NASA lift fan V/STOL transport technology status.
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Deckert, W. H.↗
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Effect of rotor design tip speed on aerodynamic performance of a model VTOL lift fan under static and crossflow conditions.
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Stockman, N. O.↗
Mechanically coupled lift fan propulsion and control for multimission V/STOL aircraft
A two-engine, three-fan V/STOL airplane was designed to fulfill naval operational missions. Use of interconnected variable pitch fans led to a good balance between the requirements for high thrust and responsive control at low speed, and efficient thrust at cruise speeds. Engine-out requirements, integration of propulsion and aerodynamic controls, and the propulsion installation were the major factors influencing the configuration. An airplane with a multimission capability from both vertical and short takeoff was conceived.
Zabinsky, J. M.↗
Simulating study of the interaction between the propulsion and flight control systems of a subsonic lift fan VTOL
The possibility of interactions between the propulsion and flight control systems of a three-fan subsonic VTOL aircraft was studied using nonreal time simulation. Time histories of critical internal engine parameters were obtained and possible deleterious effects of engine dynamics on flight control were identified and analyzed. No deleterious effects, with the exception of the effects of the fan actuator deadband, were found. A method of alleviating these effects through feedback of the actuator output to the flight controller was developed.
Tinling, B. E.↗
Summary of Lift and Lift/Cruise Fan Powered Lift Concept Technology
A summary is presented of some of the lift and lift/cruise fan technology including fan performance, fan stall, ground effects, ingestion and thrust loss, design tradeoffs and integration, control effectiveness and several other areas related to vertical short takeoff and landing (V/STOL) aircraft conceptual design. The various subjects addressed, while not necessarily pertinent to specific short takeoff/vertical landing (STOVL) supersonic designs being considered, are of interest to the general field of lift and lift/cruise fan aircraft designs and may be of importance in the future. The various wind tunnel and static tests reviewed are: (1) the Doak VZ-4 ducted fan, (2) the 0.57 scale model of the Bell X-22 ducted fan aircraft, (3) the Avrocar, (4) the General Electric lift/cruise fan, (5) the vertical short takeoff and landing (V/STOL) lift engine configurations related to ingestion and consequent thrust loss, (6) the XV-5 and other fan-in-wing stall consideration, (7) hybrid configurations such as lift fan and lift/cruise fan or engines, and (8) the various conceptual design studies by air-frame contractors. Other design integration problems related to small and large V/STOL transport aircraft are summarized including lessons learned during more recent conceptual design studies related to a small executive V/STOL transport aircraft.
Cook, Woodrow L.↗
Aerodynamic characteristics of a V/STOL TRANSPORT model with lift and lift-cruise fan power plants
The aerodynamic characteristics of lift fans mounted ahead of the wing, rotating cruise fans, and tandem mounted lift fans faired into the wing have been studied. The tests results indicated that the complete configurations, that is, the lift-cruise fan and tandem lift fan configurations, had generally acceptable aerodynamic characteristics. The positive induced lift due to fan flow interference with the airplane flow field was a small percentage of the installed thrust but was adequate to provide significant increases in payload with STOL operation.
JET TRANSPORT↗
Wind-tunnel investigation of a large-scale model of a lift-cruise fan V/STOL aircraft with extended lift-cruise nacelles
The aerodynamic characteristics of a large-scale model of a lift/cruise fan V/STOL aircraft were determined. The model was equipped with three fans, one mounted in the forward section of the fuselage in a lift mode, and two mounted on top of the wing adjacent to the fuselage in a lift/cruise mode. The data that were obtained include longitudinal and lateral-directional characteristics of the model, with the horizontal tail on and off, for both the powered-lift and cruise configurations. Lateral-directional characteristics were obtained with the horizontal and vertical tail sections removed. Powered-lift data were obtained at several wind-tunnel velocities and at several lift-cruise fan thrust vector angles by varying the position of the hooded deflectors from 0 deg (the cruise condition) to 90 deg.
Gambucci, B. J.↗
Rene 95 brazed joint metallurgical program
This metallurgical program was specifically conducted for the establishment of material properties required for the design of the LF460 fan. The LF460 lift fan is an advanced 18:1 high thrust to weight single stage design. It has a turbine attached to the outer flowpath of the fan blade tip which minimizes the axial depth of the fan. Advanced lightweight attachment designs are employed in this concept to achieve minimum mass polar moments of inertia which are required for good aircraft flight response control. The design features which are unique to this advanced LF460 lift fan are the 0.010 inch thin Udimet 700 alloy integral tip turbine design, minimum weight braze attachment of the turbine to the fan blade, and the high strength and elevated temperature capability of the Rene'95 alloy for the fan blade. The data presented in this report show that the LF460 fan rotor design is feasible and that the design stresses and margins of safety were more than adequate. Prior to any production application, however, additional stress rupture/shear lap joints should be run in order to establish a firm 1200 F stress rupture curve for the CM50 braze metal.
