Why does the Pilatus have this on its ailerons?

SixPapaCharlie

SixPapaCharlie

May the force be with you
Joined
Aug 8, 2013
Messages
17,547
Display Name
First Officer 6PC
What is the purpose of this lip thing on the trailing edge?

PIlatus.jpg
 
It's some kind of workaround for stick forces, apparently, because they had to use small span ailerons in order to fit unusually large flaps. It's replaced with a normal tab on NG (well, kinda normal - it's strange because it includes its own counter-balance!).
 
aerodynamically....the thickness or boundary layer grows from the leading edge to the trailing edge. My guess is this is a boundary layer trip to enhance aileron feel.
 
nauga said:
It's a Gurney flap, probably to increase control forces if they're on both ailerons.
Click to expand...

Thanks! The 162 has something similar on the elevator trim tab:
As well as reducing the sweep of the vertical stabiliser, lengthening the rudder and incorporating an underside aft ventral fin, Cessna has also placed a "Gurney" T-strip on the trailing edges of the trim tab to desensitise elevator control to help avoid pilot-induced oscillations in pitch.
Click to expand...
 
It's a flettner tab. They added it when the started with the -47 models. Makes the airplane feel like it looks like it should fly. The older models are much heavier on the controls than you would expect.
 
The employee screwed up and installed it upside down. It should be the other way,. 90 degrees to the left when facing perpendicular to the horizontal axis.
 
it prevents ho's from sliding off as you're tapping that GIDDYUP


OR a flettner tab, depending on how you ordered the part.
 
nauga said:
It's a Gurney flap, probably to increase control forces if they're on both ailerons.

Nauga,
who flaps to fly
Click to expand...
I was about ready to say, None of you guys watch open wheel racing, cause thats a Gurney flap.
 
Being that it's on the lifting surface of the control surface my guess is the Gurney flap is there to keep airflow attached to the aileron in a right roll for better feel or roll performance.
 
image.jpeg Helicopters use them as well. You can see the Gurney flap on the trailing edge of the vertical fin here. There's also another one on the bottom of the horz stab that you can't see.
 
Last edited:
Ok. You guys might be right about the gurney flap. It has those too. I couldnt tell from the picture exactly what he was looking at.
 
Velocity173 said:
View attachment 48927 Helicopters use them as well. You can see the gurney flap on the trailing edge of the vertical fin here. There's also another one on the bottom of the horz stab that you can't see.
Click to expand...
yup....but what you showed isn't a gurney flap...:eek:
Gurney_flap.png

gurney_flap_sketch.jpg

motorsport-aerodynamics-22-728.jpg
 
Checkout_my_Six said:
yup....but what you showed isn't a gurney flap...:eek:
Gurney_flap.png
Click to expand...

On the trailing edge of the vert fin IS a Gurney flap. It's even stated in the aircraft manual as a Gurney flap. Another example on the Bell 222.
 

Attachments

  • image.jpeg
    image.jpeg
    45.3 KB · Views: 27
I think these trailing edge angles and extrusion attached to flight controls has more to do with control surface flutter mitigation techniques more than anything.
 
bnt83 said:
I think these trailing edge angles and extrusion attached to flight controls has more to do with control surface flutter mitigation techniques more than anything.
Click to expand...
Leading and trailing edge flow treatments (flaps, slots, wedges, etc) rarely have anything to do with mitigating flutter unless the intent is to add so much drag you can't reach your flutter speed ;)

Nauga,
and a little bzzztBANG
 
Dave Theisen said:
Ok. You guys might be right about the gurney flap. It has those too. I couldnt tell from the picture exactly what he was looking at.
Click to expand...
Ah Ha!! I knew you've never even been in a PC12. I bet you dont even know how many tie down loops there are in the rear baggage area... and certainly cant land one in a 1000ft long, dirt and moose turd mountain strip @21,000' DA with the starting O-line from the Falcons on board, full fuel and bags. Like a REAL PC12 pilot could.


:D
 
nauga said:
Leading and trailing edge flow treatments (flaps, slots, wedges, etc) rarely have anything to do with mitigating flutter unless the intent is to add so much drag you can't reach your flutter speed ;)

Nauga,
and a little bzzztBANG
Click to expand...

Rigidity...smidgity. Flutter makes it go faster, by flapping like a hummingbird. My aerodynamical & phrenology texts from 1895 say so.
 
It was specifically put there to make you ask questions and nothing else.....:)
 
nauga said:
It's a Gurney flap, probably to increase control forces if they're on both ailerons.
Click to expand...
gurney.jpg

Not aviation-related, but here's a pic of the Gurney Bubble. When Dan was racing GT40s back in the day, he was too tall (6'4") to fit comfortably, so fabricator Phil Remington ginned this up for extra head room.

Dan's a class act. I don't know him well, but once played a round of golf with him and his son Alex. Alex holed out his approach shot on a par-5 for what I believe was his first eagle. Gurney Eagle...the significance was not lost on me.
 
ChemGuy said:
Ah Ha!! I knew you've never even been in a PC12. I bet you dont even know how many tie down loops there are in the rear baggage area... and certainly cant land one in a 1000ft long, dirt and moose turd mountain strip @21,000' DA with the starting O-line from the Falcons on board, full fuel and bags. Like a REAL PC12 pilot could.


:D
Click to expand...
Oh yeah? Hold my beer and watch this s***!
 
Now that I looked at the picture on my iPad instead of on my phone outside on a sunny day, I clearly see that 6PC's picture was indeed focused on the gurney flap
 
Did you even use the search function or talk to a CFI before asking this question? Geez.
 
Checkout_my_Six said:
Yup....a CFI should know this stuff. :D
Click to expand...

Well, I'm pretty sure 6PC isn't a CFI but his former CFI should've covered Gurney Flaps on day one...along with other basic GA aero topics such as vortex generators, winglets, Whitcomb rule, Reynolds numbers, etc. :)
 
SixPapaCharlie said:
I still don't know where the fuel goes
Click to expand...

How would you? Your plane is fueled up for you before you even wake up in the morning, you ride the limo to the airport, drives you right to your starship, ramp already preflighted the plane and loaded your bags (oh they W&B good, no worries) for you so all you do is take 5 steps and you're in the driver's seat right? And off you go!
 
You must log in or register to reply here.
Back
Top