Diesel vs. Gas

[flamingknives]

Yes, gas turbines are simple. They require greater tolerances and better materials, but that doesn't make them more complex.

For a gas turbine, I need a duct, a set of fan blades, a set of turbine blades, a few bearings and a shaft to mount the blades on and take the power off.

For a V12, I need a cylinder block, a cylinder head, a set of cylinders, a set of connecting rods, 2 to 4 valves in each cylinder, a set of spark plugs, power to the same, carburetor(s), an oil system, a timing mechanism, a shaft to take the power off and two camshafts.

Piston engines don't like sand either.

If the M1s needed maintenance every 3 hours, then I would hazard that this is a problem with the sand filter (this was found to be a problem to the Challenger 2s used in exercise Saif Saera (sp?)) You can't replace a set of turbine blades that often and remain effective.

But yes, they are thirsty and expensive in terms of manufacture due to demanding operating environment, not complexity.

[Incoming9000]

I belive the problem in this issue resides in the definition of simple and complex.

What is simple? How to define it? In this case is it the number of parts? The the tecnical expertise necessary to manufacture the engines? The maintenance? Ease of use? All of them put together?

Let's get some points straight first.

I belive we both agree that Gas turbanies are:

Expensive to manufacture and maintain, thirsty (fuelwise) and have a better weight to power ratio.

They do have less independently moving parts than an Diesel engine but because of their low tolerance to failure than Diesel their need fir more care and maintenace and demanding air filters to suply the extreme need for air means that overal they are more dificult to maintain at optimal capacity needed for combat situations. This is what I define as complex.

Yes Diesel don't like sand either, but are far more forgiving and can run under very adverse contitions longer without any special care. This is what i define as simplicity.

About the filter problems: That's the result of the extreme need for air that turbines have. There's nothing wrong with the filters. In a sandy environment the filters simply endup needing cleaning much more often.

[Gadzilla]

Your big maintaince savings with a gas turbine is that you dont really do much to it in the field, other than the usuall preventitive stuff. When there is a problem you just pull the entire engine out, which is not a big deal because of its lightness, and pop another one in. The bad engine gets packed into a big can and shipped to a rework facillity in the rear. I have some experience with this I was a USMC helo Crewchief.

[Guest Mike]

Sand in a turbine will do almost nothing to a gas turbine engine - they are EXTREMELY tolerant of minor damage to all the major rotating parts and the combustion cans.

what happens with sand and other abrasives is it slowly wears teh profile of the compressor and turbine, and causes a gradual loss of power - by gradual I'm talking over hundreds of hours of operation. This wil usually be noticed and a erplacement engine scheduled at a convenient time before it gets to be critical.

Aircraft Gas turbine blades are routinely blasted with low-abrasive materials such as cork and walnut shell to remove deposites of salt and other undesireables that do the reverse - they build up on blades - especially compresor ones, and reduce the efficiency of the engine.

Gas turbines can usually take small fod (foreign object damage) without much bother too - nuts, bolts, chickens, people - most of them only cause a blip. Aircraft engines are removed after such incidents only if there's some indication of internal damage that needs further investigation such as increased vibration.

What kills all engines is sand in the bearings - doesn't matter what sort of engine you have if it's got sand there then it's dead in short order.

All engines require sand filters in the desert - remember the changes made to the profile of het Spitfire for desert service in WW2 with a big sand filter under the engine cowling?

"Constant maintenance" is probably the maintenance of the filter, not the engine.

Gas turbines also do not actually burn more fuel than reciprocating engines do - but they do tend to be run for longer because it is inefficient to start and stop them often. The life of a turbine is greatly affected by the number of stop/start cycles and it's best if they're minimised. As a result a GT engine may well be left running when a reciprocating engine would be turned off.

Modern mixed-cycle powerplants such as the Capstone system use GT engines running at constant speeds in perference to anything else because they're so much mroe efficient.

[ March 04, 2003, 07:44 PM: Message edited by: Mike ]

[felixgrey]

I thought JP-8 was a diesel product. (At least that is what I was lead to believe in the army)

In my M1A1 I could blow through the 550 Gal fuel tanks in a day or less depending on what we were doing.

