ADA Tejas (LCA) News and Discussions

[ersakthivel]

@ersakthivel

Isn't this a fanboy compilation (even though at Business Insider) ? I had seen it last week.

However, I concede that relaxed static stability is the latest buzzword aviators seem to be discussing (keypublishing & other forums).

But, there would never be any last word on fighter design.

It is not the latest it started from Mirage-2000 in 1980s itself,

From those days all new fighters that were designed designed in the western world till now has this relaxed static stability.

 

[ersakthivel]

I wud call it relaxed static shit. The pitch up rate is not the only parameter for ITR, roll rate is coupled with it. LCA has lower roll rate than even GNAT and Hunter. So if you combine the time taken to roll for a bank angle and pitch up rate, you will find that this relaxed static shit sold by Americans is of no use. Do you know that these so called RSS ac have pitch up rate sensors to limit the rate? RATE is what I stated. Hunter FYI had a roll rate of 720 degrees/sec.

Is this instantaneous roll rate or sustained roll rate?

How many Gs can the hunters and GNAT can pull in sustained Gs per second calculation? this is also a crucial factor in fighter capability,

Also you can post the range fuel carrying capacity sustained turn rate per second and Instantaneous turn rate per second of the hunters and GNATs for a fair comparison

 

[TrueSpirit]

It is not the latest it started from Mirage-2000 in 1980s itself,

From those days all new fighters that were designed designed in the western world till now has this relaxed static stability.

Yes, that's what I found out but not sure what is the reason for interest in this widely popular concept ? As Decklander stated above, there is much more to it than just pitch up rate.

 

[TrueSpirit]

Do you know that these so called RSS ac have pitch up rate sensors to limit the rate? RATE is what I stated.

Sir, why do they want to limit the rate ? Is it really desirable having these sensors ?

 

[Decklander]

Sir, why do they want to limit the rate ? Is it really desirable having these sensors ?

It is done so that pilots do not suffer from G-LOC due to very high rate of onset of G-forces.
Infact not just F-15 but even MIG-29s are non FBW stable designs. Only recent models of MIG-29 have FBW.

 

[Decklander]

Yes, that's what I found out but not sure what is the reason for interest in this widely popular concept ? As Decklander stated above, there is much more to it than just pitch up rate.

Even ac designers suffer from goat mentality. remember swing-wings, everyone did create such fighters and now no one is creating them. RSS is another such bubble. It too will live out its life soon.

 

[TrueSpirit]

Even ac designers suffer from goat mentality. remember swing-wings, everyone did create such fighters and now no one is creating them. RSS is another such bubble. It too will live out its life soon.

Yes Sir, I have just heard that Mig27 has an inherently unstable design. Is swing-wing to be blamed ?

 

[TrueSpirit]

It is done so that pilots do not suffer from G-LOC due to very high rate of onset of G-forces.
Infact not just F-15 but even MIG-29s are non FBW stable designs. Only recent models of MIG-29 have FBW.

So, is it that fast Air-superiority fighters can do without FBW but FBW is more relevant for multi-role AC's ?

 

[ersakthivel]

I wud call it relaxed static shit. The pitch up rate is not the only parameter for ITR, roll rate is coupled with it. LCA has lower roll rate than even GNAT and Hunter. So if you combine the time taken to roll for a bank angle and pitch up rate, you will find that this relaxed static shit sold by Americans is of no use. Do you know that these so called RSS ac have pitch up rate sensors to limit the rate? RATE is what I stated. Hunter FYI had a roll rate of 720 degrees/sec.

Even ac designers suffer from goat mentality. remember swing-wings, everyone did create such fighters and now no one is creating them. RSS is another such bubble. It too will live out its life soon.

What roll rates you are referring to instantaneous roll rate or sustained?

1.When you say instantaneous roll-rate, that means the roll-rate it reaches the instant the control-column is slammed all the way to one side right?

2.Once the drag of the deployed control surfaces takes effect that the airplane slows somewhat, reducing its performance. Similar to intantaneous vs. sustained G capability or turn rates. So sustained roll rate cannot be 720 deg per second for hunters and GNATS.

Even the F-16 and grippen and Typhoon have all sustained roll rates in the range of 220 to 270, at the same time they have far higher instantaneous roll rates, but that does not count as sustained roll rate is what counts , because that is the fig we can really check in air show performance for any close combat relevance.

So it is hard to believe the hunter and GNATS had 720 deg per second sustained roll rates.

Sustained roll rate is what counts in determining the agility of the plane in it's full envelope.

We can read some stuff here,

http://www.airliners.net/aviation-forums/military/read.main/97791/

 

[Decklander]

What roll rates you are referring to instantaneous roll rate or sustained?

1.When you say instantaneous roll-rate, that means the roll-rate it reaches the instant the control-column is slammed all the way to one side right?

2.Once the drag of the deployed control surfaces takes effect that the airplane slows somewhat, reducing its performance. Similar to intantaneous vs. sustained G capability or turn rates. So sustained roll rate cannot be 720 deg per second for hunters and GNATS.

Even the F-16 and grippen and Typhoon have all sustained roll rates in the range of 220 to 270,

So it is hard to believe the hunter and GNATS had 720 deg per second sustained roll rates.

Sustained roll rate is what counts in determining the agility of the plane in it's full envelope.

We have had a long discussion about this in the past. I had stated at that time what I needed to say. I will not join a debate about it again with you. But yes, GNAT and Hunter had one the best roll rates. You can't have an Instant roll rate and Sustained roll rate. Roll rate is always the max rate which can be generated by an ac. however ITR & STR vary for each ac. There are ac which have limitation of roll rates and also max number of rolls they can do continuously. even for best fighters it is generally restricted to two rolls.

 

[Decklander]

Sir, why do they want to limit the rate ? Is it really desirable having these sensors ?

Found this on wiki regarding Mig-29.
The MiG-29 has hydraulic controls and a SAU-451 three-axis autopilot but, unlike the Su-27, no fly-by-wire control system. Nonetheless, it is very agile, with excellent instantaneous and sustained turn performance, high-alpha capability, and a general resistance to spins. The airframe consists primarily of aluminium with some composite materials, and is stressed for up to 9-g (88 m/s²) maneuvers. The controls have "soft" limiters to prevent the pilot from exceeding g and alpha limits, the limiters can be disabled manually.

 

[ersakthivel]

We have had a long discussion about this in the past. I had stated at that time what I needed to say. I will not join a debate about it again with you. But yes, GNAT and Hunter had one the best roll rates. You can't have an Instant roll rate and Sustained roll rate. Roll rate is always the max rate which can be generated by an ac. however ITR & STR vary for each ac. There are ac which have limitation of roll rates and also max number of rolls they can do continuously. even for best fighters it is generally restricted to two rolls.

you may not want to discuss about it and that is perfectly acceptable to me.

it ran into pages in the ADA Tejas mk-2 thread here, I too have no stamina to repeat it here again.

But don't consistently run down RSS as a tech bells and whistle that is not needed by IAF

and ADA pulled a con on IAF by including it which resulted in LCA's delay,

Simply anything other than the low wing loading RSS deltas are not accepted as modern fighters, Mig-29 and , F-15 belong to the 1980s. They were mighty then. But no one knows they can lord over the skies dominated by RSS deltas like typhoons and RAFALEs in a purely aerodynamic way of speaking,

Not going to be because TYPHOON and RAFALE have both better ITR and STR than the MIG-29 and F-15, So that has got some thing to do with RSS as well, however smaller it's contribution may be,

Old days every one had simple straight very high wing loading wings shape , So there was no need for RSS fly by wire tech.

But today practically every fighter maker is veering towards large wing area low wing loading fighters (all some form of deltas),

Without RSS and fly by wire these fighters cannot even be optimally used .

Analysis of PAK-FA prototype airframe aerodynamic features shows a design which is superior to all Western equivalents, providing 'extreme agility', superior to that of the Su-35S, through much of the flight envelope. This is accomplished by the combined use of 3D thrust vector control of the engine nozzles, all moving tail surfaces, and refined aerodynamic design with relaxed directional static stability and careful mass distribution to control inertial effects. The PAK-FA is fitted with unusually robust high sink rate undercarriage, intended for STOL operations.

Assessing the Sukhoi PAK-FA / Sukhoi/KnAAPO T-50/I-21/Article 701 PAK-FA Перспективный Авиационный Комплекс Фронтовой Авиации

The above is a passage from Dr Carlo Kopp,

So the Russians are now also designing low wing loading(large wing area , commonly called deltas) RSS fly by wire PAKFA as well,

of course the MIG-29 is very agile because it has a TWR equivalent to that of RAFALE and TYPHOONs of today,

See the comparison,

Mig-29k :
Speed: Mach 2+ (2,200 km/h, 1,370 mph) / At low altitude: Mach 1.2 (1,400 km/h, 870 mph).
Ferry range: 2,100 km (1,240 mi) / 3,000 km (1,860 mi) with 3 drop tanks
Combat radius : 850km
Service ceiling: 17,500 m (57,400 ft)
Rate of climb: initial 330 m/s, average 109 m/s 0-6000 m (65,000 ft/min)
Wing loading: 442 kg/m² (90.5 lb/ft²)
Thrust/weight: 0.97

