may I take this opportunity to reiterate my previous comments about lift fans? No-one has ever made them work properly
Not quite sure what you are getting at here. Do you mean aerodynamically, mechanically or perhaps installation wise?
When the X-35B first hovered the CTP of the day was kind enough to call me with the news. I asked how much thrust did you lose out of the rear nozzle with the fan engaged - 6000lb he said. How much thrust did you get out of the fan? 16000lb he replied. The additional 10000lb (approx 25% of the hover weight) was not of course something for nothing but merely indicated the higher propulsive efficiency of a fan compared to a pure jet. But that is just physics. The other advantage of the B configuration is the way the 'cold' fan efflux hitting the ground during a VL stops the hot exhaust from the rear nozzle penetrating forward towards the intakes. (see any IR pics of the event to appreciate that)
The simpler Boeing configuration using the same basic powerplant suffered from less hover thrust and increased risk of recirculation.
Having said all that I personally cannot see the military case for supersonics in a tactical aeroplane - but that is a different topic.
In conclusion the B clearly has lots of problems but I am not sure the fan is central to them.