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the Lewis flight Propulsion Laboratory

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of the national advisory committee for

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aeronautics has investigated the

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problems of survival in light airplane

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accidents because this type of accident

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is responsible for many of the

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casualties of civil aviation it was the

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purpose of this work to determine how

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people are injured during such crashes

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in order to obtain the desired

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information on crash survival several

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small tamdan to place light airplanes

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were crashed a stall spin accident was

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chosen for study such an accident occurs

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when an airplane stalls and enters into

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a spin during a landing approach the

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airplane is too close to the ground to

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recover from the spin a survey made by

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Cornell crash injury research indicated

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that this type of accident is a frequent

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source of fatalities in light airplane

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crashes to simulate such a crash the

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axis of the crash was rotated the ground

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was simulated by a mound of Earth and

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the airplane ran along the ground in a

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level attitude to strike the mound of

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earth the mound was located so that the

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airplanes left wing tip left landing

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wheel and the cell would strike at the

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same time in the same manner as in the

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stall spin accidents that were being

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simulated two dummies were installed in

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the airplane the dummy in the front seat

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was a standard Air Force dummy used in

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the testing of parachutes in the

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construction of this dummy no attempt

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was made to simulate the resilience of

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the human body although the mass

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distribution of the component parts was

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similar to that of a human being an Air

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Force anthropomorphic dummy was

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installed in the rear seat this dummy is

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a reasonable replica of the human body

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in both mass distribution and resilience

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of human tissues motion pictures were

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taken from various vantage points around

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the crash site these motion pictures

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show how the dummy passengers moved

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during the crash and how the airplane

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structure deforms meanwhile the

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telemeter transmitting station carried

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in the airplane radioed the crash loads

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measured on the passengers and in

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not fit the transmitted data were

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recorded by a receiving station at the

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crash site three crashes were made in

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this investigation the airplanes were

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propelled by their own power along a

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runway toward the crash barrier a

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slipper mounted on a monorail guided

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each airplane into the barrier the speed

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of the airplane at impact in the three

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crashes was 60 47 and 42 miles per hour

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the motion pictures obtained verify that

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most of the injuries that result from

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light airplane accidents are caused by

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the occupant striking part of the

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airplane inside the cockpit these

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injuries occur in two ways when the

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airplane structure collapses and strikes

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the occupant this happens to the

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the occupant can also be injured when he

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is improperly restrained and moves from

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his normal position to strike objects in

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the cockpit as illustrated here by the

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occupant in the rear seat the next

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motion picture sequence of the 60

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mile-per-hour crash shows how the front

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of the airplane collapses and crushes

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the dummy in the front seat now watch

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the dummy in the front seat the red

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liquid that obscures the airplane in the

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latter part of the pictures was used to

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there is little chance that the occupant

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in the front seat would survive such a

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crash the lower part of the dummy was

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trapped in the collapsing airplane

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structure the instrument panel moved

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rearward and the dummy's head hit it

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with sufficient force to leave a dent

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even if the estimate panel is not pushed

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rearward an improperly restrain document

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may hit it with his head this is

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illustrated in the next motion picture

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sequence of a crash which takes place at

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42 miles per hour even though the

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fuselage force structure was not pushed

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back into the front dummies lap the

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dummy struck the instrument panel

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because he was restrained only by a

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seatbelt and his torso was

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free to move again what's the dummy in

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the front seat as before the dummy in

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the front seat struck the instrument

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panel the neck of the dummy in the rear

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seat broke because of an imperfection in

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its construction injuries of this type

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are not likely in an actual crash here

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these results explain why the survey

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conducted by quenelle crash injury

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research found so many head injuries in

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actual crashes this survey found that

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head injuries were inflicted in

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eighty-eight percent of the accidents if

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an occupant is not to be injured when

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wearing only a seat belt for restraint

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sufficient space must be clear ahead of

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the occupant to allow him to flex over

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the seat belt the occupant in this

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airplane was restrained by only a seat

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belt the front seat and rear control

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stick were removed so that there was

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sufficient room for complete flexure of

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the dummy's torso the torso of the dummy

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moved forward and downward until the

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chest contacted the thighs it is

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apparent that if injuries resulting from

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contact with solid structure are to be

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avoided when using only a seat belt for

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restraint a distance of about 45 inches

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ahead of the seat must be free of any

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solid objects this much of a clear space

