The decision to develop ariane 3 as a successor of ariane 1 was made in july 1979 or almost half a year before the first ariane 1 ever had flown.
Ariane 3 should fulfil the need for a launcher capable of launching 2 tonnes in geostationary orbit. Some of differences between Ariane 3 and ariane 1 was
· New bulb-shaped payload fairing
· New dual launch system (SYLDA)
· Longer third stage with 30% more propellants
· Two 70 tonne solid propellant strap on boosters (PAP)
· Higher pressure in engines of stage 1, 2 and 3
The only difference between ariane 3 and ariane 2 is, that the latter is missing the PAP-boosters. Another curious thing about ariane 3 is, that the first ariane 3 flew almost two years before ariane 2.
The first ariane 3 was launched on august 4, 1984. It was launch number 10 of an ariane rocket. The confidence to the new ariane was so high, that it’s payload was two real communication satellites - ECS-2 for Eutelsat and Telecom 1a for French Television.
The ariane 3 was further developed in to the ariane 4. The last ariane 3 carried the satellite Olympos in to space on July 12, 1989.
Sources and books:
More information about Ariane 3:
(This is only a little selection of the many sources for the model.)
www.capcomespace.net (In french - but simply the best)
Peter Alway: Rockets of the world
Tim Furniss: History of space vehicles
Brian Harvey: Europe's Space Programme: To Ariane and Beyond
William Huon: Ariane une épopée européenne