LCA Tejas: News and Discussions

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shiv
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Re: LCA Tejas: News and Discussions

Postby shiv » 13 Sep 2016 20:22

JTull wrote:
Rahul M wrote:isn't that the opposite of the point being made ? that we downplay our strengths and multiply negativity ?


I'm talking of the 'I told you so' attitude. Talk is cheap and we, as Indians, do that a lot. Just look at the success of this forum... :D

At the risk of carrying on with a digression I think both are correct. There is a lot of negativity and criticism about others, but a very large number of Indians do not count themselves personally with "the others" and consider themselves great successes. But like Narayanmurthy's quote, this is the highest ego per unit achievement when you consider the quantum of success. The biggest egos talk of their personal (often financial) success.

And yes it has been seen a lot over the years even on BRF.

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Re: LCA Tejas: News and Discussions

Postby Dennis » 14 Sep 2016 01:44

To complement the excellent technical inputs from Indranilroy and JayS related to the LEVCONs, here's a couple of pics of the LEVCONs on the machine itself, and the team that flies and tests them.

Picture 1

Picture 2

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Re: LCA Tejas: News and Discussions

Postby disha » 14 Sep 2016 02:13

Dennis'ji - can you please post the fotus in NLCA thread as well? Once I am free - will consolidate some of the discussions in NLCA thread as well.

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Re: LCA Tejas: News and Discussions

Postby Bhaskar_T » 14 Sep 2016 11:21

What is so difficult for Manohar Parrikar in approving a 2nd production line for LCA Tejas? It may take 2-3 years to establish this line and Mk1A may appear by that time. If not Mk1A, IAF might import more Mk1s or they can be exported to Vietnam or Sri Lanka.

Neither Mk1A is being talked about nor increasing the production capacity of Tejas line is getting any steam.

No news for FOC too. Absolutely disturbing it is.

shiv
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Re: LCA Tejas: News and Discussions

Postby shiv » 14 Sep 2016 17:14

Bhaskar_T wrote:What is so difficult for Manohar Parrikar in approving a 2nd production line for LCA Tejas? It may take 2-3 years to establish this line and Mk1A may appear by that time. If not Mk1A, IAF might import more Mk1s or they can be exported to Vietnam or Sri Lanka.

Neither Mk1A is being talked about nor increasing the production capacity of Tejas line is getting any steam.

No news for FOC too. Absolutely disturbing it is.

My take from an interview of the HAL MD on TV. It's not in Parikkar's hands.

HAL is in the unfortunate situation of having to make planes from raw material. The best companies in the world have Tier 1 manufacturers taking raw material and making a product. That product is readied for manufacture by a tier 2/3 manufacturer and this entity supplies a readymade component to HAL for integration into an airframe. Unfortunately most of the 2500 private Indian players are Tier 1 manufacturers and the final component has to be made in HAL and then integrated. The MD said that it would be much better if HAL could stick to integration and testing of finished planes rather than manufacturing everything from raw metal ore or fibre.

Under these circumstances HAL can expand to 8 LCA per year and later 16 per year. Anything beyond that is impossible unless other companies step forward and are interested in producing finished parts for the defence industry. Note that HAL itself serves as a tier 3 manufacturer for Airbus etc producing doors and parts of wings. That work should be done by smaller specialized Indian companies

Personally I agree that no aerospace company should be taking raw metal ore and later turning it into an aircraft. It is an industrial complex that needs to do that - not one behemoth do it all company. But there are no other companies right now and it will be a slow painful process as pvt companies join the list

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Re: LCA Tejas: News and Discussions

Postby JTull » 14 Sep 2016 17:46

Yes, shiv, I too read that interview.

But, I am also aware of the lament of private companies that making investment in production capabilities and getting a certification without any firm orders is pointless. The onus is on HAL to build that ecosystem which it says it wants. ISRO is beginning to do it. And, auto companies are adept at it. History tells us that people at HAL don't want to relinquish the control despite their public declarations to the contrary.

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Re: LCA Tejas: News and Discussions

Postby shiv » 14 Sep 2016 17:50

Looks like there is a chicken or egg situation. I get the impression that order numbers are low and government contracts take ages to pay up and it becomes a huge risk for private companies. Delays in turn keep order numbers low. Also - god only knows how much "quiet corruption" happens where a company of a nephew of a friend of a HAL babu gets a contract over and above some other bidder. The knot is extremely tight and dense

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Re: LCA Tejas: News and Discussions

Postby JTull » 14 Sep 2016 17:58

IMHO, HAL needs to move away from sourcing 50,000 parts to say 500. Let them invite L&T, Tatas, Godrej, BEL and the like to build entire wings, landing gears, etc. with all the sub-assemblies.

