REFLECTOR:Lower Winglets- Seaondary function.

[Tom Martino]

What is the latest thinking?  Again I must ask ... what would the guys
at the factory do on their "personal" V ... lower winglets?  Or not?
And can they be added to the regular tips?

 

-----Original Message-----
From: Chris Martin [mailto:christophercmartin@earthlink.net] 
Sent: Friday, January 30, 2004 4:28 PM
To: reflector@tvbf.org; reflector@tvbf.org
Subject: Re: REFLECTOR:Lower Winglets- Seaondary function.

Greg,

That is the very best explanation of the winglet I've ever heard. The
vectoring of total component lift replicates the vectoring of lift in a
dihedral wing. Brilliant, now I understand how it works and I've been
working on these planes since 1997 and flying them for over 400 hours.
It's
the occasional, inspiring, technical wisdom in the reflector that makes
the
entire reflector worth while reading. 

Great explanation!

Christopher Martin
christophercmartin@earthlink.net
Why Wait?  Move to EarthLink.


> [Original Message]
> From: Laurence Coen <lwcoen@hotmail.com>
> To: <reflector@tvbf.org>
> Date: 1/30/2004 10:30:52 AM
> Subject: Re: REFLECTOR:Lower Winglets- Seaondary function.
>
> Greg,
>
> The thingies on the ends of the main wing were not designed to be
winglets
> as a primary function. Their primary function is vertical
> stabilizer/rudders.  The fact that they are on the ends of the main
wing
> causes them to act as winglets, albeit poorly designed ones.  If you
> remember the Ercoupe, it had twin rudders on the end of it's elevator.
I
> can't remember anyone calling them "elevatorets".  The rudders always
wind
> up on the rear of the aircraft for the same reason the feathers are on
the
> back end of an arrow.  The Ercoupe had the big wing in front and the
little
> one in back.  Ours are built the other way around but the vertical
> stabilizer/rudder still has to go in the back.  Mounting it on the
> centerline isn't practical so they are out on the ends of the big wing
which
> is where you would mount winglets if you were going to have them.
Their
> primary functions are yaw stability, roll stability and yaw control.
The
> only one of these that isn't obvious is how they provide roll
stability.
> Assuming that you understand how dihedral on an aircraft provides roll
> stability by tilting the lift vectors in toward the center line of the
> aircraft, you should also understand how the "winglets" work.  The
winglets
> produces lift in the horizontal plane toward the centerline while the
main
> wing generates lift vertically.  If you sum these two vectors, the
result
> will be a lift vector tilted toward the centerline of the aircraft,
just
> like the wings with dihedral.
>
> Are we having fun yet?
>
> Larry Coen
> Std. RG-E
>
> ----- Original Message ----- 
> From: "Greg Poole" <gpoole@zeta.org.au>
> To: <reflector@tvbf.org>
> Sent: Thursday, January 29, 2004 3:41 PM
> Subject: Fw: REFLECTOR:Lower Winglets
>
>
> > From one of my aircraft designer mates.....
> >
> >
> > Subject: Re: REFLECTOR:Lower Winglets
> >
> >
> > > hi Greg,
> > > The lower winglet design on the Velocity is more a wingtip skid
than a
> > lower
> > > Whitcombe winglet. The upper winglet design is more somewhere to
put
the
> > > rudder than a Whitcombe winglet.
> > > An efficient design would have a winglet span of only 20% of the
main
> wing
> > > semi-span with the leading edge of the upper winglet starting at
the
> > thickest
> > > point of the main wing profile and ending behind the main wing
trailing
> > edge.
> > > The winglet is more tapered and sweptback than the original wing
and
the
> > > airfoil section changes the camber forward towards the tip(
geometric
> > > washout).
> > > The lower Whitcombe tip should be 5% of the wing semi-span (from
> > memory)and
> > > start before the leading edge of the wing, ending at the thickest
point
> of
> > > the main wing airfoil section. The upper winglet has the airfoil
as a
> bent
> > up
> > > version as the main wing whereas the lower winglet is opposite
with
the
> > main
> > > camber facing the fuselage.
> > > Modern design also cant the winglet out at 30 degrees to reduce
the
> > bending
> > > moment and pressure area at the winglet root.
> > > I hope this gives you a bit of an idea as to winglet designs,
> > > Ray
> > >
> > > On Wed, 28 Jan 2004 17:40:13 +1100, Greg Poole wrote
> > > > Al,
> > > >
> > > > Most of the designs of effective lower winglets as appear on
other
> > > > aircraft, kick the winglet out at a decent angle (rather than up
and
> > > > down) and have more of a tapered shape - I would love to know
the
> > > > reasons why the Velocity is different in this regard...can
anybody
> > > > shed any light? ....Could be better visual aesthetics I suppose.
> > > >
> > > > Forever curious!
> > > >
> > > > Greg in Sydney.
> > > >   ----- Original Message ----- 
> > > >   From: Al Gietzen
> > > >   To: reflector@tvbf.org
> > > >   Sent: Wednesday, January 28, 2004 4:59 PM
> > > >   Subject: RE: REFLECTOR:Lower Winglets
> > > >
> > > >   One notable result of not having the lower winglet is
increased
> > > > speed,
> > > >
> > > >   which doesn't quite jibe with the above discourse?
> > > >
> > > >   Scott
> > > >
> > > >   Oh, I think it could.  Airfoils producing a force cause drag.
The
> > > > winglets cause drag, but they produce a force we need for
handling
> > > > and stability.  I'd expect the Velocity lower winglets to cause
drag
> > > > at cruise without much in the way of offsetting benefit.
Apparently
> > > > there is some handling benefit at lower speeds.
> > > >
> > > >   Do you have any with/without data about the increased cruise
speed?
> > > >
> > > >   Al
> > >
> > >
> > > --
> > > ISPDr Internet WebMail (https://www.ispdr.net.au/mail)
> >
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