comparing russian and US jet engines OH times

[old hoodoo]

I just read where Russian Su-30 engines are intended to operate 300 hours
before major overhaul. How do US engines compare? 300 hours seems awfully
short to a layperson like me.

Al

[Tarver Engineering]

"old hoodoo" > wrote in message
...
> I just read where Russian Su-30 engines are intended to operate 300 hours
> before major overhaul. How do US engines compare? 300 hours seems
awfully
> short to a layperson like me.

I can only speak to our J-75s, but it was teardown inspection and repair
every 400 hours; depo overhaul each 1200 hours.

[Larry]

The J-52's currently flown in the Navy's EA-6B Prowlers go 1,000 between
overhauls.

Interestingly, I understand that motor was intended as a "disposable" motor
designed originally for a missile program.


--
(¯`·._.· £ãrrÿ ·._.·´¯)


"old hoodoo" > wrote in message
...
> I just read where Russian Su-30 engines are intended to operate 300 hours
> before major overhaul. How do US engines compare? 300 hours seems
awfully
> short to a layperson like me.
>
> Al
>
>
>

[Smartace11]

>
>I just read where Russian Su-30 engines are intended to operate 300 hours
>before major overhaul. How do US engines compare? 300 hours seems awfully
>short to a layperson like me.

The whole engine doesn't get overhauled, just modules. Each module, ie fan,
compressor, turnine, fan drive turbine, etc has a different interval, usually
based on cycles, ie temperature excursions from cold to hot.

Fighter engines typically stay installed for 300-600 hours on average and come
off for repair not overhaul.

The Soviets/Russians have always made disposable fighter engines from what I
know. Run'em hot, burn'em up, then salvage/overhaul them. Eliminates most of
the logistics tail and cuts way down on traing requirements. Gues you can do
that when you own the world's supply of titanium ore and most of your troops
are illiterate.

[Chad Irby]

In article >,
(Smartace11) wrote:

> The Soviets/Russians have always made disposable fighter engines from what I
> know. Run'em hot, burn'em up, then salvage/overhaul them. Eliminates most of
> the logistics tail

....up until week two or three, when you're out of engines, and your
depots are all smoking ruins...

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.

[Guy Alcala]

Chad Irby wrote:

> In article >,
> (Smartace11) wrote:
>
> > The Soviets/Russians have always made disposable fighter engines from what I
> > know. Run'em hot, burn'em up, then salvage/overhaul them. Eliminates most of
> > the logistics tail
>
> ...up until week two or three, when you're out of engines, and your
> depots are all smoking ruins...

The Soviet idea was that combat a/c in a major war weren't going to last that long
in any case, so the engines had to have enough remaining TBO in them (on average,
50% of their total TBO) when the ballon went up, enough to to last until they were
lost. Replace the whole jet with reserve a/c. In peacetime, it made more sense for
them, given their economy and infrastructure, to concentrate the highly-skilled
techs at the factories rather than disperse them out to the units.

Sukhoi, MiG and others have been pushing the engine companies to to improve the
engine TBOs, so that western and western-oriented airforces will be more willing to
buy them. Many of the joint venture commercial transports have been offered with
western engines, for the same reason. They've still got a ways to go, as ISTR the
F100 has a TBO of 4,000 hours now, and IIRC the most modern engines are intended to
have only on-condition maintenance between overhauls, but I'll leave it to others
with more knowledge and experience to confirm or deny that.

Guy

[Paul J. Adam]

In message >, Chad Irby
> writes
>In article >,
> (Smartace11) wrote:
>> The Soviets/Russians have always made disposable fighter engines from what I
>> know. Run'em hot, burn'em up, then salvage/overhaul them.
>>Eliminates most of
>> the logistics tail
>
>...up until week two or three, when you're out of engines, and your
>depots are all smoking ruins...

Come on, you must have seen it...

Two Soviet tank marshalls sipping champagne on the Champs-Elysees,
watching the Red Army's victory parade. One asks the other "So who _did_
win the air war?"

If they could dispute air superiority long enough for the Massive
Armoured Spearheads(TM) to smash their way to the objective (the Ruhr?
The Channel?) they win. Same reason the tanks were only designed for
short lives... who cares, they'll be destroyed before then anyway.

Now, with hindsight that plan worked a lot better in theory than in
practice... but it worked for them in the Great Patriotic War, and the
West was hoping to "be the Germans but win" in a Central Front rematch.


