The release of global RFIs on January 19, 2019 by India’s state-owned Hindustan Aeronautics Ltd (HAL) for the supply of three separate aircraft fuselage assembly jigs (one unit of each type) meant for fabricating the front, centre and rear fuselage sections of a single full-scale engineering-test model of the projected LCA-AF Mk.2 multi-role combat aircraft (MRCA) is indicative of what the DRDO’s Bengaluru-based Aeronautical Development Agency (ADA) had proposed back in 2014, and which can be viewed here:
https://pdfs.semanticscholar.org/fd95/a760d06858325ba702bd98d15dfffbede300.pdf
It can thus be safely inferred that ADA has passed on the Design Applicability List (DAL) and Standard of Preparation (SOP) documentation to HAL for the full-scale engineering-test model of the projected LCA-AF Mk.2, which in turn will be used for optimising the design and location of the various mission avionics sub-systems/LRUs and related wiring harnesses, hydraulic pipings, accessories, and skin-level distributed apertures for sensors of the integrated EW suite, inclusive of radar warning receivers-cum-jamming emitters, laser warning receivers, and missile approach warning systems.
Simply put, jig-less assembly aims at reducing or eliminating the need for product-specific jigs during airframe assembly by developing new assembly concepts, models, tools and procedures. In the new concept of jig-less aircraft assembly, the end locators are replaced by transferring the holes directly on to the part. These holes are made by high-precision machines. In this approach, all the parts will have at least two holes so that one part can be assembled with the adjacent part. These holes are termed as ‘key holes’. In this method, the tooling elements (end locators) are eliminated and only the jig is used as the main assembly structure. This approach reduces the tool manufacturing time, reduces the product-dependent fixture and also increases the accuracy of the assembled product. It also results in a reduction of the number of tools and joints (rivets), and subsequently weight as well. And going hand-in-hand with jig-less assembly is the practice of using modular tooling solutions.
The most common tooling technology for aircraft assembly used today is conventional tooling consisting of steel beams that are welded together. Such toolings are tailored for a specific tooling operation. Since conventional tooling is designed to a specific application, each assembly has its own dedicated tooling, or product-specific tooling. In addition, when building a complex product like a MRCA, the final design is forced by changes that immediately affect the tooling design. This necessitates modifying the tooling/ locating holes or shimmed pick-ups to new locations. Hence, the preferred solution today is modular tooling, which is built for a dedicated purpose as well, but the surrounding system and distance supports are designed from a toolbox of modular components. The framework of modular tooling is screwed together. It thus helps in reducing the cycle-time of assembly, thereby enhancing the production rate. Modular tooling also helps to design jigs/ fixtures that will meet a group of components.
Front fuselage section
The front fuselage assembly jig for the LCA-AF Mk.2 will be made up of various modules like the composite radome, floor assembly, canopy, windscreen, starboard and portside air-intakes, twin canards, starboard and portside wing leading-edge root extensions. The assembly will comprise approximately 1,300 individual parts, out of which 40% are estimated to besheet metal, 30% being machined parts and the remaining 30% being made of carbon-fibre composites (CFC). The length of the assembly is 6,100mm, with a maximum width of about 1,100mm. The assembly will comprise 23 stations, and the entire assembly will weigh some 500kg.
The component assembly will comprise the following attachment points: 1) Bulkheads for cockpit avionics 2) Nose landing gear pivot 3) Nose landing gear jack-point 4) Nose landing gear up-lock 5) Windscreen 6) Canopy 7) Wing leading-edge root extensions 8) Air intakes 9) Radome 10) Starboard side fixed air-to-air refuelling probe 11) Longerons 12) RLG-INS and GPS receiver mounting structure 13) Cockpit floor 14) Shear walls 15) Inclined bulkhead 16) Doors/hatches 17) Canards 18) Mooring points 19) Hauling points 20) Ejection seat brackets 21) Symmetry check-points 22) System installation brackets 23) Air data probes: Nose air data probe (NADP)/side air data probe (SADP)/Angle-of-attack/Angle-of- Side-slip (AOSS) locating points 24) Equipment bay housing the environmental control system (ECS), digital flight-control computer (DFCC), mission avionics, and an on-board oxygen generation system (OBOGS).
Center fuselage section
The centre fuselage assembly jig will be made up of modules such as: air-ducts and side-skins, spine, main landing gear bay, shear wall, fuel tanks, and a dividing wall structure. The assembly will comprise approximately 1,600 parts, out of which 40% will be sheet metal, 30% will be machined parts and remaining 30% are to be made of CFCs. The length of the centre fuselage is about 4,500mm with a maximum width of some 2,100mm. The centre fuselage assembly will comprise 15 stations and the it will weigh about 900Kg. Since the centre fuselage section needs to be coupled with the front and rear fuselage sections, the inter -changeability (ICY) media are critical.
The centre fuselage assembly will comprise the following: i) Bulkheads 2) Trouser duct 3) Circular duct 4) Side-skin structure 5)Top-skin structure 6) Fuel Bay side-walls 7) Longerons 8) Shear walls 9) Doors and hatches 10) Fuel tanks 11) Main undercarriage 12) Spine structure 13) Wing pick-up points 14) Landing gear doors 15) Gun-bay structure (meaning the Gryazev-Shipunov GSh-23 cannon has been repositioned to the starboard side of the upper centre fuselage) 16) Lifting points 17) Other systems installation inter-changeability requirements 18) Symmetry points.
Rear fuselage section
The Rear fuselage assembly jig will be made up of modules like the engine bay doors, spine and fin attachment, and brake parachute. This assembly will comprise approximately 900 parts, out of which 30% will be sheet metal, 40% will be machined parts and remaining 30% will be made of CFCs. The length of this section will be about 3,300mm with a maximum width of about 1,800mm. The rear fuselage assembly will comprise eight stations and the total shell-weight will be some 400Kg. The rear Fuselage needs to be coupled with the centre fuselage and hence the ICY media are critical.
The assembly will include the following: 1) Bulkheads 2) Shear walls 3) Floors 4) Engine mounts 5) Doors 6) Wing attachment points 7) Covers/Hatches 8) Fin attachment points 9) Spine structure 10) Hauling attachment 11) Tie beam 12) Shroud 13) Trailing-edge extension 14) Elevon inboard actuator attachment 15) Symmetry points.
Larsen & Toubro-furnished equipment on the Tejas
OEMs expected to respond to the RFIs will likely include Airbus Military Aircraft, BAE Systems, Leonardo Group’s Alenia Aeronautica subsidiary, Boeing, Dassault Aviation, Lockheed Martin, SaabTech and Russian Aircraft Corp.
Subject to a contract award taking place by the year’s end, the three different assembly jigs will begin arriving at HAL by 2022, following which another three years will be required for optimising the design and location of the various mission avionics sub-systems/LRUs and related wiring harnesses, hydraulic pipings, accessories, and skin-level distributed apertures for EW sensors. Consequently, only by late 2026 will be it possible to roll out the first flying prototype of the LCA-AF Mk.2. Add to this 2,000 hours of flight-tests with four flying prototypes over a period of three years. So, for all intents and puposes, the LCA-AF Mk.2 will not enter series-production until 2030.
TRISHUL: LCA-AF Mk.2's Fuselage Design Details Emerge, Plus BVRAAMs, LRAAMs & ASMs Powered By SFDR
@randomradio @vstol Jockey @Falcon
Like I said, we're being extremely optimistic with regard to Mk-2 timelines. And
@randomradio was expecting us to start building Mk2 prototypes this year itself.