JayS wrote:- We don't have marine requirements, which is the most restrictive of all. So lets drop it.
Corrosion requirements and hard landing issues would remain, for jump jets.
- Hard to believe Naval version would have restricted length and weight when they wanted a twin-engine jet which would have been invariably longer and heavier. I have not come across any reference stating so. If you have please share.
A lot of these links are no longer available, I'll need to look under my own posts. But the basic issue were a whole lot of changes around wing size, requirements, around dimensions for a Naval jet (it had to be sized to fit Naval hangars and elevators, and decks) which were far more restrictive than those for a CTOL AF fighter. The CV wing had changes to its design for low-speed approaches etc. Again, this has had issues elsewhere or contributed to it.https://breakingdefense.com/2013/08/don ... sue-fixed/
What happened? Basically, new algorithmns were written, tested in the trans-sonic envelope where most of the problems occurred and the services found a solution that didn’t completely eliminate all drop at all times but left the plane performing to the highest standards achievable. In short, they found a problem and fixed it to a standard all three services could live with.
Brilliant PR speak and how we really need to learn from the US MIC in how they "message" their problems away. In short, it remains, and a concession has been given. Note how we belly-ached about the LCA in comparison.https://www.vanityfair.com/news/2013/09 ... eed-martin
To turn its X-35 prototype into a fleet of F-35 fighters, Lockheed has relied on two seemingly separate but equally controversial acquisition practices. In military jargon, these are known as “commonality” and “concurrency.”
Commonality simply meant that the three F-35 variants would share portions of high-cost components like the airframe, the avionics, and the engines. This was supposed to help ensure that the plane was “affordable”—a term that the company and Defense Department managers invoked with the frequency of a Vajrayana chant. But commonality did not really come to pass. The original plan was that about 70 percent of all the parts on the airplanes would be common; the actual figure today is about 25 percent. Commonality, even at this reduced level, has unintended consequences. When a crack in a low-pressure turbine blade was discovered in an air-force F-35A engine earlier this year, Pentagon officials took the only responsible course, given that the part is used in all models: they grounded the entire fleet of F-35s, not just the ones flown by the air force. In his June testimony, the Pentagon’s Dr. Gilmore revealed another, less public grounding of the entire F-35 test fleet, which occurred in March 2013 after the discovery of “excessive wear on the rudder hinge attachments.”
From the outset, Lockheed assured Pentagon officials that technological innovation, including heavy reliance on computer simulation, which could take the place of real-world testing, would keep costs down. The Pentagon bought those assurances and allowed the company to design, test, and produce the F-35 all at the same time, instead of insisting that Lockheed identify and fix defects before firing up its production line. Building an airplane while it is still being designed and tested is referred to as concurrency. In effect, concurrency creates an expensive and frustrating non-decision loop: build a plane, fly a plane, find a flaw, design a fix, retrofit the plane, rinse, repeat.
Vice Admiral David Venlet, who managed the J.S.F. program until late last year, acknowledged the absurdity in an interview with AOL Defense: “You’d like to take the keys to your shiny new jet and give it to the fleet with all the capability and all the service life they want. What we’re doing is, we’re taking the keys to the shiny new jet, giving it to the fleet, and saying, ‘Give me that jet back in the first year. I’ve got to go take it up to this depot for a couple of months and tear into it and put in some structural mods, because if I don’t, we’re not going to be able to fly it more than a couple, three, four, five years.’ That’s what concurrency is doing to us.”
Re: Naval use LM had to change its entire RAS approach and that too needed time consuming testing. Again, trying a "common approach" for all problems.
Having built the F-117A Nighthawk and F-22 Raptor, Lockheed Martin has plenty of experience with the highly toxic coatings and svelte surfaces that help stealth aircraft go undetected. The company also knows that the technology is finicky and has the capacity to turn a cutting-edge fighter into a hangar queen. A significant portion of an F-22 Raptor’s downtime is spent in hangars with maintainers mending its stealthy coating, which has a tendency to wear off during certain meteorological conditions.
