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Model IV
Model 4-1050 Serial #1400-1722
Introduced at Oshkosh in 1991, the Kitfox Model
4 was a completely new aircraft featuring innovations that enhanced the STOL
abilities, improved flight handling and stability, and increased top speed by 10
to 15%. The Model 4 featured a new higher speed, laminar flow airfoil, new
flaperon design, metal flaperon attach brackets, and a brand new 2:1
differential aileron control system that allows much improved control at full
flaps. The gross weight of the Kitfox Model 4-1050 was the same as the Model 3,
1,050 pounds. The Model 4 is an ideal platform for the Rotax 912 series of
engines but is equally suitable for two-stroke engines.
From a flying standpoint, the Kitfox Model 4-1050 was a genuine attempt to make
the Kitfox handle like a contemporary, certified airplane, without losing the
heritage of agility. It worked. The new airfoil added speed and performance.
The flaperon airfoil, area, placement and movement ratios were changed
significantly. For the first time, the flaperon moving up traveled twice as far
as the flaperon moving down. This is similar to a Piper Cherokee. Rudder
coordination was made much easier. The flaperons continued to be used for climb
and cruise pitch trim, and back pressure is required to maintain approach
speed. While reduction of roll rate was not as pronounced, the use of full
flaperons did reduce the roll by up to 30% and increased the stick loads. The
vertical fin area remained the same as the Model 3, once again a bit small for
the larger engines now being installed. While yaw stability was no longer
neutral, it was not aggressively positive. It would take one more iteration to
get yaw stability to a more contemporary feel.
 
Model 4-1200 (Classic IV) Serial #1723-
The Kitfox Model 4-1200, currently marketed
under the name of the Kitfox Classic 4, is the final evolution of the original
Denney Aerocraft Kitfox design that began in 1984. One of the most successful
kits on the market today, the Classic 4 kit has been sold continuously since
late 1991. The Classic 4 has heavier lift struts and gear legs, as well as
beefed up carry through tubes in the fuselage, to allow for a higher gross
weight than the earlier Model 4 kits. The height of the vertical stabilizer and
rudder was increased by 10 inches, and the rudder depth was increased by 2
inches to allow for improved handling. The Classic 4 is also available in a
short wing Speedster configuration for those wishing more speed and a higher
roll rate.
In 1994, a light weight version of the Classic
4 was introduced with a Rotax 503 as the standard power plant. This airplane,
known as the Kitfox XL, qualified as an ultralight trainer, but did not gain
market popularity. In 2001, an upgraded version of the Kitfox XL was introduced
as the Kitfox Lite Squared and met with instantaneous market success. The
Kitfox Classic 4 remains suitable for both the two-stroke and four-stroke Rotax
912 engine series. Many other engines have been adapted to the Kitfox Classic
4.
 
Not only is the Kitfox Model 4 (Classic 4,
Speedster, Lite Squared) the final evolution of the original Denney Aerocraft
concept in terms of structure and engineering, but it is the best flying of all
the previous versions. The vertical surfaces were increased significantly,
resulting in excellent, positive, yaw stability. The Speedster version of the
Model 4 added aerodynamic enhancements to the empennage, including an electric
trim tab. Speedster modifications can be used on any Model 4 variant. Handling
is smooth and crisp. While rudder coordination is needed, it is much closer to
what most pilots encounter in today’s modern training airplanes.
The higher gross weight and
larger wing fuel tanks cause one to pay attention on landing rollout, but the
much larger vertical tail surface gives you all the control power needed, and
then some. The available electric pitch trim allows the Model 4 (in all its
variations) to be trimmed for hands off flight in almost all normally
anticipated flight attitudes. Many Model 4 aircraft were equipped with the
4-cylinder, 4-stroke, Rotax 912 that produces 80 HP. Model 4 variants are now
turning up with the 100 HP Rotax 912S, resulting in power loadings that are
better than the original, light weight, Model 1. Be prepared for an airplane
that is ready to fly before you are. In 2001, the Classic 4 was packaged as the
Lite Squared and introduced into the ultra light community as a two place, ultra
light trainer. This packaging resulted in the Classic 4/Lite Squared being
adapted to tri-gear in addition to the familiar tail wheel configuration.
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