EMB 145 wing ?

[Bearcat]

Guys I travelled on a EMB the other day and noticed the vortex generators on the top of the wing. Please tell an old man what benefit are the strakes that look like missile holders that protrude from under the wing?

Rgds The Bear

[flite idol]

I think they are called vortillons (sp?). Allegedly they help prevent spanwise airflow at high AOA`s by energising the airflow over the airfoil surface.?

[nitefiter]

4 vortilons are installed on each wing to increase airflow over the ailerons at low speeds, they are also supposed to help lower the stall speed.

[Bearcat]

I have never seen this before on a public transport aircraft.....is it to say that the wing is inefficent in the low speed regime that these devices need to be fitted?

Thanks for all your previous answers

[Siddique]

Try the VC10? Had a kin great fence on the leading edge. In fact 2 I think? The HS125 I think as well? Also the 'slot' on the Leading edge of the lightning performed a similar function I believe?

[flite idol]

The falcon 20 also has midspan fences that apparently in latter years were proven to provide no aerodynamic benefit. As the aircraft was type certificated with them it was too expensive to subsequently remove them. Could be an urban myth, anyone know.? Ever been at the hold line behind a Beech 1900.? That thing is bristling with stickeyout aerodynamic gizmo compensators.

[Flying Clog]

flite idol,

You've got it in one! That's exactly why the ERJ series carries the yellow 'bomb pylons'.

[john_tullamarine]

The majority of these flow control devices are either wind tunnel or flight test fixes (and the 1900 is a good example) for inadequacies (unfortunate or intended) in the original design.

They all do much the same sort of thing in that they provide a local and comparatively high energy airflow stream which interacts with the existing wing flow to improve deficiencies which are found to exist during the certification program.

Examples are to delay separation (shed vortex from a nacelle strake or LE VGs) to improve stall speeds or aileron control through to fences/notches/VGs to restrict spanwise flow.

[xdc9er]

DC -9's had them too!, some thing about spanwise energizing the airflow, or was that what happens at altitude after the bean burritto.

[FE Hoppy]

The l1011 -500 wing was different on the UK reg jets compared to the rest. To meet uk g loading requirements 20 vortex generators were added to the upper surface of each wing. I've flown both types and the only difference noticable is a very very small increase in fuel burn. . .Other devices include "t" shape trailing edges and chouchelmin (sp) carrots. They are all used to fix flow seperation problems at various flight configs. You cannot build a wing that does everything perfectly there is always a compromise.. .Flaps and slats are the most obvious examples of this.

[The Nr Fairy]

If I'm following this correctly, then I remember seeing a piccie of a MIG-17 or -21 with wing fences.

The text accompanying the piccie had a quote to the effect that someone suggested the only reason they were there was to prevent the airflow from defecting !

[Stagnation Point]

Didn't the F4 have a Dog Tooth on the leading edge and the Bucaneer had a blown wing. Tiny holes on the up surface of the wing expelling bleed air from one of the engines. Which meant if one of the engines failed you not only lost thrust but a portion of lift as well. From what I was told though it made it a very nice acft to fly.. .. .The Metro three has a fence just inboard from the landing light nothing aerodynamic just prevented the pilots from looking directly at the landing light.

[nitefiter]

Stag. .The Phantom F4 series did have a "saw tooth" leading edge.

[Zeke]

The ERJs don't have leading edge slats so they installed vortilons helping out the ailerons at high angles of attack. The upper surface of the wing also has vortex generators on the surface as an added help. They work in a similar aerodynamic fashon as a stall fence. Hawker replaced the stall fence on the 800A with vortilons on the 800XP.. .. .Apparently vortilons originally were used by Douglas while developing the DC-9, they have found their way onto other bizjets like the Hawker 800XP and GIV. The 800XP uses one large one, GIV uses 4 on each wing.. .. .JT,. .. .Dont think the 1900 is a good example, the stabilons are there to improve the cg range from 4% to 40% mac, improved pitch stability, and positive recovery from deep stall.. .. .The tailets and the vortex generators near the wing fuse interface improved the directional stability and reduced stall speeds.. .. .Z

[BLACK RAT]

And they are painted yellow to try and prevent you from walking into them and ripping your head open.It doesnt always work,believe me oowch.

[john_tullamarine]

Zeke,. .. .Re-reading my post it is clear that I was a bit careless with my words. . .. .What I had intended to suggest was that the 1900 was a good example of an aircraft which ended up with lots of fixes. I hadn't intended to suggest that it was a prime example for wing fixes, however. . .. .I really must be more rigorous and attentive to semantics, mustn't I ?