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ADA Tejas (LCA) News and Discussions
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some stuff p2 prada you can read at leissure.
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading.
Correspondingly, the landing and take-off speeds will be higher. The high wing loading also decreases maneuverability. The same constraints apply to winged biological organisms.
Effect on performance
Wing loading is a useful measure of the general maneuvering performance of an aircraft. Wings generate lift owing to the motion of air over the wing surface. Larger wings move more air, so an aircraft with a large wing area relative to its mass (i.e., low wing loading) will have more lift available at any given speed.
Therefore, an aircraft with lower wing loading will be able to take-off and land at a lower speed (or be able to take off with a greater load). It will also be able to turn faster.
Effect on take-off and landing speeds
As a consequence, aircraft with the same CL at take-off under the same atmospheric conditions will have take off speeds proportional to . So if an aircraft's wing area is increased by 10% and nothing else changed, the take-off speed will fall by about 5%. Likewise, if an aircraft designed to take off at 150 mph grows in weight during development by 40%, its take-off speed increases to mph.
Effect on climb rate and cruise performance
Wing loading has an effect on an aircraft's climb rate. A lighter loaded wing will have a superior rate of climb compared to a heavier loaded wing as less airspeed is required to generate the additional lift to increase altitude.
A lightly loaded wing has a more efficient cruising performance because less thrust is required to maintain lift for level flight. However, a heavily loaded wing is more suited for higher speed flight because smaller wings offer less drag.
The wing loading is important in determining how rapidly the climb is established. If the pilot increases the speed to vc the aircraft will begin to rise with vertical acceleration ac because the lift force is now greater than the weight.
Effect on turning performance
To turn, an aircraft must roll in the direction of the turn, increasing the aircraft's bank angle. Turning flight lowers the wing's lift component against gravity and hence causes a descent. To compensate, the lift force must be increased by increasing the angle of attack by use of up elevator deflection which increases drag.
Turning can be described as 'climbing around a circle' (wing lift is diverted to turning the aircraft) so the increase in wing angle of attack creates even more drag. The tighter the turn radius attempted, the more drag induced, this requires that power (thrust) be added to overcome the drag. The maximum rate of turn possible for a given aircraft design is limited by its wing size and available engine power: the maximum turn the aircraft can achieve and hold is its sustained turn performance.
As the bank angle increases so does the g-force applied to the aircraft, this has the effect of increasing the wing loading and also the stalling speed. This effect is also experienced during level pitching maneuvers.
Aircraft with low wing loadings tend to have superior sustained turn performance because they can generate more lift for a given quantity of engine thrust. The immediate bank angle an aircraft can achieve before drag seriously bleeds off airspeed is known as its instantaneous turn performance. An aircraft with a small, highly loaded wing may have superior instantaneous turn performance, but poor sustained turn performance: it reacts quickly to control input, but its ability to sustain a tight turn is limited.
A classic example is the F-104 Starfighter, which has a very small wing and high wing loading. At the opposite end of the spectrum was the gigantic Convair B-36. Its large wings resulted in a low wing loading, and there are disputed claims[who?] that this made the bomber more agile than contemporary jet fighters (the slightly later Hawker Hunter had a similar wing loading of 250 kg/m2) at high altitude. Whatever the truth of that, the delta winged Avro Vulcan bomber, with a wing loading of 260 kg/m2 could certainly be rolled at low altitudes.
Like any body in circular motion, an aircraft that is fast and strong enough to maintain level flight at speed v in a circle of radius R accelerates towards the centre at . That acceleration is caused by the inward horizontal component of the lift, , where is the banking angle. Then from Newton's second law,
Tidying up gives
The smaller the wing loading, the tighter the turn.
Gliders designed to exploit thermals need a small turning circle in order to stay within the rising air column, and the same is true for soaring birds.
Other birds, for example those that catch insects on the wing also need high maneuverability. All need low wing loadings.
Effect on stability
Wing loading also affects gust response, the degree to which the aircraft is affected by turbulence and variations in air density. A small wing has less area on which a gust can act, both of which serve to smooth the ride. For high-speed, low-level flight (such as a fast low-level bombing run in an attack aircraft), a small, thin, highly loaded wing is preferable: aircraft with a low wing loading are often subject to a rough, punishing ride in this flight regime.
Effect of development
A further complication with wing loading is that it is difficult to substantially alter the wing area of an existing aircraft design (although modest improvements are possible). As aircraft are developed they are prone to "weight growth" -- the addition of equipment and features that substantially increase the operating mass of the aircraft. An aircraft whose wing loading is moderate in its original design may end up with very high wing loading as new equipment is added. Although engines can be replaced or upgraded for additional thrust, the effects on turning and take-off performance resulting from higher wing loading are not so easily reconciled.
to sum it up
1.The smaller the wing loading, the tighter the turn.
2. For high-speed, low-level flight (such as a fast low-level bombing run in an attack aircraft), a small, thin, highly loaded wing is preferable[/U]: aircraft with a low wing loading are often subject to a rough, punishing ride in this flight regime.It is to compensate for this problem, the LCA has cranked delta which improves handling at low altitude.LEVCONS are planned to aid more in this regard..
3The maximum rate of turn possible for a given aircraft design is limited by its wing size and available engine power, the maximum turn the aircraft can achieve and hold is its sustained turn performance
4. Wing loading is a useful measure of the general maneuvering performance of an aircraft
5. Larger wings move more air, so an aircraft with a large wing area relative to its mass (i.e., low wing loading) will have more lift available at any given speed.
6.Wing loading has an effect on an aircraft's climb rate. A lighter loaded wing will have a superior rate of climb compared to a heavier loaded wing as less airspeed is required to generate the additional lift to increase altitude.
