The Evolution of World War I Aircraft
Aviators on both sides quickly became essential early in World War I.
The technology they used in the air could make or break them.
World War I (1914 to 1918) laid the foundation for military aviation. Wartime aviation rapidly grew from observation flights in fragile aircraft to the specialized missions still performed today. Explore some of the most pivotal aircraft from World War I and the technologies that supported them in the air.
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Reconnaissance and Observation Aircraft
Finding and watching the enemy were aircrew’s most important wartime duties.
Aviators helped their comrades on the ground through reconnaissance and observation. From balloons, observers informed artillery if their shots were on target. From reconnaissance airplanes, aviators looked for enemy activity behind trench lines. In other combat zones, they scouted over deserts and open seas.
Observation vs. Reconnaissance
In a wartime setting, observation refers to observing things for a sustained period, usually spotting for heavy artillery. For this reason, balloons, which were typically tethered to the ground in this period, were useful in conducting observation. Reconnaissance, on the other hand, refers to actively going out to look for something, like an enemy fleet, or evidence of troops moving to the front lines.
Observation Balloons
Armies had experimented with balloons for observation in previous conflicts. In World War I, this technology found a new role. From balloons, observers informed artillery if their shots were on target. This coordination allowed them to operate with increased accuracy.
Military observers for the U.S. Army Air Service watched and photographed enemy troops from balloon baskets like this one. Flying close to the front lines, they reported details to commanders using telephone lines. Observers also noted changes over time, allowing them to see where troops were being staged for a possible attack, or where the enemy was moving supplies, for example. The balloons were tethered to a winch on the ground and usually floated around 1,500 feet (1,000 feet on windier days).
Each balloon held a vast volume of flammable hydrogen gas that could fill almost half of an Olympic-sized swimming pool. Observers needed to be able to bail-out if they were hit with enemy aircraft fire and set alight. Parachute containers hung outside the balloon basket. Observers wore harnesses attached by lines to the parachute inside the containers. When observers bailed out, the lines pulled the parachute open.
Reconnaissance Planes
At the start of the war airplanes were an emerging technology. They provided militaries with a new way to conduct reconnaissance. Reconnaissance planes became more capable as the war went on. At first, crews verbally reported observations after landing. Newer two-seat planes made room for an observer with a camera. The two-seat configuration quickly became the new standard.
Some planes, like the Dayton-Wright DH-4, were versatile. The DH-4 was used for both reconnaissance and bombing, depending on how it was outfitted. From reconnaissance airplanes, aviators searched for enemy activity behind trench lines. In other combat zones, they scouted over deserts and open seas.
Germany, 1914-1915
Great Britain, 1915–1916
France, 1917–1918
Kodak A-2 Oblique Aerial Camera
Aerial photos became an important part of military planning. But getting those images was not easy. Observers operated cameras, like this Kodak A-2, in the open air and often in freezing temperatures. They also had to fight off enemy planes at a moment’s notice. Radios and defensive machine guns soon made this dangerous duty more effective and survivable.
Getting reconnaissance photos from cameras like this one took time and effort. A U.S. Army Air Service observer held the camera, changing out 4x5-inch glass plates for each shot. Later, other Army personnel processed the plates. Finally, commanders could view the photographs.
Communications and Reconnaissance
Rapidly relaying aerial observations could change the course of battles. Observers used Morse code throughout the war, but it still needed to be translated once it was received. Later in the war, radiotelephones were used to send and receive voice transmissions.
Balloon Busters
Tethered observation balloons were the best way to help artillery troops target the enemy. Observers could see the enemy while staying away from enemy ground fire.
But danger remained. Enemy planes fired incendiary bullets which could ignite the balloons’ hydrogen gas. Balloon busters, as these pilots came to be known, became a standard feature of aerial combat in World War I.
America’s top balloon-busting ace was Medal of Honor recipient Lt. Frank Luke Jr. He shot down 14 balloons before he died in action in 1918.
This souvenir was cut from a German observation balloon, most likely a Drachenballon (“kite” or “dragon” balloon) after it was shot down.
“Many targets are hidden from … [ground] observers. For this reason, the aeroplane and the balloon are indispensable … to the artillery.”
French Observation Manual, 1917
Observation and reconnaissance missions began an aviation arms race. Each side needed to protect their aircraft and attack the enemy’s. This would lead to a new class of armed aircraft: pursuit planes.
Pursuit Planes
Pursuit pilots—later called fighter pilots—flew a new class of high-performing airplanes to hunt enemy aviators.
