A movable support system of an accessory element, configured to be installable on a drone and comprising: • a frame element connectable to the drone fuselage; • a housing module comprising an operating surface configured to couple with the accessory element, said housing module being apt to assume an extracted configuration of maximum encumbrance and a retracted configuration of minimum encumbrance; • rotating connection means of said housing module to said frame element, apt to assume a first position when said housing module is in the extracted configuration and a second position when said module housing is in the retracted configuration; • elastic return means operatively associated with said rotating connection means and connected to the frame element, apt to assume a first rest position when said housing module is in the extracted configuration and a second rest position when said housing module is in the retracted configuration, said first and second rest positions coinciding with respective locking positions of said elastic return means; the configuration of said system being such that: when said housing module is in the extracted configuration and an external stress higher than a predetermined threshold value is applied to it, said rotating connection means is configured to rotate according to a first direction of rotation of an angle (γ); said elastic return means is configured in such a way that, at the aforesaid rotation of said rotating connection means, it passes from said first rest position to an unstable equilibrium position, said elastic return means being further configured in such a way that, when it is in said unstable equilibrium position, it moves to said second rest position, and wherein said rotating connection means is configured to further rotate according to said first direction of rotation up to said second position when said elastic return means moves to the second stable equilibrium position, and said module housing is configured to go into a retracted configuration when said rotating connection means moves to said second position. • a frame element connectable to the drone fuselage; • a housing module comprising an operating surface configured to couple with the accessory element, said housing module being apt to assume an extracted configuration of maximum encumbrance and a retracted configuration of minimum encumbrance; • rotating connection means of said housing module to said frame element, apt to assume a first position when said housing module is in the extracted configuration and a second position when said module housing is in the retracted configuration; • elastic return means operatively associated with said rotating connection means and connected to the frame element, apt to assume a first rest position when said housing module is in the extracted configuration and a second rest position when said housing module is in the retracted configuration, said first and second rest positions coinciding with respective locking positions of said elastic return means; when said housing module is in the extracted configuration and an external stress higher than a predetermined threshold value is applied to it, said rotating connection means is configured to rotate according to a first direction of rotation of an angle (γ); said elastic return means is configured in such a way that, at the aforesaid rotation of said rotating connection means, it passes from said first rest position to an unstable equilibrium position, said elastic return means being further configured in such a way that, when it is in said unstable equilibrium position, it moves to said second rest position, and wherein said rotating connection means is configured to further rotate according to said first direction of rotation up to said second position when said elastic return means moves to the second stable equilibrium position, and said module housing is configured to go into a retracted configuration when said rotating connection means moves to said second position.