Manual

this edge, its flow is disrupted and reroutedto go over, under, and around thewing surface. Deflected air changesspeed as it is forced past the wing. Airmoving over top of a wing surface movesat a greater speed than the air movingbelow. Since slow moving air has a higherair pressure, the higher pressure underthe wing surface pushes on the bottom ofthe surface causing it to rise. This, in anutshell, is the basic secret to heavierthan-airflight.Forward motion is very important inproducing Lift. The faster a wing surfacemoves, the greater the volume of air thatforced past it. As the volume of airincreases, the volume of air beingdeflected downward increases as well.This results in a greater pressuredifferential between the air above and theair below the wing.Confused yet? Let’s simplify matters andstate that Lift is the force which directlycounter-acts an aircraft’s weight duringflight. For example, if your F-14 weighs80,000 lbs. then your wings must produceexactly 80,000 lbs. of Lift to maintain levelflight, not 79,999 or 80,001. Any Liftproduced above or below this number willcause the aircraft to change altitude.Gravity (Weight)“Whatever goes up, must come down.” Allobjects (animal, vegetable, and mineral)fall toward the centre of this planet at aconstant rate of roughly 32 ft. /second 2 .As a practical matter, gravity holds thingsdown and keeps them from flying off intospace. In fact if it wasn’t for gravity, life aswe know it wouldn’t exist.Gravity works at cross purposes to Lift. Itmust constantly be overcome by Lift inorder for anything to remain airborne forvery long. In level flight, Lift forces ouraircraft away from the Earth’s surface justas gravity pulls it downward. If the force ofGravity becomes greater than the Liftbeing exerted, the object will be drawntoward the ground, eventually ending theflight. So, while we all must appreciate thebeneficial effects of gravity, it surepresents problems for those of us whowant to fly.See the section on G Forces for moreinformation on the affects of gravity.ThrustModern fighters have fantasticperformance envelopes due to thetremendous amount of power their jetengines can produce. This power isknown as Thrust.Thrust is the aerodynamic force whichpropels an object through the air. Itmakes no difference if the object is pulledthrough air by a propeller or pushed frombehind by a jet engine. The purpose ofThrust is to force air across the aircraft’swing surface in order to create Lift. Aslong as the aircraft maintains a level flightattitude increasing the amount of Thrustresults in a corresponding increase in Lift.G-Forces when banking. As you can see theflight attitude (bank angle) that an aircraftassumes while turning has a direct relationshipto the number of G s inflicted on the aircraftand pilot.