Safety considerations for powered-lift STOL aircraft
Safety characteristics for powered lift of commerical STOL aircraft
Holzhauser, C. A.↗
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A Flight Evaluation of a VTOL Jet Transport Under Visual and Simulated Instrument Conditions
Transition, approach, and vertical landing tests for VTOL transport in terminal area
Holzhauser, C. A.↗
A flight evaluation of VTOL jet transport under visual and simulated instrument conditions
A flight investigation was performed with the Dornier DO-31 VTOL to evaluate the performance, handling qualities, and operating characteristics that are considered to be important in the operation of a commerical VTOL transport in the terminal area. The DO-31, a 20,000 kilogram transport, has a mixed jet propulsion system; main engines with nozzles deflect from a cruise to a hover position, and vertical lift engines operated below 170 knots. This VTOL mode incorporates pitch and roll attitude and yaw rate stabilization. The tests concentrated on the transition, approach, and vertical landing. The mixed jet propulsion system provided a large usable performance envelope that enabled simulated IFR approaches to be made on 7 deg and 12 deg glide slopes. In these approaches management of thrust magnitude and direction was a primary problem, and some form of integrating the controls will be necessary. The handling qualities evaluation pointed out the need for additional research of define flight path criteria. The aircraft had satisfactory control and stability in hover out of ground effect. The recirculation effects in vertical landing were large below 15 meters.
Holzhauser, C. A.↗
Pitch attitude, flight path, and airspeed control during approach and landing of a powered lift STOL aircraft
Analytical investigations and piloted moving base simulator evaluations were conducted for manual control of pitch attitude, flight path, and airspeed for the approach and landing of a powered lift jet STOL aircraft. Flight path and speed response characteristics were described analytically and were evaluated for the simulation experiments which were carried out on a large motion simulator. The response characteristics were selected and evaluated for a specified path and speed control technique. These charcteristics were: (1) the initial pitch response and steady pitch rate sensitivity for control of attitude with a pitch rate command/ attitude hold system, (2) the initial flight path response, flight path overshoot, and flight path-airspeed coupling in response to a change in thrust, and (3) the sensitivity of airspeed to pitch attitude changes. Results are presented in the form of pilot opinion ratings and commentary, substantiated where appropriate by response time histories and aircraft states at the point of touchdown.
Franklin, J. A.↗
Flight-path and airspeed control for the STOL approach and landing
Analytical investigations and piloted moving base simulator evaluations were conducted for manual control of flight path and airspeed for the approach and landing of a powered lift jet STOL aircraft. Flight-path and airspeed response characteristics were described analytically and were evaluated for the simulation experiments which were carried out on a large motion simulator. The response characteristics were selected and evaluated for a specified path and speed control technique. These characteristics were the initial flight-path response, flight-path overshoot, flight-path-airspeed coupling in response to a change in thrust, and the sensitivity of airspeed to pitch-attitude changes. Results are presented in the form of pilot opinion ratings and commentary, substantiated where appropriate by response time histories and aircraft states at the point of touchdown.
Franklin, J. A.↗
Comparisons of simulator and flight results on augmentor-wing jet STOL research aircraft
The considerations involved in making a piloted simulator an effective research tool in the design and development of new aircraft are discussed. An assessment of the limitations of the simulator in depicting real flight as well as the problem of recognizing erroneous results when the simulator is supplied with incorrect input data is made. Examples of the ways in which the simulator is used to design and develop the augmentor-wing aircraft are presented. Four areas of investigation are: (1) to design the lateral control system for proper feel and response, (2) determine the effect of engine failure during approach, (3) develop the best technique for controlling flight path during approach, and (4) the significance of lift loss in ground effect and how to compensate for such loss.
Innis, R. C.↗
A flight study of the use of direct-lift-control flaps to improve station keeping during in-flight refueling
To investigate the effectiveness of fast-acting flaps as direct-lift-control (DLC) devices on a fighter airplane, the aileron servo systems of an F-100C variable-stability airplane were modified to provide symmetrical actuation of the surfaces. Initial flight tests using DLC indicated that the task of formation flying and, hence, in-flight refueling could be eased by actuating the DLC flaps through the conventional control stick, with the degree of improvement depending on the basic stability of the receiver aircraft. Results of refueling approaches and connections with U.S. Air Force tankers indicated a moderate overall improvement in vertical station-keeping performance (approximately 19 percent) and a sizeable overall decrease in receiver airplane motions and control activity (approximately 40 percent) with DLC.
