Su-30: News and Discussion

SanjibGhosh · Post by **SanjibGhosh** » 22 Jul 2009 19:19

Sukhoi Su-30 crash of systems failure: Antony

http://www.samaylive.com/news/systems-f ... 40042.html

Cybaru · Post by **Cybaru** » 22 Jul 2009 19:32

from the above link
The Su-30 was inducted in 1996 and the IAF fleet currently comprises 98 aircraft. This will rise to 230 by 2015.

SanjibGhosh · Post by **SanjibGhosh** » 22 Jul 2009 20:04

this seems to be an interesting artical but can someone translate it to correct English (just brief). Could not understand what this Chines guy wanted to say ....

India plans to the Russian Su-30MKI to install the latest snow radar
http://www.translate.google.com/transla ... ry_state0=

Andrew DeCristofaro · Post by **Andrew DeCristofaro** » 22 Jul 2009 20:11

what if there is bad whether and litening pod doesn't work and mki will need 20600 RTP to drop LGBs

and even for SAR imagery at 120 km by 2060p pod would it be clear enough for differentiation of different objects.

and would the SAR image taken from 120km be clear enough for standoff PGMs to be dropped later or at the same time by other aircrafts which can use this SAR IMAGE and if one needs to drop PGM then he needs much clear picture of ground differentiating different object clearly and for this SAR image comes down to 50-60 km only

NRao · Post by **NRao** » 22 Jul 2009 20:13

AD,

Please avoid pasting the entire posting............. relevant sections should do.

Thx.

Nihat · Post by **Nihat** » 22 Jul 2009 20:24

SanjibGhosh wrote:this seems to be an interesting artical but can someone translate it to correct English (just brief). Could not understand what this Chines guy wanted to say ....

India plans to the Russian Su-30MKI to install the latest snow radar
http://www.translate.google.com/transla ... ry_state0=

I remember seeing this article before , the Chinese reporter has of his own free will added China to Russia and India as joint developers of the Brahmos.

krishnan · Post by **krishnan** » 23 Jul 2009 13:30

Defence Minister to Parliament: Prelim investigation into IAF Sukhoi-30MKI crash points to failure of the Fly-by-Wire system

-- livefist

parshuram · Post by **parshuram** » 23 Jul 2009 15:06

From ITAR TASS

July, 23rd. (ITAR-TASS). The Ministry of Defence of India considers, that the probable reason of accident Су-30МКИ in state of Rajasthan on April, 30th this year became failure in an electronic control system of a fighter. In the written answer published today to inquiry in Advice of staffs (the upper chamber of parliament) the chapter of military department Arakkaparambil Anthony has recognized, that such conclusion is made " on the basis of the lead preliminary investigation of incident ". As a result of failure - the first operation for history of this plane in the Indian military-air forces - one of pilots was lost.

According to minister after this flights Су-30МКИ have been stopped by incident for three weeks. Thus it has emphasized, that the Air Forces have no any claims to this fighter. " There are no attributes some serious problems in service of this plane in the Indian Air Forces or any insufficient delivery of spare parts which could serve as the reason of accident ", - Anthony has declared

Earlier in local press referring to the Indian military sources it was informed, that the reason of destruction of a fighter could become the human mistake admitted at piloting. The group of the Russian experts participated in investigation also has come to such conclusion. The final report on results of trial is not presented yet because of delays in decoding data recording a recorder.

According to bilateral contracts, Су-30МКИ are delivered by Russia both in a condition ready to flights, and in the form of which pass assembly at the enterprise of leading state aviabuilding corporation of. According to last data of the Indian press, in structure of the Air Forces of the country it is already totaled about hundred such fighters. To 2015 about 230 units are planned to increase this park.

Juggi G · Post by **Juggi G** » 23 Jul 2009 19:43

Sukhoi Crash: Govt Admits Fault in Flight Control System
The Indian Express

Sukhoi Crash: Govt Admits Fault in Flight Control System
Manu Pubby
Posted online: Thursday , July 23, 2009 at 0201 hrs

New Delhi : Almost two months after its most advanced fighter aircraft crashed in mysterious circumstances killing a pilot, the government has admitted that faults in the Russian origin ‘fly-by-wire’ flight control system led to the Su 30 MKI crash. Coming clean on the post-crash investigation, Defence Minister A K Antony said while there are no serious maintenance problems with the aircraft, the fleet was grounded for three weeks to ascertain the cause of the crash.