7. A lightly loaded wing has a more efficient cruising performance because less thrust is required to maintain lift for level flight. However, a heavily loaded wing is more suited for higher speed flight because smaller wings offer less drag.
That is why from mirage onwards to LCA,TYPHOON,RAFALE,GRIPPEN,F-22,F-35,PAKFA ARE ALL GOING FOR LOW WING LOADING DELAT DESIGN.THE LCA TEJAS HAS THE LOWEST WING LOADING OF ALL.IT IS NOT SOME INSIGNIFICAT STUFF.
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading.
Correspondingly, the landing and take-off speeds will be higher. The high wing loading also decreases maneuverability. The same constraints apply to winged biological organisms.
Effect on performance
Wing loading is a useful measure of the general maneuvering performance of an aircraft. Wings generate lift owing to the motion of air over the wing surface. Larger wings move more air, so an aircraft with a large wing area relative to its mass (i.e., low wing loading) will have more lift available at any given speed.
Therefore, an aircraft with lower wing loading will be able to take-off and land at a lower speed (or be able to take off with a greater load). It will also be able to turn faster.
Effect on take-off and landing speeds
As a consequence, aircraft with the same CL at take-off under the same atmospheric conditions will have take off speeds proportional to . So if an aircraft's wing area is increased by 10% and nothing else changed, the take-off speed will fall by about 5%. Likewise, if an aircraft designed to take off at 150 mph grows in weight during development by 40%, its take-off speed increases to mph.
Effect on climb rate and cruise performance
Wing loading has an effect on an aircraft's climb rate. A lighter loaded wing will have a superior rate of climb compared to a heavier loaded wing as less airspeed is required to generate the additional lift to increase altitude.
A lightly loaded wing has a more efficient cruising performance because less thrust is required to maintain lift for level flight. However, a heavily loaded wing is more suited for higher speed flight because smaller wings offer less drag.
The wing loading is important in determining how rapidly the climb is established. If the pilot increases the speed to vc the aircraft will begin to rise with vertical acceleration ac because the lift force is now greater than the weight.
Effect on turning performance
To turn, an aircraft must roll in the direction of the turn, increasing the aircraft's bank angle. Turning flight lowers the wing's lift component against gravity and hence causes a descent. To compensate, the lift force must be increased by increasing the angle of attack by use of up elevator deflection which increases drag.
Turning can be described as 'climbing around a circle' (wing lift is diverted to turning the aircraft) so the increase in wing angle of attack creates even more drag. The tighter the turn radius attempted, the more drag induced, this requires that power (thrust) be added to overcome the drag. The maximum rate of turn possible for a given aircraft design is limited by its wing size and available engine power: the maximum turn the aircraft can achieve and hold is its sustained turn performance.
As the bank angle increases so does the g-force applied to the aircraft, this has the effect of increasing the wing loading and also the stalling speed. This effect is also experienced during level pitching maneuvers.
Aircraft with low wing loadings tend to have superior sustained turn performance because they can generate more lift for a given quantity of engine thrust. The immediate bank angle an aircraft can achieve before drag seriously bleeds off airspeed is known as its instantaneous turn performance. An aircraft with a small, highly loaded wing may have superior instantaneous turn performance, but poor sustained turn performance: it reacts quickly to control input, but its ability to sustain a tight turn is limited.
A classic example is the F-104 Starfighter, which has a very small wing and high wing loading. At the opposite end of the spectrum was the gigantic Convair B-36. Its large wings resulted in a low wing loading, and there are disputed claims[who?] that this made the bomber more agile than contemporary jet fighters (the slightly later Hawker Hunter had a similar wing loading of 250 kg/m2) at high altitude. Whatever the truth of that, the delta winged Avro Vulcan bomber, with a wing loading of 260 kg/m2 could certainly be rolled at low altitudes.
Like any body in circular motion, an aircraft that is fast and strong enough to maintain level flight at speed v in a circle of radius R accelerates towards the centre at . That acceleration is caused by the inward horizontal component of the lift, , where is the banking angle. Then from Newton's second law,
Tidying up gives
The smaller the wing loading, the tighter the turn.
Gliders designed to exploit thermals need a small turning circle in order to stay within the rising air column, and the same is true for soaring birds.
Other birds, for example those that catch insects on the wing also need high maneuverability. All need low wing loadings.
Effect on stability
Wing loading also affects gust response, the degree to which the aircraft is affected by turbulence and variations in air density. A small wing has less area on which a gust can act, both of which serve to smooth the ride. For high-speed, low-level flight (such as a fast low-level bombing run in an attack aircraft), a small, thin, highly loaded wing is preferable: aircraft with a low wing loading are often subject to a rough, punishing ride in this flight regime.
Effect of development
A further complication with wing loading is that it is difficult to substantially alter the wing area of an existing aircraft design (although modest improvements are possible). As aircraft are developed they are prone to "weight growth" -- the addition of equipment and features that substantially increase the operating mass of the aircraft. An aircraft whose wing loading is moderate in its original design may end up with very high wing loading as new equipment is added. Although engines can be replaced or upgraded for additional thrust, the effects on turning and take-off performance resulting from higher wing loading are not so easily reconciled.
to sum it up
1.The smaller the wing loading, the tighter the turn.
2. For high-speed, low-level flight (such as a fast low-level bombing run in an attack aircraft), a small, thin, highly loaded wing is preferable[/U]: aircraft with a low wing loading are often subject to a rough, punishing ride in this flight regime.It is to compensate for this problem, the LCA has cranked delta which improves handling at low altitude.LEVCONS are planned to aid more in this regard..
