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Faro
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A330 Main Gear Bogey Tilt

Sun Sep 11, 2011 10:34 am

The A330 main gear bogies exhibit a very marked backward tilt on extension. In neighbouring A.net threads, bogey tilt in general was explained as being necessary to facilitate the retraction of the bogies into the wheel wells or to soften landings.

On the A330 however, the wheel wells are parallel to the fuselage and there doesn't seem to be an appreciable softening of landings by the bogies on videos of A330 landings. Is it to provide a cautionary soft 'detent' against tailstrikes or for some other reason? The tilt does seem to be rather extreme and doesn't help the aircraft's drag in the landing configuration...

Faro

PS: Does automatic ground spoilers deployment activate with rear bogey or front bogey impact? This is not too clear on video shots.
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Starlionblue
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RE: A330 Main Gear Bogey Tilt

Sun Sep 11, 2011 11:45 am

Maybe the weight bias around the axis at the bottom of the strut makes them tilt like that, meaning the designers wanted the rear axle to hit first.

Quoting faro (Thread starter):
The tilt does seem to be rather extreme and doesn't help the aircraft's drag in the landing configuration...

I think the extra drag is probably negligible in the context of the gear in general. Not to mention flaps and slats.

Quoting faro (Thread starter):
Does automatic ground spoilers deployment activate with rear bogey or front bogey impact? T

Pretty sure armed spoilers deploy when the strut for the main gear compresses. If one or both main struts I don't know.

The nose gear has no bogey. It's just a single axle unit with two wheels.

Quoting faro (Thread starter):
there doesn't seem to be an appreciable softening of landings by the bogies on videos of A330 landings.

You wouldn't be able to tell from a video.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
mandala499
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RE: A330 Main Gear Bogey Tilt

Sun Sep 11, 2011 12:22 pm

Quoting Starlionblue (Reply 1):
Pretty sure armed spoilers deploy when the strut for the main gear compresses. If one or both main struts I don't know.

Both Main Gear compressed and RA less than 6ft...
And...
If GNDSPLR is unarmed, at least 1 Thrust Lever in reverse and the other lever at idle (ie: if both in reverse, it would deploy)
or
If GNDSPLR is armed, both levers at idle or less.

If only 1 MLG compressed, and RA is less than 6ft and at least 1 Thrust Lever in reverse and the other lever at idle or lower, it would partially deploy as long as this condition remain valid.

Mandala499
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my235
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RE: A330 Main Gear Bogey Tilt

Sun Sep 11, 2011 7:48 pm

IMHO A330's have the softest landing of any airliner due to the added length of the landing gear. The 747 also has about the same angle of tilt on two of it's four rear bogies. I think the design was to have the gear contact the runway with the aircraft still at the top of ground effect.
 
N243NW
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RE: A330 Main Gear Bogey Tilt

Sun Sep 11, 2011 8:45 pm

One of the interesting things is the noticeable pitch forward that the pilots command (or the aircraft exhibits) after the rear axle hits on the A330 and A340. Can someone shed some light on this? Is it a technique to help get the whole truck on the ground and the spoilers out or is it a phenomenon that simply results from the geometry of the gear?

Also, to those who fly (or fly on) the 330: I would make the assumption that the part of the landing that is "felt" the most is the front axles coming down...am I correct? It seems that the rear axles would create a light shudder inside the cabin and the main thump would come from the rest of the truck hitting the ground.
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my235
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RE: A330 Main Gear Bogey Tilt

Mon Sep 12, 2011 2:33 am

Quoting N243NW (Reply 4):
It seems that the rear axles would create a light shudder inside the cabin and the main thump would come from the rest of the truck hitting the ground.

You are so right. I've flown on A333/343 a number of times. Almost every landing was how you described. Smooth as silk.

http://youtu.be/lowrM-780tg
 
imiakhtar
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RE: A330 Main Gear Bogey Tilt

Mon Sep 12, 2011 3:40 pm

Quoting N243NW (Reply 4):
One of the interesting things is the noticeable pitch forward that the pilots command (or the aircraft exhibits) after the rear axle hits on the A330 and A340. Can someone shed some light on this? Is it a technique to help get the whole truck on the ground and the spoilers out or is it a phenomenon that simply results from the geometry of the gear?

Not sure about the A340 but the recommended technique on the A330 is to ease off on the back pressure and relax the side-stick towards the neutral position when you feel the rear wheels touchdown and let the aircraft de-rotate naturally. Once the whole main gear is down you "fly" the nose down - otherwise you risk a hard nose gear touchdown like the Royal Air Maroc 767 at JFK a few years ago. The whole idea is to get weight on wheels and maximise the braking effort.

