Forum: F-35 Design & Construction

JSF: Integrated Avionics Par Excellence

The F-35 Joint Strike Fighter, a multirole, multiservice aircraft, marks a watershed in avionics integration and processing centralization, and introduces a new way of fighting.

By Charlotte Adams

What must a 21st-century tactical aircraft incorporate to satisfy the needs of the U.S. Air Force, Navy and Marine Corps and international customers seeking a multimission air vehicle? The short answer is plenty of onboard and offboard data collection, processing and fusion. The long answer emerges from a close look at the Joint Strike Fighter's (JSF's) design.

The stealthy, supersonic fighter, designated the F-35, is expected to replace U.S. F-16s, A-10s, F/A-18/A/B/C/Ds, F-14s, and AV-8Bs, as well as UK GR7s and Sea Harriers. The U.S. Air Force wants to buy 1,763 Joint Strike Fighters; the U.S. Navy and Marines, 680; the Royal Air Force, 90; and the Royal Navy, 60. First flight of the conventional takeoff/landing (CTOL) version is expected in 2005. CTOL, short takeoff/vertical landing (STOVL), and carrier-capable versions will feature "high 90 percent" avionics commonality.

The affordability, size and mission goals for an aircraft developed with funding from eight countries, as well as the United States, have dictated unprecedented sensor overlap and processing centralization. The electronically scanned radar array, under the control of mission systems software, will be able to perform electronic warfare (EW) functions, and the EW system will share some com/nav/identification (CNI) apertures. The JSF's infrared (IR) sensors will use detector/cooling assemblies of a common design. Integration also means the use of common modules wherever possible, both in the integrated core processor (ICP) and in other key systems, as well as the use of a 2-gigabit/sec Fibre Channel backbone for instant communications between the ICP and the sensors, CNI system and displays.

Designers intend integration and cooperation to drive breakthrough situational awareness. Data from radar, electro-optical, EW and CNI sensors?not to mention offboard systems?will be fused by mission systems software and presented to the pilot as an intuitive tactical picture on a panel-wide head-down display. A helmet-mounted display system (HMDS) will project the IR picture and urgent tactical, flight and safety symbology onto the pilot's visor and provide high-angle, off-boresight targeting.

Inputs from six common, distributed aperture system (DAS) sensors are designed to create a 360-degree protective IR sphere around the airplane, providing the pilot approximately 20/40 vision acuity and allowing airplanes to fly in closely spaced nighttime combat spreads. The pilot will be able to look down to "see" the scene below the aircraft, through darkness, smoke and dust, projected on the helmet visor. DAS, the latest in IR-based missile warning and situational awareness tools, is complemented by EOTS, the internally mounted electro-optical targeting system. EOTS provides a smaller field of view but longer-range targeting. Under the command of the mission software, EOTS could provide range to a target without turning on the radar.

Fourth-Generation Radar

The F-35's fourth-generation active electronically scanned array (AESA) radar is designed to reduce by half the cost and weight of third-generation technology, deployed in emerging platforms such as the F/A-22. The JSF radar, for example, uses "twinpack" T/R modules, consolidating two into one package. The AESA system's lifespan is projected to be "well over" 8,000 hours, the typical life of a fighter aircraft, says Robert Thompson, director of JSF combat avionics for radar developer Northrop Grumman Electronic Systems.

In air-to-surface operations the radar will support functions such as synthetic aperture radar (SAR) ground mapping and inverse SAR for ship classification. In air-to-air operations, the sensor will support features such as cued search, passive search and multitarget, beyond-visual-range tracking and targeting. Because the beam can move from point to point in millionths of a second, a single target can be viewed as many as 15 times a second.

JSF's powerful sensor suite will allow the aircraft to assume an active role in the tactical "infosphere," company officials assert. "The tactical fighter used to be at the end of the food chain," receiving information from special-purpose sensor aircraft, Thompson says. But it became obvious, from the quality of JSF sensor data and the number of planes to be fielded, that they will be "a major feed of tactical information."

