Erik Johansson

I have done some searches and think I have found some pretty decent explaination of why an airfoiled horisontal stab is beneficial, but I would like to know more about the vertical tail and how much, if anything, would be lost by making it flat (with the usual sanded LE and thinned out TE).

/Erik

bla bla

It looks a s#it load better!

50%plane

My Feedback: (5)

better knife edge

ofremmi

Hi
The smoothness of rudder input is much better.
Ola

Erik Johansson

What kind of magnitudes are we talking about here? The particular plane I have in mind has a vertical stab built like the one on the Curare with a thick LE that is sanded to form the frontal part of the "airfoil and then it´s a constant taper from the high point to the TE.

I also edited my first post as I found a quite serious typo (it said "vertical" instead of "airfoiled" ).

/Erik

tommy s

My Feedback: (55)

I know a flat stab and elevator has a slight dead spot around neutral so I would
assume the same is true for the rudder.

tommy s

wladkummer

My Feedback: (7)

At such small Reynolds number I think even diamon shaped airfoil would suffice...would be an interesting testing, huh?

tommy s

My Feedback: (55)

Already been tested. In the "old" pattern days Jim Kirkland did extensive testing
when designing his Intruder pattern ship and found a diamond shape stab is just
as effective as an airfoil shape.

tommy s

Erik Johansson

Maybe a stupid question but what does diamond shape mean in this particular case? I´ve just never seen it before to describe an airfoil shape (but it´s obviously common as a google search generated lots of results). I think I can guess what it means, but it´s always nice to be certain.

/Erik

stek79

Hi Erik,
what good reasons did you find that will make an airfoiled solution better than a flat one (horizontal stab I mean)?

Thank you!

OhD

Erik,
The early diamond airfoil stabs were made by outlining the stab with a quarter to three eigths inch square balsa and then installing square stock to make a truss instead of parallel ribs. Then a strip of one eigth by one half was layed along the desired high point from root to tip, top and bottom. The leading edge and tips were rounded and finally the assembly was covered with silk and dope so the cross section would look like a diamond, being flat from high point to leading edge and also flat back to the trailing edge (hinge line). Notice I said silk and dope so you know how long ago that was. No such thing as Monocote.

Regards, Jim

OhD

Make that eighths and one eighth.

Rhilluk

I draw a fuselage and stick it in our CFX computer wind tunnel, see what that will chuck back at me