Blackburn R.B.1 Iris - 2 Minutes

Blackburn drew on its earlier large-aircraft work when it began the R.B.1 Iris, a very large long-range reconnaissance flying boat designed to Air Ministry Specification R.14/24.

The Iris used three engines to reduce the risk of a forced descent at sea. It could maintain height at full load after one engine failure and continue after losing two, though probably below the preferred altitude.

The Iris's plywood-covered wooden hull and sharp two-step V-bottom helped it accelerate cleanly on the water. A quicker takeoff reduced the time spent at full engine power, saving fuel and limiting strain on the aircraft.