 According to Hill, the Black Prince and Europa were comparable launchers capable to delivering similar performance and roughly the same payloads, the overlap leaving little room for both programmes.However, there was criticisms that Europa would take longer to deliver than the Black Prince launcher for no significant improvement, while suffering from the same core economic problem of being too expensive for scientific satellites while too small for commercial communications satellites.In January 1965, the French thought the initial three-stage rocket design would not be sufficiently advanced to carry the size of payloads required, while another rocket - referred to as "Eldo B" - which featured liquid hydrogen-fuelled second and third stages, came to be viewed as being a superior design, partly due to reduce the cost of the project via the elimination of transition test launchers.