Project VALHALLA

My role on the team was as the Co-Lead to a team of 8 engineers and to design the structural and mechanical subsystem of the spacecraft. This also involved final implementation of all other subsystems. As an aerogravity assist is an entirely theoretical maneuver that has only been mathematically proven, designing a spacecraft to conduct one was a unique challenge.

An aerogravity assist is a maneuver where while performing a gravity assist, a spacecraft will dip into the atmosphere of the planet and use a lifting surface to have a sharper change in flight angle. As such, the structure needed to perform such a maneuver is a unique blend of aerospace and spacecraft concepts. The first step I took was to calculate was the Mach we would be flying at when performing the maneuver on Venus and Mars.

Mach Calculations for Venus

Mach Calculations for Mars

As shown in the images above, the approximate Mach at Venus is 69 and at Mars is 76. This would mean the spacecraft is at hypersonic speeds. Moving forward, I took inspiration from hypersonic and supersonic aircraft to develop the exterior for the spacecraft. Two aircraft were used, the Mach 25 Waverider and the F-14 diamond shaped fuselage.

Waverider Analysis

The left images show the diagrams found for the Waverider and a CAD mock up I made in Solidworks to represent an early concept of the design.

The waverider was selected because it is designed to fly at high Mach numbers and provided a hypothetical structural design for me to base my spacecraft model off of.

Diamond Truss Analysis

The images to the right shows the diamond shaped truss designed in NX. The first image is using the Real Eigenvalues solutions to test whether the truss could withstand vibrations during launch with a maximum nodal displacement of 0.158 mm.

The following two images show the Static Loads FEA for maximum load conditions with the selected launch vehicle (about 8gs). There was a maximum displacement of 0.721 mm, max strain of 2.971 *10^-4, and max stress of 23.12 MPa.

Diagram depicting folding of variable sweep wing

Wing Design

Variable sweep wings are often used in aircraft that need to operate at different Mach numbers. A large concern was the spacecraft entry angle into the planet causing a negative or unbalanced lifting force on the wings, so having wings that folded outwards was ideal.

Assumptions made: Angle of attack of 0 degrees and flight computer controlled hydraulic actuators that can withstand flight loads

Lifting Analysis Assumptions

For aircraft flying at Mach 70, hypersonic flow conditions get very complicated. Molecules in the atmosphere begin to ionize, a bow shock forms over the nose, this kind of analysis was out of scope for the time constraints of the project. Instead, the structure was modeled as though it was flying at Mach 5 with the following assumptions:

L/D at Mach 5 will be sufficient at higher Machs
Thermal change across shock is negligible
Wing actuators can withstand forces during flight

While these are pretty severe assumptions, they are ultimately necessary to developing a design for the spacecraft.

The airfoil was modeled as a diamond, and the total lift was calculated from the pressure differential between the upper and lower surface. In the diagram to the right, section 0 represents the planet atmosphere at Mach 5.

Final CAD

The final CAD consisted of a truss 5.17m x 3.10m x 1.79m with a foldable wing design. The structure houses all necessary components of the spacecraft and can withstand all forces during launch and nominal operation.

View the final presentation here

331b_FinalPresentation_Valhalla_20230428.pptx