As for desert sand - the problem we had in Kuwait was that our air filters became clogged with the fine particles of sand. We had to stop ever three hours to hook up a hose to the engine and blow the sand out of out filters. The newer tanks (M1A2s) have automatic sand filter blowers. The engine can blow out the filters with out needing to stop. However a good crew will manually blow out the filters after a day of manuver.

Hope this helps.

Scott

[ March 05, 2003, 08:15 AM: Message edited by: felixgrey ]

[flamingknives]

I belive the problem in this issue resides in the definition of simple and complex

You're not wrong there. As an engineer, I use number of moving parts for complexity.

Unreliable or sensitive would apply to maintenance.

They do have less independently moving parts than an Diesel engine but because of their low tolerance to failure than Diesel

Where do you get this idea from?

Aeroplanes do not regularly drop out of the sky because of foreign particles getting into their engines (you'll note that there is no kind of filter on any jet aircraft) try chucking a handful of sand down the air intake of a diesel and see how it likes it.

[Ant]

you'll note that there is no kind of filter on any jet aircraft

You cannot put a filter on a jet aircraft as it would impede the airflow through the intake. It's not a question of not needing one, you just can't do it.

[ March 05, 2003, 10:33 AM: Message edited by: Ant ]

[SgtMuhammed]

Well you could but you would have to have an intake that was gigantic in order to get enough air flow. That is why aircraft engines are designed to withstand hits by normal debris such as birds. (This is also why the Air Force has invested a lot of money in chicken substitutes for testing as well as the chicken gun to fire them at test engines.)

[Ant]

Well you could but you would have to have an intake that was gigantic in order to get enough air flow

No you can't. A jet aircraft intake is far more complex than most people realise. It's not just a case of funnelling enough air into the engine. It needs to produce a correct shockwave (or several for military a/c) in order to slow the air enough so that the engine can handle it. A gas turbine engine cannot handle an airflow that is as fast as modern jet aircraft can fly.

[Sailor Malan]

Originally posted by Ant:

</font><blockquote>quote:</font><hr />you'll note that there is no kind of filter on any jet aircraft

You cannot put a filter on a jet aircraft as it would impede the airflow through the intake. It's not a question of not needing one, you just can't do it. </font>

[Incoming9000]

Concerning the robustness of Jet turbines I would like to say just this:

This is what happened to a Boeing 737 Turbine after sucking in a 3Kg bird.

[offtaskagain]

Wow that's quite a bit of damage. That isn't normal in a bird strike. My dad was a jet engine mechanic in the Air Force and would ocasionally take me into his shop. One time he showed me an engine from an A-10 that had taken a goose through it. He said it didn't really have any damage but was taken out to verify that. The only way you could even tell a bird had gone through was some black crud fried to some of the turbine blades. So no real damage from that bird strike.

[SgtMuhammed]

Then again that is because the A10 tends to take bird strikes from the rear.

Yes you can put filters on jet engines. If you wanted to have huge intakes to provide needed airflow then designing the ducts to provide the proper shockwave is the least of your worries. Civilian aircraft don't even need the ducting because of the different characteristics of their engines. While filters would be impractical in the extreem they are by no means impossible.

[Stalin's Organ]

Turboprop engines often have a vertical bend to teh intake that serves as a filter - eg the PW100 series engines on the DHC-8 have this, and a small door to allow heavy debris carried by hte airflow to continue in a straight line and avoid hte engine - although this is primarily for ice protection.

Quite frankly I do not believe the picture above is from a single bird strike - I used to work in a JT8D (727 and old style 737 engines) overhaul shop and saw lots of impact damage including multiple bird strikes and none of them came close to being that much damage - they also didn't stop the engine actually working.

[Gyrene]

Originally posted by Stalin's Organ:

Turboprop engines often have a vertical bend to teh intake that serves as a filter - eg the PW100 series engines on the DHC-8 have this, and a small door to allow heavy debris carried by hte airflow to continue in a straight line and avoid hte engine - although this is primarily for ice protection.

Quite frankly I do not believe the picture above is from a single bird strike - I used to work in a JT8D (727 and old style 737 engines) overhaul shop and saw lots of impact damage including multiple bird strikes and none of them came close to being that much damage - they also didn't stop the engine actually working.

I have to agree with Stalin's Organ - I did overhaul work on CF-6's & TF-39's with General Electric (747's, 757's, , CF5's, Air Force One...) and I've seen quite a bit of FOD damage and I can tell you that no 3kg bird would FOD a turbofan like that unless it was the Bird of Steel™

I've seen the chicken gun & frozen turkey tests and that's more than 3kg and a lot harder.