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is seldom available in an airplane this

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dangerous movement is reduced to safe

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values when the occupant is properly

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restrained by a seatbelt and the

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shoulder harness the dummy in the rear

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seat in the next crash for a seat belt

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and a shoulder harness this dummy moved

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forward and out of his seat about eight

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to ten inches the forward movement was

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limited by the harness in the most

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forward position the torso is about

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vertical notice this action in these

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slow motion pictures of the crash what's

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here again the Donnie lost his head due

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to a weakness in the next structure of a

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dummy this would not have happened to a

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if a harness is made of material that

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stretches excessively the occupant may

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still strike objects inside the cockpit

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the harness restraining the rear dummy

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in the 60 mile-per-hour crash stretched

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sufficiently to allow the dummy's head

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to strike the back of the dummy in the

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front seat this situation was aggravated

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by the collapse of the structure between

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the front and rear seats this moved the

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front dummy rearward again watch the

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dummy in the rear seat unfortunately the

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fuel missed obscured the actual impact

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of the dummy's head with the front dummy

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however a post-crash inspection revealed

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here is the position of the dummy's head

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when it struck the front dummy it has

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been shown that some of the benefits of

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a shoulder harness are lost if the

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harness stretches excessively in the

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crash if the restraining harness is to

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serve its purpose it must not break in

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order to tell the designer how strong to

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make this harness the forces in these

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traps were measured in the crashes to

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obtain this information tensiometer

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zeeeee were located at each end of the

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seatbelt and on the common juncture of

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the shoulder harness the sum of the

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forces on each end of the seatbelt and

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the force measured in the shoulder

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harness in the 60 mile-per-hour crash

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for the dummy in the rear seat are

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plotted against time after the impact

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with the barrier the seatbelt

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restraining force has two peaks one of

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four thousand pounds and a second of

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3,200 pounds the major seatbelt forces

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endured for about one tenth of a second

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the combined pole on both shoulder

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harness traps is approximately equal to

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half that of the seatbelt showing that

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the seatbelt supported most of the load

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the restraining forces in the seatbelt

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were higher when the passenger was

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restrained by a seatbelt only even when

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the impact speed was reduced from 60 to

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47 miles per hour during the 47

197
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mile-per-hour crash in which the dummy

198
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was restrained only by a seatbelt peak

199
00:10:09,960 --> 00:10:06,880
seatbelt forces were 4,400 pounds and

200
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3,000 pounds as compared to a peak of

201
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4,000 pounds for the seat belt for the

202
00:10:19,140 --> 00:10:17,470
60 mile-per-hour crash seatbelts and

203
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harness capable of withstanding these

204
00:10:24,360 --> 00:10:21,370
dynamic loads can be comfortable and

205
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light in weight to summarize the

206
00:10:29,160 --> 00:10:26,770
information presented so far has shown

207
00:10:31,440 --> 00:10:29,170
that injuries and crashes result one

208
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from the cockpit collapses and the

209
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occupant is crushed by the airplane

210
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structure to when the seatbelt in

211
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shoulder harness stretch excessively

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under the crash loads and three when the

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occupant is restrained by only a

214
00:10:50,400 --> 00:10:50,020
seatbelt even if the structure remains

215
00:10:52,650 --> 00:10:50,410
in

216
00:10:54,960 --> 00:10:52,660
act both seatbelt and shoulder harness

217
00:10:58,410 --> 00:10:54,970
are necessary in small cockpits if

218
00:11:00,030 --> 00:10:58,420
serious body blows are to be avoided the

219
00:11:01,860 --> 00:11:00,040
information presented here has also

220
00:11:06,540 --> 00:11:01,870
indicated the loads produced in the

221
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restraining harness during a crash even

222
00:11:10,889 --> 00:11:08,170
if the occupant is properly restrained

223
00:11:13,860 --> 00:11:10,899
during a crash he may still be injured

224
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by the deceleration she encounters the

225
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severity of the injury received from a

226
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deceleration depends on the magnitude of

227
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the deceleration the rate at which it

228
00:11:29,129 --> 00:11:24,699
increases commonly called the rate of

229
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onset and the duration of the

230
00:11:33,660 --> 00:11:31,990
deceleration these conclusions were

231
00:11:35,540 --> 00:11:33,670
reached from the work of lieutenant

232
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colonel staff in the report entitled

