Armstrong Whitworth Siskin Mk.III/Mk.IIIA - British Users

In  1922 the 14/22 specification was issued by the Air Ministry for an all-metal single-seat high performance airplane and one Armstrong Siddeley Jaguar powered prototype was ordered from Armstrong Whitworth.

Apart from re-engining the airplane, in order to fit the Jaguar IV engine, Major Green, the original designer of the Siskin, redesigned it with an all-metal fuselage, as the Siskin III.
It was praised by the Air Ministry, which placed a contract for three production aircraft on 13th October 1922, with a further six ordered on  26th January 1923, being one of them a prototype for a two-seat variant.
The Siskin Mk.III flew for the first time on 7th May 1923 and the first deliveries to the RAF took place in January 1924. It was the first all-metal fighter to serve with the Royal Air Force.

The Siskin Mk.III was powered by a 385hp Armstrong Siddeley Jaguar IV radial engine and was armed with two Vickers 0.303 machine-guns placed at the sides of the frontern part of the fuselage.

The main production variant, the Siskin Mk.IIIA, was ordered in 1926 and, initially it was powered by a regular Jaguar IV engine, but it was re-engined with the supercharged version of that same engine, the Jaguar IVA. The supercharged engine concept was a novel idea for the time and had little impact on the performance below the 3050m, but it improved the performance and climb rate above that height.
It was powered by a single Armstrong Siddeley Jaguar IVA engine, delivering also 385hp of power, was armed with two Vickers 0.303 machine guns, this time buried in the frontal part of the fuselage, instead of the sides, like the regular Mk.III had and it could carry up to four 9Kg small bombs under the wings.
As Armstrong Whitworth was busy manufacturing the Armstrong Whitworth Atlas, many of the later production of the Siskin was contracted to other firms like Blackburn, Bristol, Gloster and Vickers.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Siskin
2. Salamander Books - The Complete Book of Fighters

Armstrong Whitworth Siskin Mk.IIIA - Foreign Users

The Armstrong Whitworth Siskin was a British single-seat biplane fighter of the 1920s that was used by some foreign users, Canada and Estonia, more precisely.

The Royal Canadian Air Force used the Sisikin from 1926 until 1939. They were sent in 1926 to be tested under winter flying conditions, equipped with skis instead of regular wheels and the original modified type was piloted by Clenell H. Dickins. It was considered as a very advanced airplanes fighter for the time and the RCAF eventually bought them and they were assigned to the Flight No.1 based at Camp Borden and Trenton, in Ontario.
In 1937 the Flight was reformed and it became the No.1 Squadron Royal Canadian Air Force and was moved from Trenton and Borden to Calgary, in Alberta.

It remained active with that unit until 1939 when, due to the outbreak of the war, it was replaced by the more modern Hawker Hurricane.
It also equipped the first RCAF flight demonstration unit, the Siskin Air Demonstration team, nicknamed 'The Siskins'.

Apparently, Estonia also purchased some Siskins, not the fighter ones, but the trainer one, the Siskin IIIDC, which was a two-seater. However further details about those airplanes under Estonian command are unknown.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Siskin
2. http://www.canadianwings.com/Aircraft/aircraftDetail.php?SISKIN-6
3. Salamander Books - The Complete Book of Fighters.

Armstrong Whitworth Siskin - Prototype and Mk.II

The Armstrong Whitworth Siskin was a British single-seat bipane fighter of the 1920s and was one of the first airplanes to enter service with the Royal Air Force after the end of the World War I.

The first prototype, was built by Siddeley-Deasy, company that was soon incorporated into Armstrong Whitworth, and was designed by Major F.M. Green who was the former chief engineer of the Royal Aircraft Factory. Initally it was Siddeley-Deasy's candidate for the Type1 fighter for a single-seat fighter powered by the ABC Dragonfly radial engine.
The S.R.2 Siskin was a single-bay biplane made out of wood and fabric. Wings were of unequal span and it was fitted with a distinctive fixed landing gear equipped with long oleo strut shock absorbers carrying the axle which was connected to the Radius Rods by a pair of V-struts. The engine was fitted inside a streamlined cowling to reduce drag with each cylinder coming out through special holes designed for them. It was armed with a pair of 0,303 Vickers machine-guns placed at the sides of the frontern part of the airplane.

It flew first in May 1919 and the Dragonfly engine delivered 270hp of power, instead of the theorical 320hp and, in spite of all the expectations put on the Dragonfly engine, it proved to be a disaster as it was underpowered and it was very unreliable being very prone to overheating and causing an untolerable amount of vibration. Even if those were serious issues, the Siskin proved to handle better than it's Dragonfly powered competitors.

