In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship's hull in the water. Most flying boats have small floats mounted on their wings to keep them stable. All large seaplanes have been flying boats, their great weight supported on their hull.
The Curtiss Models F made up a family of early flying boats developed in the United States in the years leading up to World War I. Widely produced, Model Fs saw service with the United States Navy under the designations C-2 through C-5, later reclassified to AB-2 through AB-5. Several examples were exported to Russia, and the type was built under licence in Italy.
In configuration, these were biplane flying boats powered by a single engine mounted amongst the interplane struts and driving a pusher propeller. The pilot and a single passenger sat side-by-side in an open cockpit. The wing cellule was derived from the Model E landplane and was of two-bay, unstaggered, equal-span construction with large ailerons mounted on the interplane struts and extending past the span of the wings themselves. The earliest examples of this design were built and sold by Curtiss in 1912 without any designation applied to them; the Model F name only coming into use the following year. Confusingly, Curtiss also used the designation Model E to refer to some early machines in this family, although these were quite distinct from Curtiss landplanes that bore this same designation and all but identical to the Model Fs.
Model Fs built from 1918 featured a revised, unequal-span wing that incorporated the ailerons into the upper wing and sponsons on the sides of the hull to improve the aircraft's handling in water. These were known as the Model MF (for Modernised-F), and years later as the Seagull in the post-war civil market.
The Russian Navy purchased two batches of Model Fs in 1913-14 and operated them as part of the Black Sea and Baltic Sea fleets until replaced by the Model K shortly thereafter. In Italy, the Curtiss representative Enea Bossi secured rights for local licence-production of the Type F by the Zari brothers, who built eight examples at their workshop in Bovisia, near Milan. The first of these was demonstrated to the Italian Navy on Lake Como on 22 September 1914.
The Grigorovich M-1 was a single-engine flying boat, designed by Dmitry Pavlovich Grigorovich and manufactured in Russia in 1913.
After repairing a crashed Donnet-Lévêque flying boat, D.P.Grigorovich built his first original flying boat . It differed from the prototype by shorter fuselage of modified shape and wing airfoil similar to one used on Farman-16.
The Grigorovich M-1 is a copy of the French Donnet-Lévêque. The two-seater aircraft was configured so the pilots sat side by side. The M-1 was powered by a Gnome engine and a wooden pusher propeller. There were pontoons mounted at the end of the lower wing to stabilize the aircraft in the water. The M-1 could take off and land in the water. There were lashing points on the fuselage for a dolly allowing land based take-offs..
General performance was satisfactory, but it was obvious that the design needed improvement.
Grigorovich M-2 was an experimental Russian World War I-era biplane flying boat with a single step hull, designed by Grigorovich. It was one of the early flying boat built in Russia.
The M-2 was slightly larger than the M-1. The triangular section rear fuselage was raised from the water, tail was equipped with a skid, often referred to as the "shovel". The lower wings were installed 1m above the hull on the engine support frame.
One example of the M-2 was built and flown several times during the Summer and Fall of 1914. The aircraft crashed on October 10, 1915 damaging it beyond repair.
Grigorovich M-5 (alternative designation Shch M-5, sometimes also Shchetinin M-5) was a successful Russian World War I-era two-bay unequal-span biplane flying boat with a single step hull, designed by Grigorovich. It was the first mass production flying boat built in Russia.
The aircraft designer Dmitry Pavlovich Grigorovich completed his first flying boat (the model M-1) in late 1913, and produced a series of prototypes, gradually improving the design, until the M-5 appeared in the spring of 1915, which was to be his first aircraft to enter series production, with at least 100 being produced, primarily to replace foreign built aircraft, including Curtiss Model K and FBA flying boats.
The M-5 was of a wooden construction, the hull was covered in plywood and the wings and tailplane were covered in fabric. Aft of the step the hull tapered sharply into little more than a boom, supporting a characteristic single fin and rudder tail unit, which was braced by means of struts and wires. It was normally powered by a 100 hp Gnome Monosoupape engine mounted as a pusher between the wings, but some used 110 hp Le Rhône or 130 hp Clerget engines. The pilot and the observer were accommodated side-by-side in a large cockpit forward of the wings, the observer provided with a single 7.62 mm Vickers machine gun on a pivoted mounting.
Most of the M-5s served in the Black Sea or in the Baltic, initially with the Imperial Russian naval air arm and later with both sides in the Russian Civil War. Some remained in service until the late 1920s as trainers, reconnaissance and utility aircraft
The Grigorovich M-9 (alternative designation ShCh M-9, sometimes also Shchetinin M-9) was a Russian World War I-era biplane flying boat, developed from the M-5 by Dmitry Pavlovich Grigorovich.
