User manual
Aerosoft F-16 Fighting Falcon 1.00 Manual
Page 12 of 46
RELAXED STATIC STABILITY
As opposed to many other aircraft the F-16 is built for an unstable mode, so called Relaxed Static
Stability (RSS). RSS means that aerodynamically the F-16’s point of lift is forward of the aircraft’s Center
of Gravity (CG). This means that with increased AOA the lift will increase and thereby the AOA will
increase and increase lift further. In the end the aircraft will break or stall. The aircraft will, as a result,
not find its stable position in flight. To control this, the FLCS is dependent continuous feedback from the
gyros and accelometers. With increased airspeed the point of lift will move aft and at a speed of Mach
1.0 the lift will be at the same point as the CG. Above Mach 1.0 the lift will be behind the CG. This means
that the F-16 is aerodynamically stable above Mach 1.0. Advantages with an unstable aircraft:
Reduced Drag
Increased maneuverability
Rapid response from pilot inputs
Smaller control surfaces which means less weight.
SPEEDBRAKES
The speed brake is controlled by the SPD BRK switch on the throttle grip. The switch has 3 positions:
Aft position is spring-loaded to mid position. With the switch in aft pos. the speed brake is
opened gradually.
Mid position. Speed brake will remain in last position used.
Fwd position. Speed brake closes to fully closed position.
The speed brake can deflect to 60° in the fully open position. With Landing Gear Handle Down and Main
Landing Gear Down and Locked the operation of speed brakes will be limited to 43° deflection to
prevent it from scraping the ground during landing. This limit can be overridden by holding the SPB BRK
switch in the aft position. If the switch is released the speed brake will go back to 43° open. When the
aircraft has Nose Landing Gear Weight On Wheel, the speed brake can be fully opened to 60° and again
function as a brake. The purpose of speed brakes is as follows:
Aerodynamic braking of the aircraft
Increase of maneuverability
Easier to control landing speed.
LEADING EDGE FLAPS
While most people are familiar with trailing edge flaps (the control surfaces at the rear of the wing that
deploy to increase lift at the expense of additional drag, the F-16 also has Leading Edge Flaps. They
increase lift during take-off and landing and automatically change the curvature of the wing in various
flying conditions. This gives better take off/landing performance, lift-to-drag ratio resulting in better
maneuverability and a more efficient vertical tail during high AoA. The LEF is mechanically driven by a
Power Drive Unit dependent on steering input from Electronic Component Assembly (ECA). The input
signals to the ECA are calculated from Mach-number, AoA and Altitude, during flight. The LEF can deflect
from 2° to 25° dependent on what the ECA tells it to do. On landing the LEF will automatically go to 2°
UP position when the aircraft has Weight On Wheels and the speed on wheels is 60 kts. The LEF is
controlled by the LE Flaps switch. This has two positions; AUTO or LOCK. It remains in AUTO during
normal flight. If put in LOCK it will remain in the position it is set, independent on what the ECA says.