Mike: I think you are mistaken in thinking that sand is not a threat to blade life in turbines - During the Gulf War we lost a few helicopters to compressor stalls caused by sand erosion, including one in my squadron that took a 50 foot plunge during a hover check.

Our GE rep later sent us some compressor blades to show us just how much damage the fine Saudi sand did in such a short time, some of them looked like scimitars! Turns out that the T64's in CH53's were the most erosion prone of all helicopter engines in the theater, probably because they're also the only pure axial flow turboshafts used in allied helicopters.

Sand also played havoc with fuel control linkage.

Gyrene

[Incoming9000]

The information I have about the picture is that it was taken from a 737 engine that sucked it a 3 Kg bird during takeoff. The Bird itself only made minor damage, but because of the full throttle needed for takeoff, making the engine work at maximum power, any damage, as slight it might be would cause slpinters from the blades, or anything else, to wreck havok inside the high pressure engine. It's the domino efect. The slightest damage can initiate a chain reacton that causes tremendous efects.

Here are some examples I found:

(There were more but I picked these as examples of how one bird can damage an engine. For the hole page go here.)

Date: 03 June 1995

Aircraft: Concorde

Airport: John F. Kennedy (NY)

Phase of Flight: Landing roll

Effect on Flight: Aircraft was towed to gate

Damage: Engines

Wildlife Species: Canada geese

Comments from Report: Aircraft ingested a Canada goose into the #3 engine which had an uncontained failure causing parts to go into the #4 engine. Both engines were destroyed. Flames and smoke were seen coming from both engines. Cost was over $9 million. Aircraft was out of service for 5 days. The NY Port Authority paid $5.3 million in compensation for losses.

Date: 2 June 1996

Aircraft: B-737

Airport: Chicago Midway (IL)

Phase of Flight: Climb (100’ AGL)

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Gull

Comments from Report: Ingested a gull during climb out. Tower observed flames from #2 engine and advised pilot who declared an emergency and returned to land without incident. Emergency equipment was on the runway. Aircraft landed using single engine landing procedures. Core and all fan blades were damaged. Engine was rebuilt.

Date: 27 January 1997

Aircraft: DC-10

Airport: Los Angeles Intl. (CA)

Phase of Flight: Climb

Effect on Flight: Engine shut down

Damage: Engine

Wildlife Species: Gull

Comments from Report: Crew thinks they hit a gull shortly after take off. #3 engine had a vibration with oil quantity fluctuation. When oil quantity dropped to zero, ¾ of the way to Japan, the engine was shut down. Crew had planned to divert to Anchorage but decided against it due to poor weather. Feathers found in engine after landing. Cost $1.5 million.

Date: 15 November 1997

Aircraft: Airbus 320

Airport: John Wayne (CA)

Phase of Flight: Take off

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Large bird

Comments from Report: A large bird was ingested into one of the two engines causing a fire. Passengers heard a loud boom, then the aircraft dropped momentarily before recovering altitude. The aircraft circled for 30 minutes before making an emergency landing. There were no injuries. Bird hit blades on starboard fan which broke or bent all blades causing damage to cowling and to system behind the fan. Engine changed. Time out of service 30+ hrs. Cost of repairs $300,000 and other cost $800,000.

Date: 23 August 2000

Aircraft: B-747

Airport: Philadelphia Intl. (PA)

Phase of Flight: Take off

Effect on Flight: Aborted take off

Damage: Engine, wing

Wildlife Species: Canada geese

Comments from Report: The aircraft flew through a flock of about 30 Canada geese and ingested 1 or 2 in the #1 engine. The high-speed aborted take off resulted in 9 flat tires. The aircraft was towed to the ramp. Time out of service was 72 hours. Engine was a total loss. Cost was $3 million.

Date: 21 January 2001

Aircraft: MD-11

Airport: Portland Intl. (OR)

Phase of Flight: Take off

Effect on Flight: Aborted take-off, engine shut down

Damage: Engine

Wildlife Species: Herring gull

Comments from Report: The #3 engine ingested a Herring gull. The engine stall blew of the nose cowl that was sucked back into the engine and shredded. The engine had an uncontained failure. The pilot aborted take-off and blew two tires. 217 passengers were safely deplaned and rerouted to other flights.

