petebuilt Posted September 20, 2012 Share Posted September 20, 2012 I was working in Klamath Falls (Oregon) today. Several OANG F-15's were flying around, about 10 or so. When they circling around, doing their individual approaches to land, I could here a (best I can describe) loud chirping sound, like a bird chirping. It came from each jet as he made the turn to the approach. They were probably at 300-400 feet above me. (I was on top of a Big 5 Sporting Goods building) Does anyone know what that sound would be? Thanks, Pete Brown Quote Link to post Share on other sites
Flush Posted September 30, 2012 Share Posted September 30, 2012 If I was a betting man, I would say that it’s the nozzles opening and closing as the pilot adjusts the throttle for landing. The nozzles are pneumatically driven and make a whistling noise as they cycle positions. Flush Quote Link to post Share on other sites
Ol Crew Dog Posted September 30, 2012 Share Posted September 30, 2012 I was working in Klamath Falls (Oregon) today. Several OANG F-15's were flying around, about 10 or so. When they circling around, doing their individual approaches to land, I could here a (best I can describe) loud chirping sound, like a bird chirping. It came from each jet as he made the turn to the approach. They were probably at 300-400 feet above me. (I was on top of a Big 5 Sporting Goods building) Does anyone know what that sound would be? Thanks, Pete Brown Didn't we go through this same question last week? What you are hearing is the CENC (Convergent Engine Nozzle Controller) cycling through. If the convergent nozzle made this sound time to fix a few things. The convergent nozzle movement is controlled by a primary actuator connected to the CENC in turn connected to secondary actuators by way of a connecting ring which is very smooth and quite when operated. Cheers Dave retired USAF F-15A,B,C,D,E,I,J,and S Crew Chief, Engines, Hydraulics, and Crash Recovery Quote Link to post Share on other sites
geedubelyer Posted September 30, 2012 Share Posted September 30, 2012 Didn't we go through this same question last week? What you are hearing is the CENC (Convergent Engine Nozzle Controller) cycling through. If the convergent nozzle made this sound time to fix a few things. The convergent nozzle movement is controlled by a primary actuator connected to the CENC in turn connected to secondary actuators by way of a connecting ring which is very smooth and quite when operated. Cheers Dave retired USAF F-15A,B,C,D,E,I,J,and S Crew Chief, Engines, Hydraulics, and Crash Recovery Whoa.....deja vu! :blink: Yep..........see >> here << Still the same answer petebuilt ;) Quote Link to post Share on other sites
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