Flight, March 1921
THE JACUZZI SEVEN-SEATER MONOPLANE
AN interesting American commercial 'plane has been constructed by Jacuzzi Bros., of Berkeley, California, in which are incorporated several novel features. We give below some particulars of this machine,
which appear in our American contemporary Aerial Age. It is a monoplane having externally braced wings of a comparatively thin section, giving a high maximum L/D at low angles of incidence and high speed. The chord of the wings tapers considerably from root to tip, which enables a uniform wing section to be employed throughout, and at the same time giving a deeper section at the root - a feature possessing advantages from a structural point of view. The wings are of wood construction, fabric covered, and are attached, high up on the fuselage, to a "centre section" which forms the roof of the cabin. They are braced by a streamline sectioned strut under each wing, there being no top bracing. These bracing struts are anchored at their lower and inner ends to the landing chassis tie-rod just aft of the wheels, and the top and outer extremities, which terminate in a Y-head, are attached to heavy metal fittings on the main wing spars at a point about two-thirds out on the wing. The wings are set at a slight dihedral angle, and ailerons are hinged to the outer ends of the rear spars.
The fuselage is of a very clean streamline form, and is, considering the number of passengers carried, of comparatively small proportions. It is built up of six main longitudinals 1 5/8 in. by 7/8 in. and 18 auxiliary members 7/8 in. by 3/8 in., all supported by 14 ply-wood bulkheads. The covering is of 1/4-in. ply-wood. The rear extremity of the fuselage consists of an aluminium casting containing the bearings for the rudder and elevators.
The seats are arranged in three tandem rows, the first seating two - pilot and passenger or two pilots - the second holds three and the third two. In front of the cabin at the leading edge of the wings and on each side of the engine is a window through which a good forward view is obtained. These windows may be cleaned when required from openings provided at the sides. On each side of the cabin are large windows giving an unobstructed view below. Access to the cabin is obtained by a door in the left-hand side of the fuselage, the seats, on that side, of the first and second rows hinging out of the way.
A 200 h.p. L-6 Hall-Scott engine is installed, driving a tractor screw of 8 ft. 2 in. diam. At normal horizontal flight (100 m.p.h.) the engine is required to run at only half-throttle, so that there is an ample reserve of power. Every possible precaution against fire has been taken in the installation of the engine, for instance, the breather pipes, which are of aluminium, are carried up clear above the centre section, and air is taken to the carburettors through air scoops located on the outside of the fuselage. The petrol is carried in tanks mounted in the wings and connected to the carburetors by large copper pipes with flexible couplings. Fan driven pumps deliver petrol to the highest point in each tank, thus maintaining a constant gravity head at all fuel levels. Overflow from the carburettors is conducted outside the fuselage by pipes.
The radiator is mounted high up on the centre section, immediately behind the engine. It is provided with a heavy canvas shutter which can be set at any desired position whilst the machine is in flight. The air-speed venturi tube is mounted above the radiator, out of the air screw slip stream Delco ignition, and two Stromberg carburettors are fitted, the ignition levers, together with the throttle lever, being located in a central position forward of the front seat. The levers operating the radiator shutter are in the cabin roof, within easy reach of the pilot. Dual, or single, stick control is fitted, and the rudder is operated by two sets of interlocked pedals and a double set of cables entirely enclosed within the fuselage.
The landing chassis is especially interesting. The two 750 by 125 wheels are spaced fairly wide - 7 ft. - and are carried on a 2 in. tubular axle sprung by rubber cord to two V-struts. The axle, which has a vertical movement of 6 ins., is located a few inches forward of the apexes of the V-struts and forms the leading edge of an aerofoil-like fairing connecting the axle and the tie-rod to which the wing-bracing struts are attached. The axle being free to move vertically, this fairing pivots, of course, about its trailing edge, which is formed by the tie-rod. A tube connecting the front and rear left-hand struts serves as a step when entering the cabin. The struts are of ash, and are attached to the fuselage by strong pinned ball and socket fittings; the Vs are wire braced transversely. A curved leaf-spring tail skid is fitted.
In actual flight this machine has proved remarkably efficient, as might be expected judging by the clean design throughout. The principal characteristics of the Jacuzzi monoplane are :-
Span 52 ft.
Overall length 29 ft.
Overall height 10 ft. 6 in.
Wing area 400 sq. ft.
Weight empty 1,800 lbs.
Weight fully loaded 3,400 lbs.
Fuel capacity (2 tanks) 80 galls.
Oil capacity 4 galls.
Fuel consumption per hr. 8-9 galls.
Radius of action 900-1,000 miles.
Speed, half-throttle 100 m.p.h.
Speed, three-quarter 125 m.p.h.
Landing speed (full load) 45 m.p.h.
Landing speed (half-load) 38 m.p.h.
Approximate 22,000 ft.