Where did the Trislander carry its third engine?

Short answer

On the fuselage's longitudinal axis, atop a lengthened fin: that third engine mounted high on the tail was the most visible change. The Trislander was developed as a larger derivative of the Islander, with the fuselage stretched and reinforced for greater payload capacity.

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

Where did the Trislander carry its third engine?

Britten Norman TrislanderBill Larkins (CC BY SA), vía commons

A larger, derived Islander

Keen to capitalize on the Islander's success, company management chose to develop a larger aircraft derived from its predecessor, in order to make use of common elements and cut development costs. In 1968 the firm flew a stretched variant of the aircraft, known as the BN-2E Islander Super, which was never taken through to certification in favor of a more radical design alternative: the Trislander. To give it considerably greater payload capacity, the Islander's fuselage was lengthened and reinforced substantially.

The third engine, on the fin

The most visible change was the addition of a third engine mounted on the fuselage's longitudinal axis, atop a lengthened fin. In terms of construction, the Trislander resembled the Islander closely enough for both aircraft to share the same final assembly line.

Variants and equipment

Some versions were fitted with auto-feathering propellers and auxiliary rocket-assisted takeoff (RATO) equipment. The III-2 variant carried a 350 lb (160 kg) RATO system.