Bonomi BS.2 Balestruccio

BS.2 Balestruccio
Role - High performance sailplane
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1932
Number built - 1

The Bonomi BS.2 Balestruccio (English: House Martin) was an Italian sailplane designed to set records. In 1932 it set a new national endurance record with a flight of over 25 minutes.
Design and development
The Balestruccio was a single seat glider with a high aspect ratio gull wing built in four parts. The two inner panels, straight edged with constant chord and carrying dihedral, joined on top of the fuselage, their extremities braced from the lower fuselage with flat steel V-struts, encased in faired wood to reduce drag and assisted on each side by a pair of jury struts. The upper end of each strut was attached on one of the two wing spars. The outer wing panels were straight tapered, with rounded tips. There were differential ailerons on the outer trailing edges and flaps inboard.
The fuselage of the Balestruccio was hexagonal, with deep, near vertical sides. Its comfortable cockpit was immediately in front of the wing leading edge and was originally provided with a wooden canopy with small side openings, similar to that used on the German DFS Fafnir, but this was later replaced with a more conventional open arrangement which provided better all-round visibility. A single, sprung skid and a tail bumper provided an undercarriage. The fuselage tapered aft to a mid mounted horizontal tail consisting almost entirely of the elevator; although this had straight leading edges, a combination of their slight sweep and the full, rounded trailing edges gave the planform an almost elliptical appearance. There were aerodynamic balances and a large cut-out for rudder movement. As first constructed, the vertical tail was rather similar, with a small fin and a full, deep, curved, balanced rudder which extended slightly below the keel. Later, with the fuselage shortened by one frame or about 700 mm (28 in), the Balestruccio was given a new, angular fin and rudder with straight taper and square tip. Like the old rudder, this was also balanced and deep, though extending only to the keel. The original horizontal tail was retained.
Operational history
The Balesruccio proved to be versatile and efficient and was flown by Vittorio Bonomi and Enrico Rolandi from Mottarone and Campo dei Fiori di Varese. On 18 December 1932 Rolandi flew it for 25.8 minutes, setting a new Italian national endurance record, covering 15.7 km (9.8 mi) and winning the Castiglione Trophy. As late as 1937, it was demonstrating its performance in Asiago.

Specifications
Data from Pedrelli (2011) pp.70-1

General characteristics
Crew: One
Length: 7.55 m (24 ft 9 in) for the shortened aircraft. Zuerl gives 8.33 m (27 ft 4 in)
Wingspan: 18.00 m (59 ft 1 in)
Wing area: 17.14 m2 (184.5 sq ft)
Aspect ratio: 18
Empty weight: 125 kg (276 lb)
Gross weight: 205 kg (452 lb)
Performance
Maximum glide ratio: estimated 24:1
Rate of sink: 0.58 m/s (114 ft/min)
Wing loading: 11.50 kg/m2 (2.36 lb/sq ft)

Bonomi BS.4 Basettino

BS.4 Basettino
Role - Primary Primary glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - c. 1932

The Bonomi BS.4 Basettino (English: Bearded Tit) was a primary glider designed and built in Italy in the 1930s.
Design and development
Like most 1930s primary gliders, the Basettino was a simple, high braced wing aircraft with a forward nacelle and an open frame rear fuselage. Its two spar, fabric covered wing had greater span and aspect ratio than most of its class and had a higher performance airfoil. A straight, constant chord centre section occupied most of the span, with straight tapered outer panels which carried the ailerons and had rounded tips. The wings were supported over the nacelle by a single, central N form strut, with an upright forward member and a sloping rear component. The latter defined the aft end of the nacelle and extended above the wing to form a flat, triangular pylon, from which a pair of landing wires ran to both spars on each side. Flying wires from a point on the lower nacelle directly beneath the tip of the pylon ran to the same positions on the wing underside.
The same sloping rear member of the N-strut was used to join the nacelle to the open rear fuselage. Two pairs of V-shaped steel tube struts were attached to it at the wing trailing edge and at its foot; the first was horizontal, the other upward sloping, and their rear meeting points were used to support the fabric covered empennage. These points were also wire braced from the wing underside. The tailplane, fitted between the end of the horizontal V, had straight edges and constant chord, with rectangular elevators. There was a central triangular fin and rectangular rudder, both extending above and below the tailplane; the rudder worked in a cut-out between the elevators.
The Basettino had a hexagonal section, plywood covered nacelle, with curved upper and lower surfaces. A deep, rubber sprung, wooden landing skid on most of its underside formed its undercarriage. The pilot's cockpit, comfortable though open and without a windscreen, was placed below the wing leading edge.
The first flight of the Basettino was probably in 1932, though all known registration are dated September 1931. The numbers built are also uncertain; Pedrielli reports that there is photographic evidence only for one example, though the rebuilt Italian register records four or five. The aircraft was capable of soaring and its performance was good enough for pilots to obtain their C certificate.

Specifications
Data from Pedrielli (2011) p.77

General characteristics
Crew: One
Length: 5.90 m (19 ft 4 in)
Wingspan: 12.11 m (39 ft 9 in)
Wing area: 15.50 m2 (166.8 sq ft)
Aspect ratio: 9.50
Empty weight: 90 kg (198 lb)
Gross weight: 160 kg (353 lb)
Performance
Maximum glide ratio: 11:1 estimated
Wing loading: 10.30 kg/m2 (2.11 lb/sq ft)

Bonomi BS.5 Ballerina

BS.5 Ballerina
Role - Intermediate training glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1934
Number built - 2

The Bonomi BS.5 Ballerina (English: Wagtail) was a single seat, medium performance training glider designed and built in Italy in the 1930s.
Design and development
The Ballerina was a high, braced wing aircraft. The wing was mounted on a central pedestal and had a central, straight edged, constant chord centre section, built in two parts, which occupied about a third of the span. There were straight tapered outer panels which carried the ailerons and ended at rounded tips. On each side a pair of V-shaped, faired, steel struts braced the outer ends of the centre section to the base of the fuselage.
The fuselage had an hexagonal cross-section with deep, almost upright sides, its upper surfaces curving down over the nose. It was entirely plywood covered. The cockpit was immediately in front of the wing leading edge, placing the pilot's head on the front of the pedestal. A wooden skid with a rubber shock absorbers ran along the underside to form an undercarriage, assisted by a small, faired tail skid. Under the trailing edge the fuselage dropped down from the pedestal then tapered to the rear. The tail surfaces were all straight tapered and square tipped, with almost all of the surfaces moving. Enough fixed fin and tailplane was retained to allow aerodynamic balancing via an inset hinge.
The Ballerina was capable of using both ridge and thermal lift. Pilots could use it to gain their C badge.
Operational history
At least two Ballerinas were built, slightly different in dimensions and dihedral and the reconstructed pre-war Italian civil register suggests there may have been a third. Two spent some time in Egypt, brought in by Italians but operated by the Egyptian Aero Club.

