Visiting the Air National
183rd Fighter Squadron, 6-12-2000
The jets were ready to take off.
Click Here you could see how the variable exhaust nozzles of these F-16 's
really worked. The pilots call them turkey feathers but they call
the birds Falcons. I guess that the Air Force doesn't want to say
that their pilots are flying a bunch of turkeys. Just joking.
The kids watched how these exhaust nozzles changed size to compensate
for thrust as power is added and after the afterburner is turned on.
They have already seen this when we watched movies on the previous two
days. When the planes are at a low power setting the nozzle is full
open. When the engines go to full power, with no afterburner, the
nozzles are at the smallest position. when afterburner is added the
nozzles are again full open.
I believe the size of the nozzles are also changed with changes in altitude.
At higher altitudes the outside air pressure is changed modifying the efficiency
of the exhaust nozzle. A higher altitude requires a longer narrower
exhaust nozzle where lower altitudes require shorter wider nozzles to main
maximum efficiency. This is one reason that NASA rockets use different
stages on their rockets. In this high power environment a little
change in efficiency means a big change in power.
During the movies and at this event I explained this "turkey feather"
operation to the kids. Did they understand what they were seeing?
Let's look at it this way, in advertisement it takes three times before
a person sees an ad and five times before they understand it. Spaced
repetition is the key. If they didn't understand it this time, they
eventually will. Remember, they're only kids and there is a lot to