Chemistry, Solid Propellants and History J. F. Kincaid The Johns Hopkins University, Applied Physics Laboratory1 Technological developments-chemical, mechanical, physical, and biological-have had a major impact upon the course of history. This paper traces the impact of one chemical technology upon four great turning points in history: the defeat of Napoleon at Waterloo in 1815, the victory of the American fleet under Commodore Dewey in Manila Bay in 1898, the defeat of the German Panzers during the Battle of the Bulge in World War 11, and, finally, the turning point of the Korean War when the North Koreans in their heavy Russian tanks were thrown hack a t Pusan. In each case solid propellant technology played a dominant, although generally unrecognized, role. Waterloo The year was 1815. Only three months earlier Napolron had escaued from the Island of Elba oreanized an Arms of 124.000 men, and prepared to engage theallied armies Gnder Wellington. Although not generally known, the Congreve rocket played a decisive role in the events which set the stage for the Battle of Waterloo. William Congreve, a British ordnance officer, first became interested in rockets after the British forces under Lord Cornwallis (yes! the Cornwallis of Yorktown) were soundly defeated at Seringapatam, India, in 1790. A crude rocket huilt of bqmboo and fueled with black powder played a major role in the Indian victory. When news of the unsuccessful campaign reached Great Britain, Congreve decided to improve the rocket for British use. Within a few years an up-graded weapon appeared, having a range of 3,000 yards and a tail stick for stability in flight. Fitted with an effective incendiary warhead weighing seven pounds, it was capable of setting fire to practically anything combustible. And, indeed it did. It set fire to and destroyed Napoleon's fleet in the Harbor in Bologne, which 'had been assembled during 1806 and 1807 with the intent of invading England. However, Napoleon immediately set about assembling a second fleet of wooden ships and barges at the Harbor of Copenhagen. Again, however, the fleet was destroyed, along with much of the city, ending Napoleon's hopes of invading England by sea. Thus, but for the Congreve rocket, the Battle of Waterloo would likely never have occurred. The decisive battle for the control of Europe might have been fought on British rather than ~ French~ soiL2~ ~ ~ . The solid propellant that drove this fiery weapon for more than one and a half miles was hlnrk nowder first descrihed in European literature by .the ~ n ~ l i monk, s h Roger Bacon, in 1247. Bacon's formula for hlack powder was incredibly had chemistry. Containing 40% KNOs, 30% carbon, and 30%sulfur, i t was terribly out of balance. Much less than half of the fuel would have been consumed. Even today the role sulfur plays is uncertain. A much better formulation is ~~~~~
~~
2KN03
~
+ 2C + S
-
CO + CO? + Np
+ KpS03
This formula containing 78% KN03, 10% carhon, and 12% sulfur is not unlike the black powder which evolved not long after Bacon's time: 75% KN03,15% carhon, and 10%sulfur. Why did Bacon do so poorly? Recall that he did not have the benefit of a "CRC Handhook" and Lavoisier's quantitative chemistry was t o come along five centuries later. Early hlack powder was simply ground to a fine powder. However, it soon became obvious that it was desirable to have 834
Journal of Chemical Education
fast burning powder for side arms, powder burning somewhat more slowly for rifles, and quite slow burning powder for cannons and rockets. This led to a fabrication technique known as "corning." Corning involves the use of fluids, generally a mixture of alcohol and water. This produced a powder which caked and could he crushed and screened t o give fine, medium, and coarse fractions needed for the various applications. The water was frequently supplied hy utilizing the urine of the workers; the urine of a heavy wine drinker being regarded as particularly efficacious. "And the rockets red glare . . ." from the Star Spangled Banner? Francis Scott Key wrote the song in 1812, while a captive aboard a British ship at the siege of Fort McHenry in Baltimore. The rockets which created the red glare were Congreves. Why Ft. McHenry was apparently fireproof in contrast to the hapless fleets of Napoleon a t Bologne and Copenhagen is not known. Possibly i t was because of masonary construction and slate-roofed buildings. Manila Bay It was May 1,1898,530 in the morning. Commodore (later Admiral) George Dewey's flagship had approached t o within 6,000 yards of the Spanish fleet laying in anchor in Manila Bay. Approaching from the north, Dewey wisely swung to his left so that the sun would he a t the hack of his own gunners and in the eyes of the Spanish. This was, of course, good tactics, and no doubt contributed to Dewey's overwhelming victory. But an earlier clever American propellant innovation was a more important reason. The Spanish started with five ships of the line and 1875 men. I3e\i.eyhad four roughly comparable shipsand l74R men. After the bartle ail of the major Spanish ships as well as all of thr supporting \,essels had been destroyed. The Spanish sufiwrd nlmost 4 0 0 cos~lalties.On the other hand, the Alnrricnns had only seven men slightly wounded and none killed. What made such an overwhelming victory possible? Go hack to Major (later General) Thomas J. Rodman, an American artillery officer during the mid-nineteenth century. Rodman reasoned that if a cannon powder could he formulated which burned with increasing speed as combustion proceeded, the thrust on the projectile could he maintained for a longer time and higher velocities could he obtained. Since the combustion rate of solid propellants is directly proportional to burning surface, this could he achieved if a perforation were hurning outward, thereby increasing the burning surface a s combustion proceeded. This resulted in the familiar seven perforated cannon powder still in use today (Fig. 1). The manufacture of such a relatively complex shape and the reouirement for careful control of the burning surface placed new demands un the physical and mrchanlcnl p n p ertles of l~lackoowder. Therefore. croups at Picatinny Arsenal, Dover, New jersey, and the ~ & a powder l Factory, Indian Head, Maryland, developed "brown powder," a formulation substituting partially pyrolyzed rye straw for the carbon previously used. The use of this somewhat fibrous material created a stronger composition resistant to breakup in the Address correspondence to author c/o Department of Navy, Strategic Systems Project Office. Room 901, Washington, DC 20376.
Actually, the banle of Waterloo was fought in Belgium a few miles south of Brussels.
Figure 1. Seven perforated cannon powder-end view.
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violent turbulence involved in combustion inside the chamber of the cannon. This was the powder used by Commodore Dewey in the last great Naval engagement based upon the use of black powder. America emerged from the war a world power. Propellant chemistry had again influenced the course of history. The Battle of the Bulge On the mornine of December 16.1944. six German Panzer Divisions and three armies drove into the thinnest part of Eisenhower's line. Their objective was the great Port of Antwerp, one hundred miles away, a vital link in the Allied supply line. The weather was foeav with low-lyine clouds. Airplanes could not operate underthe existing weather conditions. Anti-tank guns could not be everywhere. A lightweight and portable infantry weapon was needed; something able to penetrate German armor. Fortunately, such a weapon existed; the bazooka, a small rocket tipped by a cone-shaped charge (Fie. . 2). This weapon could stop the rumbling light tanks and armored carriers of
