The battlefield at Ksar Rhilane in mid-March was littered with broken German tanks and blasted Axis hopes, a shambles wrought by tank-busting planes, the Hawker Hurricane IID and its 40-mm cannon.
Along the scarred and desolate stretches of the front in Russia, hundreds of hulks of Nazi armor stand motionless, grim monuments to the firepower of the Sturmoviks and the fury of their pilots.
At Kasserine, at Faid, through all the passes, fields and valleys of from El Alamein to Tripoli; from the Sea of Azov to Leningrad, hitherto "infallible" tanks lie dead where aircraft cannon have stopped them Sturmoviks, Hurricanes, Airacobras, Lightnings.
Does it mean the end of armored warfare on the ground? Has the airplane, arbiter of modern combat, at last proved its complete mastery and relegated the tank to the military museums reserved for obsolete weapons? The air enthusiast can be expected to reply "Of course," but the questions need to be treated a little more cautiously.
When the Nazis unleashed their lightning war, spearheaded by planes and armored vehicles, demolishing Poland, the Netherlands, Belgium and France in short order and sending the British reeling home from Dunkirk, the world for the most part thought it was witnessing something new in today's modern warfare.
It wasn't. The weapons were new, relatively speaking, both plane and tank. But the principles were as old as warfare firepower, mobility, protection (defensive power). So far as the principle is concerned, it matters very little whether the concentration of firepower is of longbows or howitzers or aerial bombs; whether the mobility is provided by human feet or horses or internal combustion engines; whether the defensive power is a Roman wall, a steel breastplate or a Maginot pillbox.
The application of the principle, however varies radically. This is particularly true today, when it no longer is necessary to sacrifice two of the three invariables to gain the third. The tank embodies all three, but is outshot by the tank destroyer carrying a heavier gun than the tank can mount, but on a tank chassis which gives it equal or greater mobility. The tank destroyer, to gain firepower without the sacrifice of mobility, has relinquished the protection. It has a shield to guard against small arms, but no armor against artillery shells.
The French, having built their Maginot line, sat down to wait behind it, confident the enemy could not crash through. They should have known better but it's odd how seldom the military mind in peacetime remembers the lessons of military history. Not only does every weapon eventually bring forth, of necessity, the defense against it; but defense has never yet been able to stand for long against the attack, the concentration of firepower. It was even a Frenchman, a 17th century military architect named Vauban, who was given to repeating that "Place besieged means place taken." Yet France invited the siege, in the unfortunate assurance that the ways of war had been altered.
So the Germans came dive bombers replacing field guns for a concentration of firepower on a vulnerable spot; tanks rumbling through the gap to roll back the line of infantry with their cannon and machine guns, completely safe from retaliatory small arms fire by virtue of their armor; and finally troops infiltrating in small groups through the demoralized defense lines instead of advancing in massed charges to be mowed down by machine gun fire a la World War I. The Germans had restored mobility to war. They still had their protection, too, only they carried it with them on wheels and tracks or on wings.
The most mobile of all contemporary weapons of war, of course, is the airplane. In the case of the bomber, firepower also is extremely heavy, the destructive force of the heaviest bombs exceeding that of large shells although the "rate of fire" is less because of limited load (a factor offset by mobility and infinitely greater range). Because of the comparative fragility of planes, the power of their guns is not equal to that of field guns, even of identical calibers. And in defensive power the plane obviously is weaker than tank or fixed fortification. The addition of heavy armor would be at the expense of mobility. So, for defense against ground fire of heavy guns, it depends almost entirely on speed and maneuverability. Its defense against other aircraft, of course, is simpler: if speed is approximately equal, so are the weakness of armor and firepower.
Surprise and speed are the chief factors enabling planes to carry out successful attacks against tanks and other ground forces, now that engineers have succeeded at last in arming aircraft with cannon of sufficient size and power to send shells through the upper and side armor of the battlefield monsters.
It's a far cry from the first armed airplane to the cannon-firing Hurricane or Airacobra of today. Since guns were first fitted to an airplane at the Royal Aircraft Factory at Farnborough, England, in 1913, designers have been striving to install maximum firepower on planes. They now are beginning to solve the problems and fit the aircraft with cannon of decidedly respectable size.
