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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1990

Constant propellant use rendezvous scenario across a launch window for refueling missions

Active rendezvous of an unmanned spacecraft with the Space Transportation System (STS) Shuttle for refueling missions is investigated. The operational constraints facing both the maneuvering spacecraft and the Shuttle during a rendezvous sequence are presented. For example, the user spacecraft must arrive in the generic Shuttle control box at a specified time after Shuttle launch. In addition, the spacecraft must be able to initiate the transfer sequence from any point in its orbit. The standard four-burn rendezvous sequence, consisting of two Hohmann transfers and an intermediate phasing orbit, is presented as a low-energy solution for rendezvous and retrieval missions. However, for refueling missions, the Shuttle must completely refuel the spacecraft and return to Earth with no excess fuel. This additional constraint is not satisfied by the standard four-burn sequence. Therefore, a variation of the four-burn rendezvous, the constant delta-V scenario, was developed to satisfy the added requirement.

Hametz, M. E.↗

NASA NTRS2004

The NASA Dryden AAR Project: A Flight Test Approach to an Aerial Refueling System

The integration of uninhabited aerial vehicles (UAVs) into controlled airspace has generated a new era of autonomous technologies and challenges. Autonomous aerial refueling would enable UAVs to travel further distances and loiter for extended periods over time-critical targets. The NASA Dryden Flight Research Center recently has completed a flight research project directed at developing a dynamic hose and drogue system model to support the development of an automated aerial refueling system. A systematic dynamic model of the hose and drogue system would include the effects of various influences on the system, such as flight condition, hose and drogue type, tanker type and weight, receiver type, and tanker and receiver maneuvering. Using two NASA F/A-18 aircraft and a conventional hose and drogue aerial refueling store from the Navy, NASA has obtained flight research data that document the response of the hose and drogue system to these effects. Preliminary results, salient trends, and important lessons are presented.

Hansen, Jennifer L.↗

NASA NTRS2005

The NASA Dryden Flight Test Approach to an Aerial Refueling System

Hansen, Jennifer L.↗

NASA NTRS2007

Automated Aerial Refueling Hitches a Ride on AFF

The recent introduction of uninhabited aerial vehicles [UAVs (basically, remotely piloted or autonomous aircraft)] has spawned new developments in autonomous operation and posed new challenges. Automated aerial refueling (AAR) is a capability that will enable UAVs to travel greater distances and loiter longer over targets. NASA Dryden Flight Research Center, in cooperation with the Defense Advanced Research Projects Agency (DARPA), the Naval Air Systems Command (NAVAIR), the Naval Air Force Pacific Fleet, and the Air Force Research Laboratory, rapidly conceived and accomplished an AAR flight research project focused on collecting a unique, high-quality database on the dynamics of the hose and drogue of an aerial refueling system. This flight-derived database would be used to validate mathematical models of the dynamics in support of design and analysis of AAR systems for future UAVs. The project involved the use of two Dryden F/A-18 airplanes and an S-3 hose-drogue refueling store on loan from the Navy. In this year-long project, which was started on October 1, 2002, 583 research maneuvers were completed during 23 flights.

Jennifer L Hansen↗

NASA NTRS2011

Aerial Refueling Process Rescheduling Under Job Related Disruptions

The Aerial Refueling Scheduling Problem (ARSP) can be defined as determining the refueling completion times for each fighter aircraft (job) on the multiple tankers (machines) to minimize the total weighted tardiness. ARSP assumes that the jobs have different release times and due dates. The ARSP is dynamic environment and unexpected events may occur. In this paper, rescheduling in the aerial refueling process with a time set of jobs will be studied to deal with job related disruptions such as the arrival of new jobs, the departure of an existing job, high deviations in the release times and changes in job priorities. In order to keep the stability and to avoid excessive computation, partial schedule repair algorithm is developed and its preliminary results are presented.

Kaplan, Sezgin↗

NASA NTRS2011

Thermal Design Considerations of the Robotic Refueling Mission (RRM)

The Robotic Refueling Mission (RRM) is a flight demonstration of the tasks required to perform robotic refueling of orbiting spacecraft. RRM will be mounted to an ExPress Adapter Plate (ExPA) for launch and installed onto the International Space Station (ISS) Express Logistics Carrier 4 (ELC4). RRM operations will be conducted using the Special Purpose Dexterous Manipulator (SPDM) robotic arm on the ISS with the ORU/Tool Changeout Mechanism (OTCM) for grasping tools and completing the refueling demonstration tasks. This paper presents the thermal considerations and design of the RRM including the tools required for the tasks.

