one aspect these aircraft have become more limited than before since they need exceptionally long runways to take off and land the need for an aircraft independent of huge airfield is being met today by the helicopter which can land in any area big enough are being used today for a wide variety of jobs which can't be handled by other aircraft in larger cities they are delivering thousands of pounds of mail every day from outlying airports directly to the post office  can carry some four hundred pounds of mail on each trip and in some cities trips are made throughout the day at quite a method interval flying over city traffic the helicopter can land directly on the roof of the post office itself in a fraction of the time needed by mail truck greatly speeding the delivery of male  about important uses in the country to where they are used for dusting crops which would be damaged by ground equipment but helicopters great maneuverability makes it possible to spread over every corner of the field no matter how the helicopter's slow speed makes it useful for any kind of air search and especially for inspections of such things as power lines and pipeline if anything unusual is not from the air the helicopter can hover to give the inspector a better look equipped with sun tunes the helicopter can land on water and can penetrate swamps which were previously inaccessible in war the helicopter has proved itself for many purposes in addition to its use for observation for direction of artillery fire and for transportation of men and equipment the helicopter has saved many a life by its ability to but all these values will eventually be secondary to the helicopters used as a passenger vehicle combining its ability to fly with the automobiles with the ability to go directly to and from its destination this versatile  to understand the helicopter let's first see what makes an ordinary airplane fly it isn't that color which lifts the airplane off the ground for example jet airplanes can fly with africa but all ordinary aircraft must have forward speed to fly and this forward speed is provided by the propeller the reason speed is necessary lies in the shape of the airplane's wings a careful examination will show that the wing has been designed so that proper service is more curved than its lower surface therefore the distance from the front to the back of the wing measured along the lower surface is less than the distance from the front to the back measured along the upper surface when the airplane is in motion air rushes past the wing the air passing the upper surface moves a longer distance in the same time as the air passing the lower surface and therefore moves past the upper surface faster this difference in air speed increases as the airplane itself moves faster and creates a partial vacuum along the upper wing surface the normal air pressure under the wing lifted into this partial vacuum which enables the airplane to fly at first glance the helicopter seems to be able to fly without wings actually however the rotor blades of the helicopter are shaped much like the wings of an airplane the upper surface of the rotor blade is more curved than the lower surface around here turn air moves past it in much the same way that it moves past the wing of an ordinary plane thus there is no need for the helicopter itself to be moving the helicopter's development stemmed from an earlier draft the auto gyro shown in these historical films it required a propeller for power since the rover was pretty wheeling and couldn't hover many devices first developed for a gyros are being used in today's helicopter the helicopter is a free swinging body hanging from the curling rotor the turning rotor it sets up an action which tends to turn the body of the helicopter in the opposite direction this action is called torque and discover acted by a tail propeller called the anti torque rotor the tail rotor is used to turn the craft in any direction independently of the direction of travel to understand how forward movement is accomplished let's see what happens with a toy rotor like this if you hold the rotor flat for flies straight up direction helicopter rotor works the same way tilting it in any direction with relation to its shadow causes the helicopter to fly in that direction whether it's forward backward or sideways the direction of flight is determined by the tilt of the rotor and not by the direction the nose of the helicopter is headed now let's take a ride in a helicopter while the controls are comparatively simple a helicopter pilot must the early train the pilot does any other type of aircraft a self starter starts the engine and after a careful warm up we're ready to take to the air the stick in front of the pilot controls the angle between the spinning rotor and when the stick is moving in the direction the pilot wants to travel the helicopter is on its way helicopter is quite a different experience from flying a fixed wing crash although this craft can cruise at about eighty five miles an hour there's no need to maintain airspeed so there is time to look around the engine fails the rotor would act much like a par te to permit an emergency landing but of course most landings are without power there are a number of different kinds of helicopters being flown today some are designed to run which turn in opposite direction each rotor counteract the protection of the other and thus eliminates the need helicopter powered by tiny jet engines on the tips of the rotor blade works much like a fireworks pinball the jet engines are the only source of power jet helicopters are simpler and construction lighter and easier to operate than conventional helicopters although fuel consumption is very high the continued development of this and other types of helicopters with their under president freedom of movement and the wide range of uses to which they can be put great promise for the future of transportation who could have predicted the vast changes which the development of the automobile and the trucker brought about in our society the potentiality is that the helicopter are just as great its versatility as a transportation vehicle may eventually play an important role in reshaping the pattern of our daily living