The SABRE engine is designed to be used on a single-stage-to-orbit type of spaceplane. What sort of delay might occur between shutting down the air-breathing operation and switching to a closed-cycle operation (including any spin-down and cooling)?
An exact number may not be known yet, but certainly there must be some design goals. It's not likely to be 1 hour (the craft will lose too much speed and altitude) nor 1 second (there is a substantial configuration change between modes), so the answer will likely be somewhere between those two values.
Are there design goals published, or at least discussed? Is there some way to estimate this based on first principles, current theory, and/or and expected engineering limitations?
Question: Would use of the SABRE engine also require reconfiguration back to air breathing sometimes? Might it have a similar delay? Also, what is likely to be the primary reason or limiting factor for the delay? Heat dissipation?