A 380 saving weight diet or is a trend
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Joined: May 2002
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From: still in bed
A 380 saving weight diet or is a trend
I have noticed that in the A380 the are only 2 hydraulic systems (Green and Yellow)
How big is the weight saving at expenses of redundancy and Airbus family concept of strong functional commonality?
Since Concorde fly by wire we had the Blue hydraulics too.
A 380 is a fantastic heavy flying achievement but I have watched with anxiety its contaminated surface landings. Without the help of ENG 1-4 reverse trust (not equipped) with only a couple of pair extra brakes than the 340-600 the runway must be very long indeed.
Is a saving weight diet necessity or a trend?
Boeing to save weight have completely designed the 787 without air bleed system.
4+2 (APU) heavy weight electric generator will take the job even for pressurization.
(Better for our dried/draying skins)
A part to distant physically (on the A380 flight deck) the two switches (Parking Brake and Out board Camera system) as a result (I believe) of the ZSPD china incident, all those new designs are very smart or very stupid?
How big is the weight saving at expenses of redundancy and Airbus family concept of strong functional commonality?
Since Concorde fly by wire we had the Blue hydraulics too.
A 380 is a fantastic heavy flying achievement but I have watched with anxiety its contaminated surface landings. Without the help of ENG 1-4 reverse trust (not equipped) with only a couple of pair extra brakes than the 340-600 the runway must be very long indeed.
Is a saving weight diet necessity or a trend?
Boeing to save weight have completely designed the 787 without air bleed system.
4+2 (APU) heavy weight electric generator will take the job even for pressurization.
(Better for our dried/draying skins)
A part to distant physically (on the A380 flight deck) the two switches (Parking Brake and Out board Camera system) as a result (I believe) of the ZSPD china incident, all those new designs are very smart or very stupid?
Joined: Dec 2005
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From: Rural Virginia
Every manufacturer looks for new ways to improve their a/c systems, etc, and reduce weight wherever possible while proving a new design. Weight savings on the airframe means more revenue carrying capability (freight and pax) and less fuel spent pushing the plane through the air, especially taking off which uses more fuel per minute than any other sector of flight.
That being said:
- Airbus chose to go from 3 hydraulic systems to 2 in order to simplify the design and maintainability, and reduce weight. Also, the pressure of those systems increased from 3000 psi to 5000 psi (as in fighter jets), and the lines are much thinner, translating into weight savings by lack of an additional hyd fluid reservoir, pumps/filters and associated plumbing and fluid.
- The lack of outboard thrust reversers is also for weight reduction, simplification, and reducing the possibility of FOD being sucked into the engines on the taxi- and runways, since the a/c is so wide.
Stopping the A380 isn't that big a deal - it's going slower on landing than it appears.
Weight reduction and simplification are always part of the design; achieving them is the hard part.
Hope that I answered most of your inquiry to your satisfaction.
Cheers, y'all.
That being said:
- Airbus chose to go from 3 hydraulic systems to 2 in order to simplify the design and maintainability, and reduce weight. Also, the pressure of those systems increased from 3000 psi to 5000 psi (as in fighter jets), and the lines are much thinner, translating into weight savings by lack of an additional hyd fluid reservoir, pumps/filters and associated plumbing and fluid.
- The lack of outboard thrust reversers is also for weight reduction, simplification, and reducing the possibility of FOD being sucked into the engines on the taxi- and runways, since the a/c is so wide.
Stopping the A380 isn't that big a deal - it's going slower on landing than it appears.
Weight reduction and simplification are always part of the design; achieving them is the hard part.
Hope that I answered most of your inquiry to your satisfaction.
Cheers, y'all.
Thread Starter
Joined: May 2002
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From: still in bed
Yes, you have done. Thank you!
Do you have the Vref (adverage) for the a380?
the point I was making is that I will probably avoid to fly in an airplane where save weight economics are like using a thinner wire to suspend a blade over my head.
5000 psi (like the Concorde, and the B787 after all) in order to carry less fluid and using thinner pipes is a technical achievement that I wonder is really needed because the airplan is too fat to be safe.
As pasenger instead I am looking foward to fly on the B787 where more Safety/attention to passengers than "size" in term of advanced technlogy and enviroment enhancement for the "customer" is at least has been advertised.
Do you have the Vref (adverage) for the a380?
the point I was making is that I will probably avoid to fly in an airplane where save weight economics are like using a thinner wire to suspend a blade over my head.
5000 psi (like the Concorde, and the B787 after all) in order to carry less fluid and using thinner pipes is a technical achievement that I wonder is really needed because the airplan is too fat to be safe.
As pasenger instead I am looking foward to fly on the B787 where more Safety/attention to passengers than "size" in term of advanced technlogy and enviroment enhancement for the "customer" is at least has been advertised.
Eidolon
Joined: May 2001
Posts: 2,244
Likes: 62
From: Some hole
Yes, you have done. Thank you!
Do you have the Vref (adverage) for the a380?
the point I was making is that I will probably avoid to fly in an airplane where save weight economics are like using a thinner wire to suspend a blade over my head.
