Weaponary Leonardos Steam Cannon Merged

WERPOilRY
Leonardo da Vinci'S steam cannon foreshadowed
the steam engines of the lndustrial Revolution.
By Nick D'Alto
"WHEN THE WATER HITS the heated
part of the machine," the barely legible handwriting informs us, "it will be
turned into so much steam that it will
seem fantastic. This weapon has driven
a cannonball weighing one talent [60
pounds] a distance of over 6 stadia
labout two-thirds of a mile]." Beneath
these scribblings in a notebook of
Leonardo da Vinci's there is a sketch,
apparently rendered in haste, of the
Architronito, a cannon operated by the
expansive power of steam. The genesis
of this unusual weapon and the social
and political climate that fostered it
reveal much about the changing
nature of warfare during the Italian
Renaissance.
Although best remembered today as
the painter of such masterpieces as the
Morn Lba and Thc last Supper, the multitalented Florentine Leonardo da Vinci
(1452-1519) actually spent most of his
career as a consulting military engineer.
It
was a profession in high demand
among the warring city-states of late
lSth-century Italy. During those unsettled
times, the Kingdom of Naples, the Republic of Siena, the Dukedom of Milan,
and Florence under the Medicis found
themselves in intermittent mutual conflict. Papal armies threatened as well,
while French, German and Spanish soldiers invaded and fought each other on
Italian soil.
This was the volatile world of Niccold
Machiavelli, who as
Florentine ministerof
war counseled the
princes of Italy and
between the ancient and the new. His
alliances and cruel
politics of the age.
ballista and catapult reach back to
Roman archetypes,laid down inthe mili-
Paradoxically, a tyrant
of that day might conquer a crty by force of
arms onlyto rule as its
leading patron of arts
tary treatises of Pliny and Vitruvius. The
most interesting weapons in the notebooks, howeve4 incorporate futuristic fea-
catapult combined.
By that same irony,
the skills for casting
bronze statuary for a
public square served
equally well to forge
cannons. Da
battle
s
3 Vinci, the intellectu-
18 MILTTARY HISTORY MARCH/APRIL 2()O5
Leonardo's drawings testify that late
navigating the swirling
Pax Romana with
Mona .Lisa and the
Archimedes, around 1500.
Leonardo's now-famous notebooks.
in the delicate art of
and letters-a sort of
A page from Leonardo da Vinci's notebook reveals detailed notes
and diagrams for an Architronin, a deadly steam cannon named for
strategy. The change is evidenced in
Sth-century battle technolory still occupied a kind of transitional state, halfway
otherEuropean states
E
and the weaponeer and give rise to the
period's leading technology specialist, the
consulting military engineer. Though privately he decried war as "a bestial madness," da Vinci would play a supporting
role in combat formost of his career.
Men such as Leonardo were indispensable to Renaissance-era rulers. Like the
quantum leaps brought on by movable
type and transoceanic exploration, 15thcenturywarfare was beginningto shed its
medieval trappings for a more dynamic
future. As the old dependence on ballistic
siege engines, such as the trebuchet and
catapult, gave way to the increasing mobility and superior destructive power of
cannons and mortars, the new technolory
demanded new strategies in siegecraft,
defense, battlefield tactics and general
ullv versatile "Renaissance man" of lore,
would eventually meld
the talents of the artist
1
tures. Astonishingly, Leonardo's cannons
were breechloading, apparently the first
of their kind. His projectiles were aerody-
namically streamlined to extend their
range, and guided to their target by a sophisticated empennage of crossed tail fins.
His incendiary bombs were designed to explode with lethal (and essentiallymodern)
shrapnel on impact. His small arms were
fired by the first flintlocks ever devised. All
those innovations were conceived centuries before they became commonplace.
Equally remarkable, for the fust time
Leonardo's stunning use of perspective
created lifelike renderings of complex
weapon systems, sufficiently accurate to
conceptualize the devices and predict
their performance entirely on paper, a
kind of l5th-century computer-aided
design. We meet soldiers manning a great
crossbow maneuvered on six canted
wheels. Its 135-foot-span bow is built up
from laminated sections, flexed by an
arm-thick bowstring drawn to the firing
detent by capstans and worm gears.
In another plan, the weight of 20 soldiers works an immense treadwheel that
revolves stockbows automatically before
a sharpshooter seated within. Leonardo
calculated that 30,000 pounds of thrust
wouldpropel each arrowto its target. And
a leviathan dredging machine evinces an
audacious batde plan, diverting the Arno
River in a diabolical attempt to rob besieged Pisa of its supply line to the sea'
Leonardo's foresight is nowhere more
evident than in his revision of cannon
technolory. For the previous cenhrry, most
cannons were cast from cuprum (bronze),
but with the primitive boring methods
used in the mid-l5th century, the hammered stone projectiles typically fired by
these pieces fitted only loosd down the
bore, greatly diminishing their range and
power. Worknen often built up larger field
pieces from wrought iron bars, welded
edgewise and then stayed, barrel-like, by
iron hoops. Whether the resulting bore
would even approach true, given so many
separate parts, seems far from certain.