Specifications
Data from Pedrielli (2011) p.79

General characteristics
Crew: One
Length: 6.90 m (22 ft 8 in)
Wingspan: 16.0 m (52 ft 6 in)
Wing area: 16.60 m2 (178.7 sq ft)
Aspect ratio: 15.40
Empty weight: 130 kg (287 lb)
Gross weight: 210 kg (463 lb)
Performance
Maximum glide ratio: 22:1 estimated
Rate of sink: 0.62 m/s (122 ft/min)
Wing loading: 12 kg/m2 (2.5 lb/sq ft)

Bonomi BS.7 Allievo Italia

BS.7 Allievo Italia
Role - Intermediate primary glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1929
Number built - 8 or less

The Bonomi BS.7 Allievo Italia (English: Italy student) was a single seat, primary glider designed and built in Italy in the 1920s.
Design and development
The BS.7 was a primary glider in the Zögling tradition, with high wing and tail, the wings held above the pilot on a flat frame. Its wing and tail surfaces were very close to those of the much copied German glider. It was, though, structurally cleaner and simpler to rig, with most flying wires replaced by faired, steel V-form bracing struts and an empennage supported on a simple box beam rather than an extended central frame.
The extremely simple wing of the BS.7 was built around two spars, one close to the leading edge and the other near mid-chord. The upper ends of the bracing struts were attached to the underside of the spars at about 40% span and to the upper fuselage, at a position directly beneath the forward spar. There was only one bracing wire on each side, running from the top of the forward wing strut to the centre of the upper fuselage just aft of the trailing edge. The fabric covered wing was rectangular in plan apart from the aileron tips, which were obliquely cropped. It was mounted above the fuselage on a trapezoidal frame formed from three struts in a distorted, inverted N shaped arrangement, the rear member sloping shallowly aft.
The fuselage was a triangular cross-section, plywood covered box beam, inclined upwards to place the triangular tailplane at the same height as the wing, strut braced on top of a trapezoidal fin. The fin carried a deep, unbalanced rudder, rectangular except at the bottom where it was cropped to match the bottom line of the beam. It worked in a notch between the two otherwise rectangular elevators, also unbalanced. The completely exposed pilot's seat was on the upper surface of the forward end of the beam, just under the leading edge, where a narrower forward extension carried the rudder bar and, on its underside, the front end of a landing skid that reached below and behind the pilot.
The BS.7 was designed with transportability in mind and, with the wings detached and arranged along the fuselage beam, leading edges up, it could be towed behind a motorcycle on a two-wheeled trailer. Pilots could use it to gain their A and B badges.
Though the first flight was in 1929, the first BS.7s built did not appear on the Italian civil aircraft register until 1932. The number built is uncertain; Pedrielli states three, but eight appear on the reconstructed register.

Specifications
Data from Pedrielli (2011) p.81

General characteristics
Crew: One
Length: 5.56 m (18 ft 3 in)
Wingspan: 11.14 m (36 ft 7 in)
Wing area: 16.70 m2 (179.8 sq ft)
Aspect ratio: 7.50
Empty weight: 90 kg (198 lb)
Gross weight: 160 kg (353 lb)
Performance
Maximum glide ratio: 10:1 estimated
Wing loading: 9.6 kg/m2 (2.0 lb/sq ft)

Bonomi BS.8 Biancone

BS.8 Biancone
Role - Trainer glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - c. 1933
Number built - 6
Developed from - Bonomi BS.7 Allievo Italia

The Bonomi BS.8 Biancone (English: Short-toed Snake Eagle) was a single-seat training glider designed and built in Italy in the 1930s. It was developed from the Bonomi BS.7 Allievo Italia primary glider.
Design and development
The BS.8 Biancone was a higher performance version of the BS.7 primary trainer. The two designs, both high-wing monoplanes, shared a fuselage boom, empennage and wing bracing struts, but the later type had a nacelle with a conventional open cockpit and a pedestal in place of the B.7's simple boom and open girder, together with a new wing of much higher aspect ratio.
The new wing was a wooden two spar structure, largely fabric-covered, like the old. The forward spar was close to the leading edge; from it forward around the edge the wing was plywood covered, forming a torque-resistant D-box; aft the covering was fabric. The rear spar was just behind mid-chord. The central panel, occupying a little under half the span, was straight-edged and had constant chord. Outboard the wing was straight tapered to rounded tips, ailerons occupying all the trailing edge. The centre section was supported by the fuselage pedestal and braced on each side by steel asymmetric V-form struts. These were fixed to the two spars close to the ends of the centre panels and to the fuselage boom directly below the leading edge. It had both a greater span and a lower area than that of the BS.7, increasing the aspect ratio from 7.5 to 12.4.
Like the BS.7, the BS.8 had a fuselage based on a slender, triangular-cross-section, plywood-covered beam, sloping upwards aft from below the leading edge to place the strut braced triangular tailplane at the same height as the wing, on top of a trapezoidal fin. The fin carried a deep, unbalanced rudder, rectangular except at the bottom where it was cropped to match the keel line of the boom. It worked in a notch between the two otherwise rectangular elevators, also unbalanced. The beam now extended to the nose, with a rubber-sprung landing skid attached below it, starting near the nose and reaching back almost to the wing trailing edge. The BS.8 had a conventional, fabric-covered upper fuselage or nacelle on top of the beam from its nose to well behind the trailing edge. The pilot's position was, as before, under the leading edge, but he was now in a "comfortable" cockpit with an "ovoid" seat.
The BS.8 flew for the first time in about 1933, having been first registered in July 1932. Six were built. For a time, one was fitted with floats so that it sat on water with its hull immersed and could be tow-launched behind a motor-boat.

