mattIf you built a MiG-25 with modern technology, you’d call it a MiG-31 (or MiG-31M if it was even more modern) 😀
LMAO! best answer out the bunch..
GLAD YOUR BACK
🙂
mattThe IRBM threat is not the only thing, they have to worry about Katshuya rockets as well i suppose. I swear ive read some place that isreal has a laser system in place that can destroy a Salvo of rockets before they do any harm.
mattBut to take carbon fiber for an example, yes it has huge strength propertys, as much as 20 times as strong as steel. Its also very flexible. However its molecular structure is very rigid and so the material simply breaks when any kind of load other than the direction its was designed to hold is given. Thats why composites are either used as a strengthener to conventional materials or are used in non load bearing structures.
Hey that was an interesting read..but just to nit pic, most IM graphite/epoxys dont even come to matching the strength of steel. If you are talking specific properties then yes, they (of of them and depending on the plane) better steels properties but. they dont come close to matching steel for strength. maybe the newer diamond coated fibres, or when nano tubes come into play but thats way to many years from now it seems.
mattdo the have a base near Kashan ? (excuse the spelling)
mattI felt bad, so posting this :'(
Not really much detail, DJcross has done a pretty good enough job, theirs lots more though..and you cant cover it on this forum, i suggest picking up some books.
Mechanics of composite materials by R, JONES would be a VERY VERY good start.
The mechanical engineering handbook might also provide a insight, with composites its never clear cut.
The usage has to be considere very very thoroughly, even boiling down to the type of composite you decide upon.
Composites in combat
Lon Nordeen sees the day when the all-composite combat aircraft will become a reality.
ONE OF THE IMPORTANT applications of technological progress to modern aircraft is the use of composite materials in their construction. Moulded into an epoxy resin matrix, they have produced extremely tough and stable materials that are replacing aluminum and aluminum alloys. This has a significant effect on performance, weight, design and cost.
Advances in technology have had an enormous impact on the shape, performance, reliability and composition of modern aircraft and fly-by-wire flight control systems (FCS) and sophisticated avionics suites have enhanced the utility and performance of military aircraft dramatically. Propulsion systems also have improved and advances in structural technology have influenced the way military aircraft are designed, produced and maintained.
Until the late 1960s, almost all tactical aircraft were composed primarily of aluminum and its alloys. High-speed aircraft such as the Lockheed SR-71 used a sizeable amount of titanium, but high cost and the demanding production requirements of this material limited it to moderately high temperature applications. Consequently the latest tactical aircraft incorporate many non-metallic composite materials. Sixteen per cent of the structural weight of the Boeing F/A-18E/F and Lockheed F/A-22 are made up of about 20 per cent composite material while 26 per cent of the AV-Harrier II’s empty weight is composite structure. Future military aircraft such as the F-35 joint strike fighter are expected to have a composite content of at least 35 per cent.
Composite material is made up of two or more separate components that when combined result in property changes that differ from the original materials. Composites most widely used in combat aircraft are composed of high-strength fibres of glass, boron, plastic or carbon that are embedded in an epoxy resin matrix. The fibres have very high strength, a uniform structure and lack flaws. The epoxy resin bonds with the fibres in the curing process to produce an extremely tough and stable material.
The most widely used composite material in tactical aircraft is a carbon fibre/epoxy mix. Carbon epoxy has eclipsed boron-based composites because it is much cheaper to produce, easier to machine and drill, and can be formed into complex shapes to produce structural members such as spars and ribs. Other fibres typified by Dupont’s Kevlar also are being used in aircraft production. Kevlar is less dense than carbon fibres but has inferior mechanical properties. It is used in pressure vessels, for ballistic protection and as lightweight fibreglass non-structural parts.
Composites have displaced conventional materials such as aluminum because they have several advantages. They have lower density and greater strength and stiffness than aluminum, therefore a smaller lighter structure can carry the same load. Studies conducted by Boeing indicate that a 38 per cent composite structural weight can result in a 40 per cent reduction in empty weight, 39 per cent reduction in wing area and a 33 per cent fuel saving for the same mission profile when compared to an aircraft of conventional metal structure.
Another big advantage is that composites are relatively insensitive to flaws. Fatigue testing of composite structures demonstrated their high resistance to cracking and that fractures generally do not propagate. Composite materials are very stable and so are not subject to corrosion as are metallic structures. However, in the design process, careful attention must be paid to composite/metal interaction because through galvanic action some metals will corrode when in contact with carbon fibre/resin laminate.