The sensors have gone through preliminary design review (PDR) and are heading toward critical design review (CDR) over the next six months. Critical design work, on the hardware side, emphasizes areas such as component reliability, cost and ruggedness, and final board layouts.

Wrapping Sensors Up

Mission systems software, still in early development, will be key to the F-35's success, sifting, fusing and presenting sensor data "so that it is inherently obvious to the pilot what the course of action should be," asserts Jon Waldrop, director of international programs for prime contractor Lockheed Martin. The software "wraps [the sensors] up into a functional architecture that allows them to smartly work together, cross-cue and take advantage of fused information to help the pilot," Thompson explains.

The crucial data fusion function has been identified as a program-level risk, which means that senior officials will track its progress, says Air Force Lt. Col. Jim Baker, F-35 mission systems lead. A risk-reduction effort is under way. Flight testing was scheduled to commence in August or September, using current versions of the radar and EOTS system on Northrop Grumman's BAC-111 test aircraft, according to Steve Foley, tactical information systems lead with the JSF program office.

"The government pushed on Lockheed to start fusion flying early," Thompson says. The idea is to look at baseline algorithms, prove out algorithm development and simulation tools, and confirm basic architectural concepts, explains John Harrell, Lockheed Martin's tactical information systems lead. The risk reduction flight program is expected to run about six months, with analysis of the results feeding into on-going fusion algorithm studies.

The approximately 4.5 million lines of mission systems code will be developed in block upgrades. Early versions of data fusion algorithms will be examined in the risk reduction program. "Fusion really starts hitting in 2007, when we start doing fusion of all onboard sensors," Harrell says. Fusion capabilities will continue to increase with the Block 3 mission software release to flight test in mid-2010, adding information from offboard sources.

Mission systems functions are organized around the concept of a continuous "OODA loop," which stands for observe, orient, decide and act. Sensors and data links will acquire data, which will be fused in the ICP, activating tactical decision aids?or "planners." Search, attack, avoidance and denial planner modules would work simultaneously on the fused data, producing action plans for the pilot.

The search planner is intended to help pilots locate targets. This software application would look, for example, at all the possible places where a column of tanks could be, based on factors such as the last siting, the road network, terrain and the speed of the vehicles.

Although the details of pilot/software interaction are far from mature this early in the program, Baker describes one search planner scenario. The software module would ask the group leader?digitally or audibly?how many F-35s are on the mission? If the lead says, or indicates, "four," a grid would pop up to show where each wingman should be for optimal searching. Similarly, the search planner would overlay the possible locations of the tank column on a map for the pilots in the JSF formation.

After the tanks have been located, the attack planner could plan the ingress route, assess the vulnerability of the tanks, and indicate where the wingmen should be. While these tasks are proceeding, a "fast track" process would send any high-priority threat information directly to the pilot, who would determine, with the help of an "avoid planner," the evasion route. Although still a long way from realization, these processes would execute in fractions of a second, permitting pilots in a multiship formation to counter or avoid multiple threats and at the same time attack multiple targets.

Lockheed plans to hold several "pilot simulation events" to evaluate the mechanization and utility of these functions, i.e., what the pilot can do well and what is best handled by onboard computers.

A portable memory device from Smiths Aerospace?designed to provide hundreds of gigabytes of nonvolatile storage?will help the pilot load mission plan data and record video and other information in flight. Smiths also will provide a second, permanently installed mass memory device and an airborne file server.

