MoKa777 wrote:

None of us, not even Boeing, probably could have foreseen Airbus improving the A35K to the point where it will have 77L/8 rivalling range (maybe not exact range but close enough).

The thing that makes the 778 special doesn't seem so special anymore.

RJMAZ wrote:

MoKa777 wrote:

None of us, not even Boeing, probably could have foreseen Airbus improving the A35K to the point where it will have 77L/8 rivalling range (maybe not exact range but close enough).

The thing that makes the 778 special doesn't seem so special anymore.

This is a bit ridiculous.

The A35K hasnt even reached the 777L range and is 1000nm short of the range of the 777-8 with the same payload. Boeing didnt have to forsee anything the 777-8 is still a step above anything on the market.

A 3T MTOW increase is required to match the 777L.
A 15T MTOW increase is required to match the 777-8.
The first increase is possible the second is a pipedream.

Mrakula wrote:

You are probably right but when you calculate fuel burn per hour from your calculation B777-8 will burn at least 5% more fuel per hour than A350-1000 that is big diffrence.

StTim wrote:

Why aren’t the airlines signing up for 778’s then? It is a very nice plane.

Stitch wrote:

tomcat wrote:

An A359 fuselage with the A35K wing / landing gear / engine would be a very interesting basis for a freighter.

At launch, Airbus discussed a possible future A350-900F using the landing gear, operating weights (at the time, 295,000kg) and engines from the A350-1000.

RJMAZ wrote:

Mrakula wrote:

You are probably right but when you calculate fuel burn per hour from your calculation B777-8 will burn at least 5% more fuel per hour than A350-1000 that is big diffrence.

The 778 might burn less fuel than the A35K

The 777-8 definitely wont burn 5% or more fuel per hour. I would estimate the 778 will burn within 1% of the fuel of the A35K when taking the same payload the same distance.

Fuel burn is easy to calculate. You need surface drag, lift to drag ratio and engine SFC.

The 778 and A35K fuselages have equal drag, identical volume and wetted area. To push them through the air requires the same amount of thrust.

Aircraft flying weight has a lot to do with fuel burn. Add 40T of payload and 120T of fuel to both aircraft and the A35K will weigh 315T and the 778 will weigh 328T. The 778 will weigh only 4% more. So far the 778 should burn 4% more fuel but that would assume the wings and engines are the same.

Now the wings come next as they are used to determine lift to drag ratio. Each A35K wing has a span of 29.38m. Each 778 wing is 32.8m. The 778 has a massive 12% greater wingspan. This wingspan advantage gives it a superior lift to drag ratio. It would easily offset that 4% weight disadvantage when it comes to the amount of thrust required to push it through the air. Fuel burn is probably close to identical at this stage.

Last but not least we have engine SFC. The GE9X is predicted to have slightly better fuel burn than the trent XWB. This would then allow the 778 to burn less fuel than the A35K.

So when the A35K is at maximum takeoff weight the 778 would be around 20T below its maximum takeoff weight while taking the same payload the same distance. This allows the 778 to tank an extra 20T of fuel to fly 1000nm further or load the belly with cargo. On a 7000nm route the 778 would be able to carry 40% more payload while having sinilar fuel burn.

Mrakula wrote:

In terms of drag cross section of B777 has more drag than A350.

Mrakula wrote:

In general, more wing span and area has also more drag but it depends also on a profile of the wing.

Mrakula wrote:

Bigger engines more drag also. Heavier frame needs more lift and it comes with more drag in general. Engines will have slightly better SFC but also more thrust so fuel burn per hour could be higher anyway. Also climbing of the heavier A/C consumes more fuel.

Mrakula wrote:

B778 can lift more payload further but it could burn more fuel. If burn similair fuel with 40% more paylod Ohhh Jesus it will be huge diffrence and A35K will be left in the ashes:-)

RJMAZ wrote:

Mrakula wrote:

In terms of drag cross section of B777 has more drag than A350.

Cross section only plays a small part. The length of the tube is also very important. The A350 is a longer tube so total fuselage drag is nearly identical between the two. For instance the 787-10 has more drag than the 787-9 if both aircraft are at the same max takeoff weight the 787-10 will require more thrust to move through the air.

Mrakula wrote:

In general, more wing span and area has also more drag but it depends also on a profile of the wing.

Wing area is nearly identical but the 777-8 has a massive aspect ratio advantage. So similar drag but greater lift in favour of the 777-8.