These light, maneuverable aircraft appeared around nine months into the war. They were also equipped with machine guns. This gave the pilots the means to intercept the enemy. However, making airplanes into effective weapons was one of the greatest design challenges of World War I. Early fighter planes were not well suited for attacking enemy aircraft. Front-mounted propellers got in the way of the best firing position: pointing the airplane at the target and firing forward.
Mounted Guns
Before machine guns were mounted to combat aircraft, observers took hand-held weapons aloft to fire at the enemy. Eventually, planes were redesigned with workarounds to account for the addition of guns, like rear-mounted propellers.
The best solution was the gun synchronizer, which timed bullets to pass between propeller blades. By mid-1916 these innovations led to the formation of the first dedicated fighter squadrons.
Central Powers Aircraft
The Fokker Scourge
In May 1915, Anthony Fokker fitted one of his monoplanes with a forward-firing machine gun and the first operational machine gun synchronizer.
This devastating combination created the Fokker Eindecker. They shot down so many Allied planes in late 1915 that the period was known as the “Fokker Scourge.”
Allied Powers Attempt to Catch Up
Mounting machine guns on dedicated fighter planes was a major design challenge. This became a crisis for the Allies when Germany figured out how to synchronize their guns with the propeller. Through 1916, Allied designers tried many solutions—all of which had problems.
Great Britain, 1916-1917
The 1 1/2 Strutter was the first British aircraft produced with a synchronized machine gun.
It served in the British Royal Flying Corps, Royal Naval Air Service, and French, Belgian, American, Russian, and Japanese air services. Introduced in early 1916, it performed well. By the end of the year, it was outclassed by German two-gun fighters like the Albatros D-series
France, 1916
In 1916, French Nieuport 11s countered Germany’s Fokker Eindeckers equipped with synchronized machine guns.
Without a synchronizer, the Bébé had a Lewis gun mounted to the upper wing to fire above the propeller. The Bébé also had superior performance. This helped end the period of German air dominance known as the “Fokker Scourge.”
Synchronized Machine Guns
Mechanical synchronizer systems allowed guns to fire past propeller arcs without damaging them. The British Vickers and German LMG 08/15 “Spandau” machine guns were the easiest to match with these systems. These Maxim-style machine guns helped pursuit planes develop into effective fighters in the second half of the war.
American manufacturer Marlin Rockwell developed the lightweight Model 1917 and Model 1918 machine guns from the Colt M1895, the first successful gas-operated American machine gun. These synchronized guns replaced the heavier, forward-firing Vickers machine guns on many U.S. aircraft. They armed almost half of the U.S. SPADs and DH-4s.
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The Most Produced Fighter
SPAD XIII Smith IV
The Société Pour L'Aviation et ses Dérivés (SPAD) company built over 8,000 SPAD XIIIs, making it the most produced World War I fighter. Preferred by famous French aces, SPADs also equipped the U.S. Army Air Service.
The SPAD XIII in the Museum's collection, seen here, was flown by 2nd Lt. Arthur Raymond Brooks when he shot down his sixth and final enemy aircraft on October 9, 1918.
A Fierce Little Beast
Sopwith Camel
The battlefield success of the Sopwith Camel made it a lasting symbol of the first air war. Though not fast, the Camel was maneuverable, rugged, easy to maintain, and carried two guns. These qualities made the Camel an outstanding fighter from mid-1917 to mid-1918.
The Camel had handling quirks due to its rotary engine, seen clearly in this photo. It was dangerous for inexperienced pilots to fly in. But skilled Allied Camel pilots shot down more enemy planes than pilots of any other fighter plane—an impressive 1,294 enemy aircraft. In comparison, that’s three times the number of downed Camels.
Central Powers Aircraft
Fokker D.VII
The Fokker D.VII was easy to fly, nimble, and climbed fast. It gave German pilots a performance advantage over their Allied opponents.
Appearing in the war’s final months, the plane was highly feared. D.VIIs shot down 565 Allied planes in August 1918 alone. Even as the tide turned against Germany, the D.VII helped its air force maintain its fearsome reputation. The Allied powers were so concerned that they demanded Germany hand over all D.VIIs in the November 1918 armistice agreement.
The D.VII’s thick, internally braced wing design and steel-tube fuselage pointed the way to future designs. Internal bracing replaced external bracing wires that added drag.
The D.VII’s airfoil (wing cross section) and propeller gave it an unmatched ability to climb from below to surprise Allied pilots. Envious aviators called it “hanging on the prop.”
This metal elevator was used on the Fokker’s tail. It controlled the up and down pitch of the aircraft. On a plane it would be covered in fabric. German aircraft manufacturers pioneered metal aircraft construction. This made it easier to build and more durable.
