LCA news and discussion
Re: LCA news and discussion
@Ravi all I can know is that Tejas had established a 18 degree rate of turn and the IAF wanted atleast 22 degrees. We can infer from open literature that this 22 degrees has been achieved!
The article pointed out by Shiv puts rate of turn in a good perspective. That critical balance between the energy carried forward and rate of turn is the most important thing! If this balance is lopsided on any one side, then it gives a big window to the adversary.
However, the article doesn't speak about few scenarios. Like what if LCA was the chase plane. If the plane in front of it can out turn it, then the LCA will shoot out in front! Another aspect not covered in that article was evading short range A2A missiles! Even in the BVR situation, when adversaries lock on in a face on missile release, both would want to release the missile and turn away ASAP. Though turning rate is important there, but the exit velocity out of the turn is even more important!
Also the author of the article (and I am all with him) says lets have many planes rather than a fundoo plane! In that case, he says if you can outnumber your enemy in 2:1, then in a tail chase, even if your adversary out turns you, your partner behind you will get him as he would have lost momentum. But in most cases that I have heard, the dogfights havn't been as ABB ( A and B are the aircrafts from 2 sides). They have always been ABA (even an AAB is quickly reconfigured to ABA). Well in that case if B can turn sharper, it is a huge benefit. With some luck, he can shoot down both As.
But is LCA a air-superiority fighter?! I would hazard a guess and say no. Its basic aerodynamic configuration doesn't suggest so. If not, then lets wait till its role is properly defined. I am strongly with the article that Shiv posted. 3 multirole fighter can't replace 3 fighters, each one of which is dedicated to a role.
I have one more question from the readers of the article that Shiv posted. Is the capability of supersonic flight as low as has been downplayed by the author. Albeit in a dog fight barely anybody is even transonic, but what if you were the chase plane and your adversary was supersonic! He can evade you and your missiles by just accelerating (reminds me of the Mig-25 ). Also if he is the chase plane, well well. I am completely with the author that acceleration is critical, but how will one accelerate without a big push, and if you can push very hard, you will go supersonic (yes yes I know the aerodynamics and engine intakes have to change). My point is if you push hard, you will get transonic. Then what, decrease pushing power? That would be a waste of your engine power! Gurus kindly enlighten this nadaan balak!
P.S. All this apply to our choice of MRCA too. Like I have been saying, What is better 126 fundoo planes or 200 nearly fundoo planes at the same price? Even if you discount attrition, 2 in the air is much better than one out there!
The article pointed out by Shiv puts rate of turn in a good perspective. That critical balance between the energy carried forward and rate of turn is the most important thing! If this balance is lopsided on any one side, then it gives a big window to the adversary.
However, the article doesn't speak about few scenarios. Like what if LCA was the chase plane. If the plane in front of it can out turn it, then the LCA will shoot out in front! Another aspect not covered in that article was evading short range A2A missiles! Even in the BVR situation, when adversaries lock on in a face on missile release, both would want to release the missile and turn away ASAP. Though turning rate is important there, but the exit velocity out of the turn is even more important!
Also the author of the article (and I am all with him) says lets have many planes rather than a fundoo plane! In that case, he says if you can outnumber your enemy in 2:1, then in a tail chase, even if your adversary out turns you, your partner behind you will get him as he would have lost momentum. But in most cases that I have heard, the dogfights havn't been as ABB ( A and B are the aircrafts from 2 sides). They have always been ABA (even an AAB is quickly reconfigured to ABA). Well in that case if B can turn sharper, it is a huge benefit. With some luck, he can shoot down both As.
But is LCA a air-superiority fighter?! I would hazard a guess and say no. Its basic aerodynamic configuration doesn't suggest so. If not, then lets wait till its role is properly defined. I am strongly with the article that Shiv posted. 3 multirole fighter can't replace 3 fighters, each one of which is dedicated to a role.
