Firstly, my initial research was quite a bit more in-depth (one can see this by comparing the number of cited articles between this report and my previous one - 9 vs. 36!) I read and reported on the dynamics of energy balance on Earth, solar radiation management, and previous studies, both in feasibility and design, of SRM aircraft. I also included the standard performance and geometry summary of similar aircraft, noting the unique design space that StratoSOL would occupy.

I also did some more work on building up my codebase, DSAeroTools, particularly when it came to its initial sizing capabilities. I developed modules for the creation of constraint diagrams and simple Breguet formulations. These allowed me to do some more detailed work in design space exploration. This report included baseline-parametric carpet plots for key performance metrics as well as wing area-cruise speed diagrams, something not present in my 2023 entry.

The layout was once again performed in OpenVSP, a tool which I was getting quite proficient with at this point after using it in last year’s competition and at other projects. Because the aerosol is quite dense, the layout was constrained primarily by the wing area required, V-tail moment arm, landing gear, and fuel volume space-claims.

Airfoil selection was thus driven by layout as well, something I encountered during the layouts for Project Caladrius. Not only were the polars and design lift coefficient/drag considered, but also the internal volume resulting from the use of the airfoils. Because this aircraft was flying at near-supersonic speeds, a study was also conducted on the drag divergence Mach of different supercritical airfoils.

StratoSOL’s weight analysis was another improvement from last year. Using various weight methods found in literature, results agreed closely with historical weight fractions to aircraft of similar design weights and missions (of course, take this with a grain of salt: this is hardly a victory due to the novel nature of the configuration…) This author also prepared CG excursion diagrams for different loading configurations, ensuring compliance with forward-aft CG limits.

Aerodynamic analysis was similar to the 2023 entry with some improvements: primarily DATCOM methods from Raymer, with studies of high-lift devices, shifting of neutral point at higher Mach numbers (”Mach tuck”), lift-curve slope changes with Mach numbers, etc. However, some improvements included more accurate drag buildups with a compressibility model (from Shevell) built into DSAeroTools.

Propulsion analysis was also improved. Something similar to last year was repeated, using Raymer’s methods for installed thrust corrections, with a representative turbofan scaled down to the selected powerplant’s thrust. This time the corrections were primarily inlet related, different from last year’s piston-prop corrections.

However, a higher-fidelity model was also used, namely J.D. Mattingly’s High BPR Turbofan model, described in more detail in Gudmundsson’s General Aviation Aircraft Design (along with a great discussion of thrust modeling for gas turbines in general). This model was used to predict the thrust curves at altitude and speed, and was also used for the performance analysis of Chapter 11.

This report also included a more thorough discussion on structural layout and flight loads. This author had learned of OpenVSP’s structures tools recently, so decided to use it with moderate success. This served well for notional structural through-views showing key ribs and spars and such.

A V-n diagram was also prepared using Andras Sóbester’s ADRpy (Aircraft Design Recipies in Python) tool.

Stability analysis was once again conducted with AVL and XFLR5 models of StratoSOL. Modeling a blended-wing body in those tools proved quite challenging, and later talks with colleagues who have attempted to predict stability behavior of these type of aircraft (blended/hybrid wing, or highly swept/delta planforms) in these vortex lattice solutions have made me grow skeptical of these results. Regardless, they were done in good faith, and yielded reasonably-looking numbers.

The report also included takeoff and landing performance charts, showing the ground rolls at varying altitudes, as well as with and without the assistance of thrust-reversers. Future work could include these same results but at different takeoff gross weights.

Lastly, a more thorough performance analysis (perhaps the more needed improvement from last year) was conducted. This verified StratoSOL’s ability to maintain level-flight at its target altitude of 65,000ft, and its ability to climb to that altitude in the first place.

Lastly, a simple cost analysis using RAND’s DAPCA IV model was performed, quite similar to last year’s.