Specifications
Data from Pedrielli (2011) p.83

General characteristics
Crew: One
Length: 6.40 m (21 ft 0 in)
Wingspan: 13.40 m (44 ft 0 in)
Wing area: 14.50 m2 (156.1 sq ft)
Aspect ratio: 12.40
Empty weight: 115 kg (254 lb)
Gross weight: 190 kg (419 lb)
Performance
Maximum glide ratio: 14:1 estimated
Rate of sink: 0.74 m/s (146 ft/min)
Wing loading: 13.1 kg/m2 (2.7 lb/sq ft)

Bonomi BS.9 Bertina

BS.9 Bertina II
Role - Experimental glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1933
Developed from - Bonomi BS.7 Allievo Italia

The Bonomi BS.9 Bertina II was a single seat glider with a layout somewhere between that of a flying wing and the conventional, tail stabilized arrangement. A single example was designed and built in Italy in the 1930s.
Design and development
The BS.9 Bertina II (there seems to be no record of the Bertina I) was an unusual glider, being neither conventionally proportioned nor a flying wing but rather a mixture of both. It was a cantilever monoplane with a very thick wing of low aspect ratio and a cropped triangular plan. The leading edge sweep was about 27° outboard of a short constant chord centre section and there was pronounced dihedral on the wing underside. Long span ailerons occupied almost all the span. A short, simple, cruciform cross-section beam ran back to the empennage, appearing in elevation like a fine boom but from above seen to begin with almost the width of the wing centre section, narrowing rearwards. The tail surfaces were conventional and followed the design of some earlier Bonomi types; the vertical tail was straight tapered and straight angle tipped, with a small fin and large, balanced rudder which extended down to the keel. There was only enough fixed horizontal surface, mounted at the vertical centre of the tail beam, to act as a mounting for the balanced elevators which were shaped similarly to the rudder, though shorter and with a cut-out for rudder movement.
A diagram shows a version of the Bertina II with a fuselage extending conventionally ahead of the wing, though always beneath it. It had a standard single skid undercarriage, with wing tip and tail bumpers. A second form, seen the diagram and also in all the photographs has the glider with a shortened fuselage ending under the wing at around the one third chord point, reducing the overall length to about 3.70 metres (12 feet 2 inches). This version also had vulnerable, lozenge shaped, fixed end plate fins on its tips, extending both above and below the wing, and a double skid undercarriage, forming a sledge-like arrangement held well away from the fuselage and suitable for snow. In both forms the pilot sat in an almost rectangular small, open, unscreened cut-out cockpit in the wing near mid-chord.
The BS.9 flew for the first time in 1933, having been first registered in May that year. Being small, very light, easy to rig in the absence of flying wires and ski-equipped, the Bertina II was very suitable for gliding in mountainous regions from snowy, hard to access fields. Many such flights were reported by Italian aircraft magazines.

Specifications (long fuselage)
Data from Pedrielli (2011) p.85

General characteristics
Crew: One
Length: 4.25 m (13 ft 11 in)
Wingspan: 9.28 m (30 ft 5 in)
Wing area: 12.80 m2 (137.8 sq ft)
Aspect ratio: 6.70
Empty weight: 50 kg (110 lb)
Gross weight: 120 kg (265 lb)
Performance
Maximum glide ratio: 12:1 estimated
Wing loading: 9.55 kg/m2 (1.96 lb/sq ft)

Bonomi BS.10 Ardea

BS.10 Ardea
Role - Single seat competition glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1934
Number built - 1

The Bonomi BS.10 Ardea (English: Great Heron) was an Italian single seat high performance glider, designed and built in the mid-1930s. Only one was built.
Design and development
The BS.10 Ardea was an attempt to improve upon the popular BS.2 Balestrucchio of 1932. Like the Balestruccio, the Ardea was a high gull wing aircraft but with increased span and aspect ratio and less gull dihedral. The two spar wing was built from three panels, the straight edged central one having constant chord. The outer panels straight tapered to elliptical tips, with trailing edges entirely occupied by ailerons. The outer ends of the centre section were braced, as on some other Bonomi gliders, with a pair of faired, asymmetric steel V-struts, mounted on the lower fuselage immediately below the forward wing spar. The wing was mounted over the fuselage on a short, faired pedestal.
The Ardea had a deep sided, hexagonal cross-section fuselage, entirely plywood skinned. Its pilot sat in a small, deep cockpit, head against the front of the pedestal and partly protected from the airstream by the upper fuselage panels, which both lifted off for entry. There was a conventional single skid undercarriage under the forward fuselage aft to the wing trailing edge, with a small tailskid. The fuselage tapered gently to the tail, where a large, roughly elliptical balanced rudder, mounted on a much smaller fin, extended down to the keel. The Ardea's balanced elevators together formed a slender ellipse in plan, though with a cut-out for rudder movement.
The BS.10 flew for the first time in 1934, and was first registered in September of that year. By November it was registered to the Royal Italian Aero Club, Rome. Only one was built.

