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767 Main Bogies Tilt Forwards!?  
User currently offlineBA777 From United Kingdom, joined Jun 2001, 2179 posts, RR: 7
Posted (12 years 6 months 2 weeks 13 hours ago) and read 1516 times:

Guys,

Is there an explination as to why the 767s main bogies tilt forward, and the 777/747 and probably other boeing aircraft's main bogies tilt backwards?

Any reason?

BA777

15 replies: All unread, jump to last
 
User currently onlineD L X From United States of America, joined May 1999, 11454 posts, RR: 52
Reply 1, posted (12 years 6 months 2 weeks 13 hours ago) and read 1455 times:

From what I understand, the forward tilt of the 767 (as opposed to the backwards tilt or level gear of all other multiple axle aircraft) is so that the gear would fit in their housings under the plane's body.

Just a different design, really, no big deal. Think about it this way: when you jump up in the air, do you land on your toes first, or your heels first? 767s land on their toes first.



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User currently offlineRogueTrader From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 6 months 2 weeks 13 hours ago) and read 1423 times:

There was a short note about this in Airliners or somewhere several months ago. Like D L X says, it is purely a question of fitting in the gear in the best way with all the other structures in that part of the plane. Apparently, it offers no significant operational advantages or disadvantages, it is just the best way they could find to make the gear fit.

kind regards,

RogueTrader


User currently offlineAFa340-300E From France, joined May 1999, 2084 posts, RR: 26
Reply 3, posted (12 years 6 months 2 weeks 13 hours ago) and read 1390 times:

Hello,

Indeed the two main landing gears of the 767 tilt forward to fit in the fuselage between the aft cargo hold and air conditionning system.


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Alain Mengus
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User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 4, posted (12 years 6 months 2 weeks 12 hours ago) and read 1360 times:

Nope.

The 777's MLG tilt BACKWARDS when down, but tilt 5 degrees forwards when they're in the bay to fit in.

The main reason for this is due to fuselage geometry. The 767 has a tendancy to pitch forwards after touch-down. The gear tilting forwards helps to keep the nose up longer as some energy is dissipated in straightening the gear and tilting them backwards as the a/c touches down.

On the 777, for example, the gear is tilted backwards. Not only does this help smooth the landing (767 landings are always pretty hard), but it also helps to straighten the 777 out as it lands, as the straightening gear helps LOWER the nose.

It's really just a matter of design choice, there's not a lot of difference.


User currently offlineApuneger From Belgium, joined Sep 2000, 3032 posts, RR: 11
Reply 5, posted (12 years 6 months 2 weeks 12 hours ago) and read 1342 times:

A couple of years ago, I read the very same question in an aviation-related mag (can't remember which one).

Anyway, one of the experts (well, the guy who answered the reader's question) said that it (also?) has something to do with the time in which the 767 was developed (at the time the 767 was being developed, two oil crises occured). Therefore, the wing or center of gravity or whatever, was put more in front or so, hence the forward tilting bogeys.

I don't know if this makes sense, but I just try to remember what I read back then...

Ivan



Ivan Coninx - Brussels Aviation Photography
User currently offlineZebfly2 From United States of America, joined Aug 2001, 417 posts, RR: 1
Reply 6, posted (12 years 6 months 2 weeks 12 hours ago) and read 1312 times:

I can recall when I first started flying on 767's back in the late-80's, their landings did not seem to be smooth and I thought that the position of the landing gear had some thing to do with the rough landings. Now when I fly 767's the landings are much smoother. Can anyone recall the same experiences? Is it possible that over a period of time pilots became more familiar with the a/c which in turn led to smoother landings? I'm not trying to slight or question the skills of any pilots out there, but rather discussing facts that I am aware of when I first started flying on 767's. Any comments would be appreciated. Thanks.


Educate your children before others mis-educate them!!!
User currently offlineRick767 From United Kingdom, joined Jan 2000, 2662 posts, RR: 51
Reply 7, posted (12 years 6 months 2 weeks 11 hours ago) and read 1297 times:

Zebfly2,

I'm sure your experiences were just coincidental. I am not aware of any changes in the landing gear design or any other aspect which has made the 767 smoother at landing.

I find it easier to make a smooth landing in the 767 than the 757 (especially the -200, love that bird!) but then some other pilots in my company find the opposite.

From day one my landing experiences in the 767 have been the same, some days it's good, some days it's not. I haven't found myself getting better at it over the years... yet!  Smile



I used to love the smell of Jet-A in the morning...
User currently onlineD L X From United States of America, joined May 1999, 11454 posts, RR: 52
Reply 8, posted (12 years 6 months 2 weeks 11 hours ago) and read 1287 times:

Oh, one more reason for the forward tilt: so it would be easier for spotters to tell it's a 767 while still distant.

(Okay, I'm only somewhat sure the Boeing engineers thought about that.  Big grin )



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User currently offlineBlatantEcho From United States of America, joined Sep 2000, 1918 posts, RR: 1
Reply 9, posted (12 years 6 months 2 weeks 10 hours ago) and read 1240 times:

I have never heard a single one of the stories mentioned above. From what I have gathered here, and in aviation magazines (this is discussed monthly here, honestly) was rather simple.

Designing the gear, the wheels were either smaller and closer together, or the whole gear assembly was just smaller. The loading on the ground was a bit high, so they stretched out the gear a bit, maybe with bigger wheels, I don't remember. Anyway, it was very close to the end of the design phase, and with a bigger gear, they would have had to goof with the center wing box and all that jive to get it to fit. Someone figured out that a gear tilted forward would squeeze right in, so there you go.

As I said, I have garnered this information from the same question being asked 1000 times on this site, and every time the reply has been "Titled forward to fit in it's bay" nothing more or less.

I will be thrilled if there is more to it, but I'll want proof first.

regards,
BlatantEcho



They're not handing trophies out today
User currently offlineRmm From Australia, joined Feb 2001, 525 posts, RR: 1
Reply 10, posted (12 years 6 months 2 weeks 8 hours ago) and read 1209 times:

The MLG tilts 17 degrees to fit into the wheel well. It was not an after thought. What boeing didn't compensate for was the arc of the retract actuator. Our instructor told us on the first gear swing in the factory, the actuator rod ends punched holes in the upper wing skin.
If you look closely on approach (and sitting in the right row) you'll see a small door raise and lower on top of the wing while the gear is extending.

Rmm


User currently offline242 From United States of America, joined Oct 2000, 498 posts, RR: 1
Reply 11, posted (12 years 6 months 1 week 6 days 12 hours ago) and read 1128 times:

Nope.

The 777's MLG tilt BACKWARDS when down, but tilt 5 degrees forwards when they're in the bay to fit in.

The main reason for this is due to fuselage geometry. The 767 has a tendancy to pitch forwards after touch-down. The gear tilting forwards helps to keep the nose up longer as some energy is dissipated in straightening the gear and tilting them backwards as the a/c touches down.

On the 777, for example, the gear is tilted backwards. Not only does this help smooth the landing (767 landings are always pretty hard), but it also helps to straighten the 777 out as it lands, as the straightening gear helps LOWER the nose.

It's really just a matter of design choice, there's not a lot of difference.




I think that's the best explanation. The fact of the matter is that the 757, 767 and the 777 all have tilt actuators on the main gear, and all of them must tilt the gear forward upon retraction to fit them in to their gear wells. There has to be another reason for leaving the 767 mains tilted down, considering the 757 and 777 tilt them backwards during deplyment.


User currently offlineFDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 12, posted (12 years 6 months 1 week 6 days 12 hours ago) and read 1112 times:

How about the A300/A310?

The A300's are level, the A310 tilts forward.



You're only as good as your last departure.
User currently offlineHkgspotter1 From Hong Kong, joined Nov 2005, 0 posts, RR: 0
Reply 13, posted (12 years 6 months 1 week 6 days 10 hours ago) and read 1081 times:

The A340-600's main wing gear tilt back but the main center gear tilts forward !!

User currently offlineCALpilot From United States of America, joined Oct 1999, 999 posts, RR: 13
Reply 14, posted (12 years 6 months 1 week 6 days 8 hours ago) and read 1064 times:

I agree with Rick, I can usually get better landings in the B767-200. The -400 is another story for me. However, my DL buddy likes the -400 better, so go figure?

User currently offlineFlygga From , joined Dec 1969, posts, RR:
Reply 15, posted (12 years 6 months 1 week 6 days 3 hours ago) and read 1028 times:

The one that looks strange is the A340-600. The center gear tilting one way and the outer gear tilting the opposite way.

http://www.airliners.net/open.file/201681/L




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