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Rear Bogies Steering!

EK413 From Australia, joined Nov 2003, 3983 posts, RR: 4
Posted (7 years 2 weeks 1 day 22 hours ago) and read 1987 times:

Hey A.Netter's! Big grin

I came across this pretty cool snap shot of United Airlines B747-422 N175UA taxiing out for departure....If you have a really close look at the rear bogie's they seem to be turning in another direction as opposed to what the aircraft is heading! I'm aware of the US bound flights departing to maximum weight but wasn't aware that it was to this extent!

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Photo © JumboJim747

Enjoy!!! Big grin

EK413

Qantas and Emirates, connecting the globe 1 stop to 65 destinations

14 replies: All unread, jump to last

StealthZ From Australia, joined Feb 2005, 5448 posts, RR: 48
Reply 1, posted (7 years 2 weeks 1 day 21 hours ago) and read 1960 times:

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EK413,

The weight has nothing to do with it, that aircraft is turning on to Sydney's RWY25 and is operating flight UA839 SYD-MEL which is almost as short and light as a 747 flight gets. The turn from Twy Golf on to the runway is quite tight though.

See...

Steering Of MLG Bogies (by JumboJim747 Jun 6 2006 in Tech Ops)

cheers

If your camera sends text messages, that could explain why your photos are rubbish!

UA772IAD From Australia, joined Jul 2004, 1639 posts, RR: 3
Reply 2, posted (7 years 2 weeks 1 day 21 hours ago) and read 1949 times:

The answer is quite simple really, and has nothing to do with weight. The MLG bogies turn in the opposite direction to swing the back end of the plane out, just a little more, so the pilot doesn't have to make as wide of a turn, especially in during tight maneuvers. It's kind of like the counter steering you see the trailer driver of a large rig fire truck.

Boeing Nut From , joined Dec 1969, posts, RR:
Reply 3, posted (7 years 2 weeks 1 day 13 hours ago) and read 1812 times:

Quoting UA772IAD (Reply 2):
The answer is quite simple really, and has nothing to do with weight. The MLG bogies turn in the opposite direction to swing the back end of the plane out, just a little more, so the pilot doesn't have to make as wide of a turn, especially in during tight maneuvers. It's kind of like the counter steering you see the trailer driver of a large rig fire truck.

Almost right. The whole design reasoning for the steerable main bogies is to save tearing up the tires and pavement during a phenomenon known as "tire scrub". Saves stress on the gear itself as well.

Regards

777DadandJr From United States of America, joined Feb 2005, 1516 posts, RR: 12
Reply 4, posted (7 years 2 weeks 1 day 13 hours ago) and read 1767 times:

Quoting UA772IAD (Reply 2):
The answer is quite simple really, and has nothing to do with weight.

Quoting Boeing Nut (Reply 3):
Almost right. The whole design reasoning for the steerable main bogies is to save tearing up the tires and pavement during a phenomenon known as "tire scrub". Saves stress on the gear itself as well.

To add,
It is my understanding that the MLG steering doesn't come into play unless the nose gear is turn more than 20 degrees. I beleive that is what is in one of the books I have at home.

Russ

My glass is neither 1/2 empty nor 1/2 full, rather, the glass itself is twice as big as it should be.

EK413 From Australia, joined Nov 2003, 3983 posts, RR: 4
Reply 5, posted (7 years 2 weeks 1 day 12 hours ago) and read 1736 times:

Cheers guys! Big grin

I did question where this flight was bound & now that it has been brought to my attention this definately is a runway 25 departure...
Cheers once again! Big grin

EK413

Qantas and Emirates, connecting the globe 1 stop to 65 destinations

OB1504 From United States of America, joined Jul 2004, 2975 posts, RR: 8
Reply 6, posted (7 years 2 weeks 1 day 12 hours ago) and read 1707 times:

The 777 also has this form of steering. The photos don't show it well, but they're the closest I could find in about 1000 shots.

