YAK-141 Vs F-35 JSF

-Yak-141 has a similar radar to the Mig-31, with a similar look down shoot down capability.
-F-35 has the advantage of stealth, but not much overall
-YAK-141 has higher speed advantage
-F-35 is most likely more expensive
-Agility is unknown.

Yak-141 Freestyle

http://www.globalsecurity.org/milita...ia/yak-141.htm


The Yak-141 (formerly Yak-41) was intended originally to replace Yak-38 for air defence of Kiev class carriers/cruisers, with secondary attack capabilities. Designed for carrier-borne operations as an air interceptor, close air combat, maritime and ground attack aircraft, the Yak-141 has the same multi-mode radar as the MiG-29, although with a slightly smaller antenna housed in the nose radome. It features a triplex full authority digital fly-by-wire system.

The Yak-141 continues previous Soviet V/STOL principles, combining a lift and propulsion jet with two fuselage mounted lift jets in tandem behind the cockpit, with cruise power provided by a single Tumansky R-79 jet engine. The R-79 has a rear lift/cruise nozzle which deflect down for take-off while the two lift engines have corresponding rearward vector to ensure stability. The airframe makes extensive use of composites materials, with some 28 percent by weight constructed of carbon-fibre, primarily in the tail assembly, while the remainder of the structure is mainly aluminum lithium alloys.

The project began in 1975, but was delayed by financial constraints as well as the protracted development of the engine, which meant the prototype did not fly until March 1989. This development program was cancelled due to termination of Defence Ministry funding. Yakolev OKB continued development in refined land-based and naval combat aircraft forms. Four prototypes were built, two continuing in flight testing until 1995, with the other two used for engine and structural testing. To facilitate sales of the Yak-141, Yeltsin has issued decrees allowing tri- or quadripartite agreements with a number of interested organizations in Latin America and Asia.

AC's Specifications

Country of Origin Russia
Builder Yakovlev
Role: air defence
Span 33ft 1 1/2in (10.105m); folded, 19ft 4 1/4in(5.9m)
wing area 341.56ft(2) (31.7m(2))
length overall 60ft 2 3/4in (18.36m)
height 16ft 4 1/4in (5m)
wheel track 9ft lOin (3m)
wheel base 22ft 9 1/4in (6.945m)
tailplane span 19ft 4 1/4in (5.9m)
Weights 25,684lb (11,650kg) Empty, equipped 34,833lb (15,800kg) VTO max take-off weight 42,990lb (19,500kg) STO max take-off weight

Loads 2,204lb (1,OOOkg) VTO max external load 5,732lb (2,600kg) STO max external load 3,858lb (1,750kg) max external fuel
Armament

• 30 mm cannon
• AA-10 Alamo radar-guided medium-range AAM
• AA-11 Archer shortrange IR-guided missile
• bombs
• unguided rockets

limiting load factor 50% fuel, 7g.
Accommodation Single pilot in a Zvezda K36V rocket-boosted zero-zero ejection-seat.

Power Plant

• One Kobchenko/Soyuz R-79-300 vectored-thrust lift/cruise turbofan developing 34,170lb (15,500kg) with afterburning for conventional take-off, or 23,148.5lb (10,500kg) dry, plus
• two Rybinsk RD- 41 turbofan lift engines each rated at a maximum 9,039lb (4,100kg)

Max internal fuel capacity 9,700lb (4,400kg)

Maximum Speed 675 kts (1,250km/hr) Max level speed, sea level
971 kts (1,800km/hr) at 36,089ft (11,OOOm) M=1.8 max achievable Mach numbe

vertical climb rate 49,213ft/min (250m/sec)
service ceilingover 49,000ft (15,000m+)

combat radius

• 351nm (650km) VTO range at sea level, no external weapons
• 372nm (690km) with 4,409lb (2,000kg) weapon load and take-off run of 394ft (120m)
• 755nm (1,400km) at 32,808-39,370ft (10-12,000m)
• 1,133nm (2,100km) max range, with external fuel and short take-off
• 755nm (1,400km) with vertical takeoff and internal fuel

A stealthier varient of the Yak 141 has been proposed.



