The helicopter.

e [Music] [Applause] modern Aviation has made great progress in recent [Music] [Applause] years huge airliners carry into the sky each day an Ever larger tonnage of cargos and passengers jet propulsion has made possible extremely high [Music] speeds yet in one aspect these aircraft have become more limited acally long runways to take off and land the need for an aircraft independent of huge airfields is being met today by the helicopter which can land in any area big enough for its whirling [Music] rotor helicopters 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 these craft can carry some 400 lb of mail on each trip and in some cities trips are made throughout the day at 20-minute intervals 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 trucks thus greatly speeding the delivery of mail helicopters have found important uses in the country too where they are used for dusting crops which would be damaged by ground equipment the helicopter's great maneuverability makes it possible to spread dust over every corner of the field no matter how irregular it may be the sharp downdraft of the whirling rotor causes dust to swirl among the plants thus giving them a more thorough Co 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 pipelines if anything unusual is spotted from the air the helicopter can hover to give the inspector a better look equipped with pontoons the helicopter can land on water and can penetrate swamp HS which were previously inaccessible in war the helicopter has proved itself for many purposes in addition to its use for observation or direction of artillery fire and for transportation of men and Equipment the helicopter has saved many a Life by its ability to land directly on the battlefield in order to speed wounded men to base Hospital facilities [Music] but all these values will eventually be secondary to the helicopter's use as a passenger vehicle combining its ability to fly with the automobile's ability to go directly to and from its destination this versatile craft is almost unlimited in the variety of uses to which it can be put to understand the helicopter let's first see what makes an ordin Ary airplane fly it isn't the propeller which lifts the airplane off the ground for example jet airplanes can fly without propellers but all ordinary aircraft must have forward speed to fly and this forward speed is provided by the propellers the reason speed is necessary lies in the shape of the airplane's wing a careful examination will show that the wing has been designed so that its upper surface 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 of 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 speeds increases as the airplane itself moves faster and creates a partial vacuum along the upper Wing surface the normal air pressure under the wing lifts it into this partial vacuum which enables the airplane to fly at first glance a helicopter seems to be able to fly without wings actually however the rotor Blades of a helicopter are shaped much like the wings of an airplane the upper surface of the rotor blade BL is more curved than the lower surface when the rotor turns 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 when the blades move fast enough they provide the lift necessary to raise the helicopter off the ground and permit it to hover thus helicopters are called roty Wing aircraft while conventional airplanes are called fixed wings the helicopter's development stemmed from an earlier craft the auto gyro shown in these historical films it required a propeller for power since the rotor was freewheeling and couldn't hover many devices first developed for auto Gyros are being used in today's helicopter the helicopter is a free swinging body hanging from the whirling rotors the Turning rotor sets up an action which tends to turn the body of the helicopter in the opposite direction this action is called torque and is counteracted 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 it will fly straight up but if you tilt it in any direction it will fly in that direction a helicopter rotor works the same way tilting it in any direction with relation to its shaft 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 be as thoroughly trained as the pilot of any other type of aircraft a selfstarter starts the engine and after a careful warmup we're ready to take to the air [Applause] the collective pitch control whose handle is also the throttle determines the amount of lift which the rotor provides once in the air the pilot uses foot pedals which control the tail rotor to turn the machine in the direction he desires the stick in front of the pilot controls the angle between the spinning rotor and its shaft when the stick is moved in the direction the pilot wants to travel the helicopter is on its way flying a helicopter is quite a different experience from flying a fixed Wing craft although this craft can cruise at about 85 mph there's no need to maintain air speed so there's time to look around should the engine fail the rotor would act much like a parachute to permit an emergency landing but of course most Landings are with power there are a number of different kinds of helicopters being flown today [Music] some are designed with two rotors which turn in opposite directions each rotor counteracts the torque action of the other and thus eliminates the need for an anti-torque tail rotor twin rotor helicopters have been built large enough to carry 16 persons with a gross weight of more than 14,000 lb the jet helicopter powered by tiny jet engines on the tips of the rotor blades works much like a fireworks pin wheel the jet engines are the only source of power jet helicopters are simpler in 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 unprecedented freedom of movement and the wi wide range of uses to which they can be put hold great promise for the future of Transportation who could have predicted the vast changes which the development of the automobile and the truck have brought about in our society the potentialities of 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 a [Music]