Specifications
Data from Pedrielli (2011) p.87

General characteristics
Crew: One
Length: 6.79 m (22 ft 3 in)
Wingspan: 19.00 m (62 ft 4 in)
Wing area: 17.60 m2 (189.4 sq ft)
Aspect ratio: 20.50
Empty weight: 140 kg (309 lb)
Gross weight: 220 kg (485 lb)
Performance
Maximum glide ratio: 26:1 estimated
Rate of sink: 0.53 m/s (104 ft/min)
Wing loading: 12.50 kg/m2 (2.56 lb/sq ft)

Bonomi BS.11 Milano

BS.11 Milano
Role - Primary Primary glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1933
Number built - c. 6, including BS.12 Romas

The Bonomi BS.11 Milano and BS.12 Roma were primary gliders designed and built in Italy in the 1930s. Only about six were produced.
Design and development
Plans of the influential German primary glider Zögling of 1926 were sold worldwide and led to many similar new designs. One of its features was a very simple rectangular wing plan; in Italy, Camillo Silva used something similar in at least seven of his designs, the Allievo A and B (1928?) and the Bonomi series BS.7 Allievo Italia (1929), BS.16 Allievo Bonomi (1930), BS.11 Milano, BS.12 Roma (1933) and BS.17 Allievo Cantù (1934). Amongst these, the A and B and the BS.11 and 12 had wire, rather than strut braced wings. These two pairs differed primarily in the pilot's accommodation; the early two had exposed seats and the later gliders open cockpits in full fuselages, though both the rear fuselages and empennages also differed greatly.
Like all these designs, the BS.11 was a simple, high wing aircraft. Its rectangular plan, two spar, fabric covered wings were supported over the nacelle on a single, central, distorted N form strut, with an upright forward member and a sloping rear component. These met the wing at the spars, the forward one almost at the leading edge. The rear member of the N extended above the wing to meet a short, near vertical strut, forming a flat, fabric covered, triangular pylon or cabane, from which a pair of landing wires ran to both spars on each side. Flying wires from a point on the lower fuselage directly beneath the tip of the cabane ran to the same positions on the wing underside. As on all of these low aspect ratio Zögling style wings, the ailerons were short span and broad, with cropped tips forming the wing tips.
The Milano had a rectangular section, plywood skinned fuselage, with an open, unscreened cockpit below the wing leading edge. A wooden landing skid, with deep rubber springing, ran aft from near the nose to the end of the N-frame, assisted by a small tail bumper. The empennage was similar to those of the BS.7 and BS.8, with a strut braced triangular tailplane on a short, broad fin, the latter carrying a constant chord, unbalanced rudder about three times the height of the fin. The elevators were also unbalanced and of constant chord apart from a cut-out for rudder movement.
The BS.12 Roma was similar to the Milano but a little greater in span.
The first flight of the Milano was in 1932. About six Milanos and Romas were built. Designed to be winch launched, they were seen as a suitable aircraft on which to gain a B certificate for a 30-minute flight.

Variants
BS.11 Milano
as described.
BS.12 Roma
Similar but slightly greater span of 20.00m (65ft. 6in).

Specifications (BS.11 Milano)
Data from Pedrielli (2011) p.89

General characteristics
Crew: One
Length: 6.06 m (19 ft 11 in)
Wingspan: 10.92 m (35 ft 10 in)
Wing area: 17.50 m2 (188.4 sq ft)
Aspect ratio: 6.8
Empty weight: 115 kg (254 lb)
Gross weight: 190 kg (419 lb)
Performance
Maximum glide ratio: 12:1 estimated
Wing loading: 11 kg/m2 (2.3 lb/sq ft)

Bonomi BS.14 Astore

BS.14 Astorte
Role - Trainer glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1935
Number built - 1

The Bonomi BS.14 Astore (English: Goshawk) was a two-seat training and aerobatic glider, designed and built in Italy in 1935. Only one was constructed.
Design and development
The Camillo Silva designed Astore first flew in 1935. It was a tandem two seat sailplane intended for training, with the student in the rear, underwing position. This seat could also hold a passenger for pleasure flights at flying events. In addition the Astore was stressed for aerobatics. It was a high braced wing monoplane, with a wing built around two spars and constructed in two parts. Each part had a constant chord central section, and was straight tapered outboard, ending with rounded tips. Ailerons occupied all the trailing edge of the tapered section. The two parts met at and were supported by a low fuselage pedestal; they were braced on each side by a distorted, faired, steel V-strut, with its base mounted on the lower fuselage directly below the forward spar and its two upper ends attached to each of the spars at the outer end of the centre section.
The Astore had a hexagonal cross section, plywood skinned fuselage. The pilot's open, unscreened cockpit was in front of the wing leading edge. The student or passenger sat at the centre of gravity under the wing in a cockpit that formed part of the central pedestal, with side and roof windows. A wooden landing skid with rubber springing, assisted by a small tail bumper served as its undercarriage. The empennage was similar to that of the BS.5 Ballerina, its surfaces straight tapered and square tipped. The balanced rudder was much larger in area than the fin and the horizontal tail was similarly proportioned with only enough tailplane to support the balanced elevators. it was braced just above the fuselage, with large cut outs to allow movement of the lower rudder.
Only one Astore was built.

Specifications
Data from Pedrielli (2011) p.91

General characteristics
Crew: Two
Length: 7.53 m (24 ft 8 in)
Wingspan: 17.60 m (57 ft 9 in)
Wing area: 25.20 m2 (271.3 sq ft)
Aspect ratio: 12.30
Empty weight: 200 kg (441 lb)
Gross weight: 363 kg (800 lb)
Performance
Maximum glide ratio: 22:1 estimated
Rate of sink: 0.70 m/s (138 ft/min) with one occupant, 0.79 m/s (156 ft/m) with two
Wing loading: 14.4 kg/m2 (2.9 lb/sq ft) with two occupants

Bonomi BS.15 Bigiarella

BS.15 Bigiarella
Role - Single seat glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1934
Number built - 3

