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Can any one please explain me the basic static stability of Falcon 7x on ground at aft most CG which is 38.5%MAC=12.63498m ... because as per my hand calculations i m getting around 2% load/weight on Nose landing gear... is there something wrong with my calculations or the CG doesn't really affect the aircraft stability...?

I have used following method to determine the load

$$Fn_{min} = \frac{Bm_{min}* W}{B}$$

$Fn_{min} = 4090.817398$, % of load $2.093923332$ where $Bm_{min}$ is distance from Main Landing gear to the aft most cg = $0.201 \mathrm{m}$, $W$ is the design limit weight $=19915 \mathrm{kg}$, $B$ is the wheel base $= 9.5644 \mathrm{m}$.

enter image description here

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2% weight on nose wheel sounds plausible.

Almost all weight of an aircraft must be on the main wheels. Otherwise:

  • the elevator would have to be huge to generate enough force to lift the nose wheel off the ground on take-off and
  • on landing as the main gear contacts runway first it would create strong moment that would slam the nose into the ground.

See also Why do planes always land on rear wheels instead of the nose wheels?.

I've seen values like 4% weight on the nose wheel, so 2% for CG at aft limit makes sense. It is still enough to keep the aircraft level and leave some efficiency of the steering.

And yes, loading mistake can make an aircraft tip over on the tail:

MD-11 after loading mistake

(copied from this answer; original source)

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    $\begingroup$ I once climbed onto the tail of an RAF Hunter to spray paint a squadron zap which ended up like that. It took a few of us pulling on the nose gear to get it back down. Thankfully, the tail was over the grass at the side of a pan and damage was superficial. $\endgroup$
    – Simon
    Commented Jul 31, 2015 at 7:20
  • $\begingroup$ @JanHudec I would like to thank you for all your help and support in editing, formatting and answering my question, also wanted to request if you could share your profile details with me as I could mention you in my thesis... Thanks $\endgroup$
    – abhishek
    Commented Jul 31, 2015 at 17:35

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