engine & exhaust

There were 2 different engines used by the YF-23 as part of the Dem/Val phase. PAV-1 used Pratt & Whitney YF119's and PAV-2 used GE YF120's. For the first time time ever we present clear colour pictures of the GE YF120 as fitted out for the YF-23. We are the first aviation-oriented publication to do this. The nozzle system employed on the YF-23 was unique, with a single paddle system providing adjustment to latent air pressure from above. There was no similarly shaped paddle at the bottom, just a fixed straight surface which met the start of the efflux trough. The nozzle for the GE YF120 was slightly wider than the version built for the P&W YF119. New pics of the GE YF120 can be found at Scott Lowther's Unwanted Blog. He has won another award for this effort.


September 2011: the clearest shot yet published of the GE YF120 as fitted to YF-23 PAV-2. This engine was briefly put on display in the R&D Hangar at the USAF National Museum in Ohio, next to the AFTI F-16 and P&W powered PAV-1. You saw it first on YF-23.net.

This is a Youtube video uploaded by Kenrushia taken at an airshow held at Pease AFB in 2010. Even though the exhibit signs state the engine is a production variant for the F-22, it is in fact a complete Pratt & Whitney YF119 engine as configured for YF-23 PAV-1. Kenrushia shows every aspect of the engine in closeup detail. It is not clear whether this engine was actually pulled from PAV-1 or was an extra test engine. Thanks to Flateric for posting this video at the Secret Projects forum.


The engine bay longerons were spaced to be able to accomodate either engine with only slight changes to the positioning of mounting lugs and couplings. The bays were lined with heat reflective material. The troughs used for the GE YF120 on PAV-2 were slightly wider than those for the P&W YF119 on PAV-1. The nozzle shroud assembly was different as well. PAV-1 had a shroud that hinged downward with the paddle whereas PAV-2 had a fixed shroud covering the paddle. The Lamiloy tiles used in the exhaust trough had exactly the same matrix pattern on both PAV's except that the outer row on PAV-2 was slightly wider. The angle of the trough sidewalls was 90; there was no attempt incorporate stealthy angles. The tiles lining the troughs were not shaped for stealth: they had 90 corners. Some of the tiles on the trough walls were angled but this was merely to accomodate the slope of the nacelle. Air was bled from the engines and passed through the structure of the troughs to cool them. This air exited through a series of tiny perforations just underneath the trailing edge of the troughs. PolymerStew has won an award for the photograph he took included in this section.


PolymerStew's rendition of the exhaust trough on PAV-1 at the National Air Force Museum after its return to pristine condition.

Last updated May 2012.

free analytics for godaddy
Northrop YF-23 ATF engine bay walkaround YF-23 jet fighter exhaust trough walkaround Northrop McDonnell Douglas YF-23 ATF exhaust nozzle walkaround YF-23 Advanced Tactical Fighter jet engine walkaround YF-23 Black Widow II engine bay walkaround YF-23 Grey Ghost jet trough walkaround YF-23 prototype exhaust trench walkaround YF-23 jet walkaround stealth fighter YF-23 details YF-23 close-up shots YF-23 interior photos General Electric YF120 jet engine GE YF120 jet engine GE YF 120 ATF engine GE YF120 turbofan Pratt & Whitney YF119 jet engine P&W YF119 turbojet engine P&W YF 119 turbofan engine Pratt & Whitney ATF engine GE F120 GE F-120 P&W F119 P&W F-119
Prose, illustrations, & website design 2008 YF-23.net except where noted. All rights reserved under the Berne Convention. Copyright should be respected. Seek the permission of the copyright holder before duplicating any artwork or text. Commercial trademarks and company logos are the property of their respective owners, and are only shown here as an academic reference. Reference sources are quoted when known. Information here is collected in many cases from a variety of second hand sources and is not guaranteed to be factual or accurate, and may be subject to error. Please contact the webmaster if you do discover an error or you are the Copyright Holder of specific content and object to its inclusion on this site. We apologize for any site availability difficulties you may encounter. This site is hosted on a 3rd party server; consequently we have no control over, nor can we guarantee, site availability at any particular time.