Date: 09 June 2001

Aircraft: Airbus 300

Airport: Dayton Intl. (OH)

Phase of Flight: Climb (200’ AGL)

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Canada goose

Comments from Report: A Canada goose was ingested into the #2 engine shortly after lift off. The engine had an uncontained failure and a precautionary landing was made. The cost to repair ($3.5 million) was not economical so the engine was scrapped

Date: 06 December 2001

Aircraft: B-737

Airport: Detroit Metropolitan (MI)

Phase of Flight: Climb

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Gulls

Comments from Report: Aircraft struck a flock of gulls, ingesting one after take off. Engine rolled back, and then started compressor stalls. Pilot pulled throttle back to idle and returned to airport. Emergency landing make due to engine flame out. The engine was replaced. Cost estimated at $2.3 million.

Date: 24 February 2002

Aircraft: Fk-100

Airport: Dallas-Fort Worth (TX)

Phase of Flight: Climb (6000’ AGL)

Effect on Flight: Precautionary landing

Damage: Engine, nose, wing

Wildlife Species: Greater white-fronted goose

Comments from Report: Aircraft struck a flock of geese and ingested one after takeoff. Engine vibration caused crew to reduce power to idle. Nose was damaged. Several blades were deformed. Engine was replaced. Bird ID by Smithsonian. Cost of repairs and lost revenue totaled $654,000. Aircraft was out of service for 8 days.

[ March 06, 2003, 07:06 AM: Message edited by: Incoming9000 ]

[Ant]

Originally posted by sGTGoody:

Yes you can put filters on jet engines. If you wanted to have huge intakes to provide needed airflow then designing the ducts to provide the proper shockwave is the least of your worries. Civilian aircraft don't even need the ducting because of the different characteristics of their engines. While filters would be impractical in the extreem they are by no means impossible.

Sorry, confusion of terms. I'm aware that you can put filters on jet ENGINES. As previosly mentioned about helicopters, and no doubt Abrams tanks. My point was that I was under the impression you couldn't put them on jet AIRCRAFT that fly at 600mph. I was trying to make the point (rather badly unfortunately ) that the reason jet AIRCRAFT don't have filters is not because the engines don't need them but because they are totally impractical.

[flamingknives]

Jet aircraft do not need filters. If they did, then a supersonic aircraft would be impossible, rather than the other way around.

[Ant]

Originally posted by flamingknives:

Jet aircraft do not need filters. If they did, then a supersonic aircraft would be impossible, rather than the other way around.

You could argue that the previous photo of the 737 engine rather demonstrates that they do. It's just that their need for filters is far far outweighed by the impracticalities of actually having them

[MikeyD]

I doubt an M1A1 worrys much about sucking birds into the engine .

But the turbine has other problems that some would say counterbalance the benefits. First is the heat given off. Gone are the days of G.I.s hitching a ride on the engine deck of their support tank. Perched on the turret maybe, but not on the engine deck. Also. the U.S. has been lucky (careful) not to start wars with anyone who's too technologically sophisticated. The IR signature of the hot M1 would be a great aiming point from above.

There's also the gas hog problem. M1 mileage is measured gallons per mile, not miles per gallon, and the logistics chain to keep 'em fueled in the field is something to behold. I recall the M1A1 had to install a small add-on petrol engine just to run the electric with the turbine off because a turbine uses just about as much fuel idling at a checkpoint as running full-out! A modern 1500 hp diesel gets twice(?) the gas mileage of a 1500 turbine. That means half as many fuel bowsers tagging behind.

[ March 06, 2003, 10:12 AM: Message edited by: MikeyD ]

[Sailor Malan]

Originally posted by Incoming9000:

The information I have about the picture is that it was taken from a 737 engine that sucked it a 3 Kg bird during takeoff. The Bird itself only made minor damage, but because of the full throttle needed for takeoff, making the engine work at maximum power, any damage, as slight it might be would cause slpinters from the blades, or anything else, to wreck havok inside the high pressure engine. It's the domino efect. The slightest damage can initiate a chain reacton that causes tremendous efects.

Here are some examples I found:

(There were more but I picked these as examples of how one bird can damage an engine. For the hole page go here.)

Date: 03 June 1995

Aircraft: Concorde

Airport: John F. Kennedy (NY)

Phase of Flight: Landing roll

Effect on Flight: Aircraft was towed to gate

Damage: Engines

Wildlife Species: Canada geese

Comments from Report: Aircraft ingested a Canada goose into the #3 engine which had an uncontained failure causing parts to go into the #4 engine. Both engines were destroyed. Flames and smoke were seen coming from both engines. Cost was over $9 million. Aircraft was out of service for 5 days. The NY Port Authority paid $5.3 million in compensation for losses.

Date: 2 June 1996

Aircraft: B-737

Airport: Chicago Midway (IL)

Phase of Flight: Climb (100’ AGL)

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Gull

Comments from Report: Ingested a gull during climb out. Tower observed flames from #2 engine and advised pilot who declared an emergency and returned to land without incident. Emergency equipment was on the runway. Aircraft landed using single engine landing procedures. Core and all fan blades were damaged. Engine was rebuilt.

Date: 27 January 1997

Aircraft: DC-10

Airport: Los Angeles Intl. (CA)

Phase of Flight: Climb

Effect on Flight: Engine shut down

Damage: Engine

Wildlife Species: Gull

Comments from Report: Crew thinks they hit a gull shortly after take off. #3 engine had a vibration with oil quantity fluctuation. When oil quantity dropped to zero, ¾ of the way to Japan, the engine was shut down. Crew had planned to divert to Anchorage but decided against it due to poor weather. Feathers found in engine after landing. Cost $1.5 million.

Date: 15 November 1997

Aircraft: Airbus 320

Airport: John Wayne (CA)

Phase of Flight: Take off

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Large bird

Comments from Report: A large bird was ingested into one of the two engines causing a fire. Passengers heard a loud boom, then the aircraft dropped momentarily before recovering altitude. The aircraft circled for 30 minutes before making an emergency landing. There were no injuries. Bird hit blades on starboard fan which broke or bent all blades causing damage to cowling and to system behind the fan. Engine changed. Time out of service 30+ hrs. Cost of repairs $300,000 and other cost $800,000.

Date: 23 August 2000

Aircraft: B-747

Airport: Philadelphia Intl. (PA)

Phase of Flight: Take off

Effect on Flight: Aborted take off

Damage: Engine, wing

Wildlife Species: Canada geese

Comments from Report: The aircraft flew through a flock of about 30 Canada geese and ingested 1 or 2 in the #1 engine. The high-speed aborted take off resulted in 9 flat tires. The aircraft was towed to the ramp. Time out of service was 72 hours. Engine was a total loss. Cost was $3 million.

Date: 21 January 2001

Aircraft: MD-11

Airport: Portland Intl. (OR)

Phase of Flight: Take off

Effect on Flight: Aborted take-off, engine shut down

Damage: Engine

Wildlife Species: Herring gull

Comments from Report: The #3 engine ingested a Herring gull. The engine stall blew of the nose cowl that was sucked back into the engine and shredded. The engine had an uncontained failure. The pilot aborted take-off and blew two tires. 217 passengers were safely deplaned and rerouted to other flights.

Date: 09 June 2001

Aircraft: Airbus 300

Airport: Dayton Intl. (OH)

Phase of Flight: Climb (200’ AGL)

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Canada goose

Comments from Report: A Canada goose was ingested into the #2 engine shortly after lift off. The engine had an uncontained failure and a precautionary landing was made. The cost to repair ($3.5 million) was not economical so the engine was scrapped

Date: 06 December 2001

Aircraft: B-737

Airport: Detroit Metropolitan (MI)

Phase of Flight: Climb

Effect on Flight: Precautionary landing

Damage: Engine

Wildlife Species: Gulls

Comments from Report: Aircraft struck a flock of gulls, ingesting one after take off. Engine rolled back, and then started compressor stalls. Pilot pulled throttle back to idle and returned to airport. Emergency landing make due to engine flame out. The engine was replaced. Cost estimated at $2.3 million.