Mrakula wrote:

Bigger engines more drag also. Heavier frame needs more lift and it comes with more drag in general. Engines will have slightly better SFC but also more thrust so fuel burn per hour could be higher anyway. Also climbing of the heavier A/C consumes more fuel.

The 777-8 wing produces more lift than than the 4% weight increase. It will be able to climb faster while burning less fuel. Thats how lift to drag ratio works.

The 777-8 will have less drag than the 777-9 due to the shorter fuselage and less wetter area. So with equal engines it means the 777-8 is slightly overpowered. This will allow it to climb quicker and fly higher reducing fuel burn.

The A35K has a lower service ceiling than the A359 partly due to the smaller wing on the larger frame.

Mrakula wrote:

B778 can lift more payload further but it could burn more fuel. If burn similair fuel with 40% more paylod Ohhh Jesus it will be huge diffrence and A35K will be left in the ashes:-)

Usually aircraft get a big surge of orders after the first flight. The A35K got no surge which suggests the market demand is not as strong. The 777X has not flown yet so final judgement of its sales success should wait a year after the first flight.

The A350 family has a payload range advantage over the 787. The 777X family has a similar payload range advantage over the A350. Any argument that says the A350 is superior to the 787, that same argument can be used to explain why the 777X is superior to the A350.

tommy1808 wrote:

With the weights the A35k is throwing around now, it probably makes an excellent base for an cargo aircraft. What would fit? 100+LD3, 44LD3+ 30-32 pallets or 44-46 pellets ?

RJMAZ wrote:

Mrakula wrote:

In terms of drag cross section of B777 has more drag than A350.

Cross section only plays a small part. The length of the tube is also very important. The A350 is a longer tube so total fuselage drag is nearly identical between the two. For instance the 787-10 has more drag than the 787-9 if both aircraft are at the same max takeoff weight the 787-10 will require more thrust to move through the air.

787-10 has more powerful engines 76k pounds vs. 787-9 71k pounds.

Mrakula wrote:

In general, more wing span and area has also more drag but it depends also on a profile of the wing.

Wing area is nearly identical but the 777-8 has a massive aspect ratio advantage. So similar drag but greater lift in favour of the 777-8.

A330NEO has higher aspect ratio then 787 and slitl is less efficient.

Mrakula wrote:

Bigger engines more drag also. Heavier frame needs more lift and it comes with more drag in general. Engines will have slightly better SFC but also more thrust so fuel burn per hour could be higher anyway. Also climbing of the heavier A/C consumes more fuel.

The 777-8 wing produces more lift than than the 4% weight increase. It will be able to climb faster while burning less fuel. Thats how lift to drag ratio works.

Where you got 777-8 produce more lift with same wing area??? Still is much heavier!



The 777-8 will have less drag than the 777-9 due to the shorter fuselage and less wetter area. So with equal engines it means the 777-8 is slightly overpowered. This will allow it to climb quicker and fly higher reducing fuel burn.

With same TOW it will climb similair to bigger sibling. Lift with same power cannot go faster then lighter one it is physics:-)

The A35K has a lower service ceiling than the A359 partly due to the smaller wing on the larger frame.

Mrakula wrote:

B778 can lift more payload further but it could burn more fuel. If burn similair fuel with 40% more paylod Ohhh Jesus it will be huge diffrence and A35K will be left in the ashes:-)

Usually aircraft get a big surge of orders after the first flight. The A35K got no surge which suggests the market demand is not as strong. The 777X has not flown yet so final judgement of its sales success should wait a year after the first flight.

The A350 family has a payload range advantage over the 787. The 777X family has a similar payload range advantage over the A350. Any argument that says the A350 is superior to the 787, that same argument can be used to explain why the 777X is superior to the A350.

Stitch wrote:

At launch, Airbus discussed a possible future A350-900F using the landing gear, operating weights (at the time, 295,000kg) and engines from the A350-1000.

Mrakula wrote:

787-10 has more powerful engines 76k pounds vs. 787-9 71k pounds.

Mrakula wrote:

A330NEO has higher aspect ratio then 787 and slitl is less efficient.

Mrakula wrote:

Where you got 777-8 produce more lift with same wing area??? Still is much heavier!