Quoting my235 (Reply 5):
Smooth as silk.

http://youtu.be/lowrM-780tg

That wasn't very smooth on the nose gear!
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shufflemoomin
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RE: A330 Main Gear Bogey Tilt

Mon Sep 12, 2011 3:57 pm

Quoting my235 (Reply 3):
IMHO A330's have the softest landing of any airliner due to the added length of the landing gear

When my SAS A330 landed in EWR in January it was the hardest landing I've ever felt followed by the hardest braking I've experienced too. My iPad bounced of the seat and thanks to the braking ended up about 2 or 3 rows in front. I guess it all really comes down to the guys up front.
 
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Starlionblue
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RE: A330 Main Gear Bogey Tilt

Mon Sep 12, 2011 5:11 pm

Quoting shufflemoomin (Reply 7):

When my SAS A330 landed in EWR in January it was the hardest landing I've ever felt followed by the hardest braking I've experienced too. My iPad bounced of the seat and thanks to the braking ended up about 2 or 3 rows in front. I guess it all really comes down to the guys up front.

You can't draw any conclusions from one landing. Any number of special circumstances that the guys in front had no control over may have been in effect.

Note also that pilots are not paid to perform smooth landings. They are paid to perform safe landings.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
N243NW
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RE: A330 Main Gear Bogey Tilt

Mon Sep 12, 2011 6:28 pm

Quoting imiakhtar (Reply 6):
That wasn't very smooth on the nose gear!

At that point the PF was starting to realize that his "smooth as silk" touchdown had used up 3-4k feet of runway and he better get the nose down and start slowing  
B-52s don't take off. They scare the ground away.
 
Max Q
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RE: A330 Main Gear Bogey Tilt

Tue Sep 13, 2011 6:17 am

Quoting N243NW (Reply 9):

At that point the PF was starting to realize that his "smooth as silk" touchdown had used up 3-4k feet of runway and he better get the nose down and start slowing

No, when the nose gear finally touched down, he had completely run out of elevator authority, if you look closely you will see it is deflected fully up.



In other words, it was coming down no matter what the Pilot did !
The best contribution to safety is a competent Pilot.
 
N243NW
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RE: A330 Main Gear Bogey Tilt

Tue Sep 13, 2011 6:42 am

Quoting Max Q (Reply 10):
No, when the nose gear finally touched down, he had completely run out of elevator authority, if you look closely you will see it is deflected fully up.

Ahh, so I see the crew was practicing their soft field technique then!  
B-52s don't take off. They scare the ground away.
 
Max Q
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RE: A330 Main Gear Bogey Tilt

Tue Sep 13, 2011 7:11 am

Quoting N243NW (Reply 11):

Ahh, so I see the crew was practicing their soft field technique then

Not something to practice in a widebody Jet Transport.
The best contribution to safety is a competent Pilot.
 
N243NW
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RE: A330 Main Gear Bogey Tilt

Wed Sep 14, 2011 6:43 pm

Quoting Max Q (Reply 12):
Not something to practice in a widebody Jet Transport.

The reason why I added the smiley...
B-52s don't take off. They scare the ground away.
 
hal9213
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RE: A330 Main Gear Bogey Tilt

Fri Sep 16, 2011 1:59 pm

Quoting my235 (Reply 3):
IMHO A330's have the softest landing of any airliner due to the added length of the landing gear.

Weird, I always get bumpy touchdowns on my trips. But this definately mostly depends on a whole lot of other factors.
I love the 777 landings, on some smooth ones, you can actually feel the triple-bogey, like thumb-thumb-thumb followed by the springy strut compression.
 
Airbus_A340
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RE: A330 Main Gear Bogey Tilt

Sat Sep 17, 2011 8:47 am

As most posters above have observed and posted, you can experience a smooth touchdown on the rear-bogies but then it is very unforgiving when the rest of the bogie comes into contact with the ground.

Deceleration of the aircraft increases the hardness of the landing as the aircraft slows and "falls" onto the rest of the bogie. As imiakhtar has said, the recommended technique is to neutralise the controls for derotation. Having said that, there are some "tricks" to soften the second touchdown. After rear bogie touchdown inputting forward sidestick input to assist the derotation. A second "trick" is to delay pulling thrust reversers, again delaying the deceleration. Having said that, i stress that this is not a recommended technique, though you will find many people on the line utilising these techniques on non-field length limited runways to smoothen the landings. The techniques I described may be noticed in some videos that can be found on yourtube.

hope that helps
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my235
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RE: A330 Main Gear Bogey Tilt

Wed Sep 28, 2011 1:30 am

Quoting hal9213 (Reply 14):
I love the 777 landings, on some smooth ones, you can actually feel the triple-bogey, like thumb-thumb-thumb followed by the springy strut compression.

A+  
 
flyingcello
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RE: A330 Main Gear Bogey Tilt

Thu Oct 06, 2011 7:37 pm

The A330 is well known for having a low wing loading...at low weights, descent planning is supposed to be key, as the beast just doesn't want to descend! Is this one possible reason why the landings are 'soft'?

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