I have one more question from the readers of the article that Shiv posted. Is the capability of supersonic flight as low as has been downplayed by the author. Albeit in a dog fight barely anybody is even transonic, but what if you were the chase plane and your adversary was supersonic! He can evade you and your missiles by just accelerating (reminds me of the Mig-25 ). Also if he is the chase plane, well well. I am completely with the author that acceleration is critical, but how will one accelerate without a big push, and if you can push very hard, you will go supersonic (yes yes I know the aerodynamics and engine intakes have to change). My point is if you push hard, you will get transonic. Then what, decrease pushing power? That would be a waste of your engine power! Gurus kindly enlighten this nadaan balak!
P.S. All this apply to our choice of MRCA too. Like I have been saying, What is better 126 fundoo planes or 200 nearly fundoo planes at the same price? Even if you discount attrition, 2 in the air is much better than one out there!
Re: LCA news and discussion
25 degrees, is it?!putnanja wrote:I remember couple of people mentioning here that the full flight envelope has been opened for LCA. That would mean the designed AoA of 25 degrees, max G of 9G and max speed of 1.6mach at designed altitude, and max altitude of 15kms has been tested, right?
Re: LCA news and discussion
I beg to differ- Its a compound delta relaxed stability airframe that has inherent characteristics that will help it run rings around most threats in the region. Combine this with the low rcs, decent range and the result is a great air to air asset.indranilroy wrote:@
But is LCA a air-superiority fighter?! I would hazard a guess and say no. Its basic aerodynamic configuration doesn't suggest so. If not, then lets wait till its role is properly defined. I am strongly with the article that Shiv posted. 3 multirole fighter can't replace 3 fighters, each one of which is dedicated to a role.
Re: LCA news and discussion
Relaxed stability is the hallmark of almost every 4th generation (and upwards fighter). you can come up with a list of planes in our neighborhood which have it. And if you think of it, a direct competitor to the LCA, the J-17 has it. How does compound delta make it super agile to run rings around threats. Oh and by the way, a fighter would like to be in the inside ring rather than going around rings in A2A. A compound delta is better than a delta, but a tailless (and/or canardless) design is certainly not going to be the most agile planform configuration.Bharadwaj wrote:I beg to differ- Its a compound delta relaxed stability airframe that has inherent characteristics that will help it run rings around most threats in the region. Combine this with the low rcs, decent range and the result is a great air to air asset.indranilroy wrote:@
But is LCA a air-superiority fighter?! I would hazard a guess and say no. Its basic aerodynamic configuration doesn't suggest so. If not, then lets wait till its role is properly defined. I am strongly with the article that Shiv posted. 3 multirole fighter can't replace 3 fighters, each one of which is dedicated to a role.
You actually pointed out the wrong points. LCA's agility is given by it's size, wing loading, large leading-edge slats, TWR. There are other small things like usage of the boundary layer through the splitter plate for delaying the flow separation at high AoA.
Sirjee, I am a big fan of the LCA. It is a good multirole fighter and for its size as you mentioned, it is a valuable asset. I only said that most probably, it will not be used in a air-superiority role!
Re: LCA news and discussion
Given the position of the airbrakes near the tail, can we use them in semi deployed state in a pitching role, almost like a elevator to increase AoA! Does anybody know of such usage, or can somebody disprove such usage (may be from the drag point of view)? May be this is not at all required as the pitching generated by the elevons is not the limiting factor. Any light?
But my question will hold again for the lift off. I know that using the air brakes in even a semi deployed state would increase drag. But it can help in bringing the nose up faster, which a problem with a tailless (or canardless) plan form like our Tejas! It seems to be a trade-off which can be optimized for shortest take off runs! Or not?!!
Just for kicks, here's our beauty using the airbrakes. http://www.bharat-rakshak.com/media/352 ... -chute.jpg
But my question will hold again for the lift off. I know that using the air brakes in even a semi deployed state would increase drag. But it can help in bringing the nose up faster, which a problem with a tailless (or canardless) plan form like our Tejas! It seems to be a trade-off which can be optimized for shortest take off runs! Or not?!!
Just for kicks, here's our beauty using the airbrakes. http://www.bharat-rakshak.com/media/352 ... -chute.jpg
Re: LCA news and discussion
AoA is not limited by the ability of an aircraft to pitch its nose upward. Above the critical angle of attack, an aircraft will stall, go into a flat spin and drop like a stone out of the sky.