Core Processor

Hosting the mission systems software is the JSF's electronic brain, the ICP. Packaged in two racks, with 23 and eight slots, respectively, this computer consolidates functions previously managed by separate mission and weapons computers, and dedicated signal processors. At initial operational capability, the ICP data processors will crunch data at 40.8 billion operations/ sec (giga operations, or GOPS); the signal processors, at 75.6 billion floating point operations (gigaflops, or GFLOPS); and the image processors at 225.6 billion multiply/accumulate operations, or GMACS, a specialized signal processing measure, reports Chuck Wilcox, Lockheed's ICP team lead. The design includes 22 modules of seven types:

Four general-purpose (GP) processing modules,
Two GPIO (input/output) modules,
Two signal processing (SP) modules,
Five SPIO modules,
Two image processor modules,
Two switch modules, and
Five power supply modules.
The ICP also will have "pluggable growth" for eight more digital processing modules and an additional power supply, Wilcox adds. It uses commercial off-the-shelf (COTS) components, standardizing at this stage on Motorola G4 PowerPC microprocessors, which incorporate 128-bit AltiVec technology. The image processor uses commercial field programmable gate arrays (FPGAs) and the VHDL hardware description language to form a very specialized processing engine.The ICP employs the Green Hills Software Integrity commercial real-time operating system (RTOS) for data processing and Mercury Computer Systems' commercial Multi-computing OS (MCOS) for signal processing. Depending on processing trades still to be made in the program, the JSF also could use commercial RTOSs in sensor front ends to perform digital preprocessing, according to Baker. The display management computer and the CNI system also use the Integrity RTOS. COTS reduces development risk and ensures an upgrade path, according to Ralph Lachenmaier, the program office's ICP and common components lead.

Tying the ICP modules together like a backplane bus and connecting the sensors, CNI and the displays to the ICP is the optical Fibre Channel network. Key to this interconnect are the two 32-port ICP switch modules. The 400-megabit/sec IEEE 1394B (Firewire) interconnect is used externally to link the ICP, display management computer and the CNI system to the vehicle management system.

Low-level processing will occur in the sensor systems, but most digital processing will occur in the ICP. The radar, for example, will have the smarts to generate waveforms and do analog-to-digital conversion. But the radar will send target range and bearing data to the ICP signal processor, which will generate a report for the data processor, responsible for data fusion. Radar data, fused with data from other onboard and offboard systems, then will be sent from the ICP to the display processor for presentation on the head-down and helmet-mounted displays.

EW System

The electronic warfare suite, integrated by BAE Systems, includes:

All-aspect radar warning capability, supporting analysis, identification, tracking, mode determination and angle of arrival (AOA) of mainbeam emissions, plus automatic direction finding for correlation with other sensors, threat avoidance and targeting information;
Defensive threat awareness and offensive targeting support?acquisition and tracking of main beam and side lobe emissions, beyond-visual-range emitter location and ranging, emitter ID and signal parameter measurement;
A multispectral countermeasures suite with countermeasures response manager function, standard chaff and flare rounds; and
Passive EW apertures.
The EW suite complements the field-of-view and frequency coverage of the radar by providing complete coverage around the aircraft at a wider frequency range. Passive radar warning system apertures?at three different frequency ranges?are embedded in the skin of leading and trailing wing edges and horizontal tail surfaces. The EW system also can use the radar antenna for electronic support measures (ESM). Expected mean time between failure (MTBF) is 440 hours.

The radar warning system is active all of the time, providing both air and surface coverage. Packaged in two electronics racks, it includes cards for radar warning, direction finding and ESM. The system uses DAS inputs directly, as well as fused inputs from the ICP. Digital processing allows reprogramming and increases reliability.

Vehicle Management System

One of the most important non-ICP processing functions is the vehicle management system, which handles flight control and utility systems such as fuel management and electrical and hydraulic system controls. BAE Systems designed the vehicle management computer (VMC), three of which are connected together via an IEEE 1394B bus. About the size of a shoe box, each computer contains a processor card, I/O card and power supply card.

All three VMCs process data simultaneously, constantly comparing results across channels to assure data integrity. In the case of divergent data, two processors can "vote" one processor or signal out, explains Bill Dawson, JSF program manager for BAE Systems Aerospace Controls.

