10/31/2012. Remarks by Walter van Tilborg: "The D-260 was an original design aerobatic two-seat biplane by Nicholas (Nick) d'Apuzzo of Blue Bell, Pennsylvania, USA, and development started with a single-seat aircraft that was built for air show work at the request of Rodney Jocelyn for Lindsey Parsons, the 1950-1952 World Aerobatics champion.

PJ-260. This designation stood for Parsons–Jocelyn Model 260, which was initially the designation for the first aircraft (sometimes referred to as PJ-260M) which was first flown on July 28, 1960 and powered by a 260 hp Lycoming GO-435C-2 engine. This aircraft was followed by several additional PJ-260s which were built with Lycoming O-360, O-435, or GO-435 engines. The PJ-260 formed the basis for the two-seat D-260 variant developed for amateur construction.
D-260 Senior Aero Sport. This was the designation for the basic two-seat model developed for amateur construction. The D-260 appeared in several sub models, mainly differing in the engine installed. This model was dimensionally very similar to the PJ-260.
D-260(1) Senior Aero Sport. Variant fitted with a 250-260 hp Lycoming
O-435 series engine.
D-260(2) Senior Aero Sport. Similar, but with a Continental E-185, O-470, IO-470, OR E225 engine. The first aircraft D-260 to be completed, was built by C.L. McHolland and first flown on July 17, 1965 and represented this variant.
D-260(3) Senior Aero Sport. Similar, but fitted with a 260 hp geared Lycoming GO-435-C2. The first was built by A. Shallbetter. Later aircraft with a Lycoming O-540, possibly re-engined example(s) also appeared.
D-260(5) Senior Aero Sport. A 300 hp Lycoming R680 radial engine. The first example of this model built by Henry Neys.
D-295 Special. Designation for the single-seat aircraft built in 1969 by Ed Mahler, together with L. Webber, with a 280-295 hp Lycoming GSO-480-G1D6 engine. The aircraft was also referred to as the Mahler-Webber D-295 and it differed from the standard D-260 in having a shorter span lower wing and improved ailerons for increased roll rate.
D-201 Sportwing. This model appeared years after the D-260 and was a completely reworked development allowing easier and faster construction methods. It also had reduced weights and a more spacious forward cockpit. Construction of a prototype started in 1977 and this aircraft, built by Larry Stangil, first flew June 1981 with an 160 hp Lycoming IO-320-B1A engine. The D-201 was suitable for engines in the 150-200 hp range and was dimensionally very similar to the D-260.

Production estimates D-260 (10-15), PJ-260 (5-8), D-295 (1), D-201 (1+) = 17-24+ total. The pictured aircraft was built in 1978 by Merrill Vallender of Downers Grove, Illinois (hence the aircraft is also referred to as the Vallender Aerosport) and it received its CofA on May 9, 1980. Presently it is still registered to the builder."