“The preliminary investigation into the accident reveals that the reason for the crash of the Su 30 MKI fighter aircraft is the likely failure of the fly-by-wire system,” Antony told the Rajya Sabha in reply to a question on the crash.

The government’s first official clarification on the reason behind the crash flies in the face of reports that the accident was caused due to a human error when the pilot of the fighter incorrectly pulled a switch that sent the aircraft into an uncontrollable spin.

Sources said while the Russian team, which was called in to help with the investigations, was quick to give the aircraft a clean chit and put the blame on human failure, deeper investigations pointed to a fault in the flight control system.

As first reported by this newspaper, the probe had narrowed down to a possible flaw in the flight control systems that caused the aircraft to go into an uncontrollable spin. This had come as a surprise because the system has quadruple redundancy, which means that it is backed up four times.

Antony said the Su 30 MKI is a good fighter aircraft and remedial measures were taken after the crash to make the fighters fully operational. “The issues derived from preliminary investigation after the crash were addressed. The Su 30 MKI is a modern fighter aircraft that has performed very well,” he said.

It has been almost two months since the fighter, which was on a routine sortie, crashed on April 30. The final investigation report has not yet been finalised due to difficulties in analysing data from the black box. The black box was recovered after the crash and was sent to England for forensic examination. The report is taking time as investigators are struggling to recover last minute data from the badly damaged equipment.

Andrew DeCristofaro · Post by **Andrew DeCristofaro** » 23 Jul 2009 20:05

OT post deleted.

Rahul M · Post by **Rahul M** » 23 Jul 2009 20:19

and how is that bit of info relevant in this thread ?
kindly delete it and post in appropriate thread.

NRao · Post by **NRao** » 23 Jul 2009 21:42

The government’s first official clarification on the reason behind the crash flies in the face of reports that the accident was caused due to a human error when the pilot of the fighter incorrectly pulled a switch that sent the aircraft into an uncontrollable spin.

Sources said while the Russian team, which was called in to help with the investigations, was quick to give the aircraft a clean chit and put the blame on human failure, deeper investigations pointed to a fault in the flight control system.

As first reported by this newspaper, the probe had narrowed down to a possible flaw in the flight control systems that caused the aircraft to go into an uncontrollable spin. This had come as a surprise because the system has quadruple redundancy, which means that it is backed up four times.

Man-O-man. The redundancy would have ensured that the fault would have been completed even if three of them failed!

Something is wrong here. IIRC the "switch" was related to an important computer. IF that computer was switched off, then no matter what the plane would go into a "spin". I THINK the computer was responsible for the FBW. IF true, so comp, no FBW. So, how is the FBW at "fault"? The spin was caused because there was no FBW - therefore no topic of a "faulty" FBW.

Either move the switch or ensure that while in flight no one can tuen it off.

ramana · Post by **ramana** » 24 Jul 2009 03:15

NRaogaru,
From the Mil Flt Safety thread posted on 26 June 2009

RaviBg wrote:I am posting this article in full as it contains many details not known till now.

IAF taking steps to prevent another SU-30MKI crash

IAF taking steps to prevent another SU-30MKI crash

Ravi Sharma

Crash in April resulted in the entire fleet being grounded

Aircraft needs to be better covered to prevent heat soak due to exposure to sun

There are calls for design change including wire-locking the switches in cockpit

BANGALORE: The Indian Air Force is initiating steps aimed at preventing another SU-30MKI crash like the one that occurred near Jaisalmer in April during a routine air exercise, killing the co-pilot and destroying a Rs. 200-crore fighter aircraft.

Highly placed sources in the Ministry of Defence told The Hindu that a joint probe by Indian and Russian Defence and flight engineers zeroed-in on the causes for the crash and suggested remedial action.

While one step will involve better covering of the aircraft when they are parked on the tarmac under to prevent heat soak, the other calls for design change, including wire-locking the switches in the cockpit that control power supply to the aircraft’s flight control computer.

