Image copyright VIRGIN GALACTIC Image caption Unity is carried aloft by its mothership, Eve

Virgin Galactic has flown its new rocket plane for the first time in a “captive-carry test” above California.

The vehicle, known as Unity, replaces the one that crashed in 2014, killing one of its pilots.

In the captive-carry test, the rocket plane was carried to altitude by its mothership, Eve, to acquire data on aerodynamic performance.

Further such demos will be performed before Unity is dropped and allowed to fire its engine to get into space.

It will be an extended programme, however.

Image copyright VIRGIN GALACTIC Image caption The captive-carry tests gather aerodynamic data

At first, Unity will merely fall away to glide back to a runway.

Only when engineers are happy with the way it is behaving will they introduce in-flight rocket firings, and again these will be introduced progressively - lasting initially just seconds but then building up to the long-duration burns of a couple of minutes needed to make the jump above 100km, the boundary of space.

In blog posts this week, Virgin Galactic has said the return to flying operations is an emotional moment, adding that the lessons learned from 2014, and “meticulous planning and preparation”, have given the company the confidence to move forward.

Image copyright VIRGIN GALACTIC Image caption There will be a long series of flights in the atmosphere before an attempt is made to go into space

Image copyright Virgin Galactic

The first rocket plane, Enterprise, broke up over California’s Mojave Desert on 14 October, 2014.

The accident happened moments after the plane had ignited its engine and just as it was accelerating past the sound barrier.

Co-pilot Michael Alsbury lost his life in the accident. The pilot, Peter Siebold, managed to parachute to the ground but was seriously injured.

A National Transportation Safety Board inquiry stated that the spaceship’s “feathering” mechanism - a system that folds the wings to orientate and slow the vehicle on descent - had been unlocked prematurely.

Intolerable aerodynamic loads tore Enterprise apart at an altitude of more than 50,000ft (15km).

Image copyright VIRGIN GALACTIC

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos