LCA News and Discussions

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suryag
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Re: LCA News and Discussions

Post by suryag »

[wetdreams] was it PV2?, it seems to have flown after a long time (after two months)[/wetdreams]
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Re: LCA News and Discussions

Post by nachiket »

ketan.sojitra wrote: Yesterday around 2 pm show LCA with IFR probe. Are there any of them LSP or PV flying with IFR attached? Or was it LSP 6/7
Are you sure it was an LCA? Some fighter jets are difficult to distinguish from afar. A M2000 for e.g. can easily be confused with an LCA if you catch only a quick glimpse or if it's too far away. A M2000 would be a rare sight in BLR though.
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Re: LCA News and Discussions

Post by suryag »

SBTF update from tarmak
While the SBTF work is probably ahead of the schedule, sources say that the eagerly-awaited first flight of NLCA (Naval Prototype NP-1) is on course. The platform is said to have undergone a trial for nose-wheel checks (70 km) on Valentine’s Day, while a LSTT (low-speed taxi trial) at a possible max speed of 140 km/hour is scheduled for February 18. This would be followed by a HSTT (high-speed taxi trial) at a maximum speed of 200-200 km/hour and then the subsequent first flight.
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Re: LCA News and Discussions

Post by Singha »

in 7 yrs the only time I have never seen M2K in HAL. did see MKI few times flying into HAL for events like AI09.
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Re: LCA News and Discussions

Post by merlin »

So lets see what is the sequence of events for an LCA new bird to fly

1. Fabrication
2. Roll out
3. SCT, vibration and other tests
4. Engine Ground Run (EGR)
5. Nose wheel checks (at 70 kmph per above report)
6. Low speed taxi trials (at 140 kmph per above report)
7. High speed taxi trials (at 200-220 kmph per above report)
8. Rotation tests?
9. First flight
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Re: LCA News and Discussions

Post by George J »

Singha wrote:in 7 yrs the only time I have never seen M2K in HAL............
"They" don't fly, they are for some sort of "research purposes" onlee.
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Re: LCA News and Discussions

Post by suryag »

Flight test update

LCA-Tejas has completed 1780 Test Flights successfully. (17-Feb-2012).
(TD1-233,TD2-305,PV1-242,PV2-212,PV3-330,LSP1-68,LSP2-198,PV5-36,LSP3-46,LSP4-45,LSP5-65)

from

LCA-Tejas has completed 1779 Test Flights successfully. (16-Feb-2012).
(TD1-233,TD2-305,PV1-242,PV2-212,PV3-330,LSP1-67,LSP2-198,PV5-36,LSP3-46,LSP4-45,LSP5-65)

Someday i would like to know what group of aircraft was used for what kind of flight testing
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Re: LCA News and Discussions

Post by Vikram W »

So Boeing is planning to make about 10 Dreamliners a month by Q4 2013, scaling up from its current 2.5 a month . Meanwhile, HAL is going to make about 10 a year ramping up from Zero all of last year.... just saying.

http://online.wsj.com/article/BT-CO-201 ... 01263.html
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Re: LCA News and Discussions

Post by Vashishtha »

So Boeing is planning to make about 10 Dreamliners a month by Q4 2013, scaling up from its current 2.5 a month . Meanwhile, HAL is going to make about 10 a year ramping up from Zero all of last year.... just saying.

http://online.wsj.com/article/BT-CO-201 ... 01263.html
you shouldn't have :)
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Re: LCA News and Discussions

Post by member_22866 »

Cain Marko wrote:
Very, very interesting Ketan, welcome to the board - you come bearing good/interesting news. Can any jingos with inside clearances to sensitive areas such as golf courses or roof tops confirm this development?

CM
Thanks CM
nachiket wrote: Are you sure it was an LCA? Some fighter jets are difficult to distinguish from afar. A M2000 for e.g. can easily be confused with an LCA if you catch only a quick glimpse or if it's too far away. A M2000 would be a rare sight in BLR though.
I don't think it was M2000, thought i could only get a gimps of it while riding. I ride home for the lunch as it is just about a KM from working place.

As for the LCA? or what i show was coming in to landing from Marthahalli end. May be they have upgraded one of the LSP which are flying.
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Re: LCA News and Discussions

Post by pragnya »

Cain Marko wrote:
ketan.sojitra wrote:Hi All,
This is my first post although I have been lurking on BR for almost 11 years.
Am SDRE IT guy from Bangalore.