3The maximum rate of turn possible for a given aircraft design is limited by its wing size and available engine power, the maximum turn the aircraft can achieve and hold is its sustained turn performance
4. Wing loading is a useful measure of the general maneuvering performance of an aircraft
5. Larger wings move more air, so an aircraft with a large wing area relative to its mass (i.e., low wing loading) will have more lift available at any given speed.
6.Wing loading has an effect on an aircraft's climb rate. A lighter loaded wing will have a superior rate of climb compared to a heavier loaded wing as less airspeed is required to generate the additional lift to increase altitude.
7. A lightly loaded wing has a more efficient cruising performance because less thrust is required to maintain lift for level flight. However, a heavily loaded wing is more suited for higher speed flight because smaller wings offer less drag.
That is why from mirage onwards to LCA,TYPHOON,RAFALE,GRIPPEN,F-22,F-35,PAKFA ARE ALL GOING FOR LOW WING LOADING DELAT DESIGN.THE LCA TEJAS HAS THE LOWEST WING LOADING OF ALL.IT IS NOT SOME INSIGNIFICAT STUFF.
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Beyond Visual Range Air to Air Missile (BVRAAM)
MORE SOURCE FOR HOW A BVR CAN RELY ON AWACS FOR GUIDANCE IRRELEVANT OF LAUNCHING LCA TEJAS FROM TH ABOVE LINK.
A single fighter, equipped with an operational load of BVRAAM missiles, has the potential to destroy even the most maneuvrable of fighters well before they reach combat range, and simultaneously engage bombers at long range. Targets are prioritised prior to launch, and the missiles are fired towards the predicted interception points. Meanwhile target information can be updated, via the data-link, throughout the initial flight - either from the launch aircraft or from a third party such as AWACs. Tactical information on the missile can also be received by the controlling aircraft. At the appropriate time, BVRAAM�s active radar seeker autonomously searches for and locks onto the target. The missile is now fully autonomous, making its own decisions to home in on the target, despite any evasive manoeuvres, or decoys or sophisticated electronic countermeasures.
MORE SOURCE FOR HOW A BVR CAN RELY ON AWACS FOR GUIDANCE IRRELEVANT OF LAUNCHING LCA TEJAS FROM TH ABOVE LINK.
A single fighter, equipped with an operational load of BVRAAM missiles, has the potential to destroy even the most maneuvrable of fighters well before they reach combat range, and simultaneously engage bombers at long range. Targets are prioritised prior to launch, and the missiles are fired towards the predicted interception points. Meanwhile target information can be updated, via the data-link, throughout the initial flight - either from the launch aircraft or from a third party such as AWACs. Tactical information on the missile can also be received by the controlling aircraft. At the appropriate time, BVRAAM�s active radar seeker autonomously searches for and locks onto the target. The missile is now fully autonomous, making its own decisions to home in on the target, despite any evasive manoeuvres, or decoys or sophisticated electronic countermeasures.
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MORE FROM WIKI PEDIA ON AMRAAM YOUR FAVOURITE, P2prada
Interception course stage
Grumman F-14 Tomcat carrying an AMRAAM during a 1982 test
AMRAAM uses two-stage guidance when fired at long range. The aircraft passes data to the missile just before launch, giving it information about the location of the target aircraft from the launch point and its direction and speed. The missile uses this information to fly on an interception course to the target using its built in inertial navigation system (INS). This information is generally obtained using the launching aircraft's radar, although it could come from an infrared search and tracking system (IRST), from a data link from another fighter aircraft, or from an AWACS aircraft.
SURPRISE SURPRISE THE AMRAAM CAN USE INFO FROM IRST TO HOME IN.YOU WERE DENYING IT ALL ALONG.
YOU HAVE CONSISTENLY MAINTAINED THAT NO IRST CAN GUIDE THE MISSILE!!!!!!!!!!!!!!!!!!!!!!!!!!
THE FOLLOWING IS YOUR GROUND BREAKING THEORY ON IRST
Interception course stage
Grumman F-14 Tomcat carrying an AMRAAM during a 1982 test
AMRAAM uses two-stage guidance when fired at long range. The aircraft passes data to the missile just before launch, giving it information about the location of the target aircraft from the launch point and its direction and speed. The missile uses this information to fly on an interception course to the target using its built in inertial navigation system (INS). This information is generally obtained using the launching aircraft's radar, although it could come from an infrared search and tracking system (IRST), from a data link from another fighter aircraft, or from an AWACS aircraft.
SURPRISE SURPRISE THE AMRAAM CAN USE INFO FROM IRST TO HOME IN.YOU WERE DENYING IT ALL ALONG.
YOU HAVE CONSISTENLY MAINTAINED THAT NO IRST CAN GUIDE THE MISSILE!!!!!!!!!!!!!!!!!!!!!!!!!!
THE FOLLOWING IS YOUR GROUND BREAKING THEORY ON IRST
After launch, If the firing aircraft or surrogate continues to track the target, periodic updates—such as changes in the target's direction and speed—are sent from the launch aircraft to the missile, allowing the missile to adjust its course so that it is able to close to a self-homing distance where it will be close enough to "catch" the target aircraft in the basket (the missile's radar field of view in which it will be able to lock onto the target aircraft, unassisted by the launch aircraft).
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See there is no point in advertising your presence to enemy just for the sake of longer range tracking.In practice other than AWACS fighters will try to remain radio silent and try to rely as much on awacs and ew craft for targeting. Because stealth and surprise is more importanat for enemy fighter. for your information LCA wont be cheap.Other than range it is as costly or as sophisticated as any other fighter IAF will have.
MKI is more of a strike fighter,but LCA is mostly a point defence fighter that should have the least RCS possible and high agility in high altitudes himalayan region.It's lower RCS gives it an edge over any other single engined 4.5 gen fighter in the world, in the same way RAFALE's lower RCs gives it an edge over sukhoi.,The IAF gave an initial order of 40 only.Then they later added another 20.Havent you read any test pilot testimonials. They say it handles sharper than mirage. The IAF is spending 1.5 billion dollar just to upgrade the mirage,which will be inferior in comparision to TEJAs's LOW wing loading and high TWR.It is modular and upgradble as desired.Don't expect the russians to upgrade SUKHOI at material cost without charging for R&D from the tech of PAKFA.
ALso it will get ASEA radar , ring laser gyros and all electrical actuators in place of heavy hydraulic actuators and if possible the fly by light FCS and the most modern engine developed for AMCA in it's upgrade.Then it will be one of the unbeatable bird in sky.The sukhois and RAFALES wont get them with least cost or may not get them at all,because unlike ADA they will charge like hell for R&D.The mirage upgrades alone is equal to the cost of new fighter. ISRo and DRDO already have the ring laser gyro tech for their missiles and launch vehicles.All electrical actuators will make it lighter and nimbler.
In mk-III can be a 10 ton double engined version with excellent TWr and internal bomb bay for stealth.If you have any doubt please read "INDIA TODAY "article on LCA by "MANOHAR JOSHI"----"OUR CINDRELLA MUST STEP OUT"..IT HAS HUGE EXPORT POTENTIAL IN MK-II VERSION IF GTRE-SNECMA ENGINE ARRIVES IN A FEW YEARS FOR AMCA.Because once that engine is added it will have nil american content and will be hugely attractive for export customers free from the influence of AMERICANS.
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Tarmak007 -- A bold blog on Indian defence: TOP GUN: National honour for Tejas Test pilot Suneet
you will see the test pilot suneet krishna's credentials in the above link.He says tejas is our platform ,and it can be upgraded as we wish and it meets the performance objectives set for it.
you will see the test pilot suneet krishna's credentials in the above link.He says tejas is our platform ,and it can be upgraded as we wish and it meets the performance objectives set for it.
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tkstales.wordpress.com/2012/05/11/the-tejas-debate-continues/
that is why we are hearing constant criticism from IAF top brass on tejas as opposed to the effusive praise by test pilots.Is the IAF doing it today?This is what we should concentrate.Because without it's own design expertise of some degree the IAF will be unable to understand the competence of ADA or it wont be able to make any useful suggestion to ADA.SO the friction continues. In AMCA it has already started the gap in communication is now leading to third model with in a span of 5 years.then how will deadlines be met?
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Initial proposals for LCA were prepared by the HAL Design Bureau. In the early eighties Dr Arunachalam appeared on the scene as the SA to RM. He decided to use this opportunity to upgrade the capabilities of the entire aviation industry and jump into 4th generation technologies. To him, it was clearly a DRDO project with a focus on breaking new frontiers; a laudable aim, but clearly at a variance with the air force's project goals.
- It must be understood that the air force had no quarrels with the ambitious goals of the DRDO project. It was however unable to reconcile its own re-equipment needs with the inevitable trajectory of the very ambitious DRDO goals. A compromise had to be reached.
- I do not know if there is a written document recording the compromised understanding for the situation. However, it appears that it was agreed that
Air Force funds will not be used for the development project as the AF will need its allotted money for import of weapons. Air Force will however pledge funds for acquisition of the proposed aircraft when the project reaches the stage of manufacture.
Air Force will provide necessary manpower for flight testing and other requirements as requested by the DRDO
DRDO will be fully in charge of the project.
-To assert its full control over the project, the DRDO created a new design authority entity as the ADA and cut off the HAL design bureau from the loop. A little later, a National Flight Test Centre was created and the ASTE/Flight Test group of the HAL were excluded. These actions generated some interpersonal irritations.
-Dr Velluri became the head of ADA. He wanted some one younger than Dr Raj Mahindra to head the design effort. Dr RM departed. Dr Velluri too did not last very long. He resigned. Dr KH became the head of design. The post of DGADA that Dr V vacated remained unfilled and was held by the SA to RM as an additional charge.
-To set the ball rolling, the AirHQ issued an ASR in 1985. By now the Air Force was reconciled to the Idea that the LCA will primarily be an R&D project under the DRDO. Therefore, the ASR reflected all the desires expressed by the scientific community; an unstable platform controlled by FBW technique, an airframe largely built of composites, a glass cockpit, a multi mode radar, an indigenous engine with FADEC, indigenous ECM/ECCM/electronics/weapons/missiles – the works. The ultimate product had to be an aircraft that could be used by the Air Force. Therefore the ASR projected an aircraft that would do everything that a MiG 21 could do, albeit do it a little better.
Apprehensions about the FBW were high. The air force preferred a more conservative approach of a hybrid system with French collaboration wile the DRDO opted for a more daring quad digital path with American help. The French entities walked out of the collaborative arrangements. They had been enthusiastic supporter of the LCA till then.
-In the meanwhile, many of the subsidiary developments for the LCA project were becoming reality. Thus, when the Air Force started importing the Su 30 MK from Russia in 1996, it negotiated for the incorporation of all DRDO developed stuff available at that point of time (along with some French and Israeli stuff) into it. The very fruitful MKI concept was born.
- It must be understood that the air force had no quarrels with the ambitious goals of the DRDO project. It was however unable to reconcile its own re-equipment needs with the inevitable trajectory of the very ambitious DRDO goals. A compromise had to be reached.
- I do not know if there is a written document recording the compromised understanding for the situation. However, it appears that it was agreed that
Air Force funds will not be used for the development project as the AF will need its allotted money for import of weapons. Air Force will however pledge funds for acquisition of the proposed aircraft when the project reaches the stage of manufacture.
Air Force will provide necessary manpower for flight testing and other requirements as requested by the DRDO
DRDO will be fully in charge of the project.
-To assert its full control over the project, the DRDO created a new design authority entity as the ADA and cut off the HAL design bureau from the loop. A little later, a National Flight Test Centre was created and the ASTE/Flight Test group of the HAL were excluded. These actions generated some interpersonal irritations.
-Dr Velluri became the head of ADA. He wanted some one younger than Dr Raj Mahindra to head the design effort. Dr RM departed. Dr Velluri too did not last very long. He resigned. Dr KH became the head of design. The post of DGADA that Dr V vacated remained unfilled and was held by the SA to RM as an additional charge.
-To set the ball rolling, the AirHQ issued an ASR in 1985. By now the Air Force was reconciled to the Idea that the LCA will primarily be an R&D project under the DRDO. Therefore, the ASR reflected all the desires expressed by the scientific community; an unstable platform controlled by FBW technique, an airframe largely built of composites, a glass cockpit, a multi mode radar, an indigenous engine with FADEC, indigenous ECM/ECCM/electronics/weapons/missiles – the works. The ultimate product had to be an aircraft that could be used by the Air Force. Therefore the ASR projected an aircraft that would do everything that a MiG 21 could do, albeit do it a little better.
Apprehensions about the FBW were high. The air force preferred a more conservative approach of a hybrid system with French collaboration wile the DRDO opted for a more daring quad digital path with American help. The French entities walked out of the collaborative arrangements. They had been enthusiastic supporter of the LCA till then.
-In the meanwhile, many of the subsidiary developments for the LCA project were becoming reality. Thus, when the Air Force started importing the Su 30 MK from Russia in 1996, it negotiated for the incorporation of all DRDO developed stuff available at that point of time (along with some French and Israeli stuff) into it. The very fruitful MKI concept was born.
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The design and development of the flight control laws for LCA was started in early 1993 with the formation of the National Control Law Team consisting of engineers and scientists drawn from five national aeronautical research and development institutions. The control laws being developed by this team are independently verified and validated by an IVand V team and the design process, specifications, data and results are also audited by specialists from British Aerospace UK. The maiden flight of the LCA TD-1 aircraft took place on January 4, 2001 and there were 11 more flights thereafter.
The successful completion of the first block of 12 flights with fixed gain control laws (designed and developed by the National Control Law team led by NAL) have bolstered the confidence in the aircraft's overall performance and its control law in particular. The performance of the control laws was found to be very satisfactory with the test pilots rating the aircraft as having Level 1 handling qualities in all tasks performed during these flights. The good match in the responses between flight and simulation has the given the designers adequate confidence to expand the flight envelope in the subsequent flight tests to be carried out shortly.
The successful completion of the first block of 12 flights with fixed gain control laws (designed and developed by the National Control Law team led by NAL) have bolstered the confidence in the aircraft's overall performance and its control law in particular. The performance of the control laws was found to be very satisfactory with the test pilots rating the aircraft as having Level 1 handling qualities in all tasks performed during these flights. The good match in the responses between flight and simulation has the given the designers adequate confidence to expand the flight envelope in the subsequent flight tests to be carried out shortly.
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You ask for 4th gen so i told you on 4th gen fighter..
There are category of fighters, Light, medium and Heavy...
Each of them have there own task that is how a air-force work, You cannot compare heavy with light both have different task and work differently..
Presently Mig-29, Mir-2000, Mig-21bison other fighters in Light / Medium category radar ranges below or same as LCA radar range..
There are category of fighters, Light, medium and Heavy...
Each of them have there own task that is how a air-force work, You cannot compare heavy with light both have different task and work differently..
Presently Mig-29, Mir-2000, Mig-21bison other fighters in Light / Medium category radar ranges below or same as LCA radar range..
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At high-subsonic flight speeds, supersonic airflow can develop in areas where the flow accelerates around the aircraft body and wings. The speed at which this occurs varies from aircraft to aircraft, and is known as the critical Mach number. The resulting shock waves formed at these points of supersonic flow can bleed away a considerable amount of power, which is experienced by the aircraft as a sudden and very powerful form of drag, called wave drag.
To reduce the number and power of these shock waves, an aerodynamic shape should change in cross sectional area as smoothly as possible. This leads to a "perfect" aerodynamic shape known as the Sears–Haack body, roughly shaped like a cigar but pointed at both ends.
The area rule says that an airplane designed with the same cross-sectional area distribution in the longitudinal direction as the Sears-Haack body generates the same wave drag as this body, largely independent of the actual shape.
As a result, aircraft have to be carefully arranged so that large volumes like wings are positioned at the widest area of the equivalent Sears-Haack body, and that the cockpit, tailplane, intakes and other "bumps" are spread out along the fuselage and/or that the rest of the fuselage along these "bumps" is correspondingly thinned.
The area rule also holds true at speeds higher than the speed of sound, but in this case the body arrangement is in respect to the Mach line for the design speed. For instance, at Mach 1.3 the angle of the Mach cone formed off the body of the aircraft will be at about μ = arcsin(1/M) = 50.3° (μ is the angle of the Mach cone, or simply Mach angle). In this case the "perfect shape" is biased rearward, which is why aircraft designed for high speed cruise tend to be arranged with the wings at the rear.] A classic example of such a design is Concorde.
Wallace D. Hayes, a pioneer of supersonic flight, developed the supersonic area rule in publications beginning in 1947 with his Ph.D. thesis at the California Institute of Technology
Richard T. Whitcomb, after whom the rule is named, independently discovered this rule in 1952, while working at the NACA. While using the new Eight-Foot High-Speed Tunnel, a wind tunnel with performance up to Mach 0.95 at NACA's Langley Research Center, he was surprised by the increase in drag due to shock wave formation.
Whitcomb realized that, for analytical purposes, an airplane could be reduced to a streamlined body of revolution, elongated as much as possible to mitigate abrupt discontinuities and, hence, equally abrupt drag rise.[6] The shocks could be seen using Schlieren photography, but the reason they were being created at speeds far below the speed of sound, sometimes as low as Mach 0.70, remained a mystery.
In late 1951, the lab hosted a talk by Adolf Busemann, a famous German aerodynamicist who had moved to Langley after World War II. He talked about the difference in the behavior of airflow at speeds approaching supersonic, where it no longer behaved as an incompressible fluid. Whereas engineers were used to thinking of air flowing smoothly around the body of the aircraft, at high speeds it simply did not have time to "get out of the way", and instead started to flow as if it were rigid pipes of flow, a concept Busemann referred to as "streampipes", as opposed to streamlines, and jokingly suggested that engineers had to consider themselves "pipefitters".
Several days later Whitcomb had a "Eureka" moment. The reason for the high drag was that the "pipes" of air were interfering with each other in three dimensions. One could not simply consider the air flowing over a 2D cross-section of the aircraft as others could in the past; now they also had to consider the air to the "sides" of the aircraft which would also interact with these streampipes.
Whitcomb realized that the Sears-Haack shaping had to apply to the aircraft as a whole, rather than just to the fuselage. That meant that the extra cross-sectional area of the wings and tail had to be accounted for in the overall shaping, and that the fuselage should actually be narrowed where the wing meets the fuselage meet to more closely match the ideal.
Applications
If you look at the under side of LCA you can actually notice that fuselage of LCA TEJAS follows this rule.The fuselage expands smoothly from the nose cone and from a point near the wing root it starts to narrow down to the tail.
http://www.drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf
What CEMILAC report by S.K.JEBAKUMAR states is that there is a sudden increase in cross section from x=5000 mm to x=6000 mm.It says this increase in cross section should be more smoother for further wave reduction.
This sudden incaaese may be due to the strengthening of the wing at the roots to increase the external stores capacity of LCA TEJAS.
So if we add a nose cone plug and extend the fuselage by 1 meter the shape confirmation according to WHITCOMB's area rule will be much smoother like the classic coke bottle shape.It will further reduce some drag.It will also result in the increase in internal volume for fuel and more space for avionics so it would be overall more beneficial to TEJAS.
SO area rule is followed in the design of LCA. But due to the strengthening of wing roots there was sudden raise in cross sectional are at x=5000mm to x=6000 mm.This raise is in conformity with the WHIT COMB's rule which dictates that the cross sectional are raise should continue till the pointin fuselage where the wing meets the fuselage.But instead of being gradual it is sudden raise in cross sectional are at x=5000mm to x=6000 mm that needs to be addressed.
During the planning days of LCA ,it was meant to be a mig replacement weighing 5.5 tons carrying mig like loads of 2 tons,but providing performance better than mirage modeled roughly in the flying charecteristics of delta FCS mirage.It was achieved.Then with the advent of close to 200 kg modern BVRs ,naturally the weapons load is increased to 4 tons,because these BVRs weigh close to 150 kg each.
For that wing and the meeting point of wing with fuselage needed to be strenghtened resulting in the sudden raise in cross section instead of gradual raise as it is too late to alter the entire fuselage length at an advanced stage of the program as it would delay it further.SO once all the important testing parameters are achieved this change in nose cone plug and fuselage cross section smoothening can be easily validated later as it will only increase the aerodynamics not reduce it in anyway.
SINCE ACCORDING TO THE INTERVIE WITH KOTA HARINARAYANA IN ADA WEBSITE,
THE TEJAS FCS WAS TESTED ON AN F-16 FIRST AND THEN ONLY IT WAS IMPLEMENTED ON LCA TEJAS.
So changing FCS to accomadate this CEMILAC recommendations wont be a problem.
So it seems that FCS is modular platform independant software implementation that can be suitably adapted to F-16 and LCA.
So there may not be much problem on that count.
To reduce the number and power of these shock waves, an aerodynamic shape should change in cross sectional area as smoothly as possible. This leads to a "perfect" aerodynamic shape known as the Sears–Haack body, roughly shaped like a cigar but pointed at both ends.
The area rule says that an airplane designed with the same cross-sectional area distribution in the longitudinal direction as the Sears-Haack body generates the same wave drag as this body, largely independent of the actual shape.
As a result, aircraft have to be carefully arranged so that large volumes like wings are positioned at the widest area of the equivalent Sears-Haack body, and that the cockpit, tailplane, intakes and other "bumps" are spread out along the fuselage and/or that the rest of the fuselage along these "bumps" is correspondingly thinned.
The area rule also holds true at speeds higher than the speed of sound, but in this case the body arrangement is in respect to the Mach line for the design speed. For instance, at Mach 1.3 the angle of the Mach cone formed off the body of the aircraft will be at about μ = arcsin(1/M) = 50.3° (μ is the angle of the Mach cone, or simply Mach angle). In this case the "perfect shape" is biased rearward, which is why aircraft designed for high speed cruise tend to be arranged with the wings at the rear.] A classic example of such a design is Concorde.
Wallace D. Hayes, a pioneer of supersonic flight, developed the supersonic area rule in publications beginning in 1947 with his Ph.D. thesis at the California Institute of Technology
Richard T. Whitcomb, after whom the rule is named, independently discovered this rule in 1952, while working at the NACA. While using the new Eight-Foot High-Speed Tunnel, a wind tunnel with performance up to Mach 0.95 at NACA's Langley Research Center, he was surprised by the increase in drag due to shock wave formation.
