Is the AMCA a pipe dream that will become a dead Albatross?

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brar_w
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 09 Jul 2015 04:08

Kanson wrote:
brar_w wrote:Dry thrust is not an issue with the JSF..It never had super cruise as a requirement because range was the absolute driver for the design along with the requirement for a single engined fighter. The bypass ratio of the F135 and the thrust class is designed around the engine. If they wanted a super cruising air to air fighter they could have made one. Use an engine with a similar bypass ratio to the F-119, reduce the 2000 pound bomb carriage and lift the CAS range and loiter requirements and you would have had a different looking aircraft with a different mission profile. It would have made a lousy F-16 or F-18 replacement but you would have gotten that performance from it without needing to get more dry thrust (or wet for that matter). All in all thrust is important and thrust to weight is an indicator, but the real indicator is and always is thrust to weight minus drag and as your design changes and evolves as they do when multi role mission sets are demanded you have to make trades..Its no longer the "NOT A POUND FOR AIR TO GROUND mentality that survives in multi-role fighters...


Problem is not to US, it is for whom who buy F-35 but cannot get F-22. And to tackle Su varieties and the coming PAK-FA , J-20 etc, it is an eternal dilemma whether F-35 alone is sufficient.


You mean the same operators that operated the F-16 or the F/A-18 vs the likes of Mig-29, Su-27, Mig-31, Mig-25 among others?? Yeah..The answer to get that level of capability (i.e. multiple stealth types) is to invest money in developing or acquiring them, however that is not within reach for most NATO customers so they will invest in an aircraft just like they invested in the F-16 back in the day and that has served them quite well over the decades through an MLU and upgrades)..As far as thrust, and particularly dry thrust, you will not get a heck of a lot of capability addition unless you are willing to sacrifice in other areas..Its quite simple..short of adaptive engines you will have to trade other areas if you want to get more dry thrust and more overall thrust. Its a multi-role fighter that takes over the F-16 mission set that includes air to air, CAS, SEAD/DEAD and needs a combination of design features to provide supersonic capability, subsonic loiter, cruise, ability to give good range without bags at 30,000 (Targeting pods and weapons operate best here) and also have some ability to go up and fight the air battle. The F-16 is no F-15C up at 45,000 fleet. The F-35 is also no F-22A at 45-50K feet but adaptive engines will most likely narrow that gap (but those are some time away)..Similarly the F-22A despite of the "A" doesn't do so well in terms of range and range/payload when flying at 30,000 feet..Its all a trade-off.

How is a NATO nation that uses an all F-35 fleet or a mixed F-35 and F-16 any different from the French that operate an all Rafale or a Rafale+M2K fleet?? Air Combat is not just about being able to slug it out against near peer threats, you have to strike at ground targets, support your soldiers, conduct ISR, Electronic Warfare and support other services in whichever way you can. When Nations can afford only one fighter they choose one that performs each of the mission-sets..Thats a primary reason that most defensive air-forces in Europe do not have a mach 2.5-3 Interceptor to fend off against bombers, a mach 2 figther to fend off against Su-35's, and PAKFA's and a subsonic strike aircraft for SEAD and perhaps some A-10's for CAS. None can afford that so they seek a balance in all mission sets and as they did with the F-16 look to constantly maintain a technology edge when it comes to systems, sub-systems, weapons, PGM's and support..A common aircraft allows them to channelize these investments...Its come to a point where they are co-investing in BVR Missiles (Meteor), AEW aircraft and other support. Its not just an F-35 vs Su-35 or PAKFA its an F-35, flying with AEW, with MEADS and other systems supporting from the ground. Neither Japan, Soko or NATO are looking to invade and conduct a "battle of britain" type campaign over Russia, they'll be wiped out by Nukes if it ever came to that.

