Short Scylla


The Short L.17 Scylla was a British four-engined 39-seat biplane airliner designed and built by Short Brothers at the request of Imperial Airways to supplement the Handley Page H.P.42 fleet already in service after Handley Page quoted an excessive price for two additional H.P.42s. They were ordered in 1933.
Imperial Airways used the Scylla for scheduled flights from London to Paris and other European cities. Two aircraft were built, Scylla and Syrinx. Both served with the airline, until its merger into BOAC in 1939, when both were taken out of service the following year, Scylla after being wrecked and Syrinx being scrapped.

Design and development

The Scylla was a land-based development of the Short Kent flying boat, essentially using the Kent's aerostructure above a redesigned fuselage. It was an all-metal biplane powered originally by four Bristol Jupiter XFBM radial engines mounted on vertical struts between the upper and lower planes. The square-section braced-framed fuselage was below the lower wing; the tail had a single vertical stabilizer and a horizontal stabilizer at about one quarter height. The Scylla was originally fitted with a Flettner-type servo tab trim control to ease the forces on the rudder controls. An experimental servo tab on the rudder was tested on G-ACJJ Scylla for a time. Experience gained with the latter possibly contributed to a later patent application submitted jointly by Shorts and Dudley Lloyd Parkes on 7 August 1936.
The main undercarriage had one fixed wheel on each side, mounted on three diagonally-braced struts, one to the upper and two to the lower edge of the fuselage; there was a single tailwheel. Ailerons were fitted to both upper and lower wings.
The engine nacelles were designed to receive Bristol Jupiter, Pegasus or Perseus engines without modification, a far-sighted provision which later enabled e.g. the two inboard Jupiters of G-ACJK Syrinx readily to be replaced with Perseus IIL sleeve valve engines, to test their performance in airline conditions. When Syrinx was re-built, it was fitted with four Pegasus XC engines.

Operators

The two L.17 aircraft, G-ACJJ Scylla and G-ACJK Syrinx, had at different times three different engine configurations between them:
  1. Four Bristol Jupiter XFBM one-row radial poppet valve piston engines of 595 hp each
  2. Two Bristol Jupiter XFBM radial poppet valve radial piston engines of 595 hp and two Bristol Perseus IIL sleeve valve radial piston engines of 540 hp each
  3. Four Bristol Pegasus XC radial poppet valve piston engines of 660 hp each