Design impact Composites have had a significant impact on the design process. Metal parts start as a solid piece, usually machined down to a specified size and thickness. Multiple parts are fastened or riveted together to form structures. Using composites, a designer has much greater flexibility because the strength and stiffness of structures can be tailored. The material can be stacked with one ply running in one direction and the next at a 45 or 90-degree angle.
To increase strength or stiffness in a localised area, a larger number of plies may be overlaid, each with a different shape and orientation. Tailorable strength enables designers to optimise aerodynamics such as in a forward-swept wing aircraft design. The weight of metal structures would prohibit such a prospect. Beech Aircraft is filament-winding entire business aircraft fuselages and the Vantage business jet is an all-composite aircraft. These new technologies also are expected to be incorporated into military aircraft and missiles.
Metallic fasteners, leading edge sections, spars and honeycomb materials can be combined with composites to form very strong and lightweight structures. Carbon epoxy composite materials are cured at up to 350o and pressures of up to 150lbs/in2. This changes the epoxy in the material from a soft resin to a hard, strong, solid material.
However, composites do require new skills. Design, production and quality-control personnel have had to adjust to the way they operate in order to take full advantage of the potential of these materials and to produce it economically. The computer has been a major ally in the move to composites. Computer-aided design (CAD) has made it much easier to develop composite structures and to understand their relationship with other elements of an aircraft more thoroughly.
Labour was one of the largest expenses in early composite fabrication. Lay-up time was long, production man-hours high and there was a sizeable amount of wasted material. CAD has assisted production planners in making efficient use of raw materials. Highly automated composite lay-up machines developed by Boeing and Vought for use in producing the B-2 stealth bomber, have set the standard for size and speed. Computer-controlled laser, water-jet and knife cutters and inspection machines have speeded the production process, increased efficiency and reduced the cost of composite fabrication.
Non-metallic parts have required the development of new testing and quality control techniques. After removal from the autoclave, composite parts are examined for flaws with computer-controlled ultrasonic and x-ray equipment. A recent advance pioneered by Lockheed Martin are the Laser ultrasound testing systems that are much faster and more accurate than older, water-based systems. Computerised design, production and quality processes, learning curve benefits and increased competition have reduced the cost of composite parts significantly.
Research has shown the potential of a wide variety of new composite materials, carbon and graphite fibres have been combined with a matrix of metal rather than epoxy. This material has improved strength at higher operating temperatures than current widely used resin matrix composites. Hot sections, such as engine exhaust, are a unique composite application.
Carbon-carbon applications were designed for the National Aerospace Plane (NASP) programme, a technology now being pursued by engine companies. Ceramic matrix composites are an alternative material also being developed for high temperature applications. However, these technologies have yet to be perfected, they have proven to be brittle and difficult to fasten together.
Fibrereinforced thermoplastic composites produced by melting resins and combining them with re-inforcing fibres under high pressure in a mold, are another promising new area. Tests have shown these composites to be highly resistant to damage, able to be reshaped and quickly fabricated. Compared to carbon epoxy, fibre-reinforced thermoplastics are equal in density, equivalent in strength and part production may be less expensive. The USAF and several other air arms, material suppliers and a multitude of contractors are developing thermoplastic composites.
One area where composites have a significant advantage over most metallic structures is in radar cross-section reduction. Composites generally reflect less radar energy than metallic structures and advanced composite materials offer this benefit with structural, heat-resistance and configuration advantages. Aircraft can be formed with smoother lines, fewer areas where different materials merge and in complex shapes required for reduced signature requirements. The F/A-22, B-2, F/A-18E/F and unmanned aerospace vehicles such as the X-45 UCAV include a significant amount of composite materials.
Tactical aircraft now in advanced development in Europe also incorporate a sizeable amount of composite materials. Eurofighter’s Typhoon makes extensive use of carbon/epoxy material, as does the Saab Grippen multi-role fighter. Composites account for about 25 per cent of the Dassault Rafale’s structural weight with boron, carbon and Kevlar composites used in its front and centre fuselage sections, integral fuel tank, lower rear fuselage, wing, canards, rudder and many access panels.
Boeing recently unveiled its Bird Of Prey aircraft that was designed, built and tested in the 1990s as a demonstrator for rapid prototyping and advanced composite concepts. McDonnell Douglas, that merged with Boeing in 2000, self-funded the $67m programme to provide design engineers, production personnel and pilots an opportunity to test new concepts. Another goal of the programme was the testing of low-cost disposable tooling, rapid prototyping and 3-D virtual reality design and assembly.
The strike fighter design featured a low observable configuration with a gull-wing, sharp angles and a spine air intake. Large wing and fuselage sections were made of low-temperature carbon-composite structures that, with a reduced number of connectors and seams and the angled design, significantly reduced the radar cross section (RCS) of the Bird of Prey.
This aircraft has a wingspan of 23ft, is 47ft long, weighs only 7,400lbs and is propelled by a Pratt and Whitney JT15D-5C turbofan. Boeing and USAF test pilots flew the Bird of Prey 38 times at the Groom Lake Test Range in Nevada in 1996 and 1997. Lessons from these design efforts have been incorporated in the recently flown Boeing X-45 UCAV and other advanced systems.
Composites already have had a major impact on military aircraft design and manufacture concepts and also have been used extensively in the latest generation of commercial aircraft. As this technology continues to expand its applications metal aircraft and missiles will be seen as a throwback to an earlier era. New techniques call for new skills and computer and materials science now lead the way in aerodynamics. Just as metal planes replaced wire and wood, designers are adjusting to the new realities and possibilities available with computers and composite materials.
mattwith regards too what? for cooking applications? light fixings? toilet roll holders? what are we talking about here ? i realised that being pedantic is a pre-requisit for this forum so i shall put that again.
What field are you talking off ? concrete with steel cabling can be classed at composite.
be more specific.
or is it a assignment you have been set?
mattThe CSS-1 perhaps. Based on the Russian SS-3, which itself is pretty much just a larger SCUD. The Japanese are adopting a two-fold solution, with SM-3 at sea for mid-course interception, and eventually Patriot PAC-3 on land for terminal stage/warhead interception (the ones that get through). Aren’t the Indians looking to acquire the ARROW system?
I dont know which one, reports have been mixed up and confused. some say Arrow, others say Arrow two while others talk about testing Arrow two and india buying Arrow in same article.
I am just going to wait till they actually get get either one.
mattyeah.. and the chinese CC-X or something series of missiles.. I am just wondering, because (sounds naive i know) if the Arrow 2 is capable then maybe it could be used by countries such as Japan, India ofcourse Israel, North Korea.. etc
mattWould it be correct to say that most of the IRBMS or missiles are based on some VARIANT of the scud?
mattHere you go Ja some food for your thought, i dont know much about subs but thought u migt be interested in this article.
http://www.strategypage.com/dls/articles/200471823.asp
The Five Nuclear Navies
by James Dunnigan
July 18, 2004
Discussion Board on this DLS topic
The nuclear attack submarine (SSN) is one of two vessels that signify a country is a major naval power (the other being the aircraft carrier). To date, five countries (the United States, the United Kingdom, France, Russia, and the People’s Republic of China) have these vessels in service, while at least one country (India) is looking into deploying them.
The United States has three classes of SSN. The mainstay of the American submarine force is the Los Angeles-class SSN. Sixty-two of these submarines were built, fifty of which remain in front-line service, making it probably the largest class of nuclear submarines that will ever be built. With four 21-inch (533-millimeter) torpedo tubes, it carries twenty-six weapons (either the Mk 48 ADCAP, the UGM-84 Harpoon anti-ship missile, or the BGM-109 Tomahawk). The last 31 Los Angeles-class SSNs add the Mk 45 vertical-launch system (VLS), which carries another twelve Tomahawks, making them closer to guided-missile submarines (SSGN).
The United States deploys two other classes. The Seawolf-class of nuclear attack submarines stopped at three from a planned class of twenty-nine. The Seawolf was designed as a super-submarine, designed to fight the Soviet Navy at its height. Carrying fifty weapons, and with eight 26-inch (660-millimeter) torpedo tubes, the Seawolf was designed for maximum performance. It delivered, posting a top speed of 35 knots – and remaining much quieter than the Los Angeles-class submarines. Reportedly, it is quieter at twenty-five knots than the Los Angeles-class submarines are at pierside. With the cutback of the Seawolf to three ships, the Navy has gone with the Virginia-class submarine. Less-capable than the Seawolf (it is much like the Los Angeles-class attack subs, but with a lot of the more-advanced systems from the Seawolf-class subs, particularly the quieting and sonar systems), it was supposed to be less expensive. The Virginia-class submarines are estimated to have a unit cost of $2.1 billion, but found a way to get the first six built for a total cost of $8.7 billion ($1.45 billion each). Like the Los Angeles-class, the Virginia-class submarines will be improved as the class is built.
The British SSN is the Trafalgar-class. This class of seven boats is considered on par with the Los Angeles class. Armed with five 21-inch torpedo tubes, the Trafalgar carries Spearfish torpedoes, along with the Harpoon and Tomahawk missiles. The Trafalgar-class subs (and the Astute-class, an evolved Trafalgar design) are much smaller in number, however, their edge lies in the training of their commanding officers. The British “Perisher” course is arguably the best training for a submarine commander in the world.
France’s SSN, the Amethyste class, is a small submarine (2400 tons, compared to the 6900 tons of a Los Angeles class). The crew is half that of the American Los Angeles-class as well (66 compared to 133). The submarine is slower than the American submarines (28 knots compared to the 35+ of the Los Angeles and Seawolf-classes). It carries L5 torpedoes and submarine-launched Exocet anti-ship missiles.
The Akula is the top-of-the line SSN in the Russian Navy. With eight torpedo tubes (four 650-millimeter and four 533-millimeter), it carries a variety of torpedoes. The Russian SSNs do not carry anti-ship missiles. However, the Type 65 torpedo has a range comparable to the Exocet (50 kilometers at 90 kilometers an hour/100 kilometers at 54 kilometers an hour), and is a wake-homing torpedo. The torpedo gives the Akula a one-shot kill capability against any naval vessel short of an aircraft carrier due to its huge warhead (1,984 pounds).
The Chinese SSN, the Han-class, is a much older (first unit built in 1974) and slower (25 knots) design. With six 533-millimeter torpedo tubes, it carries a decent punch, but primarily has older weapons (the SET-65E torpedo). Unlike Russian SSNs, the later units (403, 404, and 405) can carry the C-801 anti-ship missile.
Which of these navies has the best submarine? In a one-to-one matchup with another SSN, the British Trafalgar probably has the edge due to the high quality of its crews and sensors. British SSN commanders have much more tactical training than their American counterparts (mostly due to what some consider an overconcentration on engineering caused by the influence of Hyman G. Rickover). However, the United States Navy,
through sheer volume of numbers and solid training (albeit not as good as the British) probably has the best force overall. – Harold C. Hutchison (hchutch@ix.netcom.com)
Class Nation Displacement Number
Los Angeles USA 6,900 50 (12 retired)
Seawolf USA 9,000 3
Virginia USA 7,800 0+4
Trafalgar UK 4,700 7
Akula Russia 10,700 10+6
Amethyste France 2,670 6
Han China 4,500 5
“+” indicates the number under construction. Displacement is in tons.
mattAfter years of research, all they could do is add more weight and drag by adding another fin?
Interesting…
could also have decreased the weight as less structural reinforcement is likely to be needed.
mattDidn’t saythey were more advance, certainly dispelled the notion that it was less advance.
The rest is pure speculation about the efficacy of quadruplex, verses triplex redundancy… unless you would know this from your extensive work in FBW control systems, or mathematical modeling of control laws.. or… erm… I thought not! 😉
Certainly an attainable target in my opinion within the next decade. The pleathora of US X concept planes and stealth craft came up after the basic design tools were built and advanced upon. The LCA is doing just that, the composites design tools, the FBW, the phycical mathematical modeling, the datalinking, the avionincs / flight computers, the virtual prototyping are all concepts that are being mastered with the LCA. Once these blocks are in place, the rest should be relatively trivial.
Didn’t the Have Blue prototypes use the F-16 FBW hardware?
For the MCA type aircraft, with LO as a design feature, I would assume they would add to the building blocks and develop the necessary design tools/facilities for RCS reduction etc.
Nope can’t drop it – LCA is unique and far advance in this regard. Composites is key to weight savings, reduced RCS, increased airframe stiffness, improved product lifecycle with its resitant to corrosion – its extensively used in structrual members of the LCA. This is the same for the ALH, which was the first helo to use composites for load bearing memebers.
Thanks for stating the obvious – what that means in a glider vs a +9 -3.5 G multirole fighter is significant. That means you mastered technologies to make it work in that application. How many other fighters have a composite cobonded wing?
There was a very good writeup by a DRDO lab on some of the challenges that the use of composites caused. Things like mastering the metal composite interface joints, fatigue testing, fillers, bonding, fatigue/failure modeling, repair techniques… etc.
