In most cases, twin-engine fighter aircraft were some crotch class are between light combat aircraft, which own superior maneuverability and speed, and languid, more slow-moving and static. They were used as a multi-purpose, being a constituent element in the middle of many aircraft that are designed to perform a variety of combat tasks. As indicated by the history of hostilities, it is advisable for all the army.
The twin-engine aircraft designed by engineer and inventor Leonid Dementievich Kolpakov-Miroshnichenko "Swan Grande" (according to the numbering of the plant — the A-14), was no exception to this rule, because from the beginning it was conceived as a medium bomber far scout, and even a big fighter.
By the beginning of construction — October 1915 — plane "Swan-Grand "was considered the most advanced in the middle of the other twin-engine aircraft. It was built in 1916-1917 for the plant's Russian aircraft and pilot Vladimir Aleksandrovich Lebedev, which was not far from Petrograd.
This company was founded in 1914. Its core competence was the release of single-engine reconnaissance aircraft, which Lebedev produced in significant quantities and more than than any other of the Russian aircraft manufacturers, supplying them up front.
"The Swan-Grand" was perfect other similar machines, "Russian Vityaz" RBVZ-C-18 and RBVZ-C-19 (the creation of the Russo-Balt), "Anatra DE" and "Anadva" (made in the factory Anatry).
During World War II, the project's creator aircraft Kolpakov has developed different versions of the mobile gun installations. The mechanisms of its development in which implemented the different principles of mobility, had wide angles of fire, right up to the firing of anti-aircraft positions. In fact, all the turrets, and the pivot arc arrangements for its construction have been successful and that, in principle, small-sized. Thus, the most well-known and has been used more system having spherical-mobile infantry point on the 2-sectoral gears. It was called a rock unit that was more comfortable to use and the easiest device in the middle of other systems. LD Caps as a developer infantry units worked at Lebedev contracts. Kolpakov not counting affianced work involved in designing aircraft. At the same enterprise Lebedev was designed and built two aircraft.
He made the first airplane was a double spy Kolpakov-1 (K-1), filled with captured SIL engine "Austro-Daimler" (110 hp). Under the scheme of the K-1 was the usual polutoraplan having a movable driven biplane box that is in flight and on the ground can change the angle of the wings to 7 °. In the summer of 1916 to flight test the aircraft knew the fate of virtually all units having a variable angle of the wings. During the first flight with raised wings, he began to climb steeply, and the fall was destroyed. In this regard, decided to discontinue work in this area. During the incident, the pilot MF Gospovsky not injured, the plane was not subject to repair.
In September, the 14th year after the war began, cap turned to the War Office and offered to do battle airplane that was designed to perform air-distant reconnaissance, bombing military targets and enemy troops. Management agencies to have a positive view of this idea, and after consultation with the aviation department has identified the subtleties of the job. The future "Flying cruiser" according to the assignment was to have the "speed of about 150-160 km per hour, the height of the order of 4-5 thousand meters, with a bomb load of 550 to 600 kg …".
Response to the invitation of the inventor only came first of next year, and they, along with spices plant Lebedev was drafted airplane, submitted to the customer and approved in the spring of the 15th year. The main properties of the calculated weight and geometric characteristics, taken in the project were so realistic, that did not change until the end of construction "Cygnus-14." All the differences were not significant and were bullied. The initial focus on a couple of engines each rated at 150 horsepower (mentioned in the job) has become a prerequisite for the fact that the aircraft were selected engines available "Benz". Under this power plant were calculated working draft, please released an album and tactical (observation) model. Once adopted billing and marketing worn temper and not practical, it turned out that the trophy motors can not always be brought to the desired power because for them there were no forms, annotations and other operational documents. The available engines are not the same, or not quite serviceable, needed repairs and long cavity. More 140 horsepower they could give. Allied supplies began equipping cruisers puzzle desired power band simplified. French company "Salmson" proposed landline star-motors with air cooling of the desired power. Specifically chosen for their aircraft. Engines "Benz" willing to put between the internal struts biplane box. For the device under engine mounting rack would have been obtained if the general shape of the diamond bearing points on the upper and lower wings. The engines were installed to sub-horizontal bars that lie at the center of the height of racks. After the substitution of motors Kolpakov was made a decision to build 2-streamlined nacelles, which bring together all the systems and components of propeller groups. Each nacelle collected from pulling two-blade propeller (d = 2,9 m), beginning with his coca engine "Salmson" set in the midship section and the nacelle mounted on the front Y-shaped stands biplane box. In the central compartment of each nacelle installed fuel tank capacity of 420 liters. gasoline which the motor has been divided the firewall. Inside the