Mass & Balance calculation

[Founder]

Dont really know if it's the right place to post this question but anyway.

How do you calculate a question like this one:
An aeroplane with a two wheel nose gear and four main wheels rests on the ground with a single nosewheel load of 725 kg and a single main wheel load of 6000 kg. The distance between the nose wheels and main wheels is 10 meters. How far is the CG in front of the main wheels?

Do I double the 725 kg load, and take 4 times 6000 kg?

The answer should be 0,57 meters.
Does anyone know?

[john_tullamarine]

.. think you got it in one ..

(a) nose = single axle two wheels = 725 x 2 = 1450 kg

(b) mains = (single axle two wheels) x 2 = 6000 x 4 = 24000 kg

Taking moments about the mains ..

M = - ( 1450 x 10 ) kg.m

= - 14500 kg.m

CG = total moment/total weight

= - 14500 / (24000 + 1450)

= - 0.57 m

(ie 57 cm in front of the main axle line)

.. unless, of course, it's getting a bit late in the day and I've made a mistake ...

[Founder]

I did in fact figure out the calculation my self but you calculated it in a much easier way =)

Thank you =)