Short Takeoff And Vertical Landing Research Articles

Design and piloted simulation of integrated flight/propulsion controls for STOVL aircraft

An integrated flight/propulsion control system has been designed for operation of short takeoff and vertical landing (STOVL) fighter aircraft over the low-speed, powered-lift flight envelope. The control system employs command modes for attitude, flight path angle, and flight path acceleration during transition, and translational velocity command for hover and vertical landing. In this paper, only the longitudinal modes of control are discussed. Piloted evaluations of the control system have been conducted on Ames Research Center's Vertical Motion Simulator. Results indicate that level 1 flying qualities are achieved during transition and vertical landing over a wide range of wind, atmospheric turbulence, and visibility conditions.

Partitioning of centralized integrated flight/propulsion control design for decentralized implementation

The notion of partitioning a centralized controller into a decentralized, hierarchical structure suitable for integrated flight/propulsion control (IFPC) implementation is discussed. A systematic procedure is developed for determining partitioned airframe and engine subsystem controllers (subcontrollers), with the desired interconnection structure, that approximate the closed-loop performance and robustness characteristics of a given centralized controller. The procedure is demonstrated by application to IFPC design for a short take-off and vertical landing (STOVL) aircraft in the landing-approach-to-hover-transition flight phase. >

Flow in a ventral nozzle for short takeoff and vertical landing aircraft

Short takeoff and vertical landing (STOVL) aircraft are planned for possible future development. For these aircraft, the same propulsion system will provide power for lift, hover, and horizontal flight. To accomplish this, many designs include a ventral nozzle to provide part of the vertical thrust required. Understanding and predicting the internal aerodynamic flow caused by a single exhaust duct opening are highly desirable in assessing this concept. This paper presents a numerical simulation of a ventral nozzle and compares the results with experimental data. Comparisons include visualizations of the flow along the ventral duct walls and in the tailpipe plane of symmetry. Performance calculations are also compared with measured values.

STOVL Hot Gas Ingestion Control Technology

A comprehensive wind tunnel test program was conducted to evaluate control of Hot Gas Ingestion (HGI) on a 9.2 percent scale model of the McDonnell Aircraft Company model 279-3C advanced Short Takeoff and Vertical Landing (STOVL) configuration. The test was conducted in the NASA-Lewis Research Center 9 ft by 15 ft Low Speed Wind Tunnel during the summer of 1987. Initial tests defined baseline HGI levels as determined by engine face temperature rise and temperature distortion. Subsequent testing was conducted to evaluate HGI control parametrically using Lift Improvement Devices (LIDs), forward nozzle splay angle, a combination of LIDs and forward nozzle splay angle, and main inlet blocking. The results from this test program demonstrate that HGI can be effectively controlled and that HGI is not a barrier to STOVL aircraft development.

A Technology Challenge

THE title of this report comes from the Keynote Address to the recent International Powered Lift Conference organised by the Royal Aeronautical Society. Attention at this gathering was focussed entirely on short take‐off and vertical landing (STOVL) technologiesf for fast jet combat aircraft. The strong international collaboration particularly between the USA and the UK has been a main feature of the evolution of these types. Seven areas of work have been outlined at the last conference of this nature and these largely remain the central themes. These are: plenum chamber burning; hot gas reingestion during VTOL manoevres; ground erosion; near field jet noise; powerplant controls; aircraft controls and flight/ powerplant controls integration; and airframes. It has been concluded that the most promising configuration for a future aircraft would include the two specific features of remote vertical lift in jet‐borne flight and conventional mixed flow propulsion for wing‐borne flight.

Multimission STOVL application of a hybrid powered-lift system

Short Takeoff and Vertical Landing (STOVL) aircraft are options for future replacement of sea-based Conventional Takeoff and Landing (CTOL) aircraft. A conceptual design study was conducted to evaluate the feasibility of a minimum-cost modification of the Lockheed S-3A airframe to an S-3 STOVL configuration. The STOVL concept is based on the use of four TF34 turbofan engines and the application of Lockheed's Advanced Internally Blown Jet Flap/Vectored Thrust (AIBF/VT) hybrid powered-lift system. The S-3 STOVL deck performance estimates are presented along with mission performance comparisons with four CTOL aircraft. These CTOL aircraft are the C-2A, E-2C, S-3A, and KA-6D for the Carrier On-board Delivery, Airborne Early Warning, Antisubmarine Warfare, and tanker missions respectively.

SEAKEEPING PERFORMANCE COMPARISON OF AIR CAPABLE SHIPS

ABSTRACTThe on‐going debate regarding the merits of large versus small aircraft carriers raises several issues concerning the ability of various ship configurations to support sea based air operations. One such issue is the question of the relative seakeeping performance of ship alternatives. In an effort to shed some light on the matter, a comparative seakeeping assessment of nine air capable ships covering a wide range of size and hull form was performed. An evaluation of the impact of aircraft and ship motion limitations on sea based air operations and a comparison of the relative ability of the ships to conduct air operations while in a seaway are presented. The specific air operations considered are launch, recovery, and support of aircraft. The ships evaluated are CVN‐71, CVA‐67 (MR), CVV, LHA‐1, VSS‐D, DDV‐2, DDV‐1D, DD‐963, and SWATH‐6. These ships have the combined capability to operate Vertical Takeoff and Landing (VTOL), Conventional Takeoff and Landing (CTOL), Short Takeoff and Arrested Landing (STOAL), and Short Takeoff and Vertical Landing (STOVL) type aircraft. Results indicate that seakeeping performance generally degrades with decreasing displacement, that SWATH‐6 performance is the least degraded, that elevator wetness can be an important degrader for ships with lower freeboards, that roll motion can be an important degrader for ships under 60,000 tons, and that percent time of operation is strongly dependent on the prevailing wave and wind environment.