Boeing Landing Gear Question

[2000flyer]

Ok you aeronautical buffs (or engineers, you choose). Sitting in a VERY long line at KORD today, I watched several aircraft coming and going while waiting. Something, don't ask me why, struck me as interesting (or maybe I was just dying to get airborne after a 55 minute taxi).

A 757 main landing gear trucks have a slight positive angle (front tire higher than rear tires on main trucks). However, the 767 gear has a larger negative angle. The 777 has an even larger positive angle.

Can anybody tell me why this is?

Just curious, thats all.

Regards,
2000Flyer

 

[SkyWestCRJPilot]

The 747 also has a negative angle. I too would love to know the answer to this.

 

[mach none]

The reason for the 747 wheel tilt is so the wheels will fit in the wheel wells. There are indicator lights on the FE panel confirming "tilt."

 

[Jet_Dreamer]

i have been told these angles to the main landing gears assist in braking performance. any truth to this?

 

[mainah]

Not the 757 or 767 but I hope this helps. According to the 747-400 Systems guide from Boeing, all main gears are tilted to reduce the space the gear takes up in the stowed condition and to provide air and ground sensing. The wing gear tilts 52 degrees and the body gear tilts 7 degrees.

 

[jdog78]

I read that the odd tilt of the 767 bogies was required after the design process because the gear wouldn't fit into the well. So instead of redesigning the well, the strut was mounted at an angle and an actuator was fitted to tilt the bogie down, thereby allowing the wheels to fit.
I have also read that hanging the gear at an angle helps soften the impact of touchdown. The VC-10 was supposedly infamous for its soft landings, due in whole or in part to the slight upward tilt of the bogies.
In any case, I'm strangely drawn to tilted bogies...especially the 767. Hmm....

-j

 

[Iceman21]

(or maybe I was just dying to get airborne after a 55 minute taxi).

55 minute taxi? What runway did you depart from? 32L from T-10 isn't that far of a taxi from Signature. Unless they had you taking off of 9L or 4L than it could be fun in that configuration.

I can't imagine ORD having that bad of delays for a day like today. On a nice snowy night in December I can understand.

Actually, I heard there was something going down over there this afternoon, but the guy I talked to wouldn't open his mouth any father than that.

 

[2000flyer]

Re: Re: Boeing Landing Gear Question

55 minute taxi? What runway did you depart from? 32L from T-10 isn't that far of a taxi from Signature. Unless they had you taking off of 9L or 4L than it could be fun in that configuration.

We started at the new Signature. Took nearly 15 minutes for ground metering to get to us due to volume. Originally told to expect 27R for departure. By the time we got to txwy V1, told to plan on 32R. Two planes in front of us departed on 32R, then they switched runways to depart to the east, so we were turned to cross the approach end of 27R, then down the long line for 9L. Due to the runway change, there were probably close to 30-40 aircraft in line that were also affected by the runway change.

I still contend that ORD controllers are the best in the world. No one can move aircraft around on the ground or in the terminal area like the fine folks at O'Hare / Chicago Approach.

IMHO of course.

As for the landing gear question originally posted, thanks for the input. It makes sense that it's a storage design more than a landing design.

Regards,
2000Flyer

 

[Iceman21]

Re: Re: Re: Boeing Landing Gear Question

I still contend that ORD controllers are the best in the world. No one can move aircraft around on the ground or in the terminal area like the fine folks at O'Hare / Chicago Approach.

That's right I forgot about the fact that they moved accross the field after I left. Some of my fondest memories there was watching and listening to the ground controllers fix the Charlie Foxtrot's that LGA or ENW would cause with ground stops all while I had 30 RJ's and Brasilla's sitting waiting to exit the alley. Great bunch of folks there....if you do what you are told and not what you want to do.

 

[Lancair]

Delays

We had the same problem at ORD yesturday as well. First Ground took 15 minutes to get a hold of us. Then they sent us to 22L. From there they decided to send us to 9R for a runway swap. Of course we had no data for 9R. But the line was long and thank god for ACARS. Then the decided that wasn't going to happen and moved the entire line of us to 9L. In all it took about 50 minutes to get out of there. You do have to give the controllers credit for how well they moved such a large amount of aircraft. Besides I get paid by the hour.