Gay, C.↗
Rationale for selection of a flight control system for lift cruise fan V/STOL aircraft
Various features of the lift cruise fan V/STOL concept are briefly reviewed. The ability to operate from small ships in adverse weather, low visibility, and rough sea conditions is emphasized as is the need for a highly capable, flexible, and reliabile flight control system. A three channel control by wire, digital flight control system is suggested. The requirement for automatic flight control, the advantage of control by wire implementation, the preference for a digital computer, and the need for three channel redundancy are among the factors discussed.
Konsewicz, R. K.↗
Aerodynamic characteristics of a large-scale V/STOL transport model with lift and lift-cruise fans
Aerodynamic characteristics of V/STOL transport model powered by lift and rotating cruise fans
V/STOL AIRCRAFT↗
Lift cruise fan V/STOL aircraft conceptual design study T-39 modification. Volume 1: Technical report
The conversion of two T-39 aircraft into lift cruise fan research and technology vehicles is discussed. The concept is based upon modifying the T-39A (NA265-40) Sabreliner airframe into a V/STOL configuration by incorporating two LCF-459 lift cruise fans and three YJ-97 gas generators. The propulsion concept provides the thrust for horizontal flight or lift for vertical flight by deflection of bifurcated nozzles while maintaining engine out safety throughout the flight envelope. The configuration meets all the study requirements specified for the design with control powers in VTOL and conversion in excess of the requirement making it an excellent vehicle for research and development. The study report consists of two volumes; Volume 1 (Reference a) contains background data detailed description and technical substantiation of the aircraft. Volume 2 includes cost data, scheduling and program planning not addressed in Volume 1.
Elliott, D. W.↗
Low speed wind tunnel test of ground proximity and deck edge effects on a lift cruise fan V/STOL configuration, volume 1
The characteristics were determined of a lift cruise fan V/STOL multi-mission configuration in the near proximity to the edge of a small flat surface representation of a ship deck. Tests were conducted at both static and forward speed test conditions. The model (0.12 scale) tested was a four fan configuration with modifications to represent a three fan configuration. Analysis of data showed that the deck edge effects were in general less critical in terms of differences from free air than a full deck (in ground effect) configuration. The one exception to this was when the aft edge of the deck was located under the center of gravity. This condition, representative of an approach from the rear, showed a significant lift loss. Induced moments were generally small compared to the single axis control power requirements, but will likely add to the pilot work load.
Stewart, V. R.↗
Simulation test results for lift/cruise fan research and technology aircraft
A flight simulation program was conducted on the flight simulator for advanced aircraft (FSAA). The flight simulation was a part of a contracted effort to provide a lift/cruise fan V/STOL aircraft mathematical model for flight simulation. The simulated aircraft is a configuration of the Lift/Cruise Fan V/STOL research technology aircraft (RTA). The aircraft was powered by three gas generators driving three fans. One lift fan was installed in the nose of the aircraft, and two lift/cruise fans at the wing root. The thrust of these fans was modulated to provide pitch and roll control, and vectored to provide yaw, side force control, and longitudinal translation. Two versions of the RTA were defined. One was powered by the GE J97/LF460 propulsion system which was gas-coupled for power transfer between fans for control. The other version was powered by DDA XT701 gas generators driving 62 inch variable pitch fans. The flight control system in both versions of the RTA was the same.
Bland, M. P.↗
V/STOL systems research aircraft: A tool for cockpit integration
The next generation ASTOVL aircraft will have a complicated propulsion system. The configuration choices include Direct Lift, Lift-Fan and Lift + Lift/Cruise but the aircraft must also have supersonic performance and low-observable characteristics. The propulsion system may have features such as flow blockers, vectoring nozzles and flow transfer schemes. The flight control system will necessarily fully integrate the aerodynamic surfaces and the propulsive elements. With a fully integrated, fly-by-wire flight/propulsion control system, the options for cockpit integration are interesting and varied. It is possible to de-couple longitudinal and vertical responses allowing the pilot to close the loop on flightpath and flightpath acceleration directly. In the hover, the pilot can control the translational rate directly without having to stabilize the inner rate and attitude loops. The benefit of this approach, reduced workload and increased precision, has previously been demonstrated through several motion-based simulations. In order to prove the results in flight, the V/STOL System Research Aircraft (VSRA) was developed at the NASA Ames Research Center. The VSRA is the YAV-8B Prototype modified with a research flight control system using a series-parallel servo configuration in all the longitudinal degrees of freedom (including thrust and thrust vector angle) to provide an integrated flight and propulsion control system in a limited envelope. Development of the system has been completed and flight evaluations of the response types have been performed. In this paper we will discuss the development of the VSRA, the evolution of the flightpath command and translational rate command response types and the Guest Pilot evaluations of the system. Pilot evaluation results are used to draw conclusions regarding the suitability of the system to satisfy V/STOL requirements.