Whitcomb realized that, for analytical purposes, an airplane could be reduced to a streamlined body of revolution, elongated as much as possible to mitigate abrupt discontinuities and, hence, equally abrupt drag rise.[6] The shocks could be seen using Schlieren photography, but the reason they were being created at speeds far below the speed of sound, sometimes as low as Mach 0.70, remained a mystery.
In late 1951, the lab hosted a talk by Adolf Busemann, a famous German aerodynamicist who had moved to Langley after World War II. He talked about the difference in the behavior of airflow at speeds approaching supersonic, where it no longer behaved as an incompressible fluid. Whereas engineers were used to thinking of air flowing smoothly around the body of the aircraft, at high speeds it simply did not have time to "get out of the way", and instead started to flow as if it were rigid pipes of flow, a concept Busemann referred to as "streampipes", as opposed to streamlines, and jokingly suggested that engineers had to consider themselves "pipefitters".
Several days later Whitcomb had a "Eureka" moment. The reason for the high drag was that the "pipes" of air were interfering with each other in three dimensions. One could not simply consider the air flowing over a 2D cross-section of the aircraft as others could in the past; now they also had to consider the air to the "sides" of the aircraft which would also interact with these streampipes.
Whitcomb realized that the Sears-Haack shaping had to apply to the aircraft as a whole, rather than just to the fuselage. That meant that the extra cross-sectional area of the wings and tail had to be accounted for in the overall shaping, and that the fuselage should actually be narrowed where the wing meets the fuselage meet to more closely match the ideal.
Applications
If you look at the under side of LCA you can actually notice that fuselage of LCA TEJAS follows this rule.The fuselage expands smoothly from the nose cone and from a point near the wing root it starts to narrow down to the tail.
http://www.drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf
What CEMILAC report by S.K.JEBAKUMAR states is that there is a sudden increase in cross section from x=5000 mm to x=6000 mm.It says this increase in cross section should be more smoother for further wave reduction.
This sudden incaaese may be due to the strengthening of the wing at the roots to increase the external stores capacity of LCA TEJAS.
So if we add a nose cone plug and extend the fuselage by 1 meter the shape confirmation according to WHITCOMB's area rule will be much smoother like the classic coke bottle shape.It will further reduce some drag.It will also result in the increase in internal volume for fuel and more space for avionics so it would be overall more beneficial to TEJAS.
SO area rule is followed in the design of LCA. But due to the strengthening of wing roots there was sudden raise in cross sectional are at x=5000mm to x=6000 mm.This raise is in conformity with the WHIT COMB's rule which dictates that the cross sectional are raise should continue till the pointin fuselage where the wing meets the fuselage.But instead of being gradual it is sudden raise in cross sectional are at x=5000mm to x=6000 mm that needs to be addressed.
During the planning days of LCA ,it was meant to be a mig replacement weighing 5.5 tons carrying mig like loads of 2 tons,but providing performance better than mirage modeled roughly in the flying charecteristics of delta FCS mirage.It was achieved.Then with the advent of close to 200 kg modern BVRs ,naturally the weapons load is increased to 4 tons,because these BVRs weigh close to 150 kg each.
For that wing and the meeting point of wing with fuselage needed to be strenghtened resulting in the sudden raise in cross section instead of gradual raise as it is too late to alter the entire fuselage length at an advanced stage of the program as it would delay it further.SO once all the important testing parameters are achieved this change in nose cone plug and fuselage cross section smoothening can be easily validated later as it will only increase the aerodynamics not reduce it in anyway.
SINCE ACCORDING TO THE INTERVIE WITH KOTA HARINARAYANA IN ADA WEBSITE,
THE TEJAS FCS WAS TESTED ON AN F-16 FIRST AND THEN ONLY IT WAS IMPLEMENTED ON LCA TEJAS.
So changing FCS to accomadate this CEMILAC recommendations wont be a problem.
So it seems that FCS is modular platform independant software implementation that can be suitably adapted to F-16 and LCA.
So there may not be much problem on that count.
Last edited:
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Tarmak007 -- A bold blog on Indian defence: CEMILAC boss bats for an integrated national project for aero-engines
you can read the cemilac chief's interview here.
you can read the cemilac chief's interview here.
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You really cannot comprehend what is being written can you, go ahead and re read my post. It specifically mentions that every FCS is meant to operate in a finite limit. That is more than self explanatory.
The Pylons of any aircraft are situated close to the center of gravity and the flight control system is designed to manage those variations. That is what I implied by using finite limit. Its not my problem if you aren't familiar with how control systems are designed, verified and tested.
Did you know that fuel is compartmentalized and dynamically managed in any aircraft to avoid change in CoG with increasing or depleting fuel levels, you wouldn't be posing such a nincompoop question had you been aware of the fact.
By shifting the cockpit, radar, LRU's obog, life support measures, front landing gear forward would be shifting almost one and half tons of weight by half to one meter ahead. Furthermore adding half to one meter of length to the airframe would construe to addition of 500 kilos to a ton of weight in additional fuel LRUs and structure. That sir, is not a minor change for a six and half ton fighterBTW did you know that the Tejas is far too unstable as the FCS is already struggling to achieve design parameters with the current CoG because the components in Tejas are too heavy for what the FCS was designed for (check this link, its just from the last couple of months
Didn't you check the links I gave you ? fuselage extension is being done on mk2. On the other hand you have been claiming that fuselage extension has been incorporated in Mk1 itself with no proof of such (you didn't gave proofs for Cheetah and Kfir having fuselage lengthening via mid life upgrades either
Rant on/
Respected Mods,
The thread is being derailed by one poster who refuses to give proof for the claims he is making. None, zilch, Nada and shall not back down from making disingenuous posts. This is highly infuriating to posters who actually do. Please take notice before other posters quit posting in this thread and it gets filled with pages after pages of unsubstantiated claims, and nationalistic tripe.
