The T-64BV MBTs of the Ukrainian Armed Forces reserves in winter camouflage

Exercise of the tank reserves of the Armed Forces of Ukraine were held in the Donetsk region. During training, the crews trained to moving out of the concentration area to the firing line, maneuvers as part of a company against a possible enemy, and performing tasks in conditions of a sudden change of the situation.

Source Joint Forces Operation

The documents about the front hull special armor the basic M1A2 tank used

Damian Ratka have found very interesting data about the basic M1A2 hull frontal armor package.

The two interesting sources at DTIC archives, that might answer us what type of front hull special armor the basic M1A2 tank used. These sources are Ballisticians in War and Peace vol.3 and The U.S. Army Laboratories at Watertown, Massachusetts.

First document from Ballisticians in War and Peace vol.3 says to us that BRL (Ballistic Research Laboratory) developed special armor for M1A2 hull front providing 35% more KE and 25% more CE protection vs original M1A1 front hull armor.

The secend document is the U.S. Army Laboratories at Watertown, Massachusetts document, provides us information that Watertown with BRL developed in 1988-1991 timeframe a tandem ceramic armor that provided 33% increase in protection vs KE threats. Coincidence? I don't think so.

So we might safely assume, that while basic M1A2 used Heavy Armor Package with DU alloy in turret, hull used Tandem Ceramic Armor Package. 

Sources:

Ballisticians in War and Peace

THE U.S. ARMY LABORATORIES AT WATERTOWN, ASSACHUSETTS - CONTRIBUTIONS TO SCIENCE AND TECHNOLOGY: A HISTORY

P. S. Some data about Abrams armor:

ტანკების ჯავშანდაცვა - NATO vs СССР

დასავლეთის ტანკების ჯავშანდაცვა (Abrams M1, Leopard-2, Challenger 1/2 და Leclerc)

ოფიციალური დოკუმენტი M1 Abrams-ის კომპოზიტური ჯავშნის შესახებ

ტიტანის ჯავშანი - ანუ როგორ შევამციროთ Abrams-ის წონა

INDIRECT FIRE CONTROL INSTRUMENTS FOR THE M41A3, M48 AND M60 TANKS

Auxiliary Fire Control Instruments

The auxiliary fire control instruments are designed to complement the direct-fire control system in providing the tank crew with a 24-hour capability of delivering effective fire. The instruments are primarily used to obtain and apply range card data for the tank's armament and searchlight. If the tank is used in the artillery role then the instruments are used to apply firing data from the fire direction center. The instruments used in this system consist of a gunner's quadrant or elevation quadrant and an azimuth indicator.

P. S. The US Army had this extra gear installed all the way up to the M60 tanks. 

Gunner's Quadrant

This instrument (fig. 1) is OEM on all standard tanks. It is used to measure and apply angles of elevation on those tanks without mounted elevation quadrants. On main battle tanks this quadrant is used primarily to check and adjust the mounted elevation quadrant. In measuring and applying angles, it is possible to interpolate the reading of this quadrant to the nearest one-tenth of a mil. There are two scales on this quadrant: the elevation scale graduated in 10-mil increments, and the micrometer scale graduted in increments of two tenths of a mil. Each scale has an index to designate readings. A level vial is mounted on the index arm. To measure or apply plus angles of elevation, the black line-of-fire arrow must be pointed to the muzzle end of the main gun. Minus angles are measured or applied with the black line-of-fire arrow pointing to the breech end of the gun. To use the quadrant to measure or apply angles of elevation, the quadrant shoes are placed on the seats or scribed marks provided on the breechring of the main gun. The index arm and micrometer knob or the gun controls are manipulated to obtain the proper reading. The quadrant must be checked periodically for accuracy by the end-for-end test. If the correction is greater than 0.4 mil it must be turned in to Ordnance.

Gunner's Quadrant (fig. 1)

Elevation Quadrant

This instrument (fig. 2) is found only on the main battle tanks and is used to measure and apply gun elevation angles. Elevation angles can be measured and applied to the nearest 1 mil. It is mounted on the ballistic drive cross shaft or on the recoil guard of the main gun. The elevation quadrant has two scales: the elevation scale graduated in 100-mil increments and the micrometer scale graduated in 1-mil increments. Black figures indicate plus readings and red figures minus readings. Each scale has an index to designate readings. The quadrant has a level vial and a reflector to aid the gunners when centering the bubble. Elevations are applied or determined by rotation of the micrometer knob and use of the gun controls. The elevation quadrant is checked and adjusted by using the gunner's quadrant.

