Multi engined Airliners
Multi engined Airliners
I just happened to come across the Airliners.net site & saw a thread discussing the merits good or bad about having 4 eng planes still being built.
So thought why not have a 'chat' about it here where it can get interesting & amusing
Okay basic stuff. 4 engines good for ETOPS/EDOPS/EROPS etc, smaller size per engine for better installation slung under wing/s. Better redundancies etc.
The 3 Eng concept seems to have died off
Let the games begin.
Wmk2
So thought why not have a 'chat' about it here where it can get interesting & amusing
Okay basic stuff. 4 engines good for ETOPS/EDOPS/EROPS etc, smaller size per engine for better installation slung under wing/s. Better redundancies etc.
The 3 Eng concept seems to have died off
Let the games begin.
Wmk2
Last edited by Wally Mk2; 11th Aug 2013 at 02:09.
4 engines also better for 2nd segment performance (3/4 of power left after a failure, instead of only 1/2), so can be smaller.
Problem is whether 4 smaller donks cost the same or less than 2 bigger ones, relatively more powerful ones. I very much doubt it.
Problem is whether 4 smaller donks cost the same or less than 2 bigger ones, relatively more powerful ones. I very much doubt it.
That's true 'bloggsy' everything is predicated on the 2nd segment (the worst case) but it's interesting to watch the A380 takeoff at heavy weights they seem to stagger into the air & climb the same as a C150 on a hot day! Optical illusion obviously but I'd hate to see one of the ugly beasts lose a donk out of Melb on a 40 deg day...eeeekkk!
I guess it comes down to just how 'safe' are 2 eng's compared to 4 (or 3 for Eg)
'Safe' is subjective, safest is to stay in bed & never get up!:-)
Wmk2
I guess it comes down to just how 'safe' are 2 eng's compared to 4 (or 3 for Eg)
'Safe' is subjective, safest is to stay in bed & never get up!:-)
Wmk2
Wally et al,
Let's drop the word "safe" and use the word "risk", safe is an emotive word without definition, risk can be measured.
Going right back to the early days of EROPS/ETOPS now EDTO, have we all forgotten that the original risk analysis showed that in-flight fire was a greater risk than engine failure, hence the significantly different hold certification standards now applied.
The risk of an engine failure, when an aircraft is in cruise and in the EDTO phase of flight is, as I think we all know, very low, almost vanishingly low. It has been clearly demonstrated in practice, not just theory.
I would have thought that the last 30+ years of long range twin operation had put the question beyond argument.
(1) Right now, how many 4 engine large civil aircraft are in production?
(2) In each case, how are their sales going, what is the order backlog?
(3) How many of the above were delivered last year and how many deliveries have been deferred?
(4) Will the A380 production ever reach break even levels, let alone make a profit?
(5) Will Boeing ever make a buck out of the B747-8?
(6) How many EDTO certified or certifiable twins were delivered last year, and how many are on order?
The answers to the numbers questions, of course, is tens versus thousands --- I would say the market has spoken, wouldn't you.
Much of the Qantas long haul commercial malaise right now is attributable to not having ordered B777 almost 20 years ago, because the company was not, in my opinion, being run in the best interests of the shareholder and the company.
If Qantas has had fuel competitive aircraft for the last 10-15 years, instead of increasingly tired B744, the bottom line would be very different right now.
Tootle pip!!
Let's drop the word "safe" and use the word "risk", safe is an emotive word without definition, risk can be measured.
Going right back to the early days of EROPS/ETOPS now EDTO, have we all forgotten that the original risk analysis showed that in-flight fire was a greater risk than engine failure, hence the significantly different hold certification standards now applied.
The risk of an engine failure, when an aircraft is in cruise and in the EDTO phase of flight is, as I think we all know, very low, almost vanishingly low. It has been clearly demonstrated in practice, not just theory.
I would have thought that the last 30+ years of long range twin operation had put the question beyond argument.
(1) Right now, how many 4 engine large civil aircraft are in production?
(2) In each case, how are their sales going, what is the order backlog?
(3) How many of the above were delivered last year and how many deliveries have been deferred?
(4) Will the A380 production ever reach break even levels, let alone make a profit?
(5) Will Boeing ever make a buck out of the B747-8?
(6) How many EDTO certified or certifiable twins were delivered last year, and how many are on order?
The answers to the numbers questions, of course, is tens versus thousands --- I would say the market has spoken, wouldn't you.
Much of the Qantas long haul commercial malaise right now is attributable to not having ordered B777 almost 20 years ago, because the company was not, in my opinion, being run in the best interests of the shareholder and the company.
If Qantas has had fuel competitive aircraft for the last 10-15 years, instead of increasingly tired B744, the bottom line would be very different right now.
Tootle pip!!
Last edited by LeadSled; 11th Aug 2013 at 02:55.
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You are assuming of course, leadsled, that the reduction in fuel costs would have stayed in the company's coffers instead of ending up in bank accounts of managers, consultants, lawyers and politicians.
Pro’s Twins
We run twice daily flights from Asia to SFO. One is with a B777-300ER the other with a B747-400. Over a four day period the B777-300ER burnt 26.7% less fuel than the B747-400 for almost the same payload. Add in the significantly lower maintenance costs of the Tripler the 74 isn’t even in the race.