Re: LCA news and discussion
I am aware of that! I am just speaking of getting a bigger moment to get to the required the desired AoAAnujan wrote:AoA is not limited by the ability of an aircraft to pitch its nose upward. Above the critical angle of attack, an aircraft will stall, go into a flat spin and drop like a stone out of the sky.
Re: LCA news and discussion
Saaar I was under the impression that the thundaaar-Bandaar was a more conservative airframe without relaxed static stability(or at least less unstable than the tejas). The compound delta on the tejas would certainly help with reducing drag and maintaining energy. The cleaner airframe would also help with supersonic high altitude performance which is critical for BVR. It's agile, has a low rcs, decent range and a good radar/ew suite- what more is needed for air to air dominance in our immediate neighborhood?indranilroy wrote:
Relaxed stability is the hallmark of almost every 4th generation (and upwards fighter). you can come up with a list of planes in our neighborhood which have it. And if you think of it, a direct competitor to the LCA, the J-17 has it. How does compound delta make it super agile to run rings around threats. Oh and by the way, a fighter would like to be in the inside ring rather than going around rings in A2A. A compound delta is better than a delta, but a tailless (and/or canardless) design is certainly not going to be the most agile planform configuration.
You actually pointed out the wrong points. LCA's agility is given by it's size, wing loading, large leading-edge slats, TWR. There are other small things like usage of the boundary layer through the splitter plate for delaying the flow separation at high AoA.
Sirjee, I am a big fan of the LCA. It is a good multirole fighter and for its size as you mentioned, it is a valuable asset. I only said that most probably, it will not be used in a air-superiority role!
Re: LCA news and discussion
Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
Re: LCA news and discussion
We may have to wait for "clearance" for the aircraft, for spares etc etc...Philip wrote:Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
Re: LCA news and discussion
Inspite of your bias, I am with you on this one!Philip wrote:Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
Re: LCA news and discussion
Are you trying to say that the LCA is a air superiority fighter. I don't think it is. I havn't come across anybody in the know who has ever even gone close to seeing LCA in that role! F-15s, Su-3x families, and let me dare say J-11 are air dominance fighters. Would you send a squadron of LCA to fight a squadrons of these air dominance fighters?! I will leave it that!Bharadwaj wrote:
Saaar I was under the impression that the thundaaar-Bandaar was a more conservative airframe without relaxed static stability(or at least less unstable than the tejas). The compound delta on the tejas would certainly help with reducing drag and maintaining energy. The cleaner airframe would also help with supersonic high altitude performance which is critical for BVR. It's agile, has a low rcs, decent range and a good radar/ew suite- what more is needed for air to air dominance in our immediate neighborhood?
LCA is a good multi-role fighter. LCA seems to me like a kick-a** point defence fighter with very admirable multi-role capability. I am not here to prove that we didnt develop a good plane. I love the LCA a lot and know in most respects it would trounce the JF-17s and JF-10s. But this is not because the LCA airframe is the sleekest one out there!
Instability: May I ask how will you quantify relaxed instability? The rate at which the amplitude of oscillations would increase along any axis! FBW would control that. I dont know of any open source where this critical data for this FBW dampening/relaxing is published for any of the fighters. I would be glad to be pointed to such a source! Without any such source I have to guesstimate from the sustained rate of turn. Is there any other way of guessing?!!
Drag Compound delta wing reduces drag, agreed (certainly over the delta). But what with respect to the other wing forms in a turn?
I really didnt get your BVR point. The point is not to be flying supersonic all the time. On detections planes reach higher altitudes and supersonic speeds for longer missile range. Everybody knows that. If you are contending that the LCA would get that point faster, I am not sure whether I should agree. LCA is light, so a long range BVR missile would be a bigger fraction of its weight. Hence it's critical advantage of a greater TWR would deteriorate faster than a heavier plane with slightly lesser TWR! The point would have been if LCA could sneak in and fire the BWR missile and scoot before the other fighter detects that LCAs are in the region. Though the LCAs are small and have a well shielded engine, it's airframe is not designed for low RCS. Infact you can easily search that they want to consider refining that later. In the absence of such stealth, lets say LCA detects a fighter, decide to fire a missile. for max range it has to accelerate towards the oncoming enemy. You can do the math, by the time it accelerates, launches and turns around, even with its small size it would have illuminated the enemy radar screens.
