The SU-1 was developed as an attempt to improve the performance of the Franklin PS-2, by designing new wings for it as a student project. The PS-2's straight 361NaN1 wings were replaced with 461NaN1 gull-wings. Like the original wings, the new wings have two spars, but instead of parallel struts, the new wings use V-struts terminating at a single fuselage attachment point. Jury struts are also used. Like the original wings, the new wings are a wooden structure, covered in doped aircraft fabric covering. The SU-1 retains the PS-2's original steel tube fuselage. The landing gear is a fixed monowheel type.
Testing showed that the Stevens Institute students were successful and the SU-1 has a glide ratio of 17:1, two points better than the PS-2. It also has a slightly higher sink rate of 180 feet per minute versus the PS-2's 150. Gross weight was also increased from 4000NaN0 to 5500NaN0.
About four SU-1s were produced.
In 1983 Soaring magazine reported that two SU-1s were still in existence, one in serviceable condition and one in need of repair.
In April 2011 one remained on the Federal Aviation Administration register.[2]