J Intell Robot Syst (2013) 69:131–146
137
for optimum performance in an iterative fashion.
Lastly, from the two concepts, one of them is se- lected in terms of performance, manufacturability and cost.
The initial analysis of the wing geometry de- sign process is performed by using the program
XFLR5
.
XFLR5
utilizes Vortex-Lattice-Method which gives preliminary results from which the configurations can be compared.
After the optimization of these two different wing configuration concepts, estimated values from XFLR5 were compared. The drag coefficient was found to be equal to 3.1 N for the first concept in trimmed loiter condition. For the second con- cept we found the drag coefficient to be equal to
3.13 …show more content…
In order to select the wing profile, various air- foils are analyzed with
XFOIL
program and by us- ing UIUC Airfoil Coordinate Database. Airfoils are compared based on their Cmac, Clmax and
Cl/Cd ratio (Fig.
6
).
For the longitudinal static stability of the flying- wing, airfoil’s moment around the aerodynamic center must be positive. The airfoils which ensure such moment characteristics are sometimes called as reflexed airfoils because they have negative camber near the trailing edge. The pitch up mo- ment of the reflexed airfoils will neutralize pitch down effect of the wing’s lift. This is because of the fact that in tailless configurations with fuse- lage pods, aircraft’s center of gravity is generally in front of the aerodynamic center. It can be seen in Fig.
7
, the reflexed profile helps to get stability/trimability of the aircraft as its Cm o is greater than “0”. In addition the front position of
Fig. 6
Airfoils’ analyzes: Fauvel 14% airfoil is chosen because of positive C m and favorable Cl/Cd value at cruise
138
J Intell Robot Syst (2013) 69:131–146
Fig. 7
Forces around the wing of the tailless …show more content…
5 CFD Analysis
In our design process we have used Compu- tational Fluid Dynamics (CFD) analysis [
6
]. to solve for aerodynamic properties of the complete
UAV including the wing and the fuselage pod.
Specifically, such an analysis can give deeper in- sight to the designer in conceptual design phase by enumerating the effects of the changes made on the aircraft’s configuration. In addition it allows the designer to verify initial estimations and analy- sis. For the ITU Tailless UAV initial drag and lift estimations, we have utilized the XFLR5 program.
To further show the associated CFD methodology developed for mini UAV designs, we detail our
CFD analysis step-by-step in the next subsections.
5.1 Mesh Generation
For CFD solutions we have utilized the
137
for optimum performance in an iterative fashion.
Lastly, from the two concepts, one of them is se- lected in terms of performance, manufacturability and cost.
The initial analysis of the wing geometry de- sign process is performed by using the program
XFLR5
.
XFLR5
utilizes Vortex-Lattice-Method which gives preliminary results from which the configurations can be compared.
After the optimization of these two different wing configuration concepts, estimated values from XFLR5 were compared. The drag coefficient was found to be equal to 3.1 N for the first concept in trimmed loiter condition. For the second con- cept we found the drag coefficient to be equal to
3.13 …show more content…
In order to select the wing profile, various air- foils are analyzed with
XFOIL
program and by us- ing UIUC Airfoil Coordinate Database. Airfoils are compared based on their Cmac, Clmax and
Cl/Cd ratio (Fig.
6
).
For the longitudinal static stability of the flying- wing, airfoil’s moment around the aerodynamic center must be positive. The airfoils which ensure such moment characteristics are sometimes called as reflexed airfoils because they have negative camber near the trailing edge. The pitch up mo- ment of the reflexed airfoils will neutralize pitch down effect of the wing’s lift. This is because of the fact that in tailless configurations with fuse- lage pods, aircraft’s center of gravity is generally in front of the aerodynamic center. It can be seen in Fig.
7
, the reflexed profile helps to get stability/trimability of the aircraft as its Cm o is greater than “0”. In addition the front position of
Fig. 6
Airfoils’ analyzes: Fauvel 14% airfoil is chosen because of positive C m and favorable Cl/Cd value at cruise
138
J Intell Robot Syst (2013) 69:131–146
Fig. 7
Forces around the wing of the tailless …show more content…
5 CFD Analysis
In our design process we have used Compu- tational Fluid Dynamics (CFD) analysis [
6
]. to solve for aerodynamic properties of the complete
UAV including the wing and the fuselage pod.
Specifically, such an analysis can give deeper in- sight to the designer in conceptual design phase by enumerating the effects of the changes made on the aircraft’s configuration. In addition it allows the designer to verify initial estimations and analy- sis. For the ITU Tailless UAV initial drag and lift estimations, we have utilized the XFLR5 program.
To further show the associated CFD methodology developed for mini UAV designs, we detail our
CFD analysis step-by-step in the next subsections.
5.1 Mesh Generation
For CFD solutions we have utilized the