Mcneill, W. E.↗
Takeoff and landing performance and noise measurements of a deflected slipstream STOL airplane with interconnected propellers and rotating cylinder flaps
A YOV-10A aircraft was modified to incorporate rotating cylinder flaps and interconnected propellers with Lycoming T-53-L11 engines. Flight tests were made to evaluate the low speed handling qualities and performance characteristics. The flight test results indicated that landings could be made with approach speeds of 55 to 65 knots (CL = 4.5) and descent angles of 6 deg to 8 deg for total flap angles of 60 deg to 75 deg. At higher flap angles, deterioration of stability and control characteristics precluded attempts at landing. The noise level on the ground under an 8 deg landing approach path was below 86 PNdB at distances beyond 1 nautical mile from touchdown. Takeoffs were made with 30 deg to 45 deg flaps at lift off speeds of 75 to 80 knots and climb angles of 4 deg to 8 deg. Noise levels were below 83 PNdB at 3.5 nautical miles from the start of ground roll.
Weiberg, J. A.↗
A Flight Investigation of the STOL Characteristics of an Augmented Jet Flap STOL Research Aircraft
The flight test program objectives are: (1) To determine the in-flight aerodynamic, performance, and handling qualities of a jet STOL aircraft incorporating the augmented jet flap concept; (2) to compare the results obtained in flight with characteristics predicted from wind tunnel and simulator test results; (3) to contribute to the development of criteria for design and operation of jet STOL transport aircraft; and (4) to provide a jet STOL transport aircraft for STOL systems research and development. Results obtained during the first 8 months of proof-of-concept flight testing of the aircraft in STOL configurations are reported. Included are a brief description of the aircraft, fan-jet engines, and systems; a discussion of the aerodynamic, stability and control, and STOL performance; and pilot opinion of the handling qualities and operational characteristics.
Quigley, H. C.↗
Flight-path and airspeed control during landing approach for powered-lift aircraft
Manual control of flight path and airspeed during landing approach has been investigated for powered-lift transport aircraft. An analysis was conducted to identify the behavior of the aircraft which would be potentially significant to the pilot controlling flight path and airspeed during the approach. The response characteristics found to describe the aircraft behavior were (1) the initial flight-path response and flight-path overshoot for a step change in thrust, (2) the steady-state coupling of flight path and airspeed for a step change in thrust, and (3) the sensitivity of airspeed to changes in pitch attitude. The significance of these response characteristics was evaluated by pilots on a large-motion, ground-based simulator at Ames Research Center. Coupling between flight path and airspeed was considered by the pilot to be the dominant influence on handling qualities for the approach task. Results are compared with data obtained from flight tests of three existing powered-lift V/STOL aircraft.
Franklin, J. A.↗
Operating problems of V/STOL aircraft in STOL-type landing and approach
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Innis, R. C.↗
Operational experience with a powered-lift STOL aircraft
The experience gained in over four years of STOL operations with the augmentor wing research aircraft and the background of operation of other STOL powered-lift aircraft indicate that the use and percent of lift achieved by powered lift have significant effects on the operational characteristics of STOL aircraft and, therefore, on the performance that can be achieved. A brief description of the augmentor wing including the means by which it achieves its powered lift is presented. Specific problem areas relating to the control of longitudinal flight path are discussed as well as the consequences these might have on the design and operation of this class of aircraft. Particular emphasis is given to the approach and landing phase of flight where the consequences of the powered lift are most pronounced, and the resultant characteristics most different from those of conventional aircraft.
Innis, R. C.↗
Flight evaluation of advanced flight control systems and cockpit displays for powered-lift STOL Aircraft
A flight research program was conducted to assess the improvements, in longitudinal path control during a STOL approach and landing, that can be achieved with manual and automatic control system concepts and cockpit displays with various degrees of complexity. NASA-Ames powered-lift Augmentor Wing Research Aircraft was used in the research program. Satisfactory flying qualities were demonstrated for selected stabilization and command augmentation systems and flight director combinations. The ability of the pilot to perform precise landings at low touchdown sink rates with a gentle flare maneuver was also achieved. The path-control improvement is considered to be applicable to other powered-lift aircraft configurations.
