Introduction:
This page is dedicated to those
people that like the world of radio control airplanes, especially big
sailplanes, and want to test new ideas with the purpose of improve the
performance of their models.
The airfoils presented here
have been optimized thanks to the program “Xfoil”, and to the
generosity of “Mark Drela”, who permits that the program is free
available in the net. The obtained graphics have been generated in
postscript with “Xfoil” and converted with the programs “Gsview” and
“Ghostcript” to “pdf” format, so they can be visualized with the
program “Acrobat Reader”.
The “H”, “U” and “Y” airfoils
have been designed starting from a defined speeds distribution, which
give the airfoil form as a result of an inverse process. For this
reason, other airfoils of these families cannot be precisely generated
scaling the coordinates in the usual way. Camber has been optimized
computing polars with “Xfoil”. The routines employed to compute the
airfoils are based on approximate methods that have the great advantage
of allowing the definition of the speeds distribution with few
parameters, and in a very simple way. They have been developed by me.
The “E”, “K” and “T” airfoils
have been designed starting from speeds distributions of other
airfoils,
and modifying them with the routine “Qdes” of “Xfoil”. Camber and
thickness are optimized computing polars.
Many great success airfoils
have been carefully studied: RG, HQ, Eppler, Selig, NACA, etc. Their
design concepts and speeds distributions have been related with the
computed polars. The cumulative experience has been large and the
airfoils presented here are the result. The methods employed for
computing the coordinates are very precise, and the obtained speeds
distributions do not have the bumps that sometimes appear in other
airfoils like the published HQ.
The computed polars include the
placement of turbulators before the flaperon hinges, with the purpose
of simulate the presence of sealing tapes or to improve the
characteristics with deflected surfaces. Turbulators have been
satisfactorily tested in flight by some friends and me, and are
composed of 2 layers of car decoration tape of 1 mm. width, to achieve
a total thickness comprised between 0.20 and 0.25 mm.
In order to notice the expected
improvements and to judge the results in an objective way, is necessary
that the building process is reasonably precise. The most sensitive
airfoils to construction defects are de “H”, “K”, “U” and “Y” series.
These airfoils also prefer polish surfaces because of their laminar
design.
Success of an airplane design
requires good aerodynamics, and airfoils are only one of the
contributions. A wrong design will be wrong forever, even if you use
the best airfoil; and a good design will be good, even if the airfoil
is not the best. The final result is the sum of tiny things that give
the success.
All airfoils and material
presented here are “free”. If this information is going to be
distributed, I want that the original coordinates are
kept and their source mentioned. Although these airfoils can be used
freely, I would appreciate your feedback. Because of this reason,
please send an email including your
name, address, phone number, place where you fly, indicate if you are
member of some club, your experience, and the type of airplanes you
usually fly. I am very interested in knowing the results of your tests
and with which airplanes they have been done.
Reference Airfoils:
Fx60126m
Mh32m
Rg15m
Rg15m11
Developed Airfoils:
Exx1711
H451809
H452010
H452211
H452312
Kxx2911
Txx3017
U651411
U651412
Y652411
Y652512
Rxx
Series
Airfoil set designed not specifically for flaps or turbulators. Anyway
flaps should improve performance.
There are several main forms, P00 (max. thickness at 25% chord), P100
(max. thickness at 35% chord) and intermediate ones.
All of them are scaled to 18% thickness and 3.5% camber and the speeds
distributions smoothed. All airfoils could be obtained scaling the
coordinates inside that range.
Camber should fix the end of the low drag range at high speed.
Selecting airfoils with different thickness and thickness positions
along the chord and span, maximum local Cl could be
controlled and hence the stall
behavior of the wing. Detailed polar calculations should be done with
"Xfoil" for the appropriate Reynolds number.
Y65 Series
Airfoil set designed specifically for flaps and turbulators. Flap chord
20%. Turbulator extrados position 65-70%. Turbulator intrados position
65-67%.
These airfoils are designed with an inverse process and defined speeds
distributions. That's why scaling coordinates should not be done since
the speeds distributions are altered. Intermediate airfoils could be
approximated interpolating the nearest ones.