Anyhow back to the AMCA - Like I said you can always design a pure air to air fighter and get the maximum performance in many relevent areas..When you begin to add multi-role capability and missions you will have to make trades..You can't say I'll get the best of the JSF, best of the Rafale, and best of the F-22/T50 and roll that into my plane..Unfortunately it doesn't work that way. The ATF competition was the best contrast when it came to evaluating various trades and what "cost" each design team had to pay for its decisions..As one "acquisition community member" remarked Northrop McD's team had to go report to their board that they developed most likely a stealthier aircraft, a faster aircraft and one that had more range but lost simply because of one design parameter in that the US air-force wanted a cranking ability which it really could not perform as well...That was just in the Air to Air (Mostly) fighter..When you start to work with the operators in terms of going over the threat and seeing what sort of capability is required you have to scratch your heads and look for trades, and this determines your level of stealth, level of performance, level of sensor coverage, sheer number of sensors.... Stealth will be the biggest challenge here and it will be interesting to follow this program over the next decade to see what maneuverability and speed/supercruise trades are made for it...
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby NRao » 09 Jul 2015 06:13

Marvelous article in AWST.

Paid, so I will try and type as much as I can.

NASA Takes Venture Capitalist Approach To Funding New Concepts

Trying, failing, learning and trying again was how the aviation industry built itself up over its first half century. But since the “nothing is impossible” days of the 1950s and ’60s, the consequences of failure have escalated. And so has the aversion to risk, not only among manufacturers but also within the research agencies charged with taking greater risks to develop tomorrow’s high-payoff technologies. When NASA restructured its aeronautics research in 2014 to ...


When NASA restructured its aeronautics research in 2014 to focus it on strategic challenges facing aviation over the next 20-40 years, it also sought to recapture the culture of taking risks, failing early and learning fast that marked the X-plane heydays of the 1950s and '60s. The idea is to recapture it in a small way, at least, by bringing an entrepreneural approach to its "seedling" efforts to develop new ideas.


As I have stated, umpteen times, to be on the very leading edge, one has to have people who will take humongous risks.

NASA is actually reviving that culture - to take huge, huge risks.

IF India wants to be a "power" of any sort - even in the IOR - India better start taking larger risks and not be cowered down by failures.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby shiv » 09 Jul 2015 13:37

In response to Ajai Shukla's article
http://idrw.org/tejas-mark-ii-aeronauti ... tic-goals/
I read two articles with great interest – “First Tejas Mark II engine to arrive in September” and “From Tejas to AMCA” – on July 6, both by Ajai Shukla of the Business Standard. As a retired Colonel of Indian Army, Shukla speaks with a certainty that comes from experience and in these articles he rails against “self-appointed patriots who see no irony in their advocacy of expensive foreign weaponry”. I suppose Shukla means this description to include Indian Air Force Ex-Chiefs of Air Staff Fali Major and PV Naik who certainly are advocating buying foreign combat aircraft. Let us be realistic, every combat aircraft ever flown by the IAF so far was foreign made i.e. Russian or French. So it is hypocrisy for Shukla to deride foreign weaponry when India has been relying on foreign weaponry for the last 67 years.

In the first article Shukla essentially argues that modifying the Tejas to create the Mark II using the GE-414 will be easy as “F-414 is no larger than the F-404?. Keep in mind that the Tejas was designed to use the F-404 engine except the weight and drag of the Tejas is too high and so it appears underpowered. The Gripen which was considered by the IAF uses the same F-404 engine as the Tejas except the weight and drag of the Gripen was properly optimised. It may be true that with another 3 years of redesign of the Tejas to use the more powerful F-414 engine will yield a good cheap Tejas Mark II combat aircraft but until it is actually tested no one will know for sure, so can the IAF really wait another 3 years on just the promise that Tejas Mark II will work properly?

Regarding the AMCA Shukla argues that it will be a success because the IAF is part of the project from day one, and that once clearance is obtained for spending $4 Billion and design work is started, then in approximately 15 years time, the AMCA will be reality, even though so far the engine which will power the AMCA has not been decided on.

There is absolutely no harm in having an optimistic vision of the future but what about the present? War is not like a cricket match, it carries real consequences. So, if India were in a war with Pakistan or China in a few years it is not possible to tell them that India is not ready yet, please attack again in a few years time. The depletion in numbers in the IAF is happening right now, and maybe increasing production of Su-30MKI will buy some time, but it will not buy the 3 more years to design the Tejas Mark II plus another 3 years to build and induct sufficient number of Tejas Mark II.

