Photo, The Alert 5, F14 Tomcat
moves onto the catapults, the Blast Deflector is lifted up.

This is an F14 Tomcat from VF-114, called the Flying Aardvarks, with engines on full power, without afterburner, sitting on the catapult. 

At Oshkosh 1999, I found another name for the exhaust nozzles is turkey feathers

I need your help! I wish an F14 pilot would send me a story and photo's of his 0009862
0009862ALT="F-14 Tomcat Jet Figther Picture" HSPACE=10 VSPACE=10 BORDER=2 height=197 width=250 align=RIGHT>experience on a carrier.   Send me e-mail at the bottom of this page.

Look at the structure standing up behind this F14 Tomcat. This is a Jet Blast Deflector. It is a part of the deck which is lifted up with hydraulics and prevents the super high speed super hot jet blast from blowing down the deck. The JBD is water cooled to prevent the extreme heat for the exhaust from melting its surface. 

I used to sleep under the JBD of the left front catapult. Once we were past Hawaii we had flight ops almost continuously. These aircraft were pumping out over 40,000 lbs. of thrust less than ten feet above my head. I could hear the hydraulic pump lifting the JBD behind the Jet. 
The engines were turned up to full power for a few seconds, then the catapult launched the aircraft off of the deck. When the catapult shuttle hit the water brake at the end of the deck, the entire ship would shake. 

This wasn't launch an airplane and wait. This was launch one airplane, then another, then another, non-stop, until all of the squadrons were off the deck. When it was time to sleep you would think that this was an annoyance. I can't believe it myself, but it never bothered me. I guess it was just a way of life.

I need your help to make this website grow. If you have any stories or photo's of carrier life or carrier operation, please send them to me at the bottom of this page.

8-16-00 
Subject: F-14 Exhaust Nozzles, jet blast deflector

Hi,
My name is LCDR Andy Loiselle. Here is some information on exhaust nozzles. They work on a basic principle of pressure being  inversely proportional to velocity. As velocity goes down, pressure goes up and vice versa. When the nozzle is open on deck, that is to reduce residual thrust so people behind the jet are not blown over. Once the throttles are brought off the idle stops, the nozzles begin to "pucker" to increase the thrust. When the nozzles pucker, it appears that the hole at the end of the engine is getting smaller. While this is true, this is not what generates additional thrust. When the nozzle closes, there is a section midway through the nozzle that closes even smaller than the exit of the nozzle. As the exhaust gasses get constricted in the nozzle, the pressure goes up as the velocity goes down. When the inside of the nozzle begins to expand again, there is a very substantial pressure drop as the nozzle opens to the athmosphere. This allows a rapid increase in velocity as the exhaust gasses exit the engine.

When afterburners are operated, the nozzle does not have to generate as much of a pressure differential due to the large amount of pressure being generated in the afterburner section. This is why the nozzle is gradually opened as the burners stage.  DLC is direct lift control and is controlled by a thumbwheel on the control stick. It modulates the two inboard spoilers over the wing in order to modulate the amount of lift that the wing is generating. If you are getting high on your approach, you can extend the spoilers and  maybe still get in the wires. Because the F-14 does not have ailerons, it rolls via differential horizontal stabilators and the use of spoilers on the down going wing.

  Hope this helps.

  Andy Loiselle

8-16-00
Re: F-14 Exhaust Nozzles    from the webmaster

 I was also wondering if the exhaust nozzle will change its size according to altitude? 

8-19-00
Re: F-14 Exhaust Nozzles

Hello Jeff, 
The exhaust nozzles do not change size at anything less than military (non-afterburner) power, except at idle, regardless of altitude. There is a change in nozzle programming for afterburners operation as altitude  increases. At very high altitude, the nozzles may only open up 50% or so at  full A/B, while they would be open about 95%or so at sea level. This is due  to the amount of thrust being developed at the different altitudes. The  rated thrust of an engine is always quoted for sea level operation.  Military power at sea level may burn 10,000 pounds (1500 gallons/hour) per  hour per engine, while at 35,000 feet, fuel burn would be more like 4000  pounds/engine. This means that there is less pressure developed in the afterburner section at high altitude, so the nozzle does not open as much. 

Good Luck, 
  Andy Loiselle