The second version, the Mk.II, derived directly from the Siddeley-Deasy S.R.2 which was adquired by Armstrong Whitworth after Siddeley-Deasy closed down their aviation department. It reatined the basic features of it's predecessor but, on the other hand, it was radically redesigned structurally. It embodied fuselage and wing spars of high-tensile steel tubing and strip. The engine was switched from the ABC Dragonfly to the newly built Armstrong-Siddeley Jaguar 14-cylinder two-row that could deliver 325hp of power. It was armed, as the Siddeley-Deasy Siskin, with a pair of 0,303 Vickers machine-guns.
It appeared in August 1922 and the second one was completed in October 1923 but it failed to attract production order so it was sold to the Swedish Aircraft Company of the Signal Corps (the forerunner of the Swedish air force) where it was fitted with skis to make it able to land under winter conditions.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Siskin
2. Salamander Books - The Complete Book of FIghters

Airspeed AS.56

After the Air Ministry issued the specification F.6/42 to replace  the Hawker Typhoon, which was an excellent fighter bomber but was considered too big for a single-seat fighter. Many companies showed interest, among them Boulton Paul, Hawker (which won the contest with the Hawker Tempest), Vickers, Supermarine, Westland and Airspeed.

It was going to be powered by a Napier Sabre IV, as it was a requirement of the Ministry's specification. The engine was going to be equipped with a fan-cooled annular radiator in order to reduce drag. It was going to have four 20mm cannons in the wings and, most probably, bomb capacity under the wings.
Anyway, the design on the work was abandoned, however the arrangement of the radiator was continued by the Napier in order to solve the Sabre's overheating problems and it was tested both in Hawker Typhoon and Hawker Tempest.

Sources:
1. Midland Publishing - British Secret Projects - Fighters and Bombers 1935-1945
2. Putnam's Books - Airspeed Aircraft since 1931

Armstrong Whitworth Ara

The Armstron Whitworth Ara was a British biplane Fighter designed in the closing stages of the World War I.

In early 1918 the British Air Ministry issued an specification for a fighter capable of replacing the Sopwith Snipe and it had to be powered by the 320hp ABC Dragonfly radial engine which was very promising before even any field testing was carried out. In order to meet this specification, Fred Murphy, the head designer of Armstrong Whitworth designed this fighter, with three prototypes being ordered.

It was a two-bay biplane with an square fuselage and the engine covered in a pointed cowling but with the cylinder heads exposed. Upper wing was placed low on purpose in order to give the pilot a better upwards field of view.

Just like the other candidates to replace the Snipe, the Dragonfly engine prooved to be very disappointing when the first prototype was tested in early 1919. However a second prototype was completed and flown before late 1919. It was abandoned towards the end of the year and Armstrong Whitworth's aircraft department closed down.

It was going to be armed with a pair of Vickers 0.303 (7.7mm) Machine guns.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Ara
2. Salamander Books - The Complete Book of Fighters

Airspeed AS.47/48/49

We are covering three unbuilt British airplanes in this post, even if two of them are left undrawn because there aren't blueprints of them, or at least we couldn't find them.

The Airspeed AS.47 was designed in 1939 and was going to be a twin-boom bomber project with two engines in the tractor-pusher configuration, with each engine having a four-bladed propeller. The fuselage was cylindrical with the cockpit placed a little bit to the left of the axis of the fuselage. It was expected that it could carry an internal bomb load of 454kg. plus some unespecified amount under the wings.
It was going to be powered by two Napier Sabre and were expected to deliver 2200hp of power, each of them. Apparently, the rear engine could be detached in order to create an emergency exit.
Considering also that the speed of this airplane was expected to be high, it was believed that it wasn't going to need any defensive armament.

The Airspeed AS.48 and AS.49 were also designed in 1939. The AS.48 was going to be a single-seat night fighter project and the AS.49 was going to be the trainer version of the AS.48. As we could only find text referenced to those projects and not any blueprint or drawing whatsoever, they aren't drawn.

Sources:
1. http://raigap.livejournal.com/401554.html (translated)
2. Putnam's British Aircraft - Airspeed Aircraft Since 1931

Armstrong Whitworth Armadillo

The Armstrong Whitworth Armadillo was a British single-seat fighter prototype built by Armstrong Whitworth during the last months of the World War I.

It was designed in 1917 by Fred Murphy, who was the new chief designer at Armstrong Whitworth as a private venture powered by a 230hp Bentley BR2 rotary engine. Even if the design met the requierements of the Air Board Specification A1(a) for a replacement for the Sopwith Camel, it was built to test the skills of the Armstrong Whitworth new design team, and wasn't considered as a serious contender for the requirement. However, Armstrong Whitworth was granted a license to build to prototypes.

It was a two-bay biplane with a square section fuselage. The engine, located in the nose, a rotary 230hp Bentley BR2 was enclosed by a circular cowl with a deep hump above the cowl where the armament, a pair of 0.303 Vickers machine guns, was fitted.

It flew for the first time in April 1918 and it wasn't accepted into formal evaluation by the Air Ministry, which criticised the poor view from the cockpit. Anyway, when the Armadillo was already being evaluated, the Sopwith Snipe, which was powered by the same engine and was faster was already in large scale production and had been combat tested, so Murphy abandoned the Armadillo and instead concentrated on the more advanced Ara.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_Armadillo
2. Salamander Books - The Complete Book of Fighters

Airspeed AS.31

So, today we're posting one of the most bizarre, if not the most bizarre one, airplane designs you're going to see for a long long time, the Airspeed AS.31.