Yesterday around 2 pm show LCA with IFR probe. Are there any of them LSP or PV flying with IFR attached? Or was it LSP 6/7
Very, very interesting Ketan, welcome to the board - you come bearing good/interesting news. Can any jingos with inside clearances to sensitive areas such as golf courses or roof tops confirm this development?

CM
CM

Kakarat's photo of a scan of tejas booklet from AEROINDIA 2011 did show the IFR probe. i won't doubt if it has been carried to it's logical conclusion. so what ketan is saying may actually be true!! :mrgreen:

FWIW take a look at this -

http://www.bharat-rakshak.com/media/Aer ... 1.jpg.html
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Re: LCA News and Discussions

Post by member_22605 »

It was an M2K and not an IFR equipped LCA, the M2Ks are overhauled in HAL overhaul division, so finding one shouldn't be problem at all.
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Re: LCA News and Discussions

Post by merlin »

raghuk wrote:It was an M2K and not an IFR equipped LCA, the M2Ks are overhauled in HAL overhaul division, so finding one shouldn't be problem at all.
An easy way to distinguish an M2K from an LCA is the massive size of the LCA wing compared to its fuselage. M2K's wing does not look as oversized.
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Re: LCA News and Discussions

Post by Kartik »

Vikram W wrote:So Boeing is planning to make about 10 Dreamliners a month by Q4 2013, scaling up from its current 2.5 a month . Meanwhile, HAL is going to make about 10 a year ramping up from Zero all of last year.... just saying.

http://online.wsj.com/article/BT-CO-201 ... 01263.html
Just saying what? Any idea how many firm orders Boeing has for the 787 as compared to the LCA? If Boeing didn't make that many a month, they'd lose a whole bunch of new customers to Airbus' A350, since those customers will not be willing to wait till they get their 787s after 10+ years or so. Boeing replaced the anaemic 767 line with the 787 line since there were almost no orders for the 767 anymore..and then set up another one at its Everett plant just because it has so many orders for the 787..and then it went on to set up another entire 787 factory in South Carolina because even that wasn't enough.

Why would HAL set up a larger assembly line unless they can get firm orders from their one and only customer? If IAF only intends to place orders for 40 Tejas Mk1, HAL will only set up an assembly line for 10.
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Re: LCA News and Discussions

Post by tsarkar »

Kartik wrote:Why would HAL set up a larger assembly line unless they can get firm orders from their one and only customer? If IAF only intends to place orders for 40 Tejas Mk1, HAL will only set up an assembly line for 10.
Orders cannot be given until the design meets basic performance parameters.

In DRDO's own words http://www.drdo.gov.in/drdo/pub/dss/200 ... EMILAC.pdf
It is seen that most of the performance parameters are deviating from the requirements.
The Air brakes in Tejas provided at the rear spinal part of the fuselage to decelerate aircraft at higher speeds. Due to this rear location in addition to the deceleration it gives an uncommanded pitch up and directional stability reduction. Various improvement methods like perforated airbrake, updation of aero data set and fine tuning of control law gains were tried. Still the problem is not rectified completely.
Tejas airbrakes http://www.bharat-rakshak.com/media/Aer ... e.jpg.html Sukhoi airbrakes http://www.flickr.com/photos/vishwak/5436297107/ mounted close to CoG, so no such moment arm acting on the aircraft. Mirage 2000 airbrakes are mounted on wing http://rafaleair.free.fr/photo2/mirage%202000-5%20F.jpg close to CoG.

Common sense dictates such parts be close to CoG to minimize uncommanded movements. However, for reasons best known to designers, they didn’t. Simulation/Testing should have revealed this during design, but again, this went ahead.

F-16 has rear brakes, but they split open equalizing the force unlike the upward-only Tejas http://pafwallpapers.com/blog/wp-conten ... arrows.jpg

