From Icing to Helipads: CFD-Based Solutions to Contemporary Rotorcraft Challenges
30 cze 2025
O artykule
Data publikacji: 30 cze 2025
Zakres stron: 57 - 83
Otrzymano: 05 maj 2025
Przyjęty: 09 cze 2025
DOI: https://doi.org/10.2478/tar-2025-0009
Słowa kluczowe
© 2025 Adam Dziubiński, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Fig. 1.
![Selected rotorcraft examples designed at the Institute of Aviation [7]: a) the JK-1 Trzmiel (1957)[2], b) the BŻ-4 Żuk (1959), c) the BŻ-1 Gil (1960), d) the IS-2 (1990), e) the ILX-27 (2012), f) the I-28 (2012).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=92054643de013ecffee90f243de5745966d18aee3995e8acc6f06f54e814305b&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 2.
![Prototype of the ILX-27 unmanned helicopter in flight [7] and its computational model showing a pressure distribution map.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=59e79cc5584f1200a5207958daf562aad033e637a6180be385c60345e99f8e71&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 3.
![a,b) Simplified representation of the duct, c) computational model showing the finite volume mesh of the periodic cutout of one blade, along with corresponding part of the simplified duct [12].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_003.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=a425cc1f736afd8dfe6a0df656e42a8f8844389e8cc260b92a4f8b4ab32649c2&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 4.

Fig. 5.
![Mesh changes and ice layer growth on a predefined blade cross-section, viewed along the radius (with blade tip at the bottom) [12].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_005.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=941690c9b7c4b18dcdfde693cb5bb82bc03d2fef467cdec1ee4b85b3a77bd22f&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 6.
![The pressure distribution and pathlines on the blade and the duct surfaces during ice accretion [12].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_006.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=dc5370de677aa0b63d9bf0ac44f9bde152d8c2ff93f0a32a4f042db7fb223cc8&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 7.
![Division of the model into named zones, the axial component of the aerodynamic force for the individual zones, and a total summary component [12].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_007.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=7a6eac309087497116f5982c69bf244073a247972182d6748622afeac02a430b&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 8.
![The aerodynamic force and moment components calculated at the center of the hub for one blade of the tail rotor [12].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_008.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=2184076795c0e4cb1e74624b4502b2e05a48cdb74f0a1bff4fa0fd60ff399e79&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 9.
![The three views of the I-28 autogyro [13].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_009.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=d2bbb7cb3e504dfa8bf7354f6f88c651c5c9624cdbd57c763c830b752c3514a9&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 10.
![Visualization of the rotor wake on a set of cross sections behind the propeller, and yawing moment coefficient as a function of sideslip angle [13]. The propeller wake at β=25° of sideslip angle (bottom right picture) is touching only the upper side of the left V-tail, causing negative stability.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_010.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=35f852eab7e4cc1d25dc97b646cb7834b6f0a20f17c3ac14d797e475c9901f3c&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 11.
![The exact geometry of autogyro (above) compared to the one used for the preflight calculations (below), and a cross section through the tail surface including the gap geometry between the tail stabilizer and the rudder [13].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_011.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=77f09c6122a07530555cce12cfc0a30ca7c336533168adab62fb94ed7050e8d8&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 12.

