Can We Catch Up In Rocket Research?

by E J Tangerman, McGraw-Hill Representative
at White Sands Rocket Tests
An eye-witness account of V-2 and WAC Corporal launchings points up need for continued research and development in guided missile program – especially important in view of atomic developments.

It has been but a remarkably short time since a workaday reporter could have a terrifying day by going to Aberdeen Proving Grounds to watch the firing of a 16-in gun. But then American military science caught up with — and passed — Buck Rogers with the Bazooka, Super-Bazooka, Mousetrap, Minnie Mouse, Holy Moses, Tiny Tim, Xylophone, Calliope, Grand Slam, Woofus, Whiz Bang, Honeycomb and Snake; all innocent-sounding names for super-lethal rockets and rocket launchers. But the most spectacular rocket of all still is the Nazi V-2, which was demonstrated for some 40 newsmen, photographers and movie cameramen — and again as many top military men — at White Sands Proving Ground, NM, on May 10.

Curiously enough the rocket is not a new weapon, but a modernized one. The Chinese launched rockets against the Mongols in 1232; rockets were a terrorizing weapon in Europe 100 yr later. Cannon outmoded then — until native Indian troops used them against the British toward the close of the 18th century. Following traditional military procedure, the British developed rockets of their own, and used them against Napoleon and against Fort McHenry in Baltimore to help a certain poet named Key write the "Star Spangled Banner." Only 32 yr later — 100 yr ago — the United States Army created its first rocket battery. We used pinning rockets against Mexico at Vera Cruz and in storming Chapultepec, then gave them up. The rise of the airplane in World War I suggested rockets again, but it was not until World War II that they came back — and with a vengeance.

"Vengeance" was the word that gave the German A14 rocket its propaganda title "V-2". It differs from military predecessors in being liquid-fueled, and in being far larger. Our largest rocket, the WAC Corporal, is a foot in diameter, 16' long, and weighs 700 lb at launching; the V-2 is 5' in diameter, 46' long and weighs 28,000 lb. (Its powerplant was analyzed in detail in last month's Aviation — p 63 — by Ray Healy, AAF rocket consultant.) As a weapon, the V-2 was of limited strategic significance — it was very costly considering its small payload, limited range and accuracy. But the development of the atomic bomb changes the picture; now development of accurate long-range missiles is of extreme importance. Literally, the sky is the limit, for the Ordnance Dept is building test equipment for rockets ten times as big as the V-2 — a temptation for designers to devise them. And consider for a moment the production from only one German plant — the underground unit at Nordhausen — which turned out 900 V-2s per month. With atomic warheads, they'd have been vengeance weapons and no mistake.

The V-2 was no sudden development; it took 12 yr by the best available German scientists and millions of dollars. We are now capitalizing on this work to obtain fundamental information which will help us develop better, longer-range missiles. To speed the job, we brought over parts for some 25 V-2s and placed in "protective custody" a number of German scientists connected with guided-missile research for over ten yr at Peenemunde. These scientists are now working quietly at White Sands indexing and translating captured documents (thank goodness, the methodical Germans record everything), identifying rocket material, assisting in assembling and firing V-2s, and providing technical information on rocket design. They have also assisted in training the detachments assigned for handling, firing and tracking the rockets, and in setting up portions of the elaborate system of synchronized radio, radar, photographic and visual equipment used to observe and record the behavior of the rockets in flight. These scientists are under contract for a limited period, their nominal salaries going to their families in Germany. They are allowed no access to our own classified projects, and leave their designated area only with military escort. Those I talked to were happy as clams with their giant toys, and would like to stay here.

To assemble the V-2s, replace missing parts, repair damaged ones and provide fuels, General Electric has been employed. This permits a variety of additional test objectives, including testing of alternate components, use of radar in tracking and in countermeasures, developing of instrumentation and studying of trajectories, upper-atmosphere physics and the like.

To accomplish these objectives, the warhead of the V-2, with its explosive filling, becomes a "peacehead" filled with scientific paraphernalia for exploring the upper atmosphere and for evaluating the performance of the propulsive system and automatic controls of the rocket. The fuel supply used by the Nazis to fire rockets into London from launching areas more than 200 miles away on the continent, over a trajectory reaching a height of 60 miles, can, when the automatic controls are set properly, send them up to twice that height in a very nearly vertical trajectory ending in a safe impact area within the Proving Ground.

In current tests the height attained will be about 100 mi. The V-2 launched May 10 went 72 mi (427,000 yd) high and landed 30 mi from the firing point. Fuel remaining when burning was terminated by remote control exploded on impact, gouging out a hole 20 ft deep and 30 ft across and burying the head in hard clay and gypsum sand. Actually, the 10 tons of fuel in a V-2 has more energy content than its 1800-lb warhead by many times, even the remainder frequently matching the warhead in power. Lateral error was only 340 yd, or about 0.5%.