Rafale :
Maximum speed:High altitude: Mach 1.8+ (2,130+ km/h, 1,050+ knots)Low altitude: Mach 1.1+ (1,390 km/h, 750 knots)
Range: 3,700+ km (2,000+ nmi)
Combat radius: 1,852+ km (1,000+ nmi) on penetration mission
Service ceiling: 16,800 m (55,000 ft)
Rate of climb: 304.8+ m/s (60,000+ ft/min)
Wing loading: 306 kg/m² (62.8 lb/ft²)
Thrust/weight: 0.988 (100% fuel, 2 EM A2A missile, 2 IR A2A missile) version M


see the range, combat radius figures , rate of climb, weaponload figures,

both are twin engined fighters , with almost the same TWR,

But RAFALE while carrying higher weapon load and having greater range still outperforms the MIG-29 in ITR and STR as well,

if it is not enabled by Relaxed static stability airframe design of RAFALE, give the reason why?

No use saying the RAFALE has high percentage of composites,

Both have almost the same engine TWR as well, (I am not very sure about plain engine TWR, but since RAFALE too uses an older version engine I hope not much difference there.)

Because both have the same TWR for air force version, but still the air force version of RAFALE will out perform the Mig-29 in all critical parameter.

But the minus point is even while having twin engines the high empty weight of MIG-29 makes it very much a single engined fighter when it comes to range,

Why?

In the quest to beat the RSS enabled F-16 russians built MIG-29s to be a very high TWR fighter with two engines for power and very low fuel fraction , sacrificing the range,

The TYPHOON and RAFALE have much better fuel fraction as well ,

If the makers of TYPHOON and RAFALE chose the same path and made a very low fuel fraction RSS fighter with same range and TWR of MIG-29, that plane would easily have beaten MIG-29 in combat.

 

[Decklander]

Never ever look at a weapon system thru the prism of just one of its qualities.
The advent of all aspect missiles and helmet mounted sighting system have completely changed the air battles. Even the USAF found it hard way when they squared up against MIG-29s in WVR combat in Germany. Those RSS, FBW ac were of no use against MIG-29s and its helmet mounted sighting system. Nearly every RSS ac bcoms stable design at about 0.9 mach. The speed of air combat has progressed from 100kmph from WW1 to 300 KMPH in WW2 begining to 500KMPH by end of WW2 to 700 KMPH in vietnam war. Now we live in an era of AWACs and BVRAAMs plus IIR homing BVRAAMs. The kinematic energy of an ac has direct effect on the range of the missile also. So a higher speed is most desirable during combat wherein these RSS ac are actually stable.
The time of combat has also changed from 10-15 mins from WW1 to 5-7 mins in WW2 to 2-3 mins in Vietnam to now just 1-1.5 mins. So any ac which drops its speed during combat will lose out and very likely to be shot out as it will be committed to defend and avoid rather than attack and strike.

 

[ersakthivel]

Never ever look at a weapon system thru the prism of just one of its qualities.
The advent of all aspect missiles and helmet mounted sighting system have completely changed the air battles. Even the USAF found it hard way when they squared up against MIG-29s in WVR combat in Germany. Those RSS, FBW ac were of no use against MIG-29s and its helmet mounted sighting system. Nearly every RSS ac bcoms stable design at about 0.9 mach. The speed of air combat has progressed from 100kmph from WW1 to 300 KMPH in WW2 begining to 500KMPH by end of WW2 to 700 KMPH in vietnam war. Now we live in an era of AWACs and BVRAAMs plus IIR homing BVRAAMs. The kinematic energy of an ac has direct effect on the range of the missile also. So a higher speed is most desirable during combat wherein these RSS ac are actually stable.
The time of combat has also changed from 10-15 mins from WW1 to 5-7 mins in WW2 to 2-3 mins in Vietnam to now just 1-1.5 mins. So any ac which drops its speed during combat will lose out and very likely to be shot out as it will be committed to defend and avoid rather than attack and strike.

