Science and Industry

on the World Today

WITH the exciting development of Project Mercury, not much attention has been paid to the fact that this is only one of two major American programs for putting a man into space. The other, the Air Force’s Dyna-Soar project, is worth a good look. Although it resembles NASA’s Mercury to the extent that both involve the rocket launching of a manned vehicle into space, Dyna-Soar represents the next great step forward — putting a man into space not just as a passenger-observer but as a true aerospace pilot, able to control his craft and bring it back for a normal landing at an airfield on the ground.

Such a vehicle will have the greatest military importance, not only for reconnaissance but as a bomber and as an attack plane against hostile satellites. Dyna-Soar will be equally valuable in space exploration as a ferry vehicle, vitally necessary for building, manning, and repairing space stations placed in permanent orbit around the earth.

What may prove to be most important of all, Dyna-Soar leads directly to a still more advanced vehicle, one that is simultaneously an airplane and a space plane, able to take off from the ground like conventional aircraft, fly up to the edge of the atmosphere, and keep right on into space. That is for the future.

The skip-glider

Right now, Dyna-Soar is conceived of as a glider stuck on the end of an ICBM rocket. Once the booster has kicked the vehicle into space and dropped off, the pilot will take over. By manipulating jet impulse units — tiny rockets mounted at various points on the vehicle — the pilot will be able to change the vehicle’s altitude in space, while a rocket booster will enable him to change velocity. Thus he will be able to skip-glide his vehicle along the upper edge of the atmosphere, much as a flat stone skips along the surface of a pond, and proceed for long distances around the earth without going into orbit.

When he is ready to return to earth, the pilot will be able to slow his plane by taking deeper and deeper dips into the atmosphere, until he has cut his speed enough to be able to glide back to earth without burning up from the heat generated by air friction. Obviously, Dyna-Soar’s ability to land normally, instead of its having to be parachuted into the ocean, will be a great asset, since this will permit a vehicle to be used repeatedly, like a conventional airplane.

Dyna-Soar is still two or three years from becoming operational, and although Boeing, the prime constructor, has let some $40 million worth of subcontracts, it has not yet revealed the final specifications. Preliminary sketches show a small, bat-wing aircraft, much like the darts of folded paper that small boys sail across the classroom.

It will apparently be about seventeen feet long and will be built of molybdenum. The landing gear will include novel wire-brush skids, now being developed by Goodyear. The brushes, scrubbing along the ground, will slow and stop the plane on the landing strip, while the large surface area of the wire bristles will help dissipate the heat generated in such a frictional landing.

A number of rockets are under consideration as Dyna-Soar’s booster, but it will probably be a Martin Titan II, an ICBM that uses storable liquid fuel. This will be modified by the addition of fins to compensate for the aerodynamic forces set up by the winged glider mounted on its nose. Dyna-Soar’s own rocket engine will use solid fuel and will serve not only to change speed but as an escape rocket, pulling the glider away from the booster should anything go wrong on the launching pad.

High-speed control

The designers of Dyna-Soar face two major problems. One is providing aerodynamic controls that will enable the pilot to fly the craft in all four speed ranges — subsonic, transonic, supersonic, and hypersonic. (“Hypersonic” is used to describe speeds more than five times the velocity of sound.) At Dyna-Soar’s full 18,000 mph speed, the pressures against the plane would be so great that no ordinary controls could operate.

High speed is also the cause of the other major problem. As Dyna-Soar re-enters the atmosphere at many thousands of miles an hour, its leading edges will glow white-hot from air friction. Unlike the Mercury capsule, Dyna-Soar, as an aerodynamic vehicle, will have no blunt end to slow its entry and absorb heat. It will be covered with a special coating that will be burned away but leave unharmed the insulated layer beneath.

Under consideration is a technique borrowed from auto cooling systems: circulating a cooling liquid through the hottest areas—in this case, those with temperatures above 2400 degrees F. Also proposed is the release of helium in the air stream, which has been found to reduce sharply the friction of air moving over the plane’s surfaces.

The range of Dyna-Soar problems to be solved is reflected in the size of the test program. Some thirty wind tunnels and shock tubes are working on Dyna-Soar. This is the largest such program ever set up for a single project and involves three times the tunnel testing used in developing the experimental X-15 plane now being flown to new speed records. The X-15, incidentally, is being used to test Dyna-Soar controls.

Since no winged vehicle has ever carried a man at the speeds at which Dyna-Soar will fly, the wind tunnel data will have to be backed up with other tests, including some in a test cell big enough to hold a full-scale space glider in a simulated space environment. Starting in the summer, large-scale models of Dyna-Soar shapes were to be dropped from high-flying aircraft. Later, more models, as well as full-size structure sections, will be mounted on Scout rockets and flown at near-orbital speeds. Unmanned test flights will continue after the first full-scale Dyna-Soar is built, using both air drops and booster rockets.

