Design parameters and ride quality

[whitespiral]

I was curious what factors the multiple type-ratings types here have found to be of most importance on an aircraft's ride quality. Which, by experience would you say are by far the biggest contributors or combinations of contributors?

-Sheer size?
-Weight?
-Inherent maneuverability/Design instability?
-Wing loading?
-Approach speeds? (for low level turbulence)
-Cruise speeds?
-Cruise FLs/Operating ceilings?

[formulaben]

My 2 cents:

-Sheer size?
For vertical turbulence, not a factor in itself, wing loading and wing design is. But a larger aircraft with more inertia will probably take smaller lateral or rolling gusts much better when landing.

-Weight?
Not really a factor, except that for each airplane type, it will tend to fly better (RIDE-WISE, not performance-wise) at max gross versus lower weights.

-Inherent maneuverability/Design instability?
These can have an effect, e.g. an aircraft with too much dihedral.

-Wing loading?
This has a huge effect on how an airplane rides through turbulence.

-Approach speeds? (for low level turbulence)
I would guess is a non issue, as wing loading (besides weight, wing design, etc.) dictates the approach speeds...

-Cruise speeds?
Goes back to wing loading and available thrust, but for a given airplane, the higher speeds will create higher G loading. A non-issue if turbulence dictates speed reductions to Va.

-Cruise FLs/Operating ceilings?
An airplane that can cruise high above the weather will no doubt give you a much better ride than one in the high 20s/low-mid 30s, but this has nothing to do with the wing.

I would add that regarding wing design, straight-wing aircraft such as the Cessna 500 series have a relatively harsh ride compared to swept wing aircraft, and of those, some have even more flexibility (for lack of a better word) built into the wing. For example, the IAI-1125/G-100 has a fairly soft ride in part to the wing sweep and because the wings tend to flap up and down in turbulence. The 777 even more so. On a side note, some models of Airbus have GLAS: gust load alleviation system, in which a computer raises the spoilers during positive G gusts in an attempt to equalize the excess lift.

[whitespiral]

FormulaBen,


Thank you for your insight. Doesn't more "flexibility" however bring the wing closer to its ultimate load, and hence accelerate fatigue and stress over its lifetime? I mean, is it a case of comfort VS longevity?

[formulaben]

I'm not an engineer, so I have no idea, except to say that the above is my experience. I'm sure it depends on the type(s) of materials used, etc. Hopefully MadScientist will share.