1g in any configuration with flaps extended except during takeoff.

Don't blame yourself, it's the way Airbus manuals are written.

Pilotas
1st Dec 2016, 11:11
yes I have read this but what makes you think that Vls in landing config = Vref? could you point where it is provided? thanks

upd. I found it by myself. thanks anyway
http://s9.uploads.ru/d/eFMyE.jpg

Lantirn
1st Dec 2016, 21:41
PRO/SUP/10/OTHER_SPEEDS also