233
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human exposures to linear deceleration

234
00:11:43,829 --> 00:11:41,740
in this study by staff tests were made

235
00:11:45,629 --> 00:11:43,839
with human beings carefully supported by

236
00:11:48,929 --> 00:11:45,639
specially designed seatbelt shoulder

237
00:11:51,300 --> 00:11:48,939
harness and leg straps under such

238
00:11:53,369 --> 00:11:51,310
conditions the experimenter subjected

239
00:11:56,129 --> 00:11:53,379
himself to a deceleration that had a

240
00:11:59,519 --> 00:11:56,139
maximum of forty seven G's the

241
00:12:03,420 --> 00:11:59,529
deceleration endured 4.2 28 seconds and

242
00:12:06,170 --> 00:12:03,430
had a rate of onset of 735 G's per

243
00:12:08,660 --> 00:12:06,180
second the resulting injuries were minor

244
00:12:13,319 --> 00:12:08,670
when the rate of onset increased from

245
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735 to 1550 G's per second signs of

246
00:12:17,370 --> 00:12:15,970
shock were observed to obtain an

247
00:12:18,689 --> 00:12:17,380
indication of the injuries that may

248
00:12:20,009 --> 00:12:18,699
result from the decelerations

249
00:12:22,499 --> 00:12:20,019
encountered in these experimental

250
00:12:25,050 --> 00:12:22,509
crashes the deceleration zuv the rear

251
00:12:26,639 --> 00:12:25,060
dummies chest were measured these

252
00:12:29,309 --> 00:12:26,649
decelerations had about the same

253
00:12:31,439 --> 00:12:29,319
duration and the magnitudes were very

254
00:12:34,860 --> 00:12:31,449
little higher than those reported by

255
00:12:36,660 --> 00:12:34,870
staff a maximum deceleration of 50 G's

256
00:12:40,079 --> 00:12:36,670
was measured in the rear dummies chest

257
00:12:41,850 --> 00:12:40,089
in the 60 mile-per-hour crash the

258
00:12:46,829 --> 00:12:41,860
maximum full of the 47 mile-per-hour

259
00:12:51,259 --> 00:12:46,839
crash was 40 60 s and the maximum for

260
00:12:53,730 --> 00:12:51,269
the 42 mile-per-hour crash was 32 Gees

261
00:12:56,220 --> 00:12:53,740
from the standpoint of magnitude and

262
00:12:58,110 --> 00:12:56,230
duration these decelerations are within

263
00:13:00,780 --> 00:12:58,120
the tolerable limits established by

264
00:13:02,429 --> 00:13:00,790
steps worked however the rate at which

265
00:13:04,050 --> 00:13:02,439
the deceleration increases in these

266
00:13:07,080 --> 00:13:04,060
light airplane crashes

267
00:13:12,090 --> 00:13:07,090
buried from 2200 jeez per second for the

268
00:13:15,420 --> 00:13:12,100
60 mile-per-hour crash to 950 for the 42

269
00:13:17,370 --> 00:13:15,430
mile-per-hour crash it's expected that

270
00:13:20,400 --> 00:13:17,380
these high rates of onset would cause

271
00:13:22,110 --> 00:13:20,410
momentary unconsciousness it may be

272
00:13:23,790 --> 00:13:22,120
concluded therefore that the

273
00:13:26,430 --> 00:13:23,800
decelerations measured in these crashes

274
00:13:30,990 --> 00:13:26,440
are not large enough to fatally injure

275
00:13:32,610 --> 00:13:31,000
the occupant in the rear seat oddly

276
00:13:34,530 --> 00:13:32,620
enough the deceleration of the occupant

277
00:13:36,870 --> 00:13:34,540
during a crash is often higher than that

278
00:13:38,430 --> 00:13:36,880
of the fuselage floor this effect is

279
00:13:40,560 --> 00:13:38,440
shown in the following motion picture

280
00:13:43,320 --> 00:13:40,570
sequence in which the action is slowed

281
00:13:44,880 --> 00:13:43,330
to about one sixtieth of normal graphs

282
00:13:46,920 --> 00:13:44,890
of the deceleration of the chest and

283
00:13:49,410 --> 00:13:46,930
floor are superimposed over the motion

284
00:13:55,920 --> 00:13:49,420
picture these graphs developed in phase

285
00:13:57,480 --> 00:13:55,930
with the airplanes action notice that

286
00:13:59,520 --> 00:13:57,490
during the period that the seatbelt and

287
00:14:01,640 --> 00:13:59,530
harness stretch the dummy decelerates

288
00:14:04,290 --> 00:14:01,650
less than the fuselage floor under him

289
00:14:06,330 --> 00:14:04,300
during this period the dummy acquires

290
00:14:08,700 --> 00:14:06,340
velocity relative to the local airplane

291
00:14:10,770 --> 00:14:08,710
structure when the seatbelt and harness

292
00:14:12,630 --> 00:14:10,780
stretch is complete the passenger is

293
00:14:15,240 --> 00:14:12,640
decelerated rapidly to the speed of the

294
00:14:17,070 --> 00:14:15,250
airplane this causes the dummy to have

295
00:14:19,500 --> 00:14:17,080
larger peak decelerations than the

296
00:14:21,960 --> 00:14:19,510
fuselage floor the deceleration of the

297
00:14:24,720 --> 00:14:21,970
fuselage floor had a peak of 35 G's

298
00:14:28,080 --> 00:14:24,730
whereas the peak for the chest was 50

299
00:14:30,030 --> 00:14:28,090
G's this increase in the chest

300
00:14:32,610 --> 00:14:30,040
deceleration over that of the fuselage

301
00:14:34,650 --> 00:14:32,620
floor was also found in the 47

302
00:14:37,140 --> 00:14:34,660
mile-per-hour crash when the dummy was

303
00:14:39,000 --> 00:14:37,150
restrained only by a seatbelt this

304
00:14:41,460 --> 00:14:39,010
amplification of peak decelerations

305
00:14:43,260 --> 00:14:41,470
maybe even greater if the seatbelt in

306
00:14:46,140 --> 00:14:43,270
shoulder harness our slack when the

307
00:14:48,180 --> 00:14:46,150
crash occurs the slack and stretch in

308
00:14:50,400 --> 00:14:48,190
these members may cause failure of the

309
00:14:52,610 --> 00:14:50,410
seatbelt and harness as a result of the

310
00:14:55,470 --> 00:14:52,620
high crash deceleration loads produced

311
00:14:57,810 --> 00:14:55,480
the deceleration imposed on the occupant

312
00:15:00,840 --> 00:14:57,820
and his restraints depends on the

313
00:15:02,700 --> 00:15:00,850
deceleration of the fuselage floor the

314
00:15:04,800 --> 00:15:02,710
deceleration of the fuselage floor in

315
00:15:06,930 --> 00:15:04,810
turn depends on the strength of the

316
00:15:09,960 --> 00:15:06,940
airplane structure and the distribution

317
00:15:12,060 --> 00:15:09,970
of the airplane wait in the 47

318
00:15:13,920 --> 00:15:12,070
mile-per-hour crash shown at about 140

319
00:15:15,540 --> 00:15:13,930
eighth of normal speed notice how the

320
00:15:17,460 --> 00:15:15,550
deceleration of the fuselage floor

321
00:15:19,170 --> 00:15:17,470
reaches successive Peaks

322
00:15:20,820 --> 00:15:19,180
every time a main structural element

323
00:15:22,860 --> 00:15:20,830
supports the crash load a peak

324
00:15:24,620 --> 00:15:22,870
deceleration occurs when the loaded

325
00:15:27,090 --> 00:15:24,630
structure breaks the deceleration drops

326
00:15:29,400 --> 00:15:27,100
the maximum deceleration of the cockpit

327
00:15:31,500 --> 00:15:29,410
therefore depends directly on the

328
00:15:33,740 --> 00:15:31,510
strength of the structure as long as the

329
00:15:36,330 --> 00:15:33,750
cockpit has not collapsed completely

330
00:15:38,730 --> 00:15:36,340
this is illustrated by a comparison of

331
00:15:45,090 --> 00:15:38,740
the maximum decelerations measured in

332
00:15:48,300 --> 00:15:45,100
the 60 and 47 mile-per-hour crashes with

333
00:15:50,280 --> 00:15:48,310
those of the 42 mile-per-hour crash the

334
00:15:54,210 --> 00:15:50,290
maximum deceleration in all cases is

335
00:15:57,360 --> 00:15:54,220
about the same ranging between 26 and 33

336
00:15:59,280 --> 00:15:57,370