Designed for the specification 35/35, the Airspeed AS.31 was an experimental high-speed airplane that could carry eight wing-mounted guns, just like the Hawker Hurricane or the Supermarine Spitfire did.
Four airplane developing firms entered in the contest to win the contract, and this was, by far, the most unusual design to be submitted.
It was a tractor monoplane where the tailplane, fixed to the wing by twin metal booms, housed the egg-shaped cockpit. No rudder or fin surface was indicated in the blueprints whatsoever. However some split flaps were fitted across the trailing edge of the wing, between the booms, with the wide-span ailerons outboarding them. A widetrack undercarriage arrangement was to be fitted and the airplane was to be powered by a Rolls-Royce Merlin E engine.

Apparently a wing tunnel scale model was made, which, after tested, it showed that this unusual arrangement generated an intolerable amount of G-forces during high speed turns and the design was completely abandoned.

Sources:
1. http://www.secretprojects.co.uk/forum/index.php?topic=2407.msg20160#msg20160
2. http://www.fantastic-plastic.com/AIRSPEED%20AS31%20PAGE.htm
3. Putnam's British Aircraft - Airspeed Aircraft since 1931

Royal Aircraft Factory S.E.5 - Foreign Users part two

Note: Just another post to cope with the new nation tags. Nothing new.

• South Africa: The SE.5a was the backbone of the newly created South African Air Force in 1921. It may have taken part in the suppression of the Second Rand Rebellion in 1921.
• Soviet Union: Apparently the Bolshevik forces captured the Polish airplane and it was used in the Russian Civil war.
• Spain: The Spanish government bought at least one (some sources claim that they were two) SE.5a from the surplus of the Great War.
• USA: The SE.5a served with the USAAS (United States Army Air Service) and was locally produced by the Austin aviation company who manufactured 1650 exemplars of it. Curtiss also manufactured one of it out of 1000 planned. Eberhart company also manufactured it's own trainer version out of spare parts and they served as advanced trainers well into the late 20s.

Hansa-Brandenburg W.29 - Foreign Users Part Two

Note: This post is just a re-arrangement of the original one, the Hansa-Brandenburg W.29, in order to cope with the new national -and historical tags - As the drawings aren't new, we haven't announced it through twitter.

The countries covered here are:

Japan: The imperial Japanese Navy used them. They were locally produced by Aichi and Nakajima and featured a locally produced engine. They were named Type Hansa Surveillance Floatplane.

Netherlands: Apparently one ex-German floatplane serving in the Seeluftstation Flandern had to make an emergency landing in the neutral Holland. The Dutch captured the airplane and commissioned it into service with their navy.

Norway: The Royal Norwegian air force received two W.29 and used them to support the coastal artillery units. It was designated as Måke I  and they served in that role until 1928 when they were transfered to the Royal Norwegian Navy. 

Note: Apparently there's a lot of confusion about the Norwegian W.29. It seems that the W.29 were named Måke I, and, contrary to what wikipedia claims, it wasn't produced by the Kjeller factory. The Måke II and Måke III were produced by that factory but they were based on the W.33 not on the W.29.

Sopwith Pup - Foreign Users

Note: This post is just a re-arrangement of our first one, the Sopwith Pup in order to cope with the new national -and historical tags - As the drawings aren't new, we haven't announced it through twitter.

The users contained in this post are:

• Australia: The Sopwith Pup equipped the Australian No.5, No.6 and No.8 Training Squadrons and they also equipped the No.1 Flying training School RAAF in the post-war years.
• Belgium: It seems that the Belgian 5éme Escadrille de Chasse employed at least one Sopwith Pup during the World War I.
• Greece: During the First World War some Pups were used by the Hellenic Army Air Service.
• Netherlands: Apparently Netherlands used some airplanes that had crashed inside their borders during the First World War.
• Japan: The Imperial Japanese Air Force used the Pup, both with the army and the navy, where it's known that some of them served aboard the Yamashiro Battleship.
• Romania: Apparently some Pups served with Romania during the First World War.
• Russian Empire: It seems that some Pups were sold to the Imperial Russian air corps.
• Russian SFSR: When the revolution started, with the subsequent civil war, the Bolsheviks employed some captured ex-white Pups.
• USA: It's claimed that the US Navy used some Pups.

Armstrong Whitworth F.K.9/F.K.10

The Armstrong Whitworth F.K.9 and F.K.10 were British two-seat quadruplanes (four winged) fighter airplanes that were built by Armstrong-Whitworth. It was ordered by both the Royal Flying Corps and Royal Naval Air Service but it wasn't used operationally even if it was one of the few quadruplanes to materialize.

It was designed in 1916 by Frederick Koolhoven who was the chief engineer at Armstrong Whitworth as a single-engine two-seat fighter. He opted for the quadruplane configuration that was also chosen for other anti-zeppelin fighter like the Pemberton-Billing P.B.29E, Supermarine Nighthawk and the Wright Quadruplane, all of that when Sopwith were designing and building their successful Sopwith Triplane fighter.