As fired against London, about 14,000 lb of gas expelled at an average velocity of 6800 fps gave about 10,000 lb of rocket and unburned propellants a forward velocity of 4900 fps when the fuel supply was cut off and burning ceased. This happened about 60 sec after takeoff when the rocket had traveled 25 mi along its trajectory and was moving in a direction 47° away from the vertical, ie, 43° above the horizontal, at a point 17.5 mi above the ground and 15.5 mi longitudinally from the launcher. The normal trajectory started the fourth second, fuel was cut off at 67 sec and 3,440 mph, 22 mi from the launcher and 24 mi in the air. Maximum elevation of 50.8 mi was reached at 176 sec and 147 mi and impact was at 306 sec and 182 mi. This takes the V-2 through the troposphere (to 40,000 ft), the stratosphere (40,000 to 270,000 ft) and into the Heaviside layer (270,000 to 320,000 ft.) The May 10 shot went beyond the ionosphere, establishing an American record of 360,000 ft.

During the burning period, direction of the rocket is controlled by the action of four movable vanes on the fins and four graphite ones in the jet — the latter essential during the low-velocity starting period when the fin vanes have no aerodynamic effect. Vanes 1 and 3 in both groups are in tandem to control roll and yaw. Vanes 2 and 4 in the jet path control pitch, while fin vanes 2 and 4: act as stabilizers. The 1 and 3 vanes and stabilizers 2 and 4 (independently motored) are controlled by a gyroscope to maintain the axis of the rocket in the vertical plane through the launching and target points, thus keeping the rocket heading in the right direction.

Jet vanes 2 and 4 are controlled by another gyroscope to produce and maintain correct inclination of the trajectory during the burning period. This second gyroscope is subject to the control of a third gyroscopic system, the real brains of the missile, which serves to maintain vertical travel to a height of about one mi, then to tilt the rocket slowly away from the vertical until it travels on the desired course, thereafter to maintain this course until the velocity is correct for the range desired, and finally, to cut off the fuel supply at that velocity. thus ending propulsion. Fuel cutoff can also be accomplished by remote control from the ground. After jet propulsion has ceased, the rocket behaves like a projectile fired with the same speed and direction from a gun.

The rocket rises vertically at first, and slowly, but travels ever faster (max acceleration 6G) until about a minute later it reaches the cutoff value over 3,000 mph %#151; nearly five times the velocity of sound. The jet flame which helped to keep it in sight ceases and it is lost to view. It is terrifying to watch even from 1,000 ft distance, because it soon appears to be directly overhead, and air currents disarrange the smoke generated at fuel cutoffs. You assume flight is erratic.

Seventeen triangulated checking stations are used in tracking V-2, with which four different tracking methods were used May 10: radar, optical, photo, and sonic (Doppler). The radar methods involve radar impulses from a unit in the nose and reflections from three tail surfaces. Both optical and photo (the latter for record) are achieved with an ingenious German instrument, the Askino theodolite, set up 8 to 10 mi from the launching site. The unit has a tremendous lens, which enables two operators to watch the V-2 for 150 mi visually. A built-in camera records the action at 60 frames per sec. Three of these instruments at widely separated points permit checking of roll of the projectile by showing the special pattern painted on it.

Newly developed radio beacons, which contain their own power supply and are actually miniature radio receiver-transmitters, have been fitted into the V-2 "peacehead" for one tracking device. Antenna are in plastic housings on fins. During flight, the receiver is triggered from a ground radar set by pulses which cause the transmitter to repeat the pulses to the radar. This permits the trajectory to be recorded photographically. The Signal Corps radar set used is modified from a unit developed during the war for detecting hostile aircraft and directing anti-aircraft guns.

Conventional radar equipment also tracks the V-2 for its entire flight without the aid of beacons. As the V-2, as fired on London, contained no electronics guiding equipment, emissions of which might be tracked, this method simulates detection of rockets fired by an enemy.

The V-2 is set for firing by an ingenious elevating boom, designed in Germany for that purpose. It is known as the Meiller Wagon, and is long enough to carry the V-2 with ease and set it into place by means of its self-contained, motor driven, hydraulic lifting system. It is equipped with plat- forms which swing into place, enabling workmen to climb up its built-in ladders to make final tests and adjustments after the rocket is in place for firing. It also carries feed lines for some fuels and stabilizes the V-2 until it is ready to fire. (Other rockets are placed by a 60-ft high crane which operates on wide rails north of the launching platform. On this 1,000 ft of track is also a rail launcher developed by the Germans for the V-2).

Also shown correspondents at the White Sands test was the WAC Corporal, an all-American design rocket. The WAC Corporal is a liquid-propelled missile — unlike many solid-fuel types developed at Caltech in a program sponsored by the Ordnance Dept.

The Corporal differs from the V-2 in more than size — it's 1' in diam., 16' long and weighs 700 lb at launching — for it has no control system except three stabilizing fins.