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Re: LCA Tejas: News and Discussions

Postby Bhaskar_T » 14 Sep 2016 19:45

shiv wrote:Under these circumstances HAL can expand to 8 LCA per year and later 16 per year.


Shiv - I agree with your reply but am only asking for Parrikar's fast approval for 16/year. I don't know how many times I have tweeted to him but obviously unlike Swamy, Parrikar ji never ever even once responds to junta tweets.

Unless 16/year is approved, how HAL will ink contracts with manufacturer's! HAL/MOD are going very slow on this.

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Re: LCA Tejas: News and Discussions

Postby JayS » 16 Sep 2016 11:55

From FB page, regarding the placement of the IFR probe:

Yes, on the right side traditions place

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Re: LCA Tejas: News and Discussions

Postby maitya » 16 Sep 2016 12:55

^^^^^^^^^
The query-answer-sequence was:
Q: Also where in the LCA fuselage will the IFR probe be fitted (already fitted in LSP-8?) - in the "traditional" position of on the right side of the aircraft, almost at the front-edge of the canopy (as seen here, for example, https://babsblog.files.wordpress.com/20 ... as-lca.jpg) or bang-in front of the canopy?

Tejas - LCA: Yes, on the right side traditions place


This should resolve the issue of the IFR placement (shivji, pls note).

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Re: LCA Tejas: News and Discussions

Postby SaiK » 16 Sep 2016 14:05

Rafale is overshadowing LCA Mk2++ and AMCA needs

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Re: LCA Tejas: News and Discussions

Postby ragupta » 16 Sep 2016 15:33

SaiK wrote:Rafale is overshadowing LCA Mk2++ and AMCA needs

How?

Limited buy of Rafale is a hedge against other buys from Super powers. Whether Russian or yet to be signed US weapon delivery platform F1x.
The need is for a mature platform now.
One thing at a time, there is no unlimited money.

Just because there is a thinking, design and computer model, means it is ready for production. This is a long term goal, and lot of work needs to be done. Many sub systems have to designed and proven.

In the meantime there is a need to involve private players, build incremental capacity. This is what is being envisaged through this deals.

Typically French systems are costlier than Russian and American due to volume of production, but they have good equipment and solid performance.

There is worry on the pace of indigenization, but that will pick pace when there is private sector capability. in the meantime, work must go on indigenous systems and at the same time mature system procured for armed forces, for another 5 to 10 years.

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Re: LCA Tejas: News and Discussions

Postby SaiK » 16 Sep 2016 16:49

^"worry on the pace of indigenization"

should trigger to how to?

from concurrent engineering to maturity, we have been moving slow. we need more investments there.
following on Rafale, you will soon see how money is spent by IAF for PAKFA and MKI upgrades.

home grown will be homing on IAF for the next decade

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Re: LCA Tejas: News and Discussions

Postby suryag » 23 Sep 2016 08:36

SP-3 to take to skies in a week

can anyone elaborate on these pipelines vis-a-vis interchangeability(what does that mean, okie i understand the literal meaning)

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Re: LCA Tejas: News and Discussions

Postby rahulm » 23 Sep 2016 09:29

There is a lack of standardisation of panels, plumbing and wiring upto and including LSP2 and both NLCA even though the drawings for LSP series have been frozen.

This means so far each aircraft Is unique in panels, plumbing and wiring and swapping these without tinkering is not possible - yet.

The reasons for this state are many-including the fact that they are hand made and variable worker skill levels with attention to detail.this should, eventually, be sorted.

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Re: LCA Tejas: News and Discussions

Postby Kakkaji » 24 Sep 2016 03:23

As India inks Rafale deal, 3rd LCA for IAF nearly ready

The LCA Series+ Production-3 (SP-3) underwent the low-speed taxi trials (LSTT) on Friday, and the high-speed taxi trials (HSTT) are scheduled in the next couple of days. In a week, the aircraft will see its first flight.

However, the acceptation by IAF+ may take a little longer given the fact that Air Force Day (October 8 ) preparations are keeping the force busy. LCA will for the first time fly over the Hindon Airbase as part of the Air Force Day.

The engine ground run was completed+ recently, and sources said that a significant portion of the SP-3 now has interchangeability standards complies with higher standards—ensuring easy replacement of components without needing design changes or affecting operational performance.

Source said that there will be three main sorties that need to be performed before the flight is deemed ready for IAF+ to accept. "Each of these sorties will check specific parametres of the aircraft. We cannot going into details now, but these three sorties will be a must before we hand it over to IAF," one of the sources said, adding that Air Commodore (retd) KA Muthanna is likely to fly the SP-3 on its maiden flight.

