Visiting the Air National Guard
183rd Fighter Squadron, 6-12-2000
Springfield, IL.

The jets were ready to take off. 

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 learn.