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9/22/2017 12:11:25 AM
Posted: 3/17/2006 5:48:09 PM EDT
What is the name of and purpose for the forward wing extension.

I'm referring to the wing-like section that extends from the wings to the cockpit area on either side of the aircraft. The F-16 and other aircraft have similar extensions.

Are they lift generating? Do they focus air flow into the intake?

I've always wondered what they heck they did.

TIA,

Corey
Link Posted: 3/17/2006 5:48:42 PM EDT
Link Posted: 3/17/2006 5:49:21 PM EDT
LERX=Leading Edge Root Extensions.

They have somethign to do with keeping airflow over the wings during high-AOA flying.
Link Posted: 3/17/2006 5:50:09 PM EDT
Link Posted: 3/17/2006 5:50:25 PM EDT
Link Posted: 3/17/2006 5:51:58 PM EDT

Originally Posted By Tomislav:
LERX=Leading Edge Root Extensions.

They have somethign to do with keeping airflow over the wings during high-AOA flying.



it allows the F-18 to fly at a 45 degree angle if need be.

Link Posted: 3/17/2006 5:53:26 PM EDT
Link Posted: 3/17/2006 6:02:04 PM EDT
Added trivia:

The LERX on the MiG-29 have intake slats on top, allowing the pilot to close the main air intakes and open the top intakes, to allow the Fulcrum to takeoff on debris-ridden runways without worrying about foreign object damage.

Link Posted: 3/17/2006 6:03:24 PM EDT

Originally Posted By vito113:
LERX

The wing was provided with a leading edge root extension (LERX) that tapered into the fuselage on a level with the cockpit. The LERX made it possible to achieve post-stall maneuvering capabilities at angles of attack exceeding 30 degrees and later even 40 degrees. At high angles of attack the LERX added about 50 percent to the lift provided by the basic wing. Extending the LERX ahead of the engine inlets had the additional effect of guiding the airflow smoothly into the inlets and presented the engines with a full flow of relatively undisturbed air at high angles of attack, helping to prevent engine flameouts. In addition, a long axial slot was cut into each LERX adjacent to the fuselage ahead of the intakes, preventing a buildup of air ahead of the inlet while in supersonic flight. At low-speed and high angles of attack, these slots provided an escape for boundary-layer air which scrubbed across the fuselage ahead of the inlet. In 1968, the LERX were further enlarged, the forward portions continuing ahead as strakes almost to the nose.

The engines were fed by long ducts which admitted air from semi-circular inlets. These inlets originally were provided with a movable half-cone centerbody ahead of the wing. However, by 1971 it was concluded that Mach 2 performance was not all that important a design objective, and these conical centerbodies were eliminated. At about the same time, the inlets were made shorter and brought back under the LERX. That made the large LERX look a lot like the head of a cobra, so much so in fact that Cobra became the Northrop name for the P-530. The inlets were further refined throughout 1971-71, the final shape selected being a canted oval shape with a fixed, slightly-rounded edge, with the top located 4 inches below the underside of the LERX. The inlets were separated from the fuselage by a large rectangular splitter plate.

http://home.att.net/~jbaugher4/f17.html



No one calls them a "LERX." We call them a LEX: simply, "leading edge extension." LERX just sounds too much like that guy from the adams family.

They provide a lot of lift and significantly increase slow-speed, high AOA flying.
Matt
Link Posted: 3/17/2006 6:08:12 PM EDT
Wow! I'm impressed.

Thanks for the info everyone!

Corey
Link Posted: 3/17/2006 6:13:05 PM EDT
IBTFSBBBG

­



(In Before The F-14 Should Be Brought Back Guys)
Link Posted: 3/17/2006 6:18:44 PM EDT
thanks, vito
you really know this stuff inside out
Link Posted: 3/17/2006 6:21:04 PM EDT

Originally Posted By Tomislav:
Added trivia:

The LERX on the MiG-29 have intake slats on top, allowing the pilot to close the main air intakes and open the top intakes, to allow the Fulcrum to takeoff on debris-ridden runways without worrying about foreign object damage.

img56.imageshack.us/img56/2246/mig2946fy.jpg



Those Ruskie bastards are clever
Link Posted: 3/17/2006 6:21:08 PM EDT
Link Posted: 3/17/2006 6:22:48 PM EDT
[Last Edit: 3/17/2006 6:24:15 PM EDT by KA3B]

Originally Posted By FMD:
(In Before The F-14 Should Be Brought Back Guys)



They had glove vanes (F-14A did anyways).