The first prototype, named Armstrong Whitworth F.K.9 was built and flown for the first time in the summer of 1916 and was powered bya a 110hp Clerget 9Z engine. It had a shallow fuselage with the wings joined by a plank-like interplane struts. It was unarmed and, after being evaluated at the Central Flying School in late 1916 an order of 50 for the improved version, the F.K.10 even if it wasn't produced yet.
The F.K.10 featured a new and deeper fuselage, a new tail and held the wing configuration of the F.K.9. It was armed with a forward firign synchronised 0.303 Vickers machine gun and with another one mounted in the observer cockpit. It was powered by either a 130hp Clerget 9B or LeRhône 9J engine. However it showed inferior performance than the Sopwith Strutter, which was already in service at the frontlines performing the two-seat fighter role, even if it wasn't it's initial one. That's why only five of them were built for the RFC and three more for the RNAS and they weren't employed operationally and it wasn't developed further.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_F.K.10
2. Salamander Books - The Complete Book of Fighters

Airspeed AS.9

Today we post about an unbuilt fighter project that would have been kinda revolutionary for it's time.

The Airspeed AS.9 was a strut-braced interceptor low-wing fighter with an unusual feature for it's time, 1935: retractable landing gear, flaps and controllable pitch propeller.

It was going to be powered by either a 650hp Napier Dagger II 24-cylinder air-cooled H-type (as shown in our drawings) or with a Rolls-Royce Kestrel delivering 700hp of power. It was thought as a low-cost but, nonetheless advanced fighter.
Fuselage was going to be of welded steel-tube with fabric-covered wings. It was going to be armed with two machine guns located at the nose, firing through the propeller, and there were also plans to fit more machine-guns in the wings (probably of higher caliber).

Sources:
1.- http://forum.worldofwarplanes.com/index.php?/topic/31516-spoiler-what-the-british-tech-tree-could-look-like/
2.- Putnam's British Aircraft - Airspeed Aircraft Since 1931

Armstrong Whitworth F.K.6

The Armstrong Whitworth F.K.5 and F.K.6 were experimental intended to serve as escort fighters built by Armstrong Whitworth during the First World War.

Early in 1916 the British war office drew up an specification for a multi-seat escort fighter to be powered by the new Rolls-Royce Eagle engine. It had to have at least 7 endurance hours and it had to protect the bomber formations from German fighters such as the Fokker E.I and it had to be capable also of destroying enemy airships. The orders for prototypes were placed from Armstrong Whitworth, Sopwith and Vickers, and all of them presented unorthodox designs given the need to give the gunners a good field of fire, specially considering the lack of syncronisation gear.

Frederick Koolhoven originally designed the F.K.5 as a tractor triplane with the middle wing having much greater span than the upper and lower ones. Gunners were mounted in nacelles placed on top of the middle wing making them to sit ahead of the propeller blade and the pilot cockpit placed behind the wings having that way a poor view. Undercarriage consisted in a sprung stut with two main wheels under the engine with two stabilishing ones at the wingtips of the lower wings with a tail slid aft of the trailing edge of the lower wing. This design never flew because the head of Armstrong Whitworth aircraft department, had forbidden the test flights.

However, Koolhoven radically redesigned the F.K.5 in order to design the F.K.6. It still was a triplane with the middle wing having much greater span than the upper and lower ones. Gunner nacelles were slung under the middle wing and were significally shorter so the gunners sat behind and outboard the propeller. Fuselage was also deeper than the F.K.5 one, giving that way an slighlty better view from the cockpit and the undercarriage had two pair of wheels with a narrow track under the fuselage and a more conventional tail skid.
It was powered by a 250hp Rolls-Royce 12-cylinder water-cooled engine and would have carried two 0.303in Vickers machine guns, one in each nacelle.

Four airplanes were ordered in April 1916, two of which were to enter service with the Royal Naval Air Service, but only one was built as it demonstrated poor performance after flight tests. As effective synchronisation gears were already available by then, this type of airplane was abandoned and none of them were brought into production.

Sources:
1. https://en.wikipedia.org/wiki/Armstrong_Whitworth_F.K.6
2. Salamander Books - The Complete Book of Fighters.

Arado TEW 16/43-15

This design was proposed simultaneously with the other TEW ones, which were a rocket fighter (TEW 16/43-13), a pure jet fighter powered by two engines (TEW 16/43-23) and a mixed rocket/jet fighter one, (TEW 16/43-15).
As it happened with another Focke-Wulf design, the similarities with the Heinkel He.162 "Salamander" are evident.

This design would've been almost impossible to materialize given the hard problems that the intended powerplant would have given at the time.