This is a model of a highly maneuverable three-winged plane. While it climbed well, due to its slow speed and structural problems, only 320 were made.
The triplane was made famous by Germany’s top-scoring pilot, Manfred von Richthofen—the feared Red Baron—even though he mostly scored victories flying other planes.
"Another hot time. 8 [Germans] on me alone. Fokker D.VIIs. Don't know how I got back. 120 bullets in plane, about 5 within 3 or 4 inches from my person. Some maneuvering I did!"
-2nd Lt. Arthur Raymond Brooks
One-on-one aerial combat fit civilians’ ideas of honorable warfare—more so than the bloody, anonymous warfare that took place on the ground. This perception created a culture celebrating pursuit pilots. The most revered were the "aces”—pilots who shot down five or more enemy planes.
Bombers
Aerial bombing was new in World War I. It would go on to becomes a important tactic in future wars.
The Central Powers bombed cities like Warsaw, Paris, Venice, and London. They hoped to force a surrender by terrorizing citizens. The Allies tried to disrupt their opponents’ supply lines. They attacked manufacturing facilities and transportation networks.
For both sides, there weren’t enough planes or bombs in World War I to make a decisive victory.
Airships Terrorize Cities Early in the War
Zeppelins and other German rigid airships flew long-range bombing missions, especially over Britain, terrorizing civilians. Originally used for reconnaissance, they began nighttime bombing raids in 1914, early in the war.
At first airships seemed unstoppable. But then high-flying, night-fighter planes attacked them with incendiary bullets. Many of the highly combustible, hydrogen-filled airships went down in flames.
By 1916, British pilots used new incendiary ammunition against German airships. The burning phosphorous in the ammunition could ignite the hydrogen-filled craft.
The first of the airships brought down over London was the Schütte-Lanz S.L.11. In response, Germany began shifting from airships to less vulnerable, large, multi-engine bomber aircraft.
The First Giant Bomber
To bomb beyond enemy lines, planes had to fly farther and carry much heavier loads: bombs, fuel, and more crew members. Military leaders on both sides invested enormous resources in these large, multi-engine bombers.
In 1914, the Russian Il’ya Muromets was the world’s first quantity-produced, multi-engine aircraft. Future helicopter pioneer Igor I. Sikorsky designed it for the Russo-Baltic Wagon Works (R-BVZ).
The Il’ya Muromets “G” model's four-hour flight time enabled long-range bombing and reconnaissance missions with the Imperial Russian Military Air Fleet’s Squadron of Flying Ships.
The Liberty Plane
Dayton-Wright DH-4
The DH-4 was a versatile light-bomber and reconnaissance aircraft. It served overseas as the primary American-built combat aircraft. Designed by Geoffrey de Havilland for British manufacturer Airco, most were built in 1918 by the American Dayton-Wright company. It was easily modified for different missions. After the war, it supported the development of air mail service.
The DH-4 in the Museum's collection was the first one built in the U.S. It was completed in October 1917, and made over 2,600 flights testing new equipment.
Bombs & Flèchettes
Aerial bombing evolved rapidly in World War I. With the aid of a bombsight, bombardiers could aim at targets while accounting for wind drift and speed over the ground.
Bombs
The Royal Naval Air Service developed some of the first purpose-built aerial bombs. This included the widely used 112 lb (50 kg) RL high-explosive bomb. German airplanes and airships initially used round bombs. Later, they dropped aerodynamic bombs designed for better accuracy.
Flèchettes
Imagine being on the ground when hundreds of deadly flèchettes, or metal darts, fell from the skies. Early in the war, both sides dropped flèchettes from aircraft. But because bombs killed more enemy troops, flèchettes faded from use as the war progressed.
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Ground Attack Planes
In the last years of the war, commanders unleashed airplanes to attack frontline troops.
By 1917, airplanes carried built-in bomb racks and mounted machine guns for repeated ground attacks at low-altitude. This differed from pursuit planes, which were primarily concerned with chasing and shooting down other airplanes and balloons.
The German air force took the idea of ground attack planes further. It deployed ground attack squadrons and planes armored to protect them from troops firing from the ground.
Central Powers Aircraft
Halberstadt CL.IV
Germany developed specific aircraft and squadrons late in the war to attack the front lines, as did Great Britain. German Schlachtstaffeln were ground attack units. They began operations in in 1917 with CL-class light, two-seat biplanes. Later, they flew armored J-class versions. In addition to attacking with bombs and guns, observers dropped grenades and mortar rounds by hand.
The Halberstadt CL.IV was one of the best ground attack aircraft of World War I. It performed well in combat as a low-level attack airplane, relying on its good maneuverability to avoid ground fire.
