767 Bogeys

[Sonia767]

Hello Everyone,

Okay i know the B767 bogey tilt forwards at 17 degrees....but why ????

Heard it was so that they could fit into the wheel well.Well if that were the case then :rolleyes:

Why dont they lock horizontally once they are extended since they only needed to be tilted for retraction right :hmm:

Plus howcome most widebody jets bogeys tilt as well except the Md11 and Dc10 i think.

Wouldnt it have been easier to design the wheel well if this was the case rather than developing tilting bogeys and all the extra do dahs that go with it ???

Please dont shoot me down anybody....:ouch: only asking ;)

Sonia

[fruitloop]

Sonia
A possible answer may (and I use it carefully)could be that when the A/C was designed the use of airflow assisted extend was thought of.If you look carefully at the pivot line of the gear you will notice that it retracts slightly forward (not directly paralel)with the centreline of the aircraft)
Cheers

[gas path]

You've answered your own question Sonia. It is to ensure that the gear will fit into the wheel well.
They could be made to 'lock' horizontal but the extra 'do dahs' needed would add more weight and complication. So it's a lot simpler to have the tilt actuators just have the one action.

Do dahs......I like that:hmm:

[willbav8r]

I read somewhere that Northrop used the 76 gear for the B2 bomber?

[Sonia767]

Thanks for your replys people ;)

Pity there isnt a more complex reason for the tilt :cool:

Fruitloop i will check out the gear more closely when i fly next..

Sonia

[PlaneTruth]

Sonia,

There is also an engineering explanation (though I am not discounting the retracted storage issue).

During touchdown, the "truck" containing the four tires can either strike the ground "heel" first as does your foot or "toe" first as does the 767 and many other jets. I bet there is an engineering explanation that allows the toe-first truck to better absorb the landing impact to provide a softer touchdown. A heel strike may slap the front truck down harder exacerbating a firm touchdown.

Hispano Suiza (or their newer namesake) built most of the gears out there. Find them on the internet and shoot their engineering folks the question.

Cheers,

PT:ok:

[Sonia767]

Planetruth hello,

Your explanantion sounds right as well i think.

I was also thinking :) (yeah right)

Does the tilted wheels actually give a greater clearance on landing than if the wheels were horizontal ??? Would make sense on the 767 but dont know about A330 etc

Dont know if you can picture what i mean but with the wheels tilted you touchdown earlier than if the were horizontal.

Ok maybe im making this all up :hmm:

But could this be a reason

Sonia

[PlaneTruth]

Sonia,

You are exactly right.

As you stated, the bogey or truck tilts down 17 degrees when deployed in level flight. In the flare, your 767 is about 3-5 degrees nose up (for the discussion we'll pick 4 degrees).

That means the front wheels on the bogey are 13 degrees down when you are flaring 4 degrees nose up. Evidently the engineers want those wheels to touchdown first. If you peek at your gear, you may find a damper (shock absorber) that takes up some of the force of rotation as the bogey tries to slam the back wheels on the runway. Or, it may well be the act of landing the rear tires after the first takes some of the impact away from the landing. Either way, it is clearly by design.

Cheers!

PT

[ironbutt57]

They hang opposite the 757 and most other planes, coz there wern't no room to fit them otherwise due to the configuration of the wing..'coording to a boeing tech rep who said that is "the most asked question by pilots of the 767" the shock absorber is a "truck tilt actuator" according to the same gentleman can be placed on smoothly with no "slapping" but requires more technique than the 757 for sure:cool:

[PlaneTruth]

Ironbutt,

There you go! I knew SOMEONE out there had asked the manufacturer. I bet Sonia will tell us the hydraulic plumbing in the wheel well is situated in the back of the wheel. And I'd wager that the 757 is just the opposite. Any 75 pukes out there with the answer?

I guess the trick is to land the front truck smoothly and as the boards come up the aircraft settles on the rear truck in one fluid motion.

I bet Sonia does this with effortless regularity.


PT:p

[ironbutt57]

757 not as much wing sweep, and if I remember correctly, yes the hyd reserviors are in the fwd wheel well..correct me if i'm wrong..

[BAe 146-100]

Hi,

767 Pilots, do you find the 767 more difficult to land then other aircraft?

Regards :D
BAe 146-100

[Sonia767]

Thks again people for your responses.

Clever bunch of people you are out there :cool:

I bet Sonia does this with effortless regularity.

Very funny Planetruth

Regularly maybe but not effortlessly ;)

Safe flying everyone

Sonia

[Pilot Pete]

Bae 146-100

Tell you tomorrow as I have my first line sector on the 76 after conversion from the 75.:\

PP

[shuttlebus]

I remember reading an answer to this question in an Airlners World (or similar) magazine about 5 or 6 years ago. The exact details have got lost in the mists of time but the main points were something along the lines of...

"... The bogies hang forward do that the wheels are parallel to the main spine (fore/aft beams of the aircraft structure) beams when the gear retracts. The main reason for this was during the design of the 767, there was a large increase in the price of oil (Middle East oil crisis, I believe). Therefore, the wing design was changed (sweep increased and moved slightly further back on the fuselage to improve fuel efficiency) As a result, the bogies then needed to tilt forward so that the wheels were parallel with above mentioned spine beam. (Something to do with reducing redesign....?)

Hope this helps. As I put in above, I am dragging this out from the "totally useless things to remember" bit of my brain, so apologies in advance for any errors.

Regards,

Shuttlebus

[Pilot Pete]

Bae 146-100

Happy to report back no more difficult than the 757. Flew the -300 today and what you really notice is the extra inertia due to the extra weight. I certainly felt the truck tilt when PNF which feels different to the 757, but did not feel it on my own landing........not because it was any better, probably just down to me working a lot harder as PF and not having as much capacity to notice these 'minor things'!

Other noteable differences are the number of seats down the back(!) the step 'up' into the flight deck as opposed to the step down into the 75, carpets on the FD floor (no sh*t!) and the way it handles; much lighter in the rotate, but significantly heavier in pitch when flying, also much more stable in roll, very serene and a pleasure to fly. The inertia already mentioned requires more anticipation, ie. if you get a couple of knots slow on approach you need to catch it quicker or you end up having to put handfuls of power on to claw the speed back, so as ever with a big jet it's better to anticipate early and correct any trend away from that desired.

PP