Regarding airplane test flights and first flights, don't you have to retract the landing gear of the airplane? As shown in the picture, the Boeing 787 did not retract its wheels on its maiden flight,

Regarding airplane test flights and first flights, don't you have to retract the landing gear of the airplane? As shown in the picture, the Boeing 787 did not retract its wheels on its maiden flight, will not retracting the landing gear affect the flight? Note that this is the first flight, belongs to the test, not the usual passenger flight, so you can't compare the usual commercial flight and the first flight test, this is not the takeoff or landing stage, but in the high altitude level flight

The first flight test in general, the whole process will not be retracting the landing gear, pay attention to see on the way to the 789's trailing edge of the flaps are also fully open, which doesn't mean that the aircraft is about to land, but the first flight is not 100% guaranteed to be able to land, but it's the first time the body will not be able to ensure that the landing gear will not be retracted. But the first flight system is not to ensure 100% operation, so generally will not take up the landing gear, like the A350 first flight test, the first stage of the landing gear are not put away, after a section of the aircraft to maintain high speed cruise, will take up the landing gear, and in the air will do the landing gear retracted test

The maiden flight test looks like ordinary commercial flight is not very different, but the Because of the unknowns and risks involved, it is not exactly the same procedure as a normal commercial flight, so the landing gear down and the trailing edge flaps open are not about to land, but are needed for testing and safety preparations for emergencies that may arise during the flight.