Downwind turns

[S2D]

AND OTHER STUPID AG PILOT OBSERVATIONS.


the kid I sold my spray business to came to me today and asked : How come when the temperature reaches 80 deg in the morning the plane flys like a dog, but when it gets down to 80 in the evening it flys like a raped ape?

I could only laugh and tell him don't spread that nonsense around or pretty soon you'll start noticing that downwind turns suck more than upwind turns at times and everyone will start thinking you are just a dumb ag pilot.

Too late!! He has already observed that too.

 

[OLDCROWE]

I stopped in Forsyth this afternoon for fuel, but the mechanics said you were fiddling around somewhere… nice pump install!

 

[WhiskeyMike]

AND OTHER STUPID AG PILOT OBSERVATIONS.


the kid I sold my spray business to came to me today and asked : How come when the temperature reaches 80 deg in the morning the plane flys like a dog, but when it gets down to 80 in the evening it flys like a raped ape?

I could only laugh and tell him don't spread that nonsense around or pretty soon you'll start noticing that downwind turns suck more than upwind turns at times and everyone will start thinking you are just a dumb ag pilot.

Too late!! He has already observed that too.

Simple... Raped Ape is a relative term. It's because it was 100“F in the afternoon,

 

[S2D]

I stopped in Forsyth this afternoon for fuel, but the mechanics said you were fiddling around somewhere… nice pump install!

Thanks !!
(I go North for the summer !!)

 

[S2D]

Simple... Raped Ape is a relative term. It's because it was 100“F in the afternoon,

We aren't comparing it to how it flew at 100, we are comparing it to how it flew at 80 deg in the morning. In the morning when it reaches 80, your staggering around in the turns. In the evening you are practically doing hammerhead turns.

 

[mvivion]

We aren't comparing it to how it flew at 100, we are comparing it to how it flew at 80 deg in the morning. In the morning when it reaches 80, your staggering around in the turns. In the evening you are practically doing hammerhead turns.

That’s because by evening, you’re too damn tired to pay much attention…….or give a hoot.

 

[BC12D-4-85]

My computer's AI Genie knows all - tells all. If it's more humid in the morning than at night....

"Density decrease:
As humidity increases, the proportion of lighter water vapor molecules in the air increases, while the proportion of heavier nitrogen and oxygen molecules decreases. This results in a lower overall density for the humid air"

Edit: Thinking about early morning flying floats....also seems doggy when foggy or just plain humid vs later in the day when the air drys out some. Might be power, might be lift changes.

Gary

 

[stewartb]

Maybe the hangover was worn off.

 

[cubdrvr]

I see a couple of Tongue In Cheek dismissals
I find it prudent to listen to the experience of folks who know “ first hand” and learn from them.

 

[KevinJ]

Only first hand experience I have is that every crop duster I’ve ever been around encourages tongue in cheek, disparaging and off color comments directed in every direction which I find enjoyable

 

[StalledOut]

Moist air in the morning will increase density altitude. Later in the day after that moisture burns off and DA decreases.

 

[BC12D-4-85]

Here's a Density Altitude calculator that uses Dew Point and other stuff> https://wahiduddin.net/calc/calc_da.ht

Gary

 

[S2D]

Definitely might be on to something with the humidity. I think air stability has more to do with it. Same thing that affects downwind turns

 

[BC12D-4-85]

^^^^Interesting observation re unstable air. True for sure as the earth heats with the sun or hot air moves in. Later in the day clouds and air subside and settle with less solar. Maybe then less change to the relative winds near the ground. Can affect turns or the feel in my experience as the plane briefly speeds up or slows relative to the surrounding wind. from any windshear.

Gary

 

[MT12]

Thanks !!
(I go North for the summer !!)

Jordan or Sand Springs

 

[S2D]

Jordan - Cohagen

 

[aktango58]

^^^^Interesting observation re unstable air. True for sure as the earth heats with the sun or hot air moves in. Later in the day clouds and air subside and settle with less solar. Maybe then less change to the relative winds near the ground. Can affect turns or the feel in my experience as the plane briefly speeds up or slows relative to the surrounding wind. from any windshear.

