Machines Produced by a Designer who has had Considerable Racing Experience
(Top) A SINGLE-SEATER RACING MONOPLANE, the Percival Mew Gull, seen in the top picture, has set up speed records when flown by the designer, Captain Percival, in the King’s Cup Air Race. The Mew Gull is a development of the Gull, another Percival design, and has a completely enclosed cabin which is streamlined off to fit in with the contours of the fuselage.
(Bottom) THE VEGA GULL, shown in the lower picture, is a four-seater cabin machine. The Gull closely resembles the Vega Gull. Both these models are available with two types of engines giving different performances. With a Gipsy Six, Series II engines, the Vega Gull is claimed to have a top speed of 175 miles an hour.
FEW aeroplanes have had so marked an influence upon the type of machine generally adopted and flown by private owners as the Percival Gull. This aeroplane takes a special place in history because of the way in which it has stimulated high-speed design for light machines, and because it has affirmed the merits of the low-wing monoplane formula.
Designed by Captain E. W. Percival - a pilot of wide experience and one who has set up a great number of records with his own machines - the Gull can be fitted either with the De Havilland Gipsy Six engine of 200 horse-power, or with the lower-powered Gipsy Major. In most details the aeroplane remains the same, but the higher power brings a higher all-round performance.
Outstanding among the features that first strike the observer of a Percival Gull are the excellence of the streamlining and the ingenuity with which the fixed undercarriage has been arranged so that it presents a minimum drag. The Gull is built mainly of wood. The wings have spars made of spruce and plywood, and there are spruce lattice-bracing and former ribs. They are fabric-covered. The Percival split trailing edge flaps (see below) are, aero-dynamically, an important feature.
The fuselage is built of spruce, plywood covered, and the tail unit is the same, with a fabric covering. The undercarriage, is of the cantilever type, and is thus able to dispense altogether with bracing wires and tie rods and, when viewed from-the front, it presents only two narrow legs with faired-in wheels. The cabin is also carefully faired, so that it presents a minimum of resistance while permitting the pilot the best possible outlook. A tail wheel is used. The Percival Gull has a wing span of 36 ft 2-in and is 24 ft 10-in long. The height is 7 ft 4½-in. So that the machine can be kept in a small space by private owners the wings are made to fold. With the wings folded, the span of the machine is brought down to 13 ft 2-in. The wing area is 169 square feet. With the larger engine the tare weight is 1,480 lb; with the smaller engine it is 1,285 lb. The maximum all-up weight (larger engine) is 2,450 lb.
The cabin takes three people, the pilot sitting well in front. Access to the cabin is obtained through the cover, which lifts up and enables those who are using the machine to step in without difficulty. In performance the top speed is especially noteworthy; it is claimed to be 178 miles an hour with the larger engine. At an engine speed of 2,100 revolutions a minute, a cruising speed can be maintained of 156 miles an hour. With the Gipsy Major engine the aircraft’s maximum speed is claimed to be 155 miles an hour; its cruising speed is 133 miles an hour. Its maximum loaded weight is 2,300 lb. The wing loading is 13·25 lb per square foot.
SPLIT TRAILING EDGE FLAPS are an important feature of the Percival Vega Gull. One of them is seen open in this picture. The sections of the wings to which the flaps are attached hinge up to allow the wings to be folded. This is another important feature of the aircraft, because the Vega Gull and the Gull are intended for use by private owners whose garaging space is often restricted, as well as by aircraft operating companies.
In spite of these high top and cruising speeds, the landing speed of the Percival Gull is only 50 miles an hour with full load. The machine can be put down in a distance of 120 yards or, with the Gipsy Major, in a slightly less distance. Moreover, the take-off run is only 195 yards, or 210 yards when fitted with the smaller engine. These exceptionally good figures for a machine with such a high top speed are obtained partly through the agency of the split trailing edge flaps.
These flaps are of long chord; that is, they are deep. When they are operated, they at once increase the drag of the machine, acting as an air brake, and at the same time increase the lift so that the machine can be brought down at a low forward speed and also at a low sinking speed.
Some of the most remarkable world flights have been made with the Percival Gull, including Miss Jean Batten’s flight across the South Atlantic Ocean in November 1935, and they are perhaps the best proof of the machine’s endurance powers. For these flights the aeroplanes were not modified in any way except for the inclusion in the cabin of additional fuel tanks. With the normal number of tanks, the Percival Gull, with the Gipsy Six engine, has a range in still air of 640 miles. With the Gipsy Major engine its range is 760 miles. The extra tanks gave it a range of about 2,400 miles.
Not only has the Percival Gull set up numerous records, but it has also been used extensively for private touring and for air taxi work and special charter. It has been flown by many different pilots in the King’s Cup Air Race, and it has established its reputation as one of the fastest small-size aeroplanes of its time.
Developed from the Percival Gull and closely resembling it in many ways, is the Percival Vega Gull. This is a four-seater monoplane, for which a maximum speed of 175 miles an hour is claimed. The interior resembles in some ways the interior of a saloon car, with the seats arranged in pairs. The front seats are of the bucket type.
A feature of the cabins of the Percival machines is the use of sound-proofing material with leather upholstery, and these, with other devices, reduce engine noise in the cabin to a minimum. Thus the occupants can talk without unduly raising their voices.
High Speed at Moderate Cost
The Vega Gull has a rather larger span than the ordinary Gull, the measurement being 39 ft 6-in; with wings folded the span is 16 feet. The range with standard tanks is 630 miles.
Another machine in the range recently designed and built by Captain Percival is the Q 6. This is an entirely new commercial aeroplane, combining high speed with economical operating costs, and comfortable accommodation for six people.
The Q 6 is a twin-engined aeroplane, the power units being of the Gipsy Six type, Series II, each engine developing 205 horse-power and being fitted with a variable pitch airscrew. The undercarriage of this machine is retractable. Split trailing edge flaps are used, as in the other types, and with these the landing speed is about 55 miles an hour.
The wing construction is cantilever, and the spars are of wood. The fuselage is of plywood box construction, with fabric-covered fairing carried on stringers and formers. Trimming is by tabs on the elevators and rudders. The engines are fitted on the centre section and are underslung to give a clear top line to the wings.
With undercarriage retracted, the top speed of the Percival Q 6 is stated to be 195 miles an hour, and it can cruise at 7,000 feet at 186 miles an hour. Its range at cruising speed is 750 miles.
The Percival Mew Gull is especially suited for racing. It also is a low-wing monoplane, but is of small size and is designed to carry only the pilot. It has a span of 24 ft 9-in and a length of 20 ft 9½-in. The wing area is 88½ square feet. One of the prettiest little machines that have ever taken the air, the Mew Gull is stated to have a top speed of rather over 235 miles an hour with Gipsy Six engine, Series II, having controllable pitch airscrew.
Its range is 860 miles, and it is able to land at the relatively moderate speed of 60 miles an hour. The undercarriage is of the low drag, fixed cantilever type, and there are split trailing edge flaps. The construction is of wood, with the wings plywood covered, as well as the fuselage.
THE LATEST PERCIVAL DESIGN, the Q6, is a commercial aeroplane with luxurious accommodation for six people. The two Gipsy Six Series II engines, each of 205 horse-power, are stated to give a top speed of 195 miles an hour with undercarriage retracted. By the underslung fitting of the engines a clear top line is given to the wings. The landing speed of this aircraft, with flaps in use, is about 55 miles an hour.