For the IAF pilots it is a matter of life and death, for the citizens of India it is a matter of protecting your sovereignty. The minimum role of the commentator is simply to be realistic and it does seem that relying on the Tejas Mark II is not being realistic, so India definitely needs to reduce the risk by importing foreign combat aircraft, at least until you have a Tejas Mark II that really works well and that you know you can manufacture in large numbers. Regarding the AMCA, of course India needs to work on the design and prototyping anyway, but India still has to consider other options as well, i.e. wait until the AMCA is actually working and then you can rely on it. To put it another way, of course India should spend the money to design the Tejas Mark II and also the AMCA, but just don’t rely on them until you have fully functioning prototypes with initial operational clearance (IOC). Try not to repeat the ongoing misery of the IAF for the last 5 years waiting for the Tejas to get IOC.

The biggest problem that India has is that every project is funded only when the politicians think there is a practical need for it. For example this design and prototype of Tejas Mark II should have been completed 10 years ago along with the initial prototype of Tejas, because the F-414 engine is from the same family as the F-404 engine and has been in existence for 20 years now. Yes, I am aware that it sounds like hindsight, but the fact is that India should have designed and prototyped Tejas and Tejas Mark II at the same time so that you could have selected whichever version works better i.e. find the problems earlier so you can make the choices earlier. Indeed any engineer in any branch of engineering will tell you that the best way to fully understand a design is to to make two or more versions and compare them.

That is why I really believe that India should not finalise the design for the AMCA right away.

Instead of shooting for the goal of the stealth capable 5th generation AMCA with a pair of 110 kN engines (which India does not have right now anyway) to be built in the next 15 years, India needs to aim for an intermediate goal to be delivered in 5 years. The intermediate goal will be a much simpler twin-engine combat plane without stealth in two configurations at the same time i.e. a first small configuration using a pair of 79 kN F-404 engines and a second slightly larger configuration using a pair of 98 kN F-414 engines. Then you can compare the two configurations and learn how to scale the airframe in size based on the power of the engines. Indeed, these configurations are test beds for the final design which will be the largest in size and complexity. Also you can practice applying stealth technology on the small and medium planes to begin with. Once India has successfully done that, then India is ready for the next design/prototype step i.e to get the best configuration using the more powerful 110 kN engines which hopefully by that time India will have obtained from USA or Europe.

In other words the 5th generation AMCA project will be much easier to implement if you take it in steps. In addition the smaller twin-engine combat plane designs which were developed as intermediate goal can be adapted as combat aircraft in lesser roles. If India takes the project in steps, the chance of success is much higher. But until India is successful in doing this, you obviously also have to keep buying enough foreign combat planes to keep the IAF fully operational.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby Philip » 09 Jul 2015 20:49

What the author advocates is building a 4++ gen aircraft with some stealth features thrown in,an achievable goal ,a step up from the LCA.However,there is an aircraft which is already in service which if tweaked fits the bill perfectly,which we are also upgrading for the IAF the MIG-29UG! The IN's 29K version is supposed to have some stealth coatings,etc. on it,making it less detectable than the earlier basic avatars. Imports are absolutely needed to keep numbers and capability happy. A simple rule of thumb for costs,the most important factor:

I Rafale = 2 SU-30MKis=4 MIG-29Ks/UGs. The MIG-29/35 is in the same weight /class of the Rafale,was a competitior.It comes with an AESA radar option,TVC,BVR AAMs,PGMs,including BMos-M,etc. Which type do you think would survive in a dogfight either at BVR or WVR range,1 Rafale or 4 MIG-29s?

One could skip the entire "interim" less-stealthy AMCA ,save a lot of cash for the moment (150,000cr for the AMCA development according to prof.PD) by upgrading MIG-29s with added stealth,TVC,AESA; continue apace with the LCA MK-2 ,and (as NR agreed with me-though he wanted the FGFA scrapped) since it appears that some FGFAs will be acquired as the 5th-gen fighter,earmark the AMCA as a true 6th-gen fighter. What is the point in developing in 15 years time a smaller ,less capable 5th-gen aircraft when by 2020+ we will have the first FGFAs entering service with the IAF? Why reinvent the wheel,when we can have 4+++ aircraft carrying the same weaponry at much lower acquisition and operating costs? We can leverage the tech we're getting from the FGFA,LCA,etc.,evaluate these with the aircraft in service and then develop our own exotic capabilities ,and once satisfied that we have all the key components within our grasp,put them all together as the AMCA 6th-gen,a step up over the 5th-gen FGFA. 15 years down the line we will also have our first desi UCAV in service ,whose op experience may require us to revise our ASR for the AMCA.
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby fanne » 09 Jul 2015 20:55

or more SU30MKI (124 in number)

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby ramana » 09 Jul 2015 22:50

shiv, The author is leading into the Technology Demonstrator (TD or FSED-1) trap that LCA fell into.

