Figure 1.

Figure 2.
![Conical rocket nozzle [7].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647392254e662f30ba542639/j_tar-2023-0007_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251106%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251106T091850Z&X-Amz-Expires=3600&X-Amz-Signature=476c1b4e2f8b3508f0d31cdf175b1be760b79d26b740b6d4da133add7ef7d124&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Figure 14.

Figure 15.

Figure 16.

Figure 17.

Figure 18.

Figure 19.
![Comparison of base drag coefficients obtained by CFD and the analytical model found in [4].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647392254e662f30ba542639/j_tar-2023-0007_fig_019.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251106%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251106T091850Z&X-Amz-Expires=3600&X-Amz-Signature=5da2af33bacac52eef45635653a1dd946c3c352bb0a1e42a1202aa9c35ed8cc1&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 20.

Figure 21.

Figure 22.

Computed drag coefficients_
| M [-] | ΔCD[–] | ||
|---|---|---|---|
| 0.3 | 0.460 | 0.453 | -0.007 |
| 0.6 | 0.378 | 0.457 | 0.079 |
| 0.8 | 0.359 | 0.462 | 0.100 |
| 1.0 | 0.494 | 0.668 | 0.170 |
| 1.2 | 0.628 | 0.744 | 0.120 |
| 1.6 | 0.577 | 0.659 | 0.080 |
| 2.0 | 0.506 | 0.576 | 0.070 |
| 2.5 | 0.435 | 0.495 | 0.060 |
| 3.0 | 0.383 | 0.429 | 0.046 |
Grot main dimensional parameters_
| Parameter | Value [m] |
|---|---|
| Total rocket length | 2.000 |
| First stage length | 0.983 |
| Second stage length | 1.017 |
| First stage diameter | 0.135 |
| Second stage diameter | 0.045 |
| Reference diameter | 0.135 |
| Pre-flight distance of centre of mass from the rocket’s base | 0.979 |
| Nozzle exit diameter | 0.084 |