What were the Blackburn B-20's wingtips hiding?

Short answer

The Blackburn B-20's wingtips were actually its floats: they folded outward until they became the wing extremities, somewhat similar to those of the American Consolidated PBY. On water, those two small floats near the tips gave the aircraft stability.

Published: November 5, 2026 · Updated: November 5, 2026 · Edited by Above Ten Thousand · Editorial policy

What were the Blackburn B-20's wingtips hiding?

Rolls Royce Buzzard V-2240-56 (Model H XIV) V-12 Engine - DPLA - 465b7e7eb713ed2689a7790552b96129 (page 1)

Floats that turned into wingtips

The B-20's wing floats folded outward, in a manner somewhat similar to those of the American Consolidated PBY flying boat, until they became the wingtips. On water, the B-20 was essentially a float seaplane: it used a large float under the fuselage for buoyancy and two smaller ones near the wingtips for stability. In flight, the main float retracted upward against the fuselage and locked into a notch to become faired as part of it.

A 1940 experimental aircraft

The Blackburn B-20 was an experimental aircraft that first flew in 1940, seeking to drastically increase the performance of flying-boat designs; Blackburn Aircraft undertook an independent design study based on a patent filed by its chief designer, John Douglas Rennie, for a retractable float forming the planing hull. This configuration gave the correct wing incidence for both takeoff and flight, and in the latter, much lower drag than the deep hulls of flying boats.

Size and powerplant

The aircraft measured 21.23 m (69 ft 8 in) in length and 24.99 m (82 ft 0 in) in wingspan with the floats retracted. It was powered by two liquid-cooled Rolls-Royce Vulture X-24 piston engines, each delivering 1,720 hp (1,280 kW).