Gregory, Teri H.↗

NASA NTRSDate not supplied

Parametric Cost Analysis of Refueling Options in Cislunar Space

Over the next several years NASA intends to develop and maintain a sustained human presence in cislunar space and on the surface of the Moon. The sustained lunar presence will then serve as a steppingstone for human missions to Mars. To propel the spacecraft taking humans and cargo to and from the lunar surface and to and from Mars will require on the order of hundreds of tons of propellant. Single-use refueling elements (expendable tankers) may be more cost-effective for smaller campaigns, but as the propellant demand grows, so does the potential for a cost benefit from reusable tankers. The cost of two different architectures for delivering propellant to cislunar space was estimated and compared. The first architecture relies on expendable tankers for propellant delivery while the second architecture reuses every element, including launch vehicle stages. The study determined that if the cost of reusing refueling tankers is consistent with the current state of the art, the expendable refueling architecture is more cost effective. However, refinements of the methods used to estimate launch and tanker reuse costs are needed to provide more precise estimates of the breakeven point.

Daniel J Tiffin↗

NASA NTRS2020

Optimal Low Thrust Orbit Transfers for Space Telescope Refueling at SEL2

The James Webb Space Telescope (JWST), a ten billion-dollar infrared telescope with a 6.5m primary mirror to be launched in 2021, is designed to operate in a Halo orbit around the second Sun-Earth Lagrange point (SEL2) for five to ten years. At that point fuel for station keeping and attitude maneuvers will run out. Refueling missions to JWST, as well as to similar space telescope missions proposed for SEL2, could greatly enhance the “science-per-dollar” value and promote a more sustainable use of space assets. In this paper, we present a novel approach to designing fuel optimal trajectories that will allow the refueling spacecraft to arrive at the SEL2 Halo orbit with maximum final mass (i.e. fuel payload). The low thrust optimal control problem is formulated using an indirect optimization method, leading to a two-point boundary value problem with a bang-bang control structure. We make use of a hyperbolic tangent smoothing technique for performing continuation on the thrust magnitude to reduce the sharpness of the control switches in early iterations and, thus, promote convergence. The problem is posed and solved in the circular restricted three-body problem. In this dynamical system, invariant manifolds exist that can be utilized to reduce fuel consumption. The here presented methodology to this challenging and important problem in astrodynamics demonstrates a significant potential for low-cost refueling mission design.

Woollands, Robyn↗

NASA NTRSDate not supplied

Attitude Dynamics of On-orbit Refueling Configurations

On-orbit refueling is a key enabling technology that will allow a significant increase in the amount of payload mass delivered beyond low-Earth orbit. Despite the potential benefits, there are numerous concerns regarding the operability and scalability of this critical technology. This paper explores the attitude dynamics of two docked spacecraft performing propellant transfer. A vector-dyadic equation is derived to account for the change over time in the mass distribution and the position of the mass center of the stack and moving mass terms omitted in previous literature. Subsequently, the result is applied to two SpaceX-inspired refueling configurations to assess the relative magnitudes of the various terms in the vector-dyadic equation in comparison to the gravity gradient torque.

vector-dyadic equation↗

NASA NTRS1973

A flight study of the use of direct-lift-control flaps to improve station keeping during in-flight refueling

To investigate the effectiveness of fast-acting flaps as direct-lift-control (DLC) devices on a fighter airplane, the aileron servo systems of an F-100C variable-stability airplane were modified to provide symmetrical actuation of the surfaces. Initial flight tests using DLC indicated that the task of formation flying and, hence, in-flight refueling could be eased by actuating the DLC flaps through the conventional control stick, with the degree of improvement depending on the basic stability of the receiver aircraft. Results of refueling approaches and connections with U.S. Air Force tankers indicated a moderate overall improvement in vertical station-keeping performance (approximately 19 percent) and a sizeable overall decrease in receiver airplane motions and control activity (approximately 40 percent) with DLC.

Mcneill, W. E.↗

NASA NTRS1985

F-8 refueling boom ground vibration test

A ground vibration test was conducted on a simulated refueling boom mounted on an F-8 airplane. The ground vibration test was conducted to determine if the refueling boom modal frequencies were close to the airplane frequencies. The data presented in this report include modal frequencies, mode shape data, and structural damping coefficients.

