Titanic was divided into four operations (I to IV), consisting of various combinations of dummy paratroopers, noisemakers, chaff (codenamed Window) and SAS personnel. The noisemakers, codenamed Pintails, were attached to each dummy to simulate rifle fire. They also carried a small explosive timed to destroy the dummy and give the appearance of a paratrooper burning his parachute. Four squadrons from No. 3 Group RAF (the special duties squadrons) carried out the drops. No. 138 and No. 161, flying Handley Page Halifaxes and Lockheed Hudsons, as well as No. 90 and No. 149, flying Short Stirlings.