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
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.
It is expected that both engines will provide
the XM-l with the automotive performance as required by the vehicle
specification.
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.
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.
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.
The diesel has a low acquisition cost of
$38,000 versus a reputed $80,000 for the turbine (in 1972 dollars).
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.
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.
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