When the time came to cover the F-35 with a radar-absorbing material, Lockheed changed its technology, covering the plane with a rigid coating applied in sections. Unfortunately, prolonged use of the plane’s afterburners causes the F-35’s stealthy outer layer—as well as the skin underneath—to peel and bubble near the tail. As a result, the F-35 is prohibited from supersonic flight while Lockheed Martin comes up with a fix—one that will require retrofitting the 78 planes that have already come off the production line. The fact that this could have occurred at all, much less on the Pentagon’s biggest and most important weapons program, baffles Pierre Sprey. “Everyone knows that the faster a plane goes, the warmer the skin gets,” he says. “All they had to do was test a one-square-foot portion in an oven. Yet again, we’re finding this stuff out on planes that are already built.”
When asked how two signature elements of the same program—stealth and supersonic speed—could have come into such direct collision, a senior Pentagon official with access to F-35 test data explained, “This is not rocket science. When you let a contractor do whatever he wants to do, and you don’t watch him very carefully, he’s going to trust his engineering analysis as opposed to doing what you just said—building a piece and putting it in an oven. Because he looks at a piece of paper and he’s got his engineers and he says, ‘Oh, this is good; we’ve got margin there. We’ve got an extra 10 degrees and an extra five minutes on the coatings. We’re good. We don’t have to test that.’ Government oversight would say, ‘Show me.’”
This is the guy who ran the program itself
A more disturbing assessment came from perhaps the most improbable source: Christopher Bogdan, the general who heads the Joint Strike Fighter program. A few weeks after I saw him in Norway, we sat down at his office in Crystal City. The plate-glass windows offered views of the Jefferson Memorial and the Washington Monument, and if Bogdan had been wearing a dress uniform with his ribbons and his three stars, the scene would have looked like a cartoon or a cliché. But Bogdan, 52, wore a green flight suit. He too is a pilot, one who has logged 3,200 hours in 35 different military aircraft. When answering questions, he frequently thumped his fist on a conference table.
With dry understatement he took issue with the bedrock concept of the Joint Strike Fighter—that a single airplane could fulfill the different missions of three different services—calling it “a little optimistic.”
This is from Defense News in June 2019 about continuing problems:https://www.defensenews.com/air/2019/06 ... -problems/
Context - she is the author who did this NYT piece in August (basically not their usual crappy journos, so quotable)https://www.nytimes.com/2019/08/21/maga ... ogram.html
There soon turned out to be an essential flaw in the grand plan for a single plane that could do everything. Design specifications demanded by one branch of the military would adversely impact the F-35’s performance in another area. “It turns out when you combine the requirements of the three services, what you end up with is the F-35, which is an aircraft that is in many ways suboptimal for what each of the services really want,” said Todd Harrison, an aerospace expert with the Center for Strategic and International Studies. “It is much more expensive than originally envisioned, and the three versions of the plane actually don’t have that much in common.”
But early in the program, Lockheed Martin began construction with glowing optimism. The company decided to build the Air Force’s F-35A first because it was considered the simplest model, then move on to the difficulties of the F-35B short-takeoff and vertical-landing version and then the F-35C, which can land on an aircraft carrier — a decision that turned out to be a mistake. Once Lockheed’s engineers proceeded with the more demanding design of the F-35B, they found that their initial weight estimates were no longer accurate and the B model was on track to be 3,000 pounds too heavy to meet specifications. The company was forced to begin an extensive redesign project that added an 18-month delay to the program.
- F35 has a decent length for a single-engine jet. The longer length would have increase empty weight, screwing the performance for a given engine for AF version too. I don't understand why would the USAF want a longer version unnecessarily. And if the requirement was so overwhelming, I am sure LM could have found a way to add fuselage plugs in the common design for AF alone, given AF requirement and export potential for it is the largest.
They weren't looking at just longer lengths but overall dimensions. LM was also having to manage cost impact for the fighter. They were under severe pressure to manage the overall cost/airframe and cost/program so obviously, it was in their best interest to reduce significant redesign/platform. However, as testing progressed those very limitations have come back to bite them as system complexity has increased.
In an article that Bloomberg News publishes on August 31, 2007, it is announced that Lockheed Martin is exceeding the budget on the first phase of the Joint Strike Fighter program. The manufacturer warns that the reserves will be spent by the end of 2008, unless cuts are made. Lockheed Martin is seeking US Defense Department approval to lessen the number of test aircraft and personal plus hundreds of test flights to save money, and replenish a reserve fund.