M-9 was a very successful flying boat, similar to the M-5. It was reliable, was operational on waves over half a meter high, and had above average handling characteristics. The M-9 could be craned to and from the water and ship. The M-9 was also capable of landing on snow without special skis.
The first M-9 was completed in December 1915. The flight tests ere carried out in Baku until January 9, 1916. On September 17, 1916 pilot Ya.I.Nagurskij performed a Nesterov Loop on the M-9, making it the world first hydroplane to perform the maneuvre. Two loops were performed with a passenger onboard.
Unfortunately, the full potential of M-9 was never reliezed. The prototype had egg-shaped engine fairing intended to reduce drag. But on series M-9 it was deleted and never reappeared Numerous requests of pilots and military officials complained about the aircraft's lack of rear defensive armament. Despite the fact that its layout allowed for the addition of a rear gunner's cockpit without any radical changes to the airframe, it never entered production. Several pilots attempted to install a rear-firing machine gun under the wing with real effect. In 1917 many aviators refused to fly the M-9 without an escort. From thn on it flew protected by land-based "Nieuport-17" or "Nieuport-21".
Armament use in individual examples varied. The weapon choices included trainable "Vickers" 0.303 in (7.71mm) machine gun in front cockpit. Sometimes "Gotchkis" or 'Aerlikon' cannons were used. Some observation versions were fitted with radio equiptment.
During Civil War the M-9 was used in cooperation with river combat ships and ocean vessles. One of biggest combat operations the M-9 participated in was the "air defence of Baku" (July-August 1918). Red Army M-9's and M-5's dropped approximately 6000kg bombs and 160kg arrows. The aircraft also carried out photo reconnaissance, artillery spotting and air combat sorties.
Nine M-9s were captured by Finland during the Russian Civil War. One was flown by a Russian officer to Antrea on April 10, 1918. It sank the following day during type evaluation. Eight more were taken over at the airfields at Åland and Turku. The aircraft were used until 1922 by the Finnish Air Force.
The Grigorovich M-11 (or Shchetinin M-11) was a Russian single-seat fighter flying boat designed by Dmitry Pavlovich Grigorovich and built by Shchetinin
Original conceived as a two-seater the prototype M-11 was built in 1916 at the Shchetinin factory in Petrograd. The M-11 was a biplane with a 100hp (75kW) Gnome Monosoupape rotary engine with a pusher propeller strut-mounted below the upper wing. The small number of two-seaters had a poor performance and were only used as trainers, Grigorovich developed a single-seat version powered a 110hp (82kW) Le Rhône engine and fitted with a forward firing machine gun in front of the cockpit. Originally 100 single-seat M-11s had been ordered but this was reduced to 60 as the aircraft had poor handling when landing or alighting on water. The M-11 were operated from snow and ice with twin skis fitted under the forward fuselage and a single ski under the tailplane.
To improve the water handling an improved variant was developed as the M-12 which had a re-designed hull and reduced loaded weight. Although the climb to height was improved the forward speed was 5 mph (8 km/h) less than the M-11 consequentially only a few M-12s were built.
Grigorovich M-15 (alternative designation ShCh M-15, sometimes also Shchetinin M-15) was a successful Russian World War I-era biplane flying boat, developed from the M-9 by Grigorovich.
The M-15 was a smaller version of the M-9 intended to replace the latter, however it was only built in small numbers due to shortage of the more powerful Hispano-Suiza engines. After the summer of 1917 it was mostly used as a trainer.
Two M-15s fell into Finnish hands during the Russian Civil War. The aircraft were abandoned at Âland and Turku. The Russian officer J.Herbert flew the Âland aircraft to mainland Finland and was awarded an officers title in the Finnish Air Force. Only the Âland aircraft was in flyworthy condition. The aircraft was flown until 1919.
The Grigorovich M-24 was a Soviet biplane flying boat in construction during the 1920s.
Dmitri Grigorovich, active during the 20's in the gas plant No.3 "Red Flyers" in St. Petersburg, where he began the development work on the M-24 in April 1922. The design was based on its successful M-9. Some of the differences in the M-24 was dual wings ailerons, and the total area of the hull was changed. THe original design used a 220 hp Renault engine.
The M-24 flight tests began in 1923 and 40 aircraft were produced and delivered beginnng in April of 1924. The flight performance, was unsatisfactory. The pilots and maintenance personnel complained about many defects in the design, resulting in a major redesign of the aircraft. Many construction improvements and the installation of a stronger Renault 260 horsepower motor improved performance.
The designated as M-24 exit plane was first flown in the autumn of 1924. 20 units of this varient were built, which were used until 1926 when the Soviet Navy as a coastal reconnaissance.
The M-24, was the last flying boat designed by Grigorovich. He moved during the redesign of the M-24 exit to the gas plant No. 1, where he designed other aircraft, including the I-2 fighter.