ASC3471 Physiology of Flight
Mr. Kirk Webster
As far as any one individual can remember, as a child they loved going fast. There is that brilliance of feeling oneself being propelled forward, and their weight being caressed in a seat. This is a sensation felt in many vehicles, cars, high speed motor boats, motorcycles and last but not least the aircraft and spaceship.
In the world of flying, there are many elements and variable to consider in the operation of an aircraft. In reality, an aircraft is actually a very simple machine, which when designed properly can accomplish the feat of defying gravity. In ground school, we are taught the basic fundamentals of flight. One of which is the four forces of flight. Not to beat a dead horse but here it what we already know. There are four forces that are always consistent and ever present on an aircraft. The National Aeronautics and Space Association (NASA) does a very good job at identifying and defining these terms. They are:
Thrust – “a force which moves an aircraft in the direction of motion. It is created with a propeller, jet engine or rocket.” (With the exception of the rocket.) “Air is pulled in and pushed out in the other direction. Think of a household fan.”
Drag – “the force which acts opposite of the direction of motion. It tends to slow down and object. Drag is caused by friction and difference in air pressure. An example would be sticking your hand outside of a moving car window, and feeling it pull back.”
Weight – “Is the force caused by gravity.” Gravity is a terrestrial force that pulls all matter to it.
Lift – Very specific of its name: “Lift is the force that holds an aircraft in the air.”
As we break away from the force of flight, it must understood that when an aircraft is in the air, it is in motion. Acceleration can be considered a by-product of thrust. Since it is a force, it has an affect on the body at the different axis’ of motion. In dealing with the marriage between acceleration and flight, one of the results is the G-force. The G-Force is the sum of “non-gravitational forces that act on an objects freedom to move.” Gforces.net explains further, by stating that it is the “force of gravity on a particular extraterrestrial body or the force of acceleration anywhere.” Now that G-Forces have been covered, and a brief explanation as to what it is, it’s time to view the main topic of discussion. Acceleration. What is Acceleration? The answer provided by Dr. Richard O. Reinhart M.D. and author of the Third Edition of “Basic Flight Physiology” had this to say. Acceleration “is the rate of change in velocity and is measured in G units.” In laments terms, it’s the force upon the body while it is in motion. The G Unit is the G Force, or the force of the Earths Gravitational Pull against the human body while it is in motion. There are three types of acceleration. The reason for this, is that due to the range of motion, which explained earlier as being fairly dynamic. These forms of acceleration are identified by their influence over speed and direction. The first of the three is Linear Acceleration. Linear Acceleration is an increase in velocity of speed without altering the trajectory of the craft or object. A clear example of this would be a person driving their car on a flat straight road, and then flooring the gas pedal causing an increase in speed. The second, is Radial. Radial Acceleration in other realms known as Centripetal, occurs with any change of direction, without altering your rate of travel. In flight school, prospective pilots are taught, ‘standard rate turn.’ A turn which without any variation in air speed, will take approximately two minutes to complete a three hundred and sixty degree turn. The third is “Angular Acceleration.” This occurrence happens when both velocity and trajectory are changed. A spin