It is launched vertically from a triangular 100' launching tower, and thereafter goes its own merry way, affected by wind, earth rotation and its own peculiarities. These characteristics suggest some of the reasons for the female appellation of WAC the Corporal coming from the fact that some Army rocket projects are designated by familiar ranks. Suffice it to say, officers in charge of the May 10 test (all married men by the way) were so uncertain of its actions that they kept all observers at the very respectful distance of six mi. Indications were that it — or the two principal parts into which it breaks when its fuel tanks collapse as it reenters the atmosphere, fell into the desert five mi the other way, but it appeared to be right over this reporter's shrinking scalp when it vanished on its way up.

The WAC also differs from the V-2 in having different chemicals to power pumps which feed propellants to the combustion chamber and in being "boosted" during its first few seconds of flight by a powerful, short-duration solid-fuel step rocket. This brings the WAC to supersonic speed in 0.6 sec, then falls away to let the WAC motor carry on alone. Judging by its actions and by the appellation Tiny Tim which officers let slip, this step rocket is a variant of the giant rocket which made a fighter plane able to hurl at an enemy target more high explosive than is carried in a salvo from a light cruiser. Tiny Tim was the first multiple-grain American rocket, having four dry-extruded ballistite grains, each weighing some 40 lb. Its original war head was 150 lb of TNT.

Presumably, the launching tower could be tilted slightly to "aim" the WAC and payload limitations are believed to be sufficiently large to carry an atomic warhead, but primary present development is to make the WAC a vehicle to carry meteorological instruments into the stratosphere. In tests at White Sands last October, the WAC reached an altitude of 230,000 ft, or 43.5 mi. This elevation was assumed to have been attained in the May 10 test, although radar tracking failed at 55,000 ft because the rocket was too small to track further by radar.

The WAC costs about $50,000 to make in this country. This could undoubtedly be cut considerably in mass production, but the WAC will probably be discarded in favor of models now under development. The WAC Sergeant (to anticipate a name as well as to conjecture about characteristics) will probably be thinner-shelled and generally lighter in details, hence able to match the V-2 in altitude and may also carry a higher payload. But officials developing it aren't talking.

Both the V-2 and the WAC will be used to carry instruments into the upper atmosphere in future tests. These will measure temperatures, densities and pressures, make spectographic records, count cosmic rays, take samples of gases, dust and bacteria (if these reach such heights).

Still other measurements are being suggested by scientists from all over the country, indicating that some will be disappointed or more and bigger rockets will be required. Officers conducting the tests also want to make some measurements of their own. Skin temperatures, action of control vanes on the V-2 and their effect where there is no atmosphere for them to act upon are among them.

It is known, for example, that the V-2 does not fall with its axis parallel to its trajectory, until it reenters the atmosphere. For some period after its propulsive power is expended and the earth's gravitational pull begins to pull it back, the V-2 remains in its final up-tilted position. Control gyros may activate vanes, but nothing can happen until the vanes have some air against which to push. Then aerodynamic surfaces again become effective.

Skin temperature is estimated to rise to about 600 C (1,300 F) when atmospheric friction decelerates it from its top speed of 3,500 mph to 2,600 mph before it strikes. Enough of this heat is transmitted to the control chamber that plywood dividers there are scorched. This is of course a problem in instrumentation as well. Scientists thus have three choices:

  1. To produce instruments which can stand the shock of striking the earth, the heat of deceleration, and possible explosion of remaining fuels.
  2. To use instruments that broadcast to ground recording devices.
  3. To devise instrument carriers that will throw them out after desired records are obtained, then parachute them safely to earth.
  • Of these three, the third appears most advisable, but presents several serious difficulties. What cover material will withstand ejection shock and frictional heat? How can speed be reduced safely, when a conventional parachute will not open where there is no air and would promptly burn anyhow when air friction is encountered at supersonic speed? The parachute could be forced open by an inflatable rim tube operated by a com- pressed-air bottle, but the heat problem remains. One solution might be to eject the instrument container backward with sufficient force to counteract enough of the rocket's forward speed so skin temperatures stay low. Another is to use metal vanes instead of a 'chute.

    Incidentally, there have been frequent press reports of offers by individuals to ride within a V-2 at their own risk. These are true — I read one letter from a sane and responsible New England man of some prominence, who has developed a pressure suit. The V-2 could readily carry him, and the 6G maximum acceleration never approaches the 8 or 9G at which men "black out," so getting him up there would be simple. But how can he be ejected and decelerated without burning to a cinder? And if he stays within the rocket until close above the earth, how can he endure the inside temperature?

    Meanwhile, the V-2 provides 20 channels for sending back radio and radar records of its flight. These will be used to examine to the greatest possible extent the outer reaches of the earth's envelope, where cosmic rays and shooting stars abound, beyond the fringes of the atmosphere which acts as a filter for such visitors from interstellar space. Our present knowledge is limited to distances of only 19 mi above the earth — the V-2 and the WAC to-be may make it possible for us to reach out to 150 mi — or eight times as far.

    This article was originally published in the June, 1946, issue of Aviation magazine, vol 45, no 6, pp 40-41, 148-150.
    The original article includes 2 photos.
    One photo credited to Press Assn.

    Photo captions: