I think Taylorcrafts use an incidence angle of 2-1/2 degrees with the a/c level based on the rigging infofmation I found in a T'craft service manual and a plot of a NACA 23012 airfoil, but I'm not yet 100% certain of this. This does make sense, however, since this would provide a lift coefficient of 0.40. As the AOI (or AOA) increases the lift coefficient also increases. for example, an AOA of 3 degrees gives a lift coefficient of 0.45, AOA of 4 deg. gives a lift coeff. of .55. This continues almost linear until the max lift coefficient is exceeded and the wing stalls. If the wing AOI is 2-1/2 degrees with the a/c in level flight at 4,000' msl at 100 mph (147 ft./sec.) with 180 sq. ft. of wing area the wing would produce about 1,643 pounds of lift. This amount of lift for a typ. T'craft cruise speed might be a little high, so the AOI might be a little lower - I don't know - yet.
The interesting thing is that I have compared the T'craft 23012 airfoil to the NACA 4412 airfoil used on Champs (gotta be simmilar to the Cubs airfoil) and did not see any lift or drag benefits going to the 23012 airfoil. Another interesting thing is that clipping the wings does not decrease the the amout of wing drag much at all. What you loose in parasite drag you gain in increased induced drag since the wing loading increases.
The 23012 airfoil does have two benifits over the 4412 as I see it. First, the almost symetrical airfoil of the 23012 would perform much better in sustained inverted flight - not something I'm looking for, but it would be a benefit. I think the real benefit of the 23012 is in it's reduced nose down pitching moment. The less of a pitching moment the the wing generates the less of a down force the tail must make (which the wings see as add'l weight and increased wing loading = yet more induced drag). Also, the more the tail must push down the more trim drag produced by the horizontal stab - more drag again. I think this is why the T'craft is faster than the Champs and Cus on the same HP.
The thing that has got me thinking now is the fact that a T'craft is a side by side seat aircraft which allows a designer to specify a narrower C.G. range and still have a practical flying airplane. With a tandem arrangment it is much easier to get into an aft. C.G. loading. I gotta be careful with this one. This in its self may help an airframe fly faster on an equivlent HP - food for yet more thought.
I'm not an Aeronautical Engineer. I'm just trying to justify the use of the 23012 airfoil and short wing on an experimental and want to know why it seems to work so well on the T'craft and other airframes. I appreciate all the responses to my post. Just when I'm about to give up on the T'craft airfoil, I see the stuff you guys posted and it seems worth looking into further.
Thanks Again, Derek