All close air combat is conducted at trans sonic range , just below the mach 1, where most of the dog fights occur, and that is where the RSS deltas excell.

because fighters won't be that maneuverable in mach 1 plus speeds regardless of the fact whether they are RSS or not.

long range and WVR missile kill be the major component of the air to air kills in future,

but when the chips are down the fighter pilot has to win with guns , for that only RSS , fly by wire deltas give the guarantee,

Chips will be down once the first BVR is fired, You must have known ,

that if you have to avoid the BVR from enemy , you have to pull more more Gs , turn tighter , climb faster,

No fighter in the world will manage all of it's design max specs 4 ton weapon load,

as we all know most of the fancy specs of fighters are only for zero weapon load,

So to pulls of these cobras or rope tricks the pilot will jettison most of his weapon load

And lets assume that he succeeds in doing so by droping all weapon loads and employing jamming techniques,

You can say the same about the enemy fighter as well, So he too will have dropped all missiles and weapon load to evade the missile fired by you,

Then what do you think, Both pilots will go back to base happily ever after?

No they will begin the below mach 1 close combat , where these inconvenient stuffs like RSS , FCS, fly by wire will decide the winner.

A fighter has to be a bare frame fighter before it wears most of it's missiles , You can rest assured that IAf will never accept a fighter relying only on BVR and WVR missile specs,

They will always demand the ITR and STR besides the WVR , BVR specs as well,

So ADA has no choice other than to employ them if it has to produce a competent fighter for IAF.

So I too don't want to discuss this any further as there are no new points in it and since we discussed it to death in Tejas mk-2 thread.

 

[Kunal Biswas]

Designing And Testing Flight Control Laws Of Light Combat Aircraft


Published on Feb 16, 2013

Mr. Shyam Chetty, Acting Director, National Aerospace Laboratories [NAL], speaking at the Aero India 2013 Airshow Seminar.

 

[ersakthivel]

Designing And Testing Flight Control Laws Of Light Combat Aircraft


Published on Feb 16, 2013

Mr. Shyam Chetty, Acting Director, National Aerospace Laboratories [NAL], speaking at the Aero India 2013 Airshow Seminar.

This experience of development of flight control laws is as important as the end product itself,

As it provides a solid bedrock for building fly by wire flight control laws for AMCA and any other flying crafts in future,

Even with decades of experience SAAB failed in this area, and after the crash of first prototype due to failure of Fly by wire design by SAAB, they rushed to a US firm to design this crucial flight control laws , but the development of these laws by ADA without any external help(as all the computers, and software developed by ADA team with US support were seized by US after nuclear test and ADA has to do it again from scratch leading to 3 or 4 years delay i the program ) is a crucial achievement.

 

[Sridhar]

LCA-Tejas has completed 2298 Test Flights Successfully. (24-Aug-2013).

(TD1-233,TD2-305,PV1-242,PV2-222,PV3-368,LSP1-74,LSP2-281,PV5-36,LSP3-157,LSP4-93,LSP5-209,LSP7-51,NP1-4,LSP8-23)

(TD1-233,TD2-305,PV1-242,PV2-222,PV3-368,LSP1-74,LSP2-281,PV5-36,LSP3-157,LSP4-92,LSP5-209,LSP7-51,NP1-4,LSP8-21)

 

[brahmastra11]

Today I heard 1 sortie more..

LCA-Tejas has completed 2298 Test Flights Successfully. (24-Aug-2013).

(TD1-233,TD2-305,PV1-242,PV2-222,PV3-368,LSP1-74,LSP2-281,PV5-36,LSP3-157,LSP4-93,LSP5-209,LSP7-51,NP1-4,LSP8-23)

(TD1-233,TD2-305,PV1-242,PV2-222,PV3-368,LSP1-74,LSP2-281,PV5-36,LSP3-157,LSP4-92,LSP5-209,LSP7-51,NP1-4,LSP8-21)

 

[brahmastra11]

Today heard 2 more sorties.. So that brings up total to 2301 test flights successfully.

Today I heard 1 sortie more..
LCA-Tejas has completed 2298 Test Flights Successfully. (24-Aug-2013).

(TD1-233,TD2-305,PV1-242,PV2-222,PV3-368,LSP1-74,LSP2-281,PV5-36,LSP3-157,LSP4-93,LSP5-209,LSP7-51,NP1-4,LSP8-23)

(TD1-233,TD2-305,PV1-242,PV2-222,PV3-368,LSP1-74,LSP2-281,PV5-36,LSP3-157,LSP4-92,LSP5-209,LSP7-51,NP1-4,LSP8-21)
Sridhar ↑

 

[ersakthivel]

It is the very talented young persons who need to be retained to do innovative work in our laboratories. This will happen only if we create world class laboratories and offer competitive remuneration. We have about seven global class Business Schools. Top talents from these Schools should also be retained by similar means. The annual output of these institutes is not enough and we need many more top class institutes to cater to our requirements in technology and management.

http://www.bharat-rakshak.com/IAF/Today/Opinions/1134-IM-Chopra.html

Food for thought for MOD, if it wants to seriously retain valuable talent here, because I faintly remember that one DFI technocrat in particular posting that salaries for the present scientific workforce under the government was more than enough, Unfortunately the author does not think so.