Kahoe, M. W.↗

NASA NTRS1985

A Space Station tethered orbital refueling facility

A planned function of the Space Station is to refurbish and refuel an advanced space-based LO2/LH2 orbit transfer vehicle. An alternative to propellant storage at the station is to use a remote facility tied to the station with a long tether. Preliminary design of such a facility is described with emphasis on fluid transfer and storage requirements. Using tether lengths of at least 300 ft, gravity gradient forces will dominate surface tension in such a system. Although gravity driven transfer is difficult because of line pressure drops, fluid settling over the tank outlet greatly alleviates acquisition concerns and will facilitate vented tank fills. The major concern with a tethered orbital refueling facility is its considerable operational complexity including transport of the OTV to and from the facility.

Fester, D. A.↗

NASA NTRS1986

Tethered orbital refueling study

Objectives are to evaluate the feasibility and limitations of fluid acquisition and transfer under an accleration induced in a tethered orbital refueling facility and to provide conceptual designs. Program tasks consist of recommendation of fluid transfer method and parameters; evaluation of disturbances, fluid motion, and damping; selection of passive devices to augment inherent fluid damping and determination of the resultant envelope of operation; assessment of the effect of tether lengths on hazards; and identification of ground and flight tests necessary to prove the tethered orbital refueling concepts.

Fester, D. A.↗

NASA NTRS1987

Dynamical Considerations for Tethered Orbital Refueling Facility

Report summarizes feasibility study for proposed gravity-gradient-stabilized refueling facility tethered to orbiting station. Includes results of preliminary dynamical analysis of fluid transfer and storage and compares alternative system configurations. Concepts introduced in these documents applied to design problems in more detailed study described in "Propellant Tanks for Tethered Orbital Refueling Facility (MSC-21074).

Abbott, Peter W.↗

NASA NTRS1987

An analysis of bipropellant neutralization for spacecraft refueling operations

Refueling of satellites on orbit with storable propellants will involve venting part or all of the pressurant gas from the propellant tanks. This gas will be saturated with propellant vapor, and it may also have significant amounts of entrained fine droplets of propellant. The two most commonly used bipropellants, monomethyl hydrazine (MMH) and nitrogen tetroxide (N2O4), are highly reactive and toxic. Various possible ways of neutralizing the vented propellants are examined. The amount of propellant vented in a typical refueling operation is shown to be in the range of 0.2 to 5% of the tank capacity. Four potential neutralization schemes are examined: chemical decomposition, chemical reaction, condensation and adsorption. Chemical decomposition to essentially inert materials is thermodynamically feasible for both MMH and N2O4. It would be the simplest and easiest neutralization method to implement. Chemical decomposition would require more complex control. Condensation would require a refrigeration system and a very efficent phase separator. Adsorption is likely to be much heavier. A preliminary assessment of the four neutralization shemes is presented, along with suggested research and development plans.

Kauffman, David↗

NASA NTRS1993

On-orbit refueling

The goal of this program is to increase operational availability of space assets by refueling with an expendable launch vehicle (not the Shuttle) in LEO or GEO. Information is drawn from the on-orbit refueling model, COSEMS model, COMA study, and information provided from the San Antonio Air Logistics Center.

POSPISIL↗

NASA NTRS1992

Manned mission to Mars with periodic refueling from electrically propelled tankers

In a joint study by students from the Ecole Polytechnique Feminine, France, and the University of California, Los Angeles, a mission concept that had the objective of evaluating the feasibility of a non-nuclear, yet fast, manned mission to Mars was considered. Ion-engine propelled tankers are postulated that would provide mid-coarse refueling of LOX and LH2 to the manned ship. The scenario is therefore one of a 'split mission', yet with the added feature that the cargo ships include tankers for mid-course refueling. The present study is a continuation of one first conducted last year. Emphasis this year was on the design of the tanker fleet.

Gogan, Laura↗

NASA NTRS2005

Low Gravity Issues of Deep Space Refueling

This paper discusses the technologies required to develop deep space refueling of cryogenic propellants and low cost flight experiments to develop them. Key technologies include long term storage, pressure control, mass gauging, liquid acquisition, and fluid transfer. Prior flight experiments used to mature technologies are discussed. A plan is presented to systematically study the deep space refueling problem and devise low-cost experiments to further mature technologies and prepare for full scale flight demonstrations.

Chato, David J.↗