Van's Aircraft RV 12iS, Flight Training Supplement

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Revision: 4 Date:
09/08/20
RV-12iS Flight Training Supplement 2-2
RV-12iS DESIGN FEATURES:
The RV's "traditional" configuration - tractor engine, monoplane, stabilizer in the rear - is an exercise in logic and not
simply a concession to convention. There are many good reasons why light planes have been built this way for
decades, other than the often heard arguments of "entrenched design mentality" from those seeking "technological
breakthroughs.". The bottom line is that this configuration has proven to offer the best compromise resulting in the best
all-around airplane.
Designers often use the term "Mission Profile," which simply refers to the function an airplane is designed to perform.
The RV-12iS mission profile is rather broad
– it is intended to fill nearly all sport flying needs. The profile includes
excellent flying qualities, maximum speed allowed under LSA rules, low stall speed, good visibility, simple assembly for
the home-builder, and economical to own and operate. Meeting all these needs required a design "balancing act
.”
Favoring one need often adversely affects others. An example would be emphasizing cross country cruise performance
by installing extra radios, instruments and upholstery. The weight added would adversely affect all other performance
parameters. This is not a "maybe," it is a certainty.
Given that low cost of ownership is a selling point for any Light Sport Aircraft and is a prime design goal of all RV
designs, the RV-12iS incorporates wings that are easily removable. Because the cost of hangar space is typically the
single largest aircraft ownership expense, removable wings mean that storage costs can be reduced (by sharing of 'on-
airport' hangar space) or eliminated (by storage 'off-airport' at home). This design feature drove other features such as
placement of fuel tank in the fuselage, selection of full-span drooping ailerons (flaperons) which automatically hook-up
upon wing installation, and location of the pitot tube in the spinner. Because the RV-12iS would possibly be trailered to
and from the airport, the wings-removed width had to be sufficiently narrow to allow it to be legally trailered. This limited
the span of the horizontal tail surface to 8 ft. The limited tail span requires that the RV-12iS use a long fuselage placing
the tail surfaces well aft for good control authority.
Seating arrangements vary between the RV designs, depending on the primary mission envisioned. Side-by-side
seating was chosen for the RV-12iS because this arrangement is generally preferred for its primary mission: Sport
Flying. Specific advantages of the side-by-side configuration include equal visibility for both occupants, more-easily
achieved dual control capability, lots of instrument panel space, minimized CG travel for various loading conditions and
a full cowling with room for engine accessories and plumbing. The RV-12iS design places the occupants further forward
than the other side-by-side RV designs. This seating position allows for excellent visibility even in the downward
direction because the wing leading edge is far aft relative to the occupants' eyes. The potential down-side of this 'cab-
forward' arrangement is a CG further forward than desired. The selection of the light Rotax 912 iS Sport engine enables
the RV-12iS to balance well, even with two heavy occupants sitting forward of the wing spar.
We feel that an RV-12iS in its basic form - with fixed-pitch prop, modest instrumentation and avionics, and Rotax 912 iS
Sport engine - represents the best compromise.
Obviously, we could go on and on, covering every design decision, compromise, or concession. However, it should be
apparent by now that every feature of the RV-12iS, whether major or minor, was the end product of much deliberation.
RV-12iS GENERAL DESCRIPTION
AIRFRAME:
The RV-12iS is an all metal, two place, low wing, single engine fixed tricicle gear airplane designed to conform to the
LSA category. The fuselage is made of conventional formed sheet bulheads, stringers and skin (semimonocoque).
A major component of the fuselage is the center section bulkhead that supports the load of each wing spar and main
landing gear. The removeable constant-chord wing is built around a main spar that inserts into the center section
bulkhead.
The empennage consists of a convetional fin, rudder and a stabilator/anti-servo tab.
ENGINE AND PROPELLER:
The RV-12iS is powered by a Rotax 912 iS Sport four-stroke, four-cylinder, horizontaly-opposed, air-cooled with liquid-
cooled cylinder heads, electronic fuel injection, rated at 100 HP/73.5 kW @ 5800RPM. Power to the dual spark plugs is
provided by two independent electronic ignition units. The 912 iS engine is furnished with a starter, two 14-volt
generators and external rectifier-regulators. The propeller is a fixed ground adjustable pitch, 70 inch/177.8 cm diameter,
composite, Sensenich model 2A0R5R70E two blade or optional Sensenich 3Y0R5 C70MY three blade.