Next step in the Mirage family was the Mirage IV... well, this family is really a mess!
The Mirage IV is more than a twin-engines Mirage III : it's genesis is much more complex.
The Mirage III-01 which flew in november 1956 lacked the Atar-9, shock cones in the air intakes. As a consequence, its top speed was around mach 1.7.
In the early Mirages, every change in the number (I, II, III meant different engine Ie more power)
The plane needed more power...a new engine. So, once again, the name was changed to Mirage IV. Under this name, various engines configurations were studied
- 1 Atar-9 (Mirage IVA /B)
- 1 Super Atar
- 2 atar 9 (Mirage IVC)
and some variants with rocket engines (Mirage IVF)
The Super Atar was never realised.
By lack of funds, the AdA chose the Mirage IVA. Finding that it was quite similar to the Mirage III-01, they named it Mirage IIIA. This plane flew on 12th May 1958, and was the first "real" Mirage III.
But the Mirage IVC was still alive... the AdA wanted it to replace the Vautours (its main competitor was the SO-4060) but once again budget cuts forced the cancellation of this aircraft.
It was nevertheless bringed back to life when De Gaulle "seized" power in may 1958 and decided to develop the nuclear deterrent.. the heavy fighter evolved into a light bomber. This one inherited of the Mirage IVA designation!! It flew in June 1959.
But the atar-9 limited the MTOW to 33 tons, cutting range to 2500km.
As this was clearly insufficient, a scaled-up variant was envisaged. Range, MTOW, wing area were nearly doubled. Of course, the engine power had to follow... as SNECMA was unable to create a 13000 kgp engine, foreign designs were selected.
- PS.13 Iroquois (yes, the Arrow engine...)
- RB-142 Medway (spey ancestor)
The J-75 was declared the winner and the Mirage IVB program started in march 1959. It was abruptly stopped in september because of its foreign engine.
The Mirage IVA was back, the range problem was solved by buying tankers in 1964...