No the use of Composites inthe B-2, a stealth bomber (no points for guessing why it used composites) was a big advance as far as aircraft design…
Yes thats why India’s ADA composite design tools are being used by Boeing, and Airbus (in the A380), why their package AutoLay is now integrated with CATIA, and resold by Parametric in ProEngineer….
Won’t deny that the US and others are doing good work here as well, but the proof is in the pudding and India has certainly proven its own and advanced the art in the LCA.
Do you even know how many composite design tools are available on the market ?
mattWolverine – you might want to double check that. Last time I checked, and it might have changed, but the Gripen, Eurofighter, and the F-22 used a triple digital channel system.
The LCA was quadruplex digital FBW from the onset, this does not prove the system is superior or translates into more advance manuvering (as the analog Su-27 will attest to) – but it does prove the LCA is adavance from a technical level. That was the only point being made here…
The F-22 is in a different class of its own, the technical level is a goal India should strive for in the MCA and later…
About composites, I would say India is there if not ahead. The F-22 uses more advance metal alloys than composites as a % to the LCA. A better US example for composite use would have been the B-2.
Erm nooo, for one it doesnt prove it to be technologically anything its just the same technology used again, doesnt make it more advance then any of the other fights you mention, it just makes it more redundent. Also a Odd number when working with reduncy should be prefered over an even number as its easier to decide what channels are sending the computer the correct information.
For India to get to the F-22 level by the MCA would be a miracle concidering the comments made my DRDO it self. They want to keep it stupid simple.
As for composites please drop it, I am tired of Indians using that as a cure all pill, “hey we have 45% by weight composites” well that means nothing if most of that is semi structural bulk moulding compound. RMT is nothing new and 45% by weight means even less when most of that could be Glass fibre or even kevlar (kevlar is nothing new, infact its old).
Greater usage of composites doesnt mean thats its more advanced in terms of composites. in fact the percentage used means nothing! except that the airframe has used that much percantage of composites.
The B-2 probably doesnt go through the same type of cyclic or static loads as the F-22 is designed to and hence it can accomadate a larger amount of semi-structura to structural componants. who knows why it has more (except the designers). but it doesnt mean the composites used in the B-2 are instaneously technologically advanced.
Please just stop beating the composites drum. it means not a lot! Advance countries for composite research are (in no particular order)
1) Japan
2) USA
3) Germany
the EU as a block seems to be doing a lot on advanced composites.
matt****
btw you anti-composite Luddites had better get with the program. composites are the future of aerospace industry and they even look much better, more soothing :rolleyes:
Composites have been around for ages and the usage is still to capture a large part of the Traditional metal materials and even the exotic Alloys.
Remember, composites offer better SPECIFIC performance, this does not mean they would offer better performance in all situations.
We still have a lot to learn before they can replace all parts of a combat airframe.
mattYet on the other hand, the IAF is an airforce where dirty fuel and FOD still seem to be regular occuring problems. It is no problem if a crewchief at the squadron accidentally drops a hammer on the wing of a metal aircraft. Were he to do that on a composite wing, you’d need to get that wing checked at depot level. I’m personally not sure if the somewhat lower weight of composites is worthy sacrificing a lot of operational simplicity for. You can’t patch up composites, you can with aluminium.
Isotropic bulk materials are only popular for repair simply because we know lots about them and can predict with great comfort the behaviour of metals under strains and stresses, even with a simple phase diagram metalurgist could probabbly tell you the properties that metal would have.
This is where the Composite does not match up, we know enough and have enough confidence with metals to tell engineers that if they see a fatigue crack in a fusalage of a 747 they should drill a hole 9mm away to stop the crack front or atleast slow it down.
This might not be the case in composites.
Having said all that I would just like to point out that composites allows the operator to actually detect the damage in the wing and thus does give a certain safty factor. Yes the visual signs are fully dependent on the impact energy of FOD but again NDT techniques are around that can easily detect BVI damage. Even a simple field A Scan could help determin delams or debonding. The Giant thermal imaging robots that are employed by some companys are not always needed, its a case of matching the requirement and tool.
NPL actually have a lot of information on this already and more methods are being developed every year that can tell the user in real time of any damage on composites (using methods similar to Eddy current).
I’ll be ready to grow some confidence in the LCA as a fighter once it’s undergone full flight, systems and weapons testing, and has entered service trials with the IAF. And it’d better be with all the equipment the LCA fanboys say it will get – including the Kaveri (any breakthroughs i missed on that one btw?). Before that, i’ll remain as sceptical as i am.
The Chestbeating is putting off fans and well wishers of the LCA.
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