--
When you have to kill a man, it costs nothing to be polite.
W S Churchill

Paul J. Adam MainBox<at>jrwlynch[dot]demon{dot}co(.)uk

[Smartace11]

>Sukhoi, MiG and others have been pushing the engine companies to to improve
>the
>engine TBOs, so that western and western-oriented airforces will be more
>willing to
>buy them. Many of the joint venture commercial transports have been offered
>with
>western engines, for the same reason. They've still got a ways to go, as
>ISTR the
>F100 has a TBO of 4,000 hours now, and IIRC the most modern engines are
>intended to
>have only on-condition maintenance between overhauls, but I'll leave it to
>others
>with more knowledge and experience to confirm or deny that.
>
>Guy
>
>
>
>

Sounds about right for the turbine. At 2.0 - 2.5 thermal cycles per operating
hour, 4000 hours is about 8,000 - 10,000 cycles. The compressor and fan run
quite a bit longer, hence the modular maintenance approach. When one module
reaches its limit it iw replaced, not the entire engine. There are also
intermediate inspections up until the end of the life cycle, but those are
mostly for inspection, not replacement except for certain parts like shrouds
and combustors.

Pretty much the same aproach to maintenance in high bypass fans in the heavies,
too though they accumulate thermal cycles more slowly, something around 1.0 or
less because of far fewer throttle transients.

Different approach for engines like the TF33 in the B-52 and C-141 because
those are not mudular engines. The entire engine has a TBO on them, but in
those application it is almost more of a fly to failure.

[Smartace11]

>) to smash their way to the objective (the Ruhr?
>The Channel?) they win. Same reason the tanks were only designed for
>short lives... who cares, they'll be destroyed before then anyway.
>
>Now, with hindsight that plan worked a lot better in theory than in
>practice... but it worked for them in the Great Patriotic War, and the
>West was hoping to "be the Germans but win" in a Central Front rematch.
>
>
>--
>When you have to kill a man, it costs nothing to be polite.
> W S Churchill
>
>Paul J. Adam MainBox<at>jrwlynch[dot]demon{dot}co(.)uk
>
>
>
>

That worked okay when the technology wasn't so expensive. Now stuff is so
expensive that it can't be used as cannon fodder.

I suspect the main problem with the Russian engines is that they have the
turbine inlet temp cranked up really high to produce thrust but haven't gotten
around to using advanced metals and ceramics on the blades and vanes in those
areas so they lose efficiency quickly. Reducing TIT would give more life to
the engines but less thrust.

Same issue with the J79 in the 60s and 70s. They smoked like crazy. The TIT
could be turned up but the life of the engines would be reduced significantly.
There was a combuster mod in the 80s that reduced the smoke a great deal.

One thing about flying a "smoker" was that you had far less of a chance of
being mistaken for a MiG. On the other hand you were also MiG bait but with
numerical superiority in the theaters the F-4 operated, the problem wasn't that
significant.

[The Enlightenment]

(Smartace11) wrote in message >...
> >
> >I just read where Russian Su-30 engines are intended to operate 300 hours
> >before major overhaul. How do US engines compare? 300 hours seems awfully
> >short to a layperson like me.
>
> The whole engine doesn't get overhauled, just modules. Each module, ie fan,
> compressor, turnine, fan drive turbine, etc has a different interval, usually
> based on cycles, ie temperature excursions from cold to hot.
>
> Fighter engines typically stay installed for 300-600 hours on average and come
> off for repair not overhaul.
>
> The Soviets/Russians have always made disposable fighter engines from what I
> know. Run'em hot, burn'em up, then salvage/overhaul them. Eliminates most of
> the logistics tail and cuts way down on traing requirements. Gues you can do
> that when you own the world's supply of titanium ore and most of your troops
> are illiterate.

The Russians have a different maintenance philosophy. All of their
maintenance is meant to be done in the field. There is no return to
the depo or factory style maintenance at all therefore their field
maintenace looks more frequent compared to western methods which are
infrequent but then have a huge overhaul back at depo or factory
level.

There is a big difference in philosophy and you aren't comparing
apples with apples but rather apples with oranges.

It probably would require some scoreboarding on a spreadsheet.

I can understand the Russian reasoning: the USAs military and
procuremewnt philosophy is based on the assumption that CONUS and its
depos and factories will not come under air attack, and the US
airfields overseas will also be free due to US air superiority. The
Russians don't have that luxury becuase they are or were withing close
distance of lots of hostile nations in Eruope, Near East and Far East.
They have thus have to develop more autonomy andf built to lower
levels of skills and field equipement.

The Russian literacy is probably much better than US literacy.

[Pete]

"The Enlightenment" > wrote
>
> The Russian literacy is probably much better than US literacy.

Right.

In 20 yrs in the USAF, I came across 1 (and only one) guy who was
functionally illiterate. Reasonably smart, but the poor guy could not read.