Or this:https://breakingdefense.com/2011/12/jsf ... st-slow-v/
- If you ask me, its the Navy who has done compromises not the other way round. Diamond wing is not the best solution for Approach/landing aero. While Rafale could manage with the exact same wing-canard combo for both the application (actually Rafale's exceptional ability of MTOW being 2.5x of its empty weight is the result of its design for very slow landing/approach speed for deck landing) (and similarly, F/A18, Su33, MiG29K have LREX to help in approach/landing), F35 needed a slightly different solution. LM sorted out the issue by having a larger wing created using inserts of larger size in the common wing structure. From what I know there are no severe restrictions on F35's landing weight. So this solution works.
That's the whole point, all 3 services are having to make compromises and these compromises are sub-optimal. As it is, fighter design is all about trade-offs, so why would you wish to add service specific trade-offs on top of it? This has the same issue we saw with the LCA, i.e. limiting it to MiG-21/LWF dimensions then adding more and more MR requirements derived from larger aircraft. What I mean is one compromise at one point ends up causing a lot of issues elsewhere.
LM keeps bragging about how great their packaging is, their critics pointed out they were making a virtue out of a (necessary) vice given there literally was no space to manage conventional answers given the contradictory requirements of stealth/heat management & volume taken up by an internal weapons bay.
Why go this path at all? Whether this issue or the concurrency, both were flawed decisions from the get-go.
- the strengthening of structural components for naval application is done through simply using a concept called Cousin parts - you thicken the AF version parts or replace Aluminum with Titanium for additional strength. This has greatly reduced time and effort in design and development. This does not burdon the AF variant any more than a separate design would have. AF version stays lean. Even in case of Rafale, the commonality in aerostructure is 80% IIRC. Did Rafale M burdened Rafale C's performance..? It did not. The Rafale M weighs 650kg more and is less maneuverable. But the AF version has no restriction. In fact, it has better payload and range capabilities on account of better aerodynamic capability from the M version. This while maintaining 80% structural commonality and 95% system level commonality. Arguably, Rafale like solution was not feasible for 5G given design implications due to stealth requirement, but there is no particular reason why F35C's approach could not have worked.
I am not sure the cousin parts approach is the only issue here. Its not merely the structural parts, its also the avionics, the actuators, the hyrdaulics, all the associated subsystems which all need to be tested and re-qual'ed for the Naval environment. The alloys will need to be tailored, the coatings, paint, everything ends up with an additional test margin, cost impact, timeline impact. In the JSF for instance:
Fatigue testing has barely begun, Venlet said. The CTOL variant’s fatigue testing is about 20 percent complete; the CV variant has not started yet. For the STOVL variant, fatigue testing was halted at 6 percent last year and has not resumed after a crack in a large bulkhead in the wing was found, requiring a major redesign of that part.
- AMCA is already twin-engine and having the engines which Navy would anyway use.
Yes, use the AMCA as a baseline but then ditch or change what the Navy doesn't need or want.
- Of course there is always a cost for commonality, but then there is a cost for separate development programs as well. GIven Navy's smaller requirement, I feel cost of commonality is lower than cost of fresh new design. We are not going to import any of these jets. IAF might be interested in de-navalised version. But if they get 114 MMRCA 2.0 and later AMCA at hand, I wonder how much they might want, when it doesn't offer much unique capability and neither it is cheaper given small number. Wouldn't they simply buy more AMCA..??
TBH, when I look at cost, its a no-brainer that it works out for us, despite any additional costs (I did some rough calculations on how much we provide to Indian industry). The main "costs" I perceive in our context "user acceptance" and "timeline". These are two of the main challenges I see we grapple with in our local context. If for whatever reason our answer is 80% as versus 90%, it attracts horrible criticism from the services, massive leaks calling it junk, and if it is delayed, the oush for an import begins. These are invariably due to too many complex requirements expected out of contradictory specifications and inexperienced team/limited local support, add budgetary woes. This is the main reason I'd prefer a design optimized and run by each service which *they* own and can manage to their needs as versus grimacing that the IAF is getting x specification which will affect Navy's Y requirement or the IAF grimacing that to keep design "straightforward" some compromises were made to their awesome air superiority jet which can no longer accelerate as fast as the latest PAK-FA offered by the Russians etc.
