System and method for the retrieval of a smaller unmanned aerial vehicle by a larger unmanned aerial vehicle

Abstract

A system and method are provided for using a first aircraft to retrieve a second aircraft. The first aircraft is typically larger than the second aircraft. A minimum airspeed of the first aircraft is typically greater than a maximum airspeed of the second aircraft. The first aircraft flies in a substantially circular pattern and extends a tow line, such that the tow line forms a substantially helical shape behind and below the first aircraft. Due to the helical shape, there is at least one point along the extended tow line at which the speed of the tow line is substantially equal to the speed of the second aircraft. The second aircraft can readily latch onto the tow line at that point, thereby minimizing potential damage otherwise caused by differential airspeeds.

What is claimed is: 
     
         1 . A system for using a first aircraft to retrieve at least one second aircraft onto the first aircraft, comprising:
 an extendable tow line attached to the first aircraft, wherein the extendable tow line is configured to be extended from the first aircraft as the first aircraft flies, and further wherein, when extended from the first aircraft as the first aircraft flies along a first path, the extended tow line is configured to form a substantially helical shape behind and below the first aircraft; and   a capture device attached to the at least one second aircraft, wherein
 the capture device is configured to latch each of the at least one second aircraft to the extended tow line from the first aircraft at a point on the tow line wherein a speed of the extended tow line is determined to be substantially equal to a speed of each of the at least one second aircraft. 
   
     
     
         2 . The system of  claim 1 , wherein the first path is substantially circular. 
     
     
         3 . The system of  claim 1 , wherein a ratio of a length of the first aircraft to a length of the at least one second aircraft is greater than or equal to 4:1. 
     
     
         4 . The system of  claim 1 , wherein a minimum first aircraft speed is greater than a maximum second aircraft speed for each of the at least one second aircraft. 
     
     
         5 . The system of  claim 1 , wherein the first aircraft comprises an unmanned aerial vehicle (UAV), and wherein each of the at least one second aircraft comprises a micro-unmanned aerial vehicle (MAV). 
     
     
         6 . The system of  claim 1 , further comprising:
 a catch basket, positioned at or near a bottom of the extended tow line, wherein the catch basket is configured to catch and store each of the at least one second aircraft after each of the at least one second aircraft has been latched onto the extended tow line.