Lords of the Sky: Fighter Pilots and Air Combat, From the Red Baron to the F-16 (8 page)

German training was predictably much more structured. Prewar training was at bases such as Halberstadt and accomplished in slow, steady aircraft such as a Bristol-Taube. Underpowered and generally forgiving, it was a fairly good trainer. It also had dual controls, and a student typically took three to four hours of instruction prior to his solo. The entire course lasted about two months and was very, very basic. But again, in 1914, aircraft were used for reconnaissance and artillery spotting, so no one really gave much thought to flying that wasn’t straight, level, non-maneuvering, and during the day—yet.

At the beginning of the war the French Air Service had been the most progressive in both aircraft design and organizational thinking. It was the first to group aircraft together by specialized types, and by March 1915 there were four such groups: Bombing, Infantry and Artillery Cooperation, Reconnaissance, and Fighting.

However, the French training system was unique in that no dual instruction was used for prospective fighter pilots. Their philosophy was that a man best learned to fly through a self-paced increase in his comfort level, based on gradual exposure. In the
rouler
phase, a student was placed, by himself, in a scaled-down Blériot with an underpowered 25-horsepower engine and half wings. This contraption couldn’t fly, but it could, theoretically, familiarize a student with controlling a machine.
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If the machine was run at full throttle, the tail would actually lift and the student could “fly” across the field on the rollers—the wheels.

Then came the
décoller
class, where a student, again with no real instruction, could get a few feet off the ground.
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This was usually accomplished using a field with a hump in it, followed by a slight depression, so the plane could get airborne. The
pique
class still involved flying in a straight line, with no maneuvering. Then finally came several
tour de piste
flights. In this phase, a student was permitted to fly around the field about 600 feet up. The future pilot next did a “high-altitude” flight, then spirals (spins), and after that was ready for his
brevet
tests if he had the total hours required. This number varied throughout the war, but by 1917 a student needed fourteen hours before being allowed to take his tests. Then he began a series of
petits voyages
—cross-country adventures to unfamiliar aerodromes. Upon completing this he was now
un aviateur,
a pilot. This system took a great deal of time and produced wildly inconsistent results.

Not surprisingly, as combat losses increased, pilots were needed much faster, and so was some type of minimum standard. By the end of the war, the French had adopted the British method, and the Americans did the same.

AFTER LOSING AIR
superiority to the Germans over the Somme, the Allies were well aware of what they had to do in order to deal with the Fokker Eindecker and its biplane cousins. Increased understanding of aerodynamics and the construction process resulted in several significant changes. Biplanes, with their increased lift and wing loading, were now the standard design. Wings became thicker as the principle of lift was better understood, and this allowed greater strength for violent maneuvering. Monocoque fuselage construction also became commonplace: the external skin supported loads and was no longer merely a covering, thus streamlining the aircraft and making it much, much stronger. A stronger airframe permitted more powerful engines and heavier armament, and it could also now withstand the stress of dogfighting. The true fighter aircraft was born.

Engine design also drastically improved. Prior to the war, aircraft and automobile engines had shared the stage, but this changed rapidly. Cars only ran for limited periods, didn’t need much power, and had to be inexpensive to manufacture. Aircraft engines had to run continuously with great power, and they had to withstand drastic atmospheric changes, primitive maintenance conditions, abuse from pilots, and battle damage. They had to be powerful, tough, and reliable, and as governments were the customer, cost ceased to be a limiting factor.

There were two basic types of piston-driven combustion engines for military aircraft at the start of the Great War. In a
rotary
configuration, the entire engine spins around the crankshaft. This has several advantages. First, it is a very smooth, practically vibration-free engine, so this means less wear and a more stable gun platform. Though a rotary produces significant torque, this can be overcome by the rudder.
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Rotary motors are easy to air-cool, so no extra fluid is needed and the system is much lighter. Less weight usually results in excess lift, which can be exchanged for better performance and maneuvering.

But since it’s spinning around in the airstream, a rotary engine produces a great deal of drag. Hence 200 horsepower was about the maximum power you could give a rotary engine before it became impractical. It was also a fuel guzzler, consuming 20 to 30 percent more fuel than stationary motors, thus effectively negating the weight saved from air cooling as it required more gas. Or you settled for an aircraft that carried less fuel with a correspondingly shorter flying time.

Stationary
engines, which remain fixed while the crankshaft spins, became the norm after 1916. One way to produce more power was to increase the displacement in an engine. This is basically the volume of air in each cylinder that is moved, or displaced, by the piston. More air displaced means greater pressure inside the combustion chamber, which generates more horsepower. You can create displacement by making bigger pistons or by adding more of them. Larger pistons mean more frontal area, greater weight, problems fitting them into an airframe—or all of these. So designers began adding cylinders, all the way up to the Liberty V-12 in 1918, as a way to increase displacement.

Also key in producing engine power is the compression ratio. Think of a big can (the cylinder) with a smaller can inside (the piston). As the piston moves up and down it pushes, or compresses, the air in the cylinder. This “packed” air, when mixed with fuel and ignited, generates the energy to operate the engine. Greater compression results in a more powerful explosion, which can mean more horsepower. In 1914 the typical ratio was about 4:1, and this increased to 6:1 by the end of war through improvements in design and fuels.

