Wings Tandem Test: Fill & Download for Free

Firstly understand the chronology of Tejas induction. SP stands for “Series Production” here.16 Tejas Mk1 single seat aircraft in the IOC (Initial Operational Clearance) configuration were delivered to 45 Squadron “Flying Daggers”.4 Tejas Mk1 twin seat conversion trainers in IOC configuration (which are yet to be manufactured) along with the 16 delivered are numbered SP01 to SP20, all in IOC configuration.The first FOC (Final Operational Clearance) configuration fighter is SP21 which flew last week. It is a single seat aircraft which will be a part of 18 Squadron “Flying Bullets” in Sulur next year.The next 15 (total 16) aircraft will be single seat & the next 4 will be twin seater conversion trainer aircraft.This makes the first order of 40 Tejas Mk1 aircraftThe follow on order is of 83 Tejas Mk1A aircraft.Now lets see how is the FOC configured Tejas SP21 different from the IOC counterpart.The first difference is visual. The SP21 (& follow on aircraft) have a fixed in-flight refueling probe.The fixed refueling probe is like the one in Mirage 2000 Mk5 which extends the range & endurance of the aircraft upto 8 hours without additional touch downs or pit-stops to refuel.External fuel tank:The Tejas IOC has provisions of only underwing fuel tank of 800 and 1200 liters. The FOC variant (SP21) will have provision of an additional 725 litres centre line drop tankPressure refuelling capability of upto 50psi which can refuel the aircraft within 8 minutes for internal tanks only and 12 minutes incase of both internal and external tankBoth these modifications will increase the range & endurance of the fighter as Tejas is touted to be a short ranged fighter.Inclusion of internal cannon:Though the cannon trials held in 2015 itself it was not a part of the IOC batch production. In FOC aircraft starting with SP21, the cannon will be present.Tandem pylon in the inboard wing hardpoints.Now the inboard pylons can hold two munitions in tandem. This would improve the weapon carrying capability without increasing the air drag. Though Multiple ejectors would be incorporated in the Mk1A version only.Beyond Visual Range (BVR) missiles:Israeli I-Derby-ER missile was tested and cleared for the entire FOC envelope via exhaustive study of missile separation characteristics. These missiles can be launched at targets beyond visual range & can hit targets upto 100 km.Improved wing navigation lamp.In-flight wind mill relight.Increased AoA to 28 degree from 24 degree in IOC.Apart from the improvements in the aircraft, HAL has also matured in the manufacturing process. HAL has incorporated many key improvements in the production line to reduce the cycle time. These includeUse of robotic drilling,Reduction in PI (pre-installation checks) of LRUs (line replace units),Maximizing the outsourcing for detail components,Outsourcing of complete major assemblies like wing and fuselage,Maintainability improvement through enhanced looming cut-outs and ICY (inter-changeability) of pipes and panelsUse of copper mesh on wing assembly.Some images from production line of SP1:All the IOC standard aircraft of the 45 Squadron will be upgraded to FOC standard after the first batch of 40 aircraft will be delivered.Hope this helps.Footnotes:HAL readies new variant of Tejas ahead of maiden flightHAL on a war-footing to roll out 4 new Tejas variants in 3 monthsHAL Tejas - WikipediaFirst Tejas FOC fighter takes to the skies with loads of upgraded featuresSubhadeep Paul

As other answers have indicated, the B-47 was an historic landmark in aircraft design; moreover it was based on another historic landmark design - the B-29. As in the wording of the question, “what were the fatal design flaws of the B-17″ answered previously, the use of the word “faulty” in this question is seriously misguided. Just as the B-17 did not have “fatal design flaws,” the B-47 most definitely was not a “faulty” aircraft.Work on the B-47 began in late 1943 when the B-29 was just beginning to enter service tests and B-17s were heavily engaged in daylight bombing raids over Germany. The initial layout was similar to that of the B-29 but with four jet engines and in fact the B-47 can be thought of as a jet-powered B-29 in terms of general design, size, and equipment details. As research into advanced aerodynamics evolved, boosted by data on swept wings obtained after the collapse of Nazi Germany, the B-47 design was revised to incorporate swept wing and tail surfaces. In addition, power requirements were such that it took six rather than four of the early jet engines to provide adequate performance. After investigating several alternative layouts for these engines, Boeing creatively arrived at the solution: engines slung underwing in pods much like ordnance or drop tanks had been used during the war. This solution offered the cleanest profile drag but did require relocation of the wing to shoulder position.Detailed design and prototype work proceeded very rapidly by comparison with today’s aircraft and the XB-47 made its first flight on 17 December 1947 - 44th anniversary of the Wright Brother’s flight at Kittyhawk - creating a startlingly vivid illustration of the very