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  # 2357385 19-Nov-2019 18:41
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tripper1000:

 

Fred99:

 

...IIRC the maximum short term (takeoff) thrust rating of each of twin engines has to exceed what's required per engine in 3/4 engine planes, so in normal operation there's more in reserve. (IOW they're running at lower % of maximum - less stressed) There's also an offsetting factor, all other things being equal you're twice as likely to have uncontained engine failure with 4 engines.....

 

That was kind of the problem first time round with the RR's - they are fine when under-stressed in cruise but they wouldn't last long enough on one engine at wide open throttle.

 

I'm not so sure I agree with where your unconstrained engine theory is heading. There is no question that 4 engines is better for your survival than 2. ETOPS 240 is a very good reating for a twin jet (ETOPS 180 is more common) and is hard work for an airline to maintain, but the standard B474-8 is rated at ETOPS 330 straight out of the factory, so the regulators are far more confident the 747's ability to get you there after an engine failure (or 2 ๐Ÿ˜ƒ) than a twin jet. 

 

 

I don't know how a 747 could be ETOPs certified - it stands for Extended-range Twin-engine Operational Performance Standards, so there's no such thing for a 4 engine plane. 

 

Yes all things being equal, then 4 engines should probably be safer than 2, but there's only a few 747s left, the A380s are aging and not going to be replaced, and I expect that modern twin engine planes record is probably *much* better with more modern engines than when the 747 ruled the skies.  With an exception, Queen President Ivanka's new AF1 planes will have new generation engines, and under his eye, she'll be safe as.


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  # 2357388 19-Nov-2019 18:47
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mattwnz:

 

PolicyGuy:

 

noroad:
Anyone going to Mars who it relying on making the return trip is fooling themselves, and lets be real, its unlikely to happen in our lifetimes anyway.

 

mattwnz:
... But i think anyone initially going, it is likely to be a one way trip, as so many things can go wrong.

 

 

 

I thought that part of the 'deal' was that the initial trips will be one way.
This is in the same sense that the first Irish, Scottish and English settlers to Australia - mostly not volunteers, admittedly - were on a one-way trip. It wasn't a kamikaze-style suicide trip or a death sentence, but the cost and likelihood of ever going 'home' are such a high barrier that most of the people going out never expected to go back, and indeed very few did.

 

 

 

 

I think people who initially went to the moon probably expected that they may not return either. That is also using 50 year old technology and a lack of knowledge of space, where things should have improved significantly. 

 

 

Was a bloody miracle that they all got home IMO.  They were also the furthest from earth and still are by a long shot, nobody since even close, and the only humans to travel outside the magnetosphere.


 
 
 
 


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  # 2357394 19-Nov-2019 19:09
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noroad:

 

 P3 Orion we would shut down one of the three engines as a matter of course during patrols to save fuel, sometimes even just flying on two to really extend time on station.

 

 

Funny coincidence,  had a retired Orion pilot for dinner here night before last, and he told me that they'd actually shut down three engines at times when on ocean patrol. You possibly know him, and I'm not saying any more, there's a chance he might have been breaking some rules.


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  # 2357425 19-Nov-2019 19:27
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Linux:

 

@Batman Title should be useless Rolls Royce Engines not Boeing, The Airlines pick what engines go on the plane when they buy them

 

AirNZ picked the RR for the DreamLiner

 

 

Aren't the moving to GE now?


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  # 2357436 19-Nov-2019 20:15
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Fred99:

 

I don't know how a 747 could be ETOPs certified - it stands for Extended-range Twin-engine Operational Performance Standards, so there's no such thing for a 4 engine plane. 

 

 

 

 

I can see how you say that but actually a 747 can be certified for ETOPS. Even though ETOPS was originally a Twin Engine certification it has been to extended to 3 and 4 engined aircraft. Originally the term LROPS was used for aircraft with more than two engines but ETOPs has become the standard terminology.

 

It should also be pointed out that ETOPs doesn't just relate to engine out scenarios. One other consideration is fire suppression in the cargo hold and the ability to suppress a fire for a required amount of time.





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  # 2357438 19-Nov-2019 20:17
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Fred99:

 

Was a bloody miracle that they all got home IMO.  They were also the furthest from earth and still are by a long shot, nobody since even close, and the only humans to travel outside the magnetosphere.

