Newsgroup: it.cultura.militare
Titolo: Pro e contro: Diesel e Turbina a Gas

Pubblico di seguito una lettera inviata a g2mil da un ex-carrista dell'US 
Army.
Molto interessante. Buona lettura!
Pro and Con
I have worked with the M-1, M60A1, M60A3, M48A5 and the M551. I always
looked for the strengths and weaknesses of each vehicle so that I could best
maneuver and fight the tank. There are many good arguments both pro and con
for an M-1 diesel engine conversion, but some of the arguments in the
article are incorrect.
1. I will start with the JP-8 fuel issue; the Army uses JP-8 fuel in all
tactical vehicles in the inventory currently. The only significant problems
associated with this conversion was when regular diesel engines that had
been running #2 diesel for a number of years were switched there were minor
problems across the Army with fuel systems clogging, specifically fuel
injectors. This clogging was caused by particulate that had built up in the
fuel system breaking loose after the switch, as the JP-8 is a much cleaner
fuel that started breaking the old fuel deposits down.
2. The AGT 1500 cost too much to maintain and repair. This on face is
correct, but a great deal of this cost is that the engine is old and worn
out. The AGT 1500 went out of production in the late 1980s. This has
resulted in the Army being unable to do complete rebuilds of engines when
they were returned to the depot and no engines being available to life cycle
out old engines. This has resulted in an ever increasing maintenance load
for this system with the engine that was initially very reliable becoming
the most unreliable and costly engine in the Army inventory. Diesel engines
are not necessarily more reliable. If you take the current engine the AGT
1500 that statement would be correct. When the AGT 1500 first entered
service and was still in production it was far more reliable than its
conventional diesel counterparts that were of a comparable rating and type
of use. When you start looking at reliability comparatives you must compare
like systems of similar age and maintenance programs. The AGT 1500 is on
deaths door not due to an inherently bad or unreliable design, but because
the U.S. Army failed to keep the engine in production or develop a
replacement engine before they ran out of new engine stocks and parts for
complete engine rebuilds.
3. Fuel consumption is too high on the M-1 due to the turbine engine. This
is partially correct the turbine engine has never achieved the fuel
consumption rate of a conventional diesel engine if not operated at a
constant speed this is due to the difference in how the two engines develop
power. There is also a second issue of the age and design of the AGT 1500.
The AGT 1500 was developed in the late 50s. Turbine engines have
significantly improved in the last 40 years if the M-1 were refitted with a
modern turbine engine you could reasonably expect a 35% or greater fuel
efficiency improvement and a reduction in the size and complexity of the
engine. Additionally you would see a decrease in the operational cost of the
fleet reflected by the fuel consumption rate and engine life cycle.
4. A diesel engine will match the performance and capabilities of the
turbine engine. I do not disagree with the argument that a diesel engine
will give the M-1 satisfactory performance. I do disagree with any
assertions that it will match the turbine engine. The diesel and turbine
engine provide power in very different ways and in very few ways are the
operational characteristics of the two engines the same. The diesel engine
is capable of providing massive amounts of torque and horsepower, but it
does this best when the engine is allowed to operate in the lower RPM bands
and when you are not constantly pushing the engine. The best example I can
show of the engines reliability and life cycle difference would be to use
the AVDS 1790 series of engines. The M88A1 and the M48/60 family of tanks
all use this family of engines. The M88 is a recovery vehicle that does not
spend a great deal of time accelerating real hard and trying to sprint
across open areas to the next position as a tank does. The M88 has a very
long life cycle between engine failures the M60 tank on the other hand which
is used for the attack and has periods of long idling or slow movement
followed by sudden acceleration the engine failure rate is much higher. The
engine is the same engine in both vehicles the difference in life cycle is
in how the engine is being used.
5. I do agree that the exhaust heat can be a problem if the vehicles are not
prepared for a joint Infantry/Armor MOUT fight. The heat problem can be
mitigated by the installation of the exhaust diverter that is utilized
during towing by the M-1 being fitted to the main exhaust. The only area of
the rear of the vehicle that has an issue with heat is the center grill
where the main exhaust exits the vehicle. The problem with the fender phone
is easily remedied and is being remedied with the installation of the VIC 3
communications package in the M-1 tank this will take several years. The
interim fix has been the installation of field phones on the outside of the
vehicles.
