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Beginner's Guide to Propulsion
Thrust to Weight Ratio
Answers



Note: Since students are researching their own data on various sites on the Internet, their figures in their table may vary. Answers below are just four examples that were found. If you want to narrow their search options and the amount of time needed, give them the name of the aircraft to start. All information below was found at the Boeing, Pratt & Whitney, or PilotPortal sites.


Thrust to Weight Ratio

 
Name of Aircraft
Number of Engines
Engine Type
Boeing 747 - 400
4
GE CF680C1
Boeing F15
2
PW F100-229
Boeing 737 -300
2
CFM 563B1
Boeing F18
2
F404 GE 402

Name of Aircraft
Thrust Per Engine in kN
Total Thrust

Thrust per engine x engines

Boeing 747-400
252
1008
Boeing F15
66.7
133.4
Boeing 737-300
88.9
177.8
Boeing F18
47.2
94.4

Name of Aircraft
Engine Mass in kg
Total Engine Weight in kN

Engine mass x engines x 9.8 m/s2

Airplane Mass in kg
Airplane Weight in kN

Mass x 9.8 m/s2

Boeing 747-400
4058
159.1
379890
3722.9
Boeing F15
1370
26.9
20411
200
Boeing 737-300
1940
38
59645
584.5
Boeing F18
908
17.8
25401
248.9

Name of Aircraft
Thrust to Engine Weight Ratio
Thrust to Airplane Weight Ratio
Boeing 747-400
6.3
0.27
Boeing F15
4.9
0.67
Boeing 737-300
4.7
0.30
Boeing F18
5.3
0.38

Note: Weight (in Newtons) is equal to mass times the gravitational acceleration rate of 9.8 m/s2.

Note: Remember that kN is simply N divided by 1000.

Note: For Airplane Weight, if more than one value is given, find and use the average of the values. Recall that to find an average, simply add up the values given and divide by the number of values.


Answer the following questions:

  1. What are the four forces that act on an aircraft?
    Lift, weight, thrust, and drag
  2. What are three things that determine the weight of an airplane?
    Size, materials used in construction, payload, and fuel
  3. What are two things that determine the thrust of an airplane?
    Size and type of propulsion system, throttle setting selected by pilot
  4. A high thrust to weight ratio means that the aircraft will have high acceleration and thrust and a high rate of climb.
  5. If the thrust to weight ratio is greater than 1, this means the aircraft will be able to accelerate vertically.
  6. Which of your four aircraft above had the greatest thrust to engine weight ratio?
    Answers will vary according to table above.
  7. Which of your four aircraft had the greatest thrust to aircraft weight ratio?
    Answers will vary according to table above.
  8. Was your answer the same for questions 6 and 7? Why or why not?
    Answers will vary according to table above and answers to questions 6 and 7.
  9. Explain what a ratio is in your own words.
    A ratio is a comparison of two numbers often expressed as a quotient.
  10. Write a few sentences summarizing this activity and what you learned from it.
    Answers will vary according to age and ability of students.

 


Related Pages:
Standards
Activity
Worksheet
Propulsion Activity Index
Propulsion Index

 

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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Thu, Jun 12 04:39:28 PM EDT 2014

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