JSF



http://www.globalsecurity.org/milita.../jsf-specs.htm

Function strike fighter
Contractor Lockheed-Martin (Boeing lost the contract)
Service U.S. Air Force U.S. Marine Corps U.K. Royal Navy U.S. Navy

Variants
Conventional Takeoff and Landing (CTOL) Unit Cost $28M
Short Takeoff and Vertical Landing (STOVL) Unit Cost $35M
Carrier-based (CV) Unit Cost $38M

Inventory Objectives U.S. Air Force 2,036 aircraft U.S. Marine Corps 642 aircraft U.K. Royal Navy 60 aircraft U.S. Navy 300 aircraft
Inventory Objectives 1,763 aircraft 609 aircraft 480 aircraft
Propulsion Baseline: P&W F119-PW-100 derivative from F-22r
Alternate Engine: General Electric F120 core Thrust



Empty Weight ~22,500 lbs(USAF) ~24,000 lbs U.S. Navy
Internal Fuel 15,000 lbs(USAF) 16,000 lbs U.S. Navy
Payload 13,000 lbs(USAF) 17,000 lbs ( U.S. Navy)
Maximum Takeoff Weight ~50,000 lbs
Length 45 feet
Wingspan 36 feet(USAF) 30 feet Height( U.S. Navy)
Ceiling ?
Speed supersonic USAF
Combat Radius over 600 nautical miles (USAF)
Crew oneUSAF
Armament ?
First flight 1999 USAF
Date Deployed 2008 USAF



The F-35's ability to win an air-to-air engagement is drawing increased attention as the U.S. military and industry's focus includes expanding the Joint Strike Fighter's customer base beyond the core purchasing nations.

For years, prime contractor Lockheed Martin seemed content to promote the F-35's "strike fighter" capabilities, if only to avoid competing against its other major fighter program, the F-22 Raptor. But with the F-22 not exportable, Lockheed Martin seems keen to talk up the F-35's air combat skills to bolster its chances for new foreign military sales -- namely, to Japan, Turkey and Greece.



The contractor tells Aviation Week that the JSF's combination of stealth, multisensor situational awareness, advanced pilot-machine interface and basic aeromechanical performance make it a credible fighter aircraft, too. That is key to several other customers, who cannot afford the so-called high-low fighter mix on which the U.S., U.K. and Italian air forces are planning.

But Lockheed Martin is focusing largely on the beyond-visual-range fight, with ranges greater than 18 naut. mi. that executives say will represent 62% of all aerial combat. Another 31% of engagements would fall into the 8-18-naut.-mi. transition range, and just 7% of fighting would be close-in combat where the airframe is stressed the most.

Lockheed Martin says it ran the F-35 through the Pentagon's TAC Brawler simulation for air combat systems analysis, using what would be the "ideal" air combat configuration, taking the conventional-takeoff-and-landing F-35A, the only model designed to perform full 9g maneuvers.

The aircraft can also reach a 55-deg. angle of attack in trimmed flight, while most fighters, excluding the F/A-18, are limited to 30 deg. The exact performance of the current F-35A configuration -- also known as the 240-4 -- are classified. But a similar earlier standard (240-3) was credited with a maximum speed of Mach 1.67; acceleration from Mach 0.8 to Mach 1.2 at 30,000 ft. in 61 sec.; a top turning speed of 370 kt. at 9g and 15,000 ft.; and a sustained turn capability of 4.95g at Mach 0.8 and 15,000 ft. Moreover, an aircraft with those performance figures would carry two beyond-visual-range AIM-120 Advanced Medium-Range Air-to-Air Missiles (Amraams) in the internal weapons bay.



Yet, such performance numbers appear to leave the F-35 short of the kind of air-to-air capabilities provided by other combat aircraft, such as the Russian Su-30MKI or the European Typhoon. And even Lockheed Martin test pilots concede that the F-35 -- although offering very high initial acceleration due to its powerful 42,000-lb.-thrust F135 engine -- could start losing advantage at higher speed and altitude. This might be partly due to the aircraft's large frontal area, which is designed to allow internal weapons carriage -- meaning in a traditional quick-reaction intercept role, the F-35 may not be able to match rivals.

