DLR-SART contribution in LAPCAT studies
The first scientific and technological objective of the EU-funded multinational research project is outlined as:
"… to evaluate two advanced airbreathing concepts: a Turbine or Rocket Based Combined Cycle (TBCC/RBCC) capable of achieving the ultimate goal to reduce long-distance flights, e.g. from Brussels to Sydney, to less than 2 to 4 hours. Two reference vehicles including their characteristic trajectory points have to be established."
In LAPCAT1 the definition of two reference vehicles and their trajectories has been performed by DLR-SART. The statement on the Brussels to Sydney route translates into a range requirement of at least 16700 km along the orthodrome and hypersonic flight conditions.
The new generic supersonic cruise airplane for LAPCAT (designated LAPCAT-M4) has to be considerably enlarged compared to an earlier NASA design to meet its ambitious range requirement. The generic geometry of the LAPCAT configuration is shown above. The large, slightly inclined wing might help to achieve a good maximum L/D of 7.8 at a small angle of attack and cruise Mach number 4.5 according to preliminary DLR-analysis. Actually, a high L/D is essential to achieve the ambitious range requirement.
Historically, the proposals on hypersonic cruise airplanes seem to be much rarer than those on supersonic airliners. The US proposed Mach 10 HyperSoar has been used as the reference vehicle.LAPCAT-M8 is considerably enlarged compared to HyperSoar to accommodate the passengers and the cabin and to meet the ambitious LAPCAT range requirement.
LAPCAT2 is the successor of the completed LAPCAT1 study. Again, two vehicle concepts are being investigated, with a Mach 5 and a Mach 8 vehicle. In the current LAPCAT2 study DLR-SART is responsible for critical cross-check analysis for the Mach 8 vehicles in the preliminary design phase. This analysis includes aerodynamic and propulsion recalculations as well as mass budgets and trajectory simulations. Three different Mach 8 vehicle designs are still under investigation in LAPCAT2.