A380 Main Landing Gear

[Vibes]

Hi All,

Can anyone shed some light as to why the main landing gear bogey for the A380 tilts forwards compared to that of say the A330/A340/B777 which tilts backwards when the main landing gear is extended in mid-air?Does it have any benefits or performance gains by having it tilt forwards?

Warmest Regards,
Vibes

[Bolty McBolt]

Why does the gear tilt....

So the landing gear fits into the langing gear wheel well when the gear is retracted.

[engineer07]

Vibes,

The bogie of the landing gear is positioned when the gear is extended by a pitch trimmer (hydraulic actuator). On the A330/340 a/c the Main (Wing) landing gears are tilted 'tail down' as they have a load carrying capability even when the front wheel are not on the ground - this improves takeoff performance. The B777-300 also has a similar but simpler system.

On the A380 there is no load carrying capacity when all wheel are not on the ground. The choice of positioning of the bogie for landing is usually made due to loads considerations - high loads occur as the wheels touch down and spin up due to gyroscopic forces.

I assume you are referring to the Body Landing gears on the A380 ? These are positioned 'nose down' for landing (by a pitch trimmer which is fully extended). On retraction this pitch trimmer retracts and positions the bogie 'nose up' so that the gear fits into the landing gear bay. Landing with the bogie 'nose up' is a failure case (of the pitch trimmer) which generates higher loads.

[Bolty McBolt]

The bogie of the landing gear is positioned when the gear is extended by a pitch trimmer (hydraulic actuator). On the A330/340 a/c the Main (Wing) landing gears are tilted 'tail down' as they have a load carrying capability even when the front wheel are not on the ground - this improves takeoff performance. The B777-300 also has a similar but simpler system.


You learn something new everyday but it does not explain the 767 and the 777 bogie is angled so that wheels all leave the ground pretty much same time during TO/Rotation and landing is pretty much same.
Spend a few days being offloaded on staff travel in Changi and you become very familiar with the comings and goings of the 777 :ok:

[Rainboe]

Yes it does explain it! There is no other consideration apart from tucking a very large landing gear truck and leg into a tight wheel well.

[Bolty McBolt]

Yes it does explain it! There is no other consideration apart from tucking a very large landing gear truck and leg into a tight wheel well

Nice rainbow but you jumped the gun, I was hoping to glean more incredible facts from engineer07 before he was shot down. :ok:

[Rainboe]

Nobody shot Engineer down. His explanation was very elegant. It was you who refused to accept it and i pointed it it did answer your query. Who shot anyone down pray?
You learn something new everyday but it does not explain the 767 and the 777 bogie is angled so that wheels all leave the ground pretty much same time during TO/Rotation and landing is pretty much same.
I simply pointed out to you that his explanation covered your point, but you seemed to have trouble believing it! Do you understand now?