Hi Ren.
I cannot answer your question directly. However...
XFLR5 is much easier to use than xfoil - it can be thought of as a better front end to xfoil as it uses it for its calculations. But you can zoom in on the graph.
A LPP should fly at around Re9000 to 10000 based on measurements of LeRoy's Cesar Banks LPP I made earlier this year. So that should help.
Regards.
Mike Kirda
--- In Indoor_Construction_at_yahoogroups.com, Nick Ray <lasray@...> wrote:
>
> Hi Ren,
>
> Since your daughter is working on this for her science fair project it may
> be worth looking at happens as you vary camber in xfoil.
>
> http://web.mit.edu/drela/Public/web/xfoil/
>
> Pay careful attention to what happens to lift and drag as the camber
> percentage changes.
>
> If you have an iPad handy Wind Tunnel Pro will do similar calculations in a
> an easier to use manner.
>
> Regards,
>
> Nick
>
>
> On Wed, Oct 30, 2013 at 9:19 AM, <nmonllor_at_...> wrote:
>
> > **
> >
> >
> > Hello everyone,
> >
> >
> >
> > I've come across many plans where two differnt percentages of arc have
> > been presented for different cieling heights. An example of this would be
> > in Ron Williams' book Dennis Jaeck's Pennyplane #2 on page 91. There have
> > been others too.
> >
> >
> >
> > On this particular model plan it states:
> >
> > high cieling: 4% arc
> >
> > low cieling: 6% arc
> >
> >
> >
> > The first time I saw this, I figured it had to do something with lift,
> > Bernoulli's law and so on. At the time, I didn't give it much thought as I
> > just wanted to build a plane that flew. Since then though, I've come across
> > it again and again on other plans and thought I'd take a look at why this
> > was so.
> >
> >
> >
> > Well, my daughter Gabby is doing her science fair project on how differnt
> > arc radius airfoils affect the flight of her Pennyplane. BAM, right between
> > my eyes!!! The question arises again, but this time with a purpose.
> >
> >
> >
> > I thought it had to do with lift but, does it?
> >
> >
> >
> > A smaller percentage would create a higher hump in the air foil increasing
> > lift according to Bernulli, but yet it is suggested for a lower cieling.
> > Whyis this?
> >
> > What am I not seeing?
> >
> >
> >
> > Please help me understand.
> >
> >
> >
> > Thank you,
> >
> >
> >
> > Ren
> >
> >
> >
>
Received on Wed Oct 30 2013 - 06:50:51 CET