I have spent considerable time on this matter. I think we could have made AMCA in such a way that it could have easily (relatively speaking) been navalised when need arises. And I dont mean exact same fighters for both applications, making AMCA design in such a way that parts needing modifications for Navalisation would be drop-in fit post-modification, without having to change rest of the structure too much or at all. For example, placing MLG attachment points such a way that they will not need change for Naval version. And this is not a big thing really to expect. AMCA being twin engine, already makes things easy.
I think you misunderstood me. I dont want exact same fighters for IAF and IN. Neither F35A and F35C are exactly the same. The commonality is less than one would expect.
I dont want to justify or oppose the decision anymore. I just want to understand it. I will make my arguments only to invite counter arguments which might help me understand the situation better.
Fair enough, I have a very simple approach to this whole thing. Just look at our limitations and context. I do know that w/o Parrikar sir's intervention the NLCA was a no-go. The Navy literally pulled the plug on the program. Given that, I won't be surprised if IAF was the "only game in town" for AMCA and they went with the one customer they had, as versus trying to delay things waiting for Naval approval and adding to possible delay by trying to incorporate Naval needs. The initial AMCA work was done out of DRDO's own seed money, as the GOI didn't release formal funds till later.
I also don't think the AMCA naval modification would be straightforward, because several of the sources i did read on the JSF made it clear that the LM guys were pushing back on the platform specific changes because of budget issues. I'd rather we had separate programs budgeted separately! Look at the number of unique parts and cousin parts here - why even bother with this approach, as versus clean-sheet optimization.
In our case, the Navy may say, the TEDBF has to be within the following dimensions based on our ship envisaged capabilities, fit the following elevator with folding wings, have this level of stealth (because with corrosion can't manage more than that), we are stressing on range/payload, reliability, we need low speed handling able to manage the carrier deck, quick stop etc.
IAF may say - relax these and focus on kinematics for BVR, focus on broadband stealth - we are up against IADS, we need avionics completely integrated with AWACS and IACCS..
I mean why compromise one set of requirements to manage the other. Our programs are dirt cheap compared to worldwide ones. We don't face their budgetary issues with program costs, but we start from a lower baseline of experience, subsystem availability and managing optimization. In which case we are better off de-risking our programs by making them simpler and tailored for each service in particular, rather than adding complexity by making them capable of anything.
Take RAS for instance, suppose we have a system capable of IAF use but not Naval use, and which needs a certain manufacturing process which AF is willing to invest in. By keeping programs separate and costed separately, you can go ahead with the IAF one & stop worrying about making a single answer suitable for both AF and Navy.
See this for instance, from 1997 about the B-2 - just pointing this out for instance, about the kind of issues faced when dealing
WASHINGTON -- Two years ago ('95), the problem with the Air Force's B-2 Stealth bombers, which cost $2 billion apiece, was that their radar could not tell a rain cloud from a mountainside.Now the problem is that the B-2 cannot go out in the rain.
The investigative arm of Congress reported this week that the B-2, the world's most expensive aircraft, deteriorates in rain, heat and humidity. It "must be sheltered or exposed only to the most benign environments -- low humidity, no precipitation, moderate temperatures," said the report by the General Accounting Office.
Now, a decade later, from 2009http://www.washingtonpost.com/wp-dyn/co ... 03020.html
The aircraft's radar-absorbing metallic skin is the principal cause of its maintenance troubles, with unexpected shortcomings -- such as vulnerability to rain and other abrasion -- challenging Air Force and contractor technicians since the mid-1990s, according to Pentagon officials, internal documents and a former engineer.
Point being, you may need to change things entirely for an AF approach
to a problem versus a Naval one
. Your AMCA are going to be most of the time in hangars or on AFB, shielded from the elements, whereas the Naval TEDBF may be exposed on the deck.
So AMCA may be able to get by with stealth & RAS, and limited EW but Naval fighter may take an entirely different approach and focus more on payload including EW to fight its opponent.
Similarly, IN is very pragmatic about using imported subsystems. If program costs shoot up, and they need specialized gear, for a low production run in TEDBF you can always import. Indigenize over AMCA..
Just pointing out there are dozens of small decision points which can add up over time.