The PIRANHA project was undertaken by ALR as a private venture with the support of Switzerland's industry. The reason for initiating the project was that the development and manufacturing cost of advanced tactical fighter aircraft (F-15, F-18) has risen so high that the number of aircraft which an armed service is able to procure has been reduced to unacceptably low levels. PIRANHA 1 was a subsonic aircraft configuration optimised for the anti-armour and anti-helicopter roles.
PIRANHA 6 was designed to meet the battlefield air superiority and battlefield interdiction roles. These role requirements led to a very small, agile supersonic fighter powered by advanced engines such as the Turbo-Union RB199, EuroJet EJ-200, or Snecma M88. The design works undertaken in the early eighties have been applied by ALR in other projects. An AviationWeek article on the concept, published in 1979 may be found here (login required).
PIRANHA 6 design drawings: