ADA Tejas (LCA) News and Discussions

[pmaitra]

I remember very clearly discussing this several years ago and still the Aeronautical Development Agency's publicity department (or whatever they call it) continues to repeat the same old shtick. This time, they are packaging Close Air Support as Battle Field Air Support.

 

[ersakthivel]

Good explanation. I have one question. What is the source of this information below?

http://www.tejas.gov.in/technology/fly_by_wire.html

Tejas is equipped with a quadruplex digital fly-by-wire flight control system to ease handling by the pilot. The digital FBW system of the Tejas employs a powerful digital flight control computer (DFCC) comprising four computing channels, each with its own independent power supply and all housed in a single LRU. The DFCC receives signals from a variety of sensors and pilot control stick inputs, and processes these through the appropriate channels to excite and control the elevons, rudder and leading edge slat hydraulic actuators. The DFCC channels are built around 32-bit microprocessors and use a subset of the Ada programming language for software implementation. The computer interfaces with pilot display elements like the MFDs through MIL-STD-1553B multiplex avionics data buses and RS-422 serial links.

Tejas is intentionally made longitudinally unstable to enhance manoeuvrability. The Control laws (CLAW) recover Stability and provide good Handling Qualities to the Pilot. They also provide invariant response with respect to variation in aerodynamics, fuel etc. and facilitate robust performance. The CLAW is carefree and ensures that various aircraft parameters are limited automatically. This enables the pilot to fly the mission without worrying about exceedance of parameters beyond a safe limit.

The autopilot provides pilot relief functions. This helps the pilot to do more head down activities (especially mission critical activities) without being concerned about the aircraft departing from its flight path. The autopilot is also equipped with advanced features like auto level (which helps the pilot recover the aircraft if he gets disoriented and also during night flying), safe altitude recovery (which automatically pulls up the aircraft if it comes too close to the ground) and navigation modes (which steer the aircraft automatically along a pre-determined flight path).

Besides three different versions of Tejas are flying with the RSS 4 channel all digital fly by wire system, with slightly different airframes,

1.Naval Tejas with LEVCONs,

2.Trainer with two seater arrangement,

3.Airforce tejas, without LEVCONs which is the older version.

 

[pmaitra]

http://www.tejas.gov.in/technology/fly_by_wire.html



Besides three different versions of Tejas are flying with the RSS 4 channel all digital fly by wire system, with slightly different airframes,

1.Naval Tejas with LEVCONs,

2.Trainer with two seater arrangement,

3.Airforce tejas, without LEVCONs which is the older version.

Thank you. The rest of the information is fine.

This is what the source says:

Tejas is intentionally made longitudinally unstable to enhance manoeuvrability.

This is what you said:

In a cutting edge Relaxed Static Stability 4 channel ,all digital fly by wire software operated flight control system like tejas,

It looks like the plane itself is not stable w.r.t. pitch. It is the Control Laws that maintain ("recover" [sic.]) stability.

Static Relaxed Stability

I am not very sure where the CG of the aircraft lies. If it has static relaxed stability, it means the CG would be ahead of the CL. However, given that Control Laws are used to maintain the pitch of the aircraft and that the aircraft is longitudinally unstable, I suspect the CG is very close to or on the CL.

It would be interesting to learn where exactly the CG lies w.r.t. the CL, but then again, with so many versions of LCA being developed with different types of equipment, one couldn't be sure what applies to which version.

 

[ersakthivel]

Don't count your chickens yet. What if Kaveri ultimately meets the requirements and in doing so, increases in size/length?

World over improvement in her engine technology relies on ,

increasing TET (Turbine Entry Temperature) by improving metallurgy of the core hot section, increasing operating pressure ratios & dropping engine stages.

All these generally yield a lighter weight engine , which generates more thrust by increased thermodynamic efficiency.

 

[ersakthivel]

Thank you. The rest of the information is fine.

This is what the source says:


This is what you said:


It looks like the plane itself is not stable w.r.t. pitch. It is the Control Laws that maintain ("recover" [sic.]) stability.

Static Relaxed Stability
View attachment 21888

I am not very sure where the CG of the aircraft lies. If it has static relaxed stability, it means the CG would be ahead of the CL. However, given that Control Laws are used to maintain the pitch of the aircraft and that the aircraft is longitudinally unstable, I suspect the CG is very close to or on the CL.

It would be interesting to learn where exactly the CG lies w.r.t. the CL, but then again, with so many versions of LCA being developed with different types of equipment, one couldn't be sure what applies to which version.

CL is in font of CG in all Relaxed Static Stability fly by wire airframes.

In tejas too CL is in font of CG,

This enables the fighter to pitch up instantly in close combat, when pilots manoeuvre it.