Mrakula wrote:

With same TOW it will climb similair to bigger sibling. Lift with same power cannot go faster then lighter one it is physics:-)

Mrakula wrote:

777X does not flying yet so that is only speculation:-)

Sorry but you bent facts us you like

kevin5345179 wrote:

1. GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......
2. The OEW for 778 is 13 tons more than A35K and that's almost 10% of the OEW. There is no way the fuel burn will be within 1% for same payload and flying same distance. Physics doesn't add up .....

kevin5345179 wrote:

GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......

JustSomeDood wrote:

kevin5345179 wrote:

GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......

What the 77W does against the A35(9) in terms of climb performance is irrelevant, given the 777X will have a much more aerodynamic, higher aspect ratio wing that generates more lift for a given airspeed and altitude. (Not to mention that the A35K has a "worse" wing, aerodynamically speaking, than the A359 due to the lower AR)

JustSomeDood wrote:

What the 77W does against the A35(9) in terms of climb performance is irrelevant, given the 777X will have a much more aerodynamic, higher aspect ratio wing that generates more lift for a given airspeed and altitude.

Planesmart wrote:

JustSomeDood wrote:

What the 77W does against the A35(9) in terms of climb performance is irrelevant, given the 777X will have a much more aerodynamic, higher aspect ratio wing that generates more lift for a given airspeed and altitude.

Wasn't climb performance previously very relevant when comparing the 777 to A340?

RJMAZ wrote:

Mrakula wrote:

You are probably right but when you calculate fuel burn per hour from your calculation B777-8 will burn at least 5% more fuel per hour than A350-1000 that is big diffrence.

The 778 might burn less fuel than the A35K

The 777-8 definitely wont burn 5% or more fuel per hour. I would estimate the 778 will burn within 1% of the fuel of the A35K when taking the same payload the same distance.

Fuel burn is easy to calculate. You need surface drag, lift to drag ratio and engine SFC.

The 778 and A35K fuselages have equal drag, identical volume and wetted area. To push them through the air requires the same amount of thrust.

Aircraft flying weight has a lot to do with fuel burn. Add 40T of payload and 120T of fuel to both aircraft and the A35K will weigh 315T and the 778 will weigh 328T. The 778 will weigh only 4% more. So far the 778 should burn 4% more fuel but that would assume the wings and engines are the same.

Now the wings come next as they are used to determine lift to drag ratio. Each A35K wing has a span of 29.38m. Each 778 wing is 32.8m. The 778 has a massive 12% greater wingspan. This wingspan advantage gives it a superior lift to drag ratio. It would easily offset that 4% weight disadvantage when it comes to the amount of thrust required to push it through the air. Fuel burn is probably close to identical at this stage.

Last but not least we have engine SFC. The GE9X is predicted to have slightly better fuel burn than the trent XWB. This would then allow the 778 to burn less fuel than the A35K.

So when the A35K is at maximum takeoff weight the 778 would be around 20T below its maximum takeoff weight while taking the same payload the same distance. This allows the 778 to tank an extra 20T of fuel to fly 1000nm further or load the belly with cargo. On a 7000nm route the 778 would be able to carry 40% more payload while having sinilar fuel burn.

kevin5345179 wrote:

1. GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......
2. The OEW for 778 is 13 tons more than A35K and that's almost 10% of the OEW. There is no way the fuel burn will be within 1% for same payload and flying same distance. Physics doesn't add up .....

RJMAZ wrote:

Mrakula wrote:

787-10 has more powerful engines 76k pounds vs. 787-9 71k pounds.

Exactly as I said 787-10 has more drag than the 787-9 so it needs nore thrust at the same weight.

Mrakula wrote:

A330NEO has higher aspect ratio then 787 and slitl is less efficient.

The wing tips make the 30 year old A330 wing nearly match a 10 year old 787 wing. Its not the same as the 777X vs A350 which are both recent brand new wings. In this case the wing with the higher aspect ratio wins and the 777X is newer so it will most likely have some newer technology.

Mrakula wrote:

Where you got 777-8 produce more lift with same wing area??? Still is much heavier!

Wingspan is just as important as wing area when it comes to lift. So with equal area the wing with greater span will produce more lift. This is fairly basic aerodynamics.

Mrakula wrote:

With same TOW it will climb similair to bigger sibling. Lift with same power cannot go faster then lighter one it is physics:-)

Climbing has a large portion of horizontal flight. The longer aircraft will have more drag so it will require more thrust to move forward even though the weight is the same. So if the 777-8 and 777-9 both take off a full throttle at 350T weight the 777-8 will climb faster.