Solution
A study taken up to utilize the main landing gear follow up door as an airbrake.
So we’ll see a plane that’ll keep opening its MLG doors in flight.
One of the major out come of sea level trial of Tejas is that the drag of the aircraft is high such that the aircraft could not reach the supersonic Mach number at sea level.
Solution
Nose cone extension using a Plug.
In Mk2
Trailing Edge Extension (TEC)
Now this is interesting. Many BR members on seeing the abrupt training edge had commented that it would be draggy. http://imageshack.us/photo/my-images/88 ... 01is2.jpg/
Common Sense that airflow split at wing root leading edge should be enabled to rejoin at the wing root trailing edge.
From the Fig. 12 it is seen that there is a sudden variation in cross sectional area at the rear end of the fuselage also. This can be minimized by the modification in the trailing edge using TEC. Fig. 15 and Fig. 16 shows the rear fuselage before and after modification.
Again, why didn’t this come up during initial design/testing.
The fighter variant of Tejas is not meeting the STR requirement of ASR.
Atleast until 2009, there was no solution in place.
A detailed study to implement Levcon in fighter and identification of other design constraints is under progress.
IAF has valid reasons to describe Tejas as a deformed Cheetah. Despite that 40 planes have been ordered, that is 5.5% of its authorized fighter force. FWIW, I doubt IAF will ever deploy Mk 1 in air to air combat, risking the lives of the pilot without performance requirements being met. Also, with further design changes, manufacturing will be impacted.
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Re: LCA News and Discussions

Post by suryag »

Tsarkarji we have done this so many times. Supporters of the forces insist everything should be fine before they are inducted, supporters of the tejas say, the forces inducted far inferior equipment in the past. I am not even an aviation noob, but high landing speed of MIG21 was/is considered hazardous, so why didnt the famed MIG bureau consider this while designing ? This aspect of MIG21 is taken as a characteristic of the aircraft and tactics built around it. Similarly there was something with the JAG

In similar vein cant the IAF accept it and make it better rather than coming up with newtonian statements like "it is a deformed cheetah" ? Why wasnt the IAF involved in providing design inputs during the 1990-93 timeframe ? I am sure they have a wealth of experience in operating aircraft a simple thing(the CoG thing) that could strike you(no offence intended) would have struck any iaf pilot Why didnt they communicate it then? Both sides are to be blamed hope AMCA charts a different course
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Re: LCA News and Discussions

Post by Nick_S »

Tsarkarji, thank you for the informative post.

The linked DRDO article was very interesting. By any chance, if you have more links to any other similar articles on LCA/HJT-36/Dhurv could you please share them? I would like to go through them.

Thanks.
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Re: LCA News and Discussions

Post by Kartik »

tsarkar wrote:Orders cannot be given until the design meets basic performance parameters.

In DRDO's own words http://www.drdo.gov.in/drdo/pub/dss/200 ... EMILAC.pdf
It is seen that most of the performance parameters are deviating from the requirements.
The Air brakes in Tejas provided at the rear spinal part of the fuselage to decelerate aircraft at higher speeds. Due to this rear location in addition to the deceleration it gives an uncommanded pitch up and directional stability reduction. Various improvement methods like perforated airbrake, updation of aero data set and fine tuning of control law gains were tried. Still the problem is not rectified completely.
I was talking about if from HAL's point of view. They won't be able to set up a larger assembly line without a larger order. As for whether or not the IAF can or cannot place a larger order for the Tejas, I don't subscribe to the theory that a few teething troubles should mean that they show dampened enthusiasm for the aircraft itself.

The pitch up issue is not a make or break type issue. The Typhoon had a major transonic pitch-up issue as late as 2002 that was solved with a major FCS update. Typhoon transonic pitch-up issue. And yet, did that mean that the Eurofighter nations said, hey lets just order a token 40 odd Eurofighter's each?

IAF has valid reasons to describe Tejas as a deformed Cheetah. Despite that 40 planes have been ordered, that is 5.5% of its authorized fighter force. FWIW, I doubt IAF will ever deploy Mk 1 in air to air combat, risking the lives of the pilot without performance requirements being met. Also, with further design changes, manufacturing will be impacted.
Yes, why deploy a Tejas Mk1, when you have MiG-21s with even worse aerodynamic flaws that an inattentive pilot would push over the limit in the blink of an eye.
Last edited by Kartik on 19 Feb 2012 13:41, edited 1 time in total.
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Re: LCA News and Discussions

Post by Vikram W »

Kartik, I was juxtaposing HAL manufacturing speeds vis-a-vis other companies ( making a much larger and complex plane). HAL bosses claimed they would be rolling out one fighter a month starting September 2010. So far all we have had is missed deadlines. You can all jump in and tell me that IAF has not given firm orders , but as the poster above mentioned, it's more of a chicken and egg story. IAF has committed to higher numbers, but ASRs are still not met and delivery deadlines have slipped to a point that not a single new plane flew in 2011.
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Re: LCA News and Discussions

Post by suryag »

Vikram W ji you havent visited the raffy thread i suppose(link posted by kartik ji)
rafale flight test

From the above link
To date, about 70 Rafales have been delivered, with a current production rate of 12 a year.
so either rafale is not as complex as tejas or Dassault is as inept as HAL
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Re: LCA News and Discussions

Post by sudeepj »

Regardless of how the IAF characterizes the LCA, if India pursues her own strategic goals - not in consonance with the hyper power blocks, the deformed Cheetah may be the only cat in Indian service with any claws and fangs! Others may simply be grounded!
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Re: LCA News and Discussions

Post by SaiK »

Relying on french technology against russian one, does not lead to independence rather only transferring dependence to another country. The problem is DRDO's failure and GoI support to all indigenous efforts for Kaveri, which is core for any dependency relationship. No matter, how successful LCA is, if Kaveri-snecma is all it gets, then we are totally dependent on french for executions. All it takes is sarkozy or a future fr president making a statement.

Kaveri++ standing by itself.. charting its own life time and establishing for our services is vital for LCA's long term goals. This $2b deal with fr needs to be reviewed by strategists, and work with already dependent nations to reduce dependency on long term basis. The short term dependency is manageable, for us, but not long term. Fr is our next gen russia!
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Re: LCA News and Discussions

Post by Kartik »

tsarkar wrote:
The Air brakes in Tejas provided at the rear spinal part of the fuselage to decelerate aircraft at higher speeds. Due to this rear location in addition to the deceleration it gives an uncommanded pitch up and directional stability reduction. Various improvement methods like perforated airbrake, updation of aero data set and fine tuning of control law gains were tried. Still the problem is not rectified completely.
Tejas airbrakes http://www.bharat-rakshak.com/media/Aer ... e.jpg.html Sukhoi airbrakes http://www.flickr.com/photos/vishwak/5436297107/ mounted close to CoG, so no such moment arm acting on the aircraft. Mirage 2000 airbrakes are mounted on wing http://rafaleair.free.fr/photo2/mirage%202000-5%20F.jpg close to CoG.

Common sense dictates such parts be close to CoG to minimize uncommanded movements. However, for reasons best known to designers, they didn’t. Simulation/Testing should have revealed this during design, but again, this went ahead.

F-16 has rear brakes, but they split open equalizing the force unlike the upward-only Tejas http://pafwallpapers.com/blog/wp-conten ... arrows.jpg
Even the Hawk had a single airbrake that was located in front of its ventral fins. Lack of common sense on the part of Hawker Siddeley perhaps?

Image

Image

Even the Tornado's airbrakes are located right at the end, just under the fin

Image

And look at where the F/A-18's airbrakes are located..
Image
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Re: LCA News and Discussions

Post by Reddy »

Kartik wrote: Even the Hawk had a single airbrake that was located in front of its ventral fins. Lack of common sense on the part of Hawker Siddeley perhaps?

Even the Tornado's airbrakes are located right at the end, just under the fin

And look at where the F/A-18's airbrakes are located..
I am no aero expert.
Is the problem with uncommanded pitch-up in LCA is because of delta wing?
I ask because, all other aircraft examples Kartik took can compensate for pitch up by the elevators. Since LCA's air-breaks appear to be dang on delta wing Aileron are they more of a problem?
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Re: LCA News and Discussions

Post by Raman »

IIRC, even the Gnat used the MLG doors as airbrakes. I always thought it was a very clever idea and wonder why more aircraft don't use this technique - probably saves weight as well.
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Re: LCA News and Discussions

Post by Indranil »

Raman wrote:IIRC, even the Gnat used the MLG doors as airbrakes. I always thought it was a very clever idea and wonder why more aircraft don't use this technique - probably saves weight as well.
That is exactly my thought!

The only reason I could think of is that while coming in to land the aircraft has lower decelerating power without dedicated airbrakes.
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Re: LCA News and Discussions

Post by Indranil »

Reddy wrote:
Kartik wrote: Even the Hawk had a single airbrake that was located in front of its ventral fins. Lack of common sense on the part of Hawker Siddeley perhaps?