Date: 24 February 2002

Aircraft: Fk-100

Airport: Dallas-Fort Worth (TX)

Phase of Flight: Climb (6000’ AGL)

Effect on Flight: Precautionary landing

Damage: Engine, nose, wing

Wildlife Species: Greater white-fronted goose

Comments from Report: Aircraft struck a flock of geese and ingested one after takeoff. Engine vibration caused crew to reduce power to idle. Nose was damaged. Several blades were deformed. Engine was replaced. Bird ID by Smithsonian. Cost of repairs and lost revenue totaled $654,000. Aircraft was out of service for 8 days.

Bird strikes are a serious hazard for all aircraft. The cases you quote (and more) are plenty of evidence of that. Consider that at take off a modern airliner is doing say 150mph (and this is LOW). A 3kg bird is on the big side, but not outrageous (the latest proposed rules demand 'run-on' after a 5.5lb bird). Thats quite a blow (work out the kinetic energy). I have more experience of military aircraft, but a direct hit on a wing leading edge, or the cockpit canopy will often do more damage that the same hit on the engine (there are lots of variables involved).

For every case cited on a birdstrike database there will be many that go unnoticed until maintenance checks on the ground.

However, bird damage doesn't really relate to the relative robustness as a tank engine.

GT are vulnerable to sand, but, so are reciprocating engines. I do not know the relative rates, but you can certainly write off a diesel if you run without filters.

The debate is really one of power density and fuel burn.

[c3k]

I'll chime in on this:

The reason the M1 Gas Turbine engine is a gas hog is, as referenced, because of its OVERRALL high fuel consumption. I would submit that the amount of fuel used per horsepower produced at PEAK production would compare quite favorably with diesels (modern, but especially with engines available in the early '80's).

Any recipricoting engine will generally produce more power at higher rpms (I said GENERALLY!!), and they will consume more fuel with higher rpm. Hence, when no power is needed (the tank is still), the engine idles (producing little power), and consuming a minimum amount of fuel.

Not so for the M1's turbine. Turbines have a lot of good points. However, this one was designed for a peak power production. Because of this there were design tradeoffs. (Anyone wanting to discuss iterative design cycles with turbines are welcome to join in.) One of the tradeoffs was that it was optimized for a narrow rpm band. Hence, at an rpm off that optimized design point, the fuel usage skyrockets for the horsepower produced.

Yes, the latest M1's are designed to have an auxiliary power unit - a diesel generator.

Ken

[SgtMuhammed]

Moving away from the technical, some other advantages of the M1's turbine is that it doesn't sound like a tank. Interestingly you can get a sound contact on an M1 when it is further away. Within a couple hundred meters all you hear is a whine and the track squeaking. They also smell a lot better than an M60. Crank up a company of 60s and it is hard to breath. M1s, on the other hand, smell like someone is cooking something (although I have never been able to decide exactly what). They also make great clothes dryers for any attached infantry. Just stand in the jet blast and you are dry in a matter of seconds.

[Incoming9000]

Originally posted by sGTGoody:

(...) They also smell a lot better than an M60. Crank up a company of 60s and it is hard to breath. M1s, on the other hand, smell like someone is cooking something (although I have never been able to decide exactly what) (...)

"Eeeh... what's cooking doc?"

PS: Sorry couldn't help myself!

PSPS: Has anyone thought of smell detectors?

South of Iraq (0100 Hours)

Iraqui Soldier: (Snif, snif) Sir We have M1s 5 Km to the south.

Iraqui Officer: (Snif, snif) No, too much oil. They're M60s.

Iraqui Soldier: But sir I smelled Chicken!

Iraqui Officer: (Snif,Snif) No it's smells like Beef, but you're right! There's something cooking! Those sneaky American pigs tried to fool us by puting M60s in front of M1s!

[ March 06, 2003, 05:36 PM: Message edited by: Incoming9000 ]

[Guest Mike]

Originally posted by Incoming9000:

The information I have about the picture is that it was taken from a 737 engine that sucked it a 3 Kg bird during takeoff. The Bird itself only made minor damage, but because of the full throttle needed for takeoff, making the engine work at maximum power, any damage, as slight it might be would cause slpinters from the blades, or anything else, to wreck havok inside the high pressure engine. It's the domino efect. The slightest damage can initiate a chain reacton that causes tremendous efects.

True - but hte photo was of teh front blades - the 1st stage compressor, and GT engines that suffer catastrophic failures do not generlaly propogate damage forwards, so I'd expect all that damage to have come from eth impact.

Clearly something caused it, but I'm sceptical about a single bird being the cause.