This leads to higher G onset rates & higher Instantaneous Turn Rates , critical in close combat survivability & missile evasion.

Only mirage(lesser powered ,analog tech) has such RSS tech in IAF.
I am sure about IAF Tejas version.

But trainers too should hv such arrangement , to be meaning ful. But I hv no source about it & naval tejas

 

[Kunal Biswas]

Loiter time is very valuable in CAS, Troops require ground support in frequent manner ..

The aircraft make strike runs and loiter at designated altitude before its called again for ground strikes ..

I remember very clearly discussing this several years ago and still the Aeronautical Development Agency's publicity department (or whatever they call it) continues to repeat the same old shtick. This time, they are packaging Close Air Support as Battle Field Air Support.

View attachment 21887

 

[ersakthivel]

Are you sure about the length of 414?

 

[Kunal Biswas]

R-73 AAM at display

Debry BVR at display

Laser guided bomb at display

LGB and Dumb bomb at display, I cannot make out far right yellow tip projectile .. ?

Singapore Defense Minister getting ready for flight.

Singapore Defense Minister after the flight.

Singapore`s military aviators and enggs at the base, The aircraft at rear is a SU-30MKI.

Singapore Defense Minister Ng Eng Hen Visits Training at Kalaikunda Air Force Station

Missiles sit on the tarmac in front of an Indian Air Force (IAF) Tejas fighter jet, developed by Hindustan Aeronautics Ltd., at the Kalaikunda Air Force Station, West Bengal, India, on Tuesday, Nov. 28, 2017. Singapore's Defense Minister Ng Eng Hen is scheduled to speak in New Delhi at a Brookings India event on the subject of India-Singapore security relations. Photographer: Anindito Mukherjee/Bloomberg via Getty Images

 

[pmaitra]

Loiter time is very valuable in CAS, Troops require ground support in frequent manner ..

The aircraft make strike runs and loiter at designated altitude before its called again for ground strikes ..

• "Loiter time is very valuable in CAS." - Agree.
• "Troops require ground support in frequent manner." - Agree.
• "The aircraft make strike runs and loiter at designated altitude before its called again for ground strikes .." Agree if the aircraft is a straight wing aircraft. Disagree if it is a delta wing aircraft.

Two most widely used CAS aircraft are Fairchild Republic A-10 and Sukhoi-25. None of them are delta-wing.

On the other hand, I have not seen any major military power use Mirage-2000, MiG-21, or something that looks like LCA for CAS.

__________________

Swept wing and delta-wing are good for high-speed.
Straight wing is good for low speed.

High Speed Aircraft usually have swept wing or delta wing.

Examples:

MiG-17

F-86

Aérospatiale/BAC Concorde

Tupolev-144

Low Speed Aircraft usually have straight wing:

Fairchild Republic A-10

Sukhoi-25

Hybrid High-Speed and Low-Speed is achieved by variable geometry wings. In other words, these aircraft can be both straight wing as well as swept wing.

Tupolev-160

Rockwell B-1

 

[Kunal Biswas]

In Indian context, during Kargil War MIG-21 and Mirage 2000 both took part in CAS, MIG-21 is doing this role since 71 war ..

These are not dedicated ground attack fighters but multi-role in nature, This leads to design trade off which gives it capability of conducting CAS but not a fully fledged CAS aircraft ..

• "Loiter time is very valuable in CAS." - Agree.
• "Troops require ground support in frequent manner." - Agree.
• "The aircraft make strike runs and loiter at designated altitude before its called again for ground strikes .." Agree if the aircraft is a straight wing aircraft. Disagree if it is a delta wing aircraft.

Two most widely used CAS aircraft are Fairchild Republic A-10 and Sukhoi-25. None of them are delta-wing.

On the other hand, I have not seen any major military power use Mirage-2000, MiG-21, or something that looks like LCA for CAS.

 

[Kshithij]

• "Loiter time is very valuable in CAS." - Agree.
• "Troops require ground support in frequent manner." - Agree.
• "The aircraft make strike runs and loiter at designated altitude before its called again for ground strikes .." Agree if the aircraft is a straight wing aircraft. Disagree if it is a delta wing aircraft.

Two most widely used CAS aircraft are Fairchild Republic A-10 and Sukhoi-25. None of them are delta-wing.

On the other hand, I have not seen any major military power use Mirage-2000, MiG-21, or something that looks like LCA for CAS.

__________________

Swept wing and delta-wing are good for high-speed.
Straight wing is good for low speed.

High Speed Aircraft usually have swept wing or delta wing.

Examples:

View attachment 21897
MiG-17

View attachment 21898
F-86

Aérospatiale/BAC Concorde

Tupolev-144

Low Speed Aircraft usually have straight wing:

Fairchild Republic A-10

Sukhoi-25

Hybrid High-Speed and Low-Speed is achieved by variable geometry wings. In other words, these aircraft can be both straight wing as well as swept wing.

