Tools of Aeronautics Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Tools of Aeronautics

Tools of Aeronautics Four tools test aeronautics hypotheses Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Tools of Aeronautics Four tools test aeronautics hypotheses Wind tunnel testing Computational fluid dynamics Flight simulation Flight test Testing tools were developed only within the last 100 years On one hand the evolution of aeronautics testing tools was dependent on the development of technology, and on the other hand, their evolution pushed the technology faster and to greater heights. Each tool has its own niche in the design cycle of a new airplane or in the modification of an existing one. Data from one tool can feed into the tests performed using another tool. Oftentimes, research will be completed using one tool and proceed on to another, only to return to the previous tool because of a new question generated during testing. Researchers select the appropriate tool based upon the information being sought. A tool that can provide excellent data on, say, the aerodynamics of a wing may not be able to give any information about how that wing affects the control of the entire airplane.

Wind Tunnel First tool to be developed Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Wind Tunnel First tool to be developed Used since the time of the Wright brothers Moves wind past a stationary object instead of moving the object through the air Advantages Safer Cheaper Controlled environment Safer than using a pilot to test fly a plan with unknown characteristics. Individual parts may be tested for their behavior to airflow before assembly into a final product. While wind tunnels for research are not cheap, they are considerably less expensive than, again, test flights. Fewer uncertainties – no influence of weather, changes in wind speed and direction – everything is constant.

Wind Tunnel Disadvantages Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Wind Tunnel Disadvantages Creation of wind tunnel airflow requires a lot of energy. Maintenance of machinery, equipment, and tunnels is expensive. Airplane models must be made with precision and durability, which requires time and money.

Computational Fluid Dynamics Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Computational Fluid Dynamics Idea conceived in the 1960s to run wind tunnel tests in a computer Initial computers were large, slow, and cumbersome Computers were able to accurately predict forces and pressures Computers were able to graphically display fluid forces on an object

Navier-Stokes Equations Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Navier-Stokes Equations Navier-Stokes equations are a complicated set of equations that define the flow of air around an airfoil. Computational fluid dynamics solves these equations (or a simplified version – dependent on application). Aren’t you glad we have computers that perform these computations for us?

Computational Fluid Dynamics Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Computational Fluid Dynamics Note the grid around the complex airfoil. In this example the airfoil has a leading edge flap and a trailing edge flap. Each of the three sections are modeled separately. Note the three overlapping grids. The intersection of each line is a node. Computation Fluid Dynamics (CFD) calculates the air flow properties (pressure, temperature, velocity, density, etc.) at each node. The solution at each node is a function of the neighboring nodes. The solution is achieved by guessing an answer, then repeating the solution until the answer stabilizes. Such calculations are typically performed by large computers, and even such computers require a great deal of time to arrive at a solution. This simplified approach is used in FoilSim.

Computational Fluid Dynamics Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Computational Fluid Dynamics This Air Foil Simulator is an example of simplified computational fluid dynamics. The software integrates the pressure around the air foil and calculates lift and drag.

Computational Fluid Dynamics Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Computational Fluid Dynamics Many models are so complex that hours are needed, even with today’s computers, to analyze the data. Graphics present an incredibly large amount of complex information in a manner that enables researchers to quickly and accurately draw conclusions from their data.

Flight Simulation Two Primary uses of flight simulation Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Flight Simulation Two Primary uses of flight simulation Training Research Training Enables pilots to learn to fly new airplanes and perfect skills prior to actually flying new airplanes Trains pilots to handle emergency situations Research Examines the handling qualities of an airplane Complex computer-based control systems used to help the pilot fly high-performance airplanes. These control systems must be extensively tested and fine-tuned before they are incorporated into a real airplane.

Flight Simulation How Does It Work? Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Flight Simulation How Does It Work? Similar to CFD, a math model of the test plane is programmed into a computer. The computer controls a cockpit mock-up designed to look like the interior of an airplane. A motion system simulates the movements of an airplane. Computers create scenery for the pilot. Sound systems and instruments work together to provide the pilot with an extremely realistic flying environment.

Flight Test Final phase of flight development Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Flight Test Final phase of flight development Flight testing verifies predictions made in prior phases of flight development Based on the results of a flight test, an airplane may be tested further using one of the other three tools, or more flight tests may be recommended. Flight tests require advance planning and preparation. Instruments are placed in the airplane to record forces, pressures, control surface movements, pilot movement of controls, and radio communications. Every possible bit of information about the flight is recorded. On the ground, tracking stations are set up. Microphones and cameras are readied. Barometers, thermometers, and anemometers are installed to record the environment during the flight. A precise and exhaustive list of all maneuvers that researchers want the pilot to fly are compiled in a test plan. Every action of the pilot, from takeoff to landing, is prescribed in this test plan. A test pilot receives hours of training, not only on how to fly and how to handle emergency situations, but how to accurately report what he or she is seeing, feeling, and hearing throughout the flight. Test pilots wear a flight suit with snaps and straps that allow them to strap the test plan to one leg and a notepad to the other. Everything the pilot says is recorded and analyzed. A test pilot must be able to follow the flight plan precisely. If something goes wrong, the test pilot must quickly determine the cause of the problem and its severity. It is a point of honor for all test pilots to land their airplane. One of the most difficult but also the most challenging decisions a test pilot must make is whether the airplane is still flyable when a problem arises. Unfortunately, history has seen test pilots who have "stuck it out" thinking they could successfully land the airplane, when in fact they couldn't. Being a test pilot is an incredibly demanding and dangerous occupation. The advent of flight simulators and CFD has helped reduce the risks of flight testing by allowing for a more mature design prior to testing.

Tools of Aeronautics Gateway To Technology® Unit 4– Lesson 4.2– Aeronautics Image Resources Microsoft, Inc. (2008). Clip art. Retrieved September 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx National Aeronautics and Space Administration (NASA). (2008). NASA Dryden flight simulator photo collection. Retrieved June 24, 2009, from http://www.dfrc.nasa.gov/Gallery/Photo/Simulator/index.html National Aeronautics and Space Administration (NASA). (2008). Navier Stokes equations. Retrieved June 24, 2009, from http://www.grc.nasa.gov/WWW/K-12/airplane/nseqs.html National Aeronautics and Space Administration (NASA). (2009). NAS software applications. Retrieved June 24, 2009, from http://www.nas.nasa.gov/Resources/Applications/applications.html National Aeronautics and Space Administration (NASA). (2009). Computational fluid dynamics. Retrieved June 24, 2009, from http://www.dfrc.nasa.gov/Gallery/Photo/X-43A/HTML/ED97-43968-1.html