1. Representing Aircraft Control Surface Deflection
John Ratzenberger
Eastern Carolina Plastic Modelers
New Bern, NC

2. Purpose
Over a period of years, I have seen models exhibiting outstanding technical workmanship, but basic aeronautical flaws. Likewise, I have talked with outstanding modelers who have some incorrect perceptions of real aircraft and flight. So, I thought I'd try to put something together that might be helpful.
We will discuss how to accurately model the movement/deflection of aircraft controls and control surfaces. While much of this will focus on an aircraft on the ground, it will also cover how to represent simple maneuvers in flight. At the end, attendees should understand the basic aircraft controls, the placement of the corresponding control surfaces, certain "usual" configurations, and where to go look for further information.
While useful to all aircraft modelers, it is oriented toward the "prop" modeler, not jet or helicopter modelers. It will not go into actually hacking the plastic, but it may save someone from having to correct a mistake..

3. Larger scales make it more important.
Why Bother ?
Kit Option ...
Aftermarket ...
More natural look ...
Jazz it up a bit ...
Fanatic over the subject ...
Show off modeling skill ...
Don’t Waste the Effort !!!
Larger scales make it more important.

4. Aircraft Nomenclature - Side View
Ailerons
Rudder
Vert. Stab./Fin
Wing
Trim Tab
(Horiz.) Stabilizer
Elevator
Rudder Bar/Pedals
Control Stick/Yoke

5. Aircraft Nomenclature - Top View
Rudder Bar/Pedals
Control Stick/Yoke
Flaps
Ailerons
Vert. Stab./Fin
(Horiz.) Stabilizer
Trim Tab
Elevator
Rudder

6. Aircraft Nomenclature - Back View
(Horiz.) Stabilizer
Rudder
Elevator
Vert. Stab./Fin
Control Stick/Yoke
Ailerons
Flaps
Rudder Bar/Pedals

7. Control Pitch around the Lateral Axis of the airplane.
Stick & Elevator
Stick/Yoke Forward
Elevator goes Down
Tail gains lift
Tail goes Up
so Nose Pitches Down
Control Pitch around the Lateral Axis of the airplane.
Stick/Yoke Back
Elevator goes Up
Tail looses lift
Tail goes Down,
so Nose Pitches Up

8. Rudder Pedals/Bar & Rudder
Pedals/Bar push with Left Foot
Rudder goes Left
Tail swings Right
Nose Yaws Left
Control Yaw around the
Vertical Axis of the airplane.
Pedals/Bar push with Right Foot
Rudder goes Right
Tail swings Left
Nose Yaws Right

9. Stick & Ailerons
Control Roll around the Longitudinal Axis of the airplane.
Stick/Yoke Left
Left Aileron Up
Left Wing looses lift.
Right Aileron Down
Right Wing gains lift.
Aircraft will Bank Left
& thus Turn Left
Stick/Yoke Right
Right Aileron Up
Right Wing looses lift.
Left Aileron Down
Left Wing gains lift.
Aircraft will Bank Right
& thus Turn Right

10. *** Differential and Frise ailerons will reduce Adverse Yaw.
A Coordinated Turn
Stick/Yoke Left
Left Aileron Up, Left Wing looses lift.
Right Aileron Down, Right Wing gains lift.
Aircraft will Bank Left & thus Turn Left.
Increased lift on Right Wing causes Increased Drag.
Increased Drag pulls nose to right (Adverse Yaw) ***.
So, a little Left Rudder to compensate.
And a little up elevator to hold the nose level.
*** Differential and Frise ailerons will reduce Adverse Yaw.

11. Control Surfaces at Rest & Play
Ailerons:
Being equal & opposite, will tend to a neutral position.
One Up, the other Down, never both up or both down.
Up / Down may not be same amount (Differential, Frise)
Spitfire: Up 26deg, Down 19deg
Wildcat: Up 19deg, Down 15deg
Frise
Neutral Up
Down

12. Control Surfaces at Rest & Play
Elevator:
Hinge is forward & weight is back, so will tend to down position.
Rudder:
Where left; if wind blown or moved, will tend to original position.
Nose Wheel, Tail Wheel/Skid & Rudder
Fixed
Free
Tied to rudder
Free - Tied - Locked.
Float/Sea Planes -- water rudder !!
Pilots park “square”, especially nose gear ...
General:
Stay in the 10-20deg range, avoid extremes.

13. Flaps Flaps: Four Basic Types of Flap:
Allow low-speed operation and control.
Shorten take-off distance.
Increase lift, increase drag.
Four Basic Types of Flap:
Plain
Split
Slotted
Fowler

14. Flaps In General On the Ground: Take-Off: Landing: Usually UP ...
May bleed down from hydraulics.
Plain Flap might be down to prevent walking on.
Take-Off:
Obstacle clearance, short or soft-field takeoff.
If used, then relatively small amount - no more than 1/2.
Landing:
“Always”
“Full” or nearly so, depending on conditions.
Usually one of 1st things done upon landing is Flaps UP.
Prevent damage from prop-blown debris
Eliminate cross/tail wind effects while taxiing.

15. Flap Examples F4U-1 Corsair F6F Hellcat P-47 Thunderbolt P-51 Mustang
Take-Off: 20deg
Landing: 30deg (Field), 50deg (Carrier)
F6F Hellcat
Take-Off: “As Required”
Landing: Down
P-47 Thunderbolt
Take-Off: Up (but “1/2 may improve take-off”)
P-51 Mustang
Take-Off: Up
Landing: Full Down
P-40 Warhawk
Take-Off: As Required, “never more than 1/2”

16. May have one of each or have both on a flying surface.
Trim Tabs
Trim tabs relieve the need for the pilot to maintain constant pressure on the flight controls.
Trim tabs “fly” the trailing edge of the control surface, so they will be opposite direction.
On the ground, the above may not hold.
Two Types:
-- Manually adjusted on ground
-- Adjustable in flight
May have one of each or have both on a flying surface.

17. Trim Tabs
Fixed
Adjustable in Flight

18. Trim Tab Examples F4U-1 Corsair, on Take-Off F6F Hellcat, on Take-Off
Rudder Tab -- set 6deg Nose Right
Aileron Tab -- set 6deg Right Wing Down
Elevator Tab -- set 1deg Nose Up
F6F Hellcat, on Take-Off
Rudder Tab -- two marks, Nose Right
Elevator & Aileron -- Neutral
P-47
Rudder Tab -- T.O. position is to right.
Elevator & Aileron - Neutral
P-40
All Tabs -- Neutral

19. Influences on “Natural”
Cable
Jackscrews
Hydraulic
Electric
Friction
Pivot Point
Balance
Locks

20. Cessna 172 - What’s “natural”?

21. Cessna 172 - What’s “natural”?
Parked, with control lock in, as per the Checklist.
Ailerons neutral, slight down elevator, rudder free.

22. References
Pilot’s Manuals
Photos
Books

23. End
Questions ?
Discussion ?
Suggestions ?