The year that saw the first gun fitted to an airplane also saw the first attempt to arm a plane with a big gun. This, too, was a British attempt. A Vickers 1½-pounder gun was installed on a Short pusher floatplane, and the story goes that the first time it was fired, the plane stopped dead and dropped 500 feet.
The designer, Camden Pratt, began a study of the many new problems involved in absorbing the recoil of a heavy weapon. A complete solution has not yet been achieved. That Vickers gun had a half-ton recoil, which is a lot of jolt even for a 1943 combat plane to take.
The experiments continued and, by 1916, the RAF's FB4 had a 1½-pounder semi-automatic gun, while a Davis non-recoil gun was mounted on a Curtiss plane in the United States the same year. The Davis gun avoided the recoil trouble by firing the powder bag out the back as the shell went forward. It was not a completely happy solution.
Throughout all of World War I, only one cannon-armed aircraft actually went into action against enemy ground targets. The gun used was the Coventry Ordnance Works' one-pounder which, because of the manufacturer's initials, became known as the Cow gun. An FB2B plane of RAF Squadron 213 used it with good effect against enemy dispositions behind the line in 1918. But this gun weighed 600 pounds, so its use was decidedly limited in a day when planes were doing all right if they were able to lift that much weight off the ground.
Before the start of the present war, the biggest gun adopted for general use by an RAF squadron was the 37-mm cannon produced by Vickers and installed in the Blackburn Iris and Perth flying boats of RAF Squadron 209.
A gun of the same size is used in the US Army Air Forces two current cannon-armed fighters, the Bell P-39 Airacobra and the Lockheed P-38 Lightning. A ticklish problem of installing such a weapon on a single-engined fighter was solved in the Airacobra. This plane, with its engine behind the pilot turning the propeller with a long extension shaft, permitted installation of the cannon to fire through the propeller hub.
In addition to the very real design problems encountered in mounting large guns on small aircraft, there is the tactical problem of battlefield use of such flying weapons. When flying at 300 mph or better, keeping the target lined up in the sights long enough to score damaging hits is no easy matter. A gun firing 100 rounds a minute could score only five hits in the three seconds it takes to cover a quarter of a mile.
However, hits with a 37-mm aircraft cannon against tanks now in use can be quite effective, and hits with 40-mm guns even more so. "Tanks now in use" is said advisedly, for future designs can be expected to take into account the growing threat of aircraft as anti-tank weapons and provide correspondingly heavier armor on the top and sides.
Ordnance officers, who build the tanks, are inclined to be skeptical of the value of aircraft as anti-tank weapons. If a hit is scored, the tank is likely to be stopped, they agree, but they point out that the attacking plane itself becomes vulnerable to antiaircraft fire. In battle, no commander is going to send his tanks into a fight without antiaircraft gun protection if he can avoid it, and he will also give them fighter cover if he has the planes to do it.
As soon as an airplane starts after a tank, these men point out, it adopts, of necessity, a straight and predictable course, however briefly it may hold it, and as soon as that happens it becomes a target itself. Therefore the successful use of planes against tanks involves the establishment of complete local air superiority, to give the tank-busting aircraft protection against enemy fighters and antiaircraft guns. In other words, it is the old military story not to rely on a single arm but to coordinate the employment of all.
Granting the necessary conditions, however, there is no question of the effectiveness of tank-busting planes. True, their cannon are smaller, being of 37- and 40-mm as against 105- and 155-mm howitzers and three-inch guns of the track-laying tank-destroyers on the ground. Furthermore, the muzzle velocity of aircraft cannon is smaller than that of field guns of equal caliber. Just the same, a hit from one of them on the vulnerable side or upper part of a tank will probably stop the machine. Ground force men say an air attack is a particularly nerve-shattering experience for the men in the tanks, spreading confusion as well as destruction.
Peter Masefield, technical editor of the British magazine The Aeroplane, recently offered an interesting comparison between the hitting power of various sizes of guns and that of a five-ton truck ramming a brick wall. A .303-caliber machine gun bullet hits with a force equal to that of the truck traveling 2½ mph; a half-inch machine bullet with the force equivalent to that of the truck at 6½ mph. In the case of the cannon of various sizes used on planes, the 20-mm equals a truck at 10 mph, the 37-mm equals a truck at 41 mph. The impact of the 40-mm cannon is correspondingly higher.