The crash of the long range, high endurance SU-30MKI, the Indian Air Force’s most modern and lethal fighter, sent both the IAF and the aircraft designers, Russia’s Sukhoi Design Bureau, into a tizzy given the fighter’s exceptional and unrivalled flight safety record. The crash also forced the IAF to ground its entire Sukhoi fleet temporarily, compromising the country’s airpower.

The Court of Inquiry (CoI) that went into the crash found that the pilot, Wing Commander S. V. Munje, inadvertently switched-off the four switches that control the power supply to the computer. Switching-off the power not only cuts off the power supply to the computer, but is also irreversible. Switching them on does not ‘power on’ the all important unit.

The aircraft went into a forward bunt, lost control and crashed, killing Wing Commander P. S. Nara, an officer from the IAF’s Directorate of Air Staff Inspection (DASI).

During the flight, the aircraft is said to have experienced a technical glitch after a round of firing practice. The pilot, who was also under routine inspection by the DASI, is said to have then tried to switch-off the armament master switches, which are located just behind the pilot’s seat and in close proximity to the switches that control power to the flight control computer.

Though the CoI’s conclusion was that the crash occurred due to pilot error, a number of officials are questioning the placing of critical switches that are not to be used during in flight and only for power on when the aircraft is on theground in the cockpit and also, the inadequate in-built safety mechanisms like a wire lock or even a covering flap.

Said a former SU-30MKI pilot: “It is unpardonable and a poor design to have such critical switches, which are not to be used by the pilot in such an accessible manner. The Air Force should insist on design changes.”

The probe also revealed that the ejection seat’s harness had broken, leading to the death of Wing Commander Nara.

The reason for the breaking is being attributed to material failure of the harness due to exposure to the sun. The IAF has taken steps to have the aircraft more adequately covered.

The Ind Exp fellow is sensationalizing the story.

rajsunder · Post by **rajsunder** » 24 Jul 2009 04:05

As first reported by this newspaper, the probe had narrowed down to a possible flaw in the flight control systems that caused the aircraft to go into an uncontrollable spin. This had come as a surprise because the system has quadruple redundancy, which means that it is backed up four times.

BTW is the quad redundancy of the fly by wire implemented using the same hardware and same software platform 4 times or a combination of hardware and software platforms .
Because if its 4 copies of same software & hardware and if there was ever a logical error in the coding of FBW system, then it does not matter if we have quad redundancy or deca(10) redundancy, crashes are bound to happen.

shiv · Post by **shiv** » 24 Jul 2009 06:38

rajsunder wrote:
As first reported by this newspaper, the probe had narrowed down to a possible flaw in the flight control systems that caused the aircraft to go into an uncontrollable spin. This had come as a surprise because the system has quadruple redundancy, which means that it is backed up four times.
BTW is the quad redundancy of the fly by wire implemented using the same hardware and same software platform 4 times or a combination of hardware and software platforms .
Because if its 4 copies of same software & hardware and if there was ever a logical error in the coding of FBW system, then it does not matter if we have quad redundancy or deca(10) redundancy, crashes are bound to happen.

Having heard this story right from the beginning, I am just wondering if there is an element of psy-ops here. Let me explain from the informed layman viewpoint.

The theory we are told is thus: "You have 4 separate teams writing the code so that the chances of any one team duplicating the errors of another team is minimized. Unlike the "same code X 4 times where the errors made by one team are merely repeated. Therefore the former is safe and the latter is less safe."

This story has been doing the rounds for at least a couple of decades now and in the meantime I have heard of at least some instances in which planes have been flying safely with duplicated code from the same team. I am sure designers have had enough time to validate this by simulating using the same code 3 or 4 times repeated. After all the "comfort" of having 4 teams is not good enough - it would be preferable if none of the codes had any errors in the first place.

I was under the impression that software testing and validation techniques had been refined to the extent that mysterious unknown errors are less unlikely. Besides - when you look at newer concepts like cloud computing and the use of networks for processing power you are often using the same code across platforms and the results from these are thought to be accurate enough - so what is the need for carrying on with this charming fairy tale of "4 different teams-4 different software codes". This is a charming fairy tale from the 1970s - but I am not at all sure that its validity today is as vital as it seemed when the story first came out. Like "strategic bombing" and "bomb truck" this appears to be yet another legend that never goes away despite possibly being beyond its sell by date.

putnanja · Post by **putnanja** » 24 Jul 2009 06:59

Shiv, I will not dismiss the redundancy factor lightly. Software has always had errors where ever they were. It is just that in the MIL standard, it is tested a bit more rigorously. If you have identical machines and code in multiple places and if they get the same input, chances are they produce the same result.