IAF insisting of FSED-1 was right one at that time for there was long gap between HF-24 and LCA and technology was futuristic by all parties.

To demand same path for AMCA will lead to same pitfalls that IAF is facing right now.


There is nothing that says some parts of the AMCA technology cannot be proofed on a few LCA demonstrators already built which can be used as technology proofing platforms.


BTW would like to see the $4B allocation over 15 years that is being asked. What is it for? Its not much. Works out to $267M/year on linear allocation.
Using EVM we can track progress by allocating 6/67% completion every year. Unrealistic but is start. We would need actual spent by ADA on AMCA every year.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby NRao » 09 Jul 2015 23:58

Instead of shooting for the goal of the stealth capable 5th generation AMCA with a pair of 110 kN engines (which India does not have right now anyway) to be built in the next 15 years, India needs to aim for an intermediate goal to be delivered in 5 years. The intermediate goal will be a much simpler twin-engine combat plane without stealth in two configurations at the same time i.e. a first small configuration using a pair of 79 kN F-404 engines and a second slightly larger configuration using a pair of 98 kN F-414 engines. Then you can compare the two configurations and learn how to scale the airframe in size based on the power of the engines. Indeed, these configurations are test beds for the final design which will be the largest in size and complexity. Also you can practice applying stealth technology on the small and medium planes to begin with. Once India has successfully done that, then India is ready for the next design/prototype step i.e to get the best configuration using the more powerful 110 kN engines which hopefully by that time India will have obtained from USA or Europe.


Multiple issues:

* The "small configuration using a pair of 79 kN F-4040" is the original MCA. (Aside: The major diff was the MCA did not have a vert fin, had a TVC and was not "stealth" - but that is a diff matter)
* Around 2005, the IAF (CAS I believe - I posted in the AMCA thread) probed into the possibility of "stealth" in the MMRCA. When the IAF found it was not possible the CAS requested it be in the the AMCA. AND, he gave *reasons* why "stealth" (we may not agree with what he stated, but he did give reasonS)
* Then 5 years - when does it start? I assume he means LCA-MK-II around 2020ish, 5 years after that these two planes he is proposing and then some time after that (I assume 203ish) a mature "5th Gen" AMCA. Not worth it, fo rthe following reason
* For one the AMCA was born out of the MCA, which was exactly what this person is proposing. Next, the research and development in the AMCA is very mature. So, why would one invest in TWO intermediate planes is beyond me
* I am extremely glad that such guys were not there on the internet when the LCA was being conceived. Somebody should inform him that the LCA is a 4th Gen plane .................. believe it or not India SKIPPED gens 1,2 AND 3!!!! Yikes. THAT is real scary
* Finally, (there are others) I think it is a matter of nerves - as it applies to unknown techs - more than anything else. Those that do not have it will tend to hedge - and that is fine. But hedging is not meant for everyone.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby ramana » 10 Jul 2015 01:27

NRao, Please link to the IAF chief's 2005 statement. I think its important to understand why he felt stealth was needed.

Thanks, ramana

---
Never mind. First page of AMCA thread has oodles of requirements from IAF and what is being done since 2010.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby shiv » 06 Sep 2015 16:02

Cross posting here since this article has now been located online

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby Karan M » 08 Sep 2015 23:41

There is a lot of stuff in the above article by Prodyut Das which is patently unproven or countered by facts, and that too as a given. Oh well. The world perhaps need the Prasun Senguptas and Prodyut Das's and Manoj Joshis for masala. In between he puts forth some valid points as well but ignores the time and other consequences (eg stealth LCA variants for TD) and so it goes.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 08 Sep 2015 23:56

Poorly crafted argument imho. While generational categorization is not a technical or scientific thing but some folks do tend to get carried away with it. Substitute 5th generation with Next Generation and the argument sounds a lot better, with the Next Generation being whatever that follows the LCA as far as development and induction is concerned. Attempts to divide capability neatly into a finite set of "generations" works for some things and not for others. Besides this, the article does a poor job in defining the genesis of 5th generation and how the capability came into being. As per his definition all non-FBW equipped fourth generation fighters (F-15, Original Mig-29) would be 3rd generation fighters :)

