As DD said, the main source of excess drag on the Belfast was an area of low pressure under the up-tilted rear fuselage, the “duck’s arse”, created by the airflow in flight. The Belfast freight hold was 18 feet in diameter compared to the C130’s 10 feet and that left a lot of air space to be filled in after the aircraft had gone past. A large bump was fitted under the tail aft of the rear edge of the freight door as a modification and that improved the cruise speed by 35 knots but the whole door couldn’t be modified for cargo loading reasons.
Another problem was caused by the decision for reasons of economy to use the same wings on the Belfast as were designed for the Bristol Britannia but while on the Brit they had to lift a maximum weight of 185,000 pounds they had to lift 230,000 pounds on the Belfast and therefore had to fly at a less than optimum angle of attack. And that meant more drag.
The undercarriage pods were bulkier than the Herc’s because they each held 8 wheels as well as the auxiliary power unit and the ground refuelling connections and control panel.
Am I boring you?
