H23D Raven helicopter, Part 1, Main rotorhead H23D Raven helicopter, Part 2, Blade tracking Towing with Vertol helicopters Towing capabilities of the Vertol 44 helicopters (Military H21 Workhorse) 1958 Commercial operations using Vertol Helicopters 1. Opendag Vliegbasis De Peel 2. KLu Helicopters