Regards,
Twinblade.
Rant off/
you have posted stuff about CEMILAC report in the following thread.
FA-50, really comparable to Tejas? [Archive] - Key Publishing Ltd Aviation Forums
where
boom
countered you with the remark
then sign says
YOUR REPLY IS
SPITFIRE SAYS
FOR THAT mad rat SAYS
THEN YOU HAVENT MADE ANY REPLY.
now,
SINCE ACCORDING TO THE INTERVIE WITH KOTA HARINARAYANA IN ADA WEBSITE,
THE TEJAS FCS WAS TESTED ON AN F-16 FIRST AND THEN ONLY IT WAS IMPLEMENTED ON LCA TEJAS.
according to him the F-16 TEST PILOT SAID THAT THE "F-16 HANDLES BETTER AERODYNAMICALLY WITH THE TEJAS FCS,IT HANDLES MUCH BETTER.since then FCS was exported to( boeing or?) airbus by ADA.
So changing FCS to accomadate this CEMILAC recommendations wont be a problem.
So it seems that FCS is modular platform independant software implementation that can be suitably adapted to F-16 and LCA.
There seems to be provision for redundancies and modularity and adaptability for change in FCS as per the new requirements of platforms.
Since sukhoi is about to be paired with brahmos does that also means it's FCS is perfectly capable of meeting that requirement?
So there may not be much problem on that count.
PLEASE REPLY .
THANKS.
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Bachchu Yadav
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Good write up !
But i have few questions..
1. It is implied that all we need is to have a large wing area to build a fighter aircraft.But what about air drag ?
More wing area-> Larger air drag->More powerful engine -> More weight of an aircraft
2. In aircraft designing, there is always trade off between maneuverability and speed . LCA speed is 1.8 Mach, we can infer that speed in scarified for sake of speed.(Since Mig 21 speed is >2 Mach whom it want to replace)
3. Now Kaveri engine is producing (52/81 KN) of thrust which is comparable to F404 (53/78KN). People says LCA is underpowered, but why they started from underpowered engine. Either LCA designer don't know about LCA design or they don't have choice other than F404 ??
4. Those who beats drum about superior design of LCA aircraft must know one of the main features of LCA mk 2 to improve airframe(What!!).
5. Given the role of LCA tejas of being an interceptor in IAF , Main feature of Interceptor is to have SPEED, Tejas mk 1 has even lesser speed than Mig 21. God knows how it perform it's role as interceptor .
I too want this LCA tejas to be one of the best 4.5 gen fighter. Hell ! I become too sad whenever I see LCA.
We read talks about LCA's composite material, fly by wire ... but when it comes to performance , it sucks . Do anybody tell me it's CLIMB RATE ?? some says it is just more than 3rd Gen fighters like MIG 21.
To my mind the real reason behind failure of Kaveri was bellow one ...
Top defence scientist netted in Jayamahal massage parlour raid, News - Cover Story - Bangalore Mirror,Bangalore Mirror
People at GTRE (Barring few) has just played with not only people's money but also their emotions. I think it is the time people should held accountable whatever good or bad , they have done.
But in the end , This is India .. "sab chalata hai"
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p2prada
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I asked the same question, they still have no answer.
If I point out that both Mirage-2000 and Mirage-III have very similar wing loading as the LCA, they won't have an answer to why both aircraft have a sustained turn rate lesser than F-16. Heck the "low wing loading" Mirage III has STR(15deg/s at Mach 0.6, sea level) and ITR(~20 deg/sec) that is very less compared to high wing loading F-16(450Kg/m2).
Wingloading for Mirage III is 298Kg/m2, Mirage-2000 is 283Kg/m2, LCA is 260Kg/m2, if you consider full internal fuel and 1000Kg payload.
No answer if you tell them 330Kg/m2+ aircraft like Rafale, EF and MKI have superior STR and ITR to all 3 aircraft above.
It's lie these guys were taught passenger aircraft physics during their school and college days.
They have never heard about lifting body designs either. They would not even have heard of a F-15 making it back to base with one wing torn off.
Anyway the reason why Mig-21, Mirage-III and MIrage-2000 have higher speeds is because of inlet cones on all 3 aircraft. These shock the air to subsonic speed before entering the compressor. Comparatively, LCA's inlets are very simple in design. So, speeds above Mach 1.8 are theoretically impossible with conventional engines.
Bachchu Yadav
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1. Wing loading is an important determinant of speed but not only determinant of speed.(glide angle etc)
2. All aircraft having same wingloading may not have same speed. WING SHAPE is also imp factor.
Now let me try to answer you ..
1. F 16 has better performance despite higher wingloading than Mirage ..
. due the engine thrust ... f 16 have colossal 127KN thrust but mirage 2000 have only 95KN.
2. Rafale EF and MKI all are double engine machine ...
...having nearly double engine thurst than LCA, that's why despite high wingloading than LCA .. they are more maneuverable ..
Near to me , aircraft designing is all about trade off.:thumb:
My question is ... why the hell LCA designers started with underpowered engine ?
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acetophenol
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whats the endurance time of LCA?
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100 space missions,super computers nuclear bombs,nuclear subs ICBMs and fast breeder reactors and submarine launched cruise missile have escaped your eyes it seems. There can be no reply to these type of queries.
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SO you need not worrry much as a project LCA is on track
Bachchu Yadav
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Are you spokesperson for ADA or HAL ? Because you are behaving so....
Whom are you fooling ? LCA mk2 will be powered by GE 414 which have maximum thrust 98KN, but F 16 is powered by P&W F110 which have >120KN.
So the same 120KN is not available to LCAmk2 . Don't try to fool us !
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