Aerospace Vehicle Entry Flightpath Control

Aerospace

Aerospace Vehicle Entry Flightpath Control (TOP2-303)

Control System that can be feasibly integrated with a Deployable Entry Vehicle (DEV)

Overview

The state-of-the-art in hypersonic entry Guidance and Control (G&C) is traditionally based on rigid entry vehicles, like the Orion capsule, Space Shuttle, etc., that use a Reaction Control System (RCS) to control the bank angle of the vehicle. However, for future high mass missions to Mars, advancements in hypersonic aerospace vehicle design, and evolving science goals, are stretching the performance capabilities of traditional entry systems. NASA’s Pterodactyl team at Ames Research Center has developed a novel yaw-to-bank control system for a non-traditional vehicle configurations, such as a Deployable Entry Vehicle (DEV) that can be folded and stowed. The approach provides vehicle stabilization, steering, and precise targeted landing. This control architecture is agnostic to control actuators and can be used with any aerospace vehicle with a strong dihedral effect and/or different guidance control variables.

The Technology

This novel flightpath control system exploits the dihedral effect to control the bank angle of the vehicle by modulating sideslip (Figure 1). Exploiting the dihedral effect, in combination with significant aerodynamic forces, enables faster bank accelerations than could be practically achieved through typical control strategies, enhancing vehicle maneuverability. This approach enables vehicle designs with fewer control actuators since roll-specific actuators are not required to regulate bank angle. The proposed control method has been studied with three actuator systems (figure below), Flaps Control System (FCS); Mass Movement Control System (MMCS); and Reaction Control System (RCS). • FCS consists of a flap configuration with longitudinal flaps for independent pitch control, and lateral flaps generating yaw moments. The flaps are mounted to the shoulder of the vehicle’s deployable rib structure. Additionally, the flaps are commanded and controlled to rotate into or out of the flow. This creates changes in the vehicle’s aerodynamics to maneuver the vehicle without the use of thrusters. • MMCS consists of moveable masses that are mounted to several ribs of the DEV heatshield, steering the vehicle by shifting the vehicle’s Center of Mass (CoM). Shifting the vehicle’s CoM adjusts the moment arms of the forces on the vehicle and changes the pitch and yaw moments to control the vehicle’s flightpath. • RCS thrusters are mounted to four ribs of the open-back DEV heatshield structure to provide efficient bank angle control of the vehicle by changing the vehicle’s roll. Combining rib-mounted RCS thrusters with a Deployable Entry Vehicle (DEV) is expected to provide greater downmass capability than a rigid capsule sized for the same launch

Multiple, independent control system configurations

Benefits

Enables the successful integration of non-propulsive control systems to realize vehicle configuration benefits that include: reductions in propellant mass requirements, net mass savings for the vehicle, and enhanced maneuverability from faster banking accelerations than possible with traditional systems.
Provides a flexible control architecture applicable to: - aerospace vehicles flying subsonic, supersonic, and hypersonic flight speeds - different types of control actuators (e.g. MMCS, FCS, RCS, etc.)

Applications

Aerodynamic bodies that require deployable control surfaces on articulating bodies
Guidance and Control (G&C) of Deployable Entry Vehicles (DEVs) with high precision
Precision landing of small payloads sent from planetary bodies back to Earth (e.g., biological samples landed near scientific facilities), and (2) increasing down-mass capabilities to planetary bodies such as Mars
Reentry vehicles and precision space launched or ballistic munitions industry

Download Fact Sheet as a PDF

Ask a Question

Apply to License

Technology Details

Category Aerospace

Reference Number TOP2-303

Case Number(s) ARC-18469-1

Patent(s) (pop-up blockers must be disabled) 11,772,828

Attachments

Papers D’Souza, et al., “Pterodactyl: System Analysis of an Asymmetric and Symmetric Deployable Entry Vehicle for Precision Targeting Using Flaps,” https://doi.org/10.2514/6.2021-0762.

Alunni, et al., “Pterodactyl: Trade Study for an Integrated Control System Design of a Mechanically Deployed Entry Vehicle,” https://doi.org/10.2514/6.2020-1014.

Okolo, et al., “Pterodactyl: Development and Comparison of Control Architectures for a Mechanically Deployed Entry Vehicle,” https://doi.org/10.2514/6.2020-1012.

Johnson, et al.,“Pterodactyl: Development and Performance of Guidance Algorithms for a Mechanically Deployed Entry Vehicle,” https://doi.org/10.2514/6.2020-1011.