Tupolev-160

Rockwell B-1

You are mistaking the strength of a design to its role. A delta wing has strength in terms of -
1) better fuel efficiency and control in transonic and supersonic speed (0.8Mach+)
2) higher instantaneous turn rates (but lower sustained turn rates)
3) rigidity of design ensure that composite usage can be much higher. Metal usage can be lowered as the design itself has inherent rigidity.

But, this doesn't mean it can't be used for ground attack. With older planes and dumb bombs, this might have been the case. But with guided bombs, the ground attack roles have become much easier and accurate. It is better to have a fighter jet that is more focused on air-air ability than air to ground ability. Ground targets are much slower and mostly static while air targets require higher focus to dogfight, evade missiles and prevent infiltration.

By this logic, a delta wing aircraft is actually better suited for multirole mission than a fighter like F16.

PS- dumb bombs are no longers meaningful. We saw in Kargil how these dumb bombs had a hit rate of 2%. Guided bombs are now simpler to make with Indian IRNSS system based guidance. It requires minimum addition in terms if gliding foldable wings and GOS receivers and doesn't cost much either

 

[rohit b3]

http://www.hal-india.com/Product_Details.aspx?Mkey=54&lKey=&CKey=20

According to this on the HAL Website, Tejas's combat radius is 300 kms, but payload is 5.3 tons.

Even though im sure this info is old, does that mean that Tejas can carry more weapons by sacrificing fuel? For instance 5 tons weapons with 50% fuel?

 

[Kunal Biswas]

The HAL report was quoting some older prototype specifications, This is a PIB report from Tejas IOC-2 ceremony, Its stated that its combat radius upto 500kms and payload is certainly not 5000kgs but Tejas MK-1 can just about carry 4000 kgs of payload realistically.

Please refer to this regarding ferry range and combat radius, with payload specification which are posted in last few pages ..

 

[Sancho]

Disagree if it is a delta wing aircraft.
Two most widely used CAS aircraft are Fairchild Republic A-10 and Sukhoi-25. None of them are delta-wing.

On the other hand, I have not seen any major military power use Mirage-2000, MiG-21, or something that looks like LCA for CAS.

You are mixing up 2 things here. Once the design for CAS specific fighters and secondly the CAS capability of multi role fighters.

CAS fighters are designed for that specific role only, the aim then will be on load, slow speed manuverability or low level performance. Multi role fighters on the other hand, are designed for air combats and geared for a secondary strike capability (some fighters more than others).
I showed it recently in this very thread (sadly the post was moved), that LCA can carry the same LGB strike load as a Jaguar that was designed for strike. So today any modern fighter can do CAS even with delta wing designs.

 

[tejas warrior]

#TejasUpdate #1 | 7 Dec 2017 | #Tarmak007

As a run-up to the FOC in 2018, #Tejas LSP-8 is optimising flight profiles with the in-flight refueling probe (IFR). Air-to-air refueling trials will begin early 2018. First dry contact followed by wet trials. So far, LSP-8 flew 44 sorties with IFR. #DNKT

 

[kamaal]

#TejasUpdate #1 | 7 Dec 2017 | #Tarmak007

As a run-up to the FOC in 2018, #Tejas LSP-8 is optimising flight profiles with the in-flight refueling probe (IFR). Air-to-air refueling trials will begin early 2018. First dry contact followed by wet trials. So far, LSP-8 flew 44 sorties with IFR. #DNKT

View attachment 21904

Though very happy with the IFR development but the current design does block pilot's view. It should have been little on the right side to avoid disturbance.

I think there is some electronic equipment blocking the right side of the nose cone, may be the Radar or something else.

 

[Kshithij]

Though very happy with the IFR development but the current design does block pilot's view. It should have been little on the right side to avoid disturbance.

I think there is some electronic equipment blocking the right side of the nose cone, may be the Radar or something else.

I don't think that black protruding object is a test equipment. I don't think refueling pods are like that. I am not sure though

 

[kamaal]

I don't think that black protruding object is a test equipment. I don't think refueling pods are like that. I am not sure though

Your skepticism is right the pic is photoshoped.
Here is original LSP with IFR probe. The probe starts from little center of the nose cone and then it is angled towards right, which is probably the best HAL could do with such small space to work on.
I don't know how many flight test will it take to start refueling test.

 

[darshan978]

Your skepticism is right the pic is photoshoped.
Here is original LSP with IFR probe. The probe starts from little center of the nose cone and then it is angled towards right, which is probably the best HAL could do with such small space to work on.
I don't know how many flight test will it take to start refueling test.

Isnt it mock up?...........................

 

[wuzetian]

When is Tejas FOC ?

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