Fig 13.
![Analyzed modifications of the tail: upper left base geometry, extended ruder, and extended stabilizer (left), short and long tailplane and the Xenon autogyro in the same scale (right) [13].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_013.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=fc599ce9b351caf511c5c859aca7d8fd18deaf4209a8ae8c29c1391a1a1cf89f&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig 14.
![The yawing moment characteristics vs. sideslip angle of the tested configurations [13].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_014.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=78ccf93498a96a363a5591d2f8fa8b8df06f2a001b6792369caf35e3d79c80bb&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 15.
![Influence of ruder deflection on the yawing moment of the I-28 autogyro [13]. The dotted lines show the influence of the short tailplane on the deflected rudder, compared to flight test cases shown with continuous lines.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_015.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=92132eb69768d4b4f38b6beb07fd7d543f6c4c55a06cf1f6e908e5097520619a&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 16.
![The Kopter SH-09 helicopter in flight [16] and its simplified 3D model [17].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_016.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=b338b8a072b5c9c0c0ce2c85362f4fadd39a51c6a04dd143ad50bc3ee431ae16&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 17.
![Simplified version of the nacelle model compared to the complex one, including all the installations inside [17].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_017.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=8afbdfd5bc24efab04b855f0dafcab9324d582c81b9fd01c56b4f006793aa6b3&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 18.
![The velocity magnitude visualization in a set of cross sections through the nacelle. Due to proprietary information constraints, only the colormap was shown in source [17] but the scale is identical in all cross sections..](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_018.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=565ab8b973b61189e8993591d87afb23d248919e8ece38a3b8421d092f723a65&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 19.
![The temperature field in hover for standard and “hot&high” conditions. Due to proprietary information constraints, only the colormap was shown in source [17] but the scale is identical in all cross sections.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_019.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=d15c61a156e4e331481030cf09ef92465e2a3b0e443767c86eab6a33d025e8d5&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 20.
![The temperature field in “hot&high” conditions for forward (a), backward (b) and sideways flight (c) [17].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_020.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=a42fdb415f0b1e8d6e2d25ed74519e74136bff63c6c226c2fa47239d5f28fb95&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 21.
![The PZL W-3 “Sokół” helicopter hovering over the courtyard of the Royal Castle in Warsaw, Poland, and downwind over the high building with one of its main gear wheels touching the roof [18].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_021.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=b1cfb371f32b193dee31374b1bdad8685bb31b7f2de8679ccccab5a7b3e1ed87&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 22.
![The vortex ring appearing during a hover over a well-shaped structure [19].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_022.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=3b90225b8cb94e049a47a86c2f54e8635b03bafcb931f2d1f87e5159d7582783&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 23.
![Examples of elevated helipad configurations: a) on the highest building, b) at the level of surrounding roofs c) near the highest building [20].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_023.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=afddd698738266bef96734abced056774ae879a8cbfa20135a9bc116e8e6baba&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 24.
![Helipad atop the Hospital in Katowice-Ochojec, where lifting of the helipad was analyzed [20].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_024.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=6a9b7f40196b2ba6e7b515cb130266d1bfba4c7426dcb821cb66cfabe27f2e29&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 25.
![Computational meshes for (a) at helipad at Copernicus Hospital in Gdansk, built on a platform at the level of surrounding roofs, and (b) a helipad built on the highest building in the vicinity, atop a hospital in Gdynia [22].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_025.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=ee7bba2d2c83c1344137d2707937168f45095497825b93065ad95eb1beeebafb&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 26.
![Helipad built on the same level as the surrounding roofs, where the influence of the rotor wake in hover, while rather safe on the left, will cause a partial vortex ring on the right [21].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_026.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=d797a71e9b70d3cf794f39667c7b83aff0a2ef089badf2d28d4afa5f75fbf0ae&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 27.
![Influence of a minimal air gap below the helipad surface on the flow quality above the helipad surface [20].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_027.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=e030a40e16694262987caa5e2b11b4d094f5e249be8073b3b4e1f2f33519d4cb&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 28.

Fig. 29.
![The path approaching the Gdynia Hospital from behind the “Sea Towers” building on the Gdynia waterfront, shown here emerging from the clouds, and the corresponding model in CFD [22,23]. The CFD results are shown in the plane at 3m above the helipad level and are inverted with respect to the photo.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_029.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=5132a043ffb531c1cd5dd6678d297ff8bf310eee379952e5fd58f2870318e613&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 30.

Fig. 31.
![The Copernicus Hospital in Gdansk – photogrammetric comparison between the model and an aerial photograph [22].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6869a05be88a4c302353f78c/j_tar-2025-0009_fig_031.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250909%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250909T123307Z&X-Amz-Expires=3600&X-Amz-Signature=f3cc6124b5eb33409d695de9d6b46d56961deea544b0c33e36f5df8e3946ed9c&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 32.

Fig. 33.
