Have you found yourself wondering how it all works?
[ Note: This discussion relates to certain types of General Aviation aircraft such as Cessna 100/200/300/400 series, the Piper equivalents and Beechcraft products. Examples are the Cessna 172, Piper Warrior, Beechcraft Sierra and other more advanced models of those product lines.]
What are the mechanisms you use to steer/turn your aircraft while in motion on the ground? Have you found yourself wondering how it all works? What good is the control wheel or control stick to steer the aircraft on the ground? – Nothing.
Most of the time, steering is all about your feet. To emphasize this, as a certified flight instructor (CFI), I ask the new student to maneuver the aircraft on the ground by placing their hands under their thighs while I control the power of the engine. They have to use their feet to steer the aircraft using rudder pedals and I admit – this is comical at times. As CFI, I instruct the student to taxi with their hands under their thighs for multiple lessons to overcome the conditioned response to use the control wheel to maneuver the aircraft, a response developed from years of driving a car. Whatever it takes for it to become second nature for the student to “STEER” the aircraft on the ground with their feet. (It should be noted that the control wheel or stick is used to counteract the wind effects while steering on the ground when necessary.)
Tricycle Landing Gear – Front Nose Wheel
Tricycle landing gear aircraft generally have a single forward wheel under the engine and 2 wheels behind it. Some arrangement of mechanical linkage extends from your rudder pedal to the nose wheel in your aircraft. It is usually a metal pedal connected to a metal rod, connected to something that articulates (rotates), then to another rod or a linkage which then applies the force necessary to move the nose wheel in the direction you desire.
Not all General Aviation small aircraft have a physical-mechanical rudder pedal link to the nose wheel. One example is the Aerostar, a twin-engine aircraft where the pilot uses a “Rocker Switch” to steer the front wheel of the aircraft. The switch, located on the console, activates the hydraulic steering attached to the nose wheel. Rick Durden in Sept. 2011 issue of AOPA magazine tells us:
“Nosewheel steering is an electro-hydraulic arrangement controlled via a rocker switch; first taxi attempts by those new to the Aerostar are best compared to a drunk’s excursions on a sidewalk. Should some component of the system fail, taxiing is a painfully difficult affair using differential power and brakes.”
Free Castering Nose Wheels
Other light general aviation aircraft have free castering nose wheels, with no linkage of any kind so the wheel is free to rotate in any direction. Some of the popular aircraft makes and models that have no mechanical links of any kind to the nose wheel are Cirrus S20/22, Diamond DA-40, Vans RV9, Grumman Cheeta, Tiger, Traveller.
Here is a brief video that shows a free castering nose wheel on a Diamond DA-40 aircraft. Notice how aerodynamic the nose wheel and the nose wheel strut are?
The PIC controls (STEERS) the free castering nose wheel aircraft with airflow over the rudder. The amount of air over the rudder is controlled with the use of the engine throttle and Newton’s Three Laws of Motion.
Conventional Landing Gear – The “Tail Dragger”
Conventional Landing Gear aircraft, two front wheels and a single rear wheel, are commonly referred to as a Tail Dragger. So what is different about steering on the ground with this aircraft? Many years ago, the conventional landing gear aircraft was the dominant design and did not have steerable tail wheels. Usually, the aircraft had a tail skid, which could have been a block of wood or a piece of flat metal. To maneuver on the ground (STEER) the PIC had to go through exactly the same process used for free castering nose wheel operation, discussed earlier in this post. There was not any mechanical linkage to the tail skid, however, there was, of course, to the rudder. Later on, a wheel was used in place of a skid with a mechanical link to the tail wheel through the rudder pedals of the aircraft. The big difference between a conventional landing gear aircraft and aircraft with a steerable nose wheel is where the aircraft center of gravity is in relationship to the main wheels of the aircraft. This difference will be the focus of a future post. Conventional Landing Gear aircraft require slightly different skills to takeoff and land, particularly when crosswinds are present.
Landing gear in good working condition are essential to the process the pilot uses to maneuver their aircraft on the ground and takeoff and landing. Common gear configurations found in general aviation aircraft have been discussed here. What kind of landing gear do you have on your aircraft and what issues (if any) have you had with yours? I would love to hear your responses.