6. The one issue no one ever talks about with the Armor/Infantry MOUT fight
is the exhaust fumes form the diesel engine. I have extensive time around
diesel vehicles specifically tanks both American and European and the one
problem they all share is extremely noxious exhaust. The one exception to
this is the M-1 tank. If you have never had the pleasure of standing behind
a tank with a diesel engine I highly recommend you do so prior to
recommending the diesel engine as the cure for all that ails the M-1 turbine
engine.
7. Another issue that is never discussed when discussing diesel engine
alternatives to the AGT 1500 is noise. The M-1 tank is the quietest MBT in
the world. The U.S. Army spent a tremendous amount of time and resources
reducing the vehicles noise signature and they have been successful. I have
worked around all of the vehicles that are currently running diesel engines
including the former Warsaw Pact vehicles and there is not an MBT produced
by any country that does not have a very loud engine with the exception of
the M-1. The issue of noise becomes more pronounced with each increase in
power that is forced out of the diesel engine. The AVDS 1790 was relatively
loud, but it never sounded as if it were being forced to produce the power
that it delivered to the vehicle, but with the up powering of that same
engine for use in the M88A2 the noise level increased exponentially. This
problem is true for all of the high power diesel engines either American or
European that have been fitted in vehicles. The more power that is extracted
from an engine the harder it works thus increasing noise and decreasing
engine life expectancy. Even if there were a fender phone on the M-1 tank if
it is fitted with a conventional diesel engine you will not be able to
communicate with the crew inside, the engine even at an idle would be too
loud.
By reading what my points are you might conclude that I am opposed to the
M-1 tank being retrofitted with a diesel engine. I do not disagree with the
installation of a diesel engine, but I believe that the decision must be
based on facts with all the elements considered both pro and con. When I
served on M60 tanks I learned how to make the diesel engine work for me to
overcome some of the vehicles limitations, I was able to put the M60 with a
diesel engine in places where an M1 tank is unable to go because of how the
drive train works, but I also have learned to appreciate the advantages of
the turbine engine and to work around some of the limitations that have been
caused by it.
The single greatest issue facing the M1 tank is the under-funding of
rebuilds, upgrades and repairs. There is a fight going on within the DoD for
the future of the military. This fight is not just within the Army, but
within the Army it has been taking shape for several years. We have spent
billions of dollars to date developing and purchasing the Stryker vehicle.
This vehicle was supposed to be a panacea for all that ails the Army's
ability to deploy and sustain itself once deployed. It was also supposed to
be an off the shelf item which did not require extensive R&D. Unfortunately
neither one of these two stated objectives were true. The end game has been
the dismantling of the Army and reshaping it based on a Light Infantry view
of the world. With the relocation of the Armor center to Fort Benning the
Armor branch within the Army will be phased out or relegated to a marginal
activity that is kept in name only. I hope these dyer predictions do not
come to pass, but I have been following the activities within the Army for
quite some time and believe the Infantry branch has done an excellent job of
playing the politics of the DoD and they will reach checkmate unless someone
within the political realm starts looking at what the DoD is doing and start
asking some very hard questions.
I hope this letter is able to provoke some thought on the topics discussed.
I am not a raving disgruntled tanker who is entrenched in a Cold War
mentality. I was a Light Fighter serving as a Special Forces Engineer and a
Tanker. I served for over twenty years and I always looked for the best way
to accomplish the mission. I study history and see what has and has not
worked in the wars that were fought through the 20th century. I have said
for years that the Army needed to start the development of the replacement
for the M-1 tank and purchase a light tank to replace the M551. I learned to
appreciate the abilities of the Bradley during my time as an OC at Fort
Polk. The much maligned vehicle in the hands of a competent crew in a good
command is an extremely capable vehicle in a MOUT fight. Unfortunately the
other lesson I learned while working at JRTC was the total unwillingness of
the Senior Infantry Leadership to understand utilize and employ the heavy
task force components that they were given. I witnessed the consolidation of
power by the Light Fighters within the Infantry Branch by the elimination of
the 11M MOS. This was done to mask the fact that the 11M were not being
moved into the senior command positions within the branch.
                     Jim Williams
--
Cheers,
Aleks
Dirka dirka Muhammed jihad
shurpa shurpa bakala 

