PDA

View Full Version : AoA of the A330 Main Landing Gear


A330AV8R
28th Feb 2008, 08:27
Hi there

Could someone shed light on what the AoA of the MLG just before touch down is ?

Also does this angle remain constant even if aircraft pitch changes ? I presume it does but just need to be sure

thanks for all inputs

:E

john_tullamarine
28th Feb 2008, 11:36
Folk,

We may not see the point in a question but, so long as the question has a relation to aviation techo stuff, then it's a fair question.

Please, either contribute to the answer, or leave it for others to do so.

Having a go at the poster of the question is not the accepted game ..

The nature of PPRuNe is that often one learns something along the way ... if one is prepared to listen and learn.

Chris Scott
28th Feb 2008, 11:44
Salut airfranz,

Je ne sais pas. En supposant que 82'30 est énigmatique de Blagnac, ou St Martin-du-Touch, je vous propose à marcher chez l'usine pour poser votre question.

[Dunno... Assuming 82'30" is euphemistic of Blagnac, or St Martin-du-Touch, I suggest you walk across to the factory to ask your question.]

Félicitations,

Christophe ;)

A330AV8R
28th Feb 2008, 12:41
Thank you John , and that would be 82'30" E my friend so Im a long way from toulouse = )

thanks again for all inputs save for the extra smart ones .

Chris Scott
28th Feb 2008, 15:16
Hello Air Franz,

I stand corrected! Good luck with your enquiries. I presume you know that, unlike the A300/A310, the A330/A340 seem to have a positive, rather than negative, "AoA". [I suggest "angle of incidence", or "Rigger's angle of incidence", might be a more appropriate term than AoA But I'm sure Messier-Hispano-Bugatti, or whoever designed the L/G, would have a better expression. Could it be called the "angle of dangle" of the truck/bogie, perhaps?]

Sorry I cannot help further; surely someone else will.

Chris

PS

So you are in India, not France... Since this is the technical forum, you will forgive me for pointing out that your stated location, 82' 30", implies "82 minutes, 30 seconds". So now you will understand why I guessed (wrongly?) that you might be in France, specifically at the longitude of the eastern boundary of Toulouse-Blagnac aerodrome (1 degree, 22 minutes, 30 seconds EAST). Blagnac and St Martin-du-Touch are the local towns, and the A330/A340 assembly hall is across the airfield, about 2 km away...

If you wish to avoid navigation error, perhaps you should change your stated location from 82' 30" to 82° 30' ? :)

Reimers
28th Feb 2008, 19:21
The MLG on the A330/A340 is tilted so that the rear axle sits lower than the front axle (assuming aircraft not inverted or similar). The tilt is not adjusted to remain steady to anything on the outside, but remains rather fixed to the aircraft itself

A330AV8R
4th Mar 2008, 14:13
I'm looking for the angle it remains steady at regardless of aircraft pitch . . . .

cheers

forget
4th Mar 2008, 14:23
I'm looking for the angle it remains steady at regardless of aircraft pitch . . . .

That can't be! Are you saying that the bogies move in response to pitch? It may be, like the Lockheed C5, that they move slightly in 'heading' to allow for landings with yaw on - but pitch. :confused: Why would they do that?

PS. Having said that the C5 bogies allow for drift/yaw on landing I've looked it up and - no mention. I didn't dream it!

http://www.baseops.net/c5/gouge/Section1.pdf

PPS. Thank God for that. Found it. The C-5B dispensed with the C-5A's complex crosswind landing gear system.

PPPS. The C5A landing gear bogies may be set at an angle of as much as ±20° from the centerline of the aircraft to simplify takeoff and landing operations in various crosswind conditions.

Chris Scott
5th Mar 2008, 17:16
Hi forget,

I fear your brave attempt to understand airfranz's question, like mine, is a wasted effort. His question remains as unintelligible as his stated location (82'30"). Perhaps he's a busy lad...

TwinAisle
5th Mar 2008, 17:27
A former A330/340 landing gear engineer writes...

I understood the question to mean - what is the angle of the bogie beam in relation to the gear leg? That is pretty much constant, allowing for a few aerodynamic effects. There is a small ram (the pitch trimmer) that gets the bogie in the right position, and more to the point, brings the angle down so that gears are in the correct position for the wheel bays. So the angle in question changes during the extension/retraction process.

BTW - the gear is a Messier Dowty design, proudly built in Gloucester!

I'll try and find the magic number for you, assuming that is the angle you are looking for.

TA

c130jage
5th Mar 2008, 18:16
As twinaisle stated the pitch trimmer is always hydraulically positivly charged keeping the bogie at a positive angle, meaning the rear wheels touch down first. On retraction the bogie is brought back to a horizontal state by the influence of geometry, the shortening mechanism effectivley pulls the slider into the main fitting and geometrically the bogie then sits at 90 degrees to the legs for stowage into the bay. I am not sure of the angle but it is around 10 degrees but i am able to find it out for you tomorrow.

Blip
5th Mar 2008, 22:27
I find it interesting to note that the B767 and the A380 both have bogie beams that tilt forward.

This makes me wonder why the designers choose one over the other and whether it makes any difference to it's functionality or not (transitioning from air to ground and vice versa). It seems the angle can be made to change during extension and retraction so stowagability in the wheel well doesn't seem to be a critical factor.

EMIT
6th Mar 2008, 07:49
Yes, it has to do with stowing gears on retraction.

The bogies are kept at a constant angle relative to the gear legs by an hydraulic actuator. Only by putting the aircraft wheels on the ground, the bogie angle is forced to change.

The geometry that is needed on retraction is determined by the attitude of the gear legs in extended position, compared to the retracted position. If you look at gear legs, you will see that some are almost at right angles to the longitudinal axis, some are slanted quite a bit aft; on retraction the pivot axis may or may not be parallel to the longitudinal axis. The retraction geometry depends on where the gear support point has to be for proper balance, and where the gear has to be in retracted state, depending on space available.
Most of the times, the most efficient packing will be with the bogie beam parallel to the longitudinal axis.

Twitter n Bisted
7th Mar 2008, 05:21
EMIT
Yes, it has to do with stowing gears on retraction.

Thank you. Finally someone has stated the answer.

The one and only reason landing gear bogey tilts is so the landing assy is in the correct config to fit into the landing gear wheel well on retraction.

The orginal question :-
Could someone shed light on what the AoA of the MLG just before touch down is ?


Sorry I have read my notes cover to cover on this and I could not find the time to subtract the trailing angle of the landing gear leg from the pitch angle of the bogie then subtract this angle of pitch angle (longitudinal) of the A330 during landing phase which may (or may not) change due to prevailing conditions or pilot/autopilot in command.
Hope this helps :ok:

c130jage
7th Mar 2008, 15:12
The angle of the bogie relative to the shocker is approx 30 +/-2 degress with the shock strut at its fully extended condition.
I work for said aircraft manufacturer as a long range gear engineer.

A330AV8R
12th Mar 2008, 10:28
THats exactly what I was lookingfor , thanks a lot c130jage

:ok: