a380900
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Shorter Vertical Stabilizer For The A380-900?

Sun Jan 29, 2012 2:32 pm

Depending on its length (80m? 88m?), do you have an idea of how much shorter the vertical stabilizer of the A380-900 would need to be? And its horizontal stabilizer? How much weight could be gained?
 
prebennorholm
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RE: Shorter Vertical Stabilizer For The A380-900?

Mon Jan 30, 2012 12:33 am

Not much.

The -900, if it ever is built, is likely to utilize the heavier MTOW and more powerful engines which were planned for the cargo version.

It will still have to deal with the even more massive asymmetric thrust of an outer engine shut down after V1 speed. That will demand even more rudder authority than the -800. The longer moment arm comes in handy.

My guess would be that they will use the same tail components, as they do on A320 and a321, A330-200 and A330-300.

Alternative tail feathers are normally only seen on extreme shrinks such as A318 and B747SP.
Always keep your number of landings equal to your number of take-offs
 
a380900
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RE: Shorter Vertical Stabilizer For The A380-900?

Mon Jan 30, 2012 1:00 am

You seem to be right. I thought changing the tail size depending on the length of the fuselage was much more common. In fact it is quite rare.

Now it is often said that the A380-800 is to the A380 family what the A318 is to the A320 family. And one has to admit the tail is enormous. So maybe my question is still valid... Yet you are right, no difference among A319/A320/A321. No difference between A340-500 and A340-600. Maybe one between A340-200 and A340-300. But in most cases, the tail remains the same across the families. Too bad cause the longer A380 would have looked slicker with a smaller tail. Maybe if it's 15m longer!
 
slz396
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RE: Shorter Vertical Stabilizer For The A380-900?

Mon Jan 30, 2012 8:33 am

Quoting prebennorholm (Reply 1):
they will use the same tail components, as they do [...] on A330-200 and A330-300.

The A333 does have a different tail from the A332, you know?
 
a380900
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RE: Shorter Vertical Stabilizer For The A380-900?

Mon Jan 30, 2012 10:47 am

Quoting slz396 (Reply 3):
The A333 does have a different tail from the A332, you know?

That is true: the height given by Airbus for the A332 is 1740 in the wikipedia drawing of the plane, 1685 for the A333. So the A333 tail is at least 55cm smaller. "At least" because as we know the A330 is slightly pointing down when on the ground so the longer A333 should have a higher tail if both tails were the same.
 
rheinwaldner
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RE: Shorter Vertical Stabilizer For The A380-900?

Thu Feb 02, 2012 7:33 am

Quoting a380900 (Reply 4):
"At least" because as we know the A330 is slightly pointing down when on the ground so the longer A333 should have a higher tail if both tails were the same.

I don't think because if the gears have equal length, the longer the fuselage the smaller the angle when on the ground.
 
LH707330
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RE: Shorter Vertical Stabilizer For The A380-900?

Sun Jul 15, 2012 7:20 pm

Quoting a380900 (Reply 2):
No difference between A340-500 and A340-600. Maybe one between A340-200 and A340-300.

The A342, 343, and 333 have the same (short) fin, while the 332, 345, and 346 got the tall one. Even though the 345 and 346 have a longer moment arm, the Trents are far more powerful than the hair dryers on the 342/343. Boeing had to change the rudder on the 748 to a double-hinge to regain authority, despite the fact that they stretched the aft fuselage (1.6m IIRC). My guess is that the 744 was at the absolute limit with its 62k engines and a rudder designed for 43k JT9Ds from the 741, so the 67k GEnX on the 748 necessitated the change.

With the 389, I suspect they'll keep the same fin as the 388, because the moment arm and extra engine thrust will cancel more or less. My guess is that the Airbus guys did their homework and future-proofed the fin for use with the 389 the same way they overbuild the 388 wings for a larger MTOW. That way, if they do go with the stretch, they can keep the production process the same without having to twiddle with anything.

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