Supersonic Inflatable Aerodynamic Decelerator Research Articles

The Effect of Roll Rate on Simulated Entry Vehicle Ballistic Range Tests

Free-flight computational fluid/rigid-body dynamics simulations are now being explored as a way to augment physical experiments for characterizing the dynamic behavior of blunt-body atmospheric entry vehicles. Initializing these simulations with accurate initial conditions is critical to achieving validation against experimental results and characterizing vehicle behavior. This paper explores the impact of a nonnegligible initial roll rate on numerical free-flight simulations of ballistic range tests using the FUN3D Navier–Stokes flow solver and POST2 trajectory propagator. These ballistic range shots were performed on a model of the Supersonic Inflatable Aerodynamic Decelerator at the NASA Ames Hypervelocity Free-Flight Aerodynamics Facility. In the absence of measured roll data, a method for reconstructing the initial roll rate is developed assuming that a nonnegligible roll rate accounts for the exchange in amplitude between the experimental pitch and yaw data. Simulations of three shots spanning a range of initial roll rates are executed to evaluate the new method. Results are validated against the physical ballistic range tests. Simulations with the reconstructed roll rate are more accurate to the experimental data than those assuming a negligible initial roll rate. Direct calculation of the pitch damping coefficient also captures the effect of roll rate on pitching moment.

Computational Fluid Dynamics Simulations of Supersonic Inflatable Aerodynamic Decelerator Ballistic Range Tests

The free-flight behavior of entry vehicles can greatly impact vehicle and mission design. Current methodologies rely heavily on ground and flight experiments, while computational fluid dynamics is largely used as a complement to experiments in the form of static aerodynamic databases. The dynamic stability of entry vehicles is primarily studied through ballistic range experiments and flight tests. In an effort to validate the predictive capabilities of computational fluid dynamics for free-flight aerodynamic behavior, numerical simulations of a ballistic range experiment are performed using the unstructured finite-volume Navier–Stokes solver, US3D. The ballistic range tests used for comparison in this paper were performed on a scaled model of the Supersonic Inflatable Aerodynamic Decelerator geometry. The purpose of these experiments was to provide aerodynamic coefficients of the vehicle as an a priori analysis of dynamic stability coefficients ahead of the Supersonic Flight Demonstration Test. The range data span the moderate Mach number range, 3.8–2.0, with a maximum total angle-of-attack range, 10–20 deg. These conditions are intended to span the Mach/angle-of-attack space for the majority of the flight test. Comparisons to raw vehicle attitude and postprocessed aerodynamic coefficients are made between simulated results and experimental data. The resulting comparisons for both the raw model attitude and derived aerodynamic coefficients show good agreement with experimental results. Additionally, near-body pressure field values for each trajectory simulated are investigated. Extracted surface and wake pressure data give further insight into dynamic/flow coupling, leading to a potential mechanism for dynamic instability.

Reconstruction of Atmosphere, Trajectory, and Aerodynamics for the Low-Density Supersonic Decelerator Project

The Supersonic Flight Dynamics Test was a full-scale flight test of aerodynamic decelerator technologies developed by the Low-Density Supersonic Decelerator technology development project. The purpose of the project was to develop and mature aerodynamic decelerator technologies for landing large mass payloads on the surface of Mars. The technologies included an attached toroidal Supersonic Inflatable Aerodynamic Decelerator, a ballute, and supersonic parachutes. Two flight tests were conducted at the Pacific Missile Range Facility. Sufficient data were acquired to reconstruct the vehicle trajectory, main motor thrust, atmosphere, and aerodynamics for these two flight tests. This paper describes the instrumentation, analysis techniques, acquired data, and reconstruction results from these two flight tests. A technique for processing gimballed inertial measurement unit data is developed in which the inertial flight path of the instrument is reconstructed, which is then mapped back to the vehicle body frame as a postprocessing step.

Investigation of Drag-Modulated Supersonic Inflatable Aerodynamic Decelerators for Sounding Rocket Payloads

The goal of this investigation is to understand the sizing and performance of supersonic inflatable aerodynamic decelerators for Earth-based sounding rocket applications. The recovery system under examination is composed of a supersonic inflatable aerodynamic decelerator and a guided parafoil system to achieve sub-100 m miss distances. Three supersonic inflatable aerodynamic decelerator configurations (tension cone, attached isotensoid, and trailing isotensoid) are examined using the metrics of decelerator mass, aerodynamic performance, and vehicle integration. In terms of aerodynamic performance, the tension cone is the preferred choice for the sizes investigated. The attached isotensoid was shown to be the most mass efficient decelerator, whereas the trailing isotensoid was found to be the more ideal decelerator for vehicle integration. A three-degree-of-freedom trajectory simulation is used in conjunction with Monte Carlo uncertainty analysis to assess the landed accuracy capability of the proposed architectures. In 95% of the cases examined, the drag-modulated inflatable aerodynamic decelerator provides arrivals within the 10 km parafoil capability region, meeting the sub-100 m landed recovery goals. In 76% of the cases examined, the drag-modulated inflatable aerodynamic decelerator arrives within 5 km of this target zone.

Supersonic Inflatable Aerodynamic Decelerators for Use On Future Robotic Missions to Mars

The 2009 Mars science laboratory mission is being designed to place an 850 kg rover on the surface of Mars at an altitude of at least one kilometer. This is being accomplished using the largest aeroshell and supersonic parachute ever flown on a Mars mission. Future missions seeking to place more massive payloads on the surface will be constrained by aeroshell size and deployment limitations of supersonic parachutes. Inflatable aerodynamic decelerators (IADs) represent a technology path that can relax those constraints and provide a sizeable increase in landed mass. This mass increase results from improved aerodynamic characteristics that allow IADs to bedeployed at higher Mach numbers and dynamic pressures than can be achieved by current supersonic parachute technology.During the late 1960's and early 1970's preliminary development work on IADs was performed. This included initial theoretical shape and structural analysis for a variety of configurations as well as wind tunnel and atmospheric flight tests for a particular configuration, the attached inflatable decelerator (AID). More recently, the program to advance inflatable decelerators for atmospheric entry (PAI-DAE) has been working to mature a second configuration, the supersonic tension cone decelerator, for use during atmospheric entry.This paper presents an analysis of the potential advantages of using a supersonic IAD on a proposed 2016 Mars mission. Conclusions drawn are applicable to both the astrobiology field laboratory and Mars sample return mission concepts. Two IAD configurations, the AID and tension cone, are sized and traded against their system-level performance impact. Analysis includes preliminary aerodynamic drag estimates for the different configurations,trajectory advantages provided by the IADs, and preliminary geometric and mass estimates for the IAD subsystems. Entry systems utilizing IADs are compared against a traditional parachute system as well as a system employing an IAD in the supersonic regime and a parachute in the subsonic regime. Key sensitivities in IAD design are included to highlight areas of importance in future technology development programs.