Range for a Air dominance fighter is critical. Not only penetration but also for having enough fuel to continue combat. As classically the guy who breaks out of the combat first, often doesn't go home. LCA has good range amongst multirole fighters. But amongst air-superiority fighters?!!!
That's why I think that I am justified to believe that Tejas can't be used against a air superiority fighter. It can be used to hunt multirole fighters, or used for A2G or A2A in formations with other air superiority fighters! With this I would let my case rest! We can definitely agree to disagree here! Or please show me valid points vis-a-vis other air superiority fighter. I am actually more eager to change my opinion than stick to it, but from whatever I know I can't wander away!
Re: LCA news and discussion
At the risk of going slightly off topic - may I point out the power of semantics ad rhetoric when used by specialists over decades?
In the 1950 and early 60s there were just fighters and bombers. The fighters could be ground attack fighters or just fighters
In the sixties we had the first appearance of "interceptor-fighters" - later termed "interceptors" These were supersonic, high flying darts carrying missiles to intercept the high flying Soviet bombers that were expected to deliver nukes..
By the time Vietnam ended, the "interceptor" had changed. It had a decent radar, the gun was back again, it was agile again, had a great T/W ratio and it could carry more missiles. This beast had to be differentiated from the old plain-Jane "interceptor". Ir was called the "Air Superiority fighter". It was a missile armed, radar toting jet version of the Spitfire, Me 109 or Zero.
To the "Air Superiority fighter" was added a superlative radar, some air to ground capability (to take out hostile radars with ARMs) perhaps thrust vectoring, long legs better capability for networking and this was called the "Air Dominance fighter"
It is best not to confuse things. Air Dominance fighters are the same as what was called "fighter" in 1945 albeit with jet engine, avionics, networking and better missiles. The names "Air Superiority" fighter and "Air Dominance" fighters came after those concepts were defined. But those concepts cannot be established by one single fighter. You need many fighters, AWACS, satellite capability, stealth and PGM capability for SEAD to take out enemy air defences with a view to gaining "Air Dominance"
In the 1950 and early 60s there were just fighters and bombers. The fighters could be ground attack fighters or just fighters
In the sixties we had the first appearance of "interceptor-fighters" - later termed "interceptors" These were supersonic, high flying darts carrying missiles to intercept the high flying Soviet bombers that were expected to deliver nukes..
By the time Vietnam ended, the "interceptor" had changed. It had a decent radar, the gun was back again, it was agile again, had a great T/W ratio and it could carry more missiles. This beast had to be differentiated from the old plain-Jane "interceptor". Ir was called the "Air Superiority fighter". It was a missile armed, radar toting jet version of the Spitfire, Me 109 or Zero.
To the "Air Superiority fighter" was added a superlative radar, some air to ground capability (to take out hostile radars with ARMs) perhaps thrust vectoring, long legs better capability for networking and this was called the "Air Dominance fighter"
It is best not to confuse things. Air Dominance fighters are the same as what was called "fighter" in 1945 albeit with jet engine, avionics, networking and better missiles. The names "Air Superiority" fighter and "Air Dominance" fighters came after those concepts were defined. But those concepts cannot be established by one single fighter. You need many fighters, AWACS, satellite capability, stealth and PGM capability for SEAD to take out enemy air defences with a view to gaining "Air Dominance"
Re: LCA news and discussion
you are confusing the role of an air-brake with that of an elevator. basically the air brakes are FBW actuated or pilot actuated when the need is to drop speed in a hurry and no aircraft that I know of uses them to increase its pitch up moment- some canard aircraft like the Gripen (which use their canards as an elevator) use their canards for airbrakes but non-canard aircraft don't do the opposite. First of all air-brake actuators are not designed for the kind of reaction times that an elevator's actuator is designed for.indranilroy wrote:Given the position of the airbrakes near the tail, can we use them in semi deployed state in a pitching role, almost like a elevator to increase AoA! Does anybody know of such usage, or can somebody disprove such usage (may be from the drag point of view)? May be this is not at all required as the pitching generated by the elevons is not the limiting factor. Any light?
