 The main oleo leg fairings were retained, but the main wheel doors and tail wheel doors were removed for the tests.When the undercarriage was retracted, the main gear skis were housed in the space in the lower engine compartment made available by the removal of the fuselage .50 in (12.7 mm) Brownings from the P-51As.The entire installation added to the aircraft weight and required that the operating pressure of the hydraulic system had to be increased from ).