This project, dating from 20th March 1943 was to be for an all-metal fuselage aircraft with a fuselage identical to that of the TEW 16/43-13, except that it was lengthened in order to fit an extra fuel tank and the extra engine. Most probably it would've been powered by the Heinkel HeS 011A delivering a thrust of 1300Kg mounted atop of the fuselage behind the cockpit. In order to improve the climb rate above the 10000m high a Walter HWK 509A bi-fuel rocket engine was fitted at the rear of the fuselage together with the T-Stoff and C-Stoff tanks, just like an afterburner. Wings were swept back at 25 degrees and were low on the fuselage.
Due to the particular placement of the engine, a twin fin and rudder configuration was chosen and, in order to save more space within the fuselage, a new type of landing gear was proposed. Main wheels were replaced with small ones placed in tandem, so the space needed when retracted was minimal. Those placed at the nose and the main ones retracted forwards.
The cockpit was going to be placed at the front and would've offered and excellent field of view, but, on the other hand, the rear vision would've been really poor due to the engine and air intake position.
It was going to be armed with a pair of 15mm MG151 or two 20mm MG151 cannons and one or two 30mm MK103 or MK 108 cannons, all of them located at the forward fuselage sides.

It's worth to mention that after the war, the Allies built many "combination fighters" albeit most of them in prototype form in order to perform the interceptor role, those are, among other, the American Republic XF-91 Thunderceptor, the French Dassault MD.550 Mirage I and SNCASE SE.212 Durandal and the British Saunders-Roe SR.53, amont others, even if all of them were abandoned during the development stage in favour of the fast climbing fighters having more powerful afterburners.

Sources:
1. http://www.luft46.com/arado/artew15.html
2. Midland Publishing - Luftwaffe Secret Projects - Fighters 1939-1945

Arado Ar. Projekt I

This airplane was a consequence of the studies for a tail-less airplane conducted for the eventual design of the E.555 bomber and the E.581 proposal.

This design and the E.555 they both share some characteristics like the wing mounted fin and rudder assemblies which also served as boundary layer fences.
Coping with the 27th January 1945 specification, the initial idea was to design a twin-jet night and all-weather fighter that had almost a complete delta wing shape. However, in March of that same year, the requirements changed and, in order to follow them, the design was modified to make it broader just to accommodate a third crew member and to have bigger fuel capacity. From that moment on, it featured a swept wing and was submitted to the EHK in Berlin.
However, on 20/21st March the specialist from the RLM criticised the large, drag-inducing surface area of the aircraft and the unfavourable placement of the engines. Inmediately after that report, another design was proposed featuring a smaller and sharper swept wing, however only written reports of this last one proposal have survived.

It was going to be powered by two Heinkel HeS 011A turbojet engines, delivering 1300Kn thrust each of them, weaponry would consist of two forward firing 30mm MK213 cannons, two oblique upward firing 30mm MK108 cannons placed near the centre of gravity of the airplane and another two rearward-firing 30mm MK213 cannons in a defensive guns arrangement. It could have also carried up to 500Kg of bombs.

It's obvious that this design influenced some airplanes, like the American Vought F7U Cutlass carrier based fighter, which was a more orthodoxal design heavily based on this design.

Sources:
1. http://www.luft46.com/arado/arpi.html
2. Midland Publishing - Luftwaffe Secret Projects - Fighters 1939-1945

Arado Ar E.580

This airplane must have beaten some kind of record because the RLM gave Arado only two days to complete this design. The requirements given by the Technische Amt in September 1944 were that it had to be a lightweight fighter powered by a single BMW 003 turbojet engine and the deadline was just a matter of days. Apparently the RLM specifications were very precise regarding the design lines and technical specifications.

Once designed it had certain similarities with the Heinkel He.162 even if it featured a low-mounted wing. Another risky characteristic was the position of the cockpit canopy inmediately ahead of the engine air intake which could made the even smallest airflow vortices to loose a considerable amount of performance, up to a 10% as a Rechlin test pilot told once. That was a problem that could have been easily fixed using a wind tunnel test model, however as the time was lacking when designing this airplane, there wasn't any time left to perform wind-tunnel testing. The fuselage was made out of steel and the wings, as specified in the RLM requirement, were made out of wood.

The tail had twin fins and rudders it was going to be powered by a single BMW 003A-1 delivering 800Kp of thrust and it was going to be armed with two 20mm MG 151/20 cannons or two 30mm MK108 cannons mounted in the nose. As it's evident, the RLM chose the He.162 Salamander design and this, the E.580 never went beyond the drawing board.

Sources:
1. http://www.luft46.com/arado/are580.html
2. Midland Publishing - Luftwaffe Secret Projects - Fighters 1939-1945

Arado TEW 16/43-23

Preliminary note: As it seems to be certain controversy about the lengthness of this airplane, some websites like luft46 or militaryfactory claim that this airplane was 12,2m long while the book we are using as a reference, gives an overall length of 9,40m long, significatively shorter. We believe that it's because of the resemblance this airplane has with the also never-built fighter version of the Arado Ar.234 which had a similar lengthness of 12,64m long.

During May 1943 Arado proposed to the RLM to make an extremely heavy fighter version of their Ar.234 but the expected performance didn't satisfy them because it barely had any improvement over the Messerschmitt Me.262 which was already being flight-tested. The designer Van Nes hoped that sweping the wing, reducing the overall dimensions and fitting more powerful engines, he could achieve performances that would offer a better rate of climb and enough endurance to counter the Allied bombers.