But my question will hold again for the lift off. I know that using the air brakes in even a semi deployed state would increase drag. But it can help in bringing the nose up faster, which a problem with a tailless (or canardless) plan form like our Tejas! It seems to be a trade-off which can be optimized for shortest take off runs! Or not?!!
When airbrakes are deployed, depending on the nose position asked by the pilot (up, down or nearly 0 deg AoA), the FBW will counter it or compensate for it..if the pilot activates the air-brake in a dive, the FBW will basically increase elevon deflection to counter the pitch up moment of the air-brake and vice versa. For quick nose up requirements, the two piece elevons are more than enough when combined with the natural instinct of the LCA to want to pitch up (being unstable in pitch). just compare the size of the elevons to those of the airbrakes and it will be obvious that for a pitch up moment the elevons will give you a huge advantage over the air-brakes.
Tejas 3 view drawing
Re: LCA news and discussion
there is a source. and a very authoritative one that cannot be questioned. Air Marshal Philip Rajkumar in his book statedindranilroy wrote: Instability: May I ask how will you quantify relaxed instability? The rate at which the amplitude of oscillations would increase along any axis! FBW would control that. I dont know of any open source where this critical data for this FBW dampening/relaxing is published for any of the fighters. I would be glad to be pointed to such a source! Without any such source I have to guesstimate from the sustained rate of turn. Is there any other way of guessing?!!
"The software in the DFCC is broadly divided into 2 parts. The first part is the CLAW which decides how much the control surfaces should move depending on the flight conditions. From a mathematical flight model of the aircraft based on wind tunnel and CFD data, control engineers calculate the amount of control deflection required to control the aircraft at various points in the flight envelope, and create a big look up table which is stored in the computer memory. The flight conditions are sensed by the air data probes on the aircraft and passed on to the computer. The computer accesses the look up table in real time and decides the amount of control deflections required.
Each computational frame lasts 12.5 milliseconds or in other words, is repeated 80 times per second, but the actual movement of the control surface takes place about twice per second."
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Re: LCA news and discussion
You are confused. The problem with the LCA because the weight distribution is more towards it's Musharraf than it's nose, is that the nose tends to point skywards in a wink, if the control system does not keep the nose down !. This is unlike a conventional aircraft where the nose tends to point towards the ground all the time.May be this is not at all required as the pitching generated by the elevons is not the limiting factor. Any light?
But my question will hold again for the lift off. I know that using the air brakes in even a semi deployed state would increase drag. But it can help in bringing the nose up faster, which a problem with a tailless (or canardless) plan form like our Tejas! It seems to be a trade-off which can be optimized for shortest take off runs! Or not?!!
Once when I was in my teens, I asked my dad's eldest brother who was a member of the Railway board a question. Why dont our trains have toilets like in other countries/airplanes where the waste is collected in a tank and then disposed off hygenically ,rather than the mess we see on the tracks in railway stations (bombed with unmentionable refuse if you are under a bridge and a train is passing overhead). He gave me an avuncular look and said, see, the problems are different. In airlines/ other countries, journeys are short, people hardly use them to the extent we do and plus they have some modicum of civic sense. Not so with the typical profile of Indian Railway passengers, where the journeys can last days.. And the "problems" are different.
.. For goras, getting bowels moving is the problem for Indians, getting it stopping is the problem!For the goras, the problem is constipation, for us it is diarrhea
Similarly, the problem is different for an unstable aircraft like an LCA and conventional aircraft. For LCA, the the problem is to stop pitching , while for a conventional aircraft it is to get it pitching! . In fact, the Elevon in the LCA will be sized to give adequate control force to moderate max pitch up moments, more than anything , rather than get it there .So getting to X deg AoA is not the problem, the LCA will get it there by itself, the problem is to STOP and hold it at X deg.
So dont worry, have curry. You are trying to solve somebody else's problems, not the LCA's
Re: LCA news and discussion
vina wrote: Similarly, the problem is different for an unstable aircraft like an LCA and conventional aircraft. For LCA, the the problem is to stop pitching , while for a conventional aircraft it is to get it pitching! . In fact, the Elevon in the LCA will be sized to give adequate control force to moderate max pitch up moments, more than anything , rather than get it there .So getting to X deg AoA is not the problem, the LCA will get it there by itself, the problem is to STOP and hold it at X deg.
