I did the first flight on #33 with the plans windscreen cover and no center cover on the wing gap... All was Ok until I brought the power back to idle on approach to landing at about 100' AGL... The air rushing up from the open fus bottom thru the cab felt like a down ride on an open frame freight elevator - unpleasant... Subsequent flights were with a cover that wrapped from the front spar forward over the wing back to the trailing edge and forward to an end at the rear spar on the bottom of the wing... An opening on the bottom of the wing between the spars has been Ok... My root rib ends are covered... I never bring the power back to idle now until I can see individual blades of grass - in-fact with the 54x20 prop the power is never below 2500 RPM until I'm rotated into 3 point and committed to land... Remember, I'm heavy and LE #33 has never flown below 510 LBS Gross - weight makes a huge difference...