Kuo 1 Isaac Kuo WRIT 340 Dr. Elisa Warford December 2, 2013 The Incredible Versatility of the F-35 Lightning II By Isaac Kuo The F-35 Lightning II fighter is a fifth generation multi-role jet currently being developed by Lockheed Martin. Together with the F-22 Raptor, also designed by Lockheed, these two planes will become the primary fighter jets used in the United States military. The F-35 will match or outperform all of the current and previous generation fighters in combat, stealth, payloads, and speed, but the true genius of the F-35 is its versatility. The F-35 will have three variants, for the Army, Marines, and Navy, which will share 80% of the parts, dramatically driving down costs. In addition, the F-35B, the Marines variant, will have STOVL capabilities, the first supersonic aircraft with STOVL capabilities. These new developments make the F-35 the most advanced and incredible fighter America has built, and paves the way for even more exciting new developments. Introduction The United States military is currently in the middle of replacing and upgrading its fighter jet fleet. The two main planes at the forefront of this program are the F-22 Raptor, currently in service, and the F-35 Lightning II, currently in development and production. The F- 35 is a fifth-generation multi-role fighter jet, taking the state of the art technology from the F-22, and adding the versatility of the previous generations of fighter jets to create a new fleet of fighter jets that can be used in the major branches of military, all from the same design for the Kuo 2 plane. One of these variants of the plane, the F-35B, is designed for the United States Marine Corps and has revolutionary STOVL capabilities. STOVL stands for short take-off and vertical landing, and refers to planes that have the unique ability to take off vertically, or at least from significantly shorter than conventional aircraft, and land vertically as well. While some modern fighter jets have STOVL capabilities, the F-35B is the first fighter jet that can fly at supersonic speeds as well. The real advantages of the F-35 are in its versatility, including the STOVL F- 35B, giving the F-35 a large array of applications; the ability of the F-35 to take on virtually every mission makes it an extremely cost efficient and effective weapon for the military. History Before looking at what makes the F-35 Lightning different from other planes with STOVL, or even VTOL (vertical take-off and landing), capabilities, it is important to examine the developments in STOVL that makes the F-35 possible. The US military began exploring VTOL aircraft as early as 1951, when tailsitter aircraft were designed; tailsitter aircraft are, as the name suggests, aircraft that take-off and land on its tail, very similar to space shuttles. However, with the dozens of designs that were developed between 1950-1980, only two aircraft ever made it to production, with one of the planes being withdrawn after the fall of the Soviet Union. Also, in this timeframe, Boeing studied many ways to create a supersonic aircraft that also had STOVL or VTOL capabilities. Unfortunately, all of these designs never reached production. To date, the only supersonic aircraft with VTOL or STOVL capabilities is the X-35 (the experimental aircraft that led to the F-35), and eventually, the F-35[1]. Variants In order to bring down production costs without sacrificing functionality and versatility in the aircraft, Lockheed Martin developed three variants of the F-35, the F-35A, the F-35B, and Kuo 3 the F-35C; all three variants share eighty percent of their parts. The F-35 is the conventional take-off and landing variant[2], the F-35B is the short take-off and vertical landing variant[3], and the F-35C is the carrier based, or CATOBAR (catapult assisted take-off but arrested recovery) variant[4]. This allows the F-35 to meet the diverse needs of the different branches of the military with one design. All three variants and their key specifications are shown in Figure 1 below. The conventional F-35A, to be introduced in December 2016, is intended for use in the United States Air Force and will eventually replace the F-16. The F-35A variant is designed to meet or exceed all the capabilities of the F-16 fighter[5]. The F-35B STOVL variant is to be used by the United States Marine Corps, and is to be formally introduced on December 2015. The exhaust of the F- 35B includes a three-bearing swivel nozzle which turns and directs the nozzle towards the ground on take-off. The jet nozzle is oval-shaped instead of the typical circular shaped nozzle in order to limit the heat damage on the ground during take-off[6]. The F-35C variant is modified to suit storage and operation on an aircraft carrier. The F-35C carrier variant features larger wings and tails for take-off on the extremely short runway on aircraft carriers, folding wings to optimize storage, and stronger landing gear and tail hook for CATOBAR landing. The F-35C, to be formally introduced in February of 2019, is designed for use by the United States Navy, eventually replacing the F/A-18 Hornet fleet[4]. Kuo 4 Figure 1[7] Features Aside from the wing and payload changes between the variants of the F-35, the main features of the F-35 remain the same and represent the latest advancements in aerospace and weapons engineering. The F-35 is a smaller, single-engine sibling of the F-22 Raptor, and it includes many of the same technological advancements. The USAF plans to use the F-35 as the primary fighter jet for combat missions because of its advanced radar, target recognition, and data processing power[8]. Lockheed Martin claims the air-to-air combat abilities of the F-35 are second only to the F-22 Raptor; however, the F-35 is superior to the F-22 in “basing flexibility and advanced sensors and information fusion[9].” Kuo 5 Specifically, the F-35 has durable, low-maintenance stealth technology, using a more cost efficient structural fiber rather than the high-maintenance coating on the F-22 Raptor. The F-35 is powered by the Pratt & Whitney F135 engine, which brings the plane to a maximum speed of over Mach 1.6[2]. The F135 engine can produce a maximum thrust of over 50,000 lbf (220kN), the most powerful engine in a fighter jet as of 2010[10]. The F-35 has two internal weapons bays, and additional external missile storage for up to four underwing missiles and two more near the wingtip pylons. These weapon bays allow for a diverse array of weapons that make the F-35 extremely versatile because it can carry many different weapons that allow the F-35 to be very effective in both air-to-air and air-to-ground combat. Very similar to the F-22 Raptor, the F-35 also has extremely effective stealth technology. The F-35 has a low radar cross-section due to its shape and its stealthy materials, including the fiber mat[11]; in addition, the F-35 was designed to have a low radar profile, something current and previous generations of fighter jets lack. The F- 35 flies most missions without the large external fuel tanks to minimize its profile and add to its stealth. STOVL on the F-35 However, what truly sets the F-35 apart is its STOVL capabilities. While the F-22 has a smaller radar cross-section than the F-35, the F-35 is much more versatile in its applications because of its STOVL capabilities. The F-35B gets its STOVL capabilities from the Rolls-Royce LiftSystem. The main components of the LiftSystem are the lift fan and the Three Bearing Swivel Module, also known as a 3BSM[12]. The 3BSM is swiveling nozzle that deflects the main engine exhaust towards the ground in order to take-off vertically. In addition, the Lift System consists of a lift fan near the front of the fighter and provides a counterbalance thrust with two counter-rotating blisks, or fans[13]. The engineering marvel that is the LiftSystem, combined with Kuo 6 the other breakthrough technologies on the F-35, puts the F-35 far ahead of all current and previous fighter jets. The operation and functions of the LiftSystem are shown in Figure 2 below. Figure 2[14] Nevertheless, despite the technological breakthroughs present in the F-35, there is still room for improvement for future designs, particularly in the STOVL technology. Fighter jets with STOVL capabilities are most useful on aircraft carriers, where the runways are very short, and even fighter jets designed specifically for these conditions, such as the F-35C, need catapults and hooks in order to take-off and land properly. Because of the extremely take-off field length limitation on aircraft carriers, it would be ideal to use fighter jets with STOVL capabilities, eliminating the need for catapults and hooks. However, this is not yet possible, because the heat generated from the exhaust would seriously damage the hull on aircraft carriers. Even the Marine Corps, the primary users of the F-35B, can only utilize the STOVL on specifically designed concrete built to withstand the intense heat; the F-35B cannot use its short take-off system on a regular runway.