High Wing vs. Low Wing in Turbulence

[CC268]

Hey guys,

Just to clarify this isn't a "which is better in turbulence" thread.

My PPL was done in a 1979 172N. I got used flying in turbulence/thermals as I flew a lot in the warmer months here in Arizona. Turbulence has always made me really nervous, but flying in it a lot helped with the fear.

Now I am flying a Cherokee 140 (owned by my dad and I) and turbulence seems like it "feels" different in this airplane than the 172. I feel like the airplane yaws a lot more in turbulence than the 172 did. It makes me nervous as I feel like it is really hard to keep the ball centered sometimes. I especially feel nervous about making a turn in these conditions as I think I might not keep the ball centered and I might get a weird gust of wind/turbulence and stall it and bam I'm in a spin or unusual attitude. It just seems so weird as I don't remember the 172 feeling like this in turbulence. I guess I just get really freaked out by the "feeling" of somehow not being in control by turbulence.

I have two weeks off in December and plan to go up with an instructor to get comfortable and confident again...Plan is to do some crosswind landings, fly to Payson, hopefully fly in some windy/turbulent conditions, steep turns. Ultimately I hope to do the Spin/Unusual Attitude Recovery program at Chandler Aerobatics.

Wow I probably sound like a real mess of a pilot lmao...this is like an AA meeting admitting all my problems.

 

[ircphoenix]

Weird. I actually prefer the feeling of my 140 to the 172s I trained in in turbulence. Must just be a different sensation mentally 'tween the two of us. =)

 

[tawood]

I'm with ircphoenix...I've always preferred the 140 to the 172 in turbulence (and crosswinds).

 

[kgruber]

Original Cherokee with short wings has higher wing loading than Cessna 172 and rides turbulence better.

get a few hours in a light tailwheel airplane, it will wake your feet up!

 

[Mtns2Skies]

The aerodynamics of a low wing's dihedral makes them "swim" constantly hunting for equilibrium which is why you feel the yawing sensation. A high wing has some dihedral but primarily is positively stable by the fuselage of the aircraft being an over-damped pendulum which makes the plane a touch more stable. But I'd always found aircraft with higher wing loading to be better in turbulence, which the cherokee has.

 

[Pilawt]

Now I am flying a Cherokee 140 (owned by my dad and I) and turbulence seems like it "feels" different in this airplane than the 172. I feel like the airplane yaws a lot more in turbulence than the 172 did.

It also has to do with the relative length of the fuselage and the tail design for lateral stability. As a generalization, airplanes with shorter, stubbier fuselages will tend to respond to turbulence with some tail-wagging. It's said that aerodynamicists like longer fuselages, while structural engineers prefer shorter ones. A 172 is 3-1/2 feet longer than a Cherokee 140, and has larger tail surfaces. With the longer wingspan and slightly lighter wing loading of the 172 you might feel a little more vertical acceleration in bumps, but yaw response to turbulence would be less.

I guess I just get really freaked out by the "feeling" of somehow not being in control by turbulence.

Not to worry. It would take a lot more than normal Arizona thermal turbulence to cause loss of control. Pretty soon you'll find yourself anticipating those slight yaw excursions and compensating for them with slight rudder inputs, without even thinking about it.

Wow I probably sound like a real mess of a pilot lmao

Nope. Sounds perfectly normal to me. And good on you for talking about it.

 

[CC268]

The aerodynamics of a low wing's dihedral makes them "swim" constantly hunting for equilibrium which is why you feel the yawing sensation. A high wing has some dihedral but primarily is positively stable by the fuselage of the aircraft being an over-damped pendulum which makes the plane a touch more stable. But I'd always found aircraft with higher wing loading to be better in turbulence, which the cherokee has.

I should have known this from my flight dynamics course I took in school...talked about all of this...and lots of MATLAB and calculating stability matrices, etc...butttt I forgot it alllll!

 

[Pilawt]

A high wing has some dihedral but primarily is positively stable by the fuselage of the aircraft being an over-damped pendulum which makes the plane a touch more stable.

Cessna put this logo into their 1961 single-engine ads:

 

[jordane93]

Feels the same to me.

 

[danhagan]

No one has mentioned it, but some planes have a yaw dampener ... mine doesn't, but I found by apply a little right rudder pressure, the yaw oscillating stops (this is for moderate TB meaning you have a zero percent chance of using the Gatorade bottle as a urinal without spilling).

 

[cowman]

Now that you mention it I do feel the yaw in my Archer on certain days when the wind is high and blowing the wrong way.

 

[Pilawt]

No one has mentioned it, but some planes have a yaw dampener

In his book about the development of the Cessna singles, former Cessna engineer and test pilot Bill Thompson wrote about the design of the cantilever wings in the late '60s Centurions.

I'm working from memory since all my books are packed away for a move. But as I recall, Thompson said they wanted the new wing for the '67 210G to be mounted as far aft as possible, for (1) better visibility and (2) to move the cantilever spar carry-through well behind the pilot's head. Having the wing so far aft dictated the planform of a straight leading edge and forward-tapered trailing edge, in order to have the C.G. in proper relationship to the mean aerodynamic chord. That resulted in a wing that performed as if it were slightly swept forward, which in turn reduced its directional stability. To recover some of that stability, they decided to increase the dihedral more than normally seen on high-wing airplanes.



Customers didn't like the look, so for 1969 (210J) they reduced the dihedral back to a more "normal" appearance, but then had to tweak control linkages and interconnects to salvage as much stability as possible.

Bottom line -- airplane design is an exercise in management of compromises. Changing any one feature, whether in the interest of speed, utility, appearance, or anything else, usually involves a chain reaction of unintended consequences.