Ar-2 technical description
by Massimo Tessitori
updated on May 6, 2006                                file name: technical.html
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Fuselage structure
The fuselage structure of Ar-2 is basically identical to that of SB, that is to say a metallic structure with duraluminium riveted skinning.
The fuselage hosts the crew compartments (navigator, pilot, gunner) and the bomb bay.
The covering of the top fuselage between 4-th and 8-th frames was carried out from "balenit", the plywood pasted by VIAM glue to wooden carrying parts of 5-th, 6-th and 7-th frames.
Pilot cockpit
the seat of the pilot was moved on the left, while the instruments panel was moved on the right to allow the pilot to see through the windows of the navigator at landing and on a dive;
there was a PBP-1 sight (for dive bombing) in the pilot's cabin;
there were a diving gyro artificial horizon and an overload alarm on the pilot's instrument panel.

Navigator cabin
It was housed in a new glazed nose, with better penetration that the one of SB.
There were duplicate flying controls in the navigator's cabin to increase survivability; beside, the aircraft can be used as a trainer without need to replace all the nose to add a pilot cockpit as on USB.
There were an NKPB-3 sight (for bombing at night and from small altitude) and an OPB-1 sight, both in the navigator's cabin.

Nose ShKAS was installed in a new spherical installation called NU-DB-3F with 500 cartridges for the navigator; its firing field was a cone of 50°.
The bullet feeding was made by a flexible guide on the right side. 
A thin vertical rod was used to lock the machine gun in flight position. 
The large rectangular windows low on the left side were for the pilot, that looked at the ground through them before diving.

rear gunner/radio operator cabin 
Dorsal ShKAS  was in dorsal installation TSS-1 (1000 cartridges), and was equipped with reflector sight K-8T; the installation TSS-1 had a field of fire of 90 degrees to the left and to the right, of 60 degrees upwards and of 30 degrees downwards.
The turret TSS-1 was an half ring on which the carriage with a head of a machine gun moved. 
In cruising position, the machine gun settled down on the left board; for this purpose there was a small cut on the left side of fuselage (only in prototypes; in series aircrafts it doesn't appear) . 
In shooting position, the transparent screen of the turret moved on rails forward and rose a little upwards, protecting the gunner from a pressing air stream. 
While on early Ar-2s the transparent screen was symmetrical apart for a small metal plate on the left rear lip (photo on the right), on series aircraft the structure was slightly asymmetrical. Besides, the cut on the fuselage was smaller and oblique instead than vertical, and the gun barrel recess has disappeared. (photo below). 
It is not clear how the gun barrel was located with the late type hood in closed position; probably it was at 6 o'clock in central position, but it could have been in any position when the trasparent nail was removed..
In facts, many of the photos of operative Ar-2s show that the rear trasparent nail was partially broken or removed. 

few images show aircraft without the hood at all: perhaps it was removed because it was difficult to be opened in flight, as on MiG-3s.

ShKAS (image Lee Jong Tae)

The ventral ShKAS  with sight OP-2P was placed inside a retractable fuselage turret MB-2 with a magazine of 600 cartridges; its firing field was of 30 degrees to the left and to the right and from 4-5 up to 55 degrees downwards.

Images of the dorsal gunner position of late type from both sides. 
Note the slight asimmetry of the frames.
Probably a space to protrude the gun remained between the sliding hood and the fuselage on the right side.
Note that the frames of the ventral position doors are asymmetrical too.

No photos of Ar-2 bomb bay are available; however, it should be nearly identical to that of SB, except for the use of two PB-3 horizontal bomb racks instead of DER-23.
These two images are of an SB bomb bay.
(from Tupolev SB in action)

The image on the right, from the front, shows a six-cell container for FAB-100 bombs, that were loaded nose up and secured to DER-34 bomb racks.
Actuators for doors were located both on th front and on the rear of the bay. 
The rear part appears without further charges.

The image on the left (from the rear) shows two bombs in vertical position (probably FAB-50), and a dismountable platform with two DER-23 bomb racks (probably replaced by two PB-3 on Ar-2), able to carry two FAB-250 bombs in horizontal position, or one FAB-500 on its right side rack only.


Here are some possible load combinations for Ar-2:

Besides, there was the possibility to bring underwing  two containers VAP-500 and/or two UHAP-500 that can carry all types of poisonous gas, incendiary and smoking mixes.
Despite the availability of large amounts of Yprite and other gases in Soviet inventory, chemical weapons were never used against Germans for fear of a reprisal.

(here depicted on a SB; images from Tupolev SB in action)


The wing was divided in three parts: a central one, and one external console for each side. All the wing was streghtened by two longarons.
All the skinning was made by riveted duraluminium sheet, apart for the ailerons that had a duraluminium structure with fabric skinning.
The central part of wing, supporting the engines and the landing gear, was more or less identical to that of SB; its structure was partially made of steel tubes passing through the fuselage. Two fuel tanks were housed between the longarons.
The flaps were wider than those of SB.
Two PB-3 bomb racks were installed on each side, internally to the engine gondolas. Each one was provided with a wire for bombs loading.
The outer wing consoles were smaller and of simplified construction if compared to those of SB. The right aileron only had a trim tab.
There was a 330-l fuel tank in each wing outer console.
There were air brakes (as on Ju-88) under the wings; these brakes were extended by rotating forward; their extension was mechanically signaled to the pilot by indices rising from the wing uppersurface between 10th and 11th wing frames.
A landing light was installed on the left wing only.

Power plant
The Ar-2 was moved by two Mikulin M-105R engines, moving two VIT1T-22E propellers with 3.1 m diameter; both props turned clockwards (seen from the front). 
The reduction rate of engine gears was 0.59.
The engine nacelles were particularly aereodinamical; to improve penetration, the water and oil coolers were installed in the wing thickness.
The supercharger intake was located under the nacelles. 
On this photo, the left supercharger intake appears closed by two small doors that open by rotating on central hinges when the landing gear is retracted to prevent ingestion of any solid object. This device doesn't appear on most photos of operative Ar-2, and not even on the other engine on this photo.
Water coolers were in tunnels inside the wing thickness, with inlets on the wing leading edge, and outlet on the wing uppersurface closed by 5 adjustable flaps (6 on prototypes).
There was a new lubrification system, with a water-oil cooler and a air-oil one on each engine; the air-oil had a circular intake on the wing leading edge.
The exhaust stacks were made by a couple of pipes  for each engine; they pass through the wing, discharging fumes on the wing upper surface, as on SB-2M103. 
They were shaped to give some thrust.

Main landing gear
The landing gear was identical to that of SB  and the main wheels protruded through openings on their doors, but the nacelles were closed on the back, differently than on SB.
The side rods of the leg were connected to the bay doors, that were moved by the leg retraction/extraction movement.

Tail surfaces
The tail surfaces had metallic frame and duraluminium skinning. The elevators and rudder had a duraluminium structure covered with fabric skin.
Each tail horizontal surface was streghtened by 3 wires, two (the lower ones) joined to the fuselage, and one (the upper one) to the stabilizator.
Both the rudder and elevators had trim tabs.

Note: the most of the images of this page are from M-Hobby 3/2003, a work of M.Maslov and N.Polikarpov
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