To test how aerodynamics affects efficiency, I have been using an airfoil simulator, developed at the NASA Glenn Research Center, which allows me to observe the airflow around different shapes of airfoils. The simulation software permits me to test how a wing that I have designed is able to cope with airflow that is simulated in an air tunnel. My initiative in using this program was to determine what affects in the design of a plane’s wing would increase efficiency by increasing lift, reducing drag, and reducing mass.

In general, the size of the wing is defined by its span (the distance from wing tip to wing tip), its chord (the distance from leading edge to trailing edge), its area (span multiplied by chord), and its aspect ratio (the ratio of the span to the chord).

For the first trial, I measured the lift generated from a plane wing’s that has a span of 100 feet, a chord (the thickness of the wing) of 5 feet, and an area of 500 square feet. The lift recorded in this trial was 7,755 lbs while the drag was 340 lbs.

For my 2^nd trial, I increased the span of the wing from 100 feet to 125.1 feet and increased the area of the wing from 500.5 feet squared to a 625.5 feet squared. As a result of this change, the lift generated increased to 9,711 lbs and drag increased to 403 lbs.

Lift is directly related to the surface area of the wing and is perpendicular to the flight direction. If you double the surface area of the wing, the lift generated doubles. Increasing the wingspan while keeping the chord constant (which increases the aspect ratio) leads to a higher lift to drag ratio (displayed as L/D in the images). This indicates how a longer wingspan leads to a gain in lift while enduring a smaller drag penalty. However, the challenge is how you increase the wing area without having to add more weight. A larger wing area results in more materials and structures used in the design, leading to an increase in the weight.

Throughout my internship, I have been using several simulation programs endorsed by NASA where I am able to input theoretical values that affect the principles of aerodynamics and observe what the result may be. Each simulator was used to determine the most ideal environment for flight efficiency and how the design of the aircraft must be altered in order to adapt to such environmental changes. The first program I used was an engine simulator where I explored how a jet engine produces thrust by interactively altering the different engine parameters.

The software allows me to choose from four different types of engines. After I have selected an engine, I am able to alter the speed (measured in kilometers per hour) generated by the turbine as well as what altitude the plane is flying at. Here is an image of my first design of a J85 jet engine where I had set the speed of the engine to 845 km/h and the altitude at 14,333.33 meters.

 
After observing what effect the initial altitude the jet engine had on the engine performance, I decreased the altitude that the aircraft would travel and compared the values of engine performance. As the altitude decreases, the net thrust, gross thrust, and core airflow increases. One specific factor that determines the efficiency of an aircraft's performance is a Thrust Specific Fuel Consumption factor (TSFC). When the speed, altitude, or throttle is increased, the TSFC increases which means that the aircraft becomes less fuel efficient. A lower TSFC value means that the engine is more fuel efficient. Since the altitude has decreased in the second picture, the aircraft is more fuel efficient.

 
As my internship continues, I will be explaining more about how efficiency alters through changes certain variables in these simulation programs.

One of the most vital parts in improving efficiency in flight is improving fuel efficiency. An improvement in fuel efficiency permits a plane to travel at higher altitudes, further distances, and use more power while not consuming too much fuel. The heavier the airplane is, the higher the maximum efficiency speed is, and to achieve the true maximum range, the aircraft must slow down as fuel burns to maintain the same angle of attack and drag. The altitude a plane ascends also effects fuel efficiency. The higher the altitude a plane ascends, the less dense the air is, enabling the plane's turbine to produce less power and save fuel. An optimum altitude exists for every turbine aircraft at its given weight.

In the aviation industry, fuel efficiency is measured through specific range, which is the number of miles the airplane has traveled through air per pound of fuel consumed. Here is an example of how a specific range is determined. A business jet flying at 440 knots and burning 1,200 pounds per hour has a specific range of 0.37, which is satisfactory for a jet. Specific range calculations make it easier to compare the fuel efficiency between planes and enables engineers to develop a strategy where they can address an issue and improve fuel efficiency.