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby Karan M » 09 Sep 2015 00:23

Frankly, I have given up on Shri Das's works actually containing anything practicable that can be implemented in the Indian context or meet the IAFs needs. He has a profound need to bat for HAL whilst baiting ADA and then discounting anything that does not meet his predefined viewpoints as "unproven", "gimmickry" etc. Whilst there are some interesting and logical points made (i.e. think of countering stealth not merely inducting the same) he mixes the entire stuff up so much it becomes a hard read.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 09 Sep 2015 01:15

Duplicate..
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 09 Sep 2015 01:15

Duplicate..
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 09 Sep 2015 01:15

Deleted..
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 09 Sep 2015 01:15

Not only counter stealth but also counter-counter stealth. It all goes hand in hand. You have to both deny the opponent's stealth advantage (J-20, J-31, cruise missiles,. Ding Dong UAV's) while also reducing the potency of its IAD's. And forcing the opponent to exist in a different spectrum is a victory in and of itself because it just so happens that counter stealth technology as we know it is expensive, and not as tactically potent from a kill chain perspective as the status quo as far as integrated air defense systems are concerned. To top all that these same basic science and development investments translate to other systems, from electronic sensors, to stealth for UAV's, to advanced computing etc, all of those investments for the AMCA will pay off in other programs.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby shiv » 09 Sep 2015 08:39

Cross post
NRao wrote:Is there one definition for 5th Gen planes? I do nto think so. He can say what he pleases and he will be right - as all others are.


Nrao this actually makes Das' argument correct.

Das says about the logic that led to the creation of the F-22:

Actually this bundle of requirements has less to do with direct general combat lethality and more to do with the American views of Power projection worldwide consequently Air Superiority over hostile territory.

i.e This was an American definition back then and as you have pointed out, the Americans have changed their definition:

NRao wrote:So, wiki:

According to Lockheed Martin, the only fifth-generation jet fighter currently in operational service is their own F-22 Raptor.[2][8] US fighter manufacturer Lockheed Martin uses "fifth generation fighter" to describe the F-22 and F-35 fighters, with the definition including "advanced stealth", "extreme performance", "information fusion" and "advanced sustainment".[2] Their definition no longer includes supercruise capability, which has typically been associated with the more advanced modern fighters, but which the F-35 lacks.[9] Lockheed Martin attempted to trademark the term "5th generation fighters" in association with jet aircraft and structural parts thereof,[10] and has a trademark for a logo with the term.[11]


Bye, bye supercruise. Prof Das totally missed that?


No. In fact Das has not missed that at all - you have missed it. Das questions the need for supercruise in the article

Here are Das's arguments against supercruise for AMCA and as you point out the Americans seem to have discarded it, changing the definition from what it used to be
Supercruise cuts the transit time by half. However the FR tankers barely do 400kts. The 5th generation aircraft will require refuelling every 70-80 minutes or so. What will be the effect of the frequent hook ups on super cruise gains, Sir!? To remember is that super cruise will need the most advanced technology of engines available only to the West.


Also he asks
1. Unlike ordinary “supersonics”, a super cruiser will ‘soak”. Its skin will soak at 125 °C whilst the core structure may be at - 65° C. How does one attach a composite skin to metal structure both having widely different co efficient of expansions reliably so that in service stealth, is not affected. I am emphasizing this because the LCA is supersonic for a few minutes at best and will not “soak” as the AMCA skin will.

2. Because of the high skin temperatures of 125⁰ C stealthiness is compromised to IR scans. The trick is to cool these areas using coolants or fuel. What is the standard of preparation on this as far as laboratory work is concerned? Same with cooling of the jet efflux.


Does the AMCA need supercruise?
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby shiv » 09 Sep 2015 08:45

NRao wrote:As I have stated, umpteen times, to be on the very leading edge, one has to have people who will take humongous risks.

NASA is actually reviving that culture - to take huge, huge risks.

IF India wants to be a "power" of any sort - even in the IOR - India better start taking larger risks and not be cowered down by failures.

Supercruise for AMCA is a huge risk. Should India take a risk that the US has now given up?

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby NRao » 09 Sep 2015 09:30

Man! In a PC world it is very difficult to post anything, but let me say this I just do NOT consider Das to be normal. IMHO he is very confused - to say the very least without getting fired for it.

