TY  - CHAP
A1  - Finger, Felix
A1  - Braun, Carsten
A1  - Bil, Cees
T1  - Comparative assessment of parallel-hybrid-electric propulsion systems for four different aircraft
T2  - AIAA SciTech Forum 2020, 06.01.2020 - 10.01.2020, Orlando
Y1  - 2020
U6  - http://dx.doi.org/10.2514/6.2020-1502
ER  - 
TY  - JOUR
A1  - Finger, Felix
A1  - Braun, Carsten
A1  - Bil, Cees
T1  - Impact of Battery Performance on the Initial Sizing of Hybrid-Electric General Aviation Aircraft
JF  - Journal of Aerospace Engineering
N2  - Studies suggest that hybrid-electric aircraft have the potential to generate fewer emissions and be inherently quieter when compared to conventional aircraft. By operating combustion engines together with an electric propulsion system, synergistic benefits can be obtained. However, the performance of hybrid-electric aircraft is still constrained by a battery’s energy density and discharge rate. In this paper, the influence of battery performance on the gross mass for a four-seat general aviation aircraft with a hybrid-electric propulsion system is analyzed. For this design study, a high-level approach is chosen, using an innovative initial sizing methodology to determine the minimum required aircraft mass for a specific set of requirements and constraints. Only the peak-load shaving operational strategy is analyzed. Both parallel- and serial-hybrid propulsion configurations are considered for two different missions. The specific energy of the battery pack is varied from 200 to 1,000 W⋅h/kg, while the discharge time, and thus the normalized discharge rating (C-rating), is varied between 30 min (2C discharge rate) and 2 min (30C discharge rate). With the peak-load shaving operating strategy, it is desirable for hybrid-electric aircraft to use a light, low capacity battery system to boost performance. For this case, the battery’s specific power rating proved to be of much higher importance than for full electric designs, which have high capacity batteries. Discharge ratings of 20C allow a significant take-off mass reduction aircraft. The design point moves to higher wing loadings and higher levels of hybridization if batteries with advanced technology are used.
Y1  - 2020
U6  - http://dx.doi.org/10.1061/(ASCE)AS.1943-5525.0001113
SN  - 1943-5525
VL  - 33
IS  - 3
PB  - ASCE
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  - JOUR
A1  - Götten, Falk
A1  - Havermann, Marc
A1  - Braun, Carsten
A1  - Gomez, Francisco
A1  - Bil, Cees
T1  - RANS Simulation Validation of a Small Sensor Turret for UAVs
JF  - Journal of Aerospace Engineering
N2  - Recent Unmanned Aerial Vehicle (UAV) design procedures rely on full aircraft steady-state Reynolds-Averaged-Navier-Stokes (RANS) analyses in early design stages. Small sensor turrets are included in such simulations, even though their aerodynamic properties show highly unsteady behavior. Very little is known about the effects of this approach on the simulation outcomes of small turrets. Therefore, the flow around a model turret at a Reynolds number of 47,400 is simulated with a steady-state RANS approach and compared to experimental data. Lift, drag, and surface pressure show good agreement with the experiment. The RANS model predicts the separation location too far downstream and shows a larger recirculation region aft of the body. Both characteristic arch and horseshoe vortex structures are visualized and qualitatively match the ones found by the experiment. The Reynolds number dependence of the drag coefficient follows the trend of a sphere within a distinct range. The outcomes indicate that a steady-state RANS model of a small sensor turret is able to give results that are useful for UAV engineering purposes but might not be suited for detailed insight into flow properties.
Y1  - 2019
U6  - http://dx.doi.org/10.1061/(ASCE)AS.1943-5525.0001055
SN  - 1943-5525
VL  - 32
IS  - 5
PB  - ASCE
CY  - New York
ER  -