tail fairing positioned on one more 45-liter tank for motor oil. The tail bearing mount each nacelle, which lie in the plane of the rear wing spars were V-shaped and were composed of duralumin tubes drop-shaped cross-section, similar to the posts Y-shaped, which were hanging sliders. The design of the airplane to transfer traction VMG to a front spar lower wing put the two strut. Front strut, which running tensile was the first bulkhead nacelle axis which is embedded backrest to elongate shaft which transmits to the propeller speed. The rear strut in compression, unloading tail mount gondolas, in other words, a Y-shaped rack wing, which worked on the wriggle when giving gas. So Makarov, more loaded points of the design components were lower wing front spar, which came up and fastened the front landing gear rods (bottom), installed inside the wing reinforced rib. In connection with this, the central part of the lower wing installed reinforced structural elements made stronger (due to the addition of iron linings, fittings and corners) than in other areas of permanent span. On the advic
e of doctors Tymoshenko, the central cell of the box biplane equipped with additional reinforcement of diagonal stretch marks. All the gaps between the uprights and suspension the iron strips diagonally. The end crashes upper wing struts supported on the lower terminations last uprights and supported by kontrpodkosami. Wing structure — wood has a linen tight. The ailerons were only on the upper wing. A two-wheeled chassis had the support legs, which were installed in the plane of the nacelle under the lower wing at a distance of 2150 mm from the axis of the aircraft. Poluvilkami between the tire and the bottom of the fuselage installed Y-shaped struts, which swung around the joints in the body sealing device while driving on rough ground. Multicoil rubber suspension of high power, tightening the front and rear rods landing gear, allowed to move the wheels in the range from 220 to 250 mm in the sediment. Progress through the reduction Pneumatics was insignificant, because the off-design. Wheels (size 900×120 mm) wheels were made of bent ash and light duralumin caps (6×3 mm) covering the spokes of each wheel with 2-sides and attached to the rim with 8 and screws. The tail assembly: keel, rudder and stabilizer, which had deliberately rounded shape of the rear and front edges, including the steering axis compensation.
The fuselage consisted of a 2-piece monocoque made of wood (in Russia for the first time using this scheme for large aircraft). Its front part was the external contour of double curvature, the frame is seven frames and stringers set, four of which have been reinforced by acting as spars. The floor in the cockpit and front hand was postlan on a pair of lower longitudinal bars. Sex in the workplace aerial photograph was priopuschen for greater convenience during aerial photography through the portholes. The rear part of the fuselage also performed as a monocoque construction which through a flanged joint was connected to the head of the fuselage. She recruited from 10 different-sized frames and stringers. Cab rear gunner was arranged at the butt flange. His crew took place using open gaps. Photographer was also lower emergency hatch is used as a window for manual bombing. Armament "Swan-Grand" — three machine guns. One of the design choices foresaw the installation of a 37-millimeter cannon and a 2-machine guns. Management of the tail control surfaces and ailerons — cable. Installation of power communication was made inside the fuselage and wing skin.
In general, the design of an airplane obmyslili carefully and accurately performed during production. "The Swan-Grand" had a decent aerodynamics and this weapon, being pronounced far scout or medium bomber, depending on the payload, destination and options motivated equipment.
But the plane was unable to express themselves in any of the fighting properties of prescribed creators and customers at the design stage.
The construction of the unit began in the middle of 1916 and it lasted until the second half of next year. Began flight tests failed to finish, but we found out that alignment machine is unsatisfactory. Naturally plane for the army was not accepted. Shortcomings which existed in the design, can be removed, but as the War Department to the huge tonnage machines are negative "Swan Grande" is not brought to mass production. In addition, the actions in Petrograd and political action in Russia, was not given the ability to improve aviation equipment. The global collapse that hit the Russian empire, broke aviation "as a class" for 7 years until the 23-24-ies have not started to appear first shoddy amateur light aircraft. The first high-volume aircraft, worthy of universal respect, the country began to emerge only after 10-12 years.
"Great fighter" Kolpakov-Miroshnichenko became a kind of "Swan Song" pre-revolutionary Russian aviation.
Designer himself about himself said only a couple of years. Kolpakov-Miroshnichenko in 1926 made easy bomber LB 2LD. Given plane underwent flight tests, but did not receive future development because there was Tupolev TB-1. Tupolev aircraft in almost all resembled a big fighter, "Swan-Grand."
Flight and tactical characteristics of "Swan-Grand":
Year Release 1917;
Factory designation — L-14;
Powerplant — 2x "Salmson";
Maximum capacity — 2×150 l. s.;
Maximum speed — 140 km / h;
Service ceiling — 4000 m;
Flight duration — 4-5 hours;
Wing area — 91,5 m2;
Take-off weight — 3170 kg;
Empty weight — 2210 kg;
The desired load — 960 kg;
Specific load on the wing — 34.8 kg/m2;
Specific load capacity — 10.6 kg / hp.;
Weight efficiency — 30.2%.