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Moeckel, W. E.

Publications and source records attributed to Moeckel, W. E..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

A thrust-sheet propulsion concept using fissionable elements

A space propulsion concept is proposed and analyzed which consists of a thin sheet coated on one side with fissionable material, so that nuclear power is converted directly into propulsive power. Thrust is available both from ejected fission fragments and from thermal radiation. Optimum thicknesses are determined for the active and substrate layers. This concept is shown to have potential mission capability (in terms of velocity increments) superior to that of all other advanced propulsion concepts for which performance estimates are available. A suitable spontaneously fissioning material such as Cf-254 could provide an extremely high-performance first stage beyond earth orbit. In contrast with some other advanced nuclear propulsion concepts, there is no minimum size below which this concept is infeasible.

Moeckel, W. E.↗
NASA NTRS1976

A thrust-sheet propulsion concept using fissionable elements

A space propulsion concept is proposed and analyzed which consists of a thin sheet coated on one side with fissionable material, so that nuclear power is converted directly into propulsive power. Thrust is available both from ejected fission fragments and from thermal radiation. Optimum thicknesses are determined for the active and substrate layers. This concept is shown to have potential mission capability (in terms of velocity increments) superior to that of all other advanced propulsion concepts for which performance estimates are available. A suitable spontaneously fissioning material such as Cf254 could provide an extremely high-performance first stage beyond earth orbit. In contrast with some other advanced nuclear propulsion concepts, there is no minimum size below which this concept is infeasible.

Moeckel, W. E.↗
NASA NTRS1975

Optimum exhaust velocity for laser-driven rockets

The laser-driven rocket in which remotely generated laser power is used to heat propellant belongs basically to the class of specific-impulse limited propulsion systems if difficult missions are considered. It was previously established that trip time reaches a minimum as specific impulse is varied for payload transfers from low earth orbit to synchronous orbit and return via laser-driven rocket propulsion, the computations being based on the perigee-propulsion laser drive described by Minovitch (1972). The present study shows that such minimum occur for all missions and that optimum specific impulse is primarily determined by the mission difficulty. More generally, this optimum specific impulse maximizes payload kinetic energy achievable with a fixed jet power and propulsion time. A formula relating propulsion time parameter to payload ratio is obtained for estimating mission capabilities of laser-driven rockets.

Moeckel, W. E.↗
NASA NTRS1972

Comparison of advanced propulsion concepts for deep space exploration.

Equations and charts are presented which permit rapid estimation of propulsion system performance requirements for some typical deep space missions. The simplicity results from use of gravity-free equations of motion, which are shown to yield good approximations to trip times obtained with solar gravity and planetary motion included. The agreement is satisfactory for missions that do not enter or depart from low orbits about the major planets. A number of advanced propulsion concepts for which performance estimates are available are compared with respect to their capability for fly-by, rendezvous, and round-trip planetary missions. Based on these estimates, the gas-core nuclear fission rocket and the pulsed fusion rocket yield the fastest trip times to the near planets. For round trips to Jupiter and beyond, the controlled fusion rocket shows progressively superior capabilities. Several propulsion concepts based on use of impinging laser beams are found to be noncompetitive with the other advanced concepts for deep space missions.

Moeckel, W. E.↗
NASA NTRS1972

Propulsion by impinging laser beams.

Evaluation of the best mission performance of a 'photon sail' system using an impinging laser beam. The results of calculations of nondimensional time history of distance, velocity, and acceleration for propulsion by laser beam reflection are presented. These calculations show that propulsion by impinging laser beams is not competitive with advanced onboard propulsion concepts for missions in the solar system.

Moeckel, W. E.↗
NASA NTRS1972

Comparison of advanced propulsion concepts for deep space exploration

Equations and charts are presented that permit rapid estimation of propulsion-system performance requirements for some typical deep-space missions. A number of advanced propulsion concepts for which performance estimates are available are compared with respect to their capability for flyby, rendezvous, and roundtrip planetary missions. Based on these estimates, the gas-core nuclear fission rocket and the pulsed fusion rocket yield the fastest trip times to the near planets. For round trips to Jupiter and beyond, the controlled fusion rocket shows progressively superior capabilities. Several propulsion concepts based on use of impinging laser beams are found to be noncompetitive with the other advanced concepts for deep space missions. Requirements for attainment of interstellar distances within a human lifetime are found to be some orders of magnitude beyond the capabilities of any propulsion concepts for which performance estimates are now possible.

Moeckel, W. E.↗
NASA NTRS1963

Electric propulsion.

Principles of electric propulsion, its development for space missions and systems for generating electric power

SPACECRAFT PROPULSION↗
NASA NTRS1963

Electric propulsion

Benefits of electric propulsion systems for lunar and interplanetary flight

LUNAR FLIGHT↗
NASA NTRS1961

Fast Interplanetary Missions with Low-Thrust Propulsion Systems

A simple family of indirect-transfer trajectories between circular orbits is used to evaluate the mass ratio required to complete round-trip interplanetary missions using low-thrust propulsion systems. These trajectories, although not optimum, yielded very substantial reductions in total round-trip time for Mars missions with moderate increases in initial weight. For a powerplant specific weight a of 10 pounds per kilowatt of jet power, trip times were reduced from 1200 to 600 days, for a typical manned mission, with an initial weight increase of a factor of two. Comparison with a nuclear rocket with 1000-second specific impulse indicated that the electric-propulsion system required less initial weight for trip times as low as 550 days with alpha equal to 10 and as low as 400 days with alpha equal to 5 pounds per kilowatt. Further weight reductions would be expected with more nearly optimum trajectories.

Moeckel, W. E.↗