Continuing Ed

Look across almost any airport ramp and you see a lot of sameness. Sure, there are high wings and low wings, and aluminum, fiberglass, and tube-and-fabric airframes. But other than that, the airplanes look pretty much the same: piston engine on the nose, conventional empennage at the rear, and a wing with ailerons and flaps. Not a lot of diversity there. Look closer, however, and you begin to see small differences between the various makes and models. Different wing planforms, different sizes of ailerons and flaps, different approaches to pitch control, different ways of steering an airplane on the ground. It’s these seemingly minor differences that matter—and that add challenge to transitioning from one make and model to another.

Every airplane design is a product of many factors and considerations, ranging from mission objectives to manufacturing ease and cost. Some exhibit a design approach that can best be described as corporate-committee bland, while others bear the personal beliefs of an individual designer. The fun part for pilots is identifying the unique features of a particular design—the little things—and evaluating how those features influence handling and performance.

It’s hard to identify a current-production airplane that reflects the personality of an individual designer. The reality of contemporary aircraft manufacturing economics, regulatory requirements, and the marketplace combine to encourage an engineered sameness. You have to look back in the past—when it was possible for one person with an idea and the passion to pursue it—to find airplanes with unique features.

One such airplane that stands out as a signature design is the Ercoupe. Designer Fred Weick was passionate about building safety into aircraft. The Ercoupe embodies many of his safety concepts, with the result being a distinctly different-looking and -flying airplane.

Perhaps the most unusual feature of the Ercoupe is the lack of pedals to control the small rudders on the dual vertical fins. Instead of employing rudder pedals, the Ercoupe’s unusual steering wheel controls the rudders along with ailerons and elevator. Interconnecting the ailerons with rudders assures that the pilot won’t inadvertently cross-control the airplane, potentially leading to a spin. The Ercoupe achieved remarkable success early in its life largely because it was so simple and spin-proof safe.

Along with its distinctive puppy-dog appearance, the Ercoupe offers the pilot a unique flying experience—cruising along with the side windows slid down, arm on the sill and feet flat on the floor, literally steering it with the wheel. Over time, however, the unique interconnected rudder was considered less of an asset, and most Ercoupes flying today have been retrofitted with traditional rudder pedals.

Not many airplanes exhibit such unique features, but even among the Fords and Chevys on the ramp there are still plenty of interesting features to explore. For example, if you lined up every Cessna 172 model that has appeared since 1956, you’d see what appear to be only minor changes in outward appearance. Those incremental changes, however, resulted in some significant changes in handling and performance.

Beginning with the 172M model in 1974, Cessna reshaped the leading edge of the wing, giving it a slight droop by adding a cuff. Cessna also changed the outboard portion of the wing, giving it a bit of twist for a slightly lower angle of attack compared to the inboard panel. The changes to the wing softened the stall characteristics of the 172, making it spin resistant.

The earlier generation of 172s also had another distinguishing feature—flaps that extended to 40 degrees. Those big barn doors were certainly effective in slowing the airplane and enabling a steeper approach angle, but they also had a downside: In the event of a go-around, it was virtually impossible to climb with the flaps fully extended. Cessna decided to limit flap extension on subsequent models to 30 degrees.

If you happen to fly an older 172, sight along the wing for evidence of a droop in the leading edge and washout on the outer panel. If it’s not there, take careful note of how the airplane behaves in a stall, and be sure to maintain yaw control throughout the stall. Check flap extension as well. If they extend to 40 degrees, consider whether you need or want to use all of that aerodynamic braking power on approach.

Like the 172, Piper’s venerable retractable single, the PA-28R Arrow, underwent several minor design changes throughout its long life. (It debuted in 1967, and is still in Piper Aircraft’s new-model lineup as a flight school trainer.) The first Arrow had the distinctive constant-chord wing planform—the so-called Hershey-bar wing—and a four-cylinder, 180-horsepower fuel-injected Lycoming IO-360 powerplant.

Two years later Piper upped the engine to 200 horsepower, and in 1972 the Arrow II appeared with a five-inch-longer fuselage that gave rear-seat passengers about 50 percent more legroom. The cabin entry door also was made wider. The big changes occurred in 1977 with the Arrow III, and again in the 1979 Arrow IV.

The III featured Piper’s new tapered wing, which also was adapted to the fixed-gear Warrior. The new wing had the same airfoil as the earlier constant-chord wing, and the inboard section remained constant chord, but on the outer panel both the leading and trailing edges taper in toward the wing tip. The III has the same wing area as earlier models, but a slightly longer wingspan and much longer ailerons. The longer span and larger ailerons improved roll response and stability, and also increased the service ceiling.

The big change that appeared on the Arrow IV was moving the stabilator to the top of the vertical stabilizer, some eight feet off the ground. The new T-tail sure looked good, and it had some nice effects on handling. Because the stabilator is out of the propwash and downwash from the wing, there is little trim change with changes in power or gear and flap extension. But the T-tail also took a toll on the Arrow’s handling. Pitch forces are much heavier on takeoff rotation and landing than on earlier models, and some pilots believe takeoff distance is longer because of the T-tail.

My recollection is that the early Arrow had slightly better roll and pitch response than later tapered-wing models, and more buffeting to warn of an impending stall. The IV’s T-tail requires some experience to become comfortable with its peculiar traits, which are even more pronounced on the T-tail version of the Piper Saratoga.

If you get an opportunity to fly all versions of the Arrow, or a variety of early and late-model Cessna 172s, or even an Ercoupe (don’t pass that up!), you can decide for yourself how the little things affect the big things we care about in airplanes—handling and performance.