Training the spacemen

While the Dyna-Soar itself is still under test, the Air Force will be training the men to fly it. Next year, air-space crews will start training in a modified F-104, carried aloft and dropped by a B-58 bomber. In powerless flight the F-104 has been found to have the same trajectory and handling characteristics predicted for Dyna-Soar, so it will be a realistic trainer. The Air Force is also planning to expand its Test Pilot School, with a special course for space pilots in which they will study everything from space test methods to the theory of relativity.

Manned flight will begin with a series of air drops, followed by suborbital booster flights — short ones at first, but gradually becoming longer until the plane is making extended skip-glider flights. According to one report, Dyna-Soar will eventually be skipped from Cape Canaveral around South America to Edwards Air Base in California.

Suborbital flights will begin in two or three years; the timetable for the next phase, orbital flight, is more uncertain. Because of air resistance to Dyna-Soar’s shape, there is at present no liquidfuel rocket powerful enough to put it into orbit. Solid-fuel rockets could do it, but at this stage they cannot be used, because it is impossible to control their rate of acceleration; a solid-fuel rocket powerful enough to put a Dyna-Soar into orbit would reach full speed so quickly that a human being could not endure the gravity forces. Dyna-Soar’s orbital flight will have to await the development of the Saturn family of superpowerful liquid-fuel rockets, that will be composed of clusters of smaller units.

From the Air Force point of view, the pay-off will come when Dyna-Soar, successfully flighttested, is equipped with various weapon systems. The plane was originally conceived as a bomber, but it will be equally useful for photographic reconnaissance, or for destroying hostile satellites and supporting and maintaining our own. Eventually a larger Dyna-Soar will be built called DynaMows (for “Manned Orbital Weapons System”), designed especially for military missions.

Military spacecraft

The range of possible military applications for manned, maneuverable spacecraft can be judged from the somewhat bewildering array of research projects now in the works.

Boss-Wedge (“Bomb Orbital Strategic System — Weapon Development Glide Entry”) is a three-year research project to find the best way to develop Dyna-Mows further. Two separate research teams of subcontractors are now working on competitive designs under the overall direction of Boeing.

SLOMAR, a manned vehicle for “Space Logistics Supply, Maintenance and Rescue,” is being developed by seven companies: Northrop, Martin, Douglas, North American Aviation, Lockheed, Convair, and GE. Each is preparing its own designs for spacecraft to carry out these various missions. Designs revealed so far include aerospace planes with long projecting metallic fingers that can be manipulated by remote control for repairing and maintaining space satellites in orbit.

Manned, Maneuverable Surveillance Satellite. The Air Force wants studies on a vehicle to carry up to three men on three-day voyages orbiting around the earth. The vehicle would orbit at the 300-mile level, swooping down at command to 100 miles for detailed reconnaissance.

Manned anti-satellite spacecraft, under study for some time by Lockheed and Hughes, have the opposite tactical function of the SLOMAR vehicles. The design, based on expected 1965 technology, shows a 78-foot plane that would be boosted into space but would have a more complicated design than Dyna-Soar. Arrowhead wings extending aft of the fuselage would be folded inward during the launching, both bracing the structure and reducing its wind resistance. Once in orbit, a maneuvering engine would enable the pilot to bring the craft to within 500 feet of a satellite, which would be located by an optical ranging device. On the return, the wings would be unfolded in the atmosphere and a flight control system would automatically adjust the re-entry path, while an automatic navigation system would guide the plane to base.

Planes without boosters

All these various proposed types I of vehicles would, like Dyna-Soar, be boosted into space by a big rocket. But the Air Force views Dyna-Soar as the first step toward a true aerospace plane that would need no booster but would be capable of taking off from an airfield under its own power.

This would require technological advances not yet achieved. An ingenious propulsion system has been proposed, however, to overcome one major obstacle — the great weight of fuel required to propel a vehicle out of orbit and into space. The space engine would be fueled by a combination of liquid hydrogen and liquid oxygen. For this mixture, which is one of the most powerful rocket propellents known, about eight times as much oxygen is needed as hydrogen.

The plane would take off weighing some 500,000 pounds but carryingonly the liquid hydrogen component of its space fuel. It would climb through the atmosphere on standard engines plus rocket boosters which can be jettisoned. Once at the outer edge of the atmosphere, the plane would go into orbit around the earth, and a scoop in its nose would start collecting the molecules of oxygen and nitrogen that compose the thin air of that region. These molecules would be compressed and liquified in a heat exchanger, using liquid hydrogen as a coolant. The nitrogen, which vaporizes at a lower temperature than oxygen, would then be allowed to escape, leaving only liquid oxygen, ready for the fuel tanks. Thus, the second fuel component, 500,000 pounds of liquid oxygen, could be added after the plane had completed the difficult climb through the atmosphere.

This suggested procedure is still highly speculative. Not only are there major problems to be solved in liquifying the gases aboard a plane in flight, but Dr. Theodore Von Karmen, the noted rocket expert, has expressed doubts as to whether any chemically fueled engine will provide enough kick to permit a vehicle to escape from orbit into space. Dr. Von Karmen suggests that a true aerospace plane will have to be powered by nuclear or nuclearelectric engines. If he turns out to be right, there may still be many years before we are able to board a plane at an airport and fly upward to the moon.