For the first time, the Tejas will also take active part in the Air Force Day celebrations—it will be part of the official flypast ceremony. "No aircraft that is not inducted into the Air Force can be part of the official flypast. This year, we wanted four LCAs to fly in formation, but with only two with us and one more coming, we will have two flying and another as a static display," an IAF source said.

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Re: LCA Tejas: News and Discussions

Postby brar_w » 25 Sep 2016 18:32

Sid wrote:Although following image is from MK II model, it may be an indicator to current radome design. There seems to be a support rail which goes horizontally across the radome, end to end. But looking at more TFTA radomes from Europeans, they are void of any kind of structures inside it.

This rail can be there for either structural strength or run the ground cable from pitot tube to provide earthing. It might have interfered with radar as well.
https://s13.postimg.org/ra6k11ik7/LCA_Radar_Radome.png
Image


The picture on the right is of Raytheon's APG-63(V)3/APG-82(V)1.

http://www.raytheon.com/capabilities/products/apg82v1/

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Re: LCA Tejas: News and Discussions

Postby tsarkar » 27 Sep 2016 16:28

Following is an AW&ST article on AoA, in context of our discussion here

http://aviationweek.com/business-aviati ... -indicator

Understanding The Angle-Of-Attack Indicator
Sep 22, 2016 Fred George | Business & Commercial Aviation

Understanding Angle of Attack

The FAA has been actively promoting angle-of-attack (AoA) indication systems as a means of reducing general aviation loss of control (LOC) accidents for several years. An analysis of nearly 2,500 general aviation accidents that occurred from 2001 to 2010, mostly in light aircraft, pointed to LOC as the leading cause of the mishaps, which killed 1,259 people during that period. LOC accidents continue to kill about 175 people in general aviation aircraft every year. An FAA working group concluded that AoA systems could help reduce the incidence of these accidents and save lives.

Government regulatory and accident investigation agencies also believe AoA indication systems have the potential for improving safety in jets. A series of upsets in commercial aircraft, including the crash of Air France Flight 447 in June 2009 that killed all 216 people on board, also piqued renewed industry interest in AoA indicators for civil jets as well as focusing on the need for upset recovery training.

France’s Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile (BEA), the agency that investigated the AF447 accident, recommends “that EASA and the FAA evaluate the relevance of requiring the presence of an angle-of-attack indicator directly accessible to pilots on board airplanes.”

The pilots of that ill-fated Airbus A330 lost control of the aircraft at FL 350 in night IMC over the Atlantic Ocean north of Brazil, when the pitot tubes likely became obstructed with ice crystals, causing the aircraft’s primary flight displays, digital fly-by-wire (FBW) flight control system and autopilot to become degraded or inoperative.

Pitot tube icing also caused the A330’s digital FBW system to lose its normal control law functionality, including flight envelope protection. The system downgraded to an alternate law in which there was stall warning, but no stall protection.
tsarkar wrote:Note for those who believe that FCS is foolproof


The startled and confused pilots made erroneous control inputs, causing the aircraft to climb quickly above its lift ceiling, according to the BEA. The stall warning system briefly was triggered twice during the ascent. Then the stall warning came on continuously as the aircraft reached about 6 deg. AoA. But the crew was apparently unaware of their hazardous situation.

The nose-up sidestick inputs also caused the elevator to trim nose up. The aircraft subsequently entered into a fully stalled condition, with pitch attitude at 15-deg. nose up and AoA pegged at 35 to 40 deg. as the aircraft plunged toward the ocean at more than 10,000 ft. per minute.

Passing through FL 350, the aircraft decelerated so precipitously that the stall warning system transitioned from the air to the ground mode, causing the stall warning system to silence. The pilot flying finally pushed the sidestick forward, causing airspeed to increase and again triggering stall warning as the stall warning system went back into the air mode.

But it was too late. Little more than 4 min. after the big screens went blank, the aircraft crashed into the water at a descent rate of nearly 11,000 fpm and with a forward speed of only 107 kt.

The BEA notes that the crew of AF447 “never formally identified the stall situation” and that AoA indications were “not directly accessible to the pilots. Thus, “It is essential in order to ensure flight safety to reduce the angle of attack when a stall is imminent. Only a direct readout of the angle of attack could enable crews to rapidly identify the aerodynamic situation of the airplane and take the actions that may be required.”

But few current production civil jets have direct AoA readouts. On most models, AoA mostly is used to drive stall margin and wind-shear escape indicators. Boeing, though, notes that AoA has been “a key aeronautical-engineering parameter” and is “fundamental to understanding . . . performance, stability and control.”

Angle of attack may be defined as the angle between the wing’s mean aerodynamic chord and the relative wind or flight path vector. Wing leading edge upwash and trailing edge downwash, among other factors, determine the true AoA of the wing. But aboard most jets, it’s measured indirectly, as AoA sensors typically are mounted on the nose or forward fuselage of the aircraft, rather than on the wing.

The FAA says that AoA is “a better parameter to use in avoiding a stall” because the airplane always will stall at the same angle of attack for a given configuration. That statement is actually incorrect. In truth, critical or stalling angle of attack also varies as a function of local Mach number over the wing, notes veteran aerodynamicist David Lednicer, vice president-engineering at Aeromechanical Solutions LLC in Redmond, Washington. The stalling AoA during high-altitude cruise may be as much as 6 deg. to 7 deg. lower than at sea-level AoA due to local Mach flow over the wing. Aboard AF447, the BEA notes that the spread between AoA in normal cruise at Mach 0.82 and stall warning was about 1.5 deg. at FL 350.

Available lift indeed is a function of angle of attack, local Mach number over the wing, air density and wing area. Holding constant other parameters, AoA is a direct measure of available lift and stall margin, assuming it’s normalized for configuration and air data inputs. AoA indicators also can respond more quickly than airspeed indicators to the effects of stick and throttle inputs. An AoA-based instrument also can respond more quickly to other variables that affect airfoil performance, such as high lift and drag device configuration changes.

AoA indicators and “indexers,” the three-color, three-symbol displays atop glareshields, long have been used by U.S. Navy aviators to control aircraft performance precisely when making carrier landings. The mantra of “Meatball [improved Fresnel lens optical landing system], Line Up [on centerline] and Angle of Attack” is drilled into the heads of student Navy aviators early in undergraduate pilot training. It’s also used as an effective gauge of lift performance during basic fighter maneuvers.

Normal and Extraordinary AoA at Low Altitude

The maximum lift that a wing can produce at a given AoA very much is determined by secondary flight control configuration, including the position of trailing edge flaps that increase wing curvature, leading edge devices (if installed) and speed brake/ground spoiler extension. Leading edge contamination, most particularly that caused by ice accretion, can cause large-scale degradations in available lift. Aircraft with relatively high wing loadings and having no leading edge devices especially are prone to reduction in available lift at high angles of attack.

At low altitude, a high-performance business jet wing may not stall until local AoA reaches 16 deg. to 18 deg., or more, depending upon high lift configuration. When extended, trailing edge flaps increase lift per degree of angle of attack, but stall actually occurs at a lower maximum AoA because of airflow separation. Leading edge slats, in contrast, enable the wing to achieve a high stalling AoA because they delay airflow separation.

During takeoff and landing, an aircraft flies relatively close to its stall margins. On takeoff, the certified one-engine-inoperative (OEI) V2 safety speed most typically ranges from 1.13 to 1.2 times the stalling speed in a given configuration. So, V2 is considerably slower than best lift-to-drag ratio. If the aircraft were allowed to accelerate to best lift-to-drag ratio, OEI climb performance would be reduced and the aircraft would not climb at the published AFM gradient.

On landing, Vref ranges from 1.23 to 1.3 Vso. As a rule of thumb, lift coefficient increases by about 0.1 for each degree of AoA increase from some reference point, but drag also rises substantially.

Virtually all business aircraft with digital FBW flight control systems have full envelope protection that prevents the aircraft from reaching aerodynamic stall or exhibiting unacceptable handling traits at high AoA. Even with the sidestick or control yoke held fully aft at low speed, the FBW system will nudge down the nose sufficiently to prevent a stall or untoward handling behaviors.

If an aircraft has a conventional flight control system and if its natural pre-stall warning doesn’t provide clear indications of the impending stall, an artificial stall warning system, such as a stick shaker and audible alert, may be required. If the aircraft doesn’t pitch down positively at the stall as a result of aerodynamic forces, a stall recovery system that forces down the elevator may be required. In older Learjets, for instance, the stick shaker is triggered at about 1.07 stall speed and the stall prevention stick pusher fires 5% before stall.

Notably, wings develop more lift per degree of AoA in ground effect, but stall, or CL max, occurs at 1.5 deg. to 2.0 deg. lower angle of attack than in free stream air. Such differences in stalling AoA must be built into the stall barrier system to provide adequate safety margins during all phases of flight.

The Safe Flight SCc Lift Transducer precisely measures the wing’s leading edge stagnation point and airflow. The Indexer Computer is an AoA indicator that incorporates LEDs in the display, making it easy to read in all lighting conditions and features a pilot adjustable Reference Marker for setting AoA targets. Credit: Safe Flight

With a fundamental understanding of AoA, it’s reasonable to ask why the aviation industry hasn’t made the transition from indicated air speed to AoA as the primary performance indicator for target V speeds. Years ago, for instance, Safe Flight Instrument Corp., a pioneer in wing lift sensors and systems since 1946, offered systems that drove the pitch command bars on electromechanical flight directors installed in certain aircraft to help pilots maintain the optimum angle of attack for V2 during a one-engine-inoperative takeoff. But airframe and avionics manufacturers backed away from such systems when they upgraded to glass cockpits and integrated avionics systems and certification rules became tougher.

Of course, Safe Flight continues to manufacture a full line of AoA and stall warning devices for aircraft ranging from light general aviation models to fully integrated ultra-long-range business jets, jetliners and military planes.

Gulfstream veteran test pilot Tom Horne points to two basic reasons for using reference V speeds rather than AoA as primary reference. First, until the advent of the new generation of solid-state pitot, AoA and yaw sensors, such as UTC Aerospace SmartProbes, AoA sensing systems couldn’t match the data integrity, functional reliability and redundancy of conventional pitot-static systems. If an AoA probe or vane iced up or suffered damage, there wasn’t a secondary, cross-side or alternate tertiary backup sensor that could be used to provide AoA information to the pilot flying. The AoA indicator just became inoperative. In contrast, most transport category aircraft have dual air data systems, plus a third backup air speed indication, providing triple redundancy.

Second, reference V speeds not only are based on optimum wing angle of attack, they also must take into account Vmca and Vmcg minimum control speeds for adequate direction control as well as minimum speeds to prevent tail strike on takeoff and/or landing. They also are predicated on maximum allowable pitch, roll and yaw control force and lift performance degradation due to probable ice accretion as defined by the Flight Into Known Icing regulations.

Takeoff and landing reference speeds thus are a balance of wing performance, stability and control requirements, and tail strike protection, among other factors. Yet, a basic tenet remains: As weight increases, so does stalling speed, resulting in an increase in reference V speeds above a minimum allowable point.

Therefore, the aviation industry still uses indicated airspeed as the primary performance reference during normal takeoffs and landings. Horne explains that aircraft manufacturers potentially could make the transition to an AoA system that could be compensated, or normalized, for all the other factors. But abandoning the time-proven V speed system could be complex and costly to develop and certify with limited tangible benefits for operators.

The reliance on reference V speeds, though, gets tossed out in the event that the flight crew has to extract maximum lift performance out of the aircraft or risk a crash, such as during a wind-shear recovery maneuver or low-altitude traffic avoidance maneuver. That’s when AoA indication systems become a primary performance reference.

But AoA indications for stall or upset recovery must be instantly intuitive. This is no time to nuance your interpretation of an angle-of-attack gauge reading as though you were a veteran Navy carrier pilot. The AoA-based PFD airspeed scale low-speed reference tapes and pitch limit indicators on civil jets provide easy-to-read cues for extracting maximum lift performance without stalling the aircraft. Such cues allow flight crews to fall back on so-called “rule-based behaviors,” according to the Netherlands’ Nationaal Lucht- en Ruimtevaartlaboratorium (National Aerospace Laboratory, NLR).

The typical technique for wind-shear escape, for instance, calls for the pilot flying initially to pitch up to 15 deg. and push up the throttles to takeoff/go-around, then follow the guidance of the pitch limit indicator (PLI) on the PFD. The NLR experimented with other techniques during six-axis simulator trials, including using AoA indicators, but nothing proved so simple and consistently effective as this rule-based behavior.

Normal and Extraordinary AoA at High Altitude

Aerodynamically, the minimum drag point occurs at the highest lift-to-drag ratio. Before the advent of modern super-critical airfoils, jet aircraft typically would cruise at or below the critical Mach number, the indicated speed at which local flow over some part of the aircraft, usually the upper surfaces of the wings, reached the speed of sound.

With subsonic local flow over the wings, flying at a constant, optimum angle of attack would yield the best lift-to-drag performance throughout a wide range of cruising altitudes. If, for instance, a first-generation Falcon Jet or Hawker were flown at an optimum angle of attack, it would be possible to eke out more miles per pound of jet fuel than if it were flown at a constant indicated Mach number. (See sidebar.)

In contrast, virtually all current-generation civil jets have supercritical airfoils or semi-supercritical airfoils. This means that the airfoil is designed to operate efficiently with local airflow greater than Mach 1 over a large portion of the wing chord. The wing actually produces more overall lift and lower drag than it would with subsonic flow.

Supercritical airfoils still are most efficient at the best lift-to-drag ratio, as are subsonic airfoils. But the optimum cruise speed is a function of both Mach number and AoA. Flying the aircraft at the optimum Mach number for fuel efficiency thus causes AoA to decrease as aircraft weight decreases. Flying at a constant angle of attack would cost range. Maximum range performance also depends on the thrust output and specific fuel consumption of the engines.

Boeing engineers point out that adjusting cruise speed for winds aloft is more critical to maximum specific range than flying constant AoA. Pilots are advised to fly faster into a headwind and slower with a tailwind to squeeze out optimum range, as shown on the specific range predictions programmed into a full-function FMS.

While cruising at higher Mach numbers increases lift up to some point where drag rises sharply, it also reduces the absolute AoA at which stall occurs. However, there’s usually a 40+ kt. spread between cruise speed and stall warning in modern jets.

That’s all fine for normal cruise. But what about high-altitude upsets? FlightSafety International instructor Mark Scott is fond of saying that integrated glass cockpits have caused pilots to develop instrument stare patterns rather than instrument scan patterns. They tend to fixate on the PFD rather than having to actively monitor the six-pack of conventional instruments. If both PFDs become inoperative, as in the case of AF447, attitude reference, stall margin indication, airspeed, altitude and vertical speed vanish. Pilots must revert to using small emergency instruments or scanning a diminutive integrated standby instrument. AoA awareness information is denied to them, unless the aircraft has a separate angle-of-attack instrument. But if Mach corrections aren’t provided to the AoA system, its usefulness is severely degraded.

Startle factor has the potential to cause pilots to make rash control inputs and thrust changes in the event that the big screens go black. Some potential causes of high-altitude upset can be anticipated, including flight through weather fronts, jet streams and mountain wave, along with pronounced temperature aloft changes, towering cumulus, high-altitude icing and passing through the intertropical convergence zone.

Yet, AoA awareness still is critical during a high-altitude upset, according to the FAA and EASA. The BEA notes that pilots of highly automated aircraft “generally just undertake” flight path and systems monitoring because of the performance and overall reliability of their aircraft, focusing on navigation and fuel management. They’re not necessarily aware of angle-of-attack margins. And they’re not prepared for high-altitude upset recovery.

If the PFD isn’t available, it’s critical to make the transition to the pitch attitude reference on the emergency gyro or integrated standby instrument without delay. Most business aircraft cruise at 2-deg. to 3-deg. nose-up pitch attitude. It’s important to know cruise power settings so that thrust can be maintained or slightly increased to hold altitude. If the aircraft does have an independent AoA indicating system, it can be a useful cross-check to holding target pitch attitude during cruise, assuming pitch and thrust are stable.

If the aircraft does stall inadvertently, it’s essential to reduce pitch attitude smartly, sacrificing altitude for airspeed. During the recovery, it’s also important to keep in mind the considerably lower stalling AoA at typical high cruise altitudes than at low altitudes. The load factor available to recover from a nose-down attitude may be as low as 1.3 Gs.

Bottom line? Angle-of-attack awareness is key to risk management during all phases of flight. It’s critical during low-altitude stall recovery and wind-shear escape maneuvers. We at BCA also believe it’s valuable for flying the appropriate Vref speed, but we recognize that minimum control speed and tail strike prevention, among other factors, must be considered when computing Vref. So, we fly the published AFM Vref speeds instead of AoA, unless the manufacturer otherwise advises.

The optimum aerodynamic lift-to-drag ratio in a modern jet depends both on Mach number and AoA, among other variables. Extracting maximum specific range also depends upon engine thrust output and fuel consumption characteristics.

A stand-alone AoA indicator can be a valuable addition to the cockpit as a backup for Mach and airspeed indications in case of air data system failures. If the gauge is normalized for Mach effect and AoA rate of change, it also has potential to be a valuable stall recovery tool at altitude, assuming pilots are properly trained in its use. But Mach compensation is unlikely to be available in the event of air data system failure.

Thus, controlling angle-of-attack in most jets during high-altitude cruise relies mainly on indirect indications, including pitch attitude, rate of pitch attitude change, airspeed and Mach, plus altitude. AoA awareness is essential in all phases of flight, but it complements reliance on traditional primary flight instruments.

