El Su-27, designación OTAN Flanker, es uno de los pilares de la aviación de combate rusa actual. Construido para contrarrestar al F-15 Eagle estadounidense, el Flanker es un caza de superioridad aérea bimotor, supersónico y de gran maniobrabilidad. El Flanker es capaz de atacar objetivos más allá del alcance visual y en un combate aéreo cerrado, dada su asombrosa capacidad a baja velocidad y su maniobrabilidad en ángulos de ataque elevados. Gracias a su radar y a su sigiloso sensor de búsqueda y seguimiento por infrarrojos, el Flanker puede emplear una amplia gama de misiles guiados por radar e infrarrojos. El Flanker también incluye una mira montada en el casco que le permite simplemente mirar a un objetivo para fijarlo. Además de sus potentes capacidades aire-aire, el Flanker también puede armarse con bombas y cohetes no guiados para cumplir una función secundaria de ataque a tierra.
El módulo Su-27 para DCS World se centra en la facilidad de uso sin complicadas interacciones en la cabina, reduciendo significativamente la curva de aprendizaje. Así, el Su-27 para DCS World puede controlarse mediante comandos de teclado y joystick con un enfoque en los sistemas más críticos de la cabina.
Directional yaw control is performed by symmetrical deflection of the rudders. Transmission of inputs from pedals to the rudders is conducted by means of a mechanical linkage. Additionally, yaw sub-channel servo units of the fly-by-wire system are mechanically connected to the rudders with half-travel authority.
Directional channel rudder control schematic block diagram
The yaw sub-channel of the fly-by-wire system includes the following automatic devices:
Roll-Yaw crossfeed system operates in accordance with side stick inputs. It deflects the rudders to the same side as the control stick. This eliminates adverse sideslip caused by the difference in drag by half-wings. It also improves a lateral controllability, especially at high angles of attack.
Rudder – AoA diagram
Due to this, lateral control is preserved up to an angle of attack of 28 degrees and there is no roll reversal due to control stick movement.
Roll rate – AoA diagram
Yaw stability system operates in accordance with lateral acceleration inputs and it provides required characteristics for aircraft yaw stability due to the aircraft having relaxed statistic yaw stability. This is due to the peculiar properties of the Su-27’s aerodynamic configuration aft of the center of gravity, elongated lateral wing area of the fuselage, and forward fin displacement. The operating principle of the Su-27’s yaw stability system is similar to that of the pitch stability augmentation system.
Yaw damper provides the required characteristics needed for lateral dynamic stability.
In order to decrease loads on the fins and the aft fuselage as a whole at the speeds of over 600 km/h, and when the landing gear is up, a spring mechanism is connected to the directional control system providing for the locking stop in the mid-travel of the pedals to each side. It is forbidden to override the locking stop of the pedals at the airspeeds over 600 km/h. This is why pedal travel at these speeds is reduced by half in this simulation.
The powerplant of the Su-27 includes two АЛ-31Ф (AL-31F) engines, each of which has its own turbine starter ГТДЭ-117 (GTDE-117). Because both engine have a separate starter, both individual and simultaneous starting of both engines is possible.
In order to start the engines on the ground, one should:
After this, the engine starter doors will open, the door limit switch actuates and puts the starter circuit into operation. Based on the starter circuit command, fuel is provided to the turbine starter and the annunciator "ЗАПУСК" (START) is lit in the cockpit.
The starter circuit turns on the electrical starter motor, ignites the turbine starter, and supplies oxygen to the turbine starter. After ten seconds, the turbine starter will turn off these accessories and simultaneously turns on ignition of the main chamber. The turbine starter spins up the engine rotor and the fuel control unit controls fuel flow to the main chamber. After ignition in the main chamber, the turbine comes into operation and accelerates the engine rotor together with the turbine starter. At 35% of the engine RPM, the ignition exciter in the main chamber switches off. At 53% of the engine RPM, or after 50 seconds, the turbine starter and starter circuit are switched off, which is indicated by the annunciator "ЗАПУСК" (START) turning off. The engine then reaches IDLE mode automatically.
The nozzle control system is intended to change the diameter of the exhaust nozzle in accordance with the desired law.
Before engine start, during the ignition and when in IDLE mode, the nozzles are completely open to provide the most favorable conditions for engine start: the greatest torque of the turbine, minimum overheating, and the minimum thrust during IDLE mode. When the throttle is moved forward to 77-81% of the engine RPM, the nozzles close partially in order to produce improved thrust characteristics. When the afterburner is switched on, the nozzles opens in order to maintain the turbine exhaust temperature. As the thrust augmentation ratio increases, the nozzles open.
When the landing gear is extended, the nozzles partially closed in order to preserve the power margin and to avoid nozzle contact with the runway during the touchdown. Due to this, the thrust is increased when on the glide path. In order to decelerate, the speedbrake should be used.
