I'm Jake O'Neal, creator of Animagraffs. And this is how a World War I era biplane works.
I've chosen to emulate a specific make and model whose name I'll include in the
description due to its uniquely beautiful and familiar sounding pronunciation.
This plane was manufactured around 1918,
which is only about 15 years after the first powered flights.
It features a lightweight welded steel tube frame, which was new aviation technology in its time.
Piano wire with tensioners stretches between frame sections,
from corner to corner at various critical angles.
There are wooden pieces to make special brackets which hold moving parts,
and for convenient fabric attach points.
There's an arched plywood panel extending from the tail to just behind the cockpit.
The wings are made almost entirely of wood, including spruce and birch plywood.
Bands of woven material are laced between and also
attached to the top and bottom of each rib to keep them from twisting.
The horizontal spars are hollow. They're made from laminated layers of plywood,
with vent holes to prevent bursting from low air pressure at high altitude.
The leading edge of the wing is formed with thin plywood sheathing shaped around the curved ribs,
for strength against torsion, or lateral twisting.
Left and right ailerons, which are part of the flight control system, are made of steel tubing.
These were some of the earliest examples of a cantilever wing design,
where strength comes from the internal structure,
as opposed to other common designs of the time where the necessary rigidity came
from drag-inducing external bracing and dense webs of supporting wires.
For the cantilever wing, no external wires are necessary,
and only a few bracing pieces are visible at the exterior between the topwing and the underwing.
The front of the frame has more intricate and specially shaped metalwork to support
the engine, wings, and landing gear attach points.
Stretched over this skeleton frame, pure linen fabric forms much of the exterior shape.
The wings, rear fuselage, and tail parts are all clad in linen,
which was synthetically dyed or custom painted by pilots
with special compounds for increased durability against sunlight exposure.
Stitching at the underside of the fuselage allows access to internal wire bracing,
which would often break from stress during hard maneuvering, for example, in dog fights.
The wings feature a so-called "lozenge camouflage", named for its unique colored
shapes, with darker hues covering top surfaces, and lighter colors underneath.
The outer appearance and paint schemes for these planes often varied dramatically between pilots.
The front of the fuselage or body of the plane is wrapped in aluminum paneling. The running engine,
guns, and associated components mounted here have increased risks associated with heat and fire.
There are louvers to allow heat to escape.
Now, let's focus on specific parts of the airplane, starting with the engine.
These planes featured a six cylinder engine of either Mercedes or BMW make,
with the base power output rating at 180 hp, and a max traveling speed of 118 mph.
The valve springs and associated components are visible at the top end.
There's an exhaust manifold at one side. Air is drawn in
through a separate compartment in the crankcase to benefit from engine heat, and combat icing.
The geared camshaft, which extends up from the bottom end of the engine, is also a connection
point for various components which we'll see later, including a synchronizing gear system so
onboard guns could fire between propeller blades. The radiator at the front is supplied from any
of various automobile makers, then modified to fit the plane.
There's a pilot-controlled shutter at the back of the radiator to block
airflow and thus regulate cooling effect. At the bottom-front side of the engine,
there's bracketry which directly connects the propeller to the engine's crankshaft.
Bolts were regularly checked since the wood propeller expands and contracts with
cold temperatures at high altitudes. The max altitude for this plane is 6,000 m (20,000 ft).
The propeller is made of birch or walnut wood, which is glued together in layers and formed
into its final shape through various carpentry methods, then sealed with a protective finish.
It's 278 cm or about 9.1 feet from tip to tip.
Moving aft or rearward, we see the painted brass fuel tank, with a total capacity of 93 liters
(24.6 gal) between its main and reserve tanks, for about an hour and a half of flight time.
A separate compartment in this tank also holds 25 liters (6.6 gal) of oil. There's
a metal firewall at the front to protect rearward components, and the pilot, from engine emissions.
Heading further aft, we enter the cockpit.
From the left side looking forward, also called the "port" side, we see the throttle lever,
and a fuel mixture lever to control the ratio of fuel to air in the engine.
In front of that, a small spark advance lever alters spark timing,
especially when starting the engine. At the leftmost side of the dashboard,
there's the magneto switch, which is essentially the "on/off" switch for the plane.
The handle is removable to prevent unauthorized starting.
Each cylinder in the engine has two spark plugs. The switch can toggle electrical connectivity to
the first bank of spark plugs, the second bank, or both, which is the normal running position.
The "Anlass" label next to the first setting essentially translates to "start".
This setting supports the engine starting process. These planes and many others of the era don't
have electric starters. To start the plane, a decompression handle on the engine is engaged
so the valves don't close all the way, making the engine easier to turn by hand.
A person on the ground rotates the propeller a few times to prime the engine,
sucking fuel into the cylinders. Back in the cockpit, the pilot
cranks the starting magneto, which acts like a little electric generator.
With the magneto switch in the first position, a so-called "shower of sparks" is generated, sending
sparks to multiple cylinders. The resulting detonations cause the engine to begin to turn,
and the normal running process fires to life. When the engine is fully operational,
the M1 position functions as normal, delivering a timed spark to individual plugs.
This starting sequence has the benefit of added safety in that the ground operator is only
priming the engine but doesn't need to contact the propeller to directly start the engine,
as with other models of the era. Returning back to the dashboard,
there's a switch to select a fuel source, from the main tank, or the auxiliary tank.
