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## Design Challenge Activity If so instructed by your teacher, print out a worksheet page for these problems.

A. In order to understand jet engines, you must understand the concepts of flight and Newton's Laws of Motion. The Fundamental Terms lesson should provide a partial foundation for this brainstorming activity.

B. As you begin the activity, you should first work individually to develop the proposed recommendations. After you have seriously exhausted your efforts, form a team with another student who is seated near you. Compare notes and solutions with your team member, and then combine with another team across the room. (The purpose of the last combination is to increase objectivity.)

C. Aircraft are designed to accomplish a desired mission. The shape, weight, and aerodynamics of the aircraft are all selected to meet the mission requirements. The size of the jet engine is usually chosen to produce enough takeoff thrust to get the aircraft into the air. Companies that build aircraft must also consider the cost and profitability of the planes if they are to stay in business.

Shown below is information on four aircraft that Boeing makes for commercial airlines. In this exercise, you will be working with the hyperlinked information.

Aircraft
Wingspan
Length
Tail Height
Gross Taxi Wt.
Engines & Quantity
Fuel Capacity
777-300
199'11"
242'4"
60'8"
660,000 lbs.
PW 4000 (2)
45,200 gal.
737-400
94'9"
119'7"
36'6"
150,000 lbs.
CFM 56-3 (2)
6,295 gal.
757-300
124'10"
178'7"
44'6"
270,000 lbs.
PW 2000 (2)
11,526 gal.
727
108"
153'2"
34'
191,000 lbs.
JT8D-17R (3)
8,000(est.) gal.

In addition, shown below is a table describing thrust, overall length of the engine, and the fan tip diameters of the engines used on these airplanes today.

Engine
Airplane
Takeoff Thrust
Length of Engine
Fan Tip Diameter
CFM 56 3B-1
737
18,500 lbs.
93"
60"
CFM 56 3B-2
737
22,000 lbs.
93"
60"
CFM 56 3C-1
737
18,500 lbs.
93"
60"
PW 2000
757
38,400-43,734 lbs.
141.4"
78.5"
PW JT8D-17R
727
17,400 lbs.
90 "(est.)
60"(est.)
PW 4000
777-300
86,760-98,000 lbs.
191.7"
112"
RR Trent 800
777-300
92,000-104,000 lbs.
190"(est.)
110"

D. Your problem is as follows:

You are responsible for a fleet of 50 Boeing 777-300s that use PW 4000 and RR Trent 800 turbofan engines. The demand for these new engines is so great that neither Pratt & Whitney nor Rolls-Royce will be able to deliver your new engines for five years. You would like to get your aircraft into service, but you cannot use this type of engine.

Your accountant, Wilson, has located an inventory of excess smaller engines that have been used on other aircraft in your fleet. If you can redesign (or modify) your 777s to accept the smaller engines, you can get the 777s into the air and save your business. The inventory is as follows:

Engines
Inventory (187)
CFM 56 3B-1
25
CFM 56 3B-2
30
CFM 56 3C-1
20
PW 2000
40
PW JT8D-17R
72

For consistency and efficiency of your workers, you are permitted only ONE modification. (By the way, going out of business is not an option.)

1. What is your primary concern or challenge?

2. Why?

3. Which engines would you install on the 777s?

4. Determine the number and models of engines, as well as their physical position on the plane.

5. Any group positioning the engines in unique but fully functional positions will earn a 5% Bonus.

6. Describe any other design alterations and explain why.

7. How many airplanes can you put back in the air?

Related Pages:
Standards
Worksheet
Aerodynamics Activity Index
Aerodynamics Index

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