MULUBJA
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About LSA.
LSA will be known as a marvel of Indian frugal engineering skills like Mangalyaan mission. No one will ever accept that a supersonic stealth fighter can be made with a budget of just USD 300m which is less than the development budget of world’s cheapest car called Tata Nano. It is a completely re-designed HF-24 aircraft with single engine. HF-24 all metallic airframe weighed 2.85tons with a length of 15.87m giving it an OWE of 6.25 tons with four 30MM Aden Cannons. LSA design is 13.75m long with one GSH-30mm gun and mid wing Delta-Tail planform with lots of composite construction and avionics far lighter compared to HF-24. I have calculated an empty weight of 5.75 tons for LSA including Internal bay launchers, bay door opening systems. The OWE of this aircraft is expected to be 6 tons. The weapon load is 5.75 tons with internal fuel volume of 3.5 tons giving it MTOW of 15.25 tons. The 3D TVC of this aircraft will be based on the principles of Sea Harrier as this aircraft will have stable design. A switch on HOTAS will engage TVC and merge the movement of elevators and rudders to TVC giving the pilot ability to use TVC on demand during combat and switch between stable to unstable flight regimes on demand. 3D thrust vectoring nozzles will also act as additional control surface and its twin rudders as V-tail will augment the control authority of Tail plane based on a combination of speed + Alpha + Pilot demand. This design uses off-the-shelf technologies presently available within India developed for LCA program and does not need any R & D for any of its systems. The FOC will be achieved for those weapon systems which are operational on Mig-21 and LCA MK1. Any additional weapons integration will be done post FOC. The internal bays will be certified for full weapon configuration for SEAD/DEAD ops as part of FOC. LSA will have a seamless entry into service as it will use the infrastructure and support equipment created for Mig-21 for operating from any air base of IAF. LSA will have a total of 16 stations for carrying a variety of loads comprising six internal, six under wing, two wingtip and two CFT stations. LSA uses air foil of HF-24 which was the first ever supersonic, supercritical air foil of the world. The HF-24 airfoil round LE will be converted to sharp LE for better subsonic /supersonic performance with addition of LE maneuver Flaps and double slotted TE Flaps. Even the fuselage has been shaped as per this airfoil. The modified pure Delta planform with LERX has the Reynolds number of Mig-21 wing. I have enumerated below the changes I had made to the HF-24 design to make it LSA and attached the superimposed images of LSA & HF-24 to highlight them.
LSA will be known as a marvel of Indian frugal engineering skills like Mangalyaan mission. No one will ever accept that a supersonic stealth fighter can be made with a budget of just USD 300m which is less than the development budget of world’s cheapest car called Tata Nano. It is a completely re-designed HF-24 aircraft with single engine. HF-24 all metallic airframe weighed 2.85tons with a length of 15.87m giving it an OWE of 6.25 tons with four 30MM Aden Cannons. LSA design is 13.75m long with one GSH-30mm gun and mid wing Delta-Tail planform with lots of composite construction and avionics far lighter compared to HF-24. I have calculated an empty weight of 5.75 tons for LSA including Internal bay launchers, bay door opening systems. The OWE of this aircraft is expected to be 6 tons. The weapon load is 5.75 tons with internal fuel volume of 3.5 tons giving it MTOW of 15.25 tons. The 3D TVC of this aircraft will be based on the principles of Sea Harrier as this aircraft will have stable design. A switch on HOTAS will engage TVC and merge the movement of elevators and rudders to TVC giving the pilot ability to use TVC on demand during combat and switch between stable to unstable flight regimes on demand. 3D thrust vectoring nozzles will also act as additional control surface and its twin rudders as V-tail will augment the control authority of Tail plane based on a combination of speed + Alpha + Pilot demand. This design uses off-the-shelf technologies presently available within India developed for LCA program and does not need any R & D for any of its systems. The FOC will be achieved for those weapon systems which are operational on Mig-21 and LCA MK1. Any additional weapons integration will be done post FOC. The internal bays will be certified for full weapon configuration for SEAD/DEAD ops as part of FOC. LSA will have a seamless entry into service as it will use the infrastructure and support equipment created for Mig-21 for operating from any air base of IAF. LSA will have a total of 16 stations for carrying a variety of loads comprising six internal, six under wing, two wingtip and two CFT stations. LSA uses air foil of HF-24 which was the first ever supersonic, supercritical air foil of the world. The HF-24 airfoil round LE will be converted to sharp LE for better subsonic /supersonic performance with addition of LE maneuver Flaps and double slotted TE Flaps. Even the fuselage has been shaped as per this airfoil. The modified pure Delta planform with LERX has the Reynolds number of Mig-21 wing. I have enumerated below the changes I had made to the HF-24 design to make it LSA and attached the superimposed images of LSA & HF-24 to highlight them.
- The nose has been shaped to become a lifting surface and also provide very predictable vortex shedding with a very small boundary layer to help reduce the size of air intakes as the gap between the boundary layer diverter and the intake will be 8 cms only which is lesser than any other design with similar intakearrangements.
- The fore body shape coupled with LERX will also provide a wing-body AC which will be of special use during super cruise. The LERX will provide a very strong vortex to pull the airflow towards the fuselage by increasing the span efficiency & overall lift. They will also increase resistance to spin and provide very effective high AOA stability.
- LSA nose is shaped as a hexagonal and has a maximum width of 1.4m compared to 1.2m width of HF-24. The width at intakes is 2.25m. Length of the nose has been reduced and will have same drag polar as that of HF-24.
- The nose provides space for IRST, OLS-K EOTS and 0.45 sqm area for AESA radar. The gun will be accessed from main weapons bay for loading and unloading including servicing.
- The cockpit is very spacious and offers same comfort level and equipment fit as that of Jaguar aircraft and provides 360* visibility.
- HF-24 had 4x30mm guns with 130 rounds each internally. This space has been converted to avionics bay which will be lowered down like the HF-24 rocket pack for maintenance purposes and to access various LRUs. This will also ensure that we can upgrade LSA avionics anytime without the need for changing the internal set up. The 50x68mm Rocket pack will now house the 150 rds of ammo for one GSh-30mm cannon to be fitted in the nose.
- LSA is a mid-wing design compared to low-wing HF-24. Raising the wing on the fuselage and lowering the engine to have a thrust line below the wing line will provide a nose pitch up moment due to thrust which will assist the Tail plane in providing very high control authority and outstanding pitch rate ability far superior to any RSS design presently flying in India. This combination will also help reduce Trim Drag.
- The circular intakes have been converted to wing root like intakes and allow for airflow of 84kgs/second with 8cms left for boundary layer bleed off on each side.
- LSA wing has a sweepback of 57* and area of 31.7sqm with 8.5m span and 2.95m long LERX & Aspect ratio of 2.28 which is best figure for an interceptor aircraft. HF-24 quarter chord sweepback was 45* while LSA is 49*. The wings will have LE slats & TE double slotted 67% exposed span flaps borrowed from Jaguar. The Ailerons design is borrowed from Mig-21. Primary FCS will be controlled by EHSAs and will have Power-by-Wire architecture which is same as FBW in Direct Law. The secondary flight controls & weapons bay doors will be actuated by Hydraulics & rotary electrical actuators.
- LSA provides for 50% additional internal fuel volume compared to HF-24.The additional fuel capacity is a result of single elliptical air duct and 10cm thicker fuselage compared to HF-24 which had 1.45m thick fuselage.
- LSA will have Gripen like fully internally housed telescopic IFR probe to maintain low RCS.
- The main weapons bay is 4.3m long, 62.5cms deep and 1.1m wide. HF-24 had a 35cms deep fuel tank below the fuselage which has been converted into main weapons bay by increasing the fuselage thickness by 10cms and reshaping the air duct to elliptical shape like that of F-16. The main bay is capable of carrying 2xK77M or 2xAstra or 2xHarpoons or 2xKH35UE or 2x1000lb bombs or 8xSPICE250 and every weapon designed for Pak-Fa.
- Large internal weapons bay of LSA can be adopted to carry multiple payloads for specialist missions like F-18SH Growler for exclusive EW/Recce role and can be converted to carry directed energy weapons of the 6th Gen fighters in future.
- Each side bay can carry one 1xK-77M/Astra and 1xK-74M2/ASRAAM. The Lower side bays are 3.9m long while the upper side bay is 3.25m long and their combined width is 70cms and depth is 55cms.
- The outstanding wing-body blending will add a large part of overall lift besides drastically reducing the Interference drag. LSA has the best wing-body blending compared to any other aircraft of similar nature anywhere in the world and it is nearly as good as a flying wing in mid fuselage section.
- The rear part of the fuselage has been tapered inwards at an angle of 7.5* to give it a Boat tail shape to reduce drag at all stages of flight. Tail plane has sweepback of 57* with span-5.25m, tail arm-4.3m, Vbar-0.34.
- The use of twin rudders positioned out of LERX wake, will provide much superior directional control with extremely high yaw stability besides acting as a V-tail to provide increased nose pitch up authority at extremely low speeds and extremely high AOA. This helps to raise the combined Vbar to 0.44 for tail plane and V-tail. The twin V-tail shaped rudders will also lower the overall stance of the aircraft which will reduce its visual & radar cross section to increase its stealth capability.
- The wheel base is 5m, wheel track-2.6m, Topple angle-30*, Nose wheel weight-15%, main wheel weight-85%. The nose gear is same as Mig-21 and the main gear is borrowed from LCA. The main gear doors will also be the airbrakes.
- The tail clearance angle is 20* which allows this aircraft to fly 15 Alpha approach to exploit the full potential of LERX. LSA will have approach speeds of less than 115 kits and can be easily adopted for Carrier operation.
- The engine of choice is EJ230 with 72KN dry thrust and 108KN wet thrust giving it a TWR of 0.79 at loaded weight on dry thrust and a TWR of 1.32 in Combat weight configuration on wet thrust. LSA will have a sea level stall speed of 88 kits at 1.6Cl in combat flap settings & load giving it Cat-1 ITR & STR at sea level conditions of 37*/sec & 30*/sec for 9G & 6G loads respectively with 700 feet radius of turn. These figures are same as that of F-22.
- The equipment fit will have Central Mission Computers which will integrate all weapons, sensors, communication equipment, navigation equipment and on board systems to provide a composite fused picture to pilot on touch screen based glass Cockpit with cockpit speech recognition and voice command system. LSA will have ELTA designed GaN based AESA. A chin mounted EOTS system based on OLS-K pod components configured for internal fitment providing limited capabilities like F-35.
- LSA will have a fault detection, display & diagnosis system like A-320 to shorten turnaround inspection time. I have spoken to Israeli Aircraft Industry and they are willing to provide full support to create tailor made solutions for LSA.
- Mig wing LSA is the least risk design and can be created in two years.
- Shown below is the RCS diagram of LSA created using ANSYS software at 500MHz frequency with all metallic skin. The frontal RCS is -36dbsm and side RCS is -22dbsm which is same as that of F-22 and superior to the RCS of F-35. The X-band RCS with composite skin & RAM coating is likely to be even better than what has been calculated. The internal weapon load and overall Stealth of LSA is superior to even under development AMCA.
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