A wind propelled vehicle defining a center of gravity. The brush head includes a bottom surface and a body together defining a cavity for receiving the first brushing member. Each paddle deflection limiting member includes a proximal end coupled to the outer surface of the body of the central hub and a distal end opposing the proximal end. The triangular prism includes a first bottom and two opposite first sides. A method of treating a sandstone-containing formation penetrated by a wellbore may also be carried out by forming a treatment fluid comprising an aqueous solution containing a hydrogen fluoride source, ammonium hydroxide and at least one of a polyimide and a polycarboxylate, which is introduced into the formation through the wellbore.