Intro
Worksheet
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Beginner's
Guide to Propulsion
Thrust to Weight Ratio
Activity
If so instructed by your teacher, print out a worksheet page for these
problems. Before you begin to answer the questions on the worksheet:
- The thrust
to weight ratio is an efficiency factor for total aircraft propulsion.
An aircraft with a high thrust to weight ratio has high acceleration.
It has a high value of excess thrust which results in a high rate
of climb.
- By searching
various aircraft and engine sites on the Internet (examples: Boeing,
Pratt &
Whitney, General
Electric, and Engines),
fill in the table on the worksheet page with information from at least
four different aircraft.
- Then using that
information, calculate the thrust to weight ratios and decide which
aircraft has the highest ratios.
- The name of the
aircraft, number of engines, engine type, thrust per engine, engine
mass, and airplane mass can be find on the Internet. You must perform
calculations, in particular, multiplication and division, to complete
the table. Some hints are shown below the table.
Thrust to Weight
Ratio
Name
of Aircraft
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Number
of Engines
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Engine
Type
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Name
of Engine
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Thrust
per Engine in kN
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Total
Thrust
Thrust
per engine x number of engines
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Name
of Aircraft
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Engine
Mass in kg
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Total
Engine Weight in kN
Engine
mass x number of engines x 9.8 m/s2
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Airplane
Mass in kg
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Airplane
Weight in kN
Mass
x 9.8 m/s2
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Name
of Aircraft
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Thrust
to Engine Weight Ratio
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Thrust
to Airplane Weight Ratio
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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:
- What are the
four forces that act on an aircraft?
- What are three
things that determine the weight of an airplane?
- What are two
things that determine the thrust of an airplane?
- A high thrust
to weight ratio means that the aircraft will have high _____________and
a high _______________.
- If the thrust
to weight ratio is greater than 1, this means the aircraft will be
able to ______________________________.
- Which of your
four aircraft from the table above had the greatest thrust to engine
weight ratio?
- Which of your
four aircraft had the greatest thrust to aircraft weight ratio?
- Was your answer
the same for questions 6 and 7? Why or why not?
- Explain what
a ratio is in your own words.
- Write a few sentences
summarizing this activity and what you learned from it.
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