why do planes falls down from the sky?
439960
According to the Bernelli principle it is because the ratio of high-speed wing over the TOP of the foil of the wing is not sufficient to generate lift.  Therefore gravity takes over and it falls back to earth.
773547
This is because they were desinged to be able to take off and stay suspended in air while moving foward. if they all oversudden moved reverse they would crash since the wouldnt be able to force themselves up due to their bodies desing.\nMake a paper plane then throw it foward. then try throwin it rear facing front (infact it will turn up then crash down due to the resistance of air to the bodys movement)
1063847
There is no proof. All the evidence disappeared to China or the bottom of the ocean. Why were they so quick to get rid of that steel? Do you really believe that jet fuel gets hot enough to collapse an I beam? Hell, I've picked out beer cans after a bonfire. Duh! And as far as I know, airliners aren't made for knocking down buildings. They are light so they can fly. Have ever seen a crash site? There usually isn't a whole lot of recognizable things left. A building that would collapse after getting hit like that wouldn't pass a NYC building code exam.
501575
the dimpling creates an aerodynamic effect that allows them to stay aloft longer.  \n\ninterestingly, the same effect occurs on the Mig29.  although, there it is an accident.  poor manufacture, not design causes the dimpling.
1077123
The extant videos of the " crash site " of flight 93 show no sign of large debris. One of the plane engines was found thousands of feet away. The cordoned off " debris fieled was 9 miles wide. You tell me. Did this airliner crash into the ground or disintigrate in the air?
984497
1) Ironically, these are usually bright orange - not black, and an orange plane would look dumb.\n2) The plane would be too heavy to make it off the ground.\n3) The "black boxes" are able to survive because of their small size and lack of joints. If they were the size and shape of a plane, they wouldn't be able to withstand the same kind of stress.
1177603
well, it's the area of the wing of the lifting surface, the weight of the plane, along with the pitch angle witch can be adjusted to generate more down force, but a high pitch angle would cause the plane to stall and maybe crash, also the altitude; planes can fly slower at lower altitude because the air is more dense there which means that less speed can generate enough life for it to fly..
401679
Lift. The shape of airplane wings (curved on top, flat on bottom) allows air to pass over them at different speeds, creating a pressure gradient. Higher pressure is built up underneath the wing, allowing for lift to carry it off the ground. For this to work, the airplane must maintain a minimum rotation speed to get off the ground (in a Cessna 150, that speed is about 90mph). Once in the air, the plane can reduce its speed and often glide, however when an aircraft looses too much speed, it looses lift and stalls out.
36148
Occasionally, jets will pass through a section of air that is thick with moisture, but not solid enough to form a cloud.  When the planes wings pass through the moisture, condensation builds on the wings (sometimes causing ice build-up).  When the disturbed moisture rolls off the wings, it mixes with other moisture in the air, condensing into a cloud-like substance, resulting in the white line you see from the ground.
506884
This design cant pull enough air down fast enough to achieve lift. The key to flight is the airfoil shape of the wing or helo propeller. Its naturally causes high pressure under the airfoil as air moves rapidly over it. Thats where lift is achieved.
452551
Big time.  Wind has a extreme effect on planes, especially small ones.  It will blow the plane off course unless the plane is "Crabbed" into the wind.  \n\nWhen tstorms are coming in or going out, there are things called microbursts which is wind that flows straight to the ground.  This will cause planes to crash.\n\nFlying in the rain is not a big deal, but if there's low clouds you'll have to fly IFR (instruments and not visually).  This is a separate rating which I hope to get some day.
213534
They stay in the sky because they are part of our atmosphere. \n\nDefinition of a cloud - A visible body of very fine water droplets or ice particles suspended in the atmosphere at altitudes ranging up to several miles above sea level. \n\nThey aren't forced to drop to the ground unless they become larger droplets or bigger ice particles forcing them down by gravity - which is what would be rain or a storm.
1159258
People first thought it was cursed, but recent discoveries show that is most likely due to Methane gas which bubbles up to the surface. When methane reacts with oxygen, it is the perfect cause for a disaster. Also when methane rises in the air, it can easily shut off the engine of a plane, causing it to spin out of control and crash.
25793
Because of the jet stream.  The jet stream flows west to east.  When a plane is flying east to west, the is more wind resistance on it.
134741
it is called terminal velocity, at one point no matter the mass, size or shape of an object everything will reach an equilibrium between the gravitational force pulling the object down to earth and the friction the atmosphere causes to slow the fall. If dropped high enough the rate of fall will be constant for any object, the best point to illustrate this is when parashooters all jump at different intervals but all reach a point where they are all falling at the same velocity and time.
426165
Birds could fly with only 1 wing if if was "falling" in one direction, if not, then it can not fly. \nHuman Nature, people always want to be better than each other
667234
I will be damned if I know, lol, but, I am about to- but hope to never need to use one:)\n\nParachutes work because of something called ‘air resistance.’ If there were no air resistance, then gravity would cause everything to fall at the same rate, so no matter what item you dropped (i.e. a feather or a rock), it would hit the ground at exactly the same time (assuming you dropped it from the same height). But air resistance complicates things (and makes sky-diving a lot more fun). Air resistance happens because as things fall, they have to push their way past the atoms and molecules that make up air in order to get where they’re going.\n\nFor something like a rock, this isn’t really a big deal, since rocks tend to be really heavy while being pretty small, so they can push the air molecules out of the way quite easily. But things like feathers can’t push the air molecules out of the way very well – for one, they weigh less so they don’t push as hard. And for another, they’re pretty big, so they run into a lot more air molecules than the rock does. So the air actually slows the feather down.\n\nThis is what makes parachute work. If a person were to fall without a parachute, they’d push the air molecules out of the way very easily, so the air wouldn’t be able to do much to slow the person down. But if the person is attached to a parachute, then the parachute will run into lots of air molecules, and especially if it’s curved to be higher up in the middle, it will be very hard for the air molecules to get out of the way. If they can’t get out of the way, they will slow the parachute (and hence the person) down. \n\nAnother way to put it:)\n\n    *  A parachute works to slow down someone or something from falling by creating “drag”.\n    * Drag is the push on something from air or water.\n    * Because air is much thinner than water it doesn’t have as much drag.\n    * The bigger something is – the larger it’s surface area the more drag it creates.\n    * That’s why a parachute works so well – it’s very light and it has a very big surface area. It catches lots of air in it as it falls so it creates lots of drag which slows it down as it falls. \n\nHope you are happy now, I am still NOT jumping out of an airplane, lol