Gary

Yup. Flying the salmon management guys around I had to shut down a couple of sunny 'calm' days. The slight downslope winds in the canyons would give me a slight push every time I would turn away from the hills- dropping my already slow speeds. Those canyons were not places you could add 10 kts and still get the job done.

Stable air allows one to bring the speeds down and still have control at all times. Bouncing around trying to be accurate on my landing spot never seems to work out well.

Bottom line, are we meeting in Forsythe Mt. to discuss this theory late this fall?

 

[BC12D-4-85]

I think speed can mask deviation in airspeed or lift. By that I mean cruising along or turning we move quickly though any windshear or change in relative wind. Bump bump, perhaps a quick deviation in airspeed or altitude, not enough to register to the pilot or pitot.

Slow down to survey or application speeds like 1.3Vs and the events slow as well. Just guessing but that may give time to recognize the effects. Like landing and trying to remain stabilized on the approach vs driving at speed through changes in relative winds with lateral and/or vertical flow.

Some day go fly the standard banking turns while maintaining the required ACS standards of performance. Do it at cruise speed then at slow approach to stall speeds. If there's any shear or marked change in relative wind I can feel the aircraft reacting more when slowed down.

Gary

 

[stewartb]

I’m surprised at this topic. Air stability? Why is the temperature coolest just before dawn? Because air above ground is warmed by the sun and cooler air sinks to the ground, right? That means better flight performance near the ground to me. And where I live (near mountains and ocean) the winds are lighter in the morning. Morning humidity may be higher but that disadvantage is overcome by other factors.

 

[BC12D-4-85]

In Fairbanks "coolest just before dawn" often results from surface air, cooler and heavier than warmer air above is laying in low spots due to overnight IR radiation. It's advected by pressure/flow as the Sun or any winds aloft approach. Slides downhill.

Even in winter we get that surface flow as evidenced by furnace exhaust bending away from nearby hills towards the lowlands along the Tanana River. It eventually mixes downwards if faster air above, but in real cold the temperature inversion (colder at the surface than above) can remain.

The early AM effect of air instability is less in Summer, but windshear layers can form between the slow moving surface and any differential flow above. Mechanical upset from terrain adds to the condition.

Gary

 

[BC12D-4-85]

I'll add another "what if" about a recent accident. An experienced pilot in a Citabria was testing VG's on a cold mid-winter day. Slow flight near normal stall (from observed GPS GS of course) was documented by the NTSB below 1500' AGL. The plane descended with flaps deployed through what I believe was a shear layer formed from winds aloft (he was heading into them) down into relatively calm colder surface air. Speculation. At trial the jury was convinced the tail had stalled. Whatever the cause an experienced pilot rode controlled flight into terrain.

Did the relative wind change and contribute to the accident?

Gary

 

[BC12D-4-85]

Read this if interested in wind shear, turbulence, and the effects on aircraft while maneuvering.

Aviation | Hazards | Turbulence and Wind Shear | World Meteorological Organization

community.wmo.int

Gary

 

[S2D]

Bottom line, are we meeting in Forsythe Mt. to discuss this theory late this fall?

That could be a possibility !!

 

[DJ]

I would vote for relative humidity being a factor. I’ve been told that high humidity is like adding 1000 ft to the density altitude at temps above 80F. I haven’t found a way to verify that but this chart seems to agree.

 

[stewartb]

I don’t fly paper graphs, I fly airplanes. Being a typical human, my perceptions are based on feelings. Vision, equilibrium, energy…. All are sharper later in the day.

This performance discussion is very similar to the downwind turn discussion. We’re humans. Ground based creatures. Accustomed to boundaries. We fly by numbers or fly by feel. Most of us use both but feel is dominant when close to the ground using ground references and avoiding hitting things. Pireps are not science, but those perceptions are real just the same.