rapid evolution of aircraft design over that period. The new aircraft demonstrated outstanding performance and excellent handling qualities. In addition, Boeing had refined systems such that only three crew were required. The leap from a 350 mph B-29 with 10–11 crew to a 600 mph aircraft with three crew comprised one of the most amazing step function changes in military aircraft history. The XB-47 was in a class by itself and set the standard for all large jet-powered aircraft since.The price paid for these pioneering efforts was limited internal fuel capacity and use of bicycle main gear, which took fuselage package space and limited braking to two axles. Because the aircraft drag profile was so slick, stopping it on standard USAF runways was a concern, leading to the use of a braking parachute. To help the early low-performance turbines during takeoff, RATO (often inaccurately termed JATO) was built in to the rear fuselage as standard equipment. Pilots sat in tandem under a fighter aircraft-style canopy with the bombardier-navigator seated ahead of them in the lower fuselage. All had ejection seats.Demand for the B-47 was such that the original wartime B-17 production pool among Boeing, Douglas, and Vega was reactivated. Progressing through several variants, the B-47 became the backbone of SAC until the larger B-52 entered squadron service in volume. Facilitating this deployment were airborne tankers - also supplied by Boeing - using KC-97 aircraft, which were derivatives of the B-29. The performance incompatibility between these two aircraft motivated Boeing and the USAF to seek higher performance versions of the tanker. Over time, in concept, Boeing combined the KC-97 with the B-47 by using wings, tail, and engines of the latter married to a fuselage of the former, but with the wing in the lower position.The resultant aircraft - the model 367–80 - became the basis for both the KC-135 jet tanker and the highly-successful range of Boeing jetliners begun with the 707. Thus the B-47 design had very far-reaching effects, and in fact forms the general design formula for all large jet aircraft today using swept wing and tail surfaces combined with underslung engines mounted in pods. However, as the B-47 aged its mission profile - originally set as a high-altitude level bomber - was changed to the tactical requirement of low-level toss bombing. This fighter-like maneuver created airframe stresses that required special wing-mount reinforcements that enabled the aircraft to continue service in this role. If there was a “fault” in the aircraft, it was that it required special structural redesign for a mission never contemplated in the first place.The B-47 is the poster child of the Golden Age of the USAF. This was vividly illustrated when General K.B. Wolfe, chief of Air Materiel Command, flew in his personal VB-17G executive transport to meet with Boeing executives and ultimately fly in the XB-47. He went from a 225 mph unpressurized aircraft to a 600 mph pressurized aircraft in essentially one step, and immediately became an ardent supporter of the B-47 program. As for Boeing, their immortal B-17, landmark B-29 together with its B-50 and KC-97 derivatives, and both the B-47 and B-52 - along with the KC-135 - all served together at the same time during the mid- to late 1950s. In that era these Boeing aircraft comprised the backbone of the USAF, and the B-47 was the most important vertebra. Now somewhat out of mind and sight, the shadow of the B-47 still falls on much of aviation. It set the plateau upon which most of commercial and military aviation still operate and at the time of its debut was clearly perceived as the greatest representation of a boundless postwar aerial future.AddendumA reader has suggested the following in terms of edits: “I think it’s worth mentioning the B-36, which was between the B-29 and B-47. Do you know what the links were between the 36 and 47? The 29 and 47 were Boeing programs.“ In response:The article is about the B-47 including its design origins and impact on aviation history. It was not intended to be a comprehensive history of USAF bomber programs. However, as succinctly as possible, below is an answer to the question posed above.The B-36 was an important gap-filler during the transition from piston-powered bomber aircraft to jet-powered bomber aircraft. Conceptually it can be thought of as a B-29 expanded to maximum size and given auxiliary jet power. It was not on the line of design and technical evolution from B-29 to B-47 and can be seen - in aerospace engineering terms - as an evolutionary dead-end.USAAF/USAF bomber-series aircraft designated -37 to -46 were of three types: conventional piston-engine designs that received official specifications serially in terms of time (i.e., B-37/Lockheed Ventura; B-38/Allison-powered B-17); new experimental aircraft using piston engines (Douglas XB-42); or new jet-powered aircraft (Douglas XB-43, North American B-45, Convair XB-46). The latter jet-powered aircraft were straight-wing developments that did not compare to the B-47 in terms of flight performance; only the B-45 went into production, and while it gave good service it was not competitive with the B-47.