NRao · Post by **NRao** » 24 Jul 2009 07:04

Thanks R.

the other calls for design change, including wire-locking the switches in the cockpit that control power supply to the aircraft’s flight control computer.

Cool. That makes sense. Simple, cheap and easy to implement if they go with that.

BTW is the quad redundancy of the fly by wire implemented using the same hardware and same software platform 4 times or a combination of hardware and software platforms .
...............

I think the MKI (as do other ACs) has one flight control computer (GJMan?), but has more than one (in this case 4) means to ensure that the decision is acted upon. So, if one path from the computer to the destination fails, it has three other routes.

Didn't the Grippen that crashed have a problem with its code?

It is only on the space shuttle (and the like) that they have multiple computers and the majority decision is implemented.

Rahul M · Post by **Rahul M** » 24 Jul 2009 08:09

The theory we are told is thus: "You have 4 separate teams writing the code so that the chances of any one team duplicating the errors of another team is minimized. Unlike the "same code X 4 times where the errors made by one team are merely repeated. Therefore the former is safe and the latter is less safe."

it is not necessary that quad redundancy would have 4 diff SW. IIRC the AI-09 reports brought back back that LCA uses only one version of code in its FCS while the gripen has three unless my memory is playing tricks.
(I had in fact intended to ask the same question for the Su-30 but forgot to do so !)
such a system would still have quad HW redundancy. for a robust and reliable SW that's not necessarily a bad thing. I'm not sure how different the claimed 3 versions are in gripen, for example, as that would mean 3 complete set of flight tests == 3 times the effort, time and money.

someone more conversant with the aero industry would have to answer these questions.

coming back to the su-30 crash, what I find hard to believe is the claim that after so many hours of testing and a decade of service the mki FCS has errors in some regimes (since it works perfectly well most of the time)
surely that should have been discovered by now ?

shiv · Post by **shiv** » 24 Jul 2009 08:11

RaviBg wrote:Shiv, I will not dismiss the redundancy factor lightly. Software has always had errors where ever they were. It is just that in the MIL standard, it is tested a bit more rigorously. If you have identical machines and code in multiple places and if they get the same input, chances are they produce the same result.

Not disputing that.

But there is a way of dealing with such info and that is to validate and see if the assumption is correct.

For example if an experiment can do a simulation for 10 million hours with "different code" and repeat the same with "same code" one could say "OK after 10 million hours of simulation the "different code" came up with x errors and "same code" came up with Y errors and the difference was statistically significant. What if both return zero errors? What does the conclusion mean?

This is basic standard research stuff and is deigned to improve any systems by finding out more. Surely this must have been done by someone? Where are the reports? For how many more decades are teh technical experts of FBW in the world going to go around basing their need to have 4 different sofwtare teams on unvalidated impressions that "Software will always have errors and therefore let us be safe and include 4 different codes.

How about 3 teams rather than four? How about two and two? Just two teams doubled. That would cover both coding and hardware errors

I would have thought that studies to reveal the validity or otherwise of age old assumptions is the fundamental driving force behind progress. What evidence exists to say that in real life the code by 4 teams is safer than 4x code by one team? The point I am making is that i am being told the same assumption for decades without any sign of anyone trying to find out if it is a valid assumption by dispassionate research rather than an emotion laden assumption.

shiv · Post by **shiv** » 24 Jul 2009 08:35

Sorry to stay OT - my last post on this.

Googling for info tells me that "software from different teams" is the exception rather than the norm. Software development for FBW has reached levels of safety unknown in ordinary consumer level apps. Most often it s just one set of fail safe code.

