Dave,
I just assumed that using an pump such as a rootes blower would provide very little lift per horsepower(high pressure, low mass). If you are talking about pressure differential on a flat disc shaped surface.... that sounds like a flying saucer.
Sounds like the Avro VZ-9 Avrocar. They invented a unique lift fan system but it never got out of ground effect.
Keep working on the short term lift system, it has to be the most efficient way to VTOL.
slowrotor