Christopher L. Tanner

A historical review of Inflatable Aerodynamic Decelerator technology development

Viking-era deployable decelerator technology has been employed for several planetary probe missions at Earth and within other planetary atmospheres.1 2 Numerous system studies in the past fifty years demonstrate the benefit of developing a new decelerator technology capable of operating at higher Mach numbers and higher dynamic pressures than existing decelerators allow. The deployable Inflatable Aerodynamic Decelerator (IAD) is one such technology. This survey paper describes the development history of the IAD from its conception in the 1960s to the present day. Major findings in primary IAD sub-disciplines for the foremost configurations are discussed. Quantitative engineering data from prior testing is reproduced directly, while qualitative conclusions are referenced in the literature. This work provides a summary of past and present IAD technology development efforts and shows data in a manner useful for todays mission designers.

Structural Verification and Modeling of a Tension Cone Inflatable Aerodynamic Decelerator

Verification analyses were conducted on membrane structures pertaining to a tension cone inflatable aerodynamic decelerator using the analysis code LS-DYNA. The responses of three structures - a cylinder, torus, and tension shell - were compared against linear theory for various loading cases. Stress distribution, buckling behavior, and wrinkling behavior were investigated. In general, agreement between theory and LS-DYNA was very good for all cases investigated. These verification cases exposed the important effects of using a linear elastic liner in membrane structures under compression. Finally, a tension cone wind tunnel test article is modeled in LS-DYNA for which preliminary results are presented. Unlike data from supersonic wind tunnel testing, the segmented tension shell and torus experienced oscillatory behavior when subjected to a steady aerodynamic pressure distribution. This work is presented as a work in progress towards development of a fluid-structures interaction mechanism to investigate aeroelastic behavior of inflatable aerodynamic decelerators.

Lazarus: A SSTO Hypersonic Vehicle Concept Utilizing RBCC and HEDM Propulsion Technologies

14th AIAA/AHI Space Planes and Hypersonic Systems and Technologies Conference November 2006, Canberra, Australia

Aerodynamic Characterization of New Parachute Configurations for Low-Density Deceleration

The Low Density Supersonic Decelerator project performed a wind tunnel experiment on the structural design and geometric porosity of various sub-scale parachutes in order to inform the design of the 110 ft nominal diameter flight test canopy. Thirteen different parachute configurations, including disk-gap-band, ringsail, disksail, and starsail canopies, were tested at the National Full-scale Aerodynamics Complex 80by 120-foot Wind Tunnel at NASA Ames Research Center. Canopy drag load, dynamic pressure, and canopy position data were recorded in order to quantify the relative drag performance and stability of the various canopies. Desirable designs would yield increased drag above the disk-gap-band with similar, or improved, stability characteristics. Ringsail parachutes were tested at geometric porosities ranging from 10% to 22% with most of the porosity taken from the shoulder region near the canopy skirt. The disksail canopy replaced the ringslot portion of the ringsail canopy with a flat circular disk and was tested at geometric porosities ranging from 9% to 19%. The starsail canopy replaced several ringsail gores with solid gores and was tested at 13% geometric porosity. Two disksail configurations exhibited desirable properties such as an increase of 6-14% in the tangential force coefficient above the DGB with essentially equivalent stability. However, these data are presented with caveats including the inherent differences between wind tunnel and flight behavior and qualitative uncertainty in the aerodynamic coefficients.

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 1960s and early 1970s 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.

Deployment of the 30.5 meter Parachute on the Supersonic Flight Dynamics Test

The NASA Low Density Supersonic Decelerators (LDSD) project includes a highaltitude Supersonic Flight Dynamics Test (SFDT) that tests aerodynamic decelerators in the correct Mach/dynamic pressure environment for use on Mars landing missions. The 30.5 meter parachute of LDSD was developed to be mortar-deployed for future Mars use. However, the unique design of the Supersonic Flight Dynamics Test, with a center-mounted solid rocket, and the mass of the parachute (100 kg) precluded the use of a CG-aligned parachute mortar and required the development of a staged pilot deployment that preserved the canopy extraction characteristics of a mortar-deployed parachute. The architecture of the parachute deployment is discussed, including the use of a stiffened triple bridle, the elimination of the metallic bridle confluence fitting, the use of two deployment bags and the separation of the pilot device prior to line stretch. The extensibility to a mortar-deployed parachute is discussed along with the parameters that were assumed for a successful deployment and inflation. A multi-body dynamic simulation was developed to predict the performance of the parachute deployment and to tune the deployment parameters. The results of the simulation are compared to the performance of the system in the first SFDT flight, as well as ground-based development tests of the deployment sequence.

Pyrotechnically Actuated Gas Generator Utilizing Aqueous Methanol

A mechanically-initiated pyrotechnic gas generator was developed to aid in the inflation of the supersonic pilot ballute used by the Low Density Supersonic Decelerator (LDSD) project. The device is designed to pressurize the ballute following deployment, exposing and properly orienting its ram-air inlets to the freestream flow, to assist in its inflation process. The supplemental pressurization decreases the total inflation time and increases the likelihood of a successful inflation. Upon activation of the device, a pair of redundant firing mechanisms initiate pyrotechnic charges that pressurize and rupture a reservoir containing a mixture of methanol and water, ejecting the solution in to the ballute. The methanol subsequently rapidly vaporizes due to the low ambient pressure and latent heat in the ballute fabric, pressurizing the ballute. In addition to its role in inflation, the device serves as the structural connection to the ballute. Analytical models were developed for the inflation capability of the device, which were verified using vacuum chamber testing of developmental hardware. Static, deployment, and environmental testing demonstrated the functionality of the firing mechanism and reservoir under several temperature and pressure conditions. Finally, the device was successfully operated during the first Supersonic Flight Dynamics Test (SFDT) that occurred in June 2014. The design architecture is scalable to accommodate different quantities of the liquid solution, can be adjusted to operate in a variety of temperature and atmospheric pressure regimes, and provides a robust device that may be installed with minimal risk to personnel or hardware.