Stortz, Michael W.↗
V/STOL Systems Research Aircraft: A Tool for Cockpit Integration
The next generation ASTOVL aircraft will have a complicated propulsion System. The configuration choices include Direct Lift, Lift-Fan and Lift+Lift /Cruise but the aircraft must also have supersonic performance and low-observable characteristics. The propulsion system may have features such as flow blockers, vectoring nozzles and flow transfer schemes. The flight control system will necessarily fully integrate the aerodynamic surfaces and the propulsive elements. With a fully integrated, fly-by-wire flight/propulsion control system, the options for cockpit integration are interesting and varied. It is possible to decouple longitudinal and vertical responses allowing the pilot to close the loop on flight path and flight path acceleration directly. In the hover, the pilot can control the translational rate directly without having to stabilize the inner rate and attitude loops. The benefit of this approach, reduced workload and increased precision. has previously been demonstrated through several motion-based simulations. In order to prove the results in flight, the V/STOL System Research Aircraft (VSRA) was developed at the NASA Ames Research Center. The VSRA is the YAV-8B Prototype modified with a research flight control system using a series-parallel servo configuration in all the longitudinal degrees of freedom (including thrust and thrust vector angle) to provide an integrated flight and propulsion control system in a limited envelope. Development of the system has been completed and flight evaluations of the response types have been performed. In this paper we will discuss the development of the VSRA, the evolution of the flight path command and translational rate command response types and the Guest Pilot evaluations of the system. Pilot evaluation results will be used to draw conclusions regarding the suitability of the system to satisfy V/STOL requirements.
Stortz, Michael W.↗
Variable pitch fan system for NASA/Navy research and technology aircraft
Preliminary design of a shaft driven, variable-pitch lift fan and lift-cruise fan was conducted for a V/STOL Research and Technology Aircraft. The lift fan and lift-cruise fan employed a common rotor of 157.5 cm diameter, 1.18 pressure ratio variable-pitch fan designed to operate at a rotor-tip speed of 284 mps. Fan performance maps were prepared and detailed aerodynamic characteristics were established. Cost/weight/risk trade studies were conducted for the blade and fan case. Structural sizing was conducted for major components and weights determined for both the lift and lift-cruise fans.
Ryan, W. P.↗
Applications of advanced V/STOL aircraft concepts to civil utility missions, volume 1
The suitability of advanced V/STOL aircraft to civil utility applications was assessed for offshore oil support, forest fire support, transport, and humanitarian missions. The aircraft concepts considered were a lift fan aircraft, a tilt rotor aircraft, and an advanced helicopter. All the aircraft had a design payload of 2,268 kg. (5,000 lb.) with the maximum range varying from 2,224 km. (1,800 nm) for the lift fan STOL to 1,482 km (800 nm) for the advanced helicopter. The analysis of these missions considered such factors as aircraft performance, annual utilization, initial cost, and operating cost. It is concluded that all the advanced V/STOL aircraft concepts generally performed these missions better than contemporary aircraft. The lift fan aircraft and the tilt rotor aircraft were found to be effective for the offshore oil and the forest fire support missions. The lift fan aircraft in the VTOL mode was also found to be very attractive for the executive transport mission where the passenger time value was $30/hr. or more.
Source record↗
V/STOL gets a lift
The concept of a supersonic STOVL that could offer enhanced mission capability, survivability, operational flexibility, and utility over conventional aircraft is presented. Emphasis is currently on design studies, CFD work, small- and large-scale wind tunnel tests, simulation activities, flight experiments, and ground environment experiments. Propulsion system technology centers about the adaptation of existing or off-the-shelf engines. Concepts under study include separate flow in hover, gas-driven lift fan, and shaft-driven lift fan. NASA is examining generic valve and ducting configurations with airflow at ambient temperature and at temperatures up to 1000 F to gather pressure loss and heat transfer data. Advanced civil rotorcraft technologies examined include high-efficiency/dual-mode components such as torque converters; lightweight, quiet transmissions; and variable geometry power turbines; along with dual-function or convertible engines.
Biesiadny, Tom↗