Originally published August 25, 2016

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Re: LCA Tejas: News and Discussions

Postby Dileep » 27 Sep 2016 22:46

Some updates:

1. The High Speed Taxi Trial of SP3 was done yesterday
2. First flight was supposed to happen today, but some 'clearance' was not given, so apparently it didn't happen.
3. Production has picked up speed.
4. IAF has apparently developed a fan base for the bird. In one of the recent reports, they ostensibly said to the effect that the maintainability is not as worse as they thought. The pilots seems to love it, and the airmen are also happy about it.
5. Two SPs were taken to Hindan for the IAF Day. Not much involvement from ADA. Two LSPs are doing weapons trials somewhere in the deserts.
6. The IFR probe integration is almost complete. So is the gun integration.

And yes.. I flew the simulator!!! :) :) :)

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Re: LCA Tejas: News and Discussions

Postby suryag » 27 Sep 2016 22:49

You lucky dawg!!!!

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Re: LCA Tejas: News and Discussions

Postby Sid » 27 Sep 2016 22:53

Dileep wrote:.........................

And yes.. I flew the simulator!!! :) :) :)


mugambo kush hua :mrgreen:

But are these simulators delivered to IAF as well or still with ADA?

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Re: LCA Tejas: News and Discussions

Postby Kartik » 27 Sep 2016 22:57

thanks Dileep for the updates!

IFR probe integration is almost complete? Which LSP will it be fitted to and has it been fitted already? When do flight trials begin?

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Re: LCA Tejas: News and Discussions

Postby ramana » 27 Sep 2016 23:15

Dileep, Tells us more at about the gun integration.

What were the g levels? Did they shock mount the packages? There was concern that they needed to move the packages around.

What was the grouping of the shots? 1 m or less at what distance.

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Re: LCA Tejas: News and Discussions

Postby maitya » 27 Sep 2016 23:46

Kartik wrote:thanks Dileep for the updates!

IFR probe integration is almost complete? Which LSP will it be fitted to and has it been fitted already? When do flight trials begin?

LSP-8

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Re: LCA Tejas: News and Discussions

Postby Bhaskar_T » 28 Sep 2016 00:04

Dileep wrote:Some updates:

1. The High Speed Taxi Trial of SP3 was done yesterday
2. First flight was supposed to happen today, but some 'clearance' was not given, so apparently it didn't happen.
3. Production has picked up speed.
4. IAF has apparently developed a fan base for the bird. In one of the recent reports, they ostensibly said to the effect that the maintainability is not as worse as they thought. The pilots seems to love it, and the airmen are also happy about it.
5. Two SPs were taken to Hindan for the IAF Day. Not much involvement from ADA. Two LSPs are doing weapons trials somewhere in the deserts.
6. The IFR probe integration is almost complete. So is the gun integration.

And yes.. I flew the simulator!!! :) :) :)


Dileep - Many thanks for the updates.

SP3 Delivery - So, after the first flight, what more steps are involved before a formal hand-over is made to IAF? Does SP3 comes with its own user-manual?

Paced-Production - Is it likely that SP4 can be also delivered this year? It will be a record for HAL, from LCA perspective that 3 LCA's are delivered in a single year.

Cobham radome - Any updates on this?
Last edited by Bhaskar_T on 28 Sep 2016 00:13, edited 1 time in total.

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Re: LCA Tejas: News and Discussions

Postby Khalsa » 28 Sep 2016 00:10

Thanks Dileeep.

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Re: LCA Tejas: News and Discussions

Postby JayS » 28 Sep 2016 02:18

Bhaskar_T wrote:SP3 Delivery - So, after the first flight, what more steps are involved before a formal hand-over is made to IAF?


3 flights before handover, as mentioned in some report somewhere. They must be having a standard check list for checking/calibrating all the parameters/instruments/Functionalities etc in various flight regimes.

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Re: LCA Tejas: News and Discussions

Postby Lalmohan » 28 Sep 2016 03:04

er... there is usually a HUGE testing manual... (hint... metal engineering invented these taknikis before software wallahs!) :-)

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Re: LCA Tejas: News and Discussions

Postby Cybaru » 28 Sep 2016 03:41

Dileep wrote:3. Production has picked up speed.
6. The IFR probe integration is almost complete. So is the gun integration.

And yes.. I flew the simulator!!! :) :) :)


Dang brother, that is wonderful news! Can you tell us any more about how the production has picked up? Any tid bits on MK-2?

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Re: LCA Tejas: News and Discussions

Postby Marten » 28 Sep 2016 06:33

Congratulations and thanks Dileep saar. Production picking up is the best news. IAF would come around some day.