How does this contrast with Russian conscripts who may be drawn from a wide
range of native languages?

Pete

[Yama]

"The Enlightenment" > wrote in message
m...
> There is a big difference in philosophy and you aren't comparing
> apples with apples but rather apples with oranges.

I've never quite got that metaphor. Oranges are much superior.

[Yama]

"Pete" > wrote in message
...
> "The Enlightenment" > wrote
> >
> > The Russian literacy is probably much better than US literacy.
>
> Right.
>
> In 20 yrs in the USAF, I came across 1 (and only one) guy who was
> functionally illiterate. Reasonably smart, but the poor guy could not
read.
>
> How does this contrast with Russian conscripts who may be drawn from a
wide
> range of native languages?

In theory, school standards were same across the USSR, so all were taught to
read. Whether in practice this meant that everyone really could read
Russian, I don't know.

On average, conscript armies probably have "smarter" personnel as you get to
draft all the truly smart ones. On the down side, you get all the dumb ones
too (and there were some _really_ dumb ones, I can tell...).

[Smartace11]

>
>There is a big difference in philosophy and you aren't comparing
>apples with apples but rather apples with oranges.
>
>It probably would require some scoreboarding on a spreadsheet.
>

The benefits and disadvantages of two vs three level maintenance (flightline
-depot, flightlne-intermediate ship-depot has been studied to death and
scorecarded). As an analyst and engineer in an overhaul depot and propulsion
systemprogram office, I gathered data and did the analysis myself.
For most of the world, the most efficient means of maintaing jet engines has
proven to be three level. Even in Israel where the battle front is not more
than one hundred miles away fro the bases, three level is employed.

I misspoke on Russian literacy. I should have said Soviet/Russian enlisted
ranks, the people who do the maintenance. This has been a point made in
numerous publications and always considered to be a weakness of the Soviet
military. I am not prepared to say how much of a problem it is in the Russian
military but I suspect it is still a problem considering where the men are
drawn from.

>I can understand the Russian reasoning: the USAs military and
>procuremewnt philosophy is based on the assumption that CONUS and its
>depos and factories will not come under air attack, and the US
>airfields overseas will also be free due to US air superiority. The
>Russians don't have that luxury becuase they are or were withing close
>distance of lots of hostile nations in Eruope, Near East and Far East.
> They have thus have to develop more autonomy andf built to lower
>levels of skills and field equipement.
>
>The Russian literacy is probably much better than US literacy.
>

[Smartace11]

>In theory, school standards were same across the USSR, so all were taught to
>read. Whether in practice this meant that everyone really could read
>Russian, I don't know.
>
>On average, conscript armies probably have "smarter" personnel as you get to
>draft all the truly smart ones. On the down side, you get all the dumb ones
>too (and there were some _really_ dumb ones, I can tell...).
>
>

You are assuming the smarter ones want to be there and are motivated, something
that wasn't the case before the all volunteer military in the US



>
>
>
>

[tadaa]

> I misspoke on Russian literacy. I should have said Soviet/Russian
enlisted
> ranks, the people who do the maintenance. This has been a point made in
> numerous publications and always considered to be a weakness of the Soviet
> military. I am not prepared to say how much of a problem it is in the
Russian
> military but I suspect it is still a problem considering where the men are
> drawn from.

I doubt that Soviets used unreliable and worst educated people of southern
SU in more important places (nukes, air force). They had large enough pool
to draw literate men to more demanding jobs.

My understanding is that SU used southeners and such in low grade infantry
units.
I'm not claiming that their mechanics were highly trained professionals, but
illiterate might not be the right description either.

[WaltBJ]

Don't know a hell of a lot about Russian enlisted men except that
until they develop career NCOs no two-year enlistee/draftee is going
to become much of an expert on any sphere of maintenance (roads &
grounds?). That leaves officers and warrant officers as the career
technicians.
As for airliner engines - they run 'on-condition' with a very clsoe
watch on operating parameters. I used to keep tabs on CF6s and RB211s
and the crew entered steady-state operating parameters for each
flight. This was hand-massaged with a special whiz-wheel to normalize
the readings to STP and then graphed. The trend graphs plus oil
spectrometric analysis afforded a pretty good assurance that an
adverse trend would allow detect of trouble well before it got
serious. Nowadays all this is recorded and fed into computers which
avoids a lot of hand work. BTW 15,000 hours in continuous service on
the airframe is not a record for RB 211s. One reason is that they are
babied and operated at something like 80% of maximum rated thrust. For
instance, where I worked the engines were idled 5 minutes after start
to normalize temps before adding power. And also idled 5 minutes prior
to shutdown, also to normalize the temperatures. It paid off big-time.
Walt BJ

[Vaughn]

"Pete" > wrote in message
...
>
> "The Enlightenment" > wrote
> >
> > The Russian literacy is probably much better than US literacy.
>
> Right.
>
> In 20 yrs in the USAF, I came across 1 (and only one) guy who was
> functionally illiterate. Reasonably smart, but the poor guy could not
read.