5000 psi (like the Concorde, and the B787 after all) in order to carry less fluid and using thinner pipes is a technical achievement that I wonder is really needed because the airplan is too fat to be safe.
As pasenger instead I am looking foward to fly on the B787 where more Safety/attention to passengers than "size" in term of advanced technlogy and enviroment enhancement for the "customer" is at least has been advertised.
Do you have the Vref (adverage) for the a380?
the point I was making is that I will probably avoid to fly in an airplane where save weight economics are like using a thinner wire to suspend a blade over my head.
5000 psi (like the Concorde, and the B787 after all) in order to carry less fluid and using thinner pipes is a technical achievement that I wonder is really needed because the airplan is too fat to be safe.
As pasenger instead I am looking foward to fly on the B787 where more Safety/attention to passengers than "size" in term of advanced technlogy and enviroment enhancement for the "customer" is at least has been advertised.
The wall thickness of the pipes in most cases will not be thinner, actually thicker. To carry the required force in the hydraulics to operate the controls etc you either need a lot more 3000 psi fluid (meaning larger diameter pipes and more fluid) or less 5000 psi fluid which can carried in smaller diameter pipes. The reference to thickness above should be diameter, not wall thickness of the pipes.
As a 787 passenger you maybe interested in reading this Boeing focuses on weight not rate, easing back on production study to focus on lighter twinjet,
ramping up spending on weight-saving initiatives to close the gap with its original targets
Joined: Jul 2005
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From: Australia
As I understand, the redundacy of the system is maintained by using small electric servo motors on each flight control surface in case of dual hydraulic failure. Is anyone able to give me any more detail on this?
Thanks
Henry.
Thanks
Henry.
Joined: Feb 2001
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From: Newcastle, WA, USA
[QUOTE=swh;2817123]A380 Vref is about 140 kt at MLW (386t), 748/77W is about 160 kt.
Actually, Vref for the 773ER is about 150 kt. It has the wing area disadvantage of being a stretch airplane.
Vref for the A389 will be considerably higher than 140 kt.
Actually, Vref for the 773ER is about 150 kt. It has the wing area disadvantage of being a stretch airplane.
Vref for the A389 will be considerably higher than 140 kt.
Eidolon
Joined: May 2001
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From: Some hole
As a result of flight testing the A380-800 has come in under its predicted Vref, how do you know what a A380-900 will do ?
Joined: Jan 2005
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From: north
The stretched acf have higher Vspeeds and Vref for the same weight to avoid tailstrike.
In addition, a longer fuselage will increase LIFT, so a stretched acf will have a lower
AoA on landing for the same weight.
The 773ER has added a raked winglet compared to the 773, so it should help
a bit on the speeds
Cheers,
M
PS: On the B789, they will stretch the wing as well, so the above will probably
not be true there
In addition, a longer fuselage will increase LIFT, so a stretched acf will have a lower
AoA on landing for the same weight.
The 773ER has added a raked winglet compared to the 773, so it should help
a bit on the speeds
Cheers,
M
PS: On the B789, they will stretch the wing as well, so the above will probably
not be true there
Last edited by XPMorten; 2nd September 2006 at 13:45.
Joined: Feb 2001
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From: Newcastle, WA, USA
Hint: If the A389 is to have a greater payload than the A388, its max. landing wt. must be greater than the A388 to carry the greater payload and the associated structural wt. increase.
As far as the 773ER approach speed is concerned, why are you quoting a speed associated with alternate landing flap (F25) or non-normal landing flap (F20)? At the prime landing flap position (F30), the MLW Vref is 150 kt.
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From: UK
I have watched with anxiety its contaminated surface landings. Without the help of ENG 1-4 reverse trust (not equipped) with only a couple of pair extra brakes than the 340-600 the runway must be very long indeed.
Joined: Jun 2005
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From: NY
Two hyd. systems
and NO ARTIFICIAL FEEL 
when are they gonna learn to build reusable planes?
Radio Displacement... Height... Incidence...Attitude...Rate of Decent... Altitude...Power Setting...Radio Displacement... Height... Incidence...Attitude...Rate of Decent... Altitude...Power Setting...
rhov
and NO ARTIFICIAL FEEL when are they gonna learn to build reusable planes?
Radio Displacement... Height... Incidence...Attitude...Rate of Decent... Altitude...Power Setting...Radio Displacement... Height... Incidence...Attitude...Rate of Decent... Altitude...Power Setting...
rhov
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From: Newcastle, WA, USA
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From: OZ
Not sure of my sources but
It could be argued that the 380 has 3 hydraulic systems as the rudder is driven by a power pack. An all in one hydrailic pumpS and servo unitS. fighter style type unit.
With the above statement in mind what drives the horizontal stab as it would seem odd to plum hydraulics to the stab but not to the rudder??
It could be argued that the 380 has 3 hydraulic systems as the rudder is driven by a power pack. An all in one hydrailic pumpS and servo unitS. fighter style type unit.
With the above statement in mind what drives the horizontal stab as it would seem odd to plum hydraulics to the stab but not to the rudder??
Thread Starter
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From: still in bed
Joined: Feb 2001
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From: Newcastle, WA, USA