Link Posted: 3/17/2006 6:31:20 PM EDT
Link Posted: 3/17/2006 6:31:58 PM EDT

Originally Posted By vito113:
More LEX's…

www.suchoj.com/ab1953/Su-27/images/Su-27_14.jpg

Many aerospace engineers consider this one of the most aerodynamically perfect aircraft in the sky



Add Western avionics and engines to it, and it would be amazing. As it is, you have to deal with those less-than-ideal Lyulkas.
Link Posted: 3/17/2006 6:42:52 PM EDT
At high angles of attack, the airflow will separate from the wing, reducing lift to the point of stall. If you can create turbulance, it gives the air enough energy that it won't separate. This is often called energizing or turbulating the boundary layer. So the strake or LEX turbulates the boundary layer near the wing root, giving it enough energy to prevent separation/stall at high angles of attack.

At least that's how I understand it. It's like a really big vortex generator.
Link Posted: 3/17/2006 6:43:58 PM EDT
Link Posted: 3/17/2006 6:50:14 PM EDT

Originally Posted By Tomislav:

Originally Posted By vito113:
More LEX's…

www.suchoj.com/ab1953/Su-27/images/Su-27_14.jpg

Many aerospace engineers consider this one of the most aerodynamically perfect aircraft in the sky



Add Western avionics and engines to it, and it would be amazing. As it is, you have to deal with those less-than-ideal Lyulkas.



Do NOT underestimate the capabilities of the on board radar and EW system. The MMI may not be up to western standards but I can assure you that the electronics combat suite is exceptionally good, which is in keeping with stuff the Soviets had decades ago. They are very good at EW "stuff".

I have no info on the engines. I suspect that with the latest US engines, and up to date cockpit avionics, they would be the finest fighters in the entire world.
Link Posted: 3/17/2006 6:57:24 PM EDT
Link Posted: 3/17/2006 7:34:37 PM EDT

Originally Posted By LWilde:

Originally Posted By Tomislav:

Originally Posted By vito113:
More LEX's…

www.suchoj.com/ab1953/Su-27/images/Su-27_14.jpg

Many aerospace engineers consider this one of the most aerodynamically perfect aircraft in the sky



Add Western avionics and engines to it, and it would be amazing. As it is, you have to deal with those less-than-ideal Lyulkas.



Do NOT underestimate the capabilities of the on board radar and EW system. The MMI may not be up to western standards but I can assure you that the electronics combat suite is exceptionally good, which is in keeping with stuff the Soviets had decades ago. They are very good at EW "stuff".

I have no info on the engines. I suspect that with the latest US engines, and up to date cockpit avionics, they would be the finest fighters in the entire world.



I don't doubt the theoretical quality of Ivan's electronics. The problem enters with quality control on the assembly line; Give Russian designers access to Western manufacturing, and the results would be very interesting.
Link Posted: 3/17/2006 7:43:39 PM EDT

Originally Posted By Tomislav:

Originally Posted By LWilde:

Originally Posted By Tomislav:

Originally Posted By vito113:
More LEX's…

www.suchoj.com/ab1953/Su-27/images/Su-27_14.jpg

Many aerospace engineers consider this one of the most aerodynamically perfect aircraft in the sky



Add Western avionics and engines to it, and it would be amazing. As it is, you have to deal with those less-than-ideal Lyulkas.



Do NOT underestimate the capabilities of the on board radar and EW system. The MMI may not be up to western standards but I can assure you that the electronics combat suite is exceptionally good, which is in keeping with stuff the Soviets had decades ago. They are very good at EW "stuff".

I have no info on the engines. I suspect that with the latest US engines, and up to date cockpit avionics, they would be the finest fighters in the entire world.



I don't doubt the theoretical quality of Ivan's electronics. The problem enters with quality control on the assembly line; Give Russian designers access to Western manufacturing, and the results would be very interesting.