This is as elegant and succinct an explanation as I have ever seen
Re: LCA news and discussion
OT.... Well it could be a political decision to reward US with certain big ticket defence deals as part of Indo-US N agreement something the decision makers on both the sides could have agreed to at highest level. So if C-17 or F-18 makes it inspite of all the rejections from US on LCA etc it should not surprise or worry us.Philip wrote:Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
The positive impact for Tejas will be that we could be looking more closely at Europe to co-operate on that program and possibility of EJ200 powering Mk2 types looks more real then ever.
Re: LCA news and discussion
Lovely, illuminating discussion!
Reading this, I was wondering why the LCA didn't have canards, if they're so useful.
I found this:
Answers that question (or appears to, if it's accurate), but poses another. This is more a general aeronautics question than a strict LCA one, but anyway: why don't canards make that much of a difference to the LCA's performance?
Reading this, I was wondering why the LCA didn't have canards, if they're so useful.
I found this:
http://www.militaryphotos.net/forums/sh ... 9-redesignThe unique cranked-delta design, and the overall aircraft structure with significant wing-fuselage blending, etc. allows for incredible manoverability without the need for canards, which further reduces its RCS compared to similar aircraft, like the Gripen and the J-10. Interestingly, the LCA was initially designed with canards, but were later removed when the mastering of the wing design made for no significant handing improvements with canards.
Answers that question (or appears to, if it's accurate), but poses another. This is more a general aeronautics question than a strict LCA one, but anyway: why don't canards make that much of a difference to the LCA's performance?
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Re: LCA news and discussion
Some day, we have to wake up to realpolitik.Philip wrote:Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
Re: LCA news and discussion
When will our guys ever learn? It was initially selecting an American partner instead of a European one that set the LCA program back at least a decade(due to sanctions after Pokaran-2). Now our guys want the Americans again as consultants. Sheeeshhhhhhhh.
Re: LCA news and discussion
Vina and Kartik thanks a lot for the clarifications. Indeed, what was I thinking!! Shiv thanks a lot for the article!
To show myself down more let me add one more observation, the air brakes are almost above the elevons! so the moment arm length will be the same. So which designer in his right mind would not rather increase the elevon size, rather than use the piddly air brakes for creating additional moment!
Curry it is for me then
To show myself down more let me add one more observation, the air brakes are almost above the elevons! so the moment arm length will be the same. So which designer in his right mind would not rather increase the elevon size, rather than use the piddly air brakes for creating additional moment!
Curry it is for me then
Re: LCA news and discussion
willy, they have already selected EADS, so why cry now ? I do wonder why they didn't select dassault though. EADS doesn't have experience with carrier-borne aircraft.
Re: LCA news and discussion
Appreciate the Gyan doled out though I wonder if this "look up" table has to be re-done and completely retested in the case of a new, heavier motor. I suppose some of the re testing can be handled through accurate simulation.
Re: LCA news and discussion
Since the radar is up, has there been any discussions to start integrating various missiles/LGBs to LCA?
And is ther any chance or integrating european or american missiles ?
And is ther any chance or integrating european or american missiles ?
Re: LCA news and discussion
Cloud messing up the action again today- this could be some preparation for the mini show on the 23rd.
Re: LCA news and discussion
There was a report/speculation some time ago that LM was selected because it is the only one with experience in developing a single-engined naval fighter (F-35C).Rahul M wrote:willy, they have already selected EADS, so why cry now ? I do wonder why they didn't select dassault though. EADS doesn't have experience with carrier-borne aircraft.
Re: LCA news and discussion
I love this new and innovative use of the word "Musharraf "
I do have to say that the quality of post in the LCA thread has improved dramatically in the past week, lets hope that this continues in the future.
I do have to say that the quality of post in the LCA thread has improved dramatically in the past week, lets hope that this continues in the future.
vina wrote:May be this is not at all required as the pitching generated by the elevons is not the limiting factor. Any light?
You are confused. The problem with the LCA because the weight distribution is more towards it's Musharraf than it's nose, is that the nose tends to point skywards in a wink, if the control system does not keep the nose down !. This is unlike a conventional aircraft where the nose tends to point towards the ground all the time.
