AEROSPACE 45
rotating lift fan that is positioned directly behind the cockpit. The lift fan is powered by a drive shaft from the F-35’s single engine, which features a swivelling rear exhaust nozzle that vectors thrust downward during vertical flight. The lift fan, engine and stabilising roll ducts beneath
the F-35B’s wings combine to produce 40 000 pounds of lifting force. Converting the F-35B from STOVL to conventional flight and vice-versa simply requires the pilot to push a button; otherwise the system operates fully automatically. During the conversion from conventional flight
to STOVL flight, doors associated with the STOVL propulsion system open, including the lift fan inlet and exhaust doors, the roll-nozzle doors, the auxiliary-inlet doors on top of the fuselage (which increases the efficiency of the main engine) and the aft fuselage three-bearing swivel duct doors. The three-bearing swivel duct begins vectoring engine thrust downward as well, taking just 2.5 seconds to rotate through 95 degrees. Once all doors are open, the clutch engages and the
lift fan begins turning. As the lift fan reaches full speed the clutch locks, providing a direct drive from the engine to the lift fan. The aircraft control algorithms then begin using the STOVL propulsion system to provide aircraft flight control. While Rolls-Royce is a member of the Fighter Engine
Team with GE on the F136 engine for the F-35, the company is also subcontracted to Pratt & Whitney on the F-35’s alternative engine, the F135, to provide the lift system comprising the lift fan, clutch, drive shaft, roll posts and the three-bearing swivel module (3BSM). Lockheed Martin developed the concept for a STOVL
lift system that uses a vertically-orientated, shaft-driven lift fan (SDLF). A two-stage low-pressure turbine on the engine provides the power necessary to drive the lift fan. The lift fan generates a column of cool air that provides nearly 20 000 pounds of vertical thrust using variable
Fig. 2. Situated behind the cockpit, the F-35B’s lift fan is powered by a drive shaft from the aircraft’s single engine.
inlet guide vanes to modulate the airflow. An equivalent amount of thrust is provided by the downward-vectored rear exhaust. Because the lift fan extracts power from the engine, exhaust temperatures are reduced. In December 2008 Rolls-Royce delivered the first production variable-area vane box nozzle (VAVBN) to Pratt & Whitney for integration on the F-35B. The VAVBN is integral to the aircraft structure and is used to control the lift fan exit airflow when the F-35B operates in powered-lift mode. Installed as one of the first items in the aircraft
assembly sequence, the VAVBN is never removed throughout the service life (8000 flight hours). The MOD plans to operate up to 36 F-35s from each of its two new future aircraft carriers, namely HMS Queen Elizabeth, which is expected to enter service in 2014, and HMS Prince of Wales in 2016. n
LAMINATE SHIMSTOCK HELPS COMPANIES GAIN COMPETITIVE EDGE A
dvances in the bonding and manufacture of laminate shimstock are helping to boost global demand for this product. As the impact of the credit crunch and economic crisis force engineering and manufacturing companies to review and reduce costs, laminate shimstock is being seen as a no risk solution in assisting this process.
Laminate shimstock is available in a variety of materials including brass, steel, aluminium and hybrid in a variety of sizes and thicknesses and is used in the majority of manufacturing and engineering
sectors such as aerospace, railways, power, automotive, construction and other high technology related industries. Laminate Shimstock is multiple layers of foil bonded together to produce a near solid
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material, this allows the functionality of a solid with the benefit of being able to peel individual layers to required thickness. This allows manufacturers to reduce part count, which gives a time and process advantage when assembling components. Examples of uses are where tolerance accumulation is evident, precision alignment is required and where wear compensation is needed. n
Enter 45 or ✔ at
www.engineerlive.com/ede
Ford Component Manufacturing Ltd, is based in South Shields, T
www.fordcomps.co.uk
yne & Wear , UK.
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