The 40-mm made its first appearance as aircraft armament in this war on the Russian IL-2, the single-seater, single-engined attack plane famed as the Sturmovik. This is one of four planes developed by the Russians for their own special variety of anti-panzer operations, a combination of low-level attack and dive-bombing which they call "storm flying." There are apparently two versions of the Sturmovik, only one of which is armed with cannon. It is a relatively slow plane, but reports credit it with extremely heavy armor. The Germans have acknowledged pumping huge quantities of bullets into attacking Sturmoviks without bringing them down or even setting an engine afire.
Earlier versions of the Sturmovik had two wing-mounted 32-mm cannon, less powerful but still extremely effective weapons for an attack aircraft. These planes as well as the British Hurricanes are reported using a new type rocket bomb, of which very little has been said. The effectiveness of the Sturmoviks and other Russian anti-tank planes is reflected in the reported destruction of 615 German tanks by Red air force flyers within a period of several weeks. Tass, the official Russian news agency, said the Sturmoviks accounted for "several hundred" of these.
The Douglas A-20 Havoc, known to the British as the Boston III, is a general purpose attack plane, similar to the Britain's fast, heavily armed Bristol Beaufighter, but both of these were employed (with Hurribombers and Kittibombers), against tanks as well as other ground weapons and operations in the brilliant campaign in which Gen Sir Bernard L Montgomery drove Marshall Erwin Rommel's Afrika Korps from El Alamein to the trap of Tunisia.
Air Vice Marshal Sir Arthur Coningham, RAF commander in the Middle East, praised the Boston highly during that campaign. "Those Bostons," said he, "are lethal. Rommel does not like them and we are dosing the Germans heavily with them right around the clock. They do more damage than dive-bombing, and Rommel does not get our Bostons, while we get his Stukas."
Both the Airacobra and the Lightning have been employed against tanks, particularly in Tunisia, although the Lightning performs more effectively at the extremely high altitudes for which it was designed. The Airacobra is an excellent anti-tank plane and has proved itself not only in Tunisia but also on the Russian front, where the Red Army flyers like it heartily.
Most highly specialized tank-busting aircraft now in use by the Allies, however, is Britain's new Hawker Hurricane IID, which got its first news attention at Ksar Rhilane, below the Mareth line, on March 12. There Rommel had sent out 30 tanks in a savage counter-attack designed to stave off the impending successful assault on the line by the 8th Army.
But the Hurricanes, as heavily armed and much faster than the Sturmoviks, roared over the German armor. Protected by fighters, sharing the fight with other low-flying attack planes, they ripped at the enemy throughout the day and destroyed all but nine of his force of tanks. In the first sweep, they knocked out eight vehicles, and in the second, two. Doubling the bid, they rushed at the tanks again, and got 11. Three sweeps and 21 out of 30 tanks were stopped. Just to cap it, the attack planes knocked out seven guns, and in the day's operations sent the enemy troops into a precipitate withdrawal from Ksar Rhilane.
The new Hurricane IID is considered one of the best tank-busters in the air today. Complete data had not been disclosed at this writing in fact, little is known beyond the fact that it does mount two 40-mm cannon (too long to be mounted inside) and therefore streamlined into bolts fixed to the underside of the wing. [The RAF subsequently has announced that each cannon weighs 350 pounds and each shell 2½ pounds.]
Presumably, even larger guns will make their appearance on planes before this war is over. Presumably also, at least some additional protection will be built into newer model tanks. It has always been so with the weapons of war throw a new weapon at the enemy and his necessity will provide the defense. Has the plane doomed the tank to oblivion? Certainly the decisive importance of the tank has declined considerably since the start of the war. The plane, in new tactical uses developed by the Allies, has had its brilliant share in that decline. But to answer the question, it might be more reasonable to say that the tank-busting plane and the tank-destroying self-propelled artillery together have deprived the tank of its mastery.
Again, firepower has overcome defense.
This article was originally published in the July, 1943, issue of Flying including Industrial Aviation magazine, vol 33, no 1, pp 21-23, 128, 130.
The original article includes 6 photos: 2 of P-39s, a P-38, a Hurricane IID, and two of burnt-out Panzers.
Photos credited to Rudy Arnold, British Combine, Acme, Bell; 2 photos not credited.