LCA TEJAS and what makes it stand out

[porky_kicker]

Some of the advanced fight modes being implemented or has been implemented to LCA digital quad redundant FBW flight control system

1. auto low-speed recovery (ALSR)

In auto low-speed recovery (ALSR) mode, the flight control system (FCS) continuously monitors the pilot's manoeuvres and once it detects that the current manoeuvre if continued for some more seconds could lead to a low-speed departure, it gives a warning to the pilot to take corrective action.

However, in case the pilot ignores this warning the auto-low speed recover function automatically takes over control of the aircraft and recovers it to a safe condition in the shortest possible time.

2. Disorientation Recovery Function (DRF)

Pilots may get disoriented at times while flying into clouds or while flying over the sea. In such situations, a switch (panic button) is provided in the cockpit.

If pressed by the pilot, the FCS takes over the controls and recovers the aircraft to level flight optimally (with minimum loss of speed or altitude). Thus while the auto low speed recovery mode cuts in automatically, the DRF mode is engaged by the pilot when he needs it.


These are additional modes and add ons to the LCA state-of-the-art digital FBW quad redundant flight control system that guarantees complete carefree manoeuvring of the aircraft. In a conventional dogfight situation, the fighter jets need to perform extreme manoeuvres. To enable the pilot to concentrate on his combat task, the LCA fly-by-wire system automatically limits the aircraft parameters to ensure no departure from controlled flight and also ensures that none of the structural limits of the aircraft are exceeded while in combat or otherwise.


Note : jf17 bk 1,2,3 does not have it

 

[porky_kicker]

RELAXED STATIC STABILITY ( RSS )

All 4th and 5th generation fighters have RSS based design ( except for JF17 and yet idiots call it a 4th generation aircraft )

In simple words the aircraft is designed to be aerodynamically unstable.

LCA IS A RSS DESIGN ie LCA IS AN AERODYNAMICALLY UNSTABLE AIRCRAFT

RSS changes the dynamics of the aircraft while dramatically enhancing its maneuvering capabilities.

Implementing relaxed static stability means that the center of lift will forward of the center of gravity instead of aft of it and as a result the aircraft will be statically unstable.

Also static stability is proportional to the control forces, therefor reducing stability gives pilots more response for the same effort.

RSS is also called reduced static longitudinal static stability. longitudinal static stability can be measured as the relative distance between neutral point and the center of gravity.

An aircraft with RSS design will have the center of gravity aft of the neutral point. (the neutral point is that point along the path of the center of gravity movement where the stick force per knot drops to zero and increases in either direction.)

As we shift the center of gravity aft of the neutral point , stability is lost and the aircraft will start deviating from its trimmed state.so shifting the center of gravity back gives us a more responsive and maneuverable aircraft but with the added risk of uncontrollable behavior which cannot be contained by manual input. however this behavior is useful if we want high angle changes and even high AOA quickly.

An unstable aircraft only needs minimal kick and will do the rest of the maneuver all by itself. it is also helps to reduce the inertias particularly around the role axis for a faster response.maneuvers are instantaneous initiated and most importantly precisely controlled.

Also deliberately designed unstable aircrafts require smaller control deflections to initiate maneuvering , as a result drag and control surface imposed stresses is reduced and aircraft responsiveness is also enhanced.

RSS configured aircrafts are near impossible to control by pilot input, so an artificial stability is imposed by using computers , servos and sensors as parts of a fully digital fly by wire (FBW) control system working in all the three axis that is pitch, yaw and roll.

 

[porky_kicker]

F16 was the first aircraft in which RSS was implemented and to control the resultant unstable characteristics of F16 , the concept of digital fly by wire (FBW) was also for the first time implemented in F16.

Advantages of RSS design coupled with FULL digital FBW are

1. it provides good handling capability

2. it also provides invariant response with respect to variations in aerodynamics , fuel etc and facilitates robust performance.

3. it enables the pilot to fly the mission without worrying about exceeding of flight parameters beyond the safe limits.in flight safety is increased.

4. precise response control , reduced lag and overshoots results in vastly improved response and tracking accuracy of the pilot airframe system.