The Bonomi BS.15 Bigiarella (Italian for 'lesser whitethroat'), originally named the Bonomi BS.6 Bigiarella was a single seat glider, designed and built in Italy in 1934. Only three were constructed.
Design and development
The Bigiarella was a single seat high wing braced monoplane, constructed from wood and fabric. Its fuselage, though conventional, was a new design but otherwise the Bigiarella was very similar to the BS.8 Biancone, using the same wings and support structure. The Biancone, though it had a nacelle housing the cockpit had retained the fuselage boom of its predecessor, the BS.7 Allievo Italia. In contrast, the Bigiarella had a full, rectangular cross section fuselage which was only slightly tapered, the deepest section containing the pilot's open, unscreened cockpit in front of and below the wing's high leading edge. The fuselage was largely fabric covered but the central part containing the wing support structure was plywood skinned. In some photographs the three sloping struts that connected wing and fuselage, a distorted N arrangement most easily visible on the BS.7, were faired in as on the Biancone, but others show them exposed. The new fuselage, deeper at the tail than the Biancone's tailboom, required a less tall fin to maintain the tailplane's position with respect to the rudder but otherwise the empennage was unchanged. A wooden landing skid with rubber springing, deep like the one on the BS.11 Milano and assisted by a small tail bumper served as its undercarriage.
Only three Bigiarellas were built.
Operational history
In July 1934 a Bigiarella set an endurance record of 2 hrs 50 min, flying at Vigne di Valle near Rome.

Specifications
Data from Pedrielli (2011) p.93

General characteristics
Crew: One
Length: 6.82 m (22 ft 5 in)
Wingspan: 13.40 m (44 ft 0 in)
Wing area: 14.50 m2 (156.1 sq ft)
Aspect ratio: 12.40
Empty weight: 115 kg (254 lb)
Gross weight: 190 kg (419 lb)
Performance
Maximum glide ratio: 14:1 estimated
Rate of sink: 0.74 m/s (146 ft/min)
Wing loading: 13.10 kg/m2 (2.68 lb/sq ft)

Bonomi BS.16 Allievo Bonomi

BS.16 Allievo Bonomi
Role - Primary glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1930
Number built - more than 60

The Bonomi BS.16 Allievo Bonomi (English: Student Bonomi) was a single seat primary glider, designed and built in Italy in 1930 and widely used by flying clubs.
Design and development
Despite its seemingly late type number, the BS.16 was one of the first aircraft designed by Camillo Silva after joining the company set up by Vittorio Bonomi in about 1930. Like many primary gliders of the period, its design was strongly influenced by the popular German Zögling. The two types differed chiefly in the detail of their open frame fuselages, the wing and fuselage bracing and the aileron area, though comparisons are not straightforward as there were many Zögling variants, all different in detail.
The BS.16's wings were, like the Zögling's, rectangular in plan apart from clipped aileron tips and mounted without dihedral. The two separate wings were built around two spars, one close to the leading edge with plywood covering forward from it around the edge forming a torsion-resistant D-box. Behind it the wing was fabric covered. One difference from a typical (Segelflugzeubau Kassel) Zögling was that the BS.16's ailerons were increased in length from 40% to nearly 60% of the span. The wings were braced with a pair of struts which ran separately from the lower fuselage frame, slightly diverging, to the wing spars. These removed the need for many of the wing bracing wires and for the triangular pylon of the Zögling to which they were attached.
The forward fuselage frame consisted of two, parallel horizontal members, one above the other. They were connected by a vertical pair of members and two diagonal ones, attached at two points on the lower frame and three on the upper. The rear vertical member was lighter than the forward three uprights, which formed a distorted N; together with the parallel horizontals, this core frame formed a cross braced trapezium. The forward vertical supported the wing at its front spar and the two diagonals met on the rear one. The lower frame extended forwards, with the pilot's seat projecting either side of it immediately ahead of the forward vertical frame. Underneath it, a curved skid was mounted and faired in, forming a long, deep, narrow box, reaching aft to the rear vertical frame. From the trailing edge rearwards the upper frame member was split into two, running parallel to each other and cross braced in the horizontal plane. This provided extra stiffness against sideways flexing and further reduced the wire bracing. Aft of the second vertical member the lower frame sloped upwards, meeting the upper member at the tail. Here, the triangular tailplane was mounted on the upper frame with a trapezoidal fin below. Parallel chord elevators projected behind with a cut-out for the movement of the tall rudder, which was hinged on the extreme frame and was rectangular apart from a cropped under edge. The BS.16 sat with its tail well clear of the ground, so no tail bumper was required, though there was a short aft horizontal extension of the main skid.
Operational history
The Allievo Bonomi was well received by Italian gliding clubs, who used it to take novice pilots to their A certificate. More than sixty were sold.

Specifications
Data from Pedrielli (2011) p.95

General characteristics
Crew: One
Length: 5.64 m (18 ft 6 in)
Wingspan: 10.45 m (34 ft 3 in)
Wing area: 17.80 m2 (191.6 sq ft)
Aspect ratio: 6.10
Empty weight: 110 kg (243 lb)
Gross weight: 185 kg (408 lb)
Performance
Maximum glide ratio: 10:1 estimated
Wing loading: 10.40 kg/m2 (2.13 lb/sq ft)

Bonomi BS.17 Allievo Cantù

BS.17 Allievo Cantù
Role - training glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1934
Number built - more than 100

The Bonomi BS.17 Allievo Cantù (English: Cantù student) was a single seat training glider, designed and built in Italy in 1934 and widely used by flying clubs.
Design and development
The BS.17 was intended to complement the earlier and successful BS.16 primary glider by providing the enhanced performance required to take new pilots to qualifications beyond the A certificate. It used the wings and central support structure of the BS.16 and shared many smaller parts and fittings, but had a new, conventional fuselage in place of the primary's platform, together with different wing struts and empennage.
The BS.17's wings were, like those of the BS.16, rectangular in plan apart from clipped aileron tips. Mounted without dihedral, the two separate wings were built around a pair of spars, one close to the leading edge with plywood covering forward from it around the edge forming a torsion-resistant D-box. Behind it the wing was fabric covered. Centrally, the wings were supported over the fuselage on the same cross braced trapezoidal structure used originally on the BS.16 and later on several other Bonomi gliders. The wings were braced with an asymmetric, faired wooden V strut on each side, attached to the lower fuselage and running to the wing spars at about mid-span.
Its fuselage was a simple rectangular cross section wooden structure skinned with plywood. The single seat, open, unscreened cockpit was immediately below the leading edge. The landing skid was mounted on the front end of a curved, deep, covered frame on the fuselage underside, separating from it aft and rubber sprung well clear towards its end. The fuselage tapered rearwards, where there was a small tail bumper. The tail was different from that of the BS.16; although the same triangular tailplane and parallel chord, cropped tipped elevators were used, they were mounted on top of a low, straight edged fin. A new, large, balanced, angular rudder, hinged at the extreme tail extended down to the keel, operated in a cut-out between the elevators.
Operational history
The Allievo Cantù was well received by Italian gliding clubs, who used it to take novice pilots to their B certificate and gain experience above that level. More than one hundred were sold.

Specifications
Data from Pedrielli (2011) p.73

General characteristics
Crew: One
Length: 6.37 m (20 ft 11 in)
Wingspan: 10.50 m (34 ft 5 in)
Wing area: 17.80 m2 (191.6 sq ft)
Aspect ratio: 6.20
Empty weight: 125 kg (276 lb)
Gross weight: 205 kg (452 lb)
Performance
Maximum glide ratio: 16:1 estimated
Wing loading: 11.20 kg/m2 (2.29 lb/sq ft)

Bonomi BS.18 Airone

BS.18 Airone
Role - Training glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1936
Number built - 1

The Bonomi BS.18 Airone (English: Heron) was a single seat training glider, designed in Italy in 1936. Only one was built.
Design and development
The Airone was an attempt to produce a training glider similar to the BS.8 Biancone but with a better glide ratio. It used the wings of the Biancone but had the more refined fuselage of the BS.10 Ardea. The wing bracing and the empennage was new.
The wing was a wooden two spar structure, largely fabric covered. The forward spar was close to the leading edge; from it forward around the edge the wing was plywood covered, forming a torque-resistant D-box; aft the covering was fabric. The rear spar was just behind mid-chord. The central panel, occupying a little under half the span, was straight edged and had constant chord. Outboard the wing was straight tapered to rounded tips, ailerons occupying all the trailing edge. The centre section was supported by a low fuselage pedestal and braced on each side with a parallel pair of steel struts. These were fixed to the two spars close to the outer ends of the centre panels and to the lower fuselage.
The Airone had a deep sided, hexagonal cross-section fuselage, entirely plywood skinned. Its pilot sat in a small, deep cockpit, head against the front of the pedestal and partly protected from the airstream by the upper fuselage panels, which both lifted off for entry. There was a conventional single skid undercarriage under the forward fuselage aft to the wing trailing edge, with a small tailskid. The fuselage tapered gently to the tail, where the horizontal surfaces, braced and straight edged but with elliptical tips were mounted on top of a short fin. The elevators used a thick aerofoil for efficiency and had a cut-out for the balanced rudder. This was large, extending down to the keel with straight edges and rounded corners.
The BS.18 Airone first flew in 1936 but only one was built.

Specifications
Data from Pedrielli (2011) p.97

General characteristics
Crew: One
Length: 6.79 m (22 ft 3 in)
Wingspan: 13.37 m (43 ft 10 in)
Wing area: 14.50 m2 (156.1 sq ft)
Aspect ratio: 12.40
Empty weight: 108 kg (238 lb)
Gross weight: 183 kg (403 lb)
Performance
Maximum glide ratio: 18:1 estimated
Rate of sink: 0.76 m/s (150 ft/min)
Wing loading: 12.60 kg/m2 (2.58 lb/sq ft)

Bonomi BS.19 Alca

BS.19 Alca
Role - Motor glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1936
Number built - 1

The Bonomi BS.19 Alca (English: Auk) was a single seat, tractor configuration motor glider, designed and built in Italy shortly before World War II. It had an unusual retractable undercarriage used only for take-offs. Only one was built.
Design and development
In the mid-1930s some glider designers were beginning to think about incorporating an engine, to form a self-launching aircraft. One of the first of these, the Carden-Baynes Auxiliary flew in 1935. It was very clearly primarily a glider, particularly when its engine and propeller were folded away into the fuselage, an operation possible in flight. The BS.19 Alca of 1936 was closer to a high aspect ratio light aircraft, with no provision of a foldaway propeller. It was the first powered aircraft designed by Camillo Silva for Aeronautica Bonomi. The Alca, a single seater, was powered by a small flat twin engine of unknown make but producing between 15 kW (20 hp) and 19 kW (25 hp).
The Alca's cantilever mid-mounted monoplane wing was built in three parts around a box front spar and a second rear spar. There was a short centre section, only about 10% of the span and integrated into the fuselage, plus two outer panels. The wing plan was strongly straight tapered, largely on the trailing edge, ending in elliptical tips; there was also strong taper in thickness. Covering was a mixture of plywood and fabric. Long ailerons occupied more than half the span.
The Alca's flat sided fuselage was deep from the nose to behind the wing trailing edge where the underside swept upwards, producing an almost boom like rear fuselage. The pilot's open cockpit, fitted with a small windscreen, was placed just ahead of mid chord between the spars. The upper fuselage line was almost flat and the little twin cylinder engine was high in the nose with its cylinder heads exposed for cooling. At the rear the empennage was conventional, though in glider fashion the straight edged fixed surfaces were small in area compared with the control surfaces. A tailplane braced from both above and below was mounted on the fin just above the fuselage; together with its balanced elevator it had a tapered, round tipped plan, with a cut-out for movement of the straight edged, though rounded, balanced rudder which extended to the keel. The Alca had a conventional glider type, rubber sprung landing skid plus tail bumper but it also had an unusual wheeled undercarriage for take-off. This featured a wheel on each side mounted on a half axle attached to the lower fuselage longeron and a vertical shock absorbing leg to the wing. After take-off, this was retracted and not used again until the next departure.
Data on the Alca's performance under power have survived, but not on its gliding characteristics beyond a comment that they were excellent, as was the handling. Only the prototype was built.

