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The Arado Ar 80 was a pre- World War II
fighter aircraft Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...
, designed by
Arado Flugzeugwerke Arado Flugzeugwerke was a German aircraft manufacturer, originally established as the Warnemünde factory of the Flugzeugbau Friedrichshafen firm, that produced land-based military aircraft and seaplanes during the First and Second World Wars. H ...
to compete for the ''
Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German '' Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegera ...
''s first major fighter contract. The Ar 80 was uninspiring in terms of performance and also suffered a number of failures. The contest was eventually won by the
Messerschmitt Bf 109 The Messerschmitt Bf 109 is a German World War II fighter aircraft that was, along with the Focke-Wulf Fw 190, the backbone of the Luftwaffe's fighter force. The Bf 109 first saw operational service in 1937 during the Spanish Civil War a ...
, and the Ar 80
prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and software programming. A prototype is generally used to ...
s ended their days as test aircraft.


Design and development

With the
Nazi Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in Naz ...
rise to power in February 1933, a plan was put into place to dramatically expand the ''Luftwaffe''. The new and highly-political ''
Reichsluftfahrtministerium The Ministry of Aviation (german: Reichsluftfahrtministerium, abbreviated RLM) was a government department during the period of Nazi Germany (1933–45). It is also the original name of the Detlev-Rohwedder-Haus building on the Wilhelmstrasse ...
'' (RLM) demanded that the large industrial firms cooperate, keeping construction as secret as possible. Arado Flugzeugwerke, under the direction of Erich Serno and Felix Wagenführ, largely stopped being a designer of aircraft and increasingly became a production facility for other companies. However, the company had just completed the Ar 65
biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While a ...
fighter. Several orders were placed for the Ar 65, and a follow-on Ar 68 model. This made Arado one of the few companies with actual fighter design experience, and they were considered for future developments In 1933, the ''Technisches Amt'', the technical department of the RLM, concluded a series of research projects into the future of air combat. One of these was ''Rüstungsflugzeug IV'' for an all-metal
monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...
single-seat
fighter aircraft Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...
, replacing the Ar 64 and
Heinkel He 51 The Heinkel He 51 was a German single-seat biplane which was produced in a number of different versions. It was initially developed as a fighter; a seaplane variant and a ground-attack version were also developed. It was a development of t ...
biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While a ...
s then in service. The plane needed to have a top speed of 400 km/h (250 mph) at 6,000 m (19,590 ft) which it could maintain for 20 minutes, while staying in the air for a total of 90 minutes. It was to be powered by the new
Junkers Jumo 210 The Jumo 210 was Junkers Motoren's first production inverted V12 gasoline aircraft engine, first produced in the early 1930s. Depending on the version it produced between 610 and 730 PS and can be considered a counterpart of the Rolls-Royce Kes ...
engine. It also needed to be armed with at least three
machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles ...
s with 1,000 rounds each, or one 20 mm
cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during ...
with 200 rounds. The plane needed to keep
wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...
below 100 kg/m2, which is a way of defining its ability to turn and climb. The priorities for the plane were level speed,
rate of climb In aeronautics, the rate of climb (RoC) is an aircraft's vertical speed, that is the positive or negative rate of altitude change with respect to time. In most ICAO member countries, even in otherwise metric countries, this is usually expressed ...
, and maneuverability, in that order.
Hermann Göring Hermann Wilhelm Göring (or Goering; ; 12 January 1893 – 15 October 1946) was a German politician, military leader and convicted war criminal. He was one of the most powerful figures in the Nazi Party, which ruled Germany from 1933 to 1 ...
