08/31/2014. Remarks by Johan Visschedijk: "In the autumn of 1917, the British Admiralty called for a single-seat aircraft to carry a Mark VIII torpedo weighing 1,423 lb (645kg), the requirements were embodied in specification N.1B (which was revised as RAF.XXII after April 1918), and since deck-landing was not yet operationally practicable, because of delays in completing the new carriers Argus and Eagle, ditching gear and jettisonable wheels were specified, so that the returning aircraft could be salvaged if unable to reach a shore base after launching its missile. Tenders were submitted by two firms, Blackburn and Short Brothers, and each received a contract for three prototypes to be powered by the Rolls-Royce Eagle VIII engine of 385 hp.

The Short proposal, later named Shirl, was a simple, solid, single-seat two-bay biplane; its fuselage was covered throughout with plywood to resist the effects of temporary immersion, and the wings and tail unit were similar in construction to those of Oswald Short's previous design, the N.2B, with four ailerons, cord trailing edges and folding gear; the wings were of equal span, with square tips and neither stagger nor sweep-back. The engine was neatly cowled, with a frontal honeycomb radiator, and the landing chassis was arranged for release after take off.

At first this was a simple expendable two-wheeled cross-ax1e arrangement, and in this form the first prototype Shirl (serialed N110 c/n S.421) was flown at Grain on May 27, 1918, by Short's Chief Test Pilot John Lankester Parker, climbing to 10,000 ft (3,048 m) with full load in 21 minutes; next day the test was repeated with a four-bladed airscrew but found inferior, so the original two-blader was refitted on May 29.

A few days later Parker delivered it by air to Martlesham Heath, carrying a dummy Mark VIII torpedo; five minutes after take off the petrol-pump drive sheared and he had to make a hurried forced landing, but the trouble was quickly rectified and he was able to take off again; he then found that the throttle control adjustment had been displaced during the repair and that he was unable to close it. As he was determined not to abandon the delivery flight, he stayed on his course and prevented the engine from overspeeding by maintaining a steady climb; this resulted in his arrival over Martlesham at a height of 12,000 ft (3,658), from which he executed a masterly 'dead-stick' landing with the ignition switched off.

On completion of its official tests, with a temporary restriction of the engine to 345 hp, the first Shirl was returned to Rochester for modifications, including incorporation of a small amount of sweep-back to counteract tail heaviness when flotation bags were installed in the rear fuselage. At the same time a new landing chassis was fitted to permit either normal landing or ditching to be selected, irrespective of when the torpedo was launched.

The revised chassis comprised two separate units, each with a tubular skid carrying a pair of wheels on a short cross-axle, a large flotation bag which could be inflated rapidly from a compressed-air bottle and a small hydrovane at the forward end of the skid. The axles were rubber-sprung and could be jettisoned for deck-landing or ditching, and the skids were carried by inclined struts from the bottom longerons and from the wing spars below the inner interplane struts. This arrangement allowed the torpedo to be launched without affecting the landing gear configuration, although jury struts had to be rigged before the wings could be folded.

N110 was completed in this form on July 1, 1918, and underwent satisfactory ditching trials at Grain. The second Shirl (serialed N111 c/n S.422), built to the same overall standard, but with larger ailerons and a fixed tail plane, was dispatched to Grain from Rochester on July 8; it was urgently needed for trials at the Torpedo Aeroplane School at East Fortune, near Dunbar, and Parker hoped to be able to fly it there immediately after a preliminary test flight at Grain.

Unfortunately his first brief handling trial showed N111 to be considerably more tail-heavy than expected, but a rapid consultation with Oswald Short indicated that an increase of tail plane incidence by 4° would put matters right; the tail plane was removed at noon, new fittings were made in the Grain workshops and by four o'clock Parker was ready for a second flight, before which he took on a full load of fuel; he found longitudinal control satisfactory, so flew straight on to arrive at East Fortune 4.5 hours later. He cruised most of the 400 mls (648 km) at 13,000 ft (3,962 m), his only instruments being radiator thermometer, engine tachometer, altimeter, cross-level, fore-and-aft level, an air-speed indicator that did not indicate and a small compass which had not been swung; but he found the Shirl a remarkably stable and untiring machine to fly and arrived with plenty of fuel in reserve, which proved the aerodynamic efficiency of the design.

At East Fortune the Shirl took part in operational torpedo trials along with the Blackburn Blackburd, but in spite of their higher power and weight-lifting ability, both lacked the agility of the Sopwith Cuckoo in taking evasive action after an attack. After these trials N111 went to Martlesham for performance testing on August 24, 1918, and was flown at a gross weight of over 6,000 lb (2,722 kg); although its performance was excellent, it was criticized for not having a tail plane incidence adjuster like N110; consequently N111 was found to be tail-heavy with the torpedo and nose-heavy without it.

The third Shirl (serialed N112 c/n S.423) was not completed till December 11 and was delivered to Gosport early in 1919, being flown back to Eastchurch by Parker on March 28 in a hailstorm; thereafter it was flown at various weights to assess its potential as a civil mail-carrier; for this role a large plywood container of half a ton capacity was slung from the torpedo rack; on April 1 it failed to take off at 7,400 lb (3,357 kg), but three days later it climbed to 5,000 ft (1,524 m) in 25 minutes at 6,762 lb (3,067 kg). It had a revised tail plane adjuster and a new chassis which dispensed with the underwing struts, so that no jury struts were needed for wing folding. Shorts had been invited to quote for a batch of 20 Shirls in February 1919 and promised delivery in April, but the order was not confirmed, and a production contract already awarded to Blackburn for 100 Shirls was also cancelled in favor of more Cuckoos.

The Shirl's stability, fuel economy and weight-lifting ability made it an attractive proposition for an attempt to win the Daily Mail's £10,000 prize for the first non-stop crossing of the North Atlantic, first offered in 1914 and revived in March 1919. It was proposed to convert N112 into a two-seater for this purpose, and a few retouched photographs (one of them shown above) were issued by Short Brothers to show it as such, but the conversion was never made because the Air Ministry refused to lend it for this purpose."