Advanced propulsion technologies for future hypersonic strike weapons

Dominance in hypersonic systems is necessary to counter emerging threats from near-peer states such as China and Russia which are aggressively developing their own hypersonic capabilities. Indeed, a key component of the 2019 National Defense Strategy is developing and maintaining dominance in hypersonic weapon systems. While airbreathing hypersonic strike weapons have the potential to provide significant tactical advantages due to their speed, range, and maneuverability, they have a significant disadvantage: the dual mode ramjets (DMRJs) which power these weapons concepts have no low speed propulsion ability and require a solid rocket booster to get them up to the speed at which they can run, typically around Mach 4. This booster can comprise up over 40% of the gross weight and over a third of the total stack length of an all up round. Critically, this places severe constraints on the internal carriage of hypersonic airbreathing missiles on the F-35 and especially on the F-22 with its smaller bays.  As well, for the same AUR mass, if more of the weight is carried as rocket fuel instead of more efficient fuel for the airbreathing portion of the cycle, the range of the weapon will be limited. In order to enable hypersonic strike weapons compatible with the needs of the joint force, new, advanced propulsion alternatives to solid rocket boosters are required. In the phase I, the feasibility of replacing a rocket booster with a high Mach turbine coupled with a plasma-piloted dual mode ramjet to form a turbine based combined cycle missile was studied via reduced order trajectory studies and found to have the potential for significant system level benefits. In the phase I effort, the proposers also conducted interviews with various AF stakeholders to determine system requirements for hypersonic cruise missiles. Based on these systems requirements, the proposers will take a systems engineering approach, using various reduced order codes such as RJPA, and the Spacework's Quickshot code 3-DOF to conduct preliminary trade studies on a candidate combined cycle hypersonic cruise missile design. The proposed phase II effort will focus on a combined experimental and modeling effort to ground test a prototype demonstrator engine as well as conduct trajectory studies together with a major defense contractor to evaluate feasibility of using a turbine-based combined cycle architecture for future air-launched hypersonic cruise missiles as well as more broadly, the potential mission benefits the proposed technology may have for high speed air breathing weapons. The proposed turbine-based combined cycle architecture would leverage improvements in low-cost, attritable turbines as well as in plasma-assisted combustion for improved mode transition performance.