I am in the myth destroying mode and would like this myth to be cleared up along with the myths associated with "strategic bombing" and "bomb trucks"

merlin · Post by **merlin** » 24 Jul 2009 15:52

A more practical problem - how are you going to get 4 teams that have the experience and expertise to develop complex FCS software in India?
How many companies worldwide have this expertise? How many teams are there in each of these companies?

shiv · Post by **shiv** » 24 Jul 2009 17:06

merlin wrote:A more practical problem - how are you going to get 4 teams that have the experience and expertise to develop complex FCS software in India?
How many companies worldwide have this expertise? How many teams are there in each of these companies?

Merlin again Google helps in pointing out that FBW software adds to the cost of development like nothing else. I am sure this "four different teams" story is now old enough to be relegated to the story books.

I did read that the Space shuttle had one set of backup s/w written by a different team, but there are refs that show how software is tested and validated to be basically fail proof under any circumstances. All this business of "Oh if one team makes an error then the other team is unlikely to have made one" is no longer the reality.

NRao · Post by **NRao** » 24 Jul 2009 21:16

An excellent paper on the Grippen system:

http://www.pdfee.com/usage-of-ada-in-th ... ystem.html

(Use the "download" to read the two page paper.)

Grippen uses

The flight control system has three redundant channels.
Identical software resides in the channels, and each channel
contains the following two processors:
• Primary processor (MC68040).
• Input/Output and backup processor (TMS320C30).

So, there are three "channels", each having two processors, and, each hosting the same (identical) software (no three teams of software).

BUT, as in the case of the shuttle, there is voting between these channels:

The aircraft has an electrical (fly-by-wire) flight control
system, which performs input signal conditioning and
voting, control law computations, functional monitoring and
redundancy management, data recording, etc.

I do not recall this being the case with either the MKI or the LCA.

NRao · Post by **NRao** » 24 Jul 2009 21:18

I know for a fact that the F-16 - the very first AC to use OO - used one team and C++.

The above Grippen article states that they used Ada (which was the first preferred language of the US DefDept, IIRC they funded it).

But multiple teams would be a disaster IMHO. You will also need triplicate of everything - testing platforms, etc, BEFORE they load it on a single air craft.

negi · Post by **negi** » 25 Jul 2009 00:05

NRao sir I guess C++ caught up with the defense sector too late for F-16 team to use it; I think DOD came up with ADA initiative specifically for writing flight control SW and similar apps and most probably was a default choice for most of the platforms built in 80's .

NRao · Post by **NRao** » 25 Jul 2009 01:40

negi,

You are right about Ada. But that predates C++ (I used it to learn AI!!! Today I am trying to sell those books on Amazon.

. Pristine condition if anyone wants them.).

However, remember Booch and his Patterns? It was his application of C++ (which they say would have died very quietly if it was not for this effort - and its success) to the F-16 project that made him "famous".

From here is a very funny incident:

5. Such as the F-16 bug that caused the plane to turn upside down when it crossed the equator.

What is funny is that LM built the F-16, and, .............................................. the F-22, which when it crossed the International Date Line had problems. LM!!!!

Booch's contribution was to using C++ for RT systems.

Avionics. Fun stuff.

NRao · Post by **NRao** » 25 Jul 2009 01:45

FYI Only, MKI uses Ada

Vikram_S · Post by **Vikram_S** » 25 Jul 2009 02:32

NRao

Even MKI & LCA will use voting, its a fundamental basis of Quad FBW systems used worldwide

The FBW systems are designed to incredibly high standards using the benchmark PLOC (Probability of loss of control)
LCA PLOC is 10^-7

MKI will be similar, the Quad FBW standard followed is of the same order

LCA FBW and reliability data:

Dual redundant MC/DC
Dual redundant processor based USMS
Quad FCS- details given above
Engine control with dual back up modes
Dual hydraulic power lines
Target reliability 95%
Quad electric power
Dual redundant fuel feed pumps
Dual redundant 1553 Databus

NRao · Post by **NRao** » 25 Jul 2009 03:09

VS,

You seem to know more than I.