On the topic:

Then you introduced the confusion, here is your post from the other thread:

shiv wrote:When we speak of generations, does anyone have any quibbles with Prof Prodyut Das' definitions? If so what are the objections
http://profprodyutdas.blogspot.in/2015/ ... p.html?m=1

.........................................................


It implies Das has a position on "5th Gen" and it includes SC.

(And way down in his "article" he suggests using a MiG for SC!!!!!!!!!!!!!! Why? Why even suggest? Silly.

Here are Das's arguments against supercruise for AMCA and as you point out the Americans seem to have discarded it, changing the definition from what it used to be


Two things:
1) I have no idea what all this about. I do NOT care what Das says.
2) People have to conduct some research, if you or Das do not then we always come up with Turkey and Albatross related threads. Waste of time.

So here is the research:

The US/Americans has/have NOT abandoned SC. LM has decided to rebrand their version of the 5th Gen for the F-35 - simple as that (BTW, the F-35 is a totally diff animal)(Das will not get it). The problem is that you are introducing your biases into discussions. There is a huge diff between "US"/"Americans" and "LM".

The US has decided to retain SC in the 6th Gen plane. Will LM climb on that bandwagon? TBD.

Also, the CAS has specified SC, not me or anyone else on BR. And, he has provided a reason too. So, what is Das' problem as it relates to the CAS? why all this pontification on SC and no acknowledgement of what the CAS stated? He can disagree, but to totally ignore what the CAS stated and then hammer away is cheap.


Supercruise for AMCA is a huge risk. Should India take a risk that the US has now given up?


Who says SC is a "huge" risk? Can you defend that? And please do not come back with Das. Not an answer at all. And what is NOT a risk - crossing a road is a risk. How huge is TBD.

Also, if the IAF has identified a need, what does it matter if the US keeps it or not. the question then becomes tech, cost, ROI, etc.



And, please do me a favor and keep Das out of these AMCA discussions. As far as I am concerned I am not sure why the editor of that mag did not do a better job.

SC for ferrying!!!! As though there is nothing else that SC can be used for. How cheap is that?

I am glad Das is flying stealth and he does not appear on my radar. Please keep him out.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby shiv » 09 Sep 2015 09:46

NRao wrote:
Supercruise for AMCA is a huge risk. Should India take a risk that the US has now given up?


Who says SC is a "huge" risk? Can you defend that? And please do not come back with Das. Not an answer at all. And what is NOT a risk - crossing a road is a risk. How huge is TBD.



First let me define "risk". Risk is the probability of occurrence of an adverse event that, in the case of aircraft development, might lead to great delays or cancellation, or changes in plans not originally envisaged.

What is the risk that AMCA might not not fly at all? What is the risk of that? I would judge that as a low risk

What is the risk that the AMCA will get delayed? I think the chances of this risk depend on what India chooses to do.

We have no engine as yet. The engine is crucial to supercruise. Another crucial factor is weight and drag caused by the skin and the quality/content of the stealth coating. Rivets, welds, seams, bumps etc may cause issues retarding range, fuel consumption and the ability to supercruise but we will never know until we have the engine in place.

So let me get back to the fuzzy "everyone is correct no matter what he says" definition of 5th generation and what AMCA is supposed to have

AMCA is supposed to feature
1. Stealth
2. Supercruise
3, Thrust vectoring
4. Sensor fusion

I see supercruise and thrust vectoring as big risks that will delay the project. I would be far happier to see the AMCA have stealth and sensor fusion and leave supercruise to some future date. Thrust vectoring I will not speculate about. So far as my knowledge goes thrust vectoring either involves the engine nozzles themselves (eg Al-31) or some ducts or vanes that are not integral to the engine nozzle. the latter may be feasible, but it all means nothing until an engine appears.

Supercruise is an unnecessary risk.

Your views of Das are your views and my keeping him out will not prevent his articles from appearing and being read in Aviation journals. Ignoring what is inconvenient is not a solution in my mind.

NRao
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby NRao » 09 Sep 2015 09:53

What is a relevant necessary risk?

Do you deal with "risk"?

The stuff about crossing teh road was not about Das, but to specifically keep Das out of the picture.

Oh, now you changed your post.
Last edited by NRao on 09 Sep 2015 09:57, edited 1 time in total.

