11 July 2018
How Planes Fly
Air travel is the most efficient and fastest means of transportation and because of this, millions of people travel in airplanes every day. The process of flying seems very confusing to most people; how the heavy planes carrying a lot of people and a ton of luggage are able to easily glide through the air. To understand the process of flying, it is essential to be familiar with the principle of flight, what type of material they are made of and what fuels them. It is easy to ignore the physics of flight as well as the ways in which we exploit them to achieve flight. We sometimes look at a plane with no greater understanding of the principles involved than a caveman; how do these heavy machines take to the air? Flight in aircraft is an easy process when the right materials and fuel are used and also when the principles of flight which are the Drag, the Thrust, the Lift and the Weight or Gravity are in perfect harmony.
One of the main things considered in the building of an aircraft is the material. A strong and durable but lightweight material is needed for maximum efficiency. The body of most aircraft is made of aluminum because it perfectly fits all the requirement being strong and lightweight, although it is not used as the skin in very fast moving or hypersonic aircraft because it loses its strength at high temperature, in this case, steel or titanium can be used. Steel is about four times stronger and thicker than aluminum but it is also heavier and cannot be used on the body of most commercial aircraft instead it is used in places that strength is a necessity like in the internal parts or on the landing gear and screws. Titanium is stronger than most alloys of steel and it’s also lightweight but it’s not used in most commercial aircraft now because it’s also expensive being remarkable for its strength given its lightweight. Titanium softens at high temperatures and retains its strength; for this reason, it’s used in places like the engine which gets hot.
The fuel plays a big role in the aircraft’s ability to move. The two types of aviation fuel are the jet fuel and the aviation gasoline. Jet fuel is made from paraffin oil and kerosene and its used by most commercial aircraft because of its maximum efficiency and low cost. Jet fuel is sold in bulk to large aircrafts operators such as airlines and the military. Aviation fuel contains highly refined gasoline and is sold to individual aircraft operators. High quality and purity differentiate aviation gasoline and jet fuel from the normal gasoline used in cars, so when the aviation fuel does not pass the quality test to be used for aircraft, they are sold to other companies that do not require high-quality fuel like trains and some big machines. Jet fuel is used in engines that require it to be burnt to ignition like in the turbine engines, but the aviation gasoline is used in spark-ignition engines. Mid-sized commercial aircraft like the Boeing 747 consume approximately one gallon or four liters every second which means that flights that are over 10 hours use approximately thirty-six thousand gallons.
The main forces that allow the steady movement of aircrafts are the drag, the lift, the thrust and the weight or gravity; Airplanes fly because there is no net force acting on them, when no net force is acting on an object, if it’s in rest, it stays at rest and if it’s in motion, it stays in motion. Thrust is the force pushing the airplane forward and this force is produced by a propeller or a jet engine and this causes the airplane to move fast enough to produce lift; drag is the opposite of thrust and its one of the two forces keeping the plane away from the air. The drag is the force pushing against the airplane in the air or the air resistance. The thrust has to be greater than the drag for the airplane to move fast in the air. Lift is the force acting upwards on an airplane keeping it in the air; gravity is the force pulling any object towards the center of the earth so in this case, gravity is the second force acting downwards on an airplane keeping it from the air, so the lift has to be greater than gravity for a plane to ascend.