Likewise, I came across only one in the US Navy. They discharged him
after 4 weeks of boot camp.

Vaughn

[Pete]

"Vaughn" > wrote

> >
> > In 20 yrs in the USAF, I came across 1 (and only one) guy who was
> > functionally illiterate. Reasonably smart, but the poor guy could not
> read.
>
> Likewise, I came across only one in the US Navy. They discharged him
> after 4 weeks of boot camp.
>

hehe. This guy was a motorpool type E-5. Maybe 13 yrs in. We sent him to
reading classes.

Pete

[Alan Minyard]

On 15 Dec 2003 13:51:32 GMT, (Smartace11) wrote:

>
>>
>>There is a big difference in philosophy and you aren't comparing
>>apples with apples but rather apples with oranges.
>>
>>It probably would require some scoreboarding on a spreadsheet.
>>
>
>The benefits and disadvantages of two vs three level maintenance (flightline
>-depot, flightlne-intermediate ship-depot has been studied to death and
>scorecarded). As an analyst and engineer in an overhaul depot and propulsion
>systemprogram office, I gathered data and did the analysis myself.
>For most of the world, the most efficient means of maintaing jet engines has
>proven to be three level. Even in Israel where the battle front is not more
>than one hundred miles away fro the bases, three level is employed.
>
Interesting, since the USN decommissioned all of its afloat IMA s and most
(if not all) of its shore based IMA s. This despite the fact that the vast
majority of ships now have "aircraft" engines, the LM2500 and derivatives.

Al Minyard

[Smartace11]

>Interesting, since the USN decommissioned all of its afloat IMA s and most
>(if not all) of its shore based IMA s. This despite the fact that the vast
>majority of ships now have "aircraft" engines, the LM2500 and derivatives.

Suspect that the operating cycle for ships is about the same as for airliners
or even transcontinental pipeline pump power units that alsu use variations of
aircraft turbine engines. They tend to run forever since they are started and
run at the same power setting all the time. When they accumulate enough time
or on-condition mauintenance analysis indicates they are losing efficiency
(increased fuel flow and increasing temps in the hot section) they are pulled
and sent to depot. The maintenance concept is usually driven by usage.
Fighters tend to use up life in their engines far quicker than any other
application and require more maintenance. Most of what I have offered has more
to do with fighter engines than anything else since the originator of the
thread mentioned the Su-30.

[Bjørnar Bolsøy]

"Pete" > wrote in
:
> "The Enlightenment" > wrote
>>
>> The Russian literacy is probably much better than US literacy.
>
> Right.
>
> In 20 yrs in the USAF, I came across 1 (and only one) guy who
> was functionally illiterate. Reasonably smart, but the poor guy
> could not read.
>
> How does this contrast with Russian conscripts who may be drawn
> from a wide range of native languages?
>
> Pete

Russia: 99.6%
US: 97%

http://www.cia.gov/cia/publications/factbook/geos/rs.html#People
http://www.cia.gov/cia/publications/factbook/geos/us.html#People



Regards...

[Pete]

"Bjørnar Bolsøy" > wrote in message
...
> "Pete" > wrote in
> :
> > "The Enlightenment" > wrote
> >>
> >> The Russian literacy is probably much better than US literacy.
> >
> > Right.
> >
> > In 20 yrs in the USAF, I came across 1 (and only one) guy who
> > was functionally illiterate. Reasonably smart, but the poor guy
> > could not read.
> >
> > How does this contrast with Russian conscripts who may be drawn
> > from a wide range of native languages?
> >
> > Pete
>
> Russia: 99.6%
> US: 97%
>
> http://www.cia.gov/cia/publications/factbook/geos/rs.html#People
> http://www.cia.gov/cia/publications/factbook/geos/us.html#People
>

I wouldn't call 2% "much better". But the question still remains.

The CIA Factbook defines it as "age 15 and over can read and write "
I understand Russians are/were to be educated in the 'official language'.
But is that really true? An otherwise highly intelligent, literate conscript
mechanic, who was not educated in the Mother tongue, would still not be able
to reliably maintain a modern tank or aircraft.

If I were plunked down in the Finnish, Brazilian or Russian AF at age 18, I
wouldn't expect to do a very good job.

Pete