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Center of Gravity Activity
If so instructed by your teacher, print out a worksheet page for these problems.


Image Representing "Deterniming Center of Gravity - cg


The supply company you work for has just purchased a DC 8-62 cargo transport airplane. You will find the specifications for the new company "toy" below. The company has decided to promote you to ground crew supervisor. You are responsible for loading the DC 8-62 so that the center of gravity of the airplane is maintained at 75 feet ( 22.9 meters).

  1. For the first flight, the cargo airplane is loaded with 2 Igloo cargo shells. The first fiberglass shell contains 4,550 lbs of cargo and is located 40 feet from the reference point. The second aluminum shell contains 7,000 lbs of cargo and is located 110 feet from the reference point. The empty mass (see specifications) is located 75 feet from the reference point. Calculate the center of gravity of your aircraft. (HINT: Don't forget to add in the weight of the Igloo shell to the mass of the cargo.)

     

  2. The second flight is loaded with 2 aluminum Igloo cargo shells each containing 9,590 lbs. Your ground crew has placed one container at 120 ft. from the reference point and the other at 90 ft. from the reference point. The empty mass is still located at 75 ft. Calculate the center of gravity of your aircraft . (HINT: Don't forget to add in the weight of the Igloo shell to the mass of the cargo.)

     

  3. Did your first flight meet your required center of gravity specifications? If you answered no, go to Question 5.

     

  4. Did your second flight meet your required center of gravity specifications? If you answered no, go to Question 5.

     

  5. What correction would the pilot of the airplane have to make during flight to fly the airplane as it is loaded? Where would you move your cargo shells to get the center of gravity to equal the required 75 ft.? 
Diagram of DC 8 showing cargo holds
Forward Belly (bulk) - 800 cu. ft.
Aft Belly (bulk) - 815 cu. ft.
Main Cargo Door (A)- 85" high by 140" wide
Forward Belly Door (B) - 36" high by 44" wide
Aft Belly Door (C) - 36" high by 44" wide
Payload maximum - 90,000 lbs.
Empty mass - 136,600 lbs
Main deck cargo volume (containerized) - 6,160 cu. ft.
[thirteen (13) - 88" x 125" containers or pallets]

 
Type A-3 container
Emery Worldwide aircraft are units loaded utilizing Type A-3 containers and pallets. The
Igloo illustrated, is an enclosed fiberglass or aluminum shell, open on one side and closed
after loading with a fabric cover and straps. Pallets are essentially the same size as the
Igloo, but without the permanent shell. Freight loaded on pallets is restrained with nets.
 
Inside dimensions - 121" long, 84" wide, 76" high
Pallet dimensions - 88" x 125"
Volume capacity - 450 cu. ft.
Maximum gross weight - 10,500 lbs.
Approximate tare weights: 410 lbs. - Aluminum shell; 520 lbs. - Fiberglass shell
 
 

Related Pages:
Standards
Worksheet
Lesson Index
Aerodynamics Index

 

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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Wed, Mar 17 03:09:50 PM EDT 2010

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