Elevation Quadrant (fig. 2)

Azimuth Indicatora

The azimuth indicator (fig. 3) is used to lay the gun for direction and to measure horizontal angles. It is mounted so that its gear meshes with the turret ring gear and is located on the right side of the turret where it can be viewed by the gunner. The azimuth indicator has three scales: an azimuth scale graduated in 100-mil increments, a micrometer scale graduated in 1-mil increments, and a gunner's aid scale graduated in 1-mil increments. There are three pointers: an azimuth pointer (middle) and a micrometer pointer (outer), both of which are adjustable, and a directional pointer (inner). The directional pointer indicates the amount of turret traverse measured from the front center of the tank and is nonadjustable. To use the azimuth indicator, the gun is laid on a reference point by use of the direct-fire sights. The resetter knob is pushed down and rotated to move the azimuth and micrometer pointers to zero, then released. Any subsequent turret rotation will be measured by the azimuth and micrometer scales. For small shifts (50 mils or less) in deflection, the gunner's aid is rotated to index the zero of its scale opposite the micrometer pointer; then the turret is traversed in the desired direction until the micrometer pointer indicates the required deflection angle on the gunner's aid.

b. Azimuth indicators must be checked peri-odically for accuracy and slippage. As no error is allowable, inaccurate instruments must be repaired by Ordnance.

The azimuth indicator (fig. 3)

Source: FM 17-12 TANK GUNNERY (1964)

Gross and Net HP of Tank engines

Horsepower is officially defined as "the amount of energy required to lift 550 pounds, one foot, in one second." This definition dates back to when cars didn't even exist and, despite the worldwide acceptance of the metric system (America not withstanding) in which feet have been replaced by meters, the definition remains in use today.

Generally speaking, horsepower is an indication of how capable a vehicle is at moving itself around and, consequently, the more horsepower a vehicle possesses, the quicker it can move between two points. In addition to determining how quickly a car or truck can move, horsepower has a direct relationship to top speed. As a vehicle's speed rises, additional horsepower must be expended to push it.

So if the definition of horsepower is so straightforward (550 pounds moved one foot in one second), how can the same vehicle have different horsepower ratings? For instance, Leopard-2 MBT have the 47.6-liter  MB-873 Ka-501 engine at 1500 horsepower. Yet  in realiti the tank  has 1252 horsepower. So what gives?

Gross output, is the output of a ‘bare’ engine running on a test stand with no external engine-driven accessories (e.g., alternators or water pumps), free-flowing exhaust headers with no mufflers, and optimal ignition timing. Gross ratings are also mathematically corrected for standard atmospheric conditions. In other words, gross output represents a particular engine’s maximum output under ideal conditions.

Net hp is what the engine is capable of in a car. It is also taken on an engine dyno at the flywheel, but with the engine equiped as it would be in the car. Stock air filter assembly, cooling system, stock exhaust mainfolds running through stock mufflers, various engine-driven accessories, including the engine’s own water pump and generator/alternator and add-ons like the power steering pump and air conditioning compressor. Engines intended for on-road use typically also have restrictive air cleaners and exhaust systems, sound-deadening mufflers, and emissions-control add-ons like catalytic converters and thermal reactors. Engine tuning is further compromised in the interests of reduced noise, better drivability, improved cold-weather performance, and lower exhaust emissions. All of these factors reduce the engine’s maximum output in ways that the gross rating methodology does not reflect. 

Below we can see Gross and net HP of different tank engines

Inflatable K1A1 and M1A1 at ADEX 2017

 Inflatable K1A1 and M1A1 at ADEX 2017

K1A1

On the table is wrote K1A1, but its looks like M1 Abrams

K2 Black Panther inside and outside

K2 Black Panther inside

Gunner's compartment

Commander's compartment

Other inside details 

Walk around

First batch of upgraded T-90M ‘Proryv’ tanks delivered to Russian troops

Russian Army has taken delivery of the first of new T-90M ‘Proryv’ main battle tanks, according to Army Commander Major-General Sergey Kisel.

First deliveries of T-90M ‘Proryv’ tanks started in April to the Kremlin’s elite Taman Division.

A first batch of Russia’s upgraded T-90M ‘Proryv’ main battle tanks have been delivered to Russian troops, the press service of the Russian Western Military District announced on Monday.

"First deliveries of upgraded T-90M ‘Proryv’ tanks started in April to the Guards Tank Army of the Western Military District, which is deployed on the territory of five Russian regions," the press service quoted Army Commander Major-General Sergey Kisel as saying.

The T-90M ‘Proryv’ has received a principally new turret that differs from the serial-produced module and a more powerful engine. The Proryv is outfitted with a new multi-channel sighting system that allows employing weapons at any time of day or night and, as its major advantage, it can exchange data with other vehicles in real time.

The T-90M’s armor features special anti-slip coating similar to that used on the latest T-14 Armata tank.

Last month, a source in the Russian Defense Ministry told TASS that T-90M ‘Proryv’ tanks would pass through Red Square for the first time in a mechanized column during the Victory Day Parade on May 9.

The mechanized column is also set to include the latest T-14 ‘Armata’ tanks. Overall, more than 50 tanks were supposed to take part in the military parade on Moscow’s Red Square, according to the Defense Ministry’s previous data.