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Japan can't outgun China's J-20 with F-35A purchase(2)

2015-05-28 15:07   Editor:admin   
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Core Tip: In terms of transonic flow, the lift coefficient of the F-35 is 1.7 at an angle of 35 degrees and a speed of Mach 1.1, the lift-drag ratio at an angle of attack of 5 degrees and a speed of Mach 0.9 ca

In terms of transonic flow, the lift coefficient of the F-35 is 1.7 at an angle of 35 degrees and a speed of Mach 1.1, the lift-drag ratio at an angle of attack of 5 degrees and a speed of Mach 0.9 can reach a maximum of 8. Third generation aircraft are designed with transonic maneuverability as a priority, but this is clearly not the F-35's strong point, even though its maximum lift coefficient approaches the 1.8 of France's Dassault Rafale. Its lift-drag ratio is poorer, however, as its lift coefficient improves, this explains why the cross-sectional area of the body of the plane is quite large, although the back sweep angle of the wings is smaller, which improves subsonic flight, it also leads to heightened resistance in transonic flight. The maximum angle of attack of the F-35 at transonic speeds is still quite large, however, at a maximum of 35 degrees.

In terms of supersonic flow, the lift coefficient of the F-35 reaches 1.8 at an angle of attack of 35 degrees and a speed of Mach 1.3; while at a 5 degree angle of attack at Mach speed the lift-drag ratio reaches 4, a big gap from the F-22's supersonic lift-drag ratio of 5. As the bypass ratio of the Pratt & Whitney F135 afterburning turbofan engine is quite large, its propulsion force at high speeds and high altitudes is lesser, making the F-35 comparable to supersonic third generation fighters, although it can't match the capabilities of third generation fighters with a canard configuration, and is closer to the capabilities of the General Dynamics F-16 Fighting Falcon. Overall, the F-35 was designed with subsonic maneuverability and long-range subsonic flight in mind, which explains why it is mainly flown in cruise and aimed at launching ground strikes. The F-35 is notable for its maneuverability at all speeds and angles of attack and its stability in making turns at subsonic speeds, making it more agile than third-generation fighters, although it does not perform well at transonic speeds. In sum, the F-35 sees a clear improvement from the F-16 in angle of attack and turning speed, with a slight upgrade in the stability of turns, although its transonic flight capabilities are slightly worse than the stealth version of the F-16. This suggests that it is most suited to be a ground attack aircraft, although it could also be termed a multirole aircraft. 

The F-35's Stealth Capabilities

The plane features the following mechanisms aimed at electromagnetic scattering, listed in order of intensity: corner reflectors, concave resonators, polished surface reflection and knife-edge diffraction, surface backscatter, creeping wave diffraction, second-order and multiple scattering, as well as discontinuous surface scattering. The corner reflectors between the fuselage and the wings, the vertical tailfins and the horizontal stabilizers and between the external pylons, as well as the concave shape of the nose-mounted Electro-Optical Targeting System, the cockpit and the air inlets also prove very effective in reducing the craft's radar cross-section (RCS), at around 10-0 decibels, which corresponds to over 10 square meters to under 10 square meters in (RCS). The diffraction and scattering caused by sharp edges and lines on the plane have less of a contribution, at around 0 or -30 decibels, which corresponds to an RCS of one thousandth of a square meter.

The F-35 is equipped with an AN/APG-81 Active electronically scanned array-radar. The radar array face upwards at a slight angle, which reflects incoming radar waves that enter the radar housing away from the receiver. The serpentine air inlets and DSI covers the entire front of the engine and the cockpit is plated with metal to reflect incoming radar, preventing it from entering the cockpit, resulting in scattering; The internal weapons bay prevents reflection between external equipment held on pylons; the leading edges of the wing, the horizontal tail stabilizers and the vertical tailfins are all parallel, as are the trailing edges of the main wing, the horizontal tail stabilizers and the vertical tailfins, which aids in scattering; the surface of the body of the plane employs a sawtooth design, sending creeping wave away from the receiver. Currently the F-22's head-on RCS is between -20 and -30 decibels, or one hundredth to one thousandth of a square meter. Due to the sensors embedded in the body of the F-35, it has limited ability to scatter creeping waves. Taking all of this into account, the face-on RCS of the F-35 is likely between -10 and -20 decibels, or between one tenth and one hundredth of a square meter. This means that the F-35 can cut down the distance at which it can be detected by radar from 100 km to 20-40 km.

The F-35's Radar and Electromagnetic Interference Abilities

As mentioned above, the F-35 is equipped with an AN/APG-81 Active electronically scanned array-radar, which has strong detection capabilities as well as a multi-function integrated radio frequency system (MIRFS), which can carry out electromagnetic interference, facilitate communications and identify targets. The F-22 is equipped with the AN/APG-77 low probability of intercept radar, composed of 2,200 transmit/receive modules, each with power of around 10 Watts, giving it peak power of 22 kiloWatts. When operating with a duty cycle of 25%, it operates at around 5 kW. Due to the small size of the nose of the craft, the APG-81 radar has less components than the APG-77, although there is currently no concrete figure, it is likely around 1,200, giving it peak power of 12 kW and average power of around 2 kW.

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