morrisond wrote:We are talking about a difference of less than 1% in MTOW due to a wider fuselage

Yes, the increase in the fuselage weight is less than 1% of MTOW, the other weight increases however add up to a significant amount and you have negated to show those?

morrisond wrote: It is probably assuming that due to the Wider wingspan or wider fuselage the engines are farther apart, which leads to a bigger tail which leads to more weight which leads to wider wingspan, more thrust, more weight in an endless loop.

there are many potential reasons, the optimisation may have shown that it was better to have a bigger surface rather than a heavier double articulated rudder mechanism.

morrisond wrote:However assuming they are trying to fit a 6W or 7W into the same gates and that the same amount of Wing that can be hinged the wingspan has to be held constant. He is assuming a 41M wing on 6W that I am assuming is about the maximum that could fold down to 36M.

Incorrect, the wing geometries were held with equal AR and equal wing loading at MTOW, this dictated the wingspan.

morrisond wrote:offset by possibly more lift off the wider flatter body.

What? Still on with the body lift. Can you show it?

morrisond wrote:And of course shorter/lighter gear - especially if it is closer spaced due to the shorter fuselage length.

Shorter gear? Do you want me to re run the analysis compensating fort he Higher SFC due to needing lower bypass ratio for the lower gear required?

morrisond wrote:As I keep saying the math is complicated. Airliner design is complex and there are many tradeoff's to be made in many areas.

No, the maths is not complicated. At all.

morrisond wrote:Fred calculated it's only 1,000KG

In the fuselage, for the aircraft with the significantly wider aisle....

Wing is 1998kg heavier

Horizontal tail is 701kg heavier

Vertical tail is 369kg heavier

Fuselage is 1010kg heavier

Gear is 400kg heavier

Control weight is 668kg heavier

Hydraulics and pnue is 63kg heavier

morrisond wrote:and that's with adding a bunch of extra weight in.

I have added no extra weight. Please redact that statement or I shall have your post reported.

morrisond wrote:tight light 7W

Trope Much?

morrisond wrote: is probably making the same sort of calculations as it goes about it's merry way saying if this is bigger then that has to be bigger.

No, I have explained this previously, the two compared models to which you refer and that I have done the analysis for have the horizontal tail which scale comparatively with the ratio of lengths and ratio of wing areas and the vertical tail scales with the ratio of thrust, the ratio of length and the ratio of wingspan. This assumes that a constant pressure differential (Cl) is maintained by the vertical and horizontal tail surfaces.

Like I say Morrisond please remedy the areas where you have part quoted me out of context or I will be forced to report the offending posts and have them deleted. Is that clear?

Fred