Con’s Twins
We operate a daily flight from Asia to JNB which has an elevation of about 5500ft. While the B777-300ER isn’t currently being used on this sector, when it is, it’s generally only used during the southern hemisphere winter as the OEI second segment is too restrictive to make it consistently viable without a tech stop in say BKK. As an example, on a 30°C day there is about a 50 Tonne payload restriction without a tech stop.
We run twice daily flights from Asia to SFO. One is with a B777-300ER the other with a B747-400. Over a four day period the B777-300ER burnt 26.7% less fuel than the B747-400 for almost the same payload. Add in the significantly lower maintenance costs of the Tripler the 74 isn’t even in the race.
Con’s Twins
We operate a daily flight from Asia to JNB which has an elevation of about 5500ft. While the B777-300ER isn’t currently being used on this sector, when it is, it’s generally only used during the southern hemisphere winter as the OEI second segment is too restrictive to make it consistently viable without a tech stop in say BKK. As an example, on a 30°C day there is about a 50 Tonne payload restriction without a tech stop.
Optical illusion obviously but I'd hate to see one of the ugly beasts lose a donk out of Melb on a 40 deg day...eeeekkk!
The 340-300- well that is a different story altogether.
Even with one engine out on a 380, your driftdown will be above the mountain goats in the Himalayas. Not as comfy on a twin across there.
Last edited by Capn Rex Havoc; 11th Aug 2013 at 04:24.
Maybe we should ask the United 777 crew who had a shutdown just past the PNR in the middle of the Pacific and then flew on one engine for over 3 hours in the middle of the night on their thoughts!
Personally for the transpacific/antarctic routes 4 engines is probably safer. 3 hour EDTO is probably pushing the limits.
Personally for the transpacific/antarctic routes 4 engines is probably safer. 3 hour EDTO is probably pushing the limits.
Last edited by neville_nobody; 11th Aug 2013 at 07:35.
Multi engined Airliners
Perhaps we could get some input from someone from CX perhaps who crew the twins and the quads? I do know they are getting more and more A330s and phasing out the A340. I don't think there is much in it as far as fuel burn goes, I gather it is about the maintenance costs of 4 vs 2 per unit?
neville_nobody
As someone who has flown both the 330 and 340, I'm more concerned about a cargo fire then an engine shutdown. One is extremely time critical, the other isn’t. To some it may sound frightening only being on one engine over the pond or arctic, but the reality is having a cargo fire in such a region is by far your worst nightmare situation, irrespective of the number of engines you have.
TwoFiftyBelowTen
I can’t give you exact figures but numbers I've heard are that the 340’s maintenance costs are about 25% higher than the 330's.
As someone who has flown both the 330 and 340, I'm more concerned about a cargo fire then an engine shutdown. One is extremely time critical, the other isn’t. To some it may sound frightening only being on one engine over the pond or arctic, but the reality is having a cargo fire in such a region is by far your worst nightmare situation, irrespective of the number of engines you have.
TwoFiftyBelowTen
I can’t give you exact figures but numbers I've heard are that the 340’s maintenance costs are about 25% higher than the 330's.
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Ozgrade3 if your talking about an engine to engine comparison I would say the 777 GE has a higher, but thats just my guess, ot sure of the figures, but surely a 747-8 wouldnt have 4 engines burning the same as a 777 GE engine? Anyway well find out in course I guess..
but the reality is having a cargo fire in such a region is by far your worst nightmare situation, irrespective of the number of engines you have.
On saying that the UPS accident in DXB puts cold shivers through any pilot.
Last edited by neville_nobody; 11th Aug 2013 at 23:42.
"Multi Engine Airliners". Aren't they all. Last non multi engine airliners I flew were Cessna !82's and 206's doing air taxi work. I fly a twin now.
Last edited by NG_Kaptain; 11th Aug 2013 at 23:55.
That isn't multi-engibne. This is multi-engine!
It was the dreaded 9 engine approach on the B36 that did my head in: (hang on, surely a B36 is just a developmental derivative of that sweet handling A36!)
http://www.nmusafvirtualtour.com/med...0Engineer.html
SB
http://www.nmusafvirtualtour.com/med...0Engineer.html
SB
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A crusty old Captain was asked his opinion on the subject:
"I like the Flight Engineer to tell me when engine #8 is running a bit hot, I then ask him which wing!"
"I like the Flight Engineer to tell me when engine #8 is running a bit hot, I then ask him which wing!"
All these useless comparisons about second segment, redundancy safety, hot & high performance, drift down over high terrain, blah blah blah...
Airline management around the world (and particularly in Australia) don't give a flying
about which one might be safest.
All these aircraft are certified to a minimum required standard, and therein ends their thoughts on it.
They choose the cheapest one. Period.
If you could build a six engine airliner with the same payload as a 777 which was 1% cheaper overall (considering purchase price, maintenance, fuel efficiency, staff costs etc. etc.) the 777 would go the way of the dodo faster than you could say "Here comes another management bonus".
Airline management around the world (and particularly in Australia) don't give a flying
about which one might be safest.All these aircraft are certified to a minimum required standard, and therein ends their thoughts on it.
They choose the cheapest one. Period.
If you could build a six engine airliner with the same payload as a 777 which was 1% cheaper overall (considering purchase price, maintenance, fuel efficiency, staff costs etc. etc.) the 777 would go the way of the dodo faster than you could say "Here comes another management bonus".