TY  - JOUR
A1  - Götten, Falk
A1  - Havermann, Marc
A1  - Braun, Carsten
A1  - Marino, Matthew
A1  - Bil, Cees
T1  - Wind-tunnel and CFD investigations of UAV landing gears and turrets – Improvements in empirical drag estimation
JF  - Aerospace Science and Technology
N2  - This paper analyzes the drag characteristics of several landing gear and turret configurations that are representative of unmanned aircraft tricycle landing gears and sensor turrets. A variety of these components were constructed via 3D-printing and analyzed in a wind-tunnel measurement campaign. Both turrets and landing gears were attached to a modular fuselage that supported both isolated components and multiple components at a time. Selected cases were numerically investigated with a Reynolds-averaged Navier-Stokes approach that showed good accuracy when compared to wind-tunnel data. The drag of main gear struts could be significantly reduced via streamlining their cross-sectional shape and keeping load carrying capabilities similar. The attachment of wheels introduced interference effects that increased strut drag moderately but significantly increased wheel drag compared to isolated cases. Very similar behavior was identified for front landing gears. The drag of an electro-optical and infrared sensor turret was found to be much higher than compared to available data of a clean hemisphere-cylinder combination. This turret drag was merely influenced by geometrical features like sensor surfaces and the rotational mechanism. The new data of this study is used to develop simple drag estimation recommendations for main and front landing gear struts and wheels as well as sensor turrets. These recommendations take geometrical considerations and interference effects into account.
Y1  - 2020
U6  - http://dx.doi.org/10.1016/j.ast.2020.106306
SN  - 1270-9638
VL  - 107
IS  - Art. 106306
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Götten, Falk
A1  - Havermann, Marc
A1  - Braun, Carsten
A1  - Marino, Matthew
A1  - Bil, Cees
T1  - Improved Form Factor for Drag Estimation of Fuselages with Various Cross Sections
JF  - Journal of Aircraft
N2  - The paper presents an aerodynamic investigation of 70 different streamlined bodies with fineness ratios ranging from 2 to 10. The bodies are chosen to idealize both unmanned and small manned aircraft fuselages and feature cross-sectional shapes that vary from circular to quadratic. The study focuses on friction and pressure drag in dependency of the individual body’s fineness ratio and cross section. The drag forces are normalized with the respective body’s wetted area to comply with an empirical drag estimation procedure. Although the friction drag coefficient then stays rather constant for all bodies, their pressure drag coefficients decrease with an increase in fineness ratio. Referring the pressure drag coefficient to the bodies’ cross-sectional areas shows a distinct pressure drag minimum at a fineness ratio of about three. The pressure drag of bodies with a quadratic cross section is generally higher than for bodies of revolution. The results are used to derive an improved form factor that can be employed in a classic empirical drag estimation method. The improved formulation takes both the fineness ratio and cross-sectional shape into account. It shows superior accuracy in estimating streamlined body drag when compared with experimental data and other form factor formulations of the literature.
Y1  - 2020
U6  - http://dx.doi.org/10.2514/1.C036032
SN  - 1533-3868
SP  - 1
EP  - 13
PB  - AIAA
CY  - Reston, Va.
ER  - 
TY  - JOUR
A1  - Götten, Falk
A1  - Havermann, Marc
A1  - Braun, Carsten
A1  - Marino, Matthew
A1  - Bil, Cees
T1  - Aerodynamic Investigations of UAV Sensor Turrets - A Combined Wind-tunnel and CFD Approach
JF  - SciTech 2021, AIAA SciTech Forum, online, WW, Jan 11-15, 2021
Y1  - 2021
U6  - http://dx.doi.org/10.2514/6.2021-1535
SP  - 1
EP  - 12
PB  - AIAA
CY  - Reston, Va.
ER  - 
TY  - CHAP
A1  - Ludowicy, Jonas
A1  - Rings, René
A1  - Finger, Felix
A1  - Braun, Carsten
A1  - Bil, Cees
T1  - Impact of Propulsion Technology Levels on the Sizing and Energy Consumption for Serial HybridElectric General Aviation Aircraft
T2  - Asia Pacific International Symposium on Aerospace Technology. APISAT 2019
Y1  - 2019
ER  - 
TY  - CHAP
A1  - Rings, René
A1  - Ludowicy, Jonas
A1  - Finger, Felix
A1  - Braun, Carsten
A1  - Bil, Cees
T1  - Sensitivity Analysis of General Aviation Aircraft with Parallel Hybrid-Electric Propulsion Systems
T2  - Asia Pacific International Symposium on Aerospace Technology. APISAT 2019
Y1  - 2019
ER  -