It was roughly comparable to the Me.262 in terms of dimensions and was intended to be able of reaching speeds of around the 1000km/h. However those expectations seem far fetched as a pure jet interceptor fighter, range and endurance numbers wouldn't have been particularly high and Arado didn't publish any data at all.
That's why Arado concentrated on two-seat fast general purpose or bomber airplanes. However, in the last months of the Third Reich, the company presented new proposals for jet-powered fighters, appart from their E.580 (presented for the Volksjäger specification) and the E.581 (presented as a successor of the Me.262), which consisted in the heavy fighter variants of the Ar.234 none of which went beyond the design board. Those proposals differed from the Ar.234B and C bomber and recon variants only in terms of military equipment and a new cockpit arrangement.

It was going to be powered by two Heinkel HeS 011 engines that could deliver 12,01Kn of maximum thrust each mounted below the wings. The fuselage hosted three fuel tanks located behind the cockpit and a single fin and rudder was fitted with the tailplanes having a small amount of sweep too. The landing gear would have rotated 90º before retracting inside the wing and a small spherical tire was going to be fitted in the nose. It was going to be armed with a single 15mm MG 151/15 machine gun and two 20mm MG 213/20 cannons all of them located in the nose beneath the cockpit.

Sources: 
1. http://www.luft46.com/arado/artew23.html
2. Midland Publishing - Luftwaffe Secret Projects - Fighters 1939-1945

Arado TEW 16/43-13

In the summer of 1943 the design department of Arado completed an extensive study about the development of jet fighters and the designer Wilhelm van Nes presented three designs a twin-jet one, a rocket powered one and a mixed rocket/jet one.

This desing was a conventional looking low swept-wing with slight dihedral fixed to the fuselage. The pilot seated in the frontern part of the fuselage which was caped in the nose with an aerodinamical cone.
It was designed to carry as much fuel as possible containing the famous T-Stoff and C-Stoff propellants. It was going to be powered by a single Walter HWK 509A which could deliver an adjustable thrust from 1Kn to 15.7Kn. positioned at the back of the fuselage. It had a single tail and an horizontal wings with swept surfaces. It was going to be armed with a pair of 20mm MG151 and another pair of 30mm MK108 cannons, all of them placed under the cockpit, in the fuselage nose. It was spaced in pairs to either side and below the cockpit.
Undercarriage was completely retractable in a tricycle arrangement with two main wheels located at the back and the auxiliar one at the nose. This particular arrangement was revolutionary for it's time because it helped saving a lot of space.

Sources:
1. http://www.luft46.com/arado/artew13.html
2. http://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=674

Arado Ar.E.561

A preliminar note about the lenghtness of this airplane: It seems that the length is controversial to say the least. Apparently the official length data claims that it was going to be 17,5m long, however, as the authors of the book Luftwaffe Secret Projects - Ground Assault & Special Purpose Aircraft point, that lengthness seems too be far fetched and they say that it was going to be no shorter than 10m long but no longer than 17,5m So, considering that the Bf.110 was 12,3m long and this airplane was going to be longer than the Bf.110, we opted for a middle-point lengthness and gave the airplane a lengthness of  14m long.

As the RLM issued a new requirement for a multi-seat heavy Zerstörer able of achieving speeds of 550/600km/h at an altittude of 6000m high in the end of 1936, Arado submitted this proposal in the early 1937.
It was going to feature a low cantilever wing, twin endplate fins and rudders and a crew of three. Just like the AGO Ao 225, it gave the feeling of being a conventional twin-engined aircraft except for the buried side-by-side 850hp DB 600 engines tilted at 44º to each other driving opposite-rotating wing-mounted propellers using remote drive shafts.
It also was going to have annular radiators in the wings nacelles, however, further studies showed that this engine arrangement was unsuitable for high-power engines because the components lacked strength causing that way many distortions and the manufacture of a drive of those characteristics was beyond the technological capabilities of those years. It was going to fit the Junkers shaft drive system but it was only suitable for low-end engines, not high-end ones, so Arado decided to withdraw the project and the RLM didn't show any further interest.

It was going to be armed with four cannons in the fuselage and nose, most probably 20mm MG FF ones, and two defensive machine guns, one at the rear of the cockpit, operated by the gunner/radio operator where most probably a pair of 7,92mm MG 15 were going to stand and another pair would have been located in the lower rear end of the fuselage where a defensive canopy would have been located having it's operator lying there in prone position.

Sources:
1. http://www.luft46.com/arado/are561.html
2. Midland Publishing - Luftwaffe Secret Projects - Ground Assault & Special Purpose Aircraft

Arado Ar. Projekt II

Preliminary note: At first, we thought that we got the length and/or the scale wrong because it seemed too long. After double-checking every measure we arrived to the conclusion that it wasn't wrongly sized or scaled. It was going to be that big.

Based on the Arado experience with the Ar.234 bomber and, in a lesser extent, based on their TEW 16/23-43 Arado designed this all-weather interceptor using a more orthodox design. It was expected to achieve significant reductions regarding both development risk and expenditure. Apparently some discarded designs show that a V-tailed variant was also planned.