Even the Tornado's airbrakes are located right at the end, just under the fin

And look at where the F/A-18's airbrakes are located..
I am no aero expert.
Is the problem with uncommanded pitch-up in LCA is because of delta wing?
I ask because, all other aircraft examples Kartik took can compensate for pitch up by the elevators. Since LCA's air-breaks appear to be dang on delta wing Aileron are they more of a problem?
No it is just simple physics ... if you apply a force not passing through CG, it would provide a moment, delta wing or not.
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Re: LCA News and Discussions

Post by keshavchandra »

the gear box of India’s Light Combat Aircraft (LCA), Tejas, was tested in the CATH chambers.The building contains Combined Altitude, Temperature and Humidity (CATH) chambers, thermal shock chambers, dust chambers, corrosion chambers, and so on, where the various parts of radars are tested thoroughly before the systems are deployed in the field. The thermal shock chamber has three compartments. In the “cold” compartment, the temperature ranges from -700 Celsius to +800 C and in the hot cell, it ranges from 00 C to 2000 C. The third compartment has ambient temperature. The airborne radar systems are tested in these temperatures because when an aircraft climbs to an altitude of 40,000 feet (12,000 metres), the transition time from the ambient temperature to freezing cold is only 10 minutes. The airborne radar systems should withstand these thermal shocks. :)
Combined Altitude, Temperature and Humidity (CATH) chambers
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Re: LCA News and Discussions

Post by Kailash »

keshavchandra wrote:temperature ranges from -700 Celsius to +800 C and in the hot cell, it ranges from 00 C to 2000 C
I see from the link that the last zero is a symbol for degrees.. just for a moment thought someone breached absolute zero :lol:
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Re: LCA News and Discussions

Post by keshavchandra »

Kailash wrote:
keshavchandra wrote:temperature ranges from -700 Celsius to +800 C and in the hot cell, it ranges from 00 C to 2000 C
I see from the link that the last zero is a symbol for degrees.. just for a moment thought someone breached absolute zero :lol:
By this I think they may get the melting point of whole airframe. :rotfl:
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Re: LCA News and Discussions

Post by Kersi D »

Vikram W wrote:So Boeing is planning to make about 10 Dreamliners a month by Q4 2013, scaling up from its current 2.5 a month . Meanwhile, HAL is going to make about 10 a year ramping up from Zero all of last year.... just saying.

http://online.wsj.com/article/BT-CO-201 ... 01263.html
I conclude that Boeing is slightly better than HAL. :(( :(( :((
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Re: LCA News and Discussions

Post by JTull »

keshavchandra wrote:the gear box of India’s Light Combat Aircraft (LCA), Tejas, was tested in the CATH chambers.The building contains Combined Altitude, Temperature and Humidity (CATH) chambers, thermal shock chambers, dust chambers, corrosion chambers, and so on, where the various parts of radars are tested thoroughly before the systems are deployed in the field. The thermal shock chamber has three compartments. In the “cold” compartment, the temperature ranges from -700 Celsius :shock: to +800 C and in the hot cell, it ranges from 00 C to 2000 C. The third compartment has ambient temperature. The airborne radar systems are tested in these temperatures because when an aircraft climbs to an altitude of 40,000 feet (12,000 metres), the transition time from the ambient temperature to freezing cold is only 10 minutes. The airborne radar systems should withstand these thermal shocks. :)
Combined Altitude, Temperature and Humidity (CATH) chambers
Below Aboslute zero? :rotfl:
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Re: LCA News and Discussions

Post by Neela »

Kersi D wrote:
Vikram W wrote:So Boeing is planning to make about 10 Dreamliners a month by Q4 2013, scaling up from its current 2.5 a month . Meanwhile, HAL is going to make about 10 a year ramping up from Zero all of last year.... just saying.
http://online.wsj.com/article/BT-CO-201 ... 01263.html
I conclude that Boeing is slightly better than HAL. :(( :(( :((
Dear Kersi D-ji,
Please enlighten HAL on how to manufacture aircraft with your expertise. And how to ramp up production.
And give a brief outline here on how HAL can do better .