Parla per lo più di difetti di motori diesel anni '60, soliti
americani del cazzo.

 alternatives to the AGT 1500 is noise. (...)
Anche in questo caso è un dato di fatto basato sulla concettualità delle
due macchine.
Un fattore che non è stato considerato è la prontezza di risposta basata
sulle inerzie: a parità di potenza il rateo di incremento di potenza
è molto maggiore per una TAG che per un diesel.
Ma la domanda che mi pongo è la seguente; questa è una analisi basata
su una particolare applicazione, che a sua volta richiede l'analisi
di altre sottoapplicazioni: come è possibile confrontare due sistemi
di produzione di energia così diversi senza un requisito operativo più
chiaro?
Bye, Junker
-- 
Posted via Mailgate.ORG Server - 
http://www.Mailgate.ORG


[...]
*** Grazie della esauriente risposta (barone, prendi ciapa e porta a ca').
Mi domandavo, esistono attualmente alternative ad una tag come la AGT1500? 
Perche' un conoscente di Ft. Benning l'altra settimana mi ha accennato ad 
una probabile sostituzione con un tipo piu' recente, senza tuttavia entrare 
nel dettaglio (per ovve ragioni...).


 *** Grazie della esauriente risposta (barone, prendi ciapa e porta a ca').
Guarda che sono d'accordo con junker, solo che mi sembra veramente
ridicolo riconoscere nei fumi un problema, tra l'altro l'mtu 884 (mi
pare) ossia quello montato sul Puma è anche euro 4 poi le dimensioni
sono estremamente ridotte negli ultimi diesel sempre della mtu

  Guarda che sono d'accordo con junker
*** Mi riferivo alla tua precedente reply, caro LeBaron:
http://img47.imageshack.us/my.php?image=lebaron8jr.jpg
Hai proprio manie di protagonismo, eh?


 
cosa ci posso fare se piaccio a tutti (e soprattutto a tutte)

Sempre da una lettera a g2mil:
Diesel switch not so simple
      The decision to buy a turbine engine tank was a political decision.
The Army had intended to select the GM version, which had a diesel engine.
However, at the eleventh hour, The DepSecDef apparently ordered the Sec Army
to reverse the decision and select the Chrysler version, which had the gas
turbine engine.  You may recall that, at the time, Chrysler was in serious
financial difficulty.  Indeed, it is arguable that had Chrysler not been
able to later sell their tank unit to General Dynamics for $650 million,
they might have
gone bankrupt.
     As for converting the M1 to a diesel engine, not so fast.  When the M1
was first fielded in the Germany, there were serious operability problems
during the winter months due to diesel fuel waxing that plugged the turbine
engine fuel filters. The Army's solution to the problem was to convert to
the use of JP-8, which became available at the time due to efforts by the
Air Force and Army aviation to eliminate JP-4.  The Army now runs nearly all
of it's TO&E equipment on JP-8.
      That said, conversion to a diesel engine powered tank would, in my
mind, suggest another fuel conversion as the diesel tank engine would
certainly perform better running on diesel fuel. Thus the price of poker is
not merely an engine replacement program, but also conversion of a major
portion of the Army and Defense Logistics Agency's petroleum infrastructure/
war reserve fuel stocks as well. How many USMC spaces do you suggest we give
up to pay for that?
           Steve Bliss
                                                                     BG, USA
(Ret)


 nel dettaglio (per ovve ragioni...).
C' era un articolo su RID quest' anno.
Mi pare si proponesse un motore derivato dall'a ttuale,; ovviamente piů
piccolo, piů parco nei consumi, piů facile da manutenere ...
;-)
-- 
Norbert aka Mandos
questo articolo e` stato inviato via web dal servizio gratuito 
http://www.newsland.it/news
 segnala gli abusi ad 
ab...@newsland.it

 C' era un articolo su RID quest' anno.
*** Ah si? Posso chiederti un favore? Potresti, quando hai tempo s'intende, 
rintracciare codesto articolo ed eventualmente passarlo allo scanner?
Thanks Norbert.


 rintracciare codesto articolo ed eventualmente passarlo allo scanner?
Ok, tanto son solo 2 pagine
Se mi dovessi scordare, fra una decina di giorni mandami una mail di
sollecito.
-- 
Norbert - Commissario Aeronautico di complemento in congedo
"La pace è un bene supremo, ma soltanto se fondata sulla giustizia. In 
realtà, se si fa ancella dell'iniquità, della menzogna, della violenza 
diparte, la pace è un alibi per annullare ogni valore e cancellare il 
confine, incerto ma perenne, tra bene e male, e, dunque, anche se 
stessa." (G. Pampaloni)

 sollecito.
*** Sure. Grazie infinite Norbert ;-)


 rintracciare codesto articolo ed eventualmente passarlo allo scanner?
C'è posta per te
-- 
Norbert - Commissario Aeronautico di complemento in congedo
"Did you really believe that this war would end wars?  Well the 
suffering, the sorrow, the glory, the shame  The killing, the dying, it 
was all done in vain,  For Willie McBride, it all happened again,  And 
again, and again, and again, and again."  (Eric Bogle)