Miguel Rodriguez-Segade, Johan Steelant, Santiago Hernandez, and Jacobo Diaz
DOI Number XXX-YYY-ZZZ
Conference Number HiSST-2022-41
Slender hypersonic craft have potential applications ranging from point-to-point transportation to lowcost reusable access to space. For civil transportation, they are considered as the future technology
for high-speed commercial travel to any location of the planet in less than four hours. The successful
design of a cruising hypersonic aircraft will depend on a detailed balance between structural design,
aerodynamics, and propulsion.
Two major challenges when designing hypersonic vehicle within the air atmosphere are the thermal
management and structural capacity. Regarding thermal management, the aeroshell geometry determines the heat fluxes. In contrast to hypersonic blunt-body capsules, cruise vehicles require a higher
L/D ratio, hence exhibiting a more slender shape. As a result, heat is dissipated through near-wall phenomena along the wetted surface instead of strong bow shocks that would mainly heat the stagnation
area. For this reason, there is significantly more surface area that needs to be handled by the thermal
protection system. Beyond that, a sound structural design requires subsystems to be tightly integrated
within the airframe. Specifically, the fuel tanks must be accommodated to the external aerodynamic
surfaces and internal propulsive flowpaths, seeking an efficient compromise between internal volume
and structural weight. This multi-functionality can be achieved using the multi-lobe concept, which is a
promising solution for novel vehicle architectures [1].
In Europe, several projects were involved in the design of a hypersonic cruise vehicle. The LAPCAT
MR2.4 vehicle [2] consists of a waverider lifting-body with an integrated dorsal-mounted propulsion system. To be efficient during hypersonic cruise, the vehicle has leading edges with small radius to ensure
good aerodynamic efficiency (L/D). Fig. 1 shows the external skin of the aircraft, which can be divided
into a center fuselage section that contains the propulsive flowpath, and the delta wings.
Based on the design of the LAPCAT MR2.4 vehicle, the STRATOFLY MR3 was developed a few years
later. Fig.2b shows a comparison between the tank arrangements of the two vehicles. The STRATOFLY
MR3 contains gaps between some of the lobes to allow sufficient space for the landing gears and cabin
entrances. This solution was found to have flaws [3] and thus heavier than the one used for the LAPCAT
MR2.4 [4]. Therefore, an optimum continuous set of lobes from the tip to the end of the wing is sought
in this research, following the idea proposed during the LAPCAT project (Fig. 2a).
Although previous studies have shown promising results for this concept [5], a detailed study is needed
to analyze the benefits of the different multi-lobe configurations. In this sense, this research proposes
an optimization study to obtain the best multi-lobe configuration as an integral solution for a hypersonic
vehicle.