Beginner's
Guide to Aeronautics
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.)
E. Answer
the following questions on your worksheet:
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?