mattMakes sense for a military aircraft that is not intended for sale to other customers.
Fair comment but;
you would still have to certify the structure and that will cost, as a program manager if your aircraft is meeting the target performance criterion then you would say ok job done lets move onto the MCA. or bring in incremental changes to the weight savings (i.e. risk of not meeting performance goals has been reduced so we can relax and slowly improve the aircraft).
Secondly if the aircraft met its performance goals and your armed forces were in desperate need for it to bolster up squadron strength, and were having to pay out 10 billion dollars for a stop gap, you would not turn around to them as say, “well look we have achieved what we set out to but would you nice chaps mind waiting another few years because we dont want to give this to you yet”.
mattok do not understand the issue here….
If your design target is 5500 Kgs and all your performance calculations are based on that weight but your aircraft actually makes it 6500kg you are over weight it does not matter if other aircraft weight the same as yours.
If the LCA structural weight increase is due to a lack of confidence in the design or stressing phase:
2 possibilities exist,
1) If the structure was produced as designed then the fact that the structure is heavier (i.e. you have more plies than you really need) should mean that your would be able to take up higher load factors than design. Unless you have actually just put on dead weight to the structure in the initial design phase. i.e. trying to increase through thickness strength by having more inplane plies :S
2) Inversely if your production process cannot produce parts without defects then you have to restrict the loading the aircraft will see (i.e. reduced confidence level in structure). and you end up requiring the heavier structure just to cope with the defects.
From my undestanding using material from an INTERNATIONAL supplier there should be little lack of confidence in the material.
The report above says that the LCA is over weight and that the IAF can only afford to go with a compromised design due to the availability of helmet mounted targetting.
Equipment-fit LSP-wise is in the final standard of preparation for the IAF. All the sensors, communication equipment and weapons required for the current Initial Operational Clearance (IOC) are present. Also since we were designing a fighter of this class for the first time, we were very conservative in the design. Especially when it came to structural strength characteristics and this has lead to an increase in weight. Weight optimisation will be undertaken for the Tejas Mk-2 variant to reduce its weight.
Due to the weight growth, there have been certain deviations in the performance parameters. The IAF has validated these deviations to be compensated by advanced weapon systems which were not available in 1985. We will not incorporate any changes in the Mk-1 version as it is ready for production. In the Mk-2 version of Tejas, we expect to see weight savings of around 300 to 500Kg which will come from weight optimisation in the aircraft structures alone.
i.e. the LCA is over weight…. you would not attempt to do a weight saving exercise on a aircraft that had met its performance goals.
mattthe LCA Mk1 is a 9G fighter and was designed from ground up as a 9G fighter. that means all the ultimate load cases are designed by factoring in 9G as the limit load. ok ?
Regarding whether or not it has reached 9G during testing, well that is not clear. Maybe as more information about the program appears in the public domain, that will be cleared up as well.
the fact is that the empty weight of the Tejas Mk1 as it stands TODAY is lower than that of the Gripen C/D. . You won’t question PS Subramanyam’s statement about 6500 kgs at least, will you as you have questioned others in the past who have repeatedly said the same ?
Dont understand your point about the LCA to gripen comparison here however; LCA was designed to have a weight of 5500Kgs or so but has ended up a lot heavier. i.e. its over weight. Does not matter if it is lighter than the gripen.
Also wether through engine issues or structural issues or mixture of both from what is available in public domain on the internet the LCA is restricted to 6/7 gs i.e. below the 9g design limit.
If you take the above into consideration and you if you really want to compare the LCA weight to the Gripens you must compare these facts also.
mattWhat ever it is India and IAF need to get the AKASH to increase coverage. Hopefully atleast the electronics will have been updated and made more jam resistent.
Hopefully India will not be witness to something like the alleged Israeli attack on its neighbours nucleare power plunt up north.
mattThanks Vishnu ! wonderful read !
interesting to note that the Gripen Demo is actually several hundred kgs overweight..some posters made a lot of mockery of the LCA when it was revealed that it was overweight.
Yes you are correct kramer posters like myself do not mock but question the weight issues in the LCA (please note the difference here). Also there is a big difference here Kramer, one aircraft is overweight but will be classed as a 10G fighter and have the ability to supercruise whilst the other cant/wont.
mattThanks Austin ! that is one illuminating interview and we finally have some details on the Tejas Mk2 !
And this particular statement of PS Subramanyam confirms it once and for all that the weight of the Tejas Mk1 is 6500 kgs which is nearly same as the Gripen C/D (6800 kgs empty) and JF-17 (6411 kgs empty)..how the heck is that supposed to be overweight only the critics know.
It can be said to be over weight simply by the virtue that the final weight of the aircraft was above the design weight of the aircraft. Hence it was over its design weight.
Now you could argue that most aircraft that size weight around the same in which case you would have to look at the guys doing the weight estimations and ask them what happened.
On the flip side the fact that the Tejas was no more lighter than its contemporaries makes moot any bombastic claims of Tejas having the most amounts of composites.
But as you would know composite structures will only be lighter than traditional structures if the design team understand them and if the production team can produce defect free structures.
mattIt will be good to see the 500Kg reduction in structural weight. As was hinted by Ether the extra weight of the Tejas wasnt to do with a scope creap by the IAF but due to other issues.
The IAF have been pretty supportive by the sounds of things in accepting limitations on the aircrafts ability to point the nose towards a target. Maybe with the Mk-2 and a loss in weight of 500kg we will see those performance parameters improve.
I did make not of the fact that they are using helmet targetting and hence have been able to make apologies for deficiencies mentioned above no one can be more pragmatic than that.
The materials should be well understood and understood enough by now to give the stress team some confidence.
