PORTER helicopter (J. Robertson Porter, 9 Gray's Inn Square, London EC)

   Porter exhibited his direct lift machine at Cordingley's Motor Car Exhibition at the Agricultural Hall, Islington in March 1908 and again at the Sports and Travel Exhibition at Olympia in July 1909.
   The design was covered by patent No.21261 /1908 and consisted of two ducted fans in a frame, driven through shafts, gearboxes and a chain drive from the motor mounted on the base. Each fan had four separate stages and was enclosed in a cowl to direct the air pressure downwards. A pusher propeller was mounted on an extension of the horizontal main shaft; a rudder was provided at the rear and was controllable from the operator's station at the front of the machine.
   A similar but smaller machine with a single two-stage ducted fan was also proposed.

   Power: 6hp JAP two-cylinder air-cooled
   Data
   Length 16ft
   Width. 8ft
   Height 14ft
   Weight 200 lb.