Not to butt in=2C but as you all know=2C I have flaws...
Wing tip design is to control vortices as we all know. Mr. Dykins did a gr
eat job of designing the wing with the tip creating virtually no lift at cr
uise speeds of 130 KTS and up to 10=2C000 MSL. Therefore=2C in my opinion
=2C an aerodynamic gimmick to reduce tip drag is not necessary=2C unless fo
r cosmetics or utilty.
For those of you unfamiliar=2C the Europa wing lift distribution is very ne
arly elliptic (optimum)=2C giving the least induced drag at low altitude cr
uise. Wing tip redesign is only necessary if the wing loading or wing lift
distribution is not elliptic and a large vortex is generated by the wing t
ip=2C adding drag. Horner tips or winglets work when the big square wing h
as a large vortex created at the tip due to lack of twist=2C so the added f
rontal area drag is compensated for by the reduced vortex drag. And frankl
y=2C the increase in wing area at the tip reduces the stall speed=2C not th
e shape in GA aircraft. On large aircraft with swept wings=2C winglets hel
p break down tip drag and tip losses due to the wide flight envelope of the
aircraft.
Should we ask our Europa wing design to lift another 500 pounds of airplane
=2C or cruise above 20=2C000 MSL=2C wing tip design may be relevant. I lik
e what Claude Tugwell did on his classic. He made the tip to include a sli
ght Horner dip adding about 6 inches from aileron end to the tip. It makes
grasping the tip for carrying=2C rigging and de-rigging easier=2C but does
n't do a thing for speed.
A Plane Jane wing tip isn't sexy=2C but it works if the wing design is righ
t. As one of my aerodynamics instructors (Mr. Bonde=2C who worked on the o
riginal 727 wing) said in college=2C "Tip design can be a flat plate if yo
u got the lift distribution right".
We'll talk more at Sun n Fun over a bit of libation.
Now I have to get the displays ready for Sun 'n Fun.
Bud Yerly
Custom Flight Creations (813) 653-4989
> Date: Fri=2C 17 Apr 2009 19:35:19 +0200
> From: frans@paardnatuurlijk.nl
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Re: Jabiru Cowls
>
l>
>
> Graham Singleton wrote:
> > I used to try and get Don (and Ivan) to explore wing tip design but he
> > never would=2C he felt that in the cruise the induced drag was so low
> > (because of the wing area) that it wasn't worth the troublel=3B probabl
y
> > true for the cruise but not true for climb.
>
> I recall having read somewhere that for the speeds reached by
> GA-aircraft=2C any improvements by winglets etc. is countered by the
> additional drag (frontal area=2C friction drag). If you see winglets=2C i
t
> is usually the result of fashion=2C not science.
>
> --
> Frans Veldman
>
>
===========
===========
===========
===========
>
>
>
|