Steerable main undercarrage on 747?

[Snow]

I downloaded the MelJet 747-400 for flight simulator 2002, it's a fantasticly detailed aircraft and if you like FSing and large planes, I highly recomend it.

Anyhow, I notieced in tight turns the 2 inside main undercarrage wheel assemblies roated in the oppsite dirrection to the nose gear, (kinda like that 4 wheels steering that Honda has) to produce a sharper turn. I can't say I've ever seen this on a real 747 before, (although most of the 747 taxing action I see is from in the cabin just wondering if anyone can confim if this is a real feature on the 744s.

Thanks,

[pscraig]

Yes, I believe the real 747s do have steerable gear. However, I think it is for landing in a crab, not sure if it can be used to reduce a turn radius on the ground.

[Baronman]

Not sure about that one...

I know the 777 has limited steering in the main wheels for taxiing.

[A300Capt]

From talking with some of our 747 crews, the two inner (inside) main gear wheels do turn as you describe to help during tight taxiing situations. The gear, unlike that on a B-52, does not turn while airborne to help during x-wind landings.

[mikek123]

I just finished a class at Riddle on the systems of the 747 and yes the 2 body gear do allow steering at speeds of up to 15 Anytime the nose wheel is beyond 20 degrees at less than 15 knots the body gear will turn opposite the nose wheel to tighten the turn. When the ground speed increases to above 20 knots the body gear are automatically centered and body gear steering is deactivated.

[Snow]

Cool thanks for the info guys! You learn somthing new everyday. I've been looking at the Boeing webpage and the 747 is truely an amazing aircraft. Looks like it will be around for several more decades too considering the 747-400 has been around since 1989 with 550 examples flying today and there is currently 650 more on order by over 40 different airlines!

As someone mentioned the crab landings, I've heard that Boeing has testing landings at crab angles of upto 45deg without any damage to the aircraft! (Those of you who don't know the 747 can only bank 5deg on landing because of the long wings / low engines) Just have a look at Airliners.net there's some insane looking 30deg crab landing pics of 747s on there, not to mention a few engine strikes too! Have a look at the old Hong Kong airport pics in particular.

[I_Money]

Snow, do you remember the Qantas 747 which had a gear collapse, when it made a sharp turn. It was a few years ago, I am sure you can find some info on it if you run a search.

[seagull]

There is a switch on the overhead to arm bodygear steering, it is not automatic.