Nevertheless, Brawler modeling showed the F-35 could achieve a loss-exchange ratio better than 400% against its nearest "competitor," according to Lockheed Martin executives. They demur about naming the competitor, but their comparison charts indicate it is the Sukhoi Su-30 or Typhoon.

That engagement ratio comes from the combination of F-35 characteristics, executives argue, including stealth, the performance of the APG-81 active electronically scanned array radar, sensor fusion using data links and the 360-deg. situational awareness afforded by the distributed aperture system of infrared and electro-optical sensors and electronic support measures.

In the meantime, and without discussing specific performance characteristics, Italian air force fighter pilots involved with the F-35 program tell Aviation Week that the aircraft's performance falls "between the F-16 and the F/A-18 in terms of flight envelope -- and is actually closer to the F/A-18, considering its high angle of attack and slow-speed maneuvering capabilities."

The F-35A, with an air-to-air mission takeoff weight of 49,540 lb., has a thrust-to-weight ratio of 0.85 and a wing loading of 110 lb. per sq. ft. -- not ideal for a dog-fighter. The F135 engine delivers 42,000 lb. thrust, and industry officials suggest that an F-35 entering an air-to-air engagement with 40% -- or more than 7,275 lb. -- of internal fuel will have a thrust-to-weight ratio of 1.09 and a wing loading of 83 lb. per sq. ft. Those figures describe an agile, albeit not top-end, fighter.



Still, one key feature, Lockheed Martin executives stress, is the very low observability designed into the JSF. Whereas the F-35 would carry its weapons internally, the Typhoon, Su-30, Saab Gripen or Dassault Rafale carry their missiles externally, thus increasing their radar signatures and degrading their on-paper air-to-air performance. The F-35 also accommodates more internal fuel, 8.3 tons, giving it greater endurance potential without external fuel tanks that would affect radar signatures.

Nevertheless, the F-35 may have notable weaknesses for pure air-to-air combat. For one, it is not designed to conduct engagements in a high-speed, high-altitude, sustained turning environment. Its high-speed cornering capability should help it to dodge an adversary's beyond-visual-range missiles, though, particularly if German and U.K. air-to-air simulations on the kill probability of modern medium-range air-to-air missiles are accurate.

Those figures are part of the rationale for countries pursuing the ramjet-powered MBDA Meteor missile to supplant Amraams. Yet even in the Amraam world, Typhoons may have an edge over the F-35, since they could launch the missile at higher speed. Sukhoi Su-30s and the future T-50 are also being designed to maximize air-to-air missile performance that way.

Finally, while Lockheed Martin touts F-35 stealth as an advantage, it has its drawbacks, as well. The aircraft's payload is limited as long as it wants to preserve its low-observable signature through internal carriage. That means having only four AIM-120s at its disposal. A study now underway could boost that total to six Amraams. Other weapons, including infrared-guided air-to-air missiles, would be carried externally, with plans for a "stealthy" JSF adaptation using a low-signature pylon design. Still, the radar signature would increase, as would drag, further reducing the F-35's potential.

It is not clear how critical such perceived shortcomings truly are. Some pilots argue that in a dogfight, the air-to-air missile has more to do with the engagement's outcome than does the aircraft.



Engine type

F-35/JSF uses same engine principles as Yak-141 and constructed on scheme of Yak-141.
Lockheed is now developing its operational version of the concept as a supersonic multirole aircraft to replace the Harrier.

The Yak-141 had its maiden flight some 25 years ahead of the timeframe set by foreign manufacturers for creation of such a plane. After the show in Farnborough, Yakovlev design bureau worked together with Lockheed on Joint Strike Fighter (JSF) programme. As a result,
Lockheed's final JSF proposal resembles... the Yak-141M.