Specifications
Data from Pedrielli (2011) p.99

General characteristics
Crew: One
Length: 6.90 m (22 ft 8 in)
Wingspan: 14.50 m (47 ft 7 in)
Wing area: 17.80 m2 (191.6 sq ft)
Aspect ratio: 12
Empty weight: 200 kg (441 lb)
Gross weight: 280 kg (617 lb)
Powerplant: 1 × Unknown type of air cooled flat twin, 15 kW (20 hp) or 19 kW (25 hp)
Propellers: 2-bladed
Performance
Maximum speed: 120 km/h (75 mph, 65 kn)
Stall speed: 48 km/h (30 mph, 26 kn)
Wing loading: 17.80 kg/m2 (3.65 lb/sq ft)

Bonomi BS.20 Albanella

BS.20 Albanella
Role - Performance glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1939
Number built - 1 or 2

The Bonomi BS.20 Albanella (English: Montagu's harrier) was a performance sailplane designed and built in Italy in the late-1930s. Rather little is known about it; either one or two were constructed.
Design and development
The BS.20 Albanella is not well documented and the little that is known about it comes a hand-written note on its general characteristics, a number of photographs taken at Milan in the mid-1930s and a sketch on a postcard. It may have been intended for aerobatics.
The Albanella was a cantilever shoulder wing monoplane with a swept straight tapered wing which ended in rounded tips. All the sweep was on the leading edge. Long ailerons occupied more than half the span. As elsewhere on the BS.20, the wing covering was a mixture of plywood and fabric. Its oval cross-section fuselage was conventional at the front, with the pilot's open cockpit just ahead of the leading edge with an eye-line over the upper wing. The main landing gear was a sprung ventral skid stretching from near the nose to below the wing trailing edge. The dorsal line was straight in elevation but immediately aft of the wings the lower ventral line turned quickly upwards and the fuselage became much finer, almost producing a pod and boom form. Horizontal rear surfaces were elliptical in plan. The vertical tail was straight tapered to a rounded tip with a rudder extending down to the keel and operating in an elevator cut-out.
Photographs suggest there were two somewhat different versions, though whether as a result of modification or the construction of a second prototype is not known.
The Albanella was one of two Italian representatives at the Berlin Olympic games of 1936 (the other was the Teichfuss Orione), part of a successful demonstration to establish gliding as an Olympic sport (Gliding at the 1936 Summer Olympics).

Specifications
Data from Pedrielli (2011) p.101

General characteristics
Crew: One
Length: 6.06 m (19 ft 11 in)
Wingspan: 15.25 m (50 ft 0 in)
Wing area: 15.20 m2 (163.6 sq ft)
Aspect ratio: 15
Empty weight: 185 kg (408 lb)
Gross weight: 270 kg (595 lb)
Performance
Maximum glide ratio: 24:1
Wing loading: 17.80 kg/m2 (3.65 lb/sq ft)

Bonomi BS.22 Alzavola

BS.22 Alzavola
Role - Motor glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1934
Number built - 1
Developed from - Bonomi BS.15 Bigiarella

The Bonomi BS.22 Alzavola (English: Teal) was a training motor glider, intended to acquaint capable glider pilots with the characteristics of powered aircraft. The sole example was designed and built in Italy in the mid-1930s.
Design
The BS.22 was evolved from the earlier Bonomi BS.15 Bigiarella glider, though with the addition of a small flat twin engine which drove a pusher propeller. It also had a retractable wheeled conventional undercarriage and a quite different tail. Intended as an inexpensive aircraft, it was Bonomi and Silva's second and last motor glider, the other being the Bonomi BS.19 Alca. The Alzavola was intended to introduce glider pilots with C or B certificates to the complications of powered aircraft. In particular, as well as the retractable conventional undercarriage it had a standard glider landing skid so new pilots could take-off on wheels, retract them and land on the skid in the way they were used to. After becoming familiar with the Alzavola they could put the wheels down before landing.
The wing had a constant chord, unswept central section and straight tapered outer panels with rounded tips. The outer panels' trailing edges were entirely filled with the ailerons. The centre section was supported over the fuselage on a pedestal, which also supported the small flat twin engine slightly above the wing surface, neatly cowled but with its cylinder heads exposed for cooling. Its pusher propeller rotated in a rectangular trailing edge cut-out, at about 70% chord. On each side an asymmetric V-strut, mounted on the lower fuselage longeron immediately below the forward wing spar, supported the outer ends of the centre section, joining its two spars.
The fuselage was flat sided and essentially rectangular, though there was decking to fair in the open cockpit, which had a small windshield, and a dorsal fairing to merge the rear of the pedestal to the tail. Under the cockpit, where the fuselage was deepest, there was a typical glider landing skid. Its conventional undercarriage had two balloon tyre mainwheels, each mounted on V-form split axles attached to the skid and with a shock absorbing strut fixed to the lower longeron. At the rear there was a tailskid. Both tail surfaces were straight tapered and straight cropped. Both rear control surfaces were much larger in area than their fixed counterparts and balanced; the rudder extended to the keel and operated in an elevator cut-out as the tailplane was mounted on the fin just above the fuselage, braced from above and below.
The Alzavola could take off under its own power but could also be launched, with its wheeled undercarriage retracted or removed, by bungee cord, winch or air-tow.

Specifications
Data from Pedrielli (2011) p.103

General characteristics
Crew: One
Length: 6.80 m (22 ft 4 in)
Wingspan: 12.43 m (40 ft 9 in)
Wing area: 15 m2 (160 sq ft)
Aspect ratio: 10.30
Empty weight: 180 kg (397 lb)
Gross weight: 295 kg (650 lb)
Powerplant: 1 × Unknown type of air cooled flat twin, 13 kW (18 hp) or 19 kW (25 hp)
Propellers: 2-bladed
Performance
Maximum speed: 100 km/h (62 mph, 54 kn)
Stall speed: 50 km/h (31 mph, 27 kn)
Wing loading: 19 kg/m2 (3.9 lb/sq ft)

Bonomi BS.24 Biposto Roma

BS.24 Biposto Roma
Role - Dual control trainer glider
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - 1935
Number built - 6

