Josef Klevanski

Kerosene vs. Methane: A Propellant Tradeoff for Reusable Liquid Booster Stages

Kerosene and methane are two promising candidate propellants for a future reusable booster stage. This study assesses the merits of both propellants and compares their respective performance when used in a booster stage. First of all, the principal properties of both propellants are identified. An analysis of a comparable full-flow staged combustion cycle engine for each propellant follows. The final assessment is made based on the results of a performance analysis of a launch vehicle making use of these motors in reusable fly-back boosters. The use of kerosene as propellant leads to a lower booster dry mass, making it the preferred choice if no operational benefits of methane can be identified.

First-Stage Design Variations of Partially Reusable Launch Vehicles

This paper investigates different types of reusable first stages designed for a near term application with heavy lift launchers. The attached reference expendable space transportation system is a future Ariane 5 with cryogenic core and upper stage, but skipped solid rocket boosters. The design of the so called liquid fly-back boosters (LFBB) is restricted here to the incorporation of rocket motors already under development or in operation. LOX/RPI and LOX/LH2 combustion in different cycles is looked upon. The analyzed lay-out-variants of the reusable vehicle include attached single as well as dual LFBB-configurations. Catamaran type double fuselage stages are regarded to evaluate the potential in reducing the unsymmetrical thrust load of one side mounted boosters. Beside their primary use to boost heavy lift GTO missions, a second task may be covered by the same vehicle to accelerate the upper stages of small and medium launchers. The additional requirements in designing the same reusable launch vehicle for a least two different missions are studied. The investigation includes trajectory simulations and optimizations for ascent. Return to the launch site by the LFBB is regarded, concerning the propellant requirements and the loads on the vehicle. Different booster geometries are generated by CAD for a preliminary aerodynamic sizing, dimensioning, and mass estimation. Critical flight stability aspects are assessed by static and dynamic simulations. The paper includes a comparison of size and mass, as well as performance data of the different liquid fly-back booster configurations. The relevant rocket engine figures of performance, mass, reusability, and throttling capability are presented.

Preliminary Definition of Supersonic and Hypersonic Airliner Configurations

The propulsion system investigations of the EU sponsored LAPCAT study require the definition of generic reference vehicles to e.g. define the thrust level or assess a specific engine performance considering the reference mission of non-stop Brussels to Sydney flight. This paper describes DLR’s Space Launcher Systems Analysis SART group’s iterative definition of two configurations: The generic supersonic cruise airplane for a cruise Mach number of about four (designated LAPCAT-M4) is considerably enlarged compared to an earlier NASA design to meet the ambitious range requirement. Its propulsion system is based on Turbo-RAM with JP-propellant. The generic hypersonic Mach 8 cruise airplane (LAPCAT-M8) has been initially based on an innovative concept dubbed HyperSoar. The latter configuration uses hydrogen as fuel and an RBCC propulsion system. The paper gives an overview on the recent conceptual design status of the two passenger cruise vehicles presenting geometrical size and mass data and describing results of trajectory simulations and thus actually achievable range. Crucial system related design issues of the propulsion system, especially for the RBCC, will be discussed and critically assessed. Finally, an alternative technical option for high speed intercontinental passenger transport without airbreathing propulsion will be presented as a competitive benchmark.