Engineering topics

Litton, Daniel K.

Publications and source records attributed to Litton, Daniel K..

4 records

NASA NTRS2017

Launch Vehicle Ascent Trajectory Simulation Using the Program to Optimize Simulated Trajectories II (POST2)

The Program to Optimize Simulated Trajectories II (POST2) has been continuously developed for over 40 years and has been used in many flight and research projects. Recently, there has been an effort to improve the POST2 architecture by promoting modularity, flexibility, and ability to support multiple simultaneous projects. The purpose of this paper is to provide insight into the development of trajectory simulation in POST2 by describing methods and examples of various improved models for a launch vehicle liftoff and ascent.

Lugo, Rafael A.↗

NASA NTRS2013

Progress in Payload Separation Risk Mitigation for a Deployable Venus Heat Shield

A deployable decelerator known as the Adaptive Deployable Entry and Placement Technology (ADEPT) offers substantial science and mass savings for the Venus In Situ Explorer (VISE) mission. The lander and science payload must be separated from ADEPT during atmospheric entry. This paper presents a trade study of the separation system concept of operations and provides a conceptual design of the baseline: aft-separation with a subsonic parachute. Viability of the separation system depends on the vehicle's dynamic stability characteristics during deceleration from supersonic to subsonic speeds. A trajectory sensitivity study presented shows that pitch damping and Venusian winds drive stability prior to parachute deployment, while entry spin rate is not a driver of stability below Mach 5. Additionally, progress in free-flight CFD techniques capable of computing aerodynamic damping parameters is presented. Exploratory simulations of ADEPT at a constant speed of Mach number of 0.8 suggest the vehicle may have an oscillation limit cycle near 5 angle-of-attack. The proposed separation system conceptual design is thought to be viable.

Smith, Brandon P.↗

NASA NTRS2011

Inflatable Re-entry Vehicle Experiment (IRVE-4) Overview

The suite of Inflatable Re-Entry Vehicle Experiments (IRVE) is designed to further our knowledge and understanding of Hypersonic Inflatable Aerodynamic Decelerators (HIADs). Before infusion into a future mission, three challenges need to be addressed: surviving the heat pulse during re-entry, demonstrating system performance at relevant scales, and demonstrating controllability in the atmosphere. IRVE-4 will contribute to a better understanding of controllability by characterizing how a HIAD responds to a set of controlled inputs. The ability to control a HIAD is vital for missions that are g-limited, require precision targeting and guidance for aerocapture or entry, descent, and landing. The IRVE-4 flight test will focus on taking a first look into controlling a HIAD. This paper will give an overview of the IRVE-4 mission including the control response portion of the flight test sequence, and will provide a review of the mission s development.

Litton, Daniel K.↗

NASA NTRS2011

Reverse Launch Abort System Parachute Architecture Trade Study

This study investigated a potential Launch Abort System (LAS) Concept of Operations and abort parachute architecture. The purpose of the study was to look at the concept of jettisoning the LAS tower forward (Reverse LAS or RLAS) into the free-stream flow rather than after reorienting to a heatshield forward orientation. A hypothesized benefit was that due to the compressed timeline the dynamic pressure at main line stretch would be substantially less. This would enable the entry parachutes to be designed and sized based on entry loading conditions rather than the current stressing case of a Pad Abort. Ultimately, concerns about the highly dynamic reorientation of the CM via parachutes, and the additional requirement of a triple bridle attachment for the RLAS parachute system, overshadowed the potential benefits and ended this effort.

Litton, Daniel K.↗