ConcordeBoy
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 9:58 am

I'm aware that most 772LR orders have been for/with minimal tankage for that derivative...

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...anyone know of any 77L orders for full or partial optional tankage?
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Stitch
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 10:07 am

The advantages of the 77L are more for the extra payload it can fly the same distance as a 77E than the extra distance it can fly over a 77E, which is why most folks don't take the extra tanks as it just cuts down on that extra payload volume.

[Edited 2007-09-29 03:07:43]
 
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sammyk
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 11:08 am

I heard that some of the later deliveries for Air India have the extra tank option. Any truth to that?
 
Yellowstone
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 11:39 am

What is the range difference/max payload difference between the versions with and without the extra tanks?
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worldtraveler
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 11:54 am

The 777ER based on fuel volume already has over 8000 miles of range or nearly 18 hours of flying time. The limiting factor is takeoff weight with a full passenger payload. The LR provides more than enough weight to take off with full fuel tanks based on what is on the ER, a full passenger load, 40-50K pounds of cargo, and do it all from a hot airport, where many 8000 mile destinations are located.

The LR is quite simply an absolutely incredible machine. Compare the performance charts between the ER and LR on Boeings website and see for yourself.

I believe the extra tanks can be added relatively easily later on although they aren't designed to be pulled on and off.
 
max999
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 12:04 pm

Quoting WorldTraveler (Reply 5):
The LR is quite simply an absolutely incredible machine. Compare the performance charts between the ER and LR on Boeings website and see for yourself.

Boeing's range chart for the LR is for the version with all three optional fuel tanks. What's the performance w/o the tanks?
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ikramerica
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772LRs Fuel Tank Options?

Sat Sep 29, 2007 12:12 pm

Quoting Stitch (Reply 2):
The advantages of the 77L are more for the extra payload it can fly the same distance as a 77E than the extra distance it can fly over a 77E, which is why most folks don't take the extra tanks as it just cuts down on that extra payload volume.

Not just that. It can fly MZFW missions on routes that the 77E can only fly max fuel missions. The 77L can fly 7500nm at MZFW, which means it can carry a full payload on routes like YVR/LAX-SYD or ATL-SHA, full cargo, full pax, no restrictions, nearly 365 days a year. This is why DL is buying them. They will compete on these routes by taking more payload than any other carrier in the world (to SHA and to SYD if they decide to start it), as will AC on the YVR route.

As a comparison, UA often has to leave cargo and pax behind on the 744, and that's off of their already restricted planning to SYD. So does QF, though the ERs help a bit.

The downside of course is the 77L uses more fuel per pax, but if it can make up for it in cargo revenue, then it's a good deal.

Quoting Max999 (Reply 6):
Boeing's range chart for the LR is for the version with all three optional fuel tanks. What's the performance w/o the tanks?

It should have the same shape, but the second inflection point is at about 8700nm, not 9400nm. This is because that is the Max Fuel point. Not having the extra tanks doesn't alter the MZFW range, since at MZFW, you can't fill the tanks full and stay under MTOW.

Most people in the know say that each aux tank adds 350nm of range when the added weight of the tank and the fuel is taken into account.
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ConcordeBoy
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RE: 772LRs Fuel Tank Options?

Sat Sep 29, 2007 2:56 pm

Quoting WorldTraveler (Reply 4):
I believe the extra tanks can be added relatively easily later on

...thing is, you have to take the aircraft with the optional pipe/duct/pumps for the auxiliary tanks already in place at delivery, even if the tank(s) are not included/installed. If a "base" model 772LR is ordered, it will not have any of the above for the extra tankage, in order to save weight, and it would certainly not be "relatively easy" to install later.

What I'm curious as to, is:
most/all of the 77Ls currently built are aux tankless... but are they pre-ducted? If so, for how many tanks? Interestingly enough, from what I've been told-- Boeing will build the plane with pre-piping/ducting work for either 1 auxiliary tank or 3, but not just two.
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tdscanuck
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 1:15 am

Quoting ConcordeBoy (Reply 7):
What I'm curious as to, is:
most/all of the 77Ls currently built are aux tankless... but are they pre-ducted? If so, for how many tanks?

The ducting isn't really tank-dependant. The tanks closest to the center wing box (back of the forward cargo bay and front of the aft cargo bay) get plumbed to the center wing tank. All other aux tanks connect to the tank beside them. In the extreme case (a BBJ), the on-aircraft plumbing is the same for 3 tanks or 9. All the other stuff is just interconnection between tanks.

