Naleszkiewicz JN 1

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Naleszkiewicz JN 1
JN-1.jpg
RoleExperimental tailless sailplane
National origin Poland
ManufacturerCWL Dęblin
DesignerJarosław Naleszkiewicz
First flight23 July 1932
Number built1

The Naleszkiewicz JN 1 was an experimental tailless sailplane designed in Poland to explore the aerodynamic properties of a proposed powered tailless aircraft. It proved hard to fly and a crash led to its abandonment after only a few months of limited testing.

Tailless aircraft

A tailless aircraft has no tail assembly and no other horizontal surface besides its main wing. The aerodynamic control and stabilisation functions in both pitch and roll are incorporated into the main wing. A tailless type may still have a conventional vertical fin and rudder.

Poland Republic in Central Europe

Poland, officially the Republic of Poland, is a country located in Central Europe. It is divided into 16 administrative subdivisions, covering an area of 312,696 square kilometres (120,733 sq mi), and has a largely temperate seasonal climate. With a population of approximately 38.5 million people, Poland is the sixth most populous member state of the European Union. Poland's capital and largest metropolis is Warsaw. Other major cities include Kraków, Łódź, Wrocław, Poznań, Gdańsk, and Szczecin.

Contents

Design and development

Jarosław Naleszkiewicz's Naleszkiewicz JN 1, nicknamed Żabuś II (Froggy II; the Jach Żabuś was an earlier, unrelated Polish glider) was an experimental tailless glider which was intended to test the behaviour of a proposed twin-engined aircraft of the same configuration. It was preceded by a series of rubber-powered models which proved flight stability and suggested good performance. [1]

The Jach Żabuś {Jach Froggy) was a Polish glider designed to compete in the 1923 First Polish Glider Contest. It lacked vertical flying surfaces, had an unusual control system and made only one short flight. Rebuilt with conventional tail and controls, it won the distance flown prize at the second contest, held in 1925.

In essence the wooden JN 1 was a high aspect ratio, cantilever wing with a short, bulbous central nacelle and wingtip vertical surfaces. Its two part wing was trapezoidal in plan, with most of the sweep on the leading edge. Each part was built around a single spar with plywood covering ahead of it, forming a torsion resistant D-box, and fabric covering behind. Control surfaces filled the whole trailing edge, with elevators inboard and ailerons outboard. [1] [2]

Cantilever beam anchored at only one end

A cantilever is a rigid structural element, such as a beam or a plate, anchored at one end to a support from which it protrudes; this connection could also be perpendicular to a flat, vertical surface such as a wall. Cantilevers can also be constructed with trusses or slabs. When subjected to a structural load, the cantilever carries the load to the support where it is forced against by a moment and shear stress.

Leading edge

The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one. As an example of the distinction, during a tailslide, from an aerodynamic point of view, the trailing edge becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged.

Spar (aeronautics) Main structural member of the wing of an aircraft

In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries flight loads and the weight of the wings while on the ground. Other structural and forming members such as ribs may be attached to the spar or spars, with stressed skin construction also sharing the loads where it is used. There may be more than one spar in a wing or none at all. However, where a single spar carries the majority of the forces on it, it is known as the main spar.

The cockpit was within a ply-covered nacelle which reached forward from the trailing edge to well ahead of the leading edge. Its glazing provided good sideways, but limited forward, vision. A pneumatically-sprung skid under the nacelle provided the JN 2's landing gear. [1]

Landing gear aircraft part which supports the aircraft while not in the air

Landing gear is the undercarriage of an aircraft or spacecraft and may be used for either takeoff or landing. For aircraft it is generally both. It was also formerly called alighting gear by some manufacturers, such as the Glenn L. Martin Company.

At the wingtips endplate fins carried balanced rudders. Together these vertical surfaces had an elliptical profile, cropped and reinforced below the wing to protect it on the ground. The rudders could be used conventionally in unison or in opposition as airbrakes. [1] [2]

Fin flight control surface

A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.

Balanced rudder

Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevators and ailerons; all three aircraft control surfaces may also be mass balanced, chiefly to avoid aerodynamic flutter.

Operational history

The JN 1 first flew on 23 July, catapult-launched and flown by Francizek Jach in Gummistart. It proved to be hard to control, being oversensitive in pitch both via elevator control and centre of gravity position. Car-towed flights follows but the control difficulties persisted and in the autumn the JN 1 was damaged in a crash. It was not repaired because of a mixture of funding problems, a lack of official interest and Naleszkiewicz's absence due to a new job in Warsaw. [1] [2]

Warsaw Capital of Poland

Warsaw is the capital and largest city of Poland. The metropolis stands on the Vistula River in east-central Poland and its population is officially estimated at 1.78 million residents within a greater metropolitan area of 3.1 million residents, which makes Warsaw the 8th most-populous capital city in the European Union. The city limits cover 516.9 square kilometres (199.6 sq mi), while the metropolitan area covers 6,100.43 square kilometres (2,355.39 sq mi). Warsaw is an alpha global city, a major international tourist destination, and a significant cultural, political and economic hub. Its historical Old Town was designated a UNESCO World Heritage Site.

With its differentially operating rudders it may have the first glider fitted with air-brakes, [2] though of a very different type to the spoilers used a few years later on German sailplanes. [3]

Specifications

JN 1 KN Naleszkiewicz Zabus2 1932.jpg
JN 1
The JN 1 glider, the constructor stands next to the glider JN-1 4.jpg
The JN 1 glider, the constructor stands next to the glider

Data from Naleszkiewicz JN-1 Żabuś II, j2mcl-planeurs [2]

General characteristics

Performance

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References

  1. 1 2 3 4 5 Cynk, Jerzy (1971). Polish Aircraft 1893-1939 . London: Putnam Publishing. p. 732-3. ISBN   0 370 00085 4.
  2. 1 2 3 4 5 "Naleszkiewicz JN-1 Żabuś II". j2mcl-planeurs.net. Retrieved 11 January 2019.
  3. ↑ Simons, Martin (2006). Sailplanes 1920-1945 (2nd revised ed.). Königswinter: EQIP Werbung & Verlag GmbH. p. 25. ISBN   3 9806773 4 6.
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