question for people who know about aeroplanes, possibly a bit of the physics behind it as well...?

Question

a flying aeroplane experiences loads of forces.....thrust, drag, lift, and weight or gravity. i know that when a plane is cruising, thrust and drag cancel each other out and similarly, lift and weight cancel each other out because both pairs consist of equal and opposite forces.
however, i found out that when a plane is accelerating or decelerating, taking off or landing, it experiences some forces (either thrust, drag, lift, weight or all of them at the same time). I know this must be a very confusing question for people who know a lot about aeroplanes, but i am just a A level student, doing a presentation on fibreglass in which i do this calculation showing that fibreglass is a suitable material for using in the new Airbus A380. i don't have to go so much into the physics of flying aeroplanes so this much information is fine for me.
i calculated the pressure experienced by the plane by Force/Area, does the answer 3.06 kNewtons/m2 seem like a very small pressure on an airbus A380?

Answer 1

You're on the right track. When the plane is cruising, the engine needs to provide enough thrust to overcome the drag and also provide a little lift. At cruising altitude, the air is much less dense than at sea level. But when taking off, the engine also needs to accelerate this huge mass from zero to cruising speed, and also provide some of the lift that isn't provided by the wings because the plane isn't moving fast enough. That's the hard work.

For landing, it can be enough just to cut back on the engine and let the drag slow the plane. As it slows, engage the flaps to maintain lift, while increasing the drag even more.

Answer 2

It's not clear what force and area you used to calculate the pressure you refer to. One of the more often used parameters is the weight divided by the wing area. Using the published values of 560 tonnes and 845 m², I get about 6.5 kN/m². This is a typical value for jet transport planes.

The accelerations of a plane come from changing the thrust value or changing the angle of attack of the wing (longitudinal and normal accelerations, respectively). There are also other means to accelerate such as flap, spoiler and landing gear deployment. All of these effects are normally of short time duration, and the aim of every flight is to have the accelerations noticed as little as possible by the passengers.

Answer 3

If the plane is moving, thrust>drag right? if plane is rising, Lift>Weight, Right. Not equal and opposite forces.

Answer 4

you wont have just one force, it will very depending on the location on the plane, frontal surface will have forces perpendicular to the surface at the forwardmost point, near an engine you will have forward force as well as torque forces,etc.. may want to narrow your material to a single piece of the plane with a known force acting on it such as a landing strut, or fixed frame section