I will not talk about procurement cost because it’s a very complicated business and an outsider can’t know the details. But IAF requires Tejas.IAF’s philosophy is to maintain a spectrum of fighters:1) Heavyweight (Mainly for air superiority with secondary multi-role capability)2) Medium weight (Multi-role, ground attack, strike, deep penetration)3) Light weight (Interception with limited multi-role capability)Heavyweight:Su-30MKI (air-superiority+multi-role)Medium weight:MiG-29 (air superiority+multi-role)MiG-27 (Ground attack)Mirage-2000 (Multi-role)Jaguar (Ground attack, deep penetration)Light weight:MiG-21 (Interceptor)Tejas is a modern jet developed to replace MiG-21. It doesn’t have to be similar to Su-30MKI because it’s category and role are supposed to be different.Is Tejas bad?Well, It's1) 4+ gen (Mk1A will be 4.5 gen including AESA radar, better EW suite, self-protection jammer etc.),2) all weather/all terrain/all altitude compatible (being tested in every condition for 17 years),3) swing-role (computerized configurable multi-role capability),4) Advanced flight control system (Quadruplex 3-axis digital fly-by-wire)5) advanced avionics and systems (Glass cockpit, HUD, HMD/S, HOTAS, Night vision goggle, Multi-mode radar, EW suite with radar warning receiver, LASER warning receiver, Missile approach warning receiver etc., targeting pod, LASER rangefinder etc.)6) agile and highly maneuverable (cropped compound delta-wing design, unstable design with relaxed static stability),7) semi-stealthy (90% surface area composite material, small airframe, blended wing, Y-inlet, RAM coated body, Indium Tin oxide coated canopy, EW suite),8) production friendly (single piece monolithic honeycomb structure tailfin, composite structure reducing 40% parts, 50% fasteners, 2000 holes, cost and time compared to metallic design)9) maintenance friendly (can do 6 sorties per day without problem)10) versatile (Indian, Russian, Israeli, western weapons compatible, 8 hard points- standard for a small light fighter, tandem pylon),11) safe (zero accident in 4000+ test flights along with 3 years of operational flights, Digital fly-by-wire, advanced control law, auto-pilot, auto-level, Integrated avionics, computerized health monitoring system, FADEC engine etc.),12) long endurance (3000 km range with one aerial refueling- hence good range, On-board oxygen generator system, pilot-friendly systems etc.),13) cheap (just 1 billion USD overall developmental cost- lowest in all light fighter programs in the world)14) Diverse (Air Force version fighter, Air Force trainer, Lead-in fighter-trainer, Naval fighter, Naval trainer, Unmanned version) and high scope of upgrade (mk1, mk1A, mk2)15) indigenous (designed, developed and manufactured in India, 75.5% indigenous LRUs in 2016 which was increasing).It’s definitely nice.We need it because it’s good and it’s highly important to be self-dependent in aviation sector in defense. Tejas program has given India a fighter (operational), a naval fighter (reached maturity for carrier testing), a jet engine program (reached maturity for aircraft testing), a fighter-graded AESA radar program (prototype ready) as well as a whole aerospace ecosystem as a network of 50+ labs, 20+ educational institutes and 500+ firms. All these are not for throwing out to dustbin.