Mrakula wrote:

777X does not flying yet so that is only speculation:-)

Sorry but you bent facts us you like

Its pretty easy to calculate.

Mrakula wrote:

As you said 30year old wing wit new wing tips is competing with 10 year old wing. I am not expecting 777X wing and engines can bring enought margin over A350 to make it more efficient with such hevier frame!

ap305 wrote:

As far as performance is concerned AAB already stated that aircraft is beating spec and CX will shortly introduce it on a 17:30 hr mission.

Stitch wrote:

Mrakula wrote:

As you said 30year old wing wit new wing tips is competing with 10 year old wing. I am not expecting 777X wing and engines can bring enought margin over A350 to make it more efficient with such hevier frame!

The 777X wing is based on the 787's wing, not the original 777's wing. So it is on a similar "tech level" as the A350.

waly777 wrote:

kevin5345179 wrote:

1. GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......
2. The OEW for 778 is 13 tons more than A35K and that's almost 10% of the OEW. There is no way the fuel burn will be within 1% for same payload and flying same distance. Physics doesn't add up .....

No offence but i will politely have to call BS on number 1 as performance data has not been publicly released for the 77X and GE9X seems to remain a 105Klb engine. What the 77W lacks in wingspan, it makes up for with excess thrust. The 77X on the other hand has a mild reduction in thrust coupled with a larger and more aerodynamic wing.

How did you arrive at 77W vs 359 climb ability? Same %payload? Same % fuel? Same %derated thrust? Same ATC restrictions? The 77W is no slouch during the climb phase.

anrec80 wrote:

ap305 wrote:

As far as performance is concerned AAB already stated that aircraft is beating spec and CX will shortly introduce it on a 17:30 hr mission.

Hmm - which mission is that? I always thought CX was never into ULH business.

kevin5345179 wrote:

waly777 wrote:

kevin5345179 wrote:

1. GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......
2. The OEW for 778 is 13 tons more than A35K and that's almost 10% of the OEW. There is no way the fuel burn will be within 1% for same payload and flying same distance. Physics doesn't add up .....

No offence but i will politely have to call BS on number 1 as performance data has not been publicly released for the 77X and GE9X seems to remain a 105Klb engine. What the 77W lacks in wingspan, it makes up for with excess thrust. The 77X on the other hand has a mild reduction in thrust coupled with a larger and more aerodynamic wing.

How did you arrive at 77W vs 359 climb ability? Same %payload? Same % fuel? Same %derated thrust? Same ATC restrictions? The 77W is no slouch during the climb phase.

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

OldAeroGuy wrote:

kevin5345179 wrote:

waly777 wrote:

No offence but i will politely have to call BS on number 1 as performance data has not been publicly released for the 77X and GE9X seems to remain a 105Klb engine. What the 77W lacks in wingspan, it makes up for with excess thrust. The 77X on the other hand has a mild reduction in thrust coupled with a larger and more aerodynamic wing.

How did you arrive at 77W vs 359 climb ability? Same %payload? Same % fuel? Same %derated thrust? Same ATC restrictions? The 77W is no slouch during the climb phase.

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

The high wing loading of the 77W is responsible for its low Initial Cruise Altitude, not engine thrust.

The larger wing of the 779 at the same MTOW will give it higher Initial Cruise Altitude than the 77W even if the GE9 has a lower thrust rating compared to the GE90-115B.

kevin5345179 wrote:

waly777 wrote:

kevin5345179 wrote:

1. GE is actually working on increasing GE9X thrust because 777X will climb too slow .... In fact, 77W climb so much slower than A350 flying on the same route. With identical MTOW and further reduction in engine thrust, the performance only gets worse ......
2. The OEW for 778 is 13 tons more than A35K and that's almost 10% of the OEW. There is no way the fuel burn will be within 1% for same payload and flying same distance. Physics doesn't add up .....

No offence but i will politely have to call BS on number 1 as performance data has not been publicly released for the 77X and GE9X seems to remain a 105Klb engine. What the 77W lacks in wingspan, it makes up for with excess thrust. The 77X on the other hand has a mild reduction in thrust coupled with a larger and more aerodynamic wing.

How did you arrive at 77W vs 359 climb ability? Same %payload? Same % fuel? Same %derated thrust? Same ATC restrictions? The 77W is no slouch during the climb phase.