The arrangement of the cylinders was also important and directly affected performance.
Inline
engines placed them down both sides of the crankshaft, while a
radial
configuration made a star shape. “V” motors angled the cylinders up and away from the shaft. Lubrication was a challenge, since castor oil was the only available fluid that could be mixed with fuel and remain effective at high engine operating temperatures. A vegetable oil derived from the castor bean, it was ideal for engines that were taken apart and rebuilt regularly, like aircraft motors. During the war a rotary engine needed a complete overhaul for each twenty-five flying hours, while inlines were rebuilt at around the three-hundred-hour point.
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Improving fuel also resulted in power gains. Aircraft engines of 1914 were operating on low-octane fuels (40–70 octane) of dubious quality. Fuel with higher ratings can be compressed more before detonating, thus producing more power, and by the end of the war aviation fuel was up to about 80 octane. As a result of shortages caused by the naval blockade, Germany led the world in developing chemical additives and synthetic replacements for necessities such as oil and rubber. This chemical research carried over into fuels, but there was still never enough to meet demand.

Engines and airframes could be improved and refined, but literally at the end of everything lay the propeller. If it was primitive or inefficient, then any improvements in engine power and performance would matter very little. Props that attached directly to the crankshaft were fine in early aircraft, but as engine speed increased above 1,500 rpm the propeller simply couldn’t spin fast enough to keep up. So a reduction mechanism was added whereby a series of gears transmitted the motor’s energy without the speed. This gave a propeller power, but at a manageable number of revolutions per minute.

However, the best-designed fighter aircraft in the world is just for show without weaponry, and aerial gunnery was fast evolving into an art. The guns themselves were good by this time, though ammunition was often a problem. Badly fitted rounds in canvas belts could cause a jam or even explode. The metallic belt-and-link system had been added, which was a great improvement, but really good pilots still armed their own planes whenever possible.

Tracer shells had a chemical (usually phosphorus or magnesium) in a hollow base that would ignite and leave a visible trail, which allowed the shooter to correct his aim instantly. Unfortunately, the weight of the tracer shells was different from that of ordinary ball bullets, so the trajectory was different. Also, the chemical sometimes burned out early. Both factors could make aiming corrections problematic, but tracer shells were better than nothing at all.

Gunsights were similarly being continuously refined. Unless you happened to be directly behind or in front of a target, there were
deflection
angles involved in getting a bullet to hit. Compensating for these angles required “leading the target” as it moves across your line of sight. Think of playing dodgeball and aiming your throw
ahead
of where the target is frantically running.

Visualize a big half circle, a 180-degree arc, extending out 200 yards in front of your cockpit. Any target within this arc is something that you can turn, point, and shoot at fairly easily. One degree of this arc (referred to as a
mil
) equals 1 foot at 1,000 feet.
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If you then extend your 1-degree cone out to 2,000 feet, the same mil is 2 feet wide.

If you have a known reference, such as the size of your gunsight, then you can estimate the range to your enemy by how much of him fills up the sight. For instance, the Albatros D-I had a 28-foot wingspan. Understanding mils now, we know that at 1,000 feet an aircraft with a 28-foot span would fill a 28-mil aiming reticule. Of course, 1,000 feet is much too far to shoot with your Vickers gun, so we double the aiming reticle to 56 mils, and the target’s wingspan would fill it at 500 feet. (See Appendix A, “Anatomy of a Dogfight.”)

One of the first aerial sights was called a
frame
or
gate sight
. This was a little metal rectangle just like a picture frame, and the idea was to put the target within the frame and shoot away. Adapted from a naval gun-laying system, it worked well enough against non-maneuvering aircraft such as bombers and reconnaissance planes. The early Fokkers flown by Boelcke and Immelmann had gate sights because there was no alternative. But it only really accounted for deflection if the target was moving horizontally across your line of sight, and once aerial fighting evolved to aggressive, three-dimensional maneuvering, another solution was needed.

A
ring sight
was constructed of concentric metal circles and was mounted on the back of the gun. Up near the muzzle was a vertical post with a small red painted bead on the tip. If you lined up the tip of the post within the inner circle of the ring, then the bullets would go where you aimed them at zero degrees of deflection. However, by using a ring instead of a frame, you could now also judge lead angles for deflection shots no matter how your target was maneuvering. Guns were typically bore-sighted for 200 yards and the rings were sized to assume an enemy traveling at 100 mph was crossing perpendicular to you at a full 90-degree deflection angle. This meant a bullet time of flight of two and a half seconds against an enemy who would travel about 38 feet during that time. Another part of the mental gymnastics you had to do while flying and fighting was to compensate for the bullet drop (against gravity), since none of the sights did. However, it was known that a Mark VII shell fell 14.4 inches over 200 yards, so the pilot just had to wing it and aim a bit high. It took a lot of practice.

Single-seat pilots had to do this alone and rarely had the time that gunners and observers enjoyed in multiseat aircraft. They needed some way to accurately and immediately point and fire without aligning rings and beads. In 1915 an optical sight was proposed by the Aldis brothers of Birmingham, England. Like a modern rifle scope, the lenses provided several key advantages. It showed a prealigned aiming point that appeared over the target image. Unlike iron sights, the viewer’s eye distance from the sight makes no difference, since the lenses are collimated, or focused on infinity; as a result, the pilot doesn’t have to hunch forward to shoot.

The prototype had a 3X magnification, which would be fine for a stationary rifleman but proved extremely disorienting to a pilot moving at 100 mph, so the magnification feature was discontinued. The outer ring was sized to provide a full deflection shot against a 100-mph target at a range of 200 yards. All four lenses were hermetically sealed, and the tube was filled with an inert gas to prevent fogging. Because it was mounted on the cowling, the sight could be obscured by leaking engine oil, so an anti-fouling flap was installed that the pilot could close or open as needed. Later production sights protruded through a hole cut in the windscreen.

British fighters began flying with operational Aldis sights by mid-1916, and they became standard equipment for the last two years of the war. Both the French and the Germans copied the Aldis sight but didn’t get them fielded until 1918.
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WERNER VOSS OF
Jasta 2 saw the ungainly, slow-moving FE-2 reconnaissance plane and immediately pounced. It wasn’t much of a fight.
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