Slanting direction of the main landing gear?

Question

I've been wondering why some main landing gears slant forward or backward. For example, a Boeing 767 has its wheels slanting forward (as in the front end of the gear makes contact with the ground first); on the other hand, an Airbus A330 has its wheels slanting backward (as in the back end of the gear makes contact with the ground first).

Is there a reason for this? For me, the A330's landing gear seems to look more sensible because it causes the aircraft to gently lower itself onto the front half of the main gear; however, the 767 has its main gear sort of 'slaps' itself onto the runway.

Answer 1

Just guessing I would say it is the weight distribution of the basic operating weight.  (i.e. the plane with nothing on it)  When we load cargo on planes the weight distribution between say a Boeing 727 and an Airbus 310 are totally different.  Where you can put more weight versus if the plane is nose heavy or tail heavy vary widely with planes due to how they are built.  For instance we had to tether an airbus's nose to the ground because it is tail heavy and would readily tip over as we loaded if we didn't.  So I would say the build of the plane and how that weight is distributed would have everything to do with the slant of the landing gear.  Like a DC-10-10 vs. a DC-10-30.  They are close to the same plane weight wise.  Close but not exact because the 30 has to have an extra set of landing gear in the rear.  So while loading the plane it looks the same but standing outside it one has two rear landing gear and the other three.  Weight distribution would be my guess.  =)

Answer 2

I have to say I'm not SURE about my answer.

The 767 (after looking at a few pictures,) has wheels that tip forward on approach, but during the flare portion of the landing, they would be FLAT to the runway. The flare portion is where the position of the wheels is important. I suspect this is to ensure that as much rubber as possible is touching the ground at once during the landing.

on a 747 however, there are not only two main gear (pods?) there are four. (sixteen wheels.) The main gear on the 747 actually turn as though on castors, so in a severe crosswind, they just fly the plane onto the runway sideways, and the wheels turn. I believe that's why the back wheels are lower than the front... to make the gear turn BEFORE there's a lot of rubber on the road.

( I know this about landing the 747 because I had an FAA examiner give me an earful in the 747 simulator when we were playing with 35 knot crosswinds.)

If someone knows better I'd really like to learn more!

Answer 3

Its just a matter of design. It has to be slanting in a way to ensure those set of wheels touches first before the other does.

Answer 4

I think you are referring to the slant of the main wheels axle of the main landing gear not the landing gear itself. Although most landing gears are designed  a little slanted for rigidity purposes but here you are talking about the tire position as they land, this is because of the boogie beam which tilt the main wheel axle so that the rear wheel touches first the ground or the front tire first. B747 rear tires touches first, are you sure 'bout the 767 touching front first?

As for the reason I know it has but too lazy to read my training manuals & besides the 10 points seems illusive to me this past days even though I give  good answers.