Patent ID: 6866228
Filing Date: 2005-03-15
Classification: B64D

Abstract:
1. A method for deploying a hose and drogue for aerial refueling of a receiver aircraft from a tanker aircraft, wherein said tanker aircraft includes a refueling system having a hose reel, with the hose wound around the reel, mounted on the tanker aircraft's fuselage such that said reel may rotate in a hose extension direction or in a hose retraction direction, said hose having an outlet end with said drogue affixed to said outlet end, said method comprising the following steps: (a) connecting the hose reel to a variable displacement hydraulic motor's output shaft, said motor having an electro-hydraulic control valve which controls said motor's displacement, the displacement of said motor being approximately zero when said hose and drogue are stowed in the tanker aircraft's fuselage; (b) upon receipt of a deploy command, maintaining said motor's displacement at approximately zero and ejecting the drogue from said fuselage into an air stream and allowing said air stream to pull said drogue so that the hose unwinds from said hose reel and the hose reel rotates in the hose extension direction; (c) sensing the hose's speed; (d) sensing the hose's length which is unwound from said hose reel; (e) while said hose length is beyond a first predetermined length, and while the drogue is not in contact with a probe of said receiver aircraft, setting said motor's displacement so that it causes said hose reel to rotate in the hose retraction direction with the hose winding on said reel and sensing reaction torque on the hose reel (said reaction torque on said hose reel when said hose is being retracted, without the drogue being in contact with said probe, being referred to as “free retraction drag force”); (f) after sensing said free retraction drag force, setting said motor's displacement so that said motor allows the hose reel to continue to rotate in the hose extension direction with the hose unwinding from said reel at a speed up to a first predetermined hose extension speed; (g) when said hose length approaches a second predetermined length, setting said motor's displacement so that the hose extension speed approaches zero; (h) when said hose length reaches said second predetermined length, setting said motor's displacement so that the motor maintains said hose speed at zero; (i) waiting a predetermined time period after said hose speed is zero when said hose length is said second predetermined length and then sensing the reaction torque on the hose reel (said reaction torque on said hose reel when said hose speed is zero at said second predetermined length being referred to as “free trail drag force”); (j) continuing to sense said reaction torque after said receiver aircraft's probe engages said drogue (said reaction torque after said receiver aircraft's probe engages said drogue being referred to as “net drag force”); (k) comparing said net drag force to said free trail drag force, and continuing to set said motor's displacement so that the motor continues to maintain said hose speed at zero until said net drag force is less than a first predetermined percentage of said free trail drag force; (l) when said net drag force is less than said first predetermined percentage of said free trail drag force, setting said motor's displacement so that it causes said hose reel to rotate in the hose retraction direction with the hose winding on said reel at up to a predetermined maximum allowable hose speed; (m) continuing to set said motor's displacement so that it causes said hose reel to rotate in the hose retraction direction with the hose winding on said reel at up to said predetermined maximum allowable hose speed until said net drag force has increased to at least as great as said free retraction drag force multiplied by a factor of K, where K is a predetermined value between approximately 0.2 and approximately 2; and (n) after said net drag force has increased to at least as great as K multiplied by the free retraction drag force, setting said motor's displacement so that the motor  until said hose is maneuvered to a third predetermined length, which is less than the second predetermined length and greater than the first predetermined length, at which time said drogue and hose are in a refueling mode position.