This week we covered aerospace engineering and chemical engineering. Aerospace Engineering is the engineering that involves the aerodynamic design of airplanes, helicopters, and everything else that deals with aerodyamics and propulsion. This type of engineering is very important to helping our everyday lives. Aerospace engineering helps cover everything from learning about the universe we live in to making the cars we drive more fuel efficient. According to the Sloan Career Cornerstone Center, Aerospace Engineering is ,"creating machines, from airplanes that weigh over a half a million pounds to spacecraft that travel over 17,000 miles an hour. They design, develop, and test aircraft, spacecraft, and missiles and supervise the manufacture of these products." We were able to help further learn this type of engineering by going to the Jet Propulsion Labratory, the California Institute of Technology and Nasa's spacecraft center. In order to help us understand Aerospace engineering better, we had three projects to complete.
The first project we had to build a bottle rocket out of a old two liter bottle. We had to build fins in order to stablize the rocket mid flight and counter act drag. In addition, we had to design a glider that would detatch from the plane at the peak of the flight. We had to predict the time of the flight so we could program an arduino to drive a servo and release the glider. The glider had to slowly descend back to the ground. Also, we had to have a parachute deploy so after the bottle rocket reached its peak, the parachute deployed and helped to slow down the fall of the rocket carrying the arduino circuit. Drag is a mechanical force generated by a solid object moving through a fluid (Sloan and Professor Gray). The other three forces we had to consider when designing our rocket and glider were weight, thrust, and lift. Weight is the force caused by the gravitational attraction from Earth and is also influenced by mass (Sloan and Professor Gray). Lift is another mechanical force generated by a solid object moving through a fluid (Sloan and Professor Gray). Thrust is a mechancal force generated by the engines on an airplane to move the plane through the wind (Sloan and Professor Gray). In this case, the thrust was generated by pumping pressurized air into the bottle, which was already partially filled with water.
Second we had to complete was a remote control airplane. The plane we built was made out of foam. It contained servos to help the plane change it's elevation and turn while motors drove the propellor. This project helped us learn about the center of gravity of an object and how weighting affects the flight of an object. The center of pressure is the point where the aerodynamic forces of lift, drag, thrust, and gravity “act” upon. A good example of the center of pressure is wind striking some object such as a soda bottle. Because of the shape, the wind will hit it differently in different parts of the bottle. If you were to try to calculate and add up all of the force from the wind hitting the bottle, after all of the cancellations, you would find one point that seems to capture all of the wind force. The reason why a plane flies is because the motors generate enough thrust and lift so that the plane is able to get off the ground. One theory behind lift is the Bernoulli Effect. This states that This theory derives from Bernoulli’s Equation: The air moving above a typical airplane’s wing is moving faster than that below. Wings on the plane are angled slightly upwards in order to help this affect. This creates a reduced pressure above the wing causing the wing to move up in response to the pressure difference (Sloan and Professor Gray).
Lastly, we had to build a model rocket out of paper and balsa wood. The paper we used was coated with Elmer's Glue in order to make it strong enough to withstand the pressure of the launches. This rocket also had to deploy a streamer mid flight by having the motor burn out and pushing the streamer out. We learned about the center of gravity and the center of pressure through this project and how these two points on the rocket affect the flight. The center of gravity is the point that we say gravity “acts” upon. It kind of acts as the balancing point. If the center of gravity is over the base of an object, that object will stand. Similar to the airplane, the rocket also had to generate lift. The second theory of why planes fly is derived from Newton's Third law of motion. The air hits the bottom of the wing (because it is at an angle) forces the air down and lifts the wings up. An example of this effect is when people placed their hand outside the window of a moving car. Unfortunately, this feeling of lift could be explained by either. However, the theory of lift comes from a combination of both and is far too complex to simplify in terms of either.