Also ONLY RSS design based aircrafts with tri/quad redundant digital FBW can implement additional highly redundant fail safe advanced safety modes like

1. auto low-speed recovery (ALSR) incase of impending stall during nap of the earth missions or low speed maneuvers etc. The aircraft automatically takes control and recovers the aircraft.

2. Disorientation recovery mode (DRM) to fight pilot disorientation in the high seas ( a common cause for crash at sea ) or in the clouds etc. When the Pilot gets disoriented in such situations, he can press a switch (panic button) provided in the cockpit then the aircraft takes over the controls and recovers itself to level flight optimally (with minimum loss of speed or altitude).

Etc

Modern aircrafts with RSS design and fully digital FBW are F16, Gripen, Rafale, LCA Tejas, J10, F22, F35, PAKFA, J20, F18, Typhoon , T50, F-2, FCK-1

ONLY EXCEPTION IS JF17

 

[porky_kicker]

FC1/JF 17 is a fighter aircraft whose base design is aerodynamically stable, that is - its design is not RSS based.

And the reason why FC1/JF17 came out with analogue flight controls and later a hybrid flight control system and then later according to news reports the JF17B twin seater came with full digital FBW. And then FC1/JF17 BK 3 .

The advantages of implementing FBW in a aerodynamically stable ( non RSS ) aircraft is MINIMAL ie for a slight reduction in size , weight and power (SWaP) parameters only. Reason why it was necessitated in twin seater JF17 B in the first place , additional weight added due to extra pilot needed to compensated by removal of analogue flight control system.

But it will not increase the aerodynamic performance , superior handling capabilities , stable invariant response etc as compared to a fighter aircraft with a FBW designed to go hand in hand with its inherent aerodynamically unstable RSS design from the design stage itself. So JF17 bk 3 is still a dud in flight performance with no advantage over Jf17 bk 1/2.

So when the porkies and gullible Indians claim that FC1/JF17 ( any block ) is comparable to LCA , It is hilarious , because in the aerodynamic , kinematic , maneuverablity , handling , responsiveness , flight safety etc parameters it will never come close to LCA.

For that to happen they will need to redesign FC1/JF17 from scratch and implement a RSS design to go along with a full FBW.

And the main reasons why the PLAAF refused to induct FC1/JF17 themselves. (J10 aircraft on the other hand is based on RSS design with a full FBW flight control system since its first flight.)

 

[porky_kicker]

LCA MK1 sports hybrid MMR - Multi Mode Radar ( Isreali EL/M-2032 ) front end Israeli and back end Indian.

It features look-up/look-down/shoot-down modes, low/medium/high pulse repetition frequencies (PRF), platform motion compensation, doppler beam-sharpening, moving target indication(MTI), Doppler filtering, constant false alarm rate (CFAR) detection, range-Doppler ambiguity resolution, scan conversion, and online diagnostics to identify faulty processor modules.

Range 150 km.

 

[porky_kicker]

Hot refueling is a single point pressure refueling of the aircraft with the engine in operation. It is a process by which a fighter aircraft is refueled (in between sorties) while its engine is in operation, thereby cutting down refueling time by half and turn-around time significantly.

LCA is fully certified for hot refueling.

JF17/FC1 be it bk 1,2,3 on the other hand can't.

 

[porky_kicker]

LCA has a advanced utility and health management system which provides system health and warnings to the pilot through the open architecture computer ( OAC ).

 

[porky_kicker]

Hot refueling refers to refueling the aircraft when the pilot is in the aircraft loaded with weapons and with the engine running. Not many operational aircraft's presently flying worldwide have this capability.

Another thing, in LCA this also involves fitting "pressure refueling" of the kind that exists in Formula One racing cars, which requires fuel to be pumped very rapidly under high pressure into the fuel tanks.

LCA IOC version it takes just four minutes, and two more to fill drop tanks as well.

This time requirement is expected to come down considerably in the future with FOC and MK1A version.

 

[Bleh]

Tejas FOC version is the heaviest of LCA class. At 7000kg it's bordering on light-medium category.

Presently its max. payload is 3900kg & MTOW 14240kg... If empty weight reduces in Mark1A due to internal re-engineering, then payload should reach/surpass 4000kg.