In technical terms it was going to be powered by two Heinkel HeS 011A turbojets engines located in underwing nacelles each rated at 1300KpS thrust or two BMW 003A-1. It was going to be armed with two or four forward firing 30mm MK213 cannons in the nose, two oblique firing 30mm MK108 cannons (using the famous Schräge Musik system) and a rearward firing 30mm MK213 cannon as a defensive weapon and was expected that it could carry three 500Kg bombs.
Regarding avionics, it was going to be equipped with either one of the German radar systems like the FuG 24, FuG 29, FuG 25a, FuBI 3, FuG 101, Peil G6, APZ 6, FuG 244 or FuG 280.
The crew of two was inside a totally pressurized cabin which was going to feature ejector seats and the wings were going to be sweeped back at 35 degrees.

The design wasn't liked by the RLM which considered that this one was the least satisfactory of all the designs submitted. They criticized the large surface areas and unfavourable drag-inducing arrangement of the underwing engines.
Anyway, it's obvious how this design influenced on some post war airplane designers, like the Soviet Yakovlev Yak-25 for instance.
Edit: We have slightly modified the drawing in order to show the aircraft armed with the menacing Ruhrstahl X-4 air-to-air missile.

Sources:
1. http://www.luft46.com/arado/arpii.html
2. Midland Publishing - Luftwaffe Secret Projects - Fighters 1939-1945

Arado E.654 "Skorpion"

Designed by Arado's main designer, Walter Blume, the Arado E.654 Kampfzerstörer (destroyer, heavy fighter or fast bomber) was basically an enlengthned version of the Ar.240 in order to fit two propeller driven 2000hp Daimler Benz DB 614 or DB 627 mounted side by side and inclined in 15 degrees.

The engines drove the propellers using a complicated and controversial method which was designed back in 1941. Basically the right angle gear boxes and long drive shafts connected the propellers to the engines mounted in the fuselage. Theoretically this system was going to radically reduce the drag caused by the larger wing engine nacelles and kept the engines more protected within the fuselage.

The E.654 had a single vertical fin and rudder with the tailplane set at the top of the fin. That's where the nickname of this airplane comes from, because in some handwritten notes from Walter Blume himself, show that the streamlined body on top of the junction with the vertical tail, resembled the sting of an scorpion. Wings were straight and showed taper both on leading and trailing edges. A trycicle configuration based landing gear was chosen with the two frontal main wheel retracting into the engine nacelles and the smaller tail one retracting into the fuselage.

The crew of two, one pilot and a radio/radar operator who also acted as a gunner sat back to back inside the cockpit located at the frontal part of the fuselage. It was armed with six 30mm MK103 cannons mounted in two cheeks located at the bottom part of the nose and, the defensive armament consisted in two remote-controlled turrets containing each of them two 13mm MG131 machine guns. It had also a hardpoint under the main part of the fuselage in order to carry some bombs (or, as we imagined it, a torpedo, which it's just a work of our imagination as there were no references to a torpedo bomber version).

Junkers and Dornier had already experimented with the shaft drive systems and obtained satisfactory results when using short shafts. Anyway there were no practical experiencies available yet with the right angle gear boxes and long multisection drive shafts that had to be able of absorbing the engine power and passing it to the propellers while keeping the vibration under control. However, Walter Blume tried to find an engineering-based solution to those problems but, just like happened with another of his previous Zerstörer designs, the E.561, it was abandoned due to the lack of interest of the RLM in this kind of system.

Edit: We have redrawn the Hypothetical naval version in order to equip it with the fearsome Fritz X anti-ship guided bomb.

Sources:
1. http://www.luft46.com/arado/are654.html
2. Midland Publishing - Luftwaffe Secret Projects - Ground Assault & Special Purpose Aircraft

Arado Ar.E.581.4

We start this week with another Luft46 project, this time with another "People's Fighter" candidate.

Even if not much is known about the E.581.1, E.581.2 and E.581.3 studies, it's known about the E.581.4 and E.581.5 (which differed from the fourth one in just one detail) which some sketches and technical data survived the war.
It was going to be a jet powered single-seat deep fuselage fighter which was going to be powered by a single Heinkel HeS.011 offering around 12Kn of thrust power feed by a divided air intake located under the cockpit.

It was going to be armed with a pair of 30mm MK 108cannons, the wings were going to be delta shaped with twin fins and rudders on the trailing edge. The landing gear was of a tricycle arrangement.

Arado ceased the work on this design after the RLM issued new requirements and they decided to concentrate in developing their best airplane yet, the Arado Ar.234.

Sources:
1. http://www.luft46.com/arado/are581.html
2. Midland Publications - Luftwaffe Secret Projects - Fighters 1939-1945

Arado Ar.E.381

Today we present you the smallest airplane we have ever drawn.

For the 1944 Jägernotprogramm (Fighter Emergency Programme) Arado presented their E.381 Kleinstjäger (miniature fighter) design to the RLM in November 1944. It was going to be air-lifted in carry-tow to the altittude the Arado Ar.234C.

At a height of 1000m higher than the bombers it was going to be released in order for it to start the initial approach in a high speed shallow dive of around 820km/h (510mph). It could glide for around 20km (12miles) towards the target and it's small size made it a very hard target to hit.

