Airspeed
Activity
If so instructed by your teacher, print out a worksheet page
for these problems.
Beginner's Guide
to Aerodynamics is a "textbook" of information prepared at NASA
Glenn Research Center to help you better understand how airplanes
work. Click Beginner's Guide
Index to access the list of slides. Open the slide called
Relative Velocities
(with text) and read the explanation on how relative velocities
are used to calculate airspeed required for aircraft launch.
In airport takeoff
situations, the ground speed of the aircraft and the wind speed
are the only factors in airspeed. The U.S. Navy has an additional
variable. Its airports (aircraft carriers) move on the ocean at
speeds that can be in excess of 35 mph. Airspeed in this unique
situation is a sum of the ship's speed through the water, wind speed,
and the speed of the aircraft over the deck of the ship provided
by the ship's catapult.
A catapult
is like a huge rubber band and is used to propel an aircraft to
higher speeds over a short distance in a few seconds. For more information
on aircraft carriers and catapults, click on
Aircraft
Carriers (http://en.wikipedia.org/wiki/Aircraft_catapult).
Assume that
a typical catapult can propel an aircraft from 0 to 150 mph in 2
seconds. The aircraft carrier problem is pictured graphically in
the following illustration. (Note the airspeed equation at
the bottom.)
You are the Captain
of the Aircraft Carrier USS Enterprise (CVN-65). Assume that the required
airspeed for takeoff of an F-14 is 170 mph. Using the airspeed equation
and information provided, complete the following table and answer
the questions that follow. Assume that a positive wind velocity is
in the direction of travel of the ship.
-
-
Catapult
Speed (Vc) mph
|
Ship
Speed
(Vs) mph
|
Wind
Speed
(Vw) mph
|
Airspeed
|
Go/No
Go
(>170 mph)
|
150
|
20
|
-10
|
|
|
150
|
20
|
10
|
|
|
150
|
30
|
-30
|
|
|
150
|
0
|
20
|
|
|
-
Airspeed
= Ship Speed (Vs) + Catapult Speed (Vc) - Wind Speed (Vw)
Questions
- With no wind,
what should the speed of the ship be to launch an F-14?
Vs = ____________________
- On launch
any aviator wants to maximize lift. What would you do as Captain
of the ship any time you launch aircraft?
- Are wind
direction and ship speed factors in landing as well?
- Convert the
completed table above to metric units (to the nearest kph).
-
Catapult
Speed (Vc) mph
|
Ship
Speed
(Vs) mph
|
Wind
Speed
(Vw) mph
|
Airspeed
|
Go/No
Go
(>274 km/h)
|
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