Interfacing to the VMCs are remote I/O units provided by Smiths. These devices?10 per aircraft?are an integral part of the vehicle management network, receiving flight control and other inputs from hundreds of digital, analog and discrete sources, processing the data and outputting the results to the VMCs over the 1394 bus.

Head-Down and Helmet Displays

The Joint Strike Fighter's flight deck display moves beyond the F/A-22's multifunction display-type layout to a single, panoramic, 8-by-20-inch viewing area, the largest ever in a fighter aircraft. Developed by Rockwell Collins (Kaiser Electronics), the multifunction display system (MFDS) comprises two adjacent 8-by-10-inch projection displays, each with a resolution of 1280-by-1024 pixels. Each half is fully functional, so the system can continue to operate if one half fails.

The MFDS will present sensor, weapons and aircraft status data, plus tactical and safety information. The viewing area can be presented as a large tactical horizontal situation display or be divided into multiple windows.

Functions are accessed and activated by touch?the first touch screen on a large-format display?or by hands-on-throttle-and stick (HOTAS) commands. Each 8-by-10-inch area has an integrated display processor for low-level data crunching and a "projection engine" to cast the image onto the screen. The MFDS uses micro-active matrix liquid crystal display (LCD) image sources?three per projection engine?illuminated by arc lamps. Collins will provide the display drivers and the first layer of services software, which Lockheed Martin will use to implement display applications.

Collins will procure glass commercially, tempering it with proprietary chemical processes. The Collins display processor _circuit card assembly design also is used for the display management computer-helmet (DMC-H). The assembly uses Collins application-specific integrated circuits (ASICs), as well as commercial processors, memory and graphics chips. Flight qualification and safety testing will begin once initial display systems are delivered in the second quarter of 2004. Standby 3-by-3-inch active matrix LCD flight displays are provided by Smiths Aerospace.

The F-35's helmet-mounted display system (HMDS) will replace the traditional head-up display (HUD), "allowing for a tremendous cost savings and, more importantly, weight reduction," asserts Louis Taddeo, director of business development with HMDS designer, Vision Systems International (VSI). VSI is a joint venture partnership between Collins and EFW Inc., an Elbit Systems Ltd. subsidiary.

The HMDS uses a combination of electro-optics and head position and orientation tracking software algorithms to present critical flight, mission, threat and safety symbology on the pilot's visor. The system allows the pilot to direct aircraft weapons and sensors to an area of interest or issues visual cues to direct the pilot's attention, Taddeo explains. The HMDS comprises the helmet-mounted display, DMC-H, and helmet tracking system. VSI also supplies the joint helmet-mounted cueing systems used on the F-15 and F/A-18E/F aircraft.

Fundamental requirements for the HMDS include visor-projected, binocular, wide field-of-view, high-resolution, near real-time imagery and symbology; equivalent accuracy to head-up display systems; 24-hour usability; and fit, comfort and safety during ejection. Proper weight and balance are crucial in minimizing pilot fatigue resulting from high-g maneuvers and reducing head and neck loads in ejections, Taddeo stresses. The F-35 helmet is expected to weigh 4.2 pounds (1.9 kg).

The F-35's HMDS employs a flat panel, active matrix LCD, coupled with a high-intensity back light, as its image source. The partially overlapped display provides a binocular image 50 degrees wide by 30 degrees high.

The digital image source provides both symbol writing and video capability. The system includes a clear, optically coated visor for night operations and a shaded visor for daylight operations. Imagery is provided via the distributed aperture system (DAS) or a helmet-mounted day/night camera. F-35 pilots can select imagery and symbology via HOTAS commands.