Franklin, J. A.↗
Longitudinal handling qualities during approach and landing of a powered lift STOL aircraft
Longitudinal handling qualities evaluations were conducted on the Ames Research Center Flight Simulator for Advanced Aircraft (FSAA) for the approach and landing tasks of a powered lift STOL research aircraft. The test vehicle was a C-8A aircraft modified with a new wing incorporating internal blowing over an augmentor flap. The investigation included: (1) use of various flight path and airspeed control techniques for the basic vehicle; (2) assessment of stability and command augmentation schemes for pitch attitude and airspeed control; (3) determination of the influence of longitudinal and vertical force coupling for the power control; (4) determination of the influence of pitch axis coupling with the thrust vector control; and (5) evaluations of the contribution of stability and command augmentation to recovery from a single engine failure. Results are presented in the form of pilot ratings and commentary substantiated by landing approach time histories.
Franklin, J. A.↗
Flight evaluation of flight-path control required for the approach and landing of STOL aircraft
Flight experiments have been conducted as part of a program to assess requirements for flight-path control for glide-slope tracking and for control of the flare and landing for STOL aircraft. The Augmentor Wing Research Aircraft was used to perform landing approaches on a 7.5 deg glide slope to landings on a 30 x 518 m STOL runway. The flight results identified flight-path overshoot and vertical velocity damping to be the dominant aircraft response characteristics that affect glide-slope tracking. The one prominent contribution to control of flare using pitch attitude was the short-term path response.
Franklin, J. A.↗
A flight investigation of the stability, control, and handling qualities of an augmented jet flap STOL airplane
The stability, control, and handling qualities of an augmented jet flap STOL airplane are presented. The airplane is an extensively modified de Havilland Buffalo military transport. The modified airplane has two fan-jet engines which provide vectorable thrust and compressed air for the augmentor jet flap and Boundary-Layer Control (BLC). The augmentor and BLC air is cross ducted to minimize asymmetric moments produced when one engine is inoperative. The modifications incorporated in the airplane include a Stability Augmentation System (SAS), a powered elevator, and a powered lateral control system. The test gross weight of the airplane was between 165,000 and 209,000 N (37,000 and 47,000 lb). Stability, control, and handling qualities are presented for the airspeed range of 40 to 180 knots. The lateral-directional handling qualities are considered satisfactory for the normal operating range of 65 to 160 knots airspeed when the SAS is functioning. With the SAS inoperative, poor turn coordination and spiral instability are primary deficiencies contributing to marginal handling qualities in the landing approach. The powered elevator control system enhanced the controllability in pitch, particularly in the landing flare and stall recovery.
Vomaske, R. F.↗
Flight evaluation of configuration management system concepts during transition to the landing approach for a powered-lift STOL aircraft
Flight experiments were conducted to evaluate two control concepts for configuration management during the transition to landing approach for a powered-lift STOL aircraft. NASA Ames' augmentor wing research aircraft was used in the program. Transitions from nominal level-flight configurations at terminal area pattern speeds were conducted along straight and curved descending flightpaths. Stabilization and command augmentation for attitude and airspeed control were used in conjunction with a three-cue flight director that presented commands for pitch, roll, and throttle controls. A prototype microwave system provided landing guidance. Results of these flight experiments indicate that these configuration management concepts permit the successful performance of transitions and approaches along curved paths by powered-lift STOL aircraft. Flight director guidance was essential to accomplish the task.
Franklin, J. A.↗
Flight evaluation of stabilization and command augmentation system concepts and cockpit displays during approach and landing of powered-lift STOL aircraft
A flight research program was conducted to assess the effectiveness of manual control concepts and various cockpit displays in improving altitude (pitch, roll, and yaw) and longitudinal path control during short takeoff aircraft approaches and landings. Satisfactory flying qualities were demonstrared to minimum decision heights of 30 m (100 ft) for selected stabilization and command augmentation systems and flight director combinations. Precise landings at low touchdown sink rates were achieved with a gentle flare maneuver.
Franklin, J. A.↗