Aeronautical fuel conservation possibilities for advanced subsonic transports

The anticipated growth of air transportation is in danger of being constrained by increased prices and insecure sources of petroleum-based fuel. Fuel-conservation possibilities attainable through the application of advances in aeronautical technology to aircraft design are identified with the intent of stimulating NASA R and T and systems-study activities in the various disciplinary areas. The material includes drag reduction; weight reduction; increased efficiency of main and auxiliary power systems; unconventional air transport of cargo; and operational changes

Circulation control propellers for general aviation, including a BASIC computer program

The feasibility of replacing variable pitch propeller mechanisms with circulation control (Coanada effect) propellers on general aviation airplanes was examined. The study used a specially developed computer program written in BASIC which could compare the aerodynamic performance of circulation control propellers with conventional propellers. The comparison of aerodynamic performance for circulation control, fixed pitch and variable pitch propellers is based upon the requirements for a 1600 kg (3600 lb) single engine general aviation aircraft. A circulation control propeller using a supercritical airfoil was shown feasible over a representative range of design conditions. At a design condition for high speed cruise, all three types of propellers showed approximately the same performance. At low speed, the performance of the circulation control propeller exceeded the performance for a fixed pitch propeller, but did not match the performance available from a variable pitch propeller. It appears feasible to consider circulation control propellers for single engine aircraft or multiengine aircraft which have their propellers on a common axis (tractor pusher). The economics of the replacement requires a study for each specific airplane application

Aerodynamic evaluation of circulation control propellers

The aerodynamic compatibility of fixed-pitch circulation-control (CC) propellers with the performance characteristics and requirements of a 1600 kg (3600 lb) single-engine variable-pitch propeller general aviation airplane was evaluated. The initial results with elliptical-shaped CC airfoils indicated that the feasibility of application to fixed-pitch propellers was doubtful for the class of airplane investigated (cruise speed of about 300 km/hr) and improbable for higher-speed airplanes. Supplemental data for a cambered circulation-control supercritical airfoil, which became available after completion of the initial evaluation, were subsequently analyzed and are included in the Addendum to this report. With the much superior aerodynamic characteristics of the CC-supercritical airfoil, elimination of variable pitch appears aerodynamically feasible for low-speed airplanes through the use of a moderate amount of upper-surface blowing near the trailing edge during cruise. Overall feasibility depends upon results of structural and systems-type analyses

Experimental Study of the Effects of Finite Surface Disturbances and Angle of Attack on the Laminar Boundary Layer of an NACA 64A010 Airfoil with Area Suction

A Langley low-turbulence wind-tunnel investigation of a porous NACA 64A010 airfoil section has been made to determine the effectiveness of area suction in maintaining full-chord laminar flow behind finite disturbances and at angles of attacks other than 0 degrees. Aero suction resulted in only a small increase in the size of a finite disturbance required to cause premature boundary-layer transition as compared with that for the airfoil without suction. Combined wake and suction drags lower than the drag of the plain airfoil were obtained through a range of low lift coefficient by the use of area suction

A Guide for participatory mapping of ecosystem services in multiuse agricultural landscapes: How to conduct a rapid spatial assessment of ecosystem services

This guide presents a step-by-step approach in using a participatory mapping method with community members to rapidly identify and map ecosystem services and changes in their supply across multiuse agricultural landscapes. Nongovernmental organizations (NGOs), government agencies and researchers can use this approach to learn from communities about how they use and access natural resources. This activity uses a landscape approach to help land management practitioners understand the ways in which people depend on and access ecosystem services and how changes in their availability impact livelihoods across the landscape. The mapping exercise involves using free, high resolution satellite imagery from Google Earth Pro, which presents an aerial view of the community in fine detail. Participants from the community in question identify key features on the map, which help them to understand the extent of the area the map represents. They are then led through a discussion on their resources such as water, livestock, cultivated land and uncultivated land. Through the discussion participants identify: (1) where resources are located on the landscape and how they are used; (2) changes in the supply of resources and how these changes are impacting livelihoods; and (3) restrictions to access, conflicts over use and management of each resource in question. Mapping with different groups, such as men, women and youth can show which resources are most important to different groups as well as differences in access and perceptions of change. The mapping exercise is intended to take between two and a half and three hours: including introductory and concluding discussions can add on another two hours. This guide presents examples and tips from mapping exercises that tested this approach in Ghana, Kenya, Malawi and Tanzania. We outline how this mapping exercise could be used in research, development and planning. Additionally, this guide includes appendices that contain: (1) a detailed explanation of how to create maps for each activity; (2) a set of materials that have been developed to accompany the mapping exercise; (3) steps for digitizing the maps (4) case study examples; and (5) additional sources of information

Laminar-flow flight experiments

The flight testing conducted over the past 10 years in the NASA laminar-flow control (LFC) will be reviewed. The LFC program was directed towards the most challenging technology application, the high supersonic speed transport. To place these recent experiences in perspective, earlier important flight tests will first be reviewed to recall the lessons learned at that time