F-35's CNI System

The two-rack communications, navigation and identification (CNI) system processes waveforms internally, sending high-level status data to the core processor. The CNI system is designed to provide functions such as beyond-visual-range identification friend-or-foe (IFF); secure, multichannel, multiband voice communications; and intraflight data link (IFDL) exchanges, synchronizing the displays of multiple aircraft. The CNI suite will support 35 different com, nav and identification waveforms?about 5 pounds (2.26 kg) per waveform function, compared with the legacy black box approach of 10 to 30 pounds (4.54 to 13.6 kg), or more, per waveform, according to Frank Flores, JSF program director for Northrop Grumman Radio Systems.

Software-defined radio technology means that the suite can provide numerous radio functions?ranging in frequency from VHF to K band?from a set of more general-purpose module types, including:

Wideband RF module, performing analog-to-digital conversion, waveform processing and digital signal processing.
Dual-channel transceiver module, which can receive and digitize waveforms over a wide frequency band and generate waveforms for transmission, driving power amplifiers. This module supports most of the 35 waveforms.
Frequency-dependent power amplifiers, including L-band, VHF/UHF, and higher-frequency units.
Power supply module.
CNI processor module, which performs signal processing, data processing and comsec processing.
And an interface module.
Northrop Grumman developed middleware, located between the operating system and the applications. This layer of software is designed to allow smooth system growth and compatibility with Joint Tactical Radio System (JTRS) waveforms.

The CNI suite uses Green Hills Software's Integrity commercial real-time operating system, PowerPC processors, field programmable gate arrays and digital signal processors. Radio Systems is streamlining the design to minimize footprint.

Some of the suite's baseline functions include: VHF/UHF voice, HaveQuick I/II, Saturn (HQ IIA), satcom T/R, IFF/SIF (selective ID feature) transponder, IFF Mode IV interrogator, ILS/MLS/MLS/Tacan, IFDL, Link 16 T/R, Link 4A, tactical data information link (TADIL-K), 3-D audio, TACFIRE/Air Force applications program development (AFAPD), and ADS-B.

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Lasers Being Developed For F-35

Lockheed Martin is tailoring a laser for the F-35 Joint Strike Fighter that could be ready as early as 2010 for demonstration and the start of a full-scale development program.

Variants of the solid-state laser, powered by a drive shaft from an aircraft's engine instead of batteries, also are being considered for use on AC-130 gunships and Lockheed Martin-designed unmanned aircraft. The high-energy laser system is being designed in a joint project with Raytheon.

An advantage of a directed-energy weapon is that it can shoot indefinitely and is limited only by the ability to cool it, and it's covert. "There's no huge explosion associated with its employment," a Lockheed Martin official said. "There are no pieces and parts left behind that someone can analyze to say, 'This came from the U.S.' The damage is very localized, and it's hard to tell where it came from and when it happened. It's all pretty mysterious."

A foe would be left largely clueless trying to analyze what happened and why. Planners envision scenarios where fires are set, electronic components are damaged and computer memories are erased with no collateral damage or injury to those near the target.

A Defense Science Board study last year said that several technology breakthroughs have moved high-energy lasers on fighters into the realm of the possible. Among them was increased electrical power-generation capability achieved under the "More-Electric Aircraft Project." The DSB contends that aircraft systems will be able to provide one megawatt of power in less than five years. Other rapidly developing technologies allow smaller packaging of systems. These include advanced solid-state lasers, chemical lasers with electro-regeneration of chemicals and fiber lasers.

The technical hurdles include compensating for vibrations and high g-forces that can punish the laser and beam-control system and turbulence around the aircraft. "The beam control system must be extremely dynamic to account for these fast transient processes occurring at kilohertz rates," the report said.

Lockheed Martin looked at laser concepts from TRW, Boeing and Textron, but Raytheon's appeared to be the most advanced, a company official said. Raytheon's solid-state design is "particularly suitable for JSF because it's very compact and shows promise for achieving the necessary power levels and beam quality," the Lockheed Martin official said. "The other companies don't appear to feel as confident in their ability to buy or develop a suitable laser." Company officials are also hoping that the Air Force Research Laboratory's directed-energy directorate at Kirtland AFB, N.M., or the Defense Advanced Research Projects Agency would fund some of the solid-state laser development.

