Forward/aft CofG on narrow runway ops

[Pin Head]

Hi

Used to operate from a narrow runway.

Was there a benefit in non standard loading to change the CofG for better aircraft control.

I remember we used to alter it slightly when doing so.

Thanks

Pin

[John Farley]

All other things being equal a forward CG (but of course inside the allowable CG range) will give slightly more pleasant handling characteristics than an aft one as the stability in pitch and yaw will be slightly increased.

It follows that if you want to increase manoeuvrabilty (what max pitch and yaw rates you can generate) at the expense of handling characteristics you will opt for an aft CG.

Remember stability always resists any manoeuvring asked for by the pilot, but reduced stability can result in pilot overcontrol tendencies.

[BOAC]

The only effect of which I am aware is that increased loading on the nosewheel can benefit nosewheel steering, which is why 'light forward pressure' on the c column is advised, particularly in croswinds/slippery conditions.

[galaxy flyer]

The yaw component at Vmcg, as certified, is 30' deviation from centerline of the runway measures at the centerline of the plane. Narrow runways obviously mean the mains can get close to edges.

Now, Vmcg is based on the worst CG position, pretty much always aft most CG. Forward CG should make the yaw more controllable and possibly less deviation and less chance of gear going off the runway surface. Boeing does offer some performance planning with a restricted forward CG to improve runway performance by using the coward CG to reduce Vmcg. Unofficial key doing this might help but the lawyers won't be impressed.

GF

[Jwscud]

Your company may also issue specific crosswind restrictions for narrow runways, similar to the crosswind reduction required for less than fully cleared width (ours is 1kt/m less than published width) and on 30m wide runways our limit is I believe 20kt.