Wing loading

[Frogs97]

Does anyone have any input on how much wing loading truly impacts stability? Wing loading for 172s/Cherokee 180s seem to be in the 15 lbs/sq ft range. 182s/Dakotas around 18 lbs/sq ft, PA32 around 20 lbs/sq ft, and the SR20/22 are around 23 lbs/sq ft.

When dealing with bouncing around on hot afternoons, how much difference does 3, 5, or even 8 lbs/sq ft make?

 

[nauga]

When dealing with bouncing around on hot afternoons, how much difference does 3, 5, or even 8 lbs/sq ft make?

*very* roughly, about 1:1. A 10% increase in wing loading will reduce the normal acceleration in turbulence (the g's you feel in the bumps) at the same speed by ~10%. Not exactly, but close enough for the concept.

Nauga,
and his filling removal system

 

[Henning]

Quite a bit on the turbulence side, I'm not sure which factor of stability you are referring to.

 

[Frogs97]

*very* roughly, about 1:1. A 10% increase in wing loading will reduce the normal acceleration in turbulence (the g's you feel in the bumps) at the same speed by ~10%. Not exactly, but close enough for the concept.

Nauga,
and his filling removal system

Thanks, that is the start I needed.

Quite a bit on the turbulence side, I'm not sure which factor of stability you are referring to.

Really I was mostly referring to it's resitance to bouncing around in the afternoon bumps.

My kids love to ride up front, and my wife is perfectly content to let them take their turns. But, that means she's sitting in the back so I am also concerned about yaw stability. I just didn't figure that wing loading came into play on that, though. It just means a v-tail is almost certainly not in my future.

 

[Checkout_my_Six]

It just means a v-tail is almost certainly not in my future.

Since you brought it up....that V-tail thing is mostly due to the dihedral in the main wing. Dihedral is classically less stable and is the contributor to the dutch roll.

Other Beechcraft with the same wing have the dutch roll....it just isn't as pronounced.

My V-tail has a yaw damper autopilot and the dutch roll isn't noticeable.

 

[Henning]

Thanks, that is the start I needed.



Really I was mostly referring to it's resitance to bouncing around in the afternoon bumps.

My kids love to ride up front, and my wife is perfectly content to let them take their turns. But, that means she's sitting in the back so I am also concerned about yaw stability. I just didn't figure that wing loading came into play on that, though. It just means a v-tail is almost certainly not in my future.

"Tail Wagging" is actually pretty easy to control. Use the rudder pedals to pick up the wings instead of the ailerons. Most people who complain fly with their feet flat on the floor.

 

[l8evator]

"Tail Wagging" is actually pretty easy to control. Use the rudder pedals to pick up the wings instead of the ailerons. Most people who complain fly with their feet flat on the floor.

I agree with Henning that using rudder to pick up a wing is the way to smooth the ride. Trying to catch every little roll displacement can get tiring and I have noticed substantial improvement by simply holding a bit of light pressure on both rudder pedals, thus preventing the ruddervators from floating free. Further, lowering the landing gear will add even more stability in rougher conditions but at the trade off of cruise speed.

Scott

 

[nauga]

Really I was mostly referring to it's resitance to bouncing around in the afternoon bumps.

Just by way of trivia, that's usually referred to as 'ride quality,' or 'gust response,' and is largely unrelated to stability in an aerodynamic sense.

Nauga,
and his Dryden turbulence model

 

[Pilawt]

"Tail Wagging" is actually pretty easy to control. Use the rudder pedals to pick up the wings instead of the ailerons. Most people who complain fly with their feet flat on the floor.

Even one foot resting lightly on one rudder pedal does a lot to mitigate the BE35's tail wag.

Having flown all three extensively, I don't think the BE35's yaw response in turbulence is significantly worse than that of a T-tail Arrow or a Grumman-American AA-5x.

 

[Cpt_Kirk]

"Tail Wagging" is actually pretty easy to control. Use the rudder pedals to pick up the wings instead of the ailerons. Most people who complain fly with their feet flat on the floor.

Huge pet peeve of mine.

 

[Henning]

Even one foot resting lightly on one rudder pedal does a lot to mitigate the BE35's tail wag.

Having flown all three extensively, I don't think the BE35's yaw response in turbulence is significantly worse than that of a T-tail Arrow or a Grumman-American AA-5x.

Yeah, I really never saw that big of a difference, but my feet stay on the rudders regardless what I'm flying.

 

[Hank S]

Most people who complain fly with their feet flat on the floor.

Can't sit it a Mooney with your feet on the floor. I do find, however, that resting one foot on a rudder pedal will make the plane fly that direction. It's two feet or no feet for me.

When it's turbulent, I keep both feet on the rudders and hold the yoke with more than just fingertips. If it's really turbulent, I'll grab the yoke with both hands. If it's too rough, it will often smooth out considerably just by pulling the throttle back a little bit (at least it takes the jolt out of the big ones). Just tell your pax you hit an air pocket . . .

 

[tinerj]

Yes, the rudder is the last control surface to lose authority in most situations, and the first to use in making a smoother ride -- said by a non-rudder user until I started flying a tail dragger.

 

[Stewartb]

wing loading isn't the whole story. Airspeed makes a difference. I recall a very bumpy ride home in my Cessna and after landing I launched right back intonit in the cub to gauge the difference. Bumps in a 90mph Cub are soft compared to the jarring impact of the same bumps in a 150mph Skywagon.

 

[Frogs97]

Yeah, I really never saw that big of a difference, but my feet stay on the rudders regardless what I'm flying.

That is actually always something that always made sense to me. I guess I don't have a lot of XC time yet to develop the habit of moving my feet, but my instructors have always complemented my use of the rudder in flight. Ironically, it's overuse while taxiing that they harp on. I'm just trying to keep the wheel on the pretty yellow line!

 

[Henning]

That is actually always something that always made sense to me. I guess I don't have a lot of XC time yet to develop the habit of moving my feet, but my instructors have always complemented my use of the rudder in flight. Ironically, it's overuse while taxiing that they harp on. I'm just trying to keep the wheel on the pretty yellow line!

Even on long flights I use the rudder to make small corrections. If it's bumpy and I have pax, I always start with rudder pressure first to prevent the adverse yaw that makes people vomit. The skidding sensation is one everyone is used to since it's what you feel in a turn with a car. The slipping effect of adverse yaw is opposite so it bothers people a lot more. In bumpy conditions it's pretty much impossible to maintain perfect coordination, so best to hedge by keeping the motion on the skid side.