Tags:

atmospheric entry control systems re-entry precision landing entry vehicle G&C system aerodynamic control non-propulsive deployable guidance and control flap control system flexible propellant (and fuel) flow lines articulating structure thruster reaction control system precision landing deployable entry vehicle center of mass manipulation moveable ballasts entry descent landing (EDL)

Similar Results

First stratospheric balloon demonstration

Multistage Free-Flight Testing System

The disclosed technology provides a multistage system for evaluating the free-flight behavior of test articles across of the supersonic, transonic, and subsonic regimes. First, a drop platform is lifted to high altitudes using a lifting device, such as a stratospheric balloon. The drop platform houses multiple projectiles, each containing an ejection mechanism, an on-board avionics suit, and an instrumented test article. Upon reaching the target altitude via the lifting device, the drop platform releases the projectiles sequentially. Each projectile accelerates to a target speed and altitude before ejecting its test article into the freestream. The test articles, such as a scaled re-entry capsule, then collect flight data during their descent through the various Mach regimes, providing valuable insights into their flight performance under mission-relevant conditions. This innovative testing system offers several benefits. It enables the simultaneous testing of multiple vehicles, facilitating the evaluation of design variations as well as statistical analyses of vehicle behavior. This system also provides significant cost savings in comparison to other state-of-the-art testing methods, such as ballistic range testing. Additionally, the test articles within each projectile are easily interchangeable through a simple, modular change of a support surface in the ejection mechanism. This flexibility enables the system to accommodate a range of other aerodynamic technologies, including other vehicles, parachutes, propulsion systems, and defense technologies. This system can enhance the efficiency and robustness of reentry vehicle design, testing, and simulation operations through the collection of rich, flight-relevant data.

Co-Optimization of Blunt Body Shapes for Moving Vehicles

Vehicles designed for purposes of exploration of the planets and other atmospheric bodies in the Solar System favor the use of mid-Lift/Drag blunt body geometries. Such shapes can be designed so as to yield favorable hypersonic aerothermodynamic properties for low heating and hypersonic aerodynamic properties for maneuverability and stability. The entry trajectory selected influences entry peak heating and integrated heating loads which in turn influences the design of the thermal protection system. A nominal is used to compare each shape considered. The vehicle will be subject to both launch and entry loading along with structural integrity constraints that may further influence shape design. Further, such vehicles must be sized so as to fit on existing or realizable launch vehicles, often within existing launch payload shroud constraints.

Supersonic Laminar Flow Control

This technique injects precisely defined stationary transient growth disturbances into the free air slipstream over a wing that develop into streamwise elongated "streaks." These streaks are created with an alternating pattern of low and high streamwise velocity in the boundary layer flow adjacent to the aerodynamic surface of interest. Judicious selection of streak wavelength, amplitude, and profile allows the first-mode instability waves responsible for transition via oblique mode breakdown to be damped while the remaining, uncontrolled waves are kept below an amplification threshold. A similar control concept is also applicable to second mode transition at hypersonic Mach numbers.

Transformable Hypersonic Aerodynamic Decelerator

The invention allows the deployment of a large aerodynamic decelerator relative to the size of its launch vehicle, which is controllable and can be transformed into a landing system. A structure composed of a radial assembly of ribs and struts in a four bar linkage arrangement fits inside a launch vehicle shroud, expands into a deployed size, and permits rotation about a pivot point along the vehicle axis. The mechanism that deploys the decelerator surface, doubles as the actuation/control mechanism, and triples as the payload surface leveling system. The design permits the use of conformable thermal protection systems at the central part and a flexible TPS, 3-D woven carbon fabric, as skin in the majority of the regions of the aeroshell entry system. The fabric handles both the heat and mechanical load generated during entry. This system is very mass competitive with other lightweight systems such as inflatable and rigid decelerators and is believed to be more reliable and testable at sub-scale. Once the payload reaches its destination, the decelerator structure leverages atmospheric drag to slow the craft from hypersonic travel speeds to an appropriate landing velocity. The decelerator can be actuated during descent to generate lift and steer the payload to its intended destination. Retro propulsion engines provide the final deceleration just before landing, and the decelerator structure is inverted to act as a landing platform and help minimize the impact of landing load.

Improving VTOL Proprotor Stability

Proprotors on tiltrotor aircraft have complex aeroelastic properties, experiencing torsion, bending, and chord movement vibrational modes, in addition to whirl flutter dynamic instabilities. These dynamics can be stabilized by high-frequency swashplate adjustments to alter the incidence angle between the swashplate and the rotor shaft (cyclic control) and blade pitch (collective control). To make these high-speed adjustments while minimizing control inputs, generalized predictive control (GPC) algorithms predict future outputs based on previous system behavior. However, these algorithms are limited by the fact that tiltrotor systems can substantially change in orientation and airspeed during a normal flight regime, breaking system continuity for predictive modeling. NASA’s Advanced GPC (AGPC) is a self-adaptive algorithm that overcomes these limitations by identifying system changes and adapting its predictive behavior as flight conditions change. If system vibration conditions deteriorate below a set threshold for a set time interval, the AGPC will incrementally update its model parameters to improve damping response. AGPC has shown significant performance enhancements over conventional GPC algorithms in comparative simulations based on an analytical model of NASA’s TiltRotor Aeroelastic Stability Testbed (TRAST). Research for Hardware-In-the-Loop testing and flight vehicle deployment is ongoing, and hover data show improved vibration reduction and stability performance using AGPC over other methods. The example presented here is an application to tiltrotor aircraft for envelope expansion and vibration reduction. However, AGPC can be employed on many dynamic systems.