October 2012

Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.

Issue link: http://experimenter.epubxp.com/i/84816

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Page 35 of 47

Safety Wire Transition Training for Family IV Airplanes (Nontraditional Configuration and/or Controls). A TC'd airplane example is the Lake amphibian. 1. Defined as airplanes whose ex- ternal configuration is sufficiently different from traditional type certificated (TC'd) single-wing, empennage-mounted tail designs so that they display non-tradition- al handling qualities. Flight control surfaces are different from the typical elevator-aileron-rudder- engine/prop arrangements and/or flight control systems are differ- ent from the typical stick/yoke- pedals configurations. 2. A typical accident scenario would involve a pilot who is unfamiliar with the operation of a crosswind landing gear (e.g. Helio Courier aircraft). When the crosswind gear is "unlocked," the aircraft must be allowed to touch down in a crab. This is so that when the crosswind gear swivels upon touchdown, the aircraft will still track down the runway. (If the aircraft is "de- crabbed" prior to touchdown, with the crosswind gear unlocked, the aircraft will track off the downwind side of the runway, even though its longitudinal axis is parallel to the runway centerline. This is due to the fact that the crosswind will usu- ally provide enough side loads to swivel the landing gear.) Converse- ly, if the aircraft is landed in a crab with the crosswind gear locked, it will ground loop-- just like any other conventional gear airplane. 3. Discussion of transition hazards are as follows: a. The external confi guration of TC'd airplanes follow a standard pattern using a single wing with ailerons (and usually fl aps) and a tail consisting of a vertical and horizontal stabilizer equipped 36 NO. 2/OCTOBER 2012 with trailing edge rudder and elevator. Even though there may be variations on the theme (e.g. a stabilator for the horizontal tail component or a "V-tail" con- fi guration using ruddervators to perform both pitch and yaw functions) all TC'd airplanes will behave in an expected, intuitive, and acceptable manner. b. The innovations presented in the experimental aircraft can include non-traditional confi gurations and controls, canards (Long-EZ), and wing-mounted pusher engine installations (Lake Amphibians) that produce strong thrust-vector effect. Other non-traditional con- fi gurations include fl aperons (i.e. drooped ailerons – Robertson STOL conversions) leading edge slats (Helio Courier), crosswind gear (Cessna 195), differential spoilers c. Issues Specific to Canards are as follows: (i) While canards offer several aerodynamic advantages, they also carry some unique risks. Be- cause a canard lifts upward (rather than downward like conventional tails), it reduces the load carried by the wing (rather than increasing the wing's load). This upward lift characteristic produces improved aerodynamic effi ciency, but also makes its proper aerodynamic design extremely critical. (ii) The canard must be designed to stall before the wing stalls in order to allow a nose-down pitching mo- ment. If the wing stalls fi rst, while the canard is still producing lift, there is no way to lower the aircraft nose and the stall then becomes unrecoverable (i.e. a deep stall). Ad- ditionally, if the canard stalls during Long-EZ (MU-2), and all-moving vertical tails (Mooney M20). Cockpit con- trols may be a yoke, conventional stick, or outboard side-stick. Side- sticks may pivot conventionally, or translate (slide) for pitch while pivoting for roll control. Throttles may be on the left side, right side (or both), in the center, on the fl oor, or on the ceiling (fl ying boats). The obvious hazard in all this is the potential for pilot misuse of the controls due to unfamiliarity with the human-machine interface. the landing fl are, the aircraft will be seriously damaged (or worse). (iii) A canard will typically have a rudder on each swept wing tip, with each rudder only defl ecting outward. This feels natural to the pilot and actually helps minimize adverse yaw. Unlike traditional airplanes, both rudders can be defl ected simultaneously to act as a speed brake. Because the de- fl ected rudders change the air fl ow over the outboard wing sections (which are aft of the aircraft's CG),

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