WIG Airfoil

durabol wrote:
I am planning on building a plane that is towed behind a boat. Because
of the low speed (25mph stall) I am planning on using a high lift
airfoil. Some airfoils with high coefficients of lift a FX72150B
(2.0), FX73CL3(2.25), GOE225(1.9), GOE226(1.9), GOE234(2.0), GOE243
(2.0), GOE244(2.0), S1210(2.25), S1221(2.2), S1223(2.3), S1223RTL
(2.5). This is a link to the airfoils and polars: http://www.kaiyipboxing.com/WIG/INDEX.HTM
I know some of these airfoils are for model airplanes and might not be
suitable. Some also have very thin trailing edges which may be hard to
build. I don't know very much about aerodynamics so I was wondering if
anyone has any opinions.

Brock

Before I'd consider any particular airfoil, what's your Reynolds Number
range?

Before I'd consider any particular airfoil, what's your Reynolds Number
range?
--------------------------------------------------------------------------------------------

"Towed by a boat" and "..stall speed of 25mph" pretty well defines
the lower end of the envelop.

Since the thing is a water craft, apparently meant for recreational
purposes we can assume two-place, side-by-side for the load and a
stepped hull, probably with a T-tail. As with most water craft it
probably needs to be designed to allow it to be taken to where the
water is. The need for portability tends to suggest a wide-chord, low-
aspect wing, probably strut-braced to improve it's portability and
ease of set-up, which points us toward one of the low-speed airfoils
developed at Gottingen University during the 1920's... or an RAF-
series airfoil from the same era... or something from the fat end of
the 23000 series...23021 or whatever... but that would probably want a
full-span, all-flying Junkers 'aileron' for control, as mentioned by
Oliver. Brian's mention of biplane wings is a hands-down winner for
strength but becomes a mare's nest when it comes to portability and
ease of erection.

As for getting off of the water and into the air I think the real
problem is getting free of the water without the characteristic 'pop-
up.' In any case, the fact you want it to take-off and land on
water,, plus the fact it is a flying boat rather than an airplane on
floats, means it's going to have to be hell for stout if you want it
to last more than one season.

----------------------------------------------------------------------------------

As always, this Group can over-engineer the thing for you :-) Or you
could just jump right in, whip something out and play with it until it
breaks.

-R.S.Hoover

Bob wrote:
As always, this Group can over-engineer the thing for you :-) Or you
could just jump right in, whip something out and play with it until it
breaks.

An old contrarian saying comes to mind: "A month in the lab can save you an
hour in the library."

In this case I say it never hurts to try to sit down and try to make some
estimates, however rough. Otherwise yes, one can always start building
something and after enough trial and error construction and testing
eventually come up with something.

Jim Logajan wrote:

An old contrarian saying comes to mind: "A month in the lab can save you an
hour in the library."


Every time!

On Jun 22, 5:32*pm, cavelamb wrote:

An old contrarian saying comes to mind: "A month in the lab can save you an
hour in the library."

Every time!

Not every time! You never did the book research and then tried to
apply it ............... only to find out the author didn't have any
real world experience?

Bought an EconoTIG years ago. Wasted money on published (not direct
advertising) "expert" advice.
=================
Leon McAtee
Always on the look out for contrary points of view.

wrote in message
...
On Jun 22, 5:32 pm, cavelamb wrote:

An old contrarian saying comes to mind: "A month in the lab can save
you an
hour in the library."

Every time!

Not every time! You never did the book research and then tried to
apply it ............... only to find out the author didn't have any
real world experience?

Bought an EconoTIG years ago. Wasted money on published (not direct
advertising) "expert" advice.
=================
Leon McAtee Always on the look out for contrary points of view.


However, he did say an hour in the library, not an hour with a random book.

I have been tricked as well, although in my case, it was a class in
mechanical drafting--in which the Prof prattled on, asserting that he
understood common processes, but clearly had no clue at all how a sheet
metal brake actually stretches metal.

Peter