sent out a letter in October 1933 asking for a "high speed courier aircraft" in order to start the work, and in May 1934, the actual R-IV request was sent out and made official. In addition to Heinkel and Arado,
Focke-Wulf Focke-Wulf Flugzeugbau AG () was a German manufacturer of civil and military aircraft before and during World War II. Many of the company's successful fighter aircraft designs were slight modifications of the Focke-Wulf Fw 190. It is one of the ...
, and Bayerische Flugzeugwerke competed. They had to deliver three prototypes for head-to-head testing in late 1934. Although Blume was officially the director of design at Arado, it was Rethel who did most of the early work on the design. Rethel was well aware of the advantages and disadvantages of the
monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...
technique, but the company had never built such a design and was thus at a distinct disadvantage in relation to Heinkel who had used it on their He 70 ''Blitz'' design from 1932. However he felt that he could not only design a successful monocoque aircraft, but in fact make one that was both lighter and easier to build than the techniques being used at other companies. His solution was to use two sets of skinning plates formed in long strips running front to back along the plane. The first set of plates was formed roughly into the shape of a C, which a small flange at the open ends of the C where they could be easily riveted to the hoop bulkheads. Using this system he was able to eliminate one more piece of internal structure, the stringers that would normally run between the bulkheads. He used a second set of sheets that were flat, so they could easily bend front-to-back. They were cut into teardrop shapes, which exactly fit into the gaps between the main
stringer Stringer may refer to: Structural elements * Stringer (aircraft), or longeron, a strip of wood or metal to which the skin of an aircraft is fastened * Stringer (slag), an inclusion, possibly leading to a defect, in cast metal * Stringer (stairs), ...
s. Not only did this system allow for the "perfect" aerodynamic shape, but in theory it was also lighter and easier to build. The system looked so hopeful that other parts of the aircraft's design were allowed to be heavier and less risky as the weight savings in the
fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft ...
should compensate. The rest of the plane was conventional. The forward fuselage and inner wings were formed up from steel tubing with removable
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
sheeting over it, the outer wings were aluminium formers and skinned with aluminium on top and fabric on the bottom. Like the Heinkel designs, the wing included a reverse-gull bend to shorten the
landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...
legs, but unlike the Heinkel it was almost straight on the
leading In typography, leading ( ) is the space between adjacent lines of type; the exact definition varies. In hand typesetting, leading is the thin strips of lead (or aluminium) that were inserted between lines of type in the composing stick to incre ...
and
trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...
s instead of the more complex elliptical planform favoured by the Günter brothers. In order to avoid cutting the outer wing formers with outward retracting gear, Rether decided to have the landing gear retract directly to the rear. To lie flat, the wheel would have to be rotated through 90° as it retracted, with its mainwheel resting atop the lower end of the strut as with the contemporary American
Curtiss P-36 Hawk The Curtiss P-36 Hawk, also known as the Curtiss Hawk Model 75, is an American-designed and built fighter aircraft of the 1930s and 40s. A contemporary of the Hawker Hurricane and Messerschmitt Bf 109, it was one of the first of a new generation ...
fighter design. To do this, Rethel placed the main oleo strut inside a larger tube that was mounted to the pivot point on the lower leading edge of the box-
spar SPAR, originally DESPAR, styled as DE SPAR, is a Dutch multinational that provides branding, supplies and support services for independently owned and operated food retail stores. It was founded in the Netherlands in 1932, by Adriaan van Well, ...
. As the gear retracted a small arm would pull on a lever mounted to the oleo, turning the leg inside the larger tube.