Still have to wonder if the weight could be further reduced. If the spars are arranged in the LCA as a CAD wireframe i once saw suggests there maybe an opertunity to take out some weight from that region. But again that maybe a different story.
Have to wonder if the ADA/DRDO will try to poke the international material supplier for some new materials to make the most of the Mk2 opertunity and reduce weight as much as possible. I guess they will always be restricted by pragmatic swings and roundabout balances.
matt500 or so twin seat aircraft? Including the Su 30. Hmm. Will they have higher thrust engine than the Russian pakfa? Just to make up for the extra wetted area and greater weight? Will it still be able to supervise?
Would make more sense if IAF mix the 250 with 100 twin seat and rest as single.
Is Russia working on fifth gen interceptor to complement the pakfa.
mattI guess with modern day avionics and ACT you don’t need to worry about having high or low wing loading for any particular mission profile. Would be a shame to see tje Jaguar phase out completely from the world.
mattC-130J Super Hercules:Advantage IAF
“That is when the IAF will gets first look at the aircraft. After flight tests and other trials, the aircraft will be handed over in the first quarter of 2011,” Jack Crisler, director of the C-130J programme, told a group of visiting Indian journalists, adding that the sixth aircraft was scheduled for delivery by the end of 2011.The C-130J primarily performs the tactical portion of an airlift mission. The aircraft is capable of operating from rough, dirt strips and is the prime transport for air dropping troops and equipment into hostile areas.
The flexible design of the Super Hercules enables it to be configured for many different missions, allowing for one aircraft to perform the role of many. Much of the special mission equipment added to the Super Hercules is removable, allowing the aircraft to quickly switch between roles.
To this end, the six C-130Js will primarily be deployed for the operations of the Indian Army’s Special Forces, even as the IAF mulls the purchase of another six aircraft, some of them configured as midair refuellers.
“Some of the other six could well be the MC-130J version,” said Robert A. Lowe, Lockheed Martin’s business development director (Air Mobility), adding that the tankers could refuel both fixed wing and rotary aircraft.
This (MC130) if it goes through the best purchase from the US that the IAF will ever make! that is if the CISMO thing and all other US ITAR type issues and End User Agreements do not get in the way and cause restrictions.
Report could be better written, its confusing and could mislead.
rest of the artical is on India Server…
mattIndia to hand out giant war jet deal by July: air force
NEW DELHI: India, which is racing to upgrade its military, is likely to hand out a 12-billion-dollar contract for 126 fighter jets by July 2011, the country’s air force chief said on Friday.
SNIP________
US-based Lockheed Martin, offering F-16, and Boeing’s F-18 “Superhornet” emerged as the front-runners following the gruelling trials, industry sources have said.
The European Aeronautic Defence and Space Company has offered its Typhoon Eurofighter and French Dassault, which constructs the Mirage, has put forward its Rafale.
Russian manufacturers of the MiG-35 and MiG-29, as well as Sweden’s Saab, which is hawking its Gripen fighter, are also in the running for the biggest fighter jet contract in 16 years.
The contract includes the outright purchase of 18 fighter jets by 2012 with another 108 to be built in India.
India would also have an option to buy 64 more such jets.
Air chief marshall Naik’s announcement came a day after Moscow and New Delhi unveiled plans to co-develop 250-300 advanced stealth fighter jets for military technology-hungry India.
Aviation experts say the 30-ton Russian-designed planes could cost up to 100 million dollars each.
How can the F16 and 18 turn out to suddenly lead the contest? Wonder what industry sources they were?
This will tie up Indias Soveriegnty for many years to come and give it aircraft that are of little or no use to it.
mattSo dont understand, are people argueing that India does not need a AAW system?
In all seriousness? Is that a khate Angoor (sour grapes) syndrome because current Indian Airdefense systems have had a set back and the Spyder system has had to be bought and India has had to go into development with Israel for the MR – SAM or Barak NG to get any type of reputable AAW in its ships?
So because India failed with AAW ships suddenly India does not need something like the Type 45?
Yes and this time i am confused!
mattFailure rates are a fact. That you dont know about it is fairly surprising.
All BM system’s have a certain failure rate determined by both extensive simulation and real world testing. As a rough rule of thumb, you can have around 10 – 20% failures expected in real world conditions, unless the technology is significantly mature and has been proven by many decades of service. The problem in that case is that many of the onboard systems are obsolete, making their maintenance hard, and also the overall performance may not be optimal.
Reasons for failure can be many & even the most predictable peace time processes and methods can end up being short circuited during wartime, posing new challenges.
At any rate, is the reason why countries prefer to have rather decent stocks of ballistic missile systems and rely on multiple methods of delivery, not just aircraft or missiles. There have been several incidents where entire missions had to be scrubbed because of snafus, in maintenance or mission planning.
Note what I am saying about systems– today’s missiles are not just align and shoot ballistic missiles with rudimentary gyros. They are highly sophisticated, software intensive units with many complex subsystems, and many of these systems happen to be on the critical path for overall success. Read page 138.
http://books.google.co.in/books?id=0vfDUNyUZlUC&pg=PT150&dq=ballistic+missile+failure+rates&hl=en
Its always a trade-off at the end of the day, despite all the attempta designers make, i.e. design for simplicity, redundancy etc.
Its all very interesting, but completely avoids the questions asked in my post. Anyways its ok we all do this some times you know when we have late nights etc…
mattWell look its ok your confused you have jumped into a conversation for some reason or other and missed the point.. Its ok we all do this .. anyways please do read the above posts again. 🙂
mattGE built Low pressure turbine blades out of ceramic matrix composites. They already have built liners, shrouds, nozzles with ceramic matrix composites.
So is the compressor the same as a turbine? And what cmc did GE use for its turbine ?
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