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

2. 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.

3. 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.

4. Wind Tunnel Disadvantages
Tools of Aeronautics
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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.

5. Computational Fluid Dynamics
Tools of Aeronautics
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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

6. Navier-Stokes Equations
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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?

7. Computational Fluid Dynamics
Tools of Aeronautics
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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.

8. Computational Fluid Dynamics
Tools of Aeronautics
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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.

9. Computational Fluid Dynamics
Tools of Aeronautics
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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.

10. Flight Simulation Two Primary uses of flight simulation
Tools of Aeronautics
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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.

11. Flight Simulation How Does It Work?
Tools of Aeronautics
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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.

12. Flight Test Final phase of flight development
Tools of Aeronautics
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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.

13. Tools of Aeronautics
Gateway To Technology®
Unit 4– Lesson 4.2– Aeronautics
Image Resources
Microsoft, Inc. (2008). Clip art. Retrieved September 10, 2008, from
National Aeronautics and Space Administration (NASA). (2008). NASA Dryden flight simulator photo collection. Retrieved June 24, 2009, from
National Aeronautics and Space Administration (NASA). (2008). Navier Stokes equations. Retrieved June 24, 2009, from
National Aeronautics and Space Administration (NASA). (2009). NAS software applications. Retrieved June 24, 2009, from
National Aeronautics and Space Administration (NASA). (2009). Computational fluid dynamics. Retrieved June 24, 2009, from