NRao
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby NRao » 09 Sep 2015 09:56

Your views of Das are your views and my keeping him out will not prevent his articles from appearing and being read in Aviation journals. Ignoring what is inconvenient is not a solution in my mind.


Das has ignored. And come up with his own universe, srishti.

And, true about appearing in aviation journals. Guess everything slides after a while.

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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby brar_w » 09 Sep 2015 14:29

i.e This was an American definition back then and as you have pointed out, the Americans have changed their definition. Here are Das's arguments against supercruise for AMCA and as you point out the Americans seem to have discarded it, changing the definition from what it used to be


The problem arises when Das and others fall into the "defining 5th generation trap". The Americans defined the ATF and they defined the JSF/JAST. They did not set in stone definitions for what a 5th generation fighter should be as in if it does not fall within some imaginary defined parameters then it is not 5th gen. That side of the argument is totally unnecessary. You can design a subsonic (irrespective or afterburner usage) stealth aircraft and call it 5th generation and you will be as within your rights to do so as someone else that can cruise at Mach 1.8 and has stealth. Ultimately, its a next generation weapons system designed to counter some of the challenges that warrant it, not some preordained set of capabilities that come from a menu. Unless Das can claim otherwise there is no proof that the IAF or AdA chose the supercruise requirement for any other reason besides it being tactical usefull to how the AMCA is expected to conduct its mission.

Does the AMCA need supercruise?


Neither you, nor I nor anyone apart from those that are privy to details on its expected mission requirements can answer that question.

Here are Das's arguments against supercruise for AMCA and as you point out the Americans seem to have discarded it, changing the definition from what it used to be


The definition of supercruise as a requirement came into the ATF. The Americans did not discard Supercruise from the JSF because it was not required but because it was traded away for other design considerations. Aircraft designs begins with mission requirement design and development, and you try to give a large trade space to the designers but in addition to that you also give them requirements that they can meet while staying on the affordability path that usually comes from the number of aircraft you are required to procure. This is the reason as to why the F-16 for example is an inferior BVR aircraft when compared to the F-15, even though it came into service after the latter was designed. The design changes required to make an F-16 better at BVR would have involved having it perform better in the 50,000 Feet + envelop, add more supersonic radius, have it carry a significantly larger radar, give it more room internally for EW/EA payloads etc etc. All these design changes would have made it as good in BVR combat as the F-15C but would have also made it unaffordable given the quantities that were ultimately produced.

In the JSF It was technically very difficult to design and build affordably a single engined, strike fighter that could carry a much more flexible and larger payload (2000 lb vs 1000 lb bomb carriage for F-22) than the ATF requirements, fly longer subsonically (a program requirement), and conduct Strike sorties from medium altitudes (as opposed to the F-22's operational altitudes) and yet still meet all those requirements with supercruise in mind. The only thing that can change those realities is the next generation of engines but those are still some time away. There is a thesis I posted a while back that looks at the exact cost of supercruise in $ amount when all the design details are factored in. Supercruise was deliberately left out in the jSF because it would have resulted in (unless other specifications were changed (such as range, payload, cost etc) a larger, more heavier fighter that would be considerably more expensive thereby making it tough to replace thousands of F-16's and F/A-18's (and Harriers and A-10's). A consequence of doing away with the supercruise requirement was that the designers could design for much better stealth both from the RAM (FiberMAT) given that it need not be subjected to intense supersonic environment throughout its operational life as compared to the F-22A (therefore higher composites on the frame and baking the RAM directly into the structure) and also design for structure degraded (dings, scratches and airframe damage) performance that could still meet RCS which would have been quite costly had it been in addition to supercruise.

Whether those constraints exist on the AMCA can only be known to those that are familiar with the program requirement details. Even if we go back to the ATF, Stealth and Supercruise were the 2 key design features required to be survivable in its operational context (with the most important actually being LPI sensors as the video I posted in the International thread explains). If you loose the supercruise requirement you would almost certainly have to have much better stealth to be equally as survivable. (Electronic warfare and EW protection comes to all so I am not going into those fields because they are complicated from a counter capability pov)

I too have/had reservations on supecruise when I first looked at some of the news reports (posted here) on the expected internal payload and MTOW values and then the engine options, but there are many considerations on top of that that could still make supercruise easily achievable if the designers are willing to do the trades to get it. As far as TVC is concerned there are 3 options (as far as I am aware) that would be available depending upon the engine selection process -

1) EJ200 derivative engine with production and/or TOT on the Spanish 3D TV Nozzle
2) GEF414 derivative engine with production and/or TOT on a modified GE AVEN (offered to Sweden for the Gripen as far back as the mid 1990's)
3) Co development of a new clean sheet nozzle with the help of Russia for either of the above mentioned engines (or a Russian Engine)

Either way, TVC does not have to exist from the start but can come in later. Supercruise as well but ideally you would want to have it as a requirement from the start unless you want to rely totally on propulsion advances to carry the day.