Re: LCA news and discussion
LSP-6 will be used to further open AOA ,i don't know why only that bird has been set a side for further opening up Tejas AOA , we might have achieved AOA of 22 set by IAF but may be ADE wants to open it up further ?
http://www.lca-tejas.org/variants.htmlLSP-6 will be used to increase the AOA
Re: LCA news and discussion
Sorry for the OT remark, but this cannot happen - there is the track, sleepers, ballast and the bottom support which is often concrete bed, at least the width of the track, often a few inches more... Unless someone is showering his/her blessings (orally) through the window, then it may hit you...vina wrote:... (bombed with unmentionable refuse if you are under a bridge and a train is passing overhead).
I heard the new German tech coaches have a special lever that releases accumulated Inner-Pakistaniyat when train goes more than 80kmph (perhaps they learnt it from the movie Bullet Train where a bomb goes off if train goes below 80kmph)...that also shows how much we care for the rural masses and their air/ground water quality
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Re: LCA news and discussion
Political decision? No, I think not. Why offer peanuts when they can offer far more lucrative offers such as the C17? Also, why take the risk of screwing a core program such as the NLCA? The reasons for this penchant to gravitate towards a whimsical supplier seem more sinister and dare I say, more technocrat oriented - H1 visas for children and the like it seems to me.Austin wrote:OT.... Well it could be a political decision to reward US with certain big ticket defence deals as part of Indo-US N agreement something the decision makers on both the sides could have agreed to at highest level. So if C-17 or F-18 makes it inspite of all the rejections from US on LCA etc it should not surprise or worry us.Philip wrote:Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
The positive impact for Tejas will be that we could be looking more closely at Europe to co-operate on that program and possibility of EJ200 powering Mk2 types looks more real then ever.
As far as LM being the only one with the ability/expertise to help in this area, not necessarily true - remember the Shar came out of BAE; not to mention, Dassault's Super Etendard. So, both Dassault/EADS should have enough background in getting single engined types off carriers. Even the russkis have some experience via the Su-25 + Yak; in fact their model of STOBAR ops is closest to what the IN will have in its next 3 carriers.
So, I am afraid there has to be more to this than purely political-technical reasons. I was surprised about their decision to go for GE-F404s despite the sanctions post 98 and all the whining thereafter, I became a bit suspicious when the additional purchase of 40 404s was procured, then the constant refrain to seek consultancy from LM/Boeing, then the inclusion of the GE-414 for the MkII.
Could be wrong of course, and perhaps there is a technical reason that only LM-US types can provide.
CM
Re: LCA news and discussion
A good read http://desktop.aero/appliedaero/configu ... rocon.html. May be for its weight and size, the LCA doesn't need the canard controls.vardhank wrote:Lovely, illuminating discussion!
Reading this, I was wondering why the LCA didn't have canards, if they're so useful.
I found this:http://www.militaryphotos.net/forums/sh ... 9-redesignThe unique cranked-delta design, and the overall aircraft structure with significant wing-fuselage blending, etc. allows for incredible manoverability without the need for canards, which further reduces its RCS compared to similar aircraft, like the Gripen and the J-10. Interestingly, the LCA was initially designed with canards, but were later removed when the mastering of the wing design made for no significant handing improvements with canards.
Answers that question (or appears to, if it's accurate), but poses another. This is more a general aeronautics question than a strict LCA one, but anyway: why don't canards make that much of a difference to the LCA's performance?
But how does the LCA wing design delay edge separation? Classically a compound delta wing seems to have a bigger sweep angle near the body joint. Somewhat like a LERX in a swept back wing configuration. This generates the vortices which would generate lift at high angle of attacks. But in the case of LCA's wings it's the opposite. the sweep back angle is lesser near the body!
I understand that this has many advantages:
1. provide for a more blended wing join, leading to lower drag and increased manoeuvrability
2. for equal wing area increases the aspect ratio make the plane more roll friendly and decreasing induced drag without almost no increase in parasitic drag,
4. provide more space for fuel etc etc.
