tdracer,
I hope this doesn't count as thread hijack, but your explanation of the effect of the inlet brought home a point that was eluding me on the AF66 thread. If a fan separated intact from its shaft in cruise, it would at the instant of separation be spinning fast enough to produce significant thrust. Unrestrained, it would tend to pull itself forward through the inlet.
If it have this right, though, once it cleared the inlet (and even if its rotation had not decreased substantially and it had remained undamaged) it would become in effect a UDF turning too slowly to make thrust at cruise speed. So it seems like whatever forward velocity it had relative to the aircraft when it cleared the inlet would be all there was.