XM-1 TANK ENGINE FACT SHEET

PHYSICAL CHARACTERISTICS

Air-cooled Diesel Engine A VCR 1360 [Teledyne Continental]

A proven 12-cylinder, 120° Vee, air-cooled, variable compression ratio diesel engine.

.           1500 HP at 2600 RPM

♦Installed Weight - 7760#

♦Installed Volume - Equal to Turbine

 

Turbine Engine

AGT-1500 [Lycoming]

Sophisticated, recuperative gas turbine with 10 compressor and 4 turbine stages. The 14 rotors are divided between three separate shaft systems. The two compressor stages are concentric systems with the final output being a separate free shaft.

1500 HP at 3,000 RPM

♦Installed Weight - 7840#

♦Installed Volume - Equal to Diesel

♦Includes engine air cleaners and fuel required for a 48-hour battlefield day.

 

VEHICLE PERFORMANCE

It is expected that both engines will provide the XM-l with the automotive performance as required by the vehicle specification.

 

COMPARATIVE ENGINE FACTS

1. The diesel engine is a more thoroughly tested and proven design, less expensive to purchase, more familiar to using troops and very importantly consumes much less fuel than the turbine engine.

a. Testing

Three of the XM-1 diesel engines have completed over 6,000 miles in tank tests. No turbine has gone more than 2,000 miles under similar conditions.

b. Proven Design

The A VCR 1360 engine is based upon the current engine in the M60 tank (the AVDS-1790). The M60 engine is recog­nized as the best tank engine in the world with over 16,000 of these battle-proven engines in service. The turbine engine is based upon an aircraft engine design with no history of ground vehicle use to recommend it.

c.  Low Cost

The diesel has a low acquisition cost of $38,000 versus a reputed $80,000 for the turbine (in 1972 dollars).

d. Familiarity

The AGT-1500 requires complete training of using and logistical support armor units. The Army will require a capability to maintain the current M60 diesel fleet as well as the turbine if it should be selected.

e. Fuel Consumption

The AVCR 1360 diesel will consume 165 less gallons of fuel for a 48-hour battlefield day per tank which is 36% less than the turbine. (This equates to nearly 100 million gallons of fuel a year for 3,300 vehicles in combat or 39,750 GOER 2500 gallon fuel truck loads in logistics train).

 

2. The diesel engine is more reliable than the turbine. One of the major advantages claimed for the gas turbine is greater reliability and durability. This claim is based on commercial aircraft and marine experience. Based on actual Army experience in helicopters, the reliability and durability of the turbine is historically less than the diesel engine in a tank.

Average Operating Hours Before Experiencing a Mission Stopping Failure

AVDS-1790-2D - M60 Tank 427 Hours

T53-L-13B - Cobra Helicopter          226 Hours

After equal years of production, the T53 engine has only half the reliability of the AVDS-1790 when used in a similar type of combat environment.

The AVCR 1360 is predicted to surpass the reliability of the AVDS-1790 used in the M60 tank. The predicted reliability of the turbine in the difficult tank application is really unknown as there is no operating history. It can be expected to be less reliable on the ground than in the helicopter application.

 

3. The diesel engine is easier to keep operating in typical dusty tank environments.

a. The turbine ingests five times more air than a diesel engine. At equal air cleaner efficiency, the turbine will be required to ingest five times the amount of dirt.

b. Recuperative turbines are more sensitive to ingested dirt and will have a lower life than the diesel at equal dirt intake levels. With increased dirt intake turbine life will be greatly reduced. (The Israelis cite this and high fuel consumption as the major reason turbines should not be used in tanks.)

 

4. It is interesting to note that every modern tank in the world, except the Swedish “S” tank, is powered by a diesel engine.

USSR	T-76	800 HP Diesel
FRG	Leopard II	1500 HP Diesel
France	AMX-30	720 HP Diesel
Japan	STB	720 HP Diesel
England	Chieftain	710 HP Diesel
Israel	Tanks	750-950 HP Diesel
♦Sweden	S	300 HP Turbine and 250 HP Diesel as combined power pack

 

250 HP Diesel as combined power pack

 

♦Now want to replace both engines with one diesel of 500 HP due to high fuel consumption, high cost and short life of turbine.

 

5. There is no real weight advantage of the turbine over the diesel.

The high fuel consumption of the turbine engine requires the tank to carry so much more fuel to go the same distance that the touted weight advantage of the turbine is dissipated just to provide the extra fuel.

 

6. What advantage does a turbine have?

a. Low smoke during rapid acceleration which sounds good until one understands that the new diesel AVCR 1360 engine for the XM-1 has better smoke character­istics than the tactically sound and highly successful M60.

b. Lower cooling power required for engine which is only important if the vehicle can be made to perform better. Currently the two vehicles are advertised to perform the same.

 

7. In Summary—Two Questions.

a. Why assume the technical risk, high acquisition cost and high fuel consump­tion of the unproven turbine engine when it is not required for vehicle performance?

b. Why disregard the heritage of the world’s best tank engine for the turbine that has no apparent nor proven advantages for tank applications.