To achieve the necessary reduction in drag and also achieve the design criteria, i.e. non-stop across the Atlantic with 100 passengers, a serious rethink was needed. Bristol had done some initial design work for the aborted Type 159 long-range bomber. This had been a 100 ton bomber with a range up to 5000 miles.

Analysis of the current designs showed that conventional wing mounted engines accounted for 30% of the overall drag, although only 5% was needed for cooling. It became clear to the design team that power plants completely submerged in the wing were thus likely to reduce total drag by 25%, if technically feasible.

The wing would have to be at least as thick as the height of the engine, and coupling several engines side by side to a single airscrew would leave the outer wing free from interference and available for fuel storage. By using this method the larger range required could be easily achieved.