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

kevin5345179 wrote:

OldAeroGuy wrote:

kevin5345179 wrote:

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

The high wing loading of the 77W is responsible for its low Initial Cruise Altitude, not engine thrust.

The larger wing of the 779 at the same MTOW will give it higher Initial Cruise Altitude than the 77W even if the GE9 has a lower thrust rating compared to the GE90-115B.

actually they are related ....
lighter wingload -> better climb rate and less thrust requirement during cruise
which means you can go the opposite direction:
better thrust -> better climb rate and allow higher wingload

anyways, the 777X wing area grows 7% as compare to 77W while thrust of GE9X is only 91% of GE90-115B
7% gain in wingload and 9% lost in thrust while MTOW remained unchanged
I guess no additional comment required

waly777 wrote:

kevin5345179 wrote:

waly777 wrote:

No offence but i will politely have to call BS on number 1 as performance data has not been publicly released for the 77X and GE9X seems to remain a 105Klb engine. What the 77W lacks in wingspan, it makes up for with excess thrust. The 77X on the other hand has a mild reduction in thrust coupled with a larger and more aerodynamic wing.

How did you arrive at 77W vs 359 climb ability? Same %payload? Same % fuel? Same %derated thrust? Same ATC restrictions? The 77W is no slouch during the climb phase.

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

The wingloading is responsible for the initial low altitude not the ability to climb. The 77W has more than enough thrust to take it very quickly to altitude as quickly as other wide body twins if not quicker than most thanks to the engines which over compensate for the perhaps slightly small wing.

By the same logic, are you suggesting the 380 outclimbs the 77W because it has a higher initial cruise altitude? You should check a few in-flight videos and you'll see this is not the case.

kevin5345179 wrote:

waly777 wrote:

kevin5345179 wrote:

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

The wingloading is responsible for the initial low altitude not the ability to climb. The 77W has more than enough thrust to take it very quickly to altitude as quickly as other wide body twins if not quicker than most thanks to the engines which over compensate for the perhaps slightly small wing.

By the same logic, are you suggesting the 380 outclimbs the 77W because it has a higher initial cruise altitude? You should check a few in-flight videos and you'll see this is not the case.

simple logic:
lower wing loading -> slower stall speed -> higher AOA is allow -> faster climb rate

kevin5345179 wrote:

actually they are related ....
lighter wingload -> better climb rate and less thrust requirement during cruise
which means you can go the opposite direction:
better thrust -> better climb rate and allow higher wingload

anyways, the 777X wing area grows 7% as compare to 77W while thrust of GE9X is only 91% of GE90-115B
7% gain in wingload and 9% lost in thrust while MTOW remained unchanged
I guess no additional comment required

kevin5345179 wrote:

waly777 wrote:

kevin5345179 wrote:

heard the #1 from friends in GE

look at full load for both planes and check their climb profile and it'll be pretty obvious; especially 777 is more altitude restricted compare to A350

The wingloading is responsible for the initial low altitude not the ability to climb. The 77W has more than enough thrust to take it very quickly to altitude as quickly as other wide body twins if not quicker than most thanks to the engines which over compensate for the perhaps slightly small wing.

By the same logic, are you suggesting the 380 outclimbs the 77W because it has a higher initial cruise altitude? You should check a few in-flight videos and you'll see this is not the case.

simple logic:
lower wing loading -> slower stall speed -> higher AOA is allow -> faster climb rate

OldAeroGuy wrote:

kevin5345179 wrote:

waly777 wrote:

The wingloading is responsible for the initial low altitude not the ability to climb. The 77W has more than enough thrust to take it very quickly to altitude as quickly as other wide body twins if not quicker than most thanks to the engines which over compensate for the perhaps slightly small wing.

By the same logic, are you suggesting the 380 outclimbs the 77W because it has a higher initial cruise altitude? You should check a few in-flight videos and you'll see this is not the case.

simple logic:
lower wing loading -> slower stall speed -> higher AOA is allow -> faster climb rate

No, slower stall speed does not lead to better rate of climb and the AOA is irrelevant.

Basically, Climb Gradient = (Thrust/Weight-Drag/Lift)/(1+0.467M^2) for a constant Vi climb.

for the takeoff comparison we're talking about:

Thrust: GE9X = 91%GE90-115B
MTOW: 779 = 77W
Drag: 779 = 90%77W (higher wetted area drag is more than offset by the higher span and reduced induced drag along with other aero technology improvements including a variable camber wing
Lift: 779 = 77W

So

779 Thrust/Weight = 91% 77W Thrust/Weight

but

779 Drag/Lift = 90% 77W Drag/Lift

The higher T/W of the 77W is offset by the lower D/L of the 779.