A first-generation laser weapon would be able to engage aerial targets such as cruise missiles and enemy aircraft, as well as ground targets such as antiaircraft missile sites and ground vehicles. These capabilities would likely require laser power of 100 kw., analysts predict.

"That's about the minimum threshold to be a weapon," the Lockheed Martin official said. "Less than that and it's only useful against soft targets. One hundred kilowatts would also let targets be engaged at tactically significant ranges."

Except for self-defense, laser weapon designers think the minimum effective range is about 6 mi. for a fighter aircraft. As the power of solid-state lasers improves with the maturation of new technology, the range of directed-energy weapons would increase. Ideally, the laser-equipped aircraft would also carry conventional munitions. The F-35, for example, won't give up any weapon-carriage capability when the laser is installed, and it will allow a combination of effects. Lasers can provide low collateral damage and covert attack. Conventional weapons would provide longer range strike.

"Laser and HPM [high-power microwave] weapons are more like an avionics system," a company official said. "You don't go out, drop three and go home. It's always on the air vehicle, you use it when you want and, at least with solid-state technology, you're not going to run out of power."

The concept for F-35 is to have a turret, centered on the lift-fan cavity, which would extend when needed from the bottom of the aircraft. The system would be installed in the space just aft of the cockpit that was carved out to hold the vertical lift fan. With a single turret, the directed-energy weapon would be most effective against ground targets, low-flying airborne targets and for self-defense.

While conceptually the one-turret aircraft could be maneuvered to fire at other aircraft or air-to-air missiles, planners are dubious. "There's not always time to maneuver, especially in close-in self-defense situations, so you want multiple apertures," a Lockheed Martin official said. Therefore, company designers are considering a second turret that would extend from the top of the lift-fan space to cover the upper hemisphere around the aircraft. They don't yet know if they can make both turrets fit into the space that they must share with target trackers, laser, optics, power and cooling. "It will be a trade of coverage versus internal volume," he said. There also would be the option of flying a mix of aircraft, some specialized for air-to-air and others for ground attack. For demonstration purposes, the laser system would likely be installed first on a pod and later on an early model JSF airframe.

Lockheed Martin believes it has a distinct advantage in getting directed-energy weapons into the field because the F-35's unique design will allow it to supply a great deal of electrical power. Instead of having to rely on heavy, short-lived batteries to run the laser, it will be fed electrical power generated by a drive shaft run from the main engine. In the Marine Corps' short-takeoff, vertical-landing version of the F-35, the drive shaft will power the vertical lift fan. But for the Air Force and Navy versions, the empty spaces designed for the lift fan and cannon could be used for the laser weapon.

"The drive shaft has the [potential] of producing multi-megawatts of power in real time without hurting the aircraft's performance," the Lockheed Martin official said. The shaft from the engine can produce more than 27,000 shp. to drive a generator. But the rate of fire and recycle time for a laser weapon, particularly against targets at long range, may be limited by the need for thermal cooling. "You can't fire forever," he said. "The challenge is doing the cooling in near real time." What the duty cycle will be has still to be determined, but some specialists suggest that at least initially it might be a 4-sec. burst, followed by 4 sec. of cooling, then another 4-sec. burst and finally a 30-sec. cool-down before engaging two more targets.

Directed-energy, self-defense weapons with a fast recycle time for multiple shots (since two or more antiaircraft missiles are usually fired together) is considered a key concept for future warfare. By 2025, many U.S. Air Force planners believe multispectral sensor technology will overtake the ability of stealth designs to protect aircraft from air defenses.

Directed-energy weapons fall into two categories so far: high-energy lasers and HPM. Farther in the future is a plasma of ionized gas molecules that might resemble a bolt of lightning.