The Bonomi BS.24 Biposto Rome (English: Rome two-seater) was an Italian dual control trainer designed for club use. Six were built in the mid-1930s.
Design and development
Camillo Silva designed numerous gliders for Aeronautica Bonomi, but only two of them, the BS.14 Astore and the Biposto Roma were two seaters. When the company started out in 1931, early glider training used single seat primary gliders and the absence of an experienced pilot on board resulted, in England at least, in many injuries and closure of gliding clubs. By 1935 Italian gliding clubs felt a need for dual control aircraft, with good enough performance to take pupils to their C certificates. They were the Biposto Roma's target market.
Despite the partial overlap in names between the Biposto Roma and the earlier BS.12 Roma they had little else in common. In plan, about half of the span of the BS.24's wing was unswept and had constant chord; the outer panels were straight tapered to rounded tips. Ailerons occupied all the trailing edges of these outer panels. There was no dihedral. The wing centre was mounted high above the fuselage on steel struts; in several of his designs Silva had used a cross braced trapezoidal frame for this purpose but the second cockpit, placed at the centre of gravity (c.g.) under the wing, precluded this and instead there were vertical struts behind each cockpit, one to each wing spar and a third, leaning strut from the rear spar. The ends of the spars of the central, constant chord panels were braced to the lower fuselage longerons, directly under the forward wing spar, by asymmetric V-form, faired steel struts.
The Biposto Roma's fuselage was a wooden, rectangular cross section structure, skinned with plywood. Its two cockpits, both open and unscreened, were in tandem. If the aircraft was flown solo it was piloted from the font seat; the occupation or otherwise of the rear cockpit left the trim little changed as it was on the c.g. Under the fuselage a rubber sprung wooden landing skid ran from forward of the cockpits to well aft of the wing trailing edge. The tailplane was triangular, mounted on top of a short, trapezoidal fin and braced to the top of the fuselage. Its elevators had parallel chord and a central cut-out for the rudder, as this, hinged on the fin's trailing edge, was about twice as high as the tailplane. The rudder was straight edged and reached down to the keel; above the tailplane, it had an aerodynamic balance on its upper leading edge.
Operational history
At least five Biposto Romas were used by the Poggio Renatico gliding school.

Specifications
Data from Pedrielli (2011) p.105

General characteristics
Crew: Two
Length: 7.21 m (23 ft 8 in)
Wingspan: 14.18 m (46 ft 6 in)
Wing area: 21 m2 (230 sq ft)
Aspect ratio: 9.60
Empty weight: 160 kg (353 lb)
Gross weight: 310 kg (683 lb)
Performance
Maximum glide ratio: 16:1 estimated; 9.0:1
Rate of sink: 0.85 m/s (167 ft/min) , flown solo
Wing loading: 14.80 kg/m2 (3.03 lb/sq ft)

Bonomi BS.28 Alcione
(Bonomi BS.28 Aerodinamico)

BS.28 Alcione
Role - Competition sailplane
National origin - Italy
Manufacturer - Aeronautica Bonomi
Designer - Camillo Silva
First flight - c. 1938
Number built - c. 4

The Bonomi BS.28 Alcione (English: Halcyon or Kingfisher), sometimes known as the Lombarda BS.28 Alcione, was a single seat competition sailplane designed and built in Italy in 1937-8. About four were completed, with two more or less refined fuselages.
Design and development
The Alcione was the last of many gliders designed by Camillo Silva at Aeronautica Benomi, as the latter was taken over in 1937 by Aeronautica Lombarda. The change of ownership led to the Alcione being referred to as both a Bonomi and a Lombarda. Silva designed at least one further glider for Lombarda, the AL-3 which was one of two Italian competitors in the 1939 Olympic Sailplane Competition of 1939.
The Alcione was a refined sailplane in its day, designed in collaboration with the Polytechnic University of Milan. It was a cantilever mid-wing monoplane, its wing built around a single spar at about one third chord. Forward of the spar the wing was plywood covered, forming a torque resisting D-box; elsewhere it was fabric covered. In plan the wings were straight tapered to rounded tips. The whole trailing edge of each wing was moveable, the inner third acting as camber changing air brakes and the rest as differential ailerons. Spoilers of the early, single action Centro Volo a Vela (CVV) type were mounted on the upper wing surface immediately behind the spar and at about one quarter span.
Two different fuselages were built for the Alciones. Both had the same general form, deep under the cockpit which was placed forward of the wing leading edge under an enclosing canopy. There was a short landing skid, ending aft at a semi-recessed wheel at about mid chord. However, one fuselage type had a hexagonal cross-section and the other was better shaped aerodynamically as an ovoid. The latter was lower along the dorsal line, so the other's glazed cockpit cover was lengthened aft with a ply covered extension including small side windows. The lower line also required the addition of a very short pedestal for the tailplane, directly mounted onto the hexagonal fuselage. The horizontal tail was straight tapered and round tipped, placed with its trailing edge in line with that of a narrow fin so that no cut-out for rudder movement was needed. On the ovoid fuselage version with its small pedestal the fin reached only about halfway to the top of the rudder, allowing the inclusion of an aerodynamic balance. On the other fuselage the fin continued upwards to the rudder tip. The rudder itself was broad and D-shaped. There was a little tail bumper on the fuselage keel at the rudder's foot.
The ovoid fuselage version became known as the B.28 Aerodinamico.
The Alcione dates from either 1937 or 1938, with registration dates supporting the latter. Images identify three examples and the register a fourth.
Operational history
An Alcione took part in the Asiago Gliding Competition of 1938.

Specifications
Data from Pedrielli (2011) p.107

General characteristics
Crew: One
Length: 6.55 m (21 ft 6 in)
Wingspan: 14.50 m (47 ft 7 in)
Wing area: 14 m2 (150 sq ft)
Aspect ratio: 15
Empty weight: 160 kg (353 lb)
Gross weight: 254 kg (560 lb)
Performance
Maximum glide ratio: 22:1 estimated
Rate of sink: 0.75 m/s (148 ft/min)
Wing loading: 17.50 kg/m2 (3.58 lb/sq ft)