Naval Aviation
For the first time, aircraft significantly supported naval warfare, forever changing battles at sea.
Naval aircraft operated from both shore bases and ships. U.S. Marine Corps aviation, operating under the Navy, grew rapidly. The most dramatic innovations allowed ship-based airplanes to strike from the sea. The first use of an aircraft carrier occurred late in the war.
By 1915, airplanes were sinking ships and submarines. Aircraft struck their targets with special weapons like air-dropped torpedoes and recoilless guns. Though the number of successful sinkings remained small, ships and submarines now had to contend with these dangers from the sky.
U.S. Marine Corps Aviation Begins
U.S. Marine Corps Aviation came into its own during the war. It began with only five aviators in April 1917. Marine aviators soon made up a patrol squadron in the Azores islands where they helped protect Atlantic sea lanes. Near war’s end, four squadrons in France attacked German targets and supported Allied troops. Pictured is 2nd Lt. Ralph Talbot. He went to France with the first three Marine squadrons, where fought an intense aerial battle with twelve German fighters, earning him the Medal of Honor.
Joseph C. Cline wore this uniform as an ensign while on duty in France. He served with the U.S. Navy Aeronautic Detachment No. 1. Beginning in 1917, it was the first American military force in Europe. Cline flew seaplanes at the first U.S. Navy aerial patrol station in Europe, at Le Croisic, France.
Flying boats—airplanes with boat hulls—let navies scout for enemy ships and submarines near the coast. In June 1918, the U.S. Navy began patrolling the French coast with HS-2Ls. These flying boats also flew the only aerial attack on a German U-boat off the U.S. coast.
Worked Like Two Guns Back-to-Back
Davis Gun
The Davis gun was used to attack surfaced submarines with the largest shell fired by U.S. aircraft. The first recoilless gun, it had a counterweight that cancelled the recoil, or kick, that could damage a fragile airplane. The mounted Lewis machine gun helped aim the Davis.
The Davis gun worked like this: The gunner loaded a round in the center of the barrel and then fires the Lewis gun (small front trigger) to see where shell will land. The gunner then fires the Davis gun (large rear trigger). Simultaneously, an explosive projectile exits the front of the barrel and a recoil round flies out of the rear of the barrel. The recoil from the two rounds in opposite directions cancels each other out, preventing damage to the aircraft.
New Tools for Taking Wing During Wartime
Aircrews gained an edge with new tools to fight, communicate, navigate, and survive the extremes of altitude.
During the war, airplanes flew longer distances, at higher altitudes, and in challenging conditions at night or in cloud cover. Improved aircraft and engine design were not enough to make a difference on the battlefield. Aircrews needed better equipment.
High Altitude Flying
Oxygen equipment allowed aviators to fly safely above 10,000 feet (3,048 meters).
The threat from improved anti-aircraft guns and high-performance fighters forced pilots to climb higher, into thinner air. Without additional oxygen, aircrew could pass out. Prior to these threats, most reconnaissance flights stayed below 10,000 feet (3,048 meters).
Pictured: The pilot of a Fokker D.VII demonstrates a liquid-oxygen breathing system for high-altitude flight.
Britain, 1917-1918
British Lt. Col. George C. Dreyer of the Royal Army Medical Corps developed an automatic system that increased oxygen flow with altitude. Production began in April 1917 at a factory in Paris. The United States later copied and improved this system.
Germany, 1917-1918
Early in the war, Germany switched its aircrew oxygen supply from gas to supercooled liquid. A vaporizer above the oxygen tank converted the liquid to a gas for breathing. This provided greater endurance at high altitude. The German company Ahrendt and Heylandt invented the system.
Communications
Radio-equipped planes improved communications technology and played a vital role in relaying battlefield observations in real time.
Reconnaissance aircraft carried transmitters over battlefields for most of the war. Initially, observers tapped out Morse code messages on “sending keys.” Messages relayed positions of enemy forces. This information helped armies aim their artillery. But Morse code still needed to be translated once it was received.
Rapidly relaying aerial observations could change the course of battles. Using emerging radio technology, aviators instantly transmitted time-sensitive reports with critical information about the enemy. U.S. leadership in radio technology and manufacturing gave the nation an important advantage when it entered the war.
Radiotelephones
Radiotelephones could send and receive voice transmissions. Using these was easier and faster than tapping out Morse code. They didn’t require a separate radio operator in the plane. The U.S. deployed this technology late in the war.
Radiotelephones were unreliable when introduced in 1918. But they laid the foundation for post-war military and civil aviation communications.
