Glenn Contributions to Apollo
The Lewis Research Center (now NASA Glenn), provided important early research as well as subsequent direct technical support to the Apollo program.
In 1958, when he was Associate Director of Lewis, Dr. Abe Silverstein was called to Washington to help organize NASA, which was, as the Successor of National Advisory Committee for Aeronautics (NACA), to be the nation's civilian agency for meeting the challenge of space.
Within the new agency, Dr. Silverstein was appointed the Headquarters Director of Space Flight Programs with responsibility for developing and initiating all space missions.
Among the many missions conceived at that time was a manned journey to the Moon and back. Dr. Silverstein himself named it "Apollo" after one of the most versatile of the Greek gods. Dr. Silverstein recalls he chose the name after perusing a book of mythology at home one evening, early in 1960. He thought that the image of "Apollo riding his chariot across the Sun was appropriate to the grand scale of the proposed program."
When did the program originate? The idea of a lunar mission was first officially introduced at a meeting of NASA program planners in Nov. 1959 at Wallops Island, Va. However between that time and President John F. Kennedy's historic space commitment of 1961, much of the basic mission remained to be worked out. During this time Dr. Silverstein chaired the committee that determined the characteristics of the Saturn family of launch vehicles, including the use of liquid hydrogen-oxygen propellants.
Pioneering Rocket Research
Long before Apollo was ever planned or named, the Lewis Research Center in Cleveland was advancing the propulsion technology that would help make the mission possible.
As early as the latter part of the 1940's, Lewis had begun research on high energy liquid and solid propellants under the direction of Dr. Walter T. Olson. This work included liquid hydrogen and liquid oxygen as a rocket propellant. Initial Lewis investigations of the hydrogen-oxygen propellant combination involved small thrust chambers in the range of 100 to 1000-lbs. thrust. Cooling of the nozzle of these high energy rockets was identified as a major problem. Use of the hydrogen fuel as a coolant was simulated in electrically-heated tubes in which liquid hydrogen flowed. Data from these tests served as design information for hydrogen cooling of rocket engines.
During the 1950's, rocket engineers and scientists experimented with a variety of thrust chamber designs to achieve high combustion efficiency and smooth burning; and they measured heat transfer rates within the thrust chamber and demonstrated how to cool the chamber and nozzle with liquid hydrogen. Since hydrogen, the lightest of the elements, in its liquid state boils at -423 degrees F, and the oxidizer, liquid oxygen, is stored at -297 degrees F, another major concern was how to handle the cryogenic propellants themselves.
By 1958, as the United States entered the space business the Lewis Research Center had tested a fully cooled, liquid hydrogen-liquid oxygen thrust chamber at the large scale of 20,000 lbs. thrust.
A number of Lewis staff members -- by then well experienced in high-energy propulsion systems -- were called upon by NASA Headquarters to serve on the technical assessment teams which recommended the contractor to build the F-l and J-2 engines. Dr. Silverstein chaired the Source Board which made the final selection of the F-l contractor. Work began on the F-l engine, the nation's largest, in 1958 and on the J-2 in 1960.
Propellant Pump Design
During the course of development of these engines, Lewis continued its technical support in the form of consultation with NASA's Marshall Space Flight Center, Huntsville, Ala. Melvin Hartmann and Ambrose Ginsburg, Lewis fluid systems engineers, served on a Marshall committee to review problems being experienced by the F-l turbopump. These and other specialists served as consultants on a J-2 review committee. Among the topics discussed and of particular interest to the Lewis men was the inducer, the component that draws the boiling cold hydrogen into the pumps. Previous research conducted on this component at Lewis' Plum Brook Station near Sandusky helped verify data of the Marshall Center that showed the inducers would permit a desired low pressure in the fuel tank.
Lewis also assisted a Marshall task group in achieving combustion stability in the F-l engine. Dr. Richard Priem, experienced in advanced rocket combustion, was one of this group studying the rocket screaming, a phenomenon caused by strong resonant pressure waves that can destroy a rocket engine in seconds. One other area of consultation with Marshall during the F-1 development was on fabrication of the thrust chamber. Walter Russell, a fabrication specialist served on the committee to review the materials and processes for the fabrication of the furnace-brazed thrust chamber and its jacket.
Staff members also lent their technical knowledge to other areas of the Apollo propulsion systems. Early studies were conducted at Lewis on the type of storable propellants to be carried on the upper stage of the Saturn V vehicle and on the spacecraft.
