Design Drivers of Energy-Efficient Transport Aircraft

The fuel energy consumption of subsonic air transportation is examined. The focus is on identification and quantification of fundamental engineering design tradeoffs which drive the design of subsonic tube and wing transport aircraft. The sensitivities of energy efficiency to recent and forecast technology developments are also examined

Aerodynamics of heat exchangers for high-altitude aircraft

Reduction of convective beat transfer with altitude dictates unusually large beat exchangers for piston- engined high-altitude aircraft The relatively large aircraft drag fraction associated with cooling at high altitudes makes the efficient design of the entire heat exchanger installation an essential part of the aircraft's aerodynamic design. The parameters that directly influence cooling drag are developed in the context of high-altitude flight Candidate wing airfoils that incorporate heat exchangers are examined. Such integrated wing-airfoil/heat-exchanger installations appear to be attractive alternatives to isolated heat.exchanger installations. Examples are drawn from integrated installations on existing or planned high-altitude aircraft

Development and testing of airfoils for high-altitude aircraft

Specific tasks included airfoil design; study of airfoil constraints on pullout maneuver; selection of tail airfoils; examination of wing twist; test section instrumentation and layout; and integrated airfoil/heat-exchanger tests. In the course of designing the airfoil, specifically for the APEX test vehicle, extensive studies were made over the Mach and Reynolds number ranges of interest. It is intended to be representative of airfoils required for lightweight aircraft operating at extreme altitudes, which is the primary research objective of the APEX program. Also considered were thickness, pitching moment, and off-design behavior. The maximum ceiling parameter M(exp 2)C(sub L) value achievable by the Apex-16 airfoil was found to be a strong constraint on the pullout maneuver. The NACA 1410 and 2410 airfoils (inverted) were identified as good candidates for the tail, with predictable behavior at low Reynolds numbers and good tolerance to flap deflections. With regards to wing twist, it was decided that a simple flat wing was a reasonable compromise. The test section instrumentation consisted of surface pressure taps, wake rakes, surface-mounted microphones, and skin-friction gauges. Also, a modest wind tunnel test was performed for an integrated airfoil/heat-exchanger configuration, which is currently on Aurora's 'Theseus' aircraft. Although not directly related to the APEX tests, the aerodynamics or heat exchangers has been identified as a crucial aspect of designing high-altitude aircraft and hence is relevant to the ERAST program

Modeling of heavy-gas effects on airfoil flows

Thermodynamic models were constructed for a calorically imperfect gas and for a non-ideal gas. These were incorporated into a quasi one dimensional flow solver to develop an understanding of the differences in flow behavior between the new models and the perfect gas model. The models were also incorporated into a two dimensional flow solver to investigate their effects on transonic airfoil flows. Specifically, the calculations simulated airfoil testing in a proposed high Reynolds number heavy gas test facility. The results indicate that the non-idealities caused significant differences in the flow field, but that matching of an appropriate non-dimensional parameter led to flows similar to those in air

Method for Simultaneous Wing Aerodynamic and Structural Load Prediction

A calculation method is presented for the simultaneous solution of aerodynamic and structural loads on arbitrary high aspect ratio wings. The wing aerodynamics are modeled using lifting line theory with roll rate, yaw, and yaw rate effects included. The wing structure is modeled as a nonlinear beam with vertical and horizontal displacement and torsional degrees of freedom. Axial compression effects are also incorporated to permit modeling of wings with external bracing struts or wires. The aerodynamic and structural problems together constitute a coupled nonlinear system for the aerodynamic and structural unknowns, which is discretized anci solved using a global Newton method. The overall procedure permits computationally economical prediction of: 1. Aerodynamic and structural loads for a very wide range of operating conditions. 2. Induced drag with static wing twist effects included. 3. Lateral and longitudinal wing static stability derivatives and roll-yaw coupling forces incorporating wing deflections. 4. Static divergence and aileron reversal speeds. Buckling loads for externally braced wings. Examples are drawn from the wing design of the Daedalus human powered aircraft. Nomenclature Coordinates and dimensions wingspan local wing chord spanwise node index and maximum index chordwise shear center location Cartesian coordinates fixed to aircraft local coordinates fixed to wing section s location of strut or wire attach point spanwise Glauert coordinate angle of external bracing wire local angle of attack (no loads

Advanced Configurations for Very Large Subsonic Transport Airplanes

Recent aerospace industry interest in developing a subsonic commercial transport airplane with 50 percent greater passenger capacity than the largest existing aircraft in this category (the Boeing 747-400 with approximately 400-450 seats) has generated a range of proposals based largely on the configuration paradigm established nearly 50 years ago with the Boeing B-47 bomber. While this basic configuration paradigm has come to dominate subsonic commercial airplane development since the advent of the Boeing 707/Douglas DC-8 in the mid-1950's, its extrapolation to the size required to carry more than 600-700 passengers raises several questions. To explore these and a number of related issues, a team of Boeing, university, and NASA engineers was formed under the auspices of the NASA Advanced Concepts Program. The results of a Research Analysis focused on a large, unconventional transport airplane configuration for which Boeing has applied for a patent are the subject of this report. It should be noted here that this study has been conducted independently of the Boeing New Large Airplane (NLA) program, and with the exception of some generic analysis tools which may be common to this effort and the NLA (as will be described later), no explicit Boeing NLA data other than that published in the open literature has been used in the conduct of the study reported here

A new transformation and integration scheme for the compressible boundary layer equations, and solution behavior at separation

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1983.MICROFICHE COPY AVAILABLE IN ARCHIVES AND AEROIncludes bibliographical references.by Mark Drela.M.S

Two-dimensional transonic aerodynamic design and analysis using the Euler equations

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND AEROBibliography: leaves 139-143.by Mark Drela.Ph.D

A Calculation Method For The Three-Dimensional Boundary-Layer Equations In Integral Form

A new numerical method is developed to solve the threedimensional boundary-layer equations, in integral form, on non-orthogonal grids. The finite-volume scheme employed eliminates the need to compute metric-gradient terms found in curvilinear-coordinate finite-difference methods. The integral method is based on two equations for momentum and one for kinetic energy with empirical equilibrium compressible turbulent-flow closure relations selectively extracted from the literature. Johnston's model is used for the crossflow. The non-linear discrete equations are solved simultaneously using the Newton-Raphson method along a row of cells and the solution is marched successively downstream. Along each row, cell residuals are distributed to nodes in a manner consistent with the local direction of characteristic lines. Results are computed for a well-known infinite swept wing case to evaluate empirical-closure accuracy, and for a finite swept wing case to demonstrate the full threedimensional c..