LockOn: Flaming Cliffs

The Su-25T Physics Model

The following new features have been introduced with the Su-25T:

• Plane dynamics are always calculated on the basis of the same physics equations describing transnational and rotational motion of a solid body under the influence of external forces and moments disregarding the nature of their origin.
• The center-of-gravity can change its location within the speed axis system.
• When calculating aerodynamics characteristics, the plane is represented as a combination of airframe components (fuselage, outer wing panel, stabilizer, etc). Separate calculations of aerodynamics characteristics are performed for each of the above named components in the entire range of local angles of attack and sliding (including supercritical), local dynamic pressure and Mach number taking into consideration deviation and grade of destruction of control instruments and some airframe components.
• The engine is represented as a complicated system of the main components models: compressor, combustion chamber, turbine and starter-generator.

When flying the Su-25T, the new physics model shines in the following ways:

• Transition between flight modes is performed in a smooth manner, without abrupt changes of angle rotational speeds and attitude (for example, after tail-dive or when landing with angle of roll, on one of the landing-gear).
• Gyroscopic effect of the plane's rotation is taken into account.
• Asymmetric effect of external forces is considered as well as the effect of external forces not going through the center-of-gravity (for example, engine thrust and drag chute force). These forces are correctly calculated at any flight stage.
• Recoil force when firing the cannon is taken into account.
• A notion of lateral and longitudinal center of mass is introduced. This notion can change depending on fuel load and external loadout.
• Asymmetrical pylon loading now influences the characteristics of lateral control (depending on flight speed and regular overload, etc) is also considered.
• Aerodynamics are accurately modeled in the whole range of angles of attack and glide. This is especially noticeable when performing a tail-slide and aileron roll.
• Efficiency of lateral control and degree of lateral and static lateral stability depend on angle of attack, longitudinal and lateral center-of-gravity.
• Wing autorotation mode when performing a rolling rotation at great angles of attack is taken into consideration.
• Kinematics, aerodynamic and inertial interaction of longitudinal, dihedral and lateral channels (yaw movement when performing a rolling turn, rolling motion at rudder pedal forward, etc).
• Angle of glide availability is determined by the pilot's efforts and the plane's position.
• In case of the airframe damage, the plane's motion is performed in a natural way by means of deletion of the damaged component from aerodynamics calculations fully or partially.
• The model guarantees realistic stall characteristics of stall (rocking wings with simultaneous course oscillation).
• Diverse effects of aerodynamic shaking depending on flight mode: exceeding the allowable angle of attack, Mach number, etc.
• Engine thrust at idle corresponds to the real one.
• Idle RPM depends on the speed mode: altitude and Mach number, weather conditions: pressure and temperature.
• Short RPM over speeding is modeled at acceleration time.
• Acceleration time, engine throttling and its controllability depends on rotation speed.
• Gas temperature behind the turbine is dependent on engine operating mode, flight mode and weather condition.
• Specific fuel consumption is non-linearly dependent on engine operating mode and flight mode.
• Dynamics of engine operating parameters (gas speed and temperature) is accurately modeled in regards to engine start and shut down. The mode of engine autorotation from ram airflow, engine freeze-up (accompanied by continued temperature rise) when throttle position is in the wrong position at engine start up. Flight restart and windmill air restart.
• Each hydraulic system supplies its own group of hydraulic pressure systems (landing gear, aileron actuator, flaps, wing leading edge flaps, adjustable stabilizer, nose-wheel steering, brake system, etc).
• Pressure in the left and right hydraulic systems depends on the balance of hydraulic pump efficiency and operating fluid consumption by hydraulic pressure users (boosters, actuators, etc). Hydraulic pumps' efficiency depends on the right and left engines speed respectively; operating fluid consumption depends on their state.
• Both catastrophic and partial hydraulic actuators failure at pressure loss in a corresponding hydraulic system is modeled.
• Pitch trimming, yaw model and aileron trimming mechanism models are included, each using a different logic. In particular, pitch trimming position does not influence rate controller position at near-zero flight speed. Trimming tab serviceability depends on electric power availability in aircraft electrical system.
• Extension and retraction speed of high-lift wing devices and adjustable stabilizer depends on fuselage pressure.
• Extension of wing high-lift devices for a more maneuvering configuration at a greater indicated airspeed leads first to partial and then to complete hydraulic actuator blocking. This causes fuselage pipe damage, hydraulic liquid leakage, and fuselage pressure drop.
• Landing gear extension at a high indicated airspeed first leads to partial and then to complete hydraulic actuator blocking, causes fuselage pipes damage, hydraulic liquid leakage and fuselage pressure drop.

Su-25T 3D Model

• Number of polygons: 52,000.
• Number of parts (sub shapes): 547.
• Skin: consists of 3 textures 2048x1024, one texture 1024x1024 , 3 textures 1024x512 , one texture 512x512. Total volume of texture is: 26 MB.

Construction