However, please refer to SUKHOI 30MKI PROJECT VETRIVALE

The expected size of the Su-30MKI fleet of IAF is around 180 aircraft. A very beneficial effect of this approach, in the IAF entrusting all of the core avionics to a single development agency, is that DRDO has been able to design the 3 on-board computers with maximum commonality of hardware and software amongst them using a modular approach to design. This obviously results in major cost and time savings in development; it also benefits the user in maintenance and spares inventories. In fact the DRDO has gone a step further and come out with a new design of the Core Avionics Computer (CAC) which can be used with a single module adaptation across many other aircraft platforms. Thus the CAC which is derived from the computers designed for the Su-30MKI will now be the centre piece of the avionics upgrades for the MiG-27 and Jaguar aircraft as well.

What is your take?

NRao · Post by **NRao** » 25 Jul 2009 05:24

VS,

The digital FBW system of the LCA is built around a quadruplex redundant architecture to give it a fail op-fail op-fail safe capability. It employs a powerful Digital Flight Control Computer (DFCC) comprising four computing channels, each powered by an independent power supply and all housed in a single line replaceable unit (LRU). The system is designed to meet a probability of loss of control of better than 1x10-7 per flight hour. The DFCC channels are built around 32-bit microprocessors and use a safe subset of Ada language for the implementation of software. The DFCC receives signals from quad rate, acceleration sensors, pilot control stick, rudder pedal, triplex air data system, dual air flow angle sensors, etc. The DFCC channels excite and control the elevon, rudder and leading edge slat hydraulic actuators. The computer interfaces with pilot display elements like multifunction displays through MIL-STD-1553B avionics bus and RS 422 serial link.

Yogi_G · Post by **Yogi_G** » 25 Jul 2009 08:51

The DFCC channels are built around 32-bit microprocessors and use a safe subset of Ada language for the implementation of software. The DFCC receives signals from quad rate, acceleration sensors, pilot control stick, rudder pedal, triplex air data system, dual air flow angle sensors, etc.

I wonder what they mean by a safe subset, I remember reading this article a long time back....

I Have a Feeling We're Not In Emerald City Anymore

Drevin · Post by **Drevin** » 25 Jul 2009 10:44

Is it true that wrt the su30mki we are bypassing the irbis upgrade in favor of aesa. I've been hearing in many posts that the mlu could very well just be a pesa snow leapord/irbis. Can anyone confirm the future directions for the mki.

Cain Marko · Post by **Cain Marko** » 25 Jul 2009 10:48

If the next jump was the Irbis, we'd have heard something official by now. My guess is that the Bars Mk3 is goood enough for now; next upg will probly be AESA. JMT

CM.

ArmenT · Post by **ArmenT** » 25 Jul 2009 12:14

Aviation industry tends to use DO-178B/EUROCAE ED-12B standard for software and DO-254 standard for hardware. The wikipedia links have other links to actual standards documents, certifying agencies and such.

A bunch of manufactures (mostly Japanese) came up with guidelines for writing embedded software in C++. See this url for more details. This standard uses a subset of C++ and tries to avoid some of C++'s more heavyweight features. Freescale is one such manufacturer that provides a C++ compiler that compiles to this standard. Not everyone agrees with this standard though.

New DoD guidelines for C++ can be found in Joint Strike Fighter Air Vehicle C++ Coding Standards (PDF file).

None of this has anything to do with Su30 of course, so pardon the intrusion onlee. My first and last word on this subject.

Vikram_S · Post by **Vikram_S** » 25 Jul 2009 21:06

NRaoji

those computers are display processor, mission computer and hot standby, with radar computers also.
they do have max commonality of hardware and software, and were developed using LCA technology.
the computers do not include FBW computer, that is provided by russians only as part of sdu-10 mk fbw control system.

about computing channels, that is the usual terms, all quad FBW systems have 4 computing channels with duplicate hardware and software for redundancy and removing the faulty channel easily in case there is fault.
other approaches are to lessen number of channels but split it between analog and digital or make three diffrent channels with different hardware software (practically nobody does this last approach in todays world, imagine problems in maintaining, improving 3 different FBW systems ).
Quad digital FBW approach is now generally taken as safe, reliable and generally most efficient way to implement FBW system in given amount of time.

George J · Post by **George J** » 26 Jul 2009 00:14

I am not current with my MKI stuff...so unless things have changed..........the MKI uses the Elara SDU-10MK FCS. The RC1/2, MC and other stuff belong to us but not the FCS.

Cain Marko · Post by **Cain Marko** » 26 Jul 2009 09:13

OK can any guru explain this to me, totally conphuzed onlee!

It is said that the F-16 has some of the best turn rates (sustained) @ high speeds in 4 gen a/c. The F-15 too is no slouch. The su-27 is supposedly better than the f-15 and the eurocanards are probly the best as of today (apart from the raptor). In terms of snap manouvering and ITRs the russkis have always been excellent (both the fulcrum/flanker), the mirage too is supposedly v.good.

but then, i was reading vishnu som's rebuttal of col.fornoff's indiscretion and he mentions 35 deg STRs for the MKI thanks to its TVC. I am guessing this would be at substantially lower speeds? In fact he mentions elsewhere that a/c with TVC really have no real limitations

Does TVC help in turning at supersonic speeds? From all internet jocks, all one hears is that it is only great for slow speed, airshow manouvering. No real difference where it matters. Obviously if that was the case, the IAF and the russkis woudn't be offering it on airframes that are already exceptionally manouverable @ low speeds and can do cobra types without the TVC. Whats the catch?

Thanks all.

CM.

Added later: Here is one article that I found useful
http://www.codeonemagazine.com/archives ... 2a_94.html

negi · Post by **negi** » 26 Jul 2009 09:43

^ The 'G' rating of the airframe exactly tells you about how much can you turn or maneuver an AC at a given speed; imagine the mechanical stress which an airframe will have to bear if it were to somehow pull a COBRA at Mach 1+ . And lastly even if an airframe is built to negotiate higher G's the human capacity to function under high G loads will still be a limiting factor.

Does TVC help in turning at supersonic speeds?

I don't think that TVC is engaged in the supersonic regime . Even in the subsonic regime TVC is employed momentarily to point the nose of the aircraft in a given direction (I have only seen TVC being employed for longer duration when the MKI does the backflip ..but thats in airshows ) .

Aditya_M · Post by **Aditya_M** » 26 Jul 2009 21:02

Some comments about software coding and such (I'm studying avionics):

- Different teams working independently is the norm for big projects. Boeing does it, Airbus did it from the word go (A320). So much so that the 11 FCCs (286-era) on the A320 had many overlapping functions and were made by different manufacturers. Incidentally, Intel shut down its last line of 286-class microcomputers, the last batch of which was purchased by Airbus. Next stop, A-3X0.

- ADA - the company, not the language - uses identical computers with one team writing the code. All computers *don't* have identical software, they are designed to degrade gracefully giving the pilot more control through successive failures. If, though, all four fail - oops.

- ADA - the language, not the company - may be old, but is the most preferred secure programming language in the world. The reason for this is it is a bl**dy rigid language that does not allow you a lot of flexibility to code in, which ensures you don't make too many mistakes. However, other languages are becoming more popular (SAAB started out with a modified PASCAL!) simply because today testing is so rigorous that almost everything is caught in functional testing. DO-178 and DO-254 class A requires you to demonstrate that your system won't fail more than once every billion hours. This is impossible, so everyone develops parallel computing and codes that are required to demonstrate one in ten thousand (class C). Three such parallel computers equal a catastrophic failure probability of 10^-12 which fulfils class A requirements.

JaiS · Post by **JaiS** » 29 Jul 2009 06:20

IAF presses HAL for more Sukhois

Keen to deploy its most potent fighter jets at strategic airbases on both the eastern and western fronts, IAF has asked Hindustan Aeronautics Ltd (HAL) to step up the production rate of the Russian-origin Sukhoi-30MKIs.

IAF till now has inducted 98 of the 230 twin-engine Sukhois contracted from Russia, with HAL tasked to manufacture 140 of them under transfer of technology, under three deals worth a total of around $8.5 billion. IAF wants HAL to step up the production rate from the current 14 to at least 18 Sukhois per year, as also "not bunch them towards the end of the year", said a senior officer.

IAF, however, may be forced to go in for another deal for the ‘heavy’ category Sukhois if the gigantic $10.4-billion project to acquire 126 new ‘medium’ multi-role fighter aircraft and the proposed induction of seven squadrons (18 jets each) of the indigenous ‘‘light-weight’’ Tejas Light Combat Aircraft are ‘‘delayed beyond a reasonable timeframe’’.