REFLECTOR: Vortex Generators

[Lawrence Epstein]

John-

Just to be clear, are you agreeing or disagreeing with me? ;-)


On Mon, May 19, 2014 at 10:08 AM, <john at velocityaircraft.com> wrote:

> VG's can go on the main wing only, canard and main wing but not the canard
> only unless specified by the factory.  You dont want do as Larry said an
> stall the main wing first.  If you are landing at 97kts then you have
> something else wrong with the plane though.  First check pitot static and
> make sure they are correct.  After that, make sure you have correct throws
> for the controls.  26-28 degrees trailing edge of elevator down and 22 up.
> If you are getting over 28 degrees down you are stalling the canard.  If
> you are only getting 15 degrees trailing edge down then you aren't getting
> the full effect of the elevator.
>
> Unless your plane is very nose heavy empty (100 plus pounds) then you
> should be seeing between 80-85kts down final.  At 97 your float and landing
> roll must be fairly long not to mention brake fade and tire wear.  If you
> are getting the correct throws then check incidences on the wings and
> canard.
>
> As for the vortilons.  The plane is NOT unsafe without them as testament
> to hundreds flying without them.  You will notice the plane handling to
> increase a little at slow speeds due to them reducing span wise flow under
> the wings.  We don't put them on ours so I don't have to clean around them
> and people hit them at shows (same as the VG's).  If you feel like the
> plane is squirrely then you can try putting them on and seeing if that
> helps a bit.  The same is with the winglet bottoms, they do a similar thing
> to help prevent the air from dumping over the tip which also helps the
> plane fly straighter when slow.
>
> John
>
> ------------------------------
> -----Original Message-----
> From: "Lawrence Epstein" <ljepstein at hotmail.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Date: 05/19/14 07:01
> Subject: Re: REFLECTOR: Vortex Generators
>
> I would not put VG's on the Canard without also putting them on the main
> wing. (without some real engineering input).
> If you do put them on the canard, be very careful about your flight
> testing.
>
> A main feature/requirement of a canard aircraft is that the canard
> *ALWAYS* stalls before the main wing. If you enhance the lift of the
> canard, the main wing might stall first, leaving you in a deep
> (unrecoverable) stall.
>
> Larry Epstein
> 173 FGE
> N58LV
>
>
>
> On Sun, May 18, 2014 at 11:42 PM, Brian Michalk <michalk at awpi.com> wrote:
>
>> After doing my foreward CG tests, I find that my biggest concern is
>> running out of elevator authority when flaring to land. Flying in my
>> buddies V, and also the trainer, I don't recall speeds as high as I am
>> maintaining on final. At 110mph (96 kts) final, by the time I land, I
>> suppose I'm down to 100mph, and at forward CG of ... well, I can't find my
>> spreadsheet at the moment, but it's probably close to 115 inches.
>>
>> My question is I am wondering if VG's on the canard will give me some
>> better elevator authority. I like not having to worry about breaking them
>> off now, so if the bother is worth it, I'll try them.
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>
>
>
> ------------------------------
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