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fighterfan12
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 Posted: Mar 16, 2012 - 07:15 PM
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Newbie
Joined: Mar 16, 2012 - 07:08 PM
Posts: 1
Location: Fresno
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| We live near Hammer Field Air National Guard base in Fresno. Daily our F-16's are overhead and provide regular thrills. Frequently we hear a high-pitched whistle sound while they are in-flight, directly above us, and it lasts for about a second. It is not a one-pitched sound but starts at a high pitch and climbs - almost a "whoop" but not low enough to be called one - and it's quite noticeable. Can't seem to nail it down to acceleration or deceleration but appears to happen when cruising. Any ideas? |
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Sponsor
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 Posted: May 24, 2013 - 11:54 PM
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F-16.net Sponsor
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m582
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Posted: Mar 16, 2012 - 08:38 PM
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Newbie
Joined: Mar 16, 2012 - 08:36 PM
Posts: 18
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That would be the Convergent Exhaust Nozzle Control. It's an airmotor to adjust the nozzle on the Pratt & Whitney F100 engine. When it moves the nozzle, it make a quite loud noise like you described. It runs on compressed air from the high pressure compressor of the engine (13th stage).
Check the video below, it's an F-15 but it has the same engine. Around 0:16 in the video.
http://www.youtube.com/watch?v=lie5Y4IRpcg |
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That_Engine_Guy
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Posted: Mar 17, 2012 - 12:31 AM
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Elite 2K
Joined: Dec 14, 2005 - 05:03 AM
Posts: 2198
Location: Under the engine somewhere.
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Confirmed
That would be the F100's Convergent Exhaust Nozzle Control or CENC.
The CENC is air driven from high-pressure bleed air that comes from the 13th stage of the compressor. This supply air runs through an air-motor within the CENC and is exhausted through a port in the bottom of the engine bays directly below the CENC. The CENC is located on the aft-fan duct just ahead of the flange where the augmentor duct/nozzle module attaches to the motor.
Whenever the nozzle opens/closes; IE- throttle movements; you will hear WHIRRRRRP noise of the air running through the motor and pouring out the exhaust.
This 'screech' is partly how the Eagle first got it's name.
Ref: http://www.youtube.com/watch?v=tfNeAr8ix10 (1:25-on in the video)
This is to test full open/close or close/open (341 revolutions for the CENC & nozzle actuators) At full speed the nozzle can open/close in about a second. (faster than in the video) When performing a taxi, you will hear the CENCs whenever the pilot throttles up/back to gain/loose speed.
Pratt & Whitney F100 powered Vipers and Eagles make the same sound. GE Vipers do not, their nozzle actuation system is hydraulic.
Every F100 has; YF100-PW-100 through the newest F100-PW-229EEP
Keep 'em flyin' 
TEG
See also:
http://f-16.net/f-16_forum_viewtopic-t- ... -cenc.html (Photos in this link)
http://f-16.net/f-16_forum_viewtopic-t- ... -cenc.html
http://f-16.net/f-16_forum_viewtopic-t- ... -cenc.html |
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[Airplanes are] near perfect, all they lack is the ability to forgive.
β Richard Collins
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vcq09
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Posted: Mar 17, 2012 - 12:44 AM
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Enthusiast
Joined: Jun 10, 2010 - 02:44 AM
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I also live near an ANG base and have F-16s flying sorties pretty much every day, but I've never heard that sound before since we're flying F-16C/D Block 30E. Very cool! I've never met a Viper sound I didn't love  |
Last edited by vcq09 on Mar 17, 2012 - 04:31 AM; edited 1 time in total
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That_Engine_Guy
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Posted: Mar 17, 2012 - 02:33 AM
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Elite 2K
Joined: Dec 14, 2005 - 05:03 AM
Posts: 2198
Location: Under the engine somewhere.
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vcq09 wrote:
I also live near an ANG base and have F-16s flying sorties pretty much every day, but I've never heard that sound before since we're flying F-16C/D Block 30E (I think those are the bigmouth GE F110 engines, right??). Very cool! I've never met a Viper sound I didn't love
If the block # ends with a Zero, it's a GE
If the block # ends with a Two, it's a PW
What city VCQ?
 TEG |
_________________
[Airplanes are] near perfect, all they lack is the ability to forgive.
