Two questions!

On the Saab 340 the vortex generators were painted the same colour as the airframe, however the underside was painted yellow so that it would be obvious if any had fallen off. The only problem was that a large part of our colour scheme was yellow!!!

To compensate for the poor design of the ERJ Wing!

Oh behave.

WD has explained their function.

I’d say they are yellow so that they are highly visable. Would make quite a lot of damage if you walked into one! Yellow contrasts very nicely with the Grey/White colour of the wing.

If seen them in orange and red too.

WD why are those things in yellow so big on the ERJ wing?

Your confusing 2 different aerodynamic features. The fins long the top of the wing are vortex generators where as the “teeth” along the leading edge of the wing are Vortilons. Similar in theory but different (if that makes any sense).

I explained this in another thread but I’ll give another brief rundown again.

Swept wing jets are great at highspeed but have poor lift capabilities at low speed. As a result designers use leading edge devices (slats and slots) to help with lift at slow speeds as well as mid-wing or slow speed ailierons. The one byproduct of such features is weight due to the requried mechanics and additional parts. On a 150,000 pound aircraft such weight penalties are a small fraction of the overall aircraft but are rather unbearable for small jet design. So the Embraer engineers decided to use a rarely used aerodynamic feature, the vortilon. At cruise attitudes and speeds they create little if no drag. But as you near approach speeds with your higher angle of attacks the vortilons shed vortices to help with airflow specificly that affecting the ailerons.

They were originally designed for the DC-9 which have one rather large vortilon. They can now be found on more recent aircraft like the a few biz jets and even the 767 albeit much smaller.

The benefit is about a 10 knot reduction in approach speeds. The CRJ that has no leading edge devices averages or aerodynamic features approach speeds in the 140’s where we see approach speeds in the low 130’s. At lighter weights we can push about 120 knots which feels like you’re hanging out there.

To compensate for the poor design of the ERJ Wing!

You can’t be serious.

WD why are those things in yellow so big on the ERJ wing?

On a 4 engined jet it is preferable to do a rolling take off (particularly in a crosswind) as it reduces the chance of flow from the inboard engines affecting the intake for the outboards.

Yup, those are the vortex generators. The batch at the tip of the wing aides in aileron effectiveness and the other group helps with airflow over the flaps. Their placement either forward or aft along the wing chord gives the vortex generators effectiveness at different airspeeds. The more forward are usually associated with slow airspeed regimes due to higher angles of attack and the further aft they are installed gives them a better effectiveness at higher speeds.

If someone else has a better (or correct 😉 ) explaination please chime in.

my mistake

Here is the image Oops.

However I know well what winglets are but I don’t how these wing thingies are called.

Thanks for the info and let’s see if you were discussing the same thing 🙂

cheers,

[Wing… thingies]
In an airliner nothing left unneeded so of course everything has got a reason to exist and a use. Now could anyone tell me what the “tips” circled in my attachement are for (photo: courtesy of Wannabe Pilot)?

On a recent 737 trip I noticed these and they didn’t seem to be aligned like in the pic but rather forming a bizarre curve. I guess it’s something to do with guiding the airflow… :confused:

Without seeing the pictures I would guess that you are referring to the vortex generators on the top of the wing long the outer portion. You would be correct to think they are used for airflow. They are used to create vortices at higher speeds to prevent airflow seperation from the surface of the wing, specifically across the aileron flight control surfaces.

There’s my answer without the picture, how did I do? 😀

But if she is referring to her recent EasyJet trip, it cant be winglets because no Easyjet 737s have winglets ?

I guess the position and hold is more used at busy airports to ensure good traffic flow?
About your Wing thingies, who are called WINGLETS (on A320’s wingflags), go here: http://www.boeing.com/commercial/737family/winglets/index.html

Or if they take off with no stop it might be an ‘immediate take off’, usually when another aircraft is coming in

[Wing… thingies]
In an airliner nothing left unneeded so of course everything has got a reason to exist and a use. Now could anyone tell me what the “tips” circled in my attachement are for (photo: courtesy of Wannabe Pilot)?

On a recent 737 trip I noticed these and they didn’t seem to be aligned like in the pic but rather forming a bizarre curve. I guess it’s something to do with guiding the airflow… :confused:

[Take off]
I was wondering if there was any policy or best practice when an airliner lines up on the runway: is it up to the pilot to choose between a rolling start and a static start or are there any rules?

Some seem to clearly mark a halt before applying full power and some others just don’t stop and accelerate straightaway.

Thanks guys

I do not see any pic.

But to answer your question on the take off.

Sometimes Pilots are instructed to “Position and Hold” This means to line up on the runway and await clearance to take off. Thats when you notice a wait.

Other times and more often, Pilots are simply given clearance to take off. This is generally when a the Pilots roll their aircraft onto the runway, line up and begin take off with no stop.
Sometimes they will stop for a moment to complete any procedures left to do in the cockpit before begining the take off roll.