Vortilons

[4g_handicap]

Hi boffs,

The a/c I am flying now(ERJ135) had four vortilons located on each wing, just under the leading edge on the outboard portion of the wing.

Before I started flying ERJ, I had never heard of these things. On reading up, I could only find a vague reference to them that said they were like vortex generator's and can serve a similar aerodynamic function as the pylon that holds an underwing engine. <img src="confused.gif" border="0">

So, can anyone tell me more - I think that saying they are like vortex generators is oversimplified. Also they are located at the front of the wing, where I would have thought boundary layer energy is not a problem.

Thanks
4g
<img src="smile.gif" border="0">

[john_tullamarine]

I haven't seen the particular aircraft up close .. however, many of the LE flow control devices launch a vortex which then, itself, interacts with the flow pattern further back along the chord to provide the desired effect.

There was a thread some time back dealing with large nacelle VGs (eg 737, 767) which do just this to delay the stall a few knots ... some of the thread hyperlinks were to quite good photographs which showed the shed vortex curling over the leading edge of the the wing very clearly. Perhaps you might like to search for that one and take a look for interest.

My guess, at this stage, would be that the devices to which you refer do much the same or, perhaps, are intended to improve aileron behaviour at low speed.

[ 29 December 2001: Message edited by: john_tullamarine ]</p>

[Genghis the Engineer]

Like John, I've no knowledge of the type, but I know the Islander / Defender reasonably well which in the latter variant uses them to create a vortex back along the wing. This vortex creates an effective wall against crossflow. I wouldn't be surprised if that's the intent here. In the defender it's to keep the outboard section lifting at the stall and reduce wingdrop, but there may be other reasons.

G

[Sniff]

I think the thread that John talks about is here under <a href="http://www.pprune.org/ubb/NonCGI/ultimatebb.php?ubb=get_topic&f=3&t=002053" target="_blank">Nacelle Fins</a>

Hope it helps, Sniff

[Keith.Williams.]

In the spring of 2000 when I was preparing to teach the new JAR ATPL POF syllabus in PPSC I was comparing the learning objectives with my lesson plans to ensure all of the objectives would be satisfied.

One new objective included the purpose and operation of vortilons. I had never heard of them before so I consulted my colleagues and the various reference manuals held by the company, all to no avail. I then asked the CAA examiners and was told "Vortilons? Never heard of them". When I asked if this meant there were no questions on them in the new question bank, I was told "ERMMMM, Well no I suppose not".

I later found a reference in a copy of the Oxford manuals held by a student (Good old OATS)

It's funny how these JAA objectives and question banks got put together.

[ 30 December 2001: Message edited by: Keith Williams. ]</p>

[gas path]

Found this,if it's of any use!
<a href="http://www.alpa.org/internet/alp/feb01p22.htm" target="_blank">www.alpa.org/internet/alp/feb01p22.htm</a>

[ 30 December 2001: Message edited by: gas path ]
There's a reference to their use about a quarter way down

[ 30 December 2001: Message edited by: gas path ]</p>

[4g_handicap]

Thanks guys,

Sniff, I did find that thread - can't say it told me much, but it did contain a link to an interesting website full of other gen.

Gas path, thanks - I read the article but unfortunately it pretty much told me what I knew already.

I am still not sure how and why the vortilons are different to vortex generators. <img src="confused.gif" border="0">

[john_tullamarine]

I wouldn't worry too much about terminology here.

The generic term used (vortex generator, or VG) is quite descriptive. The shed vortex (very similar to a minature wingtip vortex) is used for a variety of purposes - to stir up the down chord boundary layer - especially to delay boundary flow reversal and main flow separation, restrict spanwise flow tendencies on swept wings, etc.

If you look at high performance fighters you see the use of vortex flow taken to extremes. The FA18, for instance, uses the wing leading edge extensions (the slender delta bits which run up either side of the fuselage) to shed vortices at high alpha which flow past the vertical fins to provide impressive high alpha manoeuvre capability. The aerodynamics are a bit different to those of a simple VG, but the end result (ie a shed vortex interaction with downstream flow) is much the same.

This industry loves jargon .. vortilon is just another term for a specific style of VG installation. Those of us with simple minds tend to call them all VGs.

[ 01 January 2002: Message edited by: john_tullamarine ]</p>

[Grendel]

Vortilons: In an old DC-9 new hire aerodynamics book from my present employer it is stated that vortilons were added to both lower wings inhibit spanwise flow on outboard wing sections at high angle of attack. This preserves lift on outboard wing sections and insures a positive nose-down pitching at higher angles attack.

It appears that vortilons have been used to avoid T-Tail deep stall. This was similar to what I was told by Flight Safety when I asked about them in Falcon-20 initial ground school.

Hope this helps.

[Killer Shark]

Yeah, that's about it. On the 125-1000 (Hawker 1000), vortilons are just more elegant wing fences. They replace sheet metal, replacing a pyhsical barrier to outboard flow with a strong vortex which goes over the upper surface, thus providing an impenetrable barrier of high energy air instead. The end result is the same, less outboard flow, desirable inboard flow separation first (less rolling moment), no unpleasant/uncertifiable wing drop, and the aircraft doesn't look as ugly to boot. Although, mind your heads - they're pointy (or knees on the -1000).

[hobie]

a simple description can be seen at ......

<a href="http://www.falconjet.com/pubs/falconer/frjun96/june-96-p2.html" target="_blank">http://www.falconjet.com/pubs/falconer/frjun96/june-96-p2.html</a>