Search Results

Since the entry of ultralight aircraft into the market in 1975, many changes have come about. With these changes, questions have arisen regarding the overall safety of these vehicles. This paper will show preliminary results of tests conducted to obtain an overall data base of a typical ultralight aircraft. These tests were conducted on an Airmass Sunburst Ultralight Model ‘C’ and include results from an experimental weight and balance as well as a theoretical drag analysis. The data base is viewed only as a starting point for allowing the ultralight industry to better understand the true characteristics exhibited by typical ultralight aircraft. This would allow for the design of safe ultralights under the current voluntary self-regulation program or any future programs that might be developed.

An economic analysis is presented of a composite (= staged) configuration option to a supersonic transport with transatlantic range. It is shown that the staged approach offers economic advantages over a conventional SST. A staged SST offers the possibility of ‘optimizing’ the configuration for the cruise flight condition, does not require flaps nor landing gear, does not carry any penalty for meeting FAR 36 takeoff and landing noise requirements and causes up to 30% less stratospheric pollution. Therefore, despite the potential for operational problems with launch and recovery, the staged SST option may have to be taken seriously.

The purpose of this paper is to describe an investigation of separate surface stability augmentation systems for general aviation aircraft. The program objectives were twofold: First a wind tunnel program to determine control effectiveness of separate surfaces in the presence of main surfaces, and hinge moment feedback from separate surfaces via the main surfaces to the pilot; second, a theoretical study to determine the minimum performance of actuators and sensors that can be tolerated, the best slaving gains to be used with separate surfaces, and control authority needed for proper operation under direct pilot control, under autopilot control, and in failure situations. On the basis of the results obtained, it has been concluded that separate surface systems are feasible and advantageous for use in general aviation aircraft.

A review is given of the NASA/Industry/University General Aviation Drag Reduction Workshop which was held at The University of Kansas, July 14-16, 1975. It is shown that large drag reductions can be made, particularly in propeller driven airplanes. It is also shown, however, that existing drag prediction methods are inadequate to cope with propeller driven airplanes. Many unknowns are shown to exist with regard to the problem of designing general aviation airplanes for minimum drag. Several areas for potentially fruitful research are indicated. A list of 123 drag references is included. This paper is based on work supported by NASA under NASA Grant NSG 1175.

A wind tunnel investigation was made of a new high-lift system consisting of a leading edge cusp flap combined with split upper and lower trailing edge flaps. The idea behind the system was to generate two strong spanwise vortices that would increase maximum lift and drag simultaneously. Test results were not encouraging. The spanwise vortices were observed, but were not sufficiently strong to generate the anticipated high lift. Several interesting flow phenomena were observed and are described. The purpose of this paper is to present a summary of results obtained from this wind tunnel test program.

Air travelers between medium sized coastal cities in the USA are faced with a major inconvenience: they are forced by existing airline schedules to make at least one stop in a major hub with a change of airplane and, sometimes even a change in air carrier. This inconvenience translates into lost time, missing of a connection due to delays and possible loss of luggage. These inconveniences could be alleviated if non-stop, coast-to-coast small jet commuters could be designed such that they can compete with the existing transcontinental transports on a DOC per passenger seat-mile basis. It is shown that significant advances in aerodynamic and propulsion design technology will be needed to enable the profitable development of such airplanes.

This paper describes work done under a NASA-Langley grant at the university of Kansas Flight Research Laboratory in the area of natural laminar flow and regional aircraft. The focus of this paper is on the application of natural laminar flow over various major wetted areas. In particular, efforts were concentrated on analyzing the potential benefits of achieving extensive laminar flow on the wing, empennage, and fuselage. The effect of the presence of large amounts of laminar flow is evaluated in terms of performance and efficiency improvement over an all-turbulent baseline aircraft. An introduction is given to the concept of regional aircraft, and the aerodynamic characteristics are compared to those of other airplane classes. Some recent aerodynamic developments are presented that justify, to a certain extent, the assumptions made concerning the amount of natural laminar flow that is possible for each surface.

This paper describes a simple, self-contained flight test data acquisition system. The system makes use of the latest sensor and microprocessor technology available, to reduce overall system costs. Coupled with this is the use of modern control theory techniques allowing minimization of data requirements, as well as flight time requirements. Capability of the system includes primarily stability and performance analysis of general aviation airplanes, although system versatility has been designed into the package. Presented are details of the prototype system constructed, as well as details of the data reduction technique utilized. Preliminary results of the flight test program have also been included which demonstrate the capability of this system.

The design and recovery considerations are presented for a staged supersonic transport (SSST). It is shown that the SSST offers economic benefits over the conventional SST. The SSST benefits from the ability to “optimize” the design for minimum drag during supersonic cruise without the penalties of: landing gear, extensive flaps for landing, and the meeting of FAR 36 noise requirements. The recovery considerations are also presented to validate the SSST concept.

A user-friendly method for analyzing longitudinal and lateral-directional trim problems for airplanes with all engines operating (AEO) and with one engine inoperative (OEI) is presented. The method allows for rapid evaluation of various critical handling qiality parameters, such as stick-force per ‘g’ and stick-force versus speed gradients. In addtion, the effect of failures in trim systems on cockpit control forces and on control surface and/or tab deflections can be assessed. Also, the method can be used for sizing of tab control systems, down-springs, bob-weights and interconnect springs. Finally, elevator hingemoment derivatives for rather arbitrary aerodynamic balance configurations can be quickly estimated.