Figure 2 - uploaded by Martin Schubert
Content may be subject to copyright.
Source publication
A major aspect with respect to the electrification of aircraft is the concept of distributed propulsion which allows the total power demand of the aircraft to be allocated to multiple smaller and power-efficient electric engines. The need or desire for electrification creates a potential business case for aircraft manufacturers and operators who se...
Contexts in source publication
Context 1
... include substeps and provide guidance for establishing retrofits to be verified for compliance with the certification regulations, in particular strength and stiffness requirements. The process is visualized in Figure 2 and demonstrated in section 4 based on the example introduced in section 1.3. The process consists of the following stages and substeps: ...
Context 2
... to the heaviest REF wing with 100 % fuel (Figure 4), the integration of the OUT mass at the wingtip reduces the natural frequency of the first bending mode -from 3.3 Hz to 2.6 Hz and 3.0 Hz respectively (Figure 11). This effect is more pronounced with maximum battery mass, causing a drop to only 2.1 Hz and 2.3 Hz (Figure 12). For the DP wings mode 3 represents the first, and mode 5 the second torsion mode. ...
Context 3
... the DP wings mode 3 represents the first, and mode 5 the second torsion mode. While the eigenfrequencies of these modes decrease notably after integration of the battery modules into the wing, the differences of the results between the configurations M2 and M3 are moderate (Figures 12 and 13). Apparently, the mass moment of inertia of the battery has greater impact on the torsion modes than their chordwise position within the wing box. ...
Context 4
... on the results presented in the sections 4.5 and 4.6 the selection of suitable design parameters for the retrofit is evaluated in order to obtain a design proposal for the two DP configurations. The proposed retrofit design for the DP4 and DP6 wing is shown in Figure 22, which is the same illustration as for the final design of this paper presented in section 4.8. The design parameters are chosen based on following considerations: ...
Context 5
... the same level of torsion relief for the inner wing, as provided by the original turboprop engine, cannot be achieved through the integration of the electric powertrain and the battery modules. Figure 20 shows the first five modes up to the second torsion IFASD-2022-154 mode for both DP wings. For both designs no critical flutter velocities occur below 1.2·v D , as can be seen in Figure 21. ...
Context 6
... 20 shows the first five modes up to the second torsion IFASD-2022-154 mode for both DP wings. For both designs no critical flutter velocities occur below 1.2·v D , as can be seen in Figure 21. It shows that for this wing the strength requirements are more critical than the stiffness requirements. ...
Context 7
... both of the proposed retrofitted designs presented in the section 4.7 do not meet the strength requirements for airworthiness partial structural modifications are introduced. The proposed design parameters for the two DP configurations depicted in Figure 22 are maintained. The structural modification is applied to both spar webs between the structural root at y/(b/2) = 0.09 and the inner propulsion unit at y/(b/2) = 0.3 by increasing the sheet thickness by the reciprocal of the local minimum reserve factor of the spar web, as given in Figure 19d. ...
Context 8
... to the REF wing shown in Figure 3b, the differences between the rigid wings and flexible wings are more pronounced. The minimum reserve factors along the span are provided in Figure 24 and show that the reserve factors are RF ≥ 1 for the spars and satisfy the strength requirements eventually. Due to the partial and very localized structural modification no relevant changes in the modal parameters and flutter characteristics were encountered compared to the proposed retrofitted designs in section 4.7. ...
Citations
... The studies in this paper were preceded by quasi-static and flutter analyses of the wing structure of these three aircraft configurations. The results, including additional information about the powertrain specifications and the creation of the structural model of the reference wing, were presented at the 19th International Forum of Aeroelasticity and Structural Dynamics [2]. ...
... Instead, the space inside the wing structure is used to accommodate part or all of the battery modules. A suitable distribution of the propulsion systems and the battery mass for the DP configurations was determined in the preceding work [2]. It is the basis of the work presented in this paper and it is depicted in figures 2b and 2c. ...
... Hz respectively, to 17.1 Hz for DP4 and to 15.9 Hz for DP6. Detailed information about the mass breakdown of the wing and the powertrains, the structural model and the modal properties are provided in [2]. ...
The integration of distributed electric propulsion and energy storage systems into the wing structure significantly affects the mass distribution of the wing. Compared with conventional aircraft which are designed with engines mounted on the inner wing and integral fuel tanks, this substantially changes the overall loads on the wing structure. Assuming a retrofit scenario, this paper studies the influence of transient gust and landing impact loads on the dynamic behavior and the structural integrity of the wing of a representative conventional 19-seater commuter aircraft of CS-23 category retrofitted with distributed electric propulsion. Modal and dynamic response analyses are conducted based on a beam model idealizing the wing box of three wing designs: the reference wing with one main turboprop engine per half-wing, and two wings with integrated distributed electric propulsion. The results show for both load cases that the wing section loads obtained by dynamic response analysis exceed those predicted by equivalent quasi-static calculations. Compared with the reference wing, a significant increase of the amplitudes of the plunge and twist deformation and consequently higher section loads and stresses are observed for the retrofitted wing designs. It is concluded that both load cases are critical with regard to the structural integrity of the wing. However, the gust load case is more critical than the landing load case. These conclusions suggest that for the structural sizing of the wing, in particular for wings with distributed propulsion, and with regard to gust and landing impacts, the commonly applied quasi-static analyses should be accompanied by dynamic response analyses.