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Photo © Fabian Gysel

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Photo © John Harris

JBirdAV8r From United States of America, joined Jun 2001, 4459 posts, RR: 22
Reply 7, posted (7 years 2 weeks 1 day 11 hours ago) and read 1624 times:

Quoting OB1504 (Reply 6):
The 777 also has this form of steering. The photos don't show it well, but they're the closest I could find in about 1000 shots.

The aft two wheels of each main landing gear assembly are steerable on the 777.

I got my head checked--by a jumbo jet

BandA From United States of America, joined Aug 2004, 336 posts, RR: 0
Reply 8, posted (7 years 2 weeks 1 day 9 hours ago) and read 1536 times:

Quoting 777DadandJr (Reply 4):
Quoting UA772IAD (Reply 2):
The answer is quite simple really, and has nothing to do with weight.

Quoting Boeing Nut (Reply 3):
Almost right. The whole design reasoning for the steerable main bogies is to save tearing up the tires and pavement during a phenomenon known as "tire scrub". Saves stress on the gear itself as well.

To add,
It is my understanding that the MLG steering doesn't come into play unless the nose gear is turn more than 20 degrees. I beleive that is what is in one of the books I have at home.

Russ

wow, this is something I never knew... the main land gears actually can steer, is this pretty much standard on large aircraft or an option?

"They [Terrorists] never stop thinking about new ways to harm our country and our people, and neither do we." - GWB

777DadandJr From United States of America, joined Feb 2005, 1516 posts, RR: 12
Reply 9, posted (7 years 2 weeks 1 day 9 hours ago) and read 1506 times:

Quoting BandA (Reply 8):
wow, this is something I never knew... the main land gears actually can steer, is this pretty much standard on large aircraft or an option?

According to the book that I have at home, and my apologies for not referencing it (I am at the office) shows that the 747 and 777 has this feature from the start.

Russ

My glass is neither 1/2 empty nor 1/2 full, rather, the glass itself is twice as big as it should be.

JBo From Sweden, joined Jan 2005, 2281 posts, RR: 0
Reply 10, posted (7 years 2 weeks 1 day 9 hours ago) and read 1506 times:

The C-5 does this as well:

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I'd take the awe of understanding over the awe of ignorance any day.

Tristarsteve From Sweden, joined Nov 2005, 3713 posts, RR: 34
Reply 11, posted (7 years 2 weeks 1 day 8 hours ago) and read 1475 times:

Quoting OB1504 (Reply 6):
The 777 also has this form of steering. The photos don't show it well,

I don't think you will see it in a photo. I do push backs on B777 and we go round a 90deg turn onto the taxiway. I was watching from the tug and could not see the rear wheels steering. I know they do because when you sit in the flight deck for a tow you can see them turning on the maint pages.

777DadandJr From United States of America, joined Feb 2005, 1516 posts, RR: 12
Reply 12, posted (7 years 2 weeks 1 day 8 hours ago) and read 1453 times:

I believe that the AN-225 has steering on it's MLG.(though I have yet to find a picture of it)

Russ

My glass is neither 1/2 empty nor 1/2 full, rather, the glass itself is twice as big as it should be.

AsstChiefMark From , joined Dec 1969, posts, RR:
Reply 13, posted (7 years 2 weeks 1 day 7 hours ago) and read 1390 times:

A B-52 can crab its way down a taxiway. It's the goofiest thing I've ever seen. An airplane taxiing diagonally.

Mark

UA772IAD From Australia, joined Jul 2004, 1639 posts, RR: 3
Reply 14, posted (7 years 2 weeks 21 hours ago) and read 1240 times:

Quoting EK413 (Reply 5):
Cheers guys!
I did question where this flight was bound & now that it has been brought to my attention this definately is a runway 25 departure...
Cheers once again

You learn something new here everyday. Check out this article for more on taxiing those behemoths:

http://www.usatoday.com/travel/colum...e/2005-07-18-ask-the-captain_x.htm

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