The TST-7 Junior was a development of the TST-1 Alpine self-launching sailplane, with a design goal of producing an aircraft more suited for use as a touring motor glider with docile handling.
The TST-7 is built from wood, with some fibreglass parts. The 12.61NaN1 span, shoulder-mounted, slightly forward-swept wing employs a Wortmann FX 61-184 airfoil and has top-surface air brakes. The landing gear is of tricycle configuration, making ground handling the aircraft much easier than the monowheel gear used on the TST-1. The standard engine was initially the custom-built M 125 of 300NaN0 and later the Rotax 447 of 300NaN0. The aircraft can accept engines of 30to. The cabin width is 580NaN0.[4]
The aircraft was supplied as a standard kit rated at 400 hours for completion and that did not include the powerplant. An Express-Build kit was also available that could be completed in 250 hours. The factory also built some TST-7s as ready-to-fly models that were US$16,250 in 1998 with the M 125 engine and US$17,540 in 2000 with the Rotax powerplant. The plans cost US$350 in 2000.