possibly the most important is the laminar flow wing. The wing is not dissimilar to some other more modern planes.
Don't get caught up in the marketing hype for the "laminar flow" wing in light single-engine airplanes.
Despite claimed advantages in high-power, high-speed aircraft, with perfectly-conforming construction and uncontaminated surfaces (think North American P-51), it also has some disadvantages. Its primary benefit in 150-knot spam-can bugsmashers is not in aerodynamics, but in
packaging.
The NACA 6-series (so-called "laminar flow" wing) has its maximum thickness -- and therefore its main spar -- further aft than conventional airfoils. That allows the designer of a low-wing airplane to stow the main spar carry-through out of the way under the second-row seat, as in the Mooney M20, Beech 23/24, Rockwell Commanders and Piper PA-24, PA-28 and PA-32 lines. By contrast, a Beech Bonanza has a NACA 23012 wing, and its spar carry-through goes under the front seats, where it interferes somewhat with forward-facing second-row passengers' legroom.
The only high-wing Cessnas that have NACA 6-series airfoils are the 1968-69 C-177 Cardinal and 1967-86 C-210 Centurion. Why? They are also the only strutless high-wing Cessnas. A spar carry-through must pass through the cabin ceiling, and the designers wanted the carry-through to go behind the heads of the front-seat occupants. Had they just used the original NACA 2412 wing in a strutless configuration, the spar would be right at the pilot's head.
One characteristic of NACA 6-series airfoils is that drag increases rapidly at higher angles of attack. This is noticeable if the pilot attempts to rotate too early on takeoff; drag rises sharply and, if the airplane is at all underpowered, the takeoff becomes sluggish, or in extreme cases, impossible. It's not so much a problem if there is a surplus of power (e.g., P-51; to a lesser extent C-210) where the airplane can just power through the high-drag regime to a lower AOA, but in a lower-powered airplane (
e.g., the original American AA-1 Yankee and 150 hp Cardinal) it's a problem. The sharp leading edge can also lead to more abrupt stalls.
As a result, the airfoils of several "laminar-flow" light airplanes were modified with more rounded leading edges, resulting in less drag at higher angles of attack, gentler stall characteristics, and little, if any, loss of cruising speed. Examples include the Cessna 177B Cardinal and 177RG Cardinal RG; Grumman-American AA-1A (and all Grumman-American two- and four-seaters thereafter); and the outer panels of the taper-winged Piper PA-28 and PA-32 series. Even Mooney fussed with the outboard leading edges in the "twisted-wing" M20F and M20G from 1966 to mid-1968.
Beech tried and rejected the "laminar" wing for the Bonanza -- twice. The first Bonanza prototype (1945) had a "laminar" wing, but after testing they went with the NACA 23 series for production. They tried again in 1961 with the experimental "Model O35", with a "laminar" wing and trailing-beam main gear. Cessna flew an experimental strutless 182 with "laminar" wing, as well as a proposed Cardinal-like 182 replacement, the Model 187. All of these were abandoned because they did not offer significant advantage over the originals.
At the end of WW2 North American Aviation built a four-seat lightplane (Navion) with obvious P-51-inspired styling cues ... but instead of a "laminar" wing it had a high-lift wing with concave lower camber. There is even some debate about how much the "laminar" airfoil contributed to the P-51's performance, or whether credit should go to "the very good manufacturing standards at NAA" (
http://www.wp1113056.server-he.de/ABL/20-forschung/laminarfluegel/laminarfluegel_en.htm).
Is the so-called "laminar flow" wing common on "modern" lightplanes? Cirrus uses the new, non-symmetrical Roncz airfoil, as does the RV-9. All other two-seat RVs use the NACA 23012. Neither Cessna nor Beech currently builds anything propeller-driven with a NACA 6-series airfoil. Piper PA-46 has the NACA 23015.
Modern high-performance sailplanes do have laminar flow wings. Their smooth, precise composite wing construction allows them to actually maintain maximum laminar flow and reduced drag. In typical metal airplanes, on the other hand, slight surface imperfections, skin seams, oilcanning (from wide rib spacing and thin skins), rivets, bugs, fuel caps, hinges, landing lights, misrigging, etc., all tend to negate any aerodynamic advantage.
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