The strength of HAL lies in production and overhaul. The work force is experienced and normally produces aircraft to schedule. Optimistic schedules given in HAL Project Reports are sometimes difficult to meet. On other occasions schedules are not met because there are genuine difficulties. When I was MD at Bangalore Complex, the biggest challenge was producing the tooling for Jaguar.

Tooling is a one-time activity and due to the large numbers involved subcontracting was the option to be explored. It was difficult to get subcontractors who would make tools to the close tolerances required. We managed by placing with the contractors for short periods machinist to help achieve the quality needed and quality control inspectors for maintaining the dimensions. This was done first time by HAL with success. It is worth mentioning that at the raw material stage of production even with about Rs. 2 crore amortisation of tooling on each aircraft on the 75 aircraft ordered, the price was cheaper than the imported cost. Sometimes the imported price is cheaper because of tooling cost and the high man hours taken at HAL because of the learning. The thumb rule for learning is that full learning is achieved after producing about 100 Jaguar class of aircraft.

It is also important that piece meal orders are not placed. In the past continuation order has been placed for as low as 3-5 aircraft when the production of that type of aircraft has already ended. These types of orders lead to higher cost of production. It appears defence finance thinks "payment delayed is money saved", a joke in the corridors of South Block.

But this is what IAF is doing by placing 20 plus 20 plus 80 order batches for IAF . The article writer is a retired test pilot of HAL.
He stresses the importance of high volume order to develop higher level production standards and efficiency with lower cost .
While IAF and IA follow the same principle for large import orders with foreign vendors , it does the opposite with local production

and less said the better about the IA order numbers for Arjun.

HAL is a vertically integrated company. Practically every item is made in house ranging from accessories, avionics, and engines to aircraft. It is a management's nightmare. No company in the world attempts such vertical integration. About 60-70% of a Boeing aircraft is made by subcontractors. When I tried to get engine fuel pump components for the Jaguar made by MICO, Bangalore (Bosch subsidiary), it was a non-starter because we needed manufacturing tolerance of 5 micron and MICO had experience of working with 25 Micron. I think now 20 years later it would be possible to induce private sector to set up high-tech units for building accessories etc.

it would be possible only if higher volume orders are given for Arjun or Tejas. Because you won't expect any private sector firm to invest in production line and tech for 20 plus 20 plus 80 orders spread over a decade. It is a waste of resource and time for them.

So IAF will continue to lament about the production quality at HAL and lack of private participation , without even realizing it is their actions that leads to this sorry situation. In the combat theater LCA in it's mk-2 version can do most of all what RAFALE can do because both have the sane TWR, same RSS delta design and will have almost the same ITR and STR.

And we have to see whether RAFALE can achieve all it's top specs in indian hot and humid weather conditions. Certainly it won't as experience already has shown. Su-30 MKI , Mig-29 and LCA tejas all have the same top speeds at Indian hot and humid weather conditions in skies over GOA as the official press release suggest.

With ever increasing chinese PLAF numbers having LCA mk-2 in more than 200 hundred numbers is a basic requirement and it will also stimulate a huge interest among local big private players to get into defence production leading to massive increase in quality control issues.

By givin 20 plus 20 plus 80 order nothing of this sort w9ill ever happen.

So there is nothing wring in giving 250 plus order number for Tejas mk-2

The HF-24 Marut from design to first flight was in five years, a unique achievement perhaps not even achieved in the West. This schedule became a reality because Dr. Kurt Tank was an extremely good leader. He not only led the design team but also excelled in supervising the production of the prototype as he had experience of producing aircraft in thousands annually during World War II. The design team of Indian engineers and the workers provided excellent support for the schedule achieved. It is a pity that Orpheus 12, the engine around which Marut was designed was never produced. The aircraft was contemporary and with Orpheus 12, it would have excelled in performance.

Why this engine development was not funded is a serious mystery, However recent Wiki leak revealations exposing that a son in law of the former IAF chief and princes of ruling dynasty were the chief lobyists for the tender that killed the Marut will definitely provide the motivation in ruling circles not to fund the orpheus 12 engine development.

This mysterious decision lead to destruction of HAL's design capabilities and flight of Kurt Tank led design team,

Only after seeing this sorry state of affairs the scientific elite of the country including many from ISRO, DRDO , to carve out the design team from HAL into ADA and the result today is LCA is about to enter into service .

During the United front government the decision to close the LCA program was almost taken and it was the intervention of Ratan TATA which saved the program.