comparing russian and US jet engines OH times

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

"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.

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

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.

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.

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

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 MainBoxatjrwlynch[dot]demon{dot}co(.)uk

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.

) 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 MainBoxatjrwlynch[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.

(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.