β Richard Collins
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vcq09
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Posted: Mar 17, 2012 - 04:29 AM
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Enthusiast
Joined: Jun 10, 2010 - 02:44 AM
Posts: 44
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Last edited by vcq09 on Mar 17, 2012 - 04:33 AM; edited 2 times in total
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VarkVet
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Posted: Mar 17, 2012 - 04:32 AM
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Joined: Oct 30, 2006 - 04:31 AM
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That_Engine_Guy wrote:
vcq09 wrote:
I also live near an ANG base and have F-16s flying sorties pretty much every day, but I've never heard that sound before since we're flying F-16C/D Block 30E (I think those are the bigmouth GE F110 engines, right??). Very cool! I've never met a Viper sound I didn't love
If the block # ends with a Zero, it's a GE
If the block # ends with a Two, it's a PW
What city VCQ?
TEG
Except for this one 
http://www.f-16.net/aircraft-database/F ... file/1450/ |
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My eyes have seen the glory of the Lord and the esthetics of the Flightline
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m582
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Posted: Mar 17, 2012 - 11:54 AM
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Joined: Mar 16, 2012 - 08:36 PM
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That_Engine_Guy wrote:
vcq09 wrote:
I also live near an ANG base and have F-16s flying sorties pretty much every day, but I've never heard that sound before since we're flying F-16C/D Block 30E (I think those are the bigmouth GE F110 engines, right??). Very cool! I've never met a Viper sound I didn't love
If the block # ends with a Zero, it's a GE
If the block # ends with a Two, it's a PW
What city VCQ?
TEG
That's correct when you're talking about F-16C/D's only.
Otherwise:
If it's a Block 1, 5, 10, 15, 20 or 25, it's also a PW
But except for the one that VarkVet mentioned.  |
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fiskerwad
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Posted: Mar 17, 2012 - 12:17 PM
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Forum Veteran
Joined: Nov 13, 2004 - 07:43 PM
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m582
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Posted: Mar 17, 2012 - 12:23 PM
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Joined: Mar 16, 2012 - 08:36 PM
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fiskerwad wrote:
Yes, that one had a J79 for a while. But it was a FSD aircraft and it didn't have a Block number. 
75-0752 |
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That_Engine_Guy
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Posted: Mar 17, 2012 - 07:36 PM
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Elite 2K
Joined: Dec 14, 2005 - 05:03 AM
Posts: 2198
Location: Under the engine somewhere.
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m582 wrote:
That_Engine_Guy wrote:
If the block # ends with a Zero, it's a GE
If the block # ends with a Two, it's a PW
What city VCQ?
TEG
That's correct when you're talking about F-16C/D's only.
Otherwise:
If it's a Block 1, 5, 10, 15, 20 or 25, it's also a PW
But except for the one that VarkVet mentioned.
Since VCQ mentioned it was an ANG Viper over the US, it should be a GIVEN that it's not anything lower than a Block 30/32. All the Block 25s and below have been removed from combat service.
So unless you're at a training, testing, or experimental location you should see any Block 25s flying around.
There was a large-mouth Viper with a PW for a while too if you want to split hairs, but he wouldn't have seen it flying around the pattern at any ANG facility.
That was the VISTA bird. 86-0048
http://f-16.net/aircraft-database/F-16/ ... file/1951/
Keep 'em flyin'
TEG |
_________________
[Airplanes are] near perfect, all they lack is the ability to forgive.
β Richard Collins
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m582
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Posted: Mar 17, 2012 - 08:12 PM
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Newbie
Joined: Mar 16, 2012 - 08:36 PM
Posts: 18
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That_Engine_Guy wrote:
Since VCQ mentioned it was an ANG Viper over the US, it should be a GIVEN that it's not anything lower than a Block 30/32. All the Block 25s and below have been removed from combat service.
So unless you're at a training, testing, or experimental location you should see any Block 25s flying around.
There was a large-mouth Viper with a PW for a while too if you want to split hairs, but he wouldn't have seen it flying around the pattern at any ANG facility.
That was the VISTA bird. 86-0048
http://f-16.net/aircraft-database/F-16/ ... file/1951/
Keep 'em flyin'
TEG
Sorry, I wasn't aware you were talking ANG units only. And I mean no offence but the 195th is still flying Block 25s. Besides ANG units, at least the 62nd. |
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That_Engine_Guy
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Posted: Mar 21, 2012 - 12:46 AM
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Elite 2K
Joined: Dec 14, 2005 - 05:03 AM
Posts: 2198
Location: Under the engine somewhere.
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m582 wrote:
That_Engine_Guy wrote:
So unless you're at a training, testing, or experimental location you should see any Block 25s flying around.~TEG
Sorry, I wasn't aware you were talking ANG units only. And I mean no offence but the 195th is still flying Block 25s. Besides ANG units, at least the 62nd.
Realize that M582, let me highlight my post. The portion directed at the 195th and 62nd.
Details my boys; the devil is in the details, and attention to the same....
TEG |
_________________
[Airplanes are] near perfect, all they lack is the ability to forgive.
β Richard Collins
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