What is that part of the wing doing?

[Megagoth1702]

Sorry for the really stupid thread title, but I don't know how else to call it.

 

 

Question - there is a part of the wing, very close to the plane itself, that has a "no step" mark on it. It goes up and down, kinda lifts itself when the angle of attack is high. What is the purpose of this part of the wing?

 

Thanks in advance.

[sobek]

Question - there is a part of the wing, very close to the plane itself, that has a "no step" mark on it. It goes up and down, kinda lifts itself when the angle of attack is high. What is the purpose of this part of the wing?

 

Usually those are called leading edge flaps or slats and serve to let the wing generate more lift in slow flight. In the A-10, they are there so the flow does not separate from the wing too early, because it would disturb the engine inlets in high AoA situations, possibly leading to compressor stall related flameouts.

[Megagoth1702]

Thanks.

 

Wow, it is so sick what you have to think of as an aircraft engeneer...

[sobek]

Wow, it is so sick what you have to think of as an aircraft engeneer...

 

That's what prototyping is for. ;)

[159th_Falcon]

Not sure but i guess your referring to a part of the wing called a Slat.

 

A normal wing whit a certain profile will stall (lose lift) at a certain angle relative to the flow of air that goes over it.

Whit a Slat above a certain angle that Slat extends changing the profile of the wing whit the purpose of retaining lift were the wing normally would stall.

 

workings are a bit more complicated and require knowledge of aerodynamics to understand. But in basics that's what its for. To be able to fly at higher angle's of attack.

 

Also kinda fun to know is the fact that you don't need any form of power to extend it. It happens by itself due to the aerodynamic forces acting upon it.

So you won't find any controls in the cockpit for it.

 

~S~

 

Sniped............

 

@ Sobek, i'd go for Good and Fast :joystick:

Edited November 24, 2011 by 159th_Falcon

[Eddie]

Also kinda fun to know is the fact that you don't need any form of power to extend it. It happens by itself due to the aerodynamic forces acting upon it.

 

Not on any aircraft I've ever worked with. Most use electrical or hydraulic acuators or screwjacks.

 

In the case of the A-10 there are 2 hydraulic actuators for each slat running off the right hydraulic system.

[Yo-Yo]

Not sure but i guess your referring to a part of the wing called a Slat.

 

A normal wing whit a certain profile will stall (lose lift) at a certain angle relative to the flow of air that goes over it.

Whit a Slat above a certain angle that Slat extends changing the profile of the wing whit the purpose of retaining lift were the wing normally would stall.

 

workings are a bit more complicated and require knowledge of aerodynamics to understand. But in basics that's what its for. To be able to fly at higher angle's of attack.

 

Also kinda fun to know is the fact that you don't need any form of power to extend it. It happens by itself due to the aerodynamic forces acting upon it.

So you won't find any controls in the cockpit for it.

 

 

... because there is an automatic system controlling slats hydraulic actuators. But generally you are right - WWII era planes have slats that can extend and retract itself due to the air pressure distribution at low and high AoA. If they extend not simultaneously it leads to departure.

Modern planes generally extend slats using hydrolic actuators in the same time they extend flaps.

(Su-25, Su-27, etc)

[Snoopy]

The slats are controlled by the right system (like stated above). The slat transducer is located on the right leading edge of the wing next to W79 (SPR door). The transducer is not actually terr in the sim. The original A-10s did not have any slats. They were added early in tearing because how easily the engines were stalled during maneuvers. The only reason the slats were added was to direct airflow into the engines during high AOA maneuvers.

 

If you have no hydraulic pressure (right system) airflow will cause the slats to extend/retract.

[sobek]

@ Sobek, i'd go for Good and Fast :joystick:

 

Sorry, i ran out, will fast and cheap do the job? ;)

[Avilator]

Okay, I'll try my hand at a visual explanation. The first image is at a low angle of attack. The flow around the wing is nice and smooth, and thus stays "attached" to the wing over the vast majority of its travel distance.

In the second line, the wing is at a high angle of attack, but without slats. The air by itself doesn't have enough energy to "make the turn" around the leading edge of the wing. The flow separates and becomes turbulent. This turbulence propagates towards the engines, and they throw a fit.

In the last line, slats are added, which help turn the flow onto the upper surface of the wing. The flow stays attached for longer, and the engine is happy.

 

 

 

So, in a word, slats allow a given wing to fly at a higher angle of attack without flow separation, which is what constitutes a stall.

[Megagoth1702]

Hah, thank you! :) I get it now.

[Juuba]

Well, the engines being fed dirty air is only one part of the equation.

E.g For WW2-era (like the Bf-109 for example) the engine &propeller was in front. Or the engines can be in or below the wings.

 

Still they (the wings) take advantage of the slats and their effect on the air flow.

 

It just makes the wing "take hold" of the air better, slows the stall speed down.

[sobek]

Well, the engines being fed dirty air is only one part of the equation.

E.g For WW2-era (like the Bf-109 for example) the engine &propeller was in front. Or the engines can be in or below the wings.

 

As was said, in general they are used so the wing can perform under higher AoA situations. In case of the A-10, they are there to protect the engines, else they would extend over a much larger area of the leading edge.

[TigersharkBAS]

Also kinda fun to know is the fact that you don't need any form of power to extend it. It happens by itself due to the aerodynamic forces acting upon it.

 

 

I didn't know that. Learn something every day. Thanks for that fun fact!

[Eddie]

I didn't know that. Learn something every day. Thanks for that fun fact!

 

It's a fun fact that is only applicable to light aircraft and pre jet military aircraft. Certainly not the A-10.

[elchacal]

Very clear explanation..!

[WildFire]

Legendary picture.

[Avilator]

***snipped*** It just makes the wing "take hold" of the air better, slows the stall speed down.

 

The stall speed only goes down in 1G flight. Remember that a stall has nothing to do with speed and everything to do with AoA. In that regard, slats allow flight at a higher AoA.

 

 

It's a fun fact that is only applicable to light aircraft and pre jet military aircraft. Certainly not the A-10.

That fun fact also applies to the A-4 Skyhawk. From wikipedia: "The leading edge slats were designed to drop automatically at the appropriate speed by gravity and air pressure, saving weight and space by omitting actuation motors and switches."

 

Also, according to the A-10 manual, if hydraulic pressure is lost, the slats will extend and stay there.

 

Legendary picture.

Why thank you.:)

[159th_Falcon]

It's a fun fact that is only applicable to light aircraft and pre jet military aircraft. Certainly not the A-10.

Except for when HYD SYS #2 is lost, then its the air flow, as said by paulrkiii:)

 

Anyway, good information everyone guess we all learned here.

And if its true that only light planes use aerodynamic forces for the slats then my teacher lied to me. (wouldn't be the first time though:huh:)

 

@ Sobek, no, cheap and fast wil NOT do. Ill go spend my money somewhere else.:D

 

~S~ and nice drawing ya made Avilator, especially those smiley's