The 779 climb gradient should be at least as good if not slightly better than the 77W.

Casablanca wrote:

A little off topic but just comparing a real world 15 hour flight today on A359....maxed takeoff, zfw limited, hauling 30 tons
same flight time on 77w, maxed out, zfw limited, hauling 44 tons
approx same time on 77LR, hauling 38 tons payload but could take another 23 tons of payload and fuel.
don't have anything on A35k
Just some very rough calculations , and 350K will be better, but wouldn't describe it as a game changer.......slight improvement but for the latest and greatest I would hope so.

Casablanca wrote:

A little off topic but just comparing a real world 15 hour flight today on A359....maxed takeoff, zfw limited, hauling 30 tons
same flight time on 77w, maxed out, zfw limited, hauling 44 tons
approx same time on 77LR, hauling 38 tons payload but could take another 23 tons of payload and fuel.
don't have anything on A35k
Just some very rough calculations , and 350K will be better, but wouldn't describe it as a game changer.......slight improvement but for the latest and greatest I would hope so.

aemoreira1981 wrote:

Airbus should also invite Delta Air Lines and Qantas for their input. D: will eventually need an aircraft that can do ATL-JNB without significant penalty on the worst days, and right now, only the B77L can do it among twinjets (did management at the time ever consider the Airbus A340-500 or -600)? Qantas would want an aircraft that can do SYD-LHR or JFK nonstop both ways in a 3-class configuration (and they have already pushed the B789 to its absolute limit.

Besides the ME3, I can think of these airlines desiring an MTOW increase on the A35K:
Americas: Delta Air Lines
Europe: British Airways (to go to Australia nonstop; the B789 is too sparse), Turkish Airlines (same)
Australasia: Qantas, Air New Zealand (they have stretched the B789 to Chicago but it can't make it to Newark)

Can this be increased to maybe 320-325t?

RJMAZ wrote:

Mrakula wrote:

You are probably right but when you calculate fuel burn per hour from your calculation B777-8 will burn at least 5% more fuel per hour than A350-1000 that is big diffrence.

The 778 might burn less fuel than the A35K

The 777-8 definitely wont burn 5% or more fuel per hour. I would estimate the 778 will burn within 1% of the fuel of the A35K when taking the same payload the same distance.

Fuel burn is easy to calculate. You need surface drag, lift to drag ratio and engine SFC.

The 778 and A35K fuselages have equal drag, identical volume and wetted area. To push them through the air requires the same amount of thrust.

Aircraft flying weight has a lot to do with fuel burn. Add 40T of payload and 120T of fuel to both aircraft and the A35K will weigh 315T and the 778 will weigh 328T. The 778 will weigh only 4% more. So far the 778 should burn 4% more fuel but that would assume the wings and engines are the same.

Now the wings come next as they are used to determine lift to drag ratio. Each A35K wing has a span of 29.38m. Each 778 wing is 32.8m. The 778 has a massive 12% greater wingspan. This wingspan advantage gives it a superior lift to drag ratio. It would easily offset that 4% weight disadvantage when it comes to the amount of thrust required to push it through the air. Fuel burn is probably close to identical at this stage.

Last but not least we have engine SFC. The GE9X is predicted to have slightly better fuel burn than the trent XWB. This would then allow the 778 to burn less fuel than the A35K.

So when the A35K is at maximum takeoff weight the 778 would be around 20T below its maximum takeoff weight while taking the same payload the same distance. This allows the 778 to tank an extra 20T of fuel to fly 1000nm further or load the belly with cargo. On a 7000nm route the 778 would be able to carry 40% more payload while having sinilar fuel burn.

talonone wrote:

What!?!?!?!?!
Let's if I get that clear.
So a plane that has more.weight, a bigger wingspan, a bigger thrust, will be able to carry 40% more payload????

talonone wrote:

Do you have the formula how to build a "perpetum mobile" also!?

RJMAZ wrote:

talonone wrote:

What!?!?!?!?!
Let's if I get that clear.
So a plane that has more.weight, a bigger wingspan, a bigger thrust, will be able to carry 40% more payload????