Pictured: The hands-free Type 328-W microphone seen in this image attached to a strap worn around the neck. The headphones were part of the helmet.
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Pigeons are Pilots Too
Before radio, homing pigeons were one of the most reliable forms of communications for sailors at sea and troops in trenches. The American use of these feathered aviators really took off during World War I when trench warfare made it dangerous for human runners to deliver messages from the front line. And these birds were not only integral to communications, some even rose to the level of heroism.
All Weather Flying
Bomber crews often bombed at night or under cloud cover to avoid fighters and anti-aircraft fire.
However, low visibility and darkness could easily cause pilots to become disoriented. New gyroscopic indicators helped solve this problem. They gave pilots an artificial horizon to fly by.
Drexler Gyro “Steering Gauge”
German long-range bombers were the first to depend on this technology. Gyroscopic instruments, including this electric one, showed the orientation of the plane in relation to the horizon. This helped pilots maintain level flight.
Engines & Propellers
Engine and propeller improvements enabled wartime aircraft to fly higher, faster, and farther.
As airplanes got larger and heavier, they required greater thrust. To meet this need, warring nations rapidly developed more powerful engines and better propellers.
Engines
"There is a click of the electric ignition switch, the propeller is given a sharp swing over, and the engine starts with a roar."
-Billy Bishop, Canadian ace
Wartime aircraft used four different types of engines. Smaller planes used powerful, lightweight rotaries. These air-cooled engines spun with the propeller. Larger aircraft used either powerful water-cooled inline or “V” engines. Radial engines that combined the advantages of each came into service late in the war.
The Liberty Engine: Made in America
Liberty L-8 (Packard) V-8 Engine
The Liberty engine was one of America’s most important contributions to World War I aviation. It was robust, reliable, and easy to mass produce. Engineers at Packard and Hall-Scott car companies designed the engine in five days. Production of the 12-cylinder (V-12) engine occurred late in the war and ceased in February 1919.
The eight-cylinder (V-8) engine seen in this photo was a prototype. It was the first in a series of Liberty engines. It was the larger V-12 that was mass-produced and which powered the DH-4 Liberty Plane.
Examples of the Allies' Airplane Engines
Hispano-Suiza V-8 engines powered French-built SPAD fighters to speeds over 130 mph (209 km/h). Engineer Marc Birkigt introduced this breakthrough in lightweight engine design. It featured enhanced engine cooling and increased performance.
Hispano-Suizas were built in France and Britain, and by Wright-Martin Aircraft Corp. in the United States.
The Model J engine was most famously used in the Nieuport 17, the French fighter flown by many aces. The Germans copied it by salvaging engines from downed French and British fighters. Many salvaged Le Rhȏnes, and their German-built Oberursel Ur.II copies, powered Fokker Dr.1 Triplanes and other fighters.
BMW (Bayerische Motoren Werk) IIIa Inline 6 Engine
A Central Powers Aircraft Engine Example
In 1916, BMW engineer Max Fritz designed this 180 horsepower engine with low fuel consumption and excellent high-altitude performance. It added an extra 20 horsepower over previous engines, with little increase in weight and size.
The German BMW IIIa powered aircraft such as later models of the famed Fokker D.VII fighter.
Propellers
Propellers convert engine power to the thrust needed for speed, climbing, and maneuvering. Well-made propellers gave combat aircraft an important advantage.
They were constructed of laminated wood, which is lightweight yet strong. Wood is easy to build with and it resists vibrations. But it’s not as durable as metal.
Weapons
World War I aviation presented both a great design challenge and opportunity in regard to weaponry. The beginning of the war saw aviators in pursuit planes shooting handheld rifles and pistols from the cockpit at enemy combatants in other planes. By wars end aircraft were equipped with full synchronized machine guns that could shoot through an aircraft propeller without disruption.
The war also saw the use of bombs dropped from aircraft and balloons. In the case of aircraft, bomber planes were able to fly into enemy territory to disrupt supply lines. However, here weren’t enough planes or bombs in World War I to make a decisive victory on either side.
Learn About Specific Weapons from World War I
Reconnaissance, pursuit, and ground attack planes were equipped with guns but it was the creation of dedicated groups of pursuit planes—fighter squadrons—that has perhaps left the most profound mark on modern warfare.
Naval aircraft struck their targets with special weapons like air-dropped torpedoes and recoilless guns, like the Davis gun. The Davis gun was used to attack surfaced submarines with the largest shell fired by U.S. aircraft.
Aerial bombing evolved rapidly in World War I. With the aid of a bombsight, bombardiers could aim at targets while accounting for wind drift and speed over the ground.
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