Maybe last time around, when you had criticism for HAL ( and an overwhelming urge to misuse and rape the poor smileys ) , you were not given a chance proper.
This time around, we will ignore your fondling of smileys BUT please enlighten us and stupid folks at HAL!
All ears !
Go !
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Re: LCA News and Discussions

Post by keshavchandra »

JTull wrote:
keshavchandra wrote:the gear box of India’s Light Combat Aircraft (LCA), Tejas, was tested in the CATH chambers.The building contains Combined Altitude, Temperature and Humidity (CATH) chambers, thermal shock chambers, dust chambers, corrosion chambers, and so on, where the various parts of radars are tested thoroughly before the systems are deployed in the field. The thermal shock chamber has three compartments. In the “cold” compartment, the temperature ranges from -700 Celsius :shock: to +800 C and in the hot cell, it ranges from 00 C to 2000 C. The third compartment has ambient temperature. The airborne radar systems are tested in these temperatures because when an aircraft climbs to an altitude of 40,000 feet (12,000 metres), the transition time from the ambient temperature to freezing cold is only 10 minutes. The airborne radar systems should withstand these thermal shocks. :)
Combined Altitude, Temperature and Humidity (CATH) chambers
Below Aboslute zero? :rotfl:
I think it is the article editing issue or they are experimenting the whole gear box in Liquid nitrogen.. :-?
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Re: LCA News and Discussions

Post by krishnan »

.
Last edited by krishnan on 21 Feb 2012 06:28, edited 1 time in total.
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Re: LCA News and Discussions

Post by Rahul M »

someone from BRF reads idrw too.
we are not amused !
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Re: LCA News and Discussions

Post by suryag »

Contract soon for Derby
Israeli Derby to be Prime BVRAAM for Tejas MK-1

Interesting things in the article
Tejas MK-1 which has a hybrid radar based on Israeli Elta’s 2032 radar and Indian technology seems to be the prime reason behind the selection, although DRDO is working on developing a home grown Air to Air Missile under Astra Project, but it seems that missile will take time to carry out all its test parameters and currently has been integrated with Sukhoi su 30 MKI aircrafts only and will also see first firing of the missile in mid of 2012.
So Astra might be fired from the Rambha by mid 2013(given we have to add minimum 1 year to what DRDO says)
Sources close to idrw.org also have told us that Python-5 might be also be considered for Tejas MK-1 for meeting short range Air to Air missile ,Russian R-73 was successfully had been integrated with Tejas MK-1, but it seems some issues might have surfaced due to which air force is also interested in Israeli Python-5 .

FWIW good part is that R-73 has been successfully integrated, worrisome part is force is not happy with it on tejas and now wants python-5, hope this is not another reason to delay induction. Also curious why wasnt R-77 selected for the BVRAAM
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Re: LCA News and Discussions

Post by karan_mc »

Derby BVRAAM is the natural choice , since without BVR missile integration into Tejas , IAF will not accept them in to forces and will not grant FOC which is scheduled for 2013 .

R-73 was first test fired from Tejas in 2007 , Good five years back ,either they want a new Generation missile like Python-5 or are not happy with the test results achieved with R-73 , if i am not wrong both have similar range .
Gurneesh
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Location: Troposphere

Re: LCA News and Discussions

Post by Gurneesh »

Kartik wrote:
Even the Hawk had a single airbrake that was located in front of its ventral fins. Lack of common sense on the part of Hawker Siddeley perhaps?

Even the Tornado's airbrakes are located right at the end, just under the fin



And look at where the F/A-18's airbrakes are located..
Just a thought, all the a/c's mentioned here have tails, while LCA is tailless. Tails should help counter any asymmetric moment applied by air brakes.

M2000 has air brakes on the wings i guess.
Indranil
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Re: LCA News and Discussions

Post by Indranil »

Gurneesh wrote:
Kartik wrote:
Even the Hawk had a single airbrake that was located in front of its ventral fins. Lack of common sense on the part of Hawker Siddeley perhaps?

Even the Tornado's airbrakes are located right at the end, just under the fin



And look at where the F/A-18's airbrakes are located..
Just a thought, all the a/c's mentioned here have tails, while LCA is tailless. Tails should help counter any asymmetric moment applied by air brakes.

M2000 has air brakes on the wings i guess.
Gurneeshji,

How does it mater if your elevator (pitch control device) is placed as a separate tail or part of the wing? If you can pitch down, you should be able to compensate for the un-commanded pitch-up due to activation of the airbrakes. This was the expectation from the FBW. However, they found out that they cannot completely mitigate this.

Why, even I would love to know the reasons :-). But it is certainly not because the elevators are not arranged as part of the tail. One suspected cause could be that the processing is not fast enough.

This is a callout to a poster here named Rajeev Chandramohan ... He is an expert on controls ... Unfortunately, people here scoffed him off even though he was proven right later ... I hope he reads this and provides his take on this.
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