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SoundBarrier
16th Apr 2008, 01:58
Reading a recent post on the clunk type noises heard during taxi it rekindled a question I have about the bogies on the big jets...

My trusty 182 turns on the ground by directional manipulation of the nosewheel. Easy stuff. Landing in a crosswind I land on one of the mains first, then the second and finally the nosewheel. (If I'm doing a crosswind on a good day).

Doing said manouevre (sp?) in a 777 for example, would put a substantial amount of pressure on the one bogie which it can obviously take cos I have seen it happen (albeit gently done). My question is, though, do the main bogies turn as well, and if so how is their direction controlled? Are they turned during the taxi as well?

Old Fella
16th Apr 2008, 03:22
Hi Sound Barrier. Can't comment on the B777 which has two triple axle main undercarriage trucks (total 12 main landing gear wheels) and I seem to recall reading that these are steerable to relieve loads on the inside truck in turns, but would certainly be locked in the "straight ahead" position for take-off and landing. The B747, which has four two axle main landing gear trucks (total 16 main gear wheels) of which two are body mounted gear and the other two are wing mounted. The body gear are able to be steered in turns to relieve stress, however the wing gear do not. The body gear are locked in the "straight ahead" position for take-off and landing. As for landing on "into wind" main gears first in X-wind conditions this is normal practice and is easily handled by the main landing gear assemblies. On an aircraft such as the B52, to assist in X-wind landings the aircraft can be landed with a fair degree of drift on, as the landing gear is able to be offset to align with the runway, even though longitudinally the aircraft is not. Nose wheel steering in large aircraft is often linked to the rudder system "Rudder fine steering" for ease of taxying and for larger correstions the "tiller" or nose gear steering wheel is used. Hope this is helpful. Happy landings. :ok:

Engineer_aus
16th Apr 2008, 09:06
The 777 has the rear axle which is steerable to eleviate stress on the gear structure