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?

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.

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.

A380 Vref is about 140 kt at MLW (386t), 748/77W is about 160 kt. The A380 landing distance is under 1900m at MLW. As far as I know landing distance for all aircraft is based on the use of no reverse, this may have been an issue with the 737NG that went off the end of a runway in America.

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,

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.

[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.

At 251t Flap 20 or 25, its 160 plus, the 300 is more like 150 kt, its 13 t lighter on landing.

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 ?

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

Further weight reduction: no IDGs/CSDs on the A380.

Unless Airbus changes the wing on the A389 and/or the A389 weighs the same as the A388, its approach speed will increase relative to the A388.

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.

I don't mean to be a smart ar$e, but a contaminated runway will invariably reduce the actual landing roll distance due to the added retardation effect of the contaminent.:ok:

Two hyd. systems:eek: and NO ARTIFICIAL FEEL:eek: :ouch: :}
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:)

Hydro-planning seldom reduces landing field length.

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??

no IDG's?
 

are you sure? so i suppose A380 will have 4 RATs (maybe behind the engines) to generate power for cooking the meal of 800 people? or a super duracell battery reserve?

No IDGs or CSDs is correct.

380 sports 4 wild frequency generators that each put out more KVA than is available on a 747-400 :ok:

Contaminent does not = hydroplane

A contaminated rwy will increase ROLL friction, but reduce BRAKING friction.

M

And contamination does not guarantee increased retardation for the whole landing roll. Therefore you can't make the blanket statement that the landing distance on a contaminated runway will be reduced.