The Center's unique Zero-Gravity Facility was called upon to do two jobs for the Apollo program. In mid-1960, engineers used this facility to help solve the problem of re- starting the Service Module's propulsion system in space. Using surface tension phenomena observed during these studies, Lewis engineers assisted in designing a retainer for the propellant in the fuel tank. This retainer would keep enough propellant at the bottom of the tank to ensure that propellant would enter the pump and re-start the engine.
The Zero-Gravity Facility was used to help solve a similar problem in the S-IVB third stage of the Saturn V for the Marshall Center. In flight when the S-IVB engine shut down, auxiliary hydrogen-peroxide thrusters were turned on to settle the sloshing propellants. During the coast phase the propellants were maintained in the bottom of the fuel tank by the thrust obtained when boiled off hydrogen gas was ducted through a small thruster system. Studies in the Zero-G Facility were able to determine the proper size of these various thrusters.
Fuel Cell Performance
One of the astronaut's concerns about how weightlessness in space might affect fuel cell performance drew helpful information from Lewis too. Fuel cells were carried aboard the Service Module to provide electric power to spacecraft systems. Consequently, Lewis researchers investigated this area and made known to the Manned Spacecraft Center (now Johnson) that the condenser of the fuel cell did not depend on gravity to operate properly. Lewis also was asked by Marshall to determine the heat transfer characteristics of the condenser; this information was used in a computer simulation of the spacecraft's electrical power subsystem.
Rocket Engine Combustion
During 1967 Lewis engineers were consulting on the overall combustion and system stability of the Lunar module ascent engine, the critical propulsion system for the Ascent Stage, which returns the astronauts from the moon to lunar orbit. John Wanhainen, a chemical rocket expert, was part of a task group to overcome the high frequency combustion instability noted in the engine. Two other engineers, Robert Dorsch and Leon Wenzel, ran analog computer analyses of low frequency combustion instability characteristics.
Wind Tunnel Tests
The Center's 8 x 6-foot transonic and 10 x 10-foot supersonic wind tunnels were used in extensive tests on models of Saturn booster stages.
The first such tests were made in the late 1950's when engineers studied base flow and heating tests on the SIB booster, the eight-engine first stage of the Saturn I. The 1/45th scale model had real, working rocket engines of 250 lbs. thrust each. Data were taken over a range of speeds from takeoff to Mach 3.5 and of altitudes from sea level to 150,000 feet. This simulation of actual flight conditions provided valuable information on the pressure and heat loads experienced on the base and engines' compartment of the SI vehicle. By varying the size and location of flow deflectors and shroud air scoops-- devices to channel the air to best advantage--engineers were able to minimize the pressure and heating loads. Another study on the SI helped optimize vehicle flight stability and air pressure distribution.
In the 1964-1966 period, base flow and heating also were studied in both wind tunnels for the SI C first stage of the Saturn V. Also, the force required to move the engine nozzles for directional control had to be measured. These measurements helped determine the size of the actuators required to gimbal the engines. In all manned missions, safety of the public, the astronauts, and the operating crew, is a major concern to NASA. In case a mission must be terminated early, one of the first options the astronauts have is to employ the Launch Escape Vehicle and Tower which stands atop the Command Module. This escape system propels the Command Module out and away from the Saturn V. During 1964, tests were made on the system in the Lewis Research Center's 8 x 6 tunnel at the request of the Manned Spacecraft Center. In the tunnel, a model of the escape system attached to the Command Module was released at various angles to determine its stability under simulated flight conditions.
Safety was the subject that brought I. Irving Pinkel, former Lewis Assistant Director for Aerospace Safety, to serve as a consultant to the Apollo 204 Review Board. In that capacity and as a member of the team which investigated the causes of the spacecraft fire which took the lives of three astronauts early in 1967, Pinkel helped to recommend changes in the capsule to prevent a future tragedy.
Through extensive consulting on fracture mechanics, Lewis professionals have assisted in improving the more than 140 pressure vessels of the Saturn V, and the SII fuel tank. Particular contributions by Lewis materials scientists to the construction of pressure vessels included improved test methods, and methods of design and analyses used on new concepts in fracture mechanics technology. Other materials scientists and engineers provided fracture research data on the critical weldments of the SII fuel and on the tank material itself; they also recommended cryogenic proof tests, and suggested flight conditions to reduce wind loads on the vehicle.