Lasers use thermal effects to quickly blow holes in targets, and they are being designed for use in manned aircraft, say Air Force and aerospace industry officials. A laser beam can be focused on a fuel tank to produce catastrophic damage, or it can be focused on a vehicle's engine to simply disable it. Generally, however, it is a lethal, longer range weapon.

HPM is most effective in attacking electronics, particularly computers where spikes of high power can damage components and erase computer memories. This kind of technology is seen as the weapon of choice for unmanned aircraft because spurious emissions might affect safety of flight

http://www.aviationnow.com/content/publ ... 8/aw32.htm
http://www.afa.org/magazine/dec2002/1202attack.asp

If any one have any more info about the cool things the avionics and subsystems of the F-35 ... please post.

Ok why would you need a Stealth platform to fire a Laser? the turret sounds something more suted to an AC-130 Laser Gunship!! who needs Chaff and flairs when can Zap it. with the weight problems on the Current airborn laser I dont see this happening anytime soon. and its flown on a 747!!!

Quote:

Ok why would you need a Stealth platform to fire a Laser? the turret sounds something more suted to an AC-130 Laser Gunship!! who needs Chaff and flairs when can Zap it. with the weight problems on the Current airborn laser I dont see this happening anytime soon. and its flown on a 747!!!

The ABL is designed to tag ballistic missiles at extreme long range >500 mi. This laser is for short ranges <6 mi. The technologies involved are also very different. The ABL uses a fuel source. This thing uses the engine to power a generator to run the laser; very much like the LANTIRN is powered by the aircraft.

Also the technology is still a concept. If they think it can't be done then they would just cancel it. However what is more important for the JSF is to meet cost and performance requirments for initial operation.

At this point the JSF is struggling with weight issues - anything that adds weight to the jet is just wishful thinking at the moment.

Exactly, I think all these things are for the future. Currently the efforts should be considered on reaching the fielding goals for the basic jsf platform.

bring_it_on1 wrote:

Exactly, I think all these things are for the future. Currently the efforts should be considered on reaching the fielding goals for the basic jsf platform.

And even those basic's are not fully defined yet. I flew the JSF Demonstrator simulator and although it basicly has all the features (like the HMD) it was very clear LM is still in the process of designing. So a lot can and will change untill they reach production.

BTW, thanks bring_it_on, for posting the article. good info!

most of the basics are either frozen or in the process of being frozen....the external design just got frozen and the avionics and su-systems will get frozen later this year.....

So is it still a twin-tail design? I heard they were evaluating a single tail design as part of the weight reduction studies...

why have a tail at all!!

SwedgeII wrote:

why have a tail at all!!

C'mon... where would they paint their squadron markings???

That grafitti on the B-2 gear doors just doesn't cut it IMO... Razz

A lot of antennas and sensors are probably located inside the rudders, so one is probably an advantage bigger than the possible stealth and drag disadvantage of having a rudder in the first place. The other problem they then will have to sort is possibly adding speed brakes, as I am sure they use, like the F/A-22, a combination of the rudders, horizontal and roll stabiliser move to brake now. Then the question is; are all the other control surfaces big enough to do the roll control they need if it does not have the help of one or two rudders.

They could of course have a tail like the YF-23 that perhaps would help solve most needs, except perhaps a location for sensors and antennas.

Well the McDonald Douglas design for the jsf was to be quite similar to the northrop's assembly with the entire tail mobile... it was thrown out because its propulsion system was too high risk (I think Mc Douglas was still not Boeing by then)....there have been some changes made to the X-35 due to weight and aerodynamic considerations... as well as the weapon bays have been made convex inwards so that larger weapons can be accomodated as well as small fuel tanks can be put inside the weapon bays during ferry flight....

A computer rendering shows the USAF production model. Inlets were moved aft to improve visibility for the pilot, and the overall airplane grew seven inches to permit room for growth in avionics.

Forum: F-35 Design & Construction

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