NRao
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Re: Is the AMCA a pipe dream that will become a dead Albatro

Postby NRao » 09 Sep 2015 20:26

This is perhaps the simplest explanation of SC I have come across:

The core purpose - the one that the CAS expressed too:

Supercruise has a singular purpose; to increase the speed of the aircraft's transit to and from the target zone without sacrificing range by dumping fuel into the afterburners at ten to fifty times "military power"


It is not about efficiency during ferrying the plane (I have not come across any thing that suggests it. I think it is something that Das imagined?), etc. Also, it is not about cruising for long periods of time - as in hours - it is more like 20-30 minutes, if at all.

It's less about the engine and more about the combination of engine and plane. Theoretically, all that is needed is for the engine(s)' thrust without afterburners to be able to overcome the plane's inherent drag at a speed greater than Mach 1. Simple, right?

Well, to do that, you're up against some pretty heavy physics. First and simplest, given a drag coefficient for the aircraft in a "clean" configuration, the drag force increases on the square of velocity. So, to go twice as fast, you need four times the thrust with all other things being equal. Jet engines simply don't scale that way; you need a bigger engine to provide more max thrust, and then all things aren't equal anymore.

Second, planes aren't built like cars, where in many cases there's enough room under the hood to drop in a bigger engine block and a turbocharger to double power for negligible additional weight. Fighter designs have to essentially wrap an aerodynamic skin as tightly as possible around the pilot, engine, avionics and fuel storage. For the longest time, engine efficiency was pretty static, therefore more thrust meant more engine. A bigger engine means a bigger plane, which means more drag, which offsets the thrust gains and thus the speed increase of the larger engine.

Thirdly, there are some complex aerodynamic changes involved as a plane transitions the sound barrier. Airflow into the engines increases at higher speeds, which reduces the compression ratio of the engine; the intake turbines become less and less efficient as speed increases, and thus you get less and less benefit from the "bypass" airflow of the turbofan. Afterburners are more or less a simple way to continue to get more thrust after the intake turbines are no longer significantly compressing air, by taking that air, dumping a bunch of extra fuel in it and riding the prolonged explosion. This, however, uses ten to fifty times the aircraft's cruising fuel flow rate.

The F-22 achieves supercruise in part by extending the efficient operating range of the engines with "variable bypass". At lower airspeeds, engine bypass is increased to allow the turbofans to increase thrust with minimum fuel. At higher airspeeds when the turbofan effect decreases, compressor bypass is reduced to put more air into the combustion chamber (along with more fuel), which increases thrust beyond the normal compression limit more efficiently than simply burning the bypass airflow with an afterburner.

Finally, there is the simple requirement of supercruise in an aircraft's mission profile. Not many things in air combat occur at supersonic speed; you can't dogfight effectively at Mach 1 because your sustainable turn rate is measured in miles, you often can't drop gravity ordinance (bombs) because they won't fall away from the aircraft in a stable or predictable way, and in the case of the Raptor you have to open payload doors to deploy your weapons and that will increase your drag right there.

Supercruise has a singular purpose; to increase the speed of the aircraft's transit to and from the target zone without sacrificing range by dumping fuel into the afterburners at ten to fifty times "military power". For an air superiority fighter (combination interceptor/dogfighter), that's very important, but the F-22 was the first U.S. fighter developed from the ground up to take advantage of the latest technological progress in aircraft design such that it could be achieved. The last time U.S. fighter designers got an opportunity to design a "cost-is-no-object" superfighter was almost 40 years ago with the F-15, and the two major fighter designs to enter U.S. service in the interim, the F-16 and F/A-18, were the result of a design competition specifically intended to create a lower-cost multirole fighter to serve as the bulk of the air fleet


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