Trent_800 From United Kingdom, joined Jan 2002, 136 posts, RR: 0 Posted (13 years 3 months 5 days 14 hours ago) and read 3888 times:
On Airliners with more than two main gear legs (747,A340,A380,DC10-30) Why is there only two wheels on the Nose gear? I mean these two wheels are taking the weight of the plane from the main gear to the nose of the aircraft (that must be some weight)
Either they are super strong or they dont have much weight loading. What is the reason?
Ikarus From United Kingdom, joined Jan 2001, 3524 posts, RR: 2
Reply 1, posted (13 years 3 months 5 days 11 hours ago) and read 3860 times:
The nose gear does, in fact, take less loading than the main gear. If you imagine the plane with nose gear and main gear and centre of gravity marked, you will see that the CG is very close to the main gear. (Have a look at all the pics in the database of planes that tipped over and sit on their tails, after cargo has been unloaded properly))
If you take moments about the CG (i.e. you take times ), the Moment of the front gear has to be the same as the moment of the rear gear. As the distance is much much longer, the force is much much less. That is why less strength is needed in the front gear.
There are, of course, exceptions. Take old double-deckers or the B52 as example. Here, the moment arms are distributed differently.