Take off by cuiliqing

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									Take off

1. Introduction

       To a new pilot the first true flying experience is the take off. As the airplane
accelerates on the runway, one can not but feels exhilarated. Holding on the yoke until
the instructor says, “Pull back the yoke!” At this moment, with a gentle pull on the yoke,
the nose of the airplane raises and the nose gear breaks up its contact with the ground.
The airplane may shake a little, but, it starts to break away from the bondage of the
gravity. The feeling is a mixture of excitement and fear. The excitement comes from the
fact that finally we started to fly. The fear is due to the unfamiliarity with the face up
position (attitude) not experienced before. Any flight begins with a take off. A good start
will make the experience an enjoyable one.
       While most first time pilot successfully and uneventfully made his/her first take off,
take off can be dangerous. Even some airlines crashed during take off. Why is take off
dangerous? Just think about how is the airplane configured during the take off one will
understand the reason quickly. At take off, the airplane is at its maximum weight; no fuel
has been burnt off yet. The airplane is also at its slowest speed during the entire flight. To
compound the problem, the airplane is very close to the ground. There is not much
margin of error allowed. Any loss of altitude will put the airplane on the ground very
quickly. The airplane is also at the nose high attitude with very large angle of attack1.
Stall, a situation all pilots are scared of, is the result of the wing angle of attack exceeds
around 10 degrees. It does not seem to be hard to exceed this small angle! As you can see
that take off is not something one can take lightly. Oh, by the way, did I mention that
there might be a strong gusty cross wind blowing from the side. The wind gust wants to
blow the upwind wing over (flip over the airplane). Today might also be hot and humid
and we are on a short grass runway with tall trees at both ends of the runway. It seems to
take forever for the airplane to accelerate to the rotation speed (the speed to pull the yoke
back). Now we can see that take off is not as easy and benign as we first thought.
       One must follow the procedure in the Pilot Operating Handbook (POH) carefully in
order to avoid any unfortunately mistakes. In this chapter we will discuss how to make a
good take off. A good take off is defined as a take off that is uneventful, allows the
airplane to climb along the extended runway centerline to the desired altitude at the
desired rate (either best angle of climb2 or best rate of climb3). While discussing the
techniques of a flight, we will also interject with the theories of flight and explain the
phenomena commonly experienced.

2. Proper Take Off Procedures

      Take off procedure depends on the take off situation. First we will discuss ideal
condition when there is no cross wind, at mild climate and low elevation. Generally the
Pilot Operating Handbook provides three take off procedures: normal take off, short field

1
  The angle of attack is the angle between the wing cord line and the related wind (air relative to the travel
of the airplane).
2
  Vx, the speed that allows the airplane to gain most altitude per horizontal distance.
3
  Vy, the speed that allows the airplane to gain most altitude per time unit.


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take off and soft field take off. In order for a pilot to receive his/her certificate, one must
master all three take off procedures. The normal take off procedure assumes the airplane
is taking off from a paved runway with sufficient length. Of course the sufficient length is
a relative term. It is the length long enough for the airplane flown to make normal ground
roll, lift off, climb at best rate of climb and clear the 50 ft obstacle at end of the runway.
The actual length depends on the type of the airplane being flown. A two thousand five
hundred feet is sufficient for a Cessna 152 to make a normal take off roll and climb over
a 50 ft obstacle at end of the runway. However, it is not sufficient for a Boeing 737 jet to
do the same.

       a. Normal Take Off


       b. Short Field Take Off

       c. Soft Field Take Off


3. Cross Winds

4. High Density Altitude

5. Left Turning Tendency




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