+1. Everything that I have heard about Russian quality control has been negative. One of the main problems is that pannels almost never seem to fit the way that they are supposed to, and I have never seen a Russian aircraft that looked like it was well maintained. That is not to say that they do not exist, just that I have yet to see any. The Russkies do have some pretty neat ideas, many of which the US should consider equiping our aircraft with (the helmet mounted IR missile sight comes to mind).
Link Posted: 3/17/2006 7:47:47 PM EDT

Originally Posted By SkyCatII:

+1. Everything that I have heard about Russian quality control has been negative. One of the main problems is that pannels almost never seem to fit the way that they are supposed to, and I have never seen a Russian aircraft that looked like it was well maintained. That is not to say that they do not exist, just that I have yet to see any. The Russkies do have some pretty neat ideas, many of which the US should consider equiping our aircraft with (the helmet mounted IR missile sight comes to mind).



google AIM-9x
Matt
Link Posted: 3/17/2006 8:26:20 PM EDT

Originally Posted By valheru21:

Originally Posted By vito113:
LERX

The wing was provided with a leading edge root extension (LERX) that tapered into the fuselage on a level with the cockpit. The LERX made it possible to achieve post-stall maneuvering capabilities at angles of attack exceeding 30 degrees and later even 40 degrees. At high angles of attack the LERX added about 50 percent to the lift provided by the basic wing. Extending the LERX ahead of the engine inlets had the additional effect of guiding the airflow smoothly into the inlets and presented the engines with a full flow of relatively undisturbed air at high angles of attack, helping to prevent engine flameouts. In addition, a long axial slot was cut into each LERX adjacent to the fuselage ahead of the intakes, preventing a buildup of air ahead of the inlet while in supersonic flight. At low-speed and high angles of attack, these slots provided an escape for boundary-layer air which scrubbed across the fuselage ahead of the inlet. In 1968, the LERX were further enlarged, the forward portions continuing ahead as strakes almost to the nose.

The engines were fed by long ducts which admitted air from semi-circular inlets. These inlets originally were provided with a movable half-cone centerbody ahead of the wing. However, by 1971 it was concluded that Mach 2 performance was not all that important a design objective, and these conical centerbodies were eliminated. At about the same time, the inlets were made shorter and brought back under the LERX. That made the large LERX look a lot like the head of a cobra, so much so in fact that Cobra became the Northrop name for the P-530. The inlets were further refined throughout 1971-71, the final shape selected being a canted oval shape with a fixed, slightly-rounded edge, with the top located 4 inches below the underside of the LERX. The inlets were separated from the fuselage by a large rectangular splitter plate.

http://home.att.net/~jbaugher4/f17.html



No one calls them a "LERX." We call them a LEX: simply, "leading edge extension." LERX just sounds too much like that guy from the adams family.

They provide a lot of lift and significantly increase slow-speed, high AOA flying.
Matt



Yeah, LERX was new to me too. We always called them LEX.
Link Posted: 3/18/2006 5:08:53 AM EDT
[Last Edit: 3/18/2006 5:21:11 AM EDT by vito113]
Link Posted: 3/18/2006 5:29:09 AM EDT
[Last Edit: 3/18/2006 5:32:44 AM EDT by jimtash9]

Originally Posted By SkyCatII:

+1. Everything that I have heard about Russian quality control has been negative. One of the main problems is that pannels almost never seem to fit the way that they are supposed to, and I have never seen a Russian aircraft that looked like it was well maintained. That is not to say that they do not exist, just that I have yet to see any. The Russkies do have some pretty neat ideas, many of which the US should consider equiping our aircraft with (the helmet mounted IR missile sight comes to mind).



Soviet doctrine made the aircraft and pilots expendable because numerical superiority was to achieve the victory. Aircraft didn't need to be pretty or fit together well, they just needed the ability to be easily maintained and rugged enough to take-off from primitive airstrips. I'm sure that the Russians still practice that same strategy.
Link Posted: 3/18/2006 6:55:30 AM EDT

Originally Posted By Tomislav:
Give Russian designers access to Western manufacturing, and the results would be very interesting.



Clinton tried his hardest.....
Link Posted: 3/18/2006 10:07:59 AM EDT
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