Effectiveness of a direct lift controller (DLC) for in-flight simulation is discussed. When a model aircraft is operating in backside of power curve, DLC is indispensable. On the basis of this, a quick-moving flaps are installed on the variable stability and response airplane (VSRA) of the National Aerospace Laboratory of Japan. Direct lift capability of the flaps are precisely identified. After tailoring adequate feedback/feed forward gains, a model-following system is constructed to simulate backside-operating models by a mother airplane which is operating in frontside. Included in the paper are the test results of flight verification, showing that a direct lift controller is helpful but not mandatory for simulating frontside-operating models, while it is mandatory for simulating backside-operating models with model-following error of acceptable level. As an application, a flight test result for simulated landing approach in backside range is shown.