The III V (V for "vertical") was a Mirage III airframe, modified with eight RB.162-31 lift engines (generating 5,400 lb thrust each, or 16:1 thrust to weight!), long-stroke landing gears, and various doors to minimize the undesirable effects of the lift engine exhausts. It was 59 ft long, with a 29 ft wingspan, and weighed about 30,000 lb. It was powered by a SNECMA TF-104 (12,000 lb thrust dry, 20,000 lb in afterburner). Control power was improved over the Balzac, with similarly located control jets at the nose, tail and wingtips.

First hover was achieved on 12 February 1965. The TF-104 was upgraded to a TF-106 for the first supersonic flight. First transition was conducted in March 1966. The second aircraft was fitted with a 10,750 lb thrust Pratt & Whitney TF30. It is the fastest V/STOL aircraft on record, achieving Mach 2.04 on 12 September 1966. The eight engines didn't leave much room for fuel and a visiting US Air Force pilot had to eject, destroying one of the two aircraft when he ran out of fuel during low-speed and hover operations. The other III V was also lost. With the entire fuselage filled with lift engines, the Balzac and the III V seemed to prove that with enough lift engines, any aircraft could be converted to V/STOL. The problem, however, was that there was no room for anything else. The Mirage III V weighed about 3,000 lb over the basic Mirage III, which cost about half the payload and fuel.

Source: AHS V/STOL Wheel