Around 4pm yesterday there were two aircrafts flying close to each other. Had assumed one was SP3 and the other a chase aircraft.
PS: Shall email.

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Re: LCA Tejas: News and Discussions

Postby Dileep » 28 Sep 2016 07:30

IFR Probe goes into LSP8. I saw the plane up close. They are now re-settling the stuff that is disturbed by it. The probe itself was NOT left fitted on the body, so I didn't see it. My contact is with Avionics, so he doesn't exactly know the details.

The density of cables/connections within the body is unbelievable. It already breaks my head how we are gonna put fiber through the jumble.

I think they just started gun integration. There was no gun in sight near that plane (I think LSP2 or 3). I don't know the details, since, once again, I know only the avionics folks.

We left the hangar complex around 4:00pm, so don't know if the flight happened or not. Was inside the cold dark places (where yindoos play with the sky gods) after that, till late.

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Re: LCA Tejas: News and Discussions

Postby shiv » 28 Sep 2016 08:46

Dileep wrote:4. IAF has apparently developed a fan base for the bird. In one of the recent reports, they ostensibly said to the effect that the maintainability is not as worse as they thought. The pilots seems to love it, and the airmen are also happy about it.

The HF 24 again was developed for Indians and had a lot of great qualities and was loved by those who flew her. OT, but:
http://i1116.photobucket.com/albums/k56 ... 3iu6qk.jpg
http://i1116.photobucket.com/albums/k56 ... xc9aav.jpg

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Re: LCA Tejas: News and Discussions

Postby saje » 28 Sep 2016 09:02

Just saw LCA making very low pass over hosa road area, near central jail. SP3?

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Re: LCA Tejas: News and Discussions

Postby GShankar » 28 Sep 2016 09:38

Dileep wrote:IFR Probe goes into LSP8. I saw the plane up close. They are now re-settling the stuff that is disturbed by it. The probe itself was NOT left fitted on the body, so I didn't see it. My contact is with Avionics, so he doesn't exactly know the details.

The density of cables/connections within the body is unbelievable. It already breaks my head how we are gonna put fiber through the jumble.

I think they just started gun integration. There was no gun in sight near that plane (I think LSP2 or 3). I don't know the details, since, once again, I know only the avionics folks.

We left the hangar complex around 4:00pm, so don't know if the flight happened or not. Was inside the cold dark places (where yindoos play with the sky gods) after that, till late.


Additional information from a "known person"

Gun (GSh-23) is integrated and in ground trials, it fires around 250 rounds per minute and is very close to be cleared for flight trials




PS:It is 25 and not 250. :mrgreen:

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Re: LCA Tejas: News and Discussions

Postby uddu » 28 Sep 2016 09:59

There is an old video of the same. Posted in Feb 2015 before of the ground test.

Waiting for the next one showing the same in flight. :)

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Re: LCA Tejas: News and Discussions

Postby Bhaskar_T » 28 Sep 2016 10:52

Tarmak (Anantha Krishnan) tweets Tejas-SP3 maiden flight.

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Re: LCA Tejas: News and Discussions

Postby Singha » 28 Sep 2016 10:53

from your note, sounds like IFR was not part of the requirements doc even in 2000 when TD1 was flying and last pieces of design changes for the next batch were being done like side air intake spring loaded for more airflow, APU smoothened intake at base of vertical tail ...

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Re: LCA Tejas: News and Discussions

Postby Marten_b » 28 Sep 2016 13:41

AOA - Been three hours since the SP3 first flight and not a peep from Jingos?
Jago Jingos Jago!

Hope to see Sp4-6 come through by March 2017. IAF expectations are high, and any slip-ups would basically support the demands for another MRCA instead of the Tejas. Apparently the Capex budget for IAF will be fuelled by Fairy Dust (and a 32% GST rate to support 232 off MRCAs, be they under Make in India or elsewhere).

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Re: LCA Tejas: News and Discussions

Postby JayS » 28 Sep 2016 14:15

GShankar wrote:Additional information from a "known person"

Gun (GSh-23) is integrated and in ground trials, it fires around 250 rounds per minute and is very close to be cleared for flight trials
PS:It is 25 and not 250. :mrgreen:


250 per min is too slow a rate. Even 25rounds per sec is on lower side.


tsarkar wrote:Following is an AW&ST article on AoA, in context of our discussion here

http://aviationweek.com/business-aviati ... -indicator


X-31 was lost due to similar cause - ice formation on pitot tube - pilot couldn't gauge situation - aircraft stalled.

The other day I was reading some article where it was said that with every new generation there is a loss of basic piloting skills, because FCS is trivializing a lot of things. I see this AoA thing connected with that.


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