 

 

 

 

Yes it was a miracle. If you saw "The First Man" it was pretty obvious they weren't confident they'd see their families again.





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  # 2357450 19-Nov-2019 20:32
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Fred99:

 

I don't know how a 747 could be ETOPs certified - it stands for Extended-range Twin-engine Operational Performance Standards, so there's no such thing for a 4 engine plane. 

 

That's the official meaning of that acronym

 

But it really stands for
   Engines
   Turning
   Or
   Passengers
   Swimming

 

๐Ÿ˜‰


 
 
 
 


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  # 2357488 19-Nov-2019 21:12
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Technically ETOPS isn't really used now anyway. ETDO is the new ICAO term.

 

 

 

 


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  # 2357491 19-Nov-2019 21:22
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Fred99:

 

 

 

 

 

 

 

Was a bloody miracle that they all got home IMO.  They were also the furthest from earth and still are by a long shot, nobody since even close, and the only humans to travel outside the magnetosphere.

 

It was amazing to see some of the coverage for the 50th anniversary, and how primitive some of the things were back then. Especially the electronics, and 'computers'. The only thing that I have seen that has impressed me more recently is those self landing Space X rockets . I wouldn't be surprised if China send people to mars before anyone else.


neb

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  # 2357561 20-Nov-2019 00:18
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noroad:

Fred99:

 

Meanwhile, Musk's going to be taking to people to Mars and back with one main engine, and if that engine so much as farts for a couple of seconds at a critical time, you're either going to crash on a planet or miss your destination completely, spending the last of your days lost in space waiting to run out of food/air/water.

 

 

 

 

Anyone going to Mars who it relying on making the return trip is fooling themselves, and lets be real, its unlikely to happen in our lifetimes anyway.

 

 

Would someone want to mention to Trump that he'd be absolutely the greatest person ever if he was the first to Mars? In that case I'm sure at least one trip would occur as quickly as the crowdfunding would allow.

neb

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  # 2357562 20-Nov-2019 00:20
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mattwnz:

I expect it would have to land in a similar way too the lunar landers. Although it would probably need to be a combination with a parachute to initially slow it down enough. I don't think it is a huge issue. But i think anyone initially going, it is likely to be a one way trip, as so many things can go wrong. 

 

 

It's probably the single biggest issue with Mars. It has too much atmosphere to use retro-rockets, but too little atmosphere to use it to help the landing. There's no easy way to land there, which is why we've seen such... novel approaches in the past.

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  # 2357636 20-Nov-2019 08:53
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Don't fly, and save our atmosphere. Problem solved!





:)




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  # 2357730 20-Nov-2019 11:31
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there isn't any Asian or Russian 4rd party service centers that could give ad hoc maintenance? this should be a business opportunity for some clever clogg! 





Involuntary autocorrect in operation on mobile device. Apologies in advance.


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  # 2358129 20-Nov-2019 17:53
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Batman:

 

there isn't any Asian or Russian 4rd party service centers that could give ad hoc maintenance? this should be a business opportunity for some clever clogg! 

 

 

Not likely to happen, ever. They would need approval from Roll Royce and the various National Aviation Authorities. Getting regulatory sign off from the NAA's MAY be doable buy I very much doubt Roll Royce would hand out their approval to just anyone.

 

This sort of work is highly specialised requiring manufacturer provided training for the employees and very often requiring special tooling and unique stands and mounts to hold the engines and components while they are being worked on. Then there'd need to be a suitable test cell to run the engines in. This all costs money. There's very good economic reasons why there are very few service centres.

 

There aren't enough engines in service to justify a multitude of service centres. This reliability "blip' has put significant short term pressure on the existing facilities.





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  # 2358185 20-Nov-2019 20:06
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Technofreak:

 

There aren't enough engines in service to justify a multitude of service centres. This reliability "blip' has put significant short term pressure on the existing facilities.

 

 

They're somewhat going down that path.

 

These include the announcement today that part of our existing sites in Dahlewitz and Montreal will transition to become service hubs with the capability of handling Trent 1000 engine overhauls. We have secured the use of an additional test bed at Dallas Fort Worth to support Trent 1000 engine tests. Additionally, we are investing to expand our capacity in Derby and double our overhaul capacity at Heathrow.

 

..

 

This effort will be aided by a bespoke facility we have created in Derby dedicated to Trent 1000 test engines, which is now fully operational


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