Methods to camouflage AFVs

Camouflaging armoured fighting vehicles is an essential task to prevent the vehicle from being detected by enemy forces. Camouflaging can range from basic methods to more layered approaches which cover a wider spectrum of masking. Regardless of the method used, masking an AFV can apply to both ground and aerial detection, which operate in different spectrums of identification. 

Camouflaging methods work in different spectrums against various detection methods. Optical detection can be combated with camouflage paint patterns or netting. Thermal imaging detection can be combated with paint or material that reduces infrared signature/reflection. Lastly, electronic detection (radar), can be defeated with methods consisting of several layers. 
This article will cover commonly seen camouflage methodology present on Soviet and Russian AFVs.

Paint Camouflage 

The most basic method is paint camouflage. Various paint schemes paired with specially designed camouflage patterns can be used to camouflage AFVs and make it more difficult to spot them using day-night observation devices. It is possible to achieve camouflaging by combining different techniques into one single design: colour differentiation between the primary paint coat and secondary paint spots, varying reflection coefficients in the infrared spectrum, and deforming the visible silhouette of a vehicle with a special pattern design. This is the more basic explanation of how this method is formed. Further information on camouflage paint can be found in this article.

Thermal insulation material for masking AFVs

Soviet engineers acknowledged the problem of lacklustre thermal masking back in the early 1970s. The most basic method of reducing thermal radiation on an AFV is to isolate heat sources and cover surfaces which radiate heat (up to maximum temperatures of 700C around the engine compartment).

Experimental work was carried out using a BTR. A thermal insulation layer of polyurethane foam (PPU-304) was applied to the inner surfaces of the hull and on the roof of the engine deck. The BTR's muffler and exhaust were replaced with an ejector-style muffler and exhaust solution designed by VNIITM. The general required results were to reduce radiant intensity (Watt/Steradian, Watt/sr))

Table 1 - Comparative results of experiment and serial production BTR

BTR View	Horizontal axis			Vertical axis
	J, Watt/Steradian		Jser/Jop	J, Watt/Steradian		Jser/Jop
	Production Var.	Prototype Var.		Production Var.	Prototype Var.
Left side	104	49,6	2,1	165,3	120	1,38
Right side	107,8	36,9	2,92	214	75	2,85
Front side	39	12,1	3,07	95,5	75	1,3
Rear side	266	23,7	2,83	261	93,9	2,78

Table 2 - Technical characteristics of polyurethane foam

Parameters			Foam rubber		Parameters		Foam rubber
			PPU-304	PPU-308	Linear temperature decrrease in % at 70C withing 24 hours		PPU-304	PPU-308
Volumetric weight, kg			30-50	40-60			I	I
Strength limit under pressure kg/cm^2			1,5	3,0
Water absobortion within 24 hours, kg/m^2			0,3	0,3	Resistence against acids alkakis		Withstandable	--
Strength limit under bending pressure nore more than, kg/cm^2			2	4,0	Flamability		Self extinguishable, self burning capability duration after removed from fire, not more than 2 seconds
Thermal conductivity coefficient no more than, kcal/m per hour C			0,03	0,03

AFV foam coating camouflage

Various foam-forming formulations can be used to reduce the spotting coefficient of AFVs over a wide range of wavelengths (from optical to radar). A variety of chemical compound foams are available. AFVs can be masked with water-organic, water-polymer hardening, gel-like foams, as well as composite-filled foams. 

Water-organic foams have a wide range of masking capabilities, are easily formed and can be coloured to match the surrounding areas. Foams are applied and removed from objects' surfaces in a simplified manner. 

Water-polymer hardening foams are also characterized by their masking capabilities and availability of components. Such foam coatings have high adhesion to various surfaces and resistance to climatic factors. For the masking of military equipment on the march, foam with a multiplicity of 10-20 retains its masking properties for 5-7 days. 

There is a major disadvantage to these foams in that their preservation rating is extremely short. Such foams quickly lose their masking properties when in contact with rain, wind and other climatic effects. 

Image 1 - External view of a T-80BV with foam coating

Image 2 - Top-down view of a T-80B without foam coating

Image 3 - T-80B without foam coating seen through thermal imaging channel

Image 4 - BTR-80 with foam coating

Image 5 - Comparison between a standard BTR-80 without foam coating on the left and a BTR-80 with foam coating on the right. 

Tank exhaust with reduced thermal signature for gas turbine engine

Tank exhausts are the most powerful source of heat emission and are largely responsible for unmasking AFVs in the IR spectrum. Reducing the level of heat emission of the exhaust presents significant difficulties, especially for vehicles with gas turbine engines. 

Gas turbines operating at nominal power output levels produce exhaust gases which have temperatures of about 500C. The exhaust shutters on GTD exhaust reach temperatures of around 400C. A large area of the exhaust shutters viewed from the rear hemisphere creates thermal masking problems which cannot be solved with standard production exhaust devices which can dissipate heat. In addition, it is viewed that standard exhaust devices have significant aerodynamic resistance to exhaust gases and do not have sufficient armour protection, which eliminates threats like the intake of fragmentation bits entering the turbine. 

A proposed design consists of an inclined armour plate, which rests on the side cheeks, one rotary blade and thermal insulation. The thermal insulation is placed between the blade and the plate on the outside. A distinctive feature of the proposed scheme is the separation of exhaust gas flows and cooling system air, where the cooling system air is exhausted upwards. The exhaust gases are diverted at a 40° angle downwards.

Proposed exhaust design with reduced heat signature properties 

The separation of gas and air flows incorporates the placement of air ducts above the exhaust pipe, due to which the temperature of the engine-transmission deck should decrease. The aforementioned armour protection is achieved with the installation of an inclined plate. The cooling system exhaust has a protective grate which protects against bullet penetration. Anti-radiation protection is ensured by traversing the blade which does not affect exhaust flow. Additionally when equipping the tank with fording equipment, the exhaust device can be hinged upwards and a bridging device is installed on the collar which directs exhaust gases up the fording kit tube. Overlapping armour plates over the air cooling system and significant thermal insulation material thickness, relatively low air temperature of the air cooling system (around 70°C), achieves acceptable thermal radiation characteristics in the rear hemisphere of the tank. 

This proposed design provides a foundation for reducing thermal radiation on gas turbine tanks by normalizing exhaust values. Along with these changes it was considered that the new device also has improved aerodynamics with less drag for exhaust gasses. 

Camouflage kits

In addition to camouflaging AFVs, camouflage kits provide an extra layer of concealment. Camouflage kits typically consist of a mesh base webbing with fabric pieces woven into patterns. MKT series of camouflage netting is used for covering stationary targets such as AFVs or other installations. "Ternovnik" is a more specialized camouflage kit found on modern Russian AFVs. 

Image 1: MKT-2L (summer) - MKT-2S (snow) - MKT-4P (desert)

Image 2: Camouflage kit fragments

The Ternovnik is a carpet-style camouflage kit used with the Nakidka, a protective multi-spectral tarp. Ternovnik is classified as a 'quasi chaotic forming structure' made from metallized fabric pieces. The kit comes in one-, two-, and three-colour patterns and can be painted green, light green, or black. Ternovnik is produced in 2 variants, single layer (Ternovnik-TG-MO, Ternovnik-TG-MO-20, Ternovnik-TG-2MO) and double layer (Ternovnik-2TG-MO/MO, Ternovnik-2TG-MO-20/MO, Ternovnik-2TG-MO/2MO).

T-90 fitted with Ternovnik

References: 

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