But even then the edge separation would set off earlier, isn't it? Is it a compromise made for the above advantages as enough AoA can be achieved otherwise? Or is there something else? May be it explains why the LCA initially had problems of clocking more than 18 degrees rate of turn? How has it been overcome?
P.S. Vina, if you reply to this post, I would love to hear another childhood story of yours. But this time, please don't base it on sh*t. Your posts are followed by other posts (I was so tempted to reply to that myself). Obviously we don't want a discussion about p*tty on our LCA thread ... lol
Re: LCA news and discussion
I think what they were reluctant to release is some testing techniques and not technologies - as in which may come with the F-18. While the consulting could have helped India overcome a problem for good, a F-18 will not allow India to overcome some difficult technologies (India will get to use them but not build them).Philip wrote:Can someone give me an honest answer to this perplexing Q.The US denies us open collaboration on the naval LCA ,forcing us to go to the Europeans,but still preaches to us that the F-18SH is what we should buy for the MMRCA contest.How on earth can we trust it and shouldnt the MOD AKA openly tell off the US that they cannot have it both ways.AFter the reejction of assistance on the naval LCA we should have dropped the F-16 from the list pronto! This would light a fire under Uncle Sam°s nether regions and act as a warning for any future military deals with US,cooperation either.... all the way or the highway!
Two different things.
Re: LCA news and discussion
Remember the discussion few days back about a crack in the LCA wing!!! can see it hereindranilroy wrote:But even then the edge separation would set off earlier, isn't it? Is it a compromise made for the above advantages as enough AoA can be achieved otherwise? Or is there something else?
I think it is a turbulator! http://en.wikipedia.org/wiki/Turbulator
It is a mechanical turbulator. Read here http://www.mh-aerotools.de/airfoils/turbulat.htm
Mechanical Turbulators
A mechanical turbulator consists of a modification of the airfoil shape, which causes large local gradients in the shear stress of the fluid, which finally cause transition. It can be attached to the surface as a straight tape strip (also called a 2D turbulator) or it can be distributed in a certain area like zig-zag tapes or single bumps, spaced equally. A different possibility, which has been used on free flight models, is a wire, which is mounted on small struts in front of the leading edge. This device is less sensitive to changes in angle of attack, but causes larger additional drag.
Typical values for turbulator height on model aircraft range from 0.2 for higher Reynolds numbers to more than 1 mm for free flight models
Re: LCA news and discussion
I was right. Harry had written here http://forum.keypublishing.com/archive/ ... 16857.htmlindranilroy wrote: I think it is a turbulator!
... wing area is measured only upto the intakes below the turbulator(crank) point so ...
Re: LCA news and discussion
No it is not. One can read about the F-16 XL project which had a cranked arrow design. Though that wing had three steps, it wing join is very similar to the LCA.indranilroy wrote:
But even then the edge separation would set off earlier, isn't it?
Pic: http://attach.high-g.net/attachments/f16xl_112.jpg
Similar to the LCA
One can read about the whole tests in the report named "Review of Cranked-Arrow Wing Aerodynamics Project: Its International Aeronautical Community Role" from NASA, Langley.XL did not need a canard, as it already possessed superior nose pointing capability, significantly better than the F-16. A canard was studied but proved to be of no significant benefit anywhere in the flight envelope.
One can read some interesting things about the XL here: http://www.f-16.net/f-16_forum_viewtopi ... rt-15.html
and an interesting to and fro about LCA's requirement of canards here http://forum.keypublishing.co.uk/showth ... 431&page=6
Mods: if this is common knowledge, please delete the series of my posts on LCA's wing shape!
Re: LCA news and discussion
this is hilarious CM ! are you implying that the guys involved in the decision making are somehow managing to send their children to the US (that is an F1 visa) or that their children are getting H1 visas to work in the US on the basis of their parent's decision to support a US product ?! I'm afraid nothing can be further than the truth in this regard..the US consulate that gets visas done doesn't quite take this into account I'm afraid..Cain Marko wrote: The reasons for this penchant to gravitate towards a whimsical supplier seem more sinister and dare I say, more technocrat oriented - H1 visas for children and the like it seems to me.
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Re: LCA news and discussion
Kartik there is a question for you on Newbie thread by Gaur regarding Diverterless Supersonic Intake (DSI).Kartik wrote:...