There are fuel pressure gauges for each tank nearby.
The main fuel capacity gauge is mounted further forward,
near the fuel tank, under its own little fairing.
There's a large tachometer gauge front and center, with the highlighted redline at 1,400 rpm.
Airspeed is measured by the anemometer,
which is mounted far outside the cockpit on a wing strut to avoid propeller wind.
At the right or starboard side of the dashboard,
there's a small grease pump to manually lubricate the engine's water pump.
Beneath that, there are switches to control air pressure.
The left switch directs air pressure to main or reserve fuel tanks,
and the right switch can select between a motor-driven pump,
or the nearby manual hand pump, which was used to pressurize the fuel system for starting.
Below that there's a pull wire for the previously shown radiator shutter.
Further down on the right side near the seat,
there's a compass on a floating mount to maintain level,
with an adjustable pointer as a visual aid for staying on course.
At the back of the cockpit, there's the seat, which is a curved aluminum sheet
which forms the back and sides, with a basic plywood seat bottom.
Our model has leather upholstery for the seat back, and a simple seat cushion.
The seat frame is adjustable up and down, and secured with wire to keep from slipping in flight.
Turning forward again, we see the central stick and foot controls,
which are part of the flight control system which we'll examine in a minute.
There are textured metal pads to keep pilots' boots from wearing through the thin plywood floor.
The stick at the center has a shaped wooden handle for maximum grip.
The dual wooden handles at the left are redundant throttle controls.
Pilots often needed two hands on the stick as there are relatively few modern
flight control aids in the plane's design. As such, the throttle control has a screw to
adjust friction, and help prevent unintended throttle changes when gripping the stick.
At the center there are two trigger levers positioned for easy access
for the pilot's pointer and middle fingers. These correspond to two
respective onboard machine guns, which we'll also examine in a bit.
Now, let's have a look at the flight control system.
Wires are connected to the foot bar and the stick. Tracing any of these wires will eventually lead
us to a direct connection to a movable control surface.
Moving the stick front to back
rotates the elevator at the tail,
controlling the plane's pitch angle.
The stick itself is attached to a bar which rotates side to side
to control the ailerons at each wingtip,
which affects the plane's roll angle.
The small area in front of the hinge point balances the aileron to reduce pilot workload.
The wires are cleverly routed in a mirrored loop such that rotating the
bar yields equally opposite rotation from side to side.
Wires stretch from d-rings at either side of the foot bar
to the rudder at the tail,
which controls yaw, or the vertical angle of the plane from the pilot's perspective.
This direct connection means pilots must maintain contact with flight controls at all times,
with the stick and foot bar requiring constant input at every moment during operation.
Landing Gear
The landing gear has sturdy struts which extend from the frame to the axle housing.
Wrapped around this housing, there are additional ribs and structure for a mini airfoil
to reduce drag around the axle tube and provide a bit of additional lift.
The axle itself has a simple suspension system at each side.
There's a rubber cord which passes over the axle and winds around posts at the front and back.
The wheels are a fairly standard hub and spoke design,
with drag-reducing metal covers
and 100 mm (4 in.) wide rubber air-filled tires suitable for operating in rough fields or mud.
At the tail, there's a simple springed wooden tail skid with some allowed side movement for turning.
Guns
There are two machine guns mounted just in front of the cockpit.
The shoulder stocks have been removed and padding added for pilot safety.
There's a rounds remaining counter mounted at the back of each gun.
Ammunition is supplied by 500-round belts that rest in a metal bin underneath.
There's a metal tube to guide empty ammunition belts into a forward bin for later reuse.
Bullet casings eject out the bottom; a metal chute guides them away from the airplane.
There are also metal blast shields along the firing path for protection.
The limitations of world war one artillery made it most convenient to mount these guns
on the sturdiest part of the frame, and in a place with easy pilot access.
As such, they are aligned to fire through the path of the propeller.
This is accomplished with a synchronizing gear setup that links gun triggers to the engine
for a perfectly timed firing sequence between spinning propeller blades.
Through connection to the engine's camshaft,
a gear turns two separate gears, one for each gun respectively.
Let's focus on a single side. Trigger cables are routed
from the previously shown control stick triggers and connect to the system here.
Pulling the trigger actuates a lever which slides a double-ramped disc forward.
The ramps ensure that the bar doesn't actually
rotate the disc until it reaches the proper alignment and therefore the proper timing.
As the cable spins, a pair of angled gears at the other end rotate a pinched oval-shaped piece
which pulses the gun's trigger lever in perfect sequence,
for as long as the stick mounted trigger is engaged.
The spinning disc disengages instantly when the stick trigger is released.
Pilot The open air
cockpits of this time period meant pilots often needed to withstand very cold temperatures.
Our pilot wears an early leather crash helmet design,
Goggles have glass lenses and metal rims with textile and leather padding.
Pilots often wore leather face masks to fight frostbite and also, apparently, to look like
something out of a modern horror film. Harness straps extend around the pilot
from the seat bottom, and are secured together with a small stud and cotter pin.
The pilot wears a leather flight suit among other heavy insulating layers,
though flying gear of the time shows much variation here.
Thick leather gloves and boots complete the ensemble.
These early flying machines are exceptionally beautiful in their simplicity. It's fascinating
to see how the basic components for flight have carried on into modern aviation design.