It was presented in three variants all of them sharing some common features.

• E.381/I: It had a circular cross-section fuselage with a small round window in the front in order to let the pilot see through. It was armoured by a 5mm shell and, being as tiny as it was, the pilot had to lie in prone position being the cockpit really cramped. Two bulges were at the sides of the fuselage in order to acommodate the pilot's elbows. By his legs there were two C-Stoff fuel tanks and by his feets a single T-Stoff fuel tank.  The wings were straight and above them there was the 30mm MK108 cannon with 60 rounds which was the only weapon of this airplane. The rocket engine exhausted below the double fin tail. A retractable skid was lowered in order to land it together with a drag parachute that was fitted in a hatch at the top rear. It could only be accessed via a hatch located above the cockpit so the pilot had to enter it before it was attached to the Ar.234C making it impossible to scape in case of an emergency.
• E.381/II: The second variant was identical to the first one albeit a little bit longer. The front canopy was enlarged in order to give a better sight from the still very cramped cockpit. It was also accessed by the top of the fuselage and was also armed with a 30mm MK108 cannon with 45 rounds. It was landed just like the first version, with a skid and a drag parachute. 
• E.381/III: In this version the design was enlarged and the fuselage was shaped like a triangular cross-section, presenting that way an even smaller frontal cross-section. The step for the gun in upper section was eliminated making that way the wing shoulder mounted. The wing tips were turned downwards in order to act as skids when the plane landed and tipped from side to side. Instead of being armed with a cannon, it was armed with six RZ65 or RZ73 spin-stabilized rockets which were fired through the wing leading-edges. The tail was redesigned to place it slightly higher than the fuselage. Both the fin and the rudder were also changed to a simpler rectangular shape. The landing method was the same as the previous two variants. The problem of entering or exiting was partially solved by adding a side-opening hatch located at the starboard of the frontern part of the fuselage.

It was going to be attached to the Arado Ar.234C and, in order to clear the Ar.234 undercarriage upon retraction, it had to be mounted aft of the carrier's center of aircraft. That meant that the E.381 had to give lift from the very beginning of the take-off process. 

Giving the small size and simpleness of the E.381, heat electricity and telephone links were provided by the carrier airplane, this last one was used to help the pilot of the E.381 to make any neede trim changes. 

It was going to be released 1000m above the enemy bomber formations and perform high-speed diving attacks reaching speeds of 825km/h thanks to it's Walter 509B engine which offered a maximum thrust of 2000Kp.
Once landed it was very easy to dismantle it and to load it into a lorry. It took around 600 man-hour to build one but only one mock-up wooden frame was built without any power-plant installed, however it's rumoured that one unmanned prototype was built and flown towed aloft. Anyway, the RLM decided against the parasite fighter program, cancelling every project of this kind.

Sources:
1. https://en.wikipedia.org/wiki/Arado_E.381
2. http://www.luft46.com/arado/are381.html
3. Midland Editions - Luftwaffe Secret projects - Ground Attack & Special Purpose Aircraft.

Arado Ar.440

The technical performance of the the Ar.240 wasn't liked by the Arado company and in 1942 they decided to slightly modify the design. The first prototype was a DB-603G powered Arado Ar.240V2, while the fourth prototype was another DB-603G powered Ar.240V4.

By late November 1942 four prototypes were completed and tested. One of those test pilots was Lt. Werner Thierfelder who, in his final evaluation gave the Ar.440 a very positive rating and wrote that it was an excellent heavy fighter-bomber. However, considering that Luftwaffe had already the Me.410 and Ju.88 in service, they didn't order any Ar.440 even if Arado could start the production of the Ar.440 inmediately using older parts from the Ar.240.

It was powered by two 1874hp (1539hp in combat) Daimler-Benz DB-603G engine with a four-bladed propeller. It was armed just like the Ar.240 with two backward-firing 13mm MG131 machine guns in remote-controlled turrets. In the front part of the fuselage it was going to be armed with two 30mm MK108 gun placed in a pod under the cockpit. In the wings, it could have two 20mm MG151. The pod under the cockpit could be replaced with additional MG131 machine guns. Hardpoints were installed under the middle part of the fuselage in order to make it able to carry up to 1800Kg of bombs or, if needed, aerial cameras.

The maximum speed of the Ar.440 was 700km/h but with the help of the GM1 device it could achieve 750 Km/h. It self-sealing fuel cells in the wings plus a main fuel tank inside the fuselage. It could also carry up to four additional wing-mounted external fuel tanks in order to increase it's maximum range up to 2700km. It was also equipped with a radio direction finder, a shortwave radio, radar altimeter, and a "Friend or Foe" identification device.

Arado presented the Ar.440 to the 1944 emergency fighter program contest but it was won by the Dornier Do.335 "Pfeil".

Sources:
1. https://en.wikipedia.org/wiki/Arado_Ar_240
2. http://www.airwar.ru/enc/fww2/ar440.html (translated)
3. http://www.aviastar.org/air/germany/arado_ar-440.php