Exploration of Airfoil Sections to Determine the Optimal
Airfoil for Remote Controlled Pylon Racing
Michael DeRosa
Master of Engineering Final Project
What is Remote Control Pylon Racing?

3 Recognized Classes:
 424 class: 120 mph Quickie 500
 426 class: 150 mph Quickie 500
 Focus of Project
 422 class: 190-200 mph

Size of 426 Class airplanes determined by
Academy of Model Aeronautics rules
 Minimum weight of 3.75 lbs.
 500 square inches of wing area
 50-52 inches of win span
 Aspect ratio of 5
 Wing thickness to chord ratio is 0.11875
 Powered by methanol fueled Jett 0.40 cubic
inch engine displacement engine

Goal is to fly around a 2 mile course in shortest
amount of time
 Course is marked by 3 pylons: 2 are 100 ft.
apart and 1 is 475 ft. from the centerline of
the twin pylons
 4 planes race at a time
 10 laps
 Penalties for turning inside of pylons
Typical Q-500 pylon racer Viper 500 by Great Planes
Q-500 pylon race
Optimal Airfoil For Pylon Racing Not Explored
•No official studies on pylon racing airfoils completed to date
•Entering into a 50 ft. radius turn at 150 mi/hr creates 30 G’s of force acting on the plane
•Wing must pitch up to increase lift coefficient at expense of increased drag
•Increased drag can slow down a plane by 15-20 mi/hr in turns
•Even a 5 mph speed gain in turns is significant.
•Widely used airfoil for pylon racing is NACA 66-012 symmetrical laminar flow airfoil
•Drag penalties in turning flight translates to significant loss of speeds in turns
•Conversely, a cambered airfoil such a Clark Y will retain more speed in turns due to higher lift coefficients at
much lower drag increase; higher L/D than NACA 66-012 airfoil
•Trade off is lower maximum speed in straight ways due to higher form drag
•Modern airfoils created by Martin Hepperle, Selig, and Eppler are useful for drag minimization in pylon racing
•Wings with 2 different airfoil types have not been considered and/or assessed
NACA 66-012 Laminar Airfoil Typically Used for Pylon Racing
High Lift Clark Y Airfoil Not Typically Used for Pylon Racing
Project Utilized XFOIL Airfoil Development Program
•Developed by Dr. Mark Drela of MIT
•Uses solutions of viscous and invisicid differential equations to solve airfoil shape for:
•Lift coefficient for given angles of attack
•Drag polars to determine drag coefficient for a given lift coefficient
•Moment coefficient for given angles of attack
•Velocity ratio with free stream velocity over any given point over airfoil
•Pressure distribution over airfoil
http://web.mit.edu/drela/Public/web/xfoil
Methodology for Determining Optimal Airfoil
•Utilized XFOIL and published airfoil data to obtain necessary lift and drag coefficients for the
following airfoils:
•NACA 66-012 baseline
•Clark Y as high lift option
•Martin Hepperle
•Selig
•Eppler
•Airfoils with flaps
•Blended airfoil wings
•Each airfoil trial have wings and planes with following properties:
•500 square inches
•50 inches chord length
•Minimum thickness to chord ratio of 0.11875
•3.75 lb. airplane
•1.8 HP engine
•Derive equations for acceleration/deceleration in Maple
•Keys to winning pylon racer performance:
•Maximum speed during straight and level flight and:
•Minimal loss of speed in turns
Race Simulation
•Whole plane drag coefficient calculated from airfoil drag from straight and level flight and turns
•Maximum straight and level flight speed and maximum loss of speed in turns determine for all 32 airfoil candidates
•Top 12 performing airfoils run through race simulation in Maple
•Each simulation consists of a typical race consisting of each piece shown below
•Sea level air properties assumed, e.g. density, temperature, absolute viscosity
•Airfoil section is the only variable for each plane in this simulation
•Provides good relative comparison of airfoil performance
Pylon race course will incorporate:
•10 laps
•Assume 1 lap consisting of:
•2x 475.5 ft. straight ways
•2x 50 ft. radius semi circles
•12,65.16 ft. per lap
•Total distance covered in race simulation is
2.40 miles
Typical pylon race course layout set by Academy of Model Aeronautics rules
High Level Results
WINNER!!
Martin Hepperle MH-17 airfoil with 5 degree 15% span flaps during turns
Airfoil
MH-17 With 5 Degrees 15% Span Flaps
MH-17
MH-18B
S-8064
NACA 66-012 With 10 Degrees 15% Span
Flaps
MD5- Combination of NACA66-012 and
MH-18B (0.5 Interpolation)
MD6- Combination of NACA66-012 and
MH-17 (0.5 Interpolation)
MD1- Combination of NACA66-012 and
Clark Y (0.5 Interpolation)
E-220
NACA 66-012
MH-18
Clark Y
Cd @ CL = Cd @ CL =
0.018776 0.563277
Max Race
Speed
(mi/hr)
Max Speed
Loss in Turns
During Race
(mi/hr)
Race Time
(sec)
0.00437
0.00437
0.00470
0.00497
0.00507
0.00648
0.00594
0.00636
151.13
150.66
148.55
146.65
11.65
12.64
11.39
10.98
62.146
62.509
63.567
63.814
0.00528
0.00602
144.75
9.95
64.396
0.00490
0.00964
146.12
13.38
64.484
0.00487
0.00994
146.21
13.65
64.485
0.00543
0.00568
0.00528
0.00637
0.00810
0.00558
0.00579
0.01089
0.00538
0.00538
143.95
142.34
143.37
138.38
126.49
9.28
8.84
13.20
6.93
3.27
64.607
65.203
65.619
67.668
70.189
•Commonly used NACA 66-012 airfoil is one of the worst performers!!
•Can improve airfoil by use of flaps during turns, or
•Blending it with higher performing airfoil
•Clark Y is the slowest airfoil, as expected
Airfoil Drag Polar from XFOIL
Drag Polars are drag coefficient listed for each lift coefficient
NACA 66-012
Clark Y
MH-17
MH-18
MH-18B
S-8064
E-220
MD-1
MD-5
MD-6
CL = 0.018776
CL = 0.563277
0.40000
0.50000
0.60000
•Straight and level flight lift coefficient
of 0.18776 is marked by left dashed
line
•Turning flight lift coefficient of
0.563277 is marked by right dashed
line
•Clark Y has highest drag at level flight
•NACA 66-012 has highest drag during
turns
•MH-17 has lowest drag at level flight
•Highest top speed of any airfoil
•Relatively low drag in turns
makes it a winning combination
0.015
0.014
0.013
0.012
0.011
0.010
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0.000
0.00000
0.10000
0.20000
0.30000
Drag polar for 12 airfoils
0.70000
Flaps Increase Turning Performance of Airfoils
NACA 66-012 airfoil with 5 degree 15% span flaps during turns
0.03000
•NACA 66-012 is a symmetrical airfoil
•Flaps increase airfoil camber
•Laminar buckets shifts to the right with flaps
•Lift coefficient range where drag coefficient
is small
•Airfoil drag is reduced at higher lift coefficient in
turns
•Flapped airfoils require less angle of attack
to create same amount of lift, hence less
airfoil drag
•NACA 66-012 airfoil with 10 degree 15% span
flaps is in laminar bucket during turns, hence lower
drag
No Flaps
10 Degrees Flaps
CL = 0.563277
0.02500
Lift Coefficient
in Turns
Drag Coefficient
0.02000
0.01500
0.01000
0.00500
Laminar Bucket
Lift Coefficient
0.00000
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
NACA 66-012 Airfoil Can Be Blended with Other Airfoils To Improve Performance
NACA 66-012
MH-18B
MD-5
•MD-5 airfoil is
blend of NACA 66012 and MH-18B
airfoils
•Properties are
approximately
between these 2
airfoils
•Entire wing can
also be comprised
of MD-5 airfoil
Wing Dimensions:
•10 inch chord length
•50 inch span length
•500 square inches area
MD-5