Prototypes and testing

The design, now known as the Ar 80, was completed without the aid of Rethel; he left the company in 1934 to join BFW leaving Blume in charge of the project. The plane was designed to mount the Jumo 210 engine, driving a wooden two-blade fixed-pitch propeller. However, this engine was not going to be ready until the contest was supposed to be over, so all of the contestants looked for other engines to fill the hole. In this case Arado proved to have the advantage, as they had already purchased a 391 kW (525 hp)
Rolls-Royce Kestrel The Kestrel or type F is a 21 litre (1,300 in³) 700 horsepower (520 kW) class V-12 aircraft engine from Rolls-Royce, their first cast-block engine and the pattern for most of their future piston-engine designs. Used during the interwar pe ...
VI engine for use on their Ar 67 design. The engine had less than optimal
supercharging In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. The current categorisation is that a supercharger is a form of forced induct ...
which led to poor performance for the Ar 67. The V1 prototype first took to the air in the spring of 1935, one of the first of the planes in the contest to do so. However, one of the company test pilots lost control at low altitude only weeks later, and V1 was written off. The landing gear had already proven to be a real problem in these few short weeks. It continued to stick half-closed when retracted, although luckily it returned to the down position for landing. Repeated attempts to find the problem were fruitless, when they put the plane on blocks in the
hangar A hangar is a building or structure designed to hold aircraft or spacecraft. Hangars are built of metal, wood, or concrete. The word ''hangar'' comes from Middle French ''hanghart'' ("enclosure near a house"), of Germanic origin, from Frankish ...
it would always work flawlessly. Eventually, it was found that the air pressure on the front of the strut in flight made the oleo jam in its tube so it couldn't rotate. Another problem discovered during construction of the V1 was that Rethel's monocoque technique in fact turned out to be much heavier than expected. Some of this was a problem in the actual design; since the sheets ran the length of the plane, they had to be as thick as the thickest point on the entire plane. More traditional designs could use lighter or heavier gauges in various places. The main problem, however, was that the design required considerably more rivets than expected, and as a result the plane was overweight. V2 was rushed to completion but the Jumo was still unavailable. In order to give the contestants some sort of realistic engine, the RLM had traded Rolls-Royce an He 70 for four 518 kW (695 hp) Kestrel V engines. Although the V was the same basic engine as the VI, it had much better supercharging and was in fact the most powerful inline engine of the day. The various companies competed heavily for access to these engines for their prototypes. Perhaps some idea of the future outcome can be seen in the fact that BFW received two, Arado and Heinkel one each, and Focke-Wulf none at all. V2 was completed with the Kestrel by autumn of 1937, and started company testing. Once again, the gear proved to be a problem. Blume immediately blamed all of the problems on Rethel, after noting that he was always skeptical of the design. He decided that the performance problems of having fixed gear would be offset by its lighter weight, and the Ar 80 then reverted to using a well- spatted and faired set of gear similar to those used on their various biplane designs. Several months were lost in the conversion. The use of the fixed gear didn't save as much weight as expected and the plane was still 16% over the design weight at 1,630 kg (3,590 lb) empty. Fully loaded the plane was 2,100 kg (4,630 lb) even without armament, which made it underpowered even with the Kestrel V. Drag was also higher than expected. Thus, the plane proved to have very disappointing performance, reaching only 410 km/h (255 mph). In early 1936, the Jumo engines finally arrived. The 210 had even less takeoff power than the Kestrel, but its altitude performance was comparable. Speed did increase with this engine at higher altitudes, but low-level speed and climb performance both dropped. Arado argued that the fitting of a
constant speed propeller In aeronautics, a variable-pitch propeller is a type of propeller (airscrew) with blades that can be rotated around their long axis to change the blade pitch. A controllable-pitch propeller is one where the pitch is controlled manually by the p ...
would boost both, with the speed climbing to 425 km/h (264 mph), but this was not attempted before the plane was sent off to the contest. Although the Ar 80 had been one of the first planes to fly, the continued problems with the gear and engine supply meant it was one of the last to arrive for the head-to-head fly-off. It was delivered to Travemünde on 8 February 1936, and later moved to meet the rest of the planes at Rechlin-Lärz Airfield in March. It was clear all along that the plane had no chance against the Heinkel and BFW designs, a fact that Arado was made officially aware of after only one month. By this point, V3 was already finished. In order to try to save weight, the design had removed the gull-wing and replaced it with a "flat" one, requiring slightly longer gear legs. It also mounted the Jumo 210C with the constant-speed propeller, which boosted speed to 410 km/h (255 mph). By this time, the RLM had already given up on the design, so the plane was not sent for testing and instead hangared at the Arado plant. In 1937, the V3 was resurrected as a flying testbed for several experiments. It was fitted with a second seat behind the pilot for an observer, and also added an enclosed
canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...
. The plane was first used for testing a 20 mm cannon firing through the spinner, making it the first German cannon-armed fighter. This system, called the "''motorkanone''" - an armament format pioneered with the 37 mm cannon-armed French
SPAD S.XII The SPAD S.XII or SPAD 12 was a French single-seat biplane fighter aircraft of the First World War developed from the successful SPAD VII by Louis Béchereau, chief designer of the Société Pour L'Aviation et ses Dérivés (SPAD). Development ...
in World War I - would become a standard feature of most German inline engined fighter designs during the war. In 1938, the V3 was rebuilt once again, this time to test a new
Fowler Flap A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing ...
design Arado was intending to use on their Ar 198 and Ar 240. Testing showed that the flap was so effective that the lift distribution along the wing changed radically, so a further modification was added to "droop" the
aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement aroun ...
s along with the flaps. Testing continued for some time in this form, resulting in the "Arado traveling aileron" and "Arado landing flap".


Specifications (Ar 80 V2 (Jumo engine))


See also


References

*Armin Kranzhoff, Jörg (1997).''Arado:History of an Aircraft Company'', Schiffer Publishing. * *Green, William (1990).''Warplanes of the Third Reich'', William Green, Galahad Books. *


External links


Luftwaffe Resource Centre
{{RLM aircraft designations Low-wing aircraft Single-engined tractor aircraft Arado Ar 080 Ar 080