Z Series
Airfoil set designed specifically for flaps and turbulators. Flap
chord 18%. Turbulator extrados position 70%. Turbulator intrados
position 77%. These airfoils are designed with an inverse process and
defined speeds
distributions. That's why scaling coordinates should not be done since
the speeds distributions are altered. Intermediate airfoils could be
approximated interpolating the nearest ones.
Airfoils Comparison:
Exx1711 & Rg15m11 Re:
0.20e+6 Flap: 0.0º
1.00e+6 Flap: 0.0º
H452211 & Rg15m11 Re:
0.20e+6 Flap: 0.0º
1.00e+6 Flap: 0.0º
U651412 & Rg15m11 Re:
0.20e+6 Flap: 0.0º
1.00e+6 Flap: 0.0º
Exx1711 & H452211 Re:
0.20e+6 Flap: 0.0º
+7.5º
1.00e+6 Flap: 0.0º
-5.0º
Exx1711 & U651412 Re:
0.20e+6 Flap: 0.0º
+7.5º
1.00e+6 Flap: 0.0º
-5.0º
-2.5º
H452211 & U651412 Re:
0.20e+6 Flap: 0.0º
+7.5º
1.00e+6 Flap: 0.0º
-5.0º
-2.5º
H452211 & H452312 Re:
0.10e+6 Flap: +7.5º
0.20e+6 Flap: +7.5º
1.00e+6 Flap: -5.0º
Kxx2911 & U651411 Re:
1.00e+6 Flap: -7.0º & -2.5º
TL=0.61
for Kxx2911
TL=0.75
for Kxx2911
Kxx2911 & H452211 Re:
1.00e+6 Flap: -7.0º & -5.0º
TL=0.61
for Kxx2911
TL=0.75
for Kxx2911
Software:
- AdaFoil 1.51. Program for the inverse design of subsonic airfoils with the following features:
- Calculation of the airfoil that corresponds to a given pressure distribution.
- Calculation of the pressure distribution that corresponds to a given airfoil.
- Easy definition of the pressure distribution with three types of curves.
- Reads files in conventional "dat" format.
- Writes files in "dat" and "dxf" formats.
- Reads files
in conventional "dat" format. (e168
and e193 file examples included).
- Writes files in "dat" and "dxf" formats.
- Simple airfoil
modification: thickness and camber.
- Potential flow analysis
with simple flap simulation.
- Printing airfoils.
- Configuration of several
parameters.
Acknowledgements:
Especially to Mark Drela, who
permits the free use of “Xfoil” and access to the sources.
To Matthias Hänel, who
used a precursor of the airfoil U651412 in his models SUPRA-2 and
MAXXIMA-2, and has checked the validity of design and performance.
Who I am ?
My name is Juan Antonio Troya
Martínez, Aeronautical Engineer, born the 1st of May of 1962. I
fly radio control airplanes since 14 years old, and I am full size
sailplane pilot since 17 years old. I am also interested in
aerodynamics, programming of numeric methods in C, Fortran, Ada, Visual
Basic and Quickbasic.
I live in Puerto de la
Cruz, Canary Islands, Spain.
Contact:
mailto:jatroyam@telefonica.net
Page Revisions:
February 19, 2003
Page created
Airfoils
Mh32m, Rg15m, Rg15m11, Exx1711, H451809, H452211, Txx3017, U651412
included
February 24, 2003
Airfoil
H452312 included
March 3, 2003
Airfoil
H452010 included
March 5, 2003
Airfoil
Fx60126m included
March 7, 2003
Airfoil
U651411 included
April 18, 2003
Airfoil
Kxx2911 included
June 19, 2003
Airfoil
Kxx2911 revised
September 12, 2003
Airfoils
Y652411 and Y652512 included
January 23, 2004
"Airfoil Potential Flow 1.0" program included
January 18, 2005
Rxx and Y65 airfoil series included.
All coordinates could be downloaded without email
request.
April 8, 2005
Spanish version of web page included
Some small corrections added.
October 7, 2008
Link to "AdaFoil 1.49" program included
October 10, 2009
Z sirfoils included
Copyright © 2003-2009 Juan
Antonio Troya Martinez