jeans these decelerations represent the

337
00:16:04,440 --> 00:15:59,290
maximum load that the airplane structure

338
00:16:06,990 --> 00:16:04,450
can support the higher kinetic energy of

339
00:16:08,940 --> 00:16:07,000
the higher speed crash is dissipated by

340
00:16:11,490 --> 00:16:08,950
more extensive crushing of this fuselage

341
00:16:13,170 --> 00:16:11,500
force structure this increase in the

342
00:16:15,300 --> 00:16:13,180
crumpling of the fuselage for structure

343
00:16:21,090 --> 00:16:15,310
increases the time during which the

344
00:16:22,410 --> 00:16:21,100
cockpit decelerations exist the extent

345
00:16:24,330 --> 00:16:22,420
to which the crumpling of the fuselage

346
00:16:26,970 --> 00:16:24,340
force structure reduces the deceleration

347
00:16:28,680 --> 00:16:26,980
applied to the cockpit floor can be seen

348
00:16:30,810 --> 00:16:28,690
by comparing the deceleration of the

349
00:16:34,230 --> 00:16:30,820
engine with that of the fuselage floor

350
00:16:36,180 --> 00:16:34,240
in the 60 mile-per-hour crash notice in

351
00:16:38,010 --> 00:16:36,190
the next motion picture sequence that

352
00:16:40,380 --> 00:16:38,020
the engine deceleration Rises

353
00:16:43,050 --> 00:16:40,390
immediately upon impact whereas the

354
00:16:45,060 --> 00:16:43,060
floor deceleration Rises gradually until

355
00:16:48,270 --> 00:16:45,070
extensive crumpling of the fuselage for

356
00:16:50,340 --> 00:16:48,280
structure has taken place this crumpling

357
00:16:52,980 --> 00:16:50,350
of the fuselage absorbs a considerable

358
00:16:54,510 --> 00:16:52,990
portion of the crash energy when the

359
00:16:56,340 --> 00:16:54,520
force structure has crumpled and the

360
00:16:59,310 --> 00:16:56,350
load is applied directly to the fuselage

361
00:17:05,070 --> 00:16:59,320
floor the engine and floor decelerate at

362
00:17:07,680 --> 00:17:05,080
about the same rate the pig deceleration

363
00:17:12,990 --> 00:17:07,690
of the engine was 62 jeez while the

364
00:17:15,360 --> 00:17:13,000
floor had a peak of only 35 G's for this

365
00:17:17,310 --> 00:17:15,370
reason it's desirable to place as much

366
00:17:19,500 --> 00:17:17,320
of the airplane as possible forward of

367
00:17:22,380 --> 00:17:19,510
the cockpit this arrangement has two

368
00:17:24,240 --> 00:17:22,390
principal advantages first it places

369
00:17:26,460 --> 00:17:24,250
much of the airplane structure in front

370
00:17:30,210 --> 00:17:26,470
of the cockpit to crumple and cushion

371
00:17:31,380 --> 00:17:30,220
the crash flow and second it places much

372
00:17:34,860 --> 00:17:31,390
of the airplane mass

373
00:17:37,140 --> 00:17:34,870
front of the cockpit by reducing the

374
00:17:39,660 --> 00:17:37,150
mass behind the cockpit the load on the

375
00:17:41,610 --> 00:17:39,670
cockpit structure is reduced and failure

376
00:17:45,000 --> 00:17:41,620
of this structure is less likely in a

377
00:17:46,860 --> 00:17:45,010
crash it may be concluded therefore that

378
00:17:49,380 --> 00:17:46,870
the chances of surviving a crash are

379
00:17:51,090 --> 00:17:49,390
better if both the seat belt and the

380
00:17:54,000 --> 00:17:51,100
shoulder harness of proper design are

381
00:17:56,430 --> 00:17:54,010
used the chances of impact survival are

382
00:17:58,710 --> 00:17:56,440
also better if the airplane has much of

383
00:18:01,830 --> 00:17:58,720
its structure and mass ahead of the

384
00:18:04,470 --> 00:18:01,840
cockpit the information presented in

385
00:18:07,710 --> 00:18:04,480
this motion picture is reported in NAC a

386
00:18:09,540 --> 00:18:07,720
technical note 2991 entitled

387
00:18:11,820 --> 00:18:09,550
accelerations and passenger harness