Tom.
 
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calpsafltskeds
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 4:09 am

Obviously, the 772LR has a greater payload and range than the 772ER. It has something like 17% more thrust.

Some have stated in previous threads that the 772LR is more efficient as well. This doesn't seem to make sense as the LR is 26,000 lbs heavier. Ikramaerica states that the 772LR costs more fuel per passenger, which makes sense to me. However, if the older thread was correct in that the LR was more efficient, would it not be the newer wing design and why are they not available for new 772ER models or retrofit?

Do all the airlines fly the 772ER/LR at mach .84 as stated in the charts and what range increase can be made with a slower speed?
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sunrisevalley
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 5:06 am

There is much useful "stuff" particularly by Widebodyphotog at this link>
RE: AC Re-confirms 777, 787 Order (by ZK-NBT Nov 11 2005 in Civil Aviation)

Also there is a link in one of WBP's postings on that topic to a 77L versus a 772 payload/range chart.
 
ConcordeBoy
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 7:26 am

Quoting CALPSAFltSkeds (Reply 9):
Ikramaerica states that the 772LR costs more fuel per passenger

IINM, he wasn't comparing it to the 772ER

Quoting CALPSAFltSkeds (Reply 9):
newer wing design

...there is none

Quoting CALPSAFltSkeds (Reply 9):
why are they not available for new 772ER models or retrofit?

...because APB doesn't have/cannot use the design patent
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ikramerica
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 7:42 am

Quoting CALPSAFltSkeds (Reply 9):
Ikramaerica states that the 772LR costs more fuel per passenger, which makes sense to me.

I was comparing to the 744. The 772LR uses more fuel per pax than a 744. But on a 6700nm route, the 772LR can take a 100% load factor plus full gross weight of cargo, should the airline want, flying southwest to Australia, while the 744 would be carrying maximum fuel and be cargo limited.

Quoting ConcordeBoy (Reply 11):
...because APB doesn't have/cannot use the design patent

Actually, APB is looking at doing a 77E winglet, but the 767 had more demand so they are certifying that first. They also looked at the 744, replacing the winglet with a 20 foot tall blended job, but there was not a lot of interest, IIRC. But there are airlines like AA and CO and NZ and JL and NH with newer 772s that are going to want to use them for a while, so winglets may end up coming within the next 5 years.
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Flighty
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 8:13 am

Quoting Ikramerica (Reply 12):
But there are airlines like AA and CO and NZ and JL and NH with newer 772s that are going to want to use them for a while, so winglets may end up coming within the next 5 years.

I'd say there would be a lot of interest in 777-200ER winglets. The fuel savings alone (at 5%) would be very worthwhile.

Then, you've got cargo and range benefits for CO and DL and others who push the 772ER to the limits.

Winglets would extend the 772ER's life in the face of not only the 77L, but the A350.

We have already seen that DL and AA believe the B763-winglet can compete against the B788. They'll be flying those till nearly 2018 or so...
 
sunrisevalley
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 11:40 am

Quoting Flighty (Reply 13):
I'd say there would be a lot of interest in 777-200ER winglets. The fuel savings alone (at 5%) would be very worthwhile.

But can this be done without strengthening the wing and adding weight? I don't think so. I believe there is a thread on this topic in the archives somewhere.
 
ConcordeBoy
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 12:18 pm

Quoting Ikramerica (Reply 12):
Actually, APB is looking at doing a 77E winglet,

Which, I might add, has very little to do with my statement other than the fact that they do not have what it'd take to install raked wingtips on any aircraft.

Quoting Ikramerica (Reply 12):
but the 767 had more demand so they are certifying that first.

Probably because......

Quoting Flighty (Reply 13):

I'd say there would be a lot of interest in 777-200ER winglets.

.....there was practically zilch, which is why they went to the 767, which did have quite a bit.

The 777 is the in-service wing par excellence, and the efficiency-increase:cost ratio will be significantly thinner than any such project before it, if even realistically plausible at all. I'm hoping that hasn't changed, thereby increasing the likelihood that..........

Quoting Ikramerica (Reply 12):
so winglets may end up coming

.....never happens.
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ikramerica
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 2:13 pm

Quoting ConcordeBoy (Reply 15):
Which, I might add, has very little to do with my statement other than the fact that they do not have what it'd take to install raked wingtips on any aircraft.

Who's talking about raked wingtips? APB installs blended vertical wingtips.

The demand for 777 wingtips will come as more efficient planes enter service. Right now, the 777 is one of the more efficient birds out there, but as the 787s and A350s enter service, that extra 3-5% fuel savings to extend the life of the 777 looks more desirable. Right now, they would only be about saving cash in the abstract, but in the future, they would be a way for newer 777s to stay competitive on routes where other carriers are flying more modern planes.

Quoting ConcordeBoy (Reply 15):
.....never happens.

The 772-ER is only a 10 year old airframe. The 763ER is 20 years old, and only now is there a winglet being developed for it. Give the 777 5 more years, and demand will come.

Never say never. The "lack of interest" is nothing more than sorting the order for the products. Highest demand was the 737, then the 757, then the 767, followed by the 777. Since APB has limited resources and design/test capacity, they can't just do them all at once.
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calpsafltskeds
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 2:28 pm

Quoting Ikramerica (Reply 16):
Right now, they would only be about saving cash in the abstract, but in the future, they would be a way for newer 777s to stay competitive on routes where other carriers are flying more modern planes.

That doesn't seem to make sense. Airlines would love to save 3-5% on any aircraft and with the 772ER such savings would translate into fuel savings, payload increases, increased range or a combination of the three. Several airlines flying the 772ER near its range on routes like EWR-DEL, EWR-BOM, EWR-HKG, EWR-PVG would undoubtedly want such an improvement and why would they lose 3 years of savings just because the 787 hasn't been delivered. Te savingws would be real, not abstract.

Quoting ConcordeBoy (Reply 11):
Quoting CALPSAFltSkeds (Reply 9):
newer wing design

...there is none

The Boeing website show the 772LR with a 212 ft wingspan and the 772ER at 199 ft. I believe this is the ranked wingtips that I alluded to in Reply 9, stating that the 772LR must have a better wing design for ULH operations to carry that 26,000 lbs. extra empty operating weight of the 772LR. Would it make sense that the upgraded GE engines at a higher thrust would be more economical than the 94,000 lb version.
So, my point is that many airlines would love those 3-5% savings if available with raked wingtips or winglets. Could it be that there's not enough airframes to convert vs. the 73F/738 fleets?
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tdscanuck
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 2:45 pm

Quoting CALPSAFltSkeds (Reply 9):
Some have stated in previous threads that the 772LR is more efficient as well.

It's aerodynamically more efficient, which isn't the same as less fuel burn per passenger.

Quoting ConcordeBoy (Reply 11):
Quoting CALPSAFltSkeds (Reply 9):
newer wing design

...there is none

It is slightly different.

Quoting Flighty (Reply 13):
Quoting Ikramerica (Reply 12):
But there are airlines like AA and CO and NZ and JL and NH with newer 772s that are going to want to use them for a while, so winglets may end up coming within the next 5 years.

I'd say there would be a lot of interest in 777-200ER winglets. The fuel savings alone (at 5%) would be very worthwhile.

It's very unlikely you could get 5% fuel savings with a 777 winglet.

Winglets only work well if the wing has positive margin of safety already (i.e. it's overdesigned). The 777 wing is very very well designed, which is another way of saying that it's margin of safety is very very close to zero. That puts a severe dent in the amount of economy you can get from a winglet. Given that a 777 is rarely span-constrained, raked wingtips would probably more productive as a retrofit anyway.

Tom.
 
ConcordeBoy
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RE: 772LRs Fuel Tank Options?

Sun Sep 30, 2007 4:36 pm

Quoting Ikramerica (Reply 16):

Who's talking about raked wingtips?

I was, if you'd pay attention

Quoting Ikramerica (Reply 16):
that extra 3-5% fuel savings

How do you figure on this number? Doubtful it'd be anywhere near that amount for the 777

Quoting Ikramerica (Reply 16):
and demand will come.

Again, why do you assume that what minuscule savings could be gained from a 777 blended winglet, would be worth the cost to the carriers?

Remember, routes such as EWR-HKG, CAN-LAX, etc were already in service for years when last this was proposed to the airlines, and they weren't interested.

Quoting Tdscanuck (Reply 18):
It is slightly different.

with fortification to the original design being the overwhelming factor of difference, not to much a deviation from said design
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