During the summer of 1995, Lockheed Martin announced a teaming arrangement with Yakovlev to assist in the former's bid for the JAST (Joint Adanced Strike Technology) competition. Yakovlev's knowledge of jet lift technology was to prove invaluable. Lockheed Martin was
subsequently selected to build a demonstrator aircraft, the X-35, which went on to win the JSF (Joint Strike Fighter) competition and will soon become a production fighter as the F-35.

The swiveling rear exhaust is a licensed design from the Yakovlev design bureau in Russia, which tried it out on the Yak-141 STOVL fighter.

The lift fan approach had the advantage that it minimized hot exhaust ingestion back into engine, a common problem with STOVL designs that robs them of vertical thrust. The scheme was similar to that pioneered by the Russian Yakovlev Yak-141 "Freestyle" STOVL fighter, which did not enter production.

"The exhaust from the engine flows through the 3 Bearing Swivel Nozzle (3BSN). The 3BSN nozzle, developed by Rolls-Royce, was patterned along the lines of the exhaust system on the Yakovlev Yak-141 STOVL prototype that flew at the 1992 Farnborough air show."

"In 1995, Lockheed Martin signed an agreement with the Russian Yakovlev Design Bureau and Pratt & Whitney signed one with the Soyuz Aero Engine Company for information on the supersonic Yak-141 STOVL fighter and its three bearing swivel duct nozzle. However, Lockheed apparently did not benefit from the agreement and their return on the investment was negligible."

I haven't read anything else about the return on the investment being 'negligible'. As it is I think the statement is quite suspect: "yes we purchased the engine technology from the designers of the world's first STOVL fighter, but no, we didn't get much out of it".

"In 1992/93 Lockheed contracted Yakovlev on some work pertaining to short take-off/vertical landing (STOVL) aircraft studies in reference to the JAST (JSF) project. Yakovlev shared its STOVL technologies with the US company for several dozen million dollars.


"Former Yakovlev employees accuse Yakovlev heads of taking personal interest out of the deal with Lockheed, because the official sum of the contract did not correspond with the value of the information presented to the US company. The data was on the Yak-141 test program, aerodynamics and design features, including the design of the R-79 engine nozzles.



After a careful study of those materials, Lockheed - without much noise - changed its initial JSF proposal, including a design of the engine nozzles that is now very similar to those of the Yak-141."

"Lockheed Martin's X-35 design has a trapezoidal wing planform which initially featured foreplanes, although these since deleted; STOVL version embodies a lift fan, shaft-driven by a modified F119 with a vectoring lift/cruise nozzle developed by Rolls-Royce; lift fan replaced by extra fuel in the CTOL version. Lockheed Martin also turned to Russia for technical expertise, purchasing design data from Yakovlev; and used an 86 per cent subscale model (originally developed for the CALF project and fitted with a Pratt & Whitney F100-PW-220 engine plus an Allison shaft-driven lift fan) for testing"



The Yak-141, being the world's first supersonic STOVL (short take-off/vertical landing) aircraft, has three engines: one lift-cruise R-79 with a thrust of 15500kg and two small-sized RD-41 of 4100kg each. The powerplant allows the plane to lift off vertically with a weight of up to 15800kg. Alternatively, the Yak-141 can perform short take-offs (60-120m) with a weight of up to 19500kg. In the latter case the combat radius increases by 1.5-2 times and patrol time in the combat zone by two times. The pilot can use afterburner even when the nozzles are deflected. The Yak-141's integral flight-control system sets power and deflection of the nozzles so as to optimise making vertical/short take-offs and landings.



Yakovlev Yak-141

The Yak-141M was meant primarily for ground-basing. Introduction of new flight regimes, as well as new take-off/landing techniques, has entailed changes in the airframe, leading to a new design, the Yak-141M. The Yak-141 had its maiden flight some 25 years ahead of the timeframe set by foreign manufacturers for creation of such a plane. After the show in Farnborough, Yakovlev design bureau worked together with Lockheed on Joint Strike Fighter (JSF) programme. As a result, Lockheed's final JSF proposal resembles... the Yak-141M.