Ed Swearingen's spectacularly fast SX300 was
introduced to the aviation world in 1983, and the
prototype's partially finished airframe was on display
at that year's EAA convention. Swearingen chief test
pilot Bob Thalman made the first flight of N300SX, a
complex airplane with systems still being developed as
construction progressed, on July 11, 1984, and it was at
the EAA convention two weeks later.
Its debut at Oshkosh was quite successful, with a
number of kits sold and a speed record set to underscore
the design's principal reason for being-to go fast!
Thalman turned a lap of 271 mph around the Oshkosh 500
racecourse to set a new NAA/FAI Class C.1b speed record.
The basic concept was to set new standards for
Homebuilt or Amateur Built Aircraft as a dependable,
fast mode of transportation; using all metal
construction and proven techniques to provide an
airframe that was equal to advanced jet aircraft. What a
lot of people came to realize was that while the SX300
is an unbelievably wonderful airplane, it is also
Although initially designed the airplane to
accommodate a number of four- and six-cylinder Lycomings,
Swearingen later standardized on the Lycoming IO-540
with a three-blade Hartzell constant-speed propeller.
The factory prototype had a cowling with conventional
air inlets, but subsequently a new unit with the
now-familiar round inlets was developed.
The Swearingen does good jet-type high-speed
aerobatics. Like the Marchetti, the SX300 flies a lot
like a jet. The airplane is very capable of 280 knots
indicated and a cruise of 240 knots at 18 gph. It's
comfortable, the visibility is great and is a tremendous
Sanders Aeronautics maintain and fly this beautiful
SX300 on a regular basis.