When their father, glider pilot Larry Gehrlein was on an extended vacation, his two sons, Rod and Jay decided to design and build a new glider as a surprise for his return. The resulting GP-1 was designed and built in under a year, between the summer of 1968 and the summer of 1969.
Unlike Larry Gehrlein's earlier Gehrlein Precursor, the GP-1 is an original design and uses no Schweizer Aircraft parts in its construction.
The GP-1 is an all-metal aircraft, with a 151NaN1 wingspan. The wing is of a constant 300NaN0 chord and employs a Wortmann FX-61-184 airfoil. Glide path control is via a set of scissor-type spoilers and air brakes. The design was intended to be simple to construct. Kits were at one time offered for sale with at least five aircraft being completed.
In May 2011 there were still four GP-1s on the Federal Aviation Administration registry.[3]