Leonardo's improvements to cannon
design were many: breectrloading, often
through a screw-threaded breechblock;
improved casting techniques to achieve a
tighter-fitting sho! water jackets' an astonishingly modern cooling technique to
allow guns to be fired more frequently;
and even the first cartridge, with cast iron
ball, powder charge and an ignition
primer packaged in a single shell for rapid
loading. DaVinci also designed anamazing variety of light cannons, sometimes
employrng multiple barrels in revolving
rapid-firing designs that admirably prel
saged the cart-mounted Gatling guns of
the l9th-century U.S. ArmY.
In all such plans, Leonardo exhibits the
Renaissance spirit of experiment, often
annotating the results of his experiments
or the design of test jigs to prove a construction principle. For example, standard
artillery texts in leonardos day (and even
to the 17th century) offered inaccurate il-
lustrations of projectile flight, depicting
an initial diagonal rise, then turning
sharply to complete a nearly vertical fall.
By observing a propelled perforated
leather bag spouting jets of water,
Leonardo revealed the tme parabolic tra-
depicted in its firing position via a cutaway section of the barrel. Clearly, the
scene is preparatory to firing, as smoke
jectory of missiles, as well as the relations
of force, angle and carry-in effect deducing the first accurate telemetry.
Equally impressive are Leonardo's machine tools for fashioning his improved
cannons, which were often highly automated and designed to execute multiple
manufacturing steps through intricate
airangements of dependent gears and
linkages. In one scheme, a turbine similar
to a Pelton water wheel energizes a series
of helicoidal gears and meshing worrns
to draw bronze blanks into
and flames are shourn already rising
through the brazier lid.
Beneath Leonardo's terse explanation
of the device is the final drawing, rendered only schematically, showing the
completed weapon. Da Vinci evidently
envisioned the Architronito as a field
piece; it is mounted on a traction-wheel
gun carriage, with a skid leg to stand
against recoil. An additional support extends from the muzzle end as a kind of
tapering
metal staves, which become edge-welded
foundation block, apparently to stabilize
the muzde during firing.
Da Vinci's notations of shot and range,
as well as his description of the terrific
din during firing, suggest that a prototype
of his steam cannon was actually built
and tested in his day-a testament to the
zeal with which new forms of weaponry
were actively pursued during this era of
both desperation and growth. Howeve[
to create an elegantly strong cannon
barrel of true bore. His famous rendering
of a cannon foundry courtyard depicts
the leviathan scale of his new weapoffy,
including a platoon of men hoisting a
cannon barrel the diameter of a man to
its gun carriage on a stiffJegged derrick.
The finishing touch was the master's
new design for fortifications: not the hightowered fairytale castles designed to with-
whether operation of the Architronito
ever extended to actual field use by the
armies of Sforza, Borgiaoranotherof the
military leaders da Vinci senred during
his long careeris a chapterunfortunately
stand catapults, but a low rounded
citadel evolved specifically for the new
age of gunpowder. A quick sketch depicts
one of Leonardo's bombards positioned
at the parapet wall, among the earliest
known proposals for mounting cannons
lost to history.
The source of Leonardo's inspiration
for the device remains somewhat hazy'
He certainly would have winressed the furious boiling of water that occurred while
quenching gun banels during boring. But
*hil" it is obuious thatgunbarrelsbecome
hot during formation and during fuing,
the willful heating as a means to expand
a working fluid (steam) as the firing agent
represents genuine innovation; of all the
Renaissance engineers, no one except
Leonardo seems to have considered it.
Tiaken in a larger sense, this l5th-centuryweapon represents more than simply
a new way to fire a gun. In hindsight, we
within the castle itself.
Leonardo applied much of that same
insight in the development of his steam
cannon. Probably sketched about 1500,
da Vinci's drawings indicate a narrow
cast-bronze gun barrel. The bore is very
long, probably to improve firing accuracy
in the days before rifling. Modern analysis places it at about 7.25 inches in diameter. In place of a breech section, a coal-
fired brazier surrounds that end of the
barrel to heat the bronze itself to a very
high temperature. A set of injectors then
sprays a small quantity of water into the
barrel, just behind the shell. According to
da Vinci's notes, the resulting expansion
of superheated steam would propel the
shot with terrific force' The weapon's
name, Architronito (apparently a nod to
Archimedes), seems to have been Leo-
can see that Leonardo's piston, cylinder
and injector arrangement, albeit in a
'
'
more destructive mode, foreshadowed
the modern steam engine, a device that
wouldenergizethelndustrialRevolution
nardo's invention as well.
centuries later,
Da Vinci developed the weaPon in
three drawings on a single notebook
sheet, with two additional constmction
details provided. The first drawing tilts
Vinci's rapid sketch, Union forces during
the American Civil War employed steamfired ligtrt carurons of remarkably similar
the device toward the viewer to reveal the
workings of the brazier door. The center
illustration delineates the operation of a
square-section hydraulic screw press that
drives the pressurized water through the
injectors. A detail of the press plunger is
provided. Additionally, the cannonbali is
More than three centuries after da
in successful assaults
against Confederate batteries. More recently, the Holman Projectors of World
War tr also tapped the expansive power
configuration
of steam to fire hand grenades at aircraft,
the surprising offspring of this Renaissancegenius. illH