An Evaluation of Two Alternate Propulsion Concepts for Bantam-Argus: Deeply-Cooled Turbojet+Rocket and Pulsed Detonation Rocket+Ramjet
The Bantam-Argus reusable launch vehicle concept is a smaller version of the original Argus single-stage-to-orbit launch vehicle design. Like the original Argus, Bantam-Argus uses a Maglifter launch assist system to provide an initial horizontal launch velocity. Bantam-Argus is designed to deliver 300 lb. payloads to low earth orbit and, like the full sized Argus, the baseline Bantam-Argus concept utilizes two liquid oxygen/liquid hydrogen supercharged ejector ramjets as prime motive power. This paper presents the results of an investigation of two alternate propulsion systems for the BantamArgus launch vehicle. First, a thermally integrated combined-cycle system consisting of two deeplycooled turbojets and two liquid rocket engines was evaluated. Second, a combination propulsion system utilizing two pulsed detonation rocket engines and two standalone ramjets was evaluated. The results show that both alternate propulsion systems have the potential to reduce both the dry weight and gross weight of the baseline Bantam-Argus concept (when resizing the vehicle while holding mission payload constant). The pulsed detonation rocket engine option is particularly attractive. However, these results must be treated with caution given the relative immaturity of the supporting propulsion data available for both alternatives. Trade studies on key performance parameters were p rformed to bound the potential gains to be expected from either alternative.
Prospects for Detonations in Propulsion
The application of detonations for propulsion has received widespread attention recently. Some of the attractions for utilizing detonations include the higher theoretical thermodynamic efficiency compared to deflagration-based systems, high power-to-weight ratio and few moving parts. Despite these attractive features, a number of fundamental physics and engineering challenges must be overcome before such propulsion systems can be practical. Specifically, focusing on the aerothermodynamic aspects of detonation-based propulsion, some of these issues involve the unsteadiness of the flow, mixing of fuel and oxidizer, detonation initiation and propagation, etc. These issues will be discussed within the context of different detonation-based engine architectures. The pathway from fundamental research to practical systems will be illustrated.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.