
Beginner's
Guide to Propulsion
Forces in a Climb
Answers
 Assuming the
angle of ascent is a constant, find the angle the plane must use to
achieve this height at this distanceto the nearest degree.
The angle should be rounded to 10 degrees.
 a. Find
the thrust for a Boeing 737600 airplane.
Thrust is 22,700 lbs = 100,970 N per
engine. Total thrust is 201,940 N.
b. What is the take off weight of the plane?
Takeoff weight is 145,500 lbs,
or 646,800 N.
c. Use the first equation on the Forces
In A Climb page to find vertical net force.
Use 700,000 N as the lift and 35,000 N as the drag.
L cos 10 + F sin 10  d sin 10  W = ma (vertical)
700,000 cos 10 + 201,940 sin 10  35,000 sin 10  646,800 =
71,554 N = net vertical force ( 689,365
+ 35,066  6,077  646,800 = 71,554 N )
d. Use the second equation to find the horizontal
net force, use lift and drag from part c above.
F cos 10  L sin 10 D cos 10 = ma (horizontal)
201,940 cos 10  700,000 sin 10  35,000 cos 10 = 42,851
N (horizontal)
( 198,872  121,553  34,468 = 42,851 N
)
 Divide your net
force from 2c and 2d by the weight of the airplane to get the vertical
and horizontal acceleration in "g's" (ratioed to gravitational acceleration).
The vertical acceleration = .111
g's
The
horizontal acceleration = .066
g's
Note to
teachers: You may extend this assignment by going to Newton's
Second Law.
