The Physics of Javelin
Throwing
How to Make the Javelin Fly Far
101
• Maximize release velocity
• Maximize the aerodynamic efficiencies of the
javelin
• Maximize the height of release without
compromising the first two items
Qualities of the Javelin and
How They Affect Flight
The Evolution of Javelin Design
Matti Jarvin - 1932
And Then Came the Scientific
Application of Bernoulli’s Principle
• Bernoulli's Principle states increased air velocity produces decreased
pressure on the top of an airfoil (top)
• Lift is produced by an airfoil through a combination of this decreased
pressure above the airfoil and increased pressure beneath it (bottom)
Credits - AVStop Magazine Online,
Helicopter Handbook
1986 Rule Change
2011-2012 NCAA Rule Book
Maximizing Aerodynamic
Gaines
Release velocity and aerodynamic efficiency
are not correlated. Therefore, additional
distance can be gained independent of release
speed by maximizing aerodynamic efficiency.
Aerodynamic gains are achieved by increasing
lift and decreasing drag simultaneously
Optimizing Release Angles
The javelin’s vertical orientation angle
describes the angle of the javelin in relation
to the ground. The angle of attack is the angle
between the release speed the vertical
orientation angle of the javelin
Optimizing Release Angles
The javelin’s horizontal orientation angle
describes the direction of the javelin to the
left or right. The angle of sideslip is the angle
between the release speed and javelin’s
horizontal orientation.
Creating Lift
By utilizing a negative horizontal javelin angle
and adding a slight negative sideslip angle in
combination with a clockwise rotation about
the javelin shaft, additional lift can be created.
The rotation of the javelin causes air hitting
the side of the javelin to increase the air flow
over the top of the javelin, decreasing air
pressure, and creating lift as described in
Bernoulli's Principle.
Decreasing Drag
A small angle of attack reduces the surface area
exposed to the air. A throw with a 0 degree angle of
attack creates 10 times less drag than a javelin thrown
with a 10 degree angle of attack. If all other variables
remain consistent, this translates to a 7 meter
difference in the throw’s distance.
Decreasing Drag
Similarly, increasing
sideslip angles also
increases drag.
Decreasing Drag
Rotation about the long axis of a javelin can
also reduce drag. Just as the spinning wheels of
a bicycle keep it from tipping side to side, the
spinning of the javelin around
the long axis helps it to resist
forward rotation. The
spinning of the javelin also
stabilizes the vibration in the
shaft similarly to how the
rifling of a gun stabilizes the
bullet.
Angular Velocities and
Aerodynamics
Angular velocity about the center of mass in
the vertical plane (forward rotation) should be
no greater than 9 degrees per second.
Rotation faster than this, cancels out gains due
to lift. A throw rotating at 18 degrees per
second will result in a throw roughly 25m less
than a throw rotating under 9 degrees per
second.
Angular Velocities and
Aerodynamics
Angle of attack also affects angular velocity. A
positive angle of attack creates drag on the
underside of the tail and will cause the javelin
to pitch forward. A negative angle of attack
creates drag on the top side of the nose and
will not cause the same pitching reaction.
Angular Velocities and
Aerodynamics
Trunk Tilt Angle
The trunk tilt angle
represents the lean of
the torso relative to
true vertical. It
describes the
orientation of the trunk,
the line of the hips and
the shoulders.
An excessive trunk tilt angle will result in an increase
in angular velocity
Angular Velocities and
Aerodynamics
Drills that address excessive angular velocity in the
vertical plane due to trunk tilt by setting up an
effective block:
1) Sprint drills to promote good running posture
2) Transition Drill to set up good posture in the cross overs
3) Special Strength Drills for the C Position (Square throws,
Three Step Tire Drills, Static Holds)
4) Staggered Square Drills to promote proper hip position in
the block
Angular Velocities and
Aerodynamics
Similarly, angular
velocities in the
horizontal plane also
effect aerodynamic
efficiencies. The greater
the horizontal rotation,
the faster the angle of
sideslip will increase.
Christian Nicolay
Angular Velocities and
Aerodynamics
Drills to address excessive angular velocities in the
horizontal plane do to shoulder Rotation:
1)
2)
3)
4)
Pullie Drill
Poll Drill
Basketball Throws
Reverse Pulls
Maximizing Release Velocity
Release velocity is directly correlated to a
throw’s distance. There is both a horizontal
and vertical component to release velocity.
Because humans are far more efficient at
creating horizontal speed, vertical speed
should only be increased so long as the
horizontal component isn’t diminished.
Technical Elements Affecting
Release Velocity
Temporal Rhythm
1. Time of throwing procedure (time from
contact of the last right foot to release)
2. Time of the single support phase (time spent
on the last right foot until the left foot hits)
3. Time of the delivery phase (time from left
foot contact to release)
Technical Elements Affecting
Release Velocity
Maintenance of Runway Speed Through the
Throwing Procedure
Jan Zelezny
Technical Elements Affecting
Release Velocity
Drills that Address Inefficient Maintenance of
Runway Speed:
1) Running Mechanics to address posture in the
carry and transition phases of the throw
2) Crossover drills addressing posture and
stride length, and footfall frequency
3) Right foot action (Soft Step): One step off a
low box, 3 step off a low box, down hill
throws
Technical Elements Affecting
Release Velocity
Left Lower Extremity Angles
1. Left knee flexion angle - left leg should be straight
at during the delivery phase
2. Left leg angle – the angle should increase in the
delivery phase
Technical Elements Affecting
Release Velocity
Hip Shoulder Separation
Hip shoulder separation represents trunk
twist. Trunk twist is used to convert linear
motion to rotational. It can also be very
effective in increasing the speed of each body
segment in order away from the trunk out to
the javelin in a whipping motion.
Technical Elements Affecting
Release Velocity
Efficient Summation of Joint Speeds:
the Whipping Action
Technical Elements Affecting
Release Velocity
Drills Addressing Efficient Summation of Joint
Speeds:
1) Hip activation drill series (low, mid and high
positions)
2) Leverage drills (double arm wall drill, single
arm wall drill, alternate wall drill, one or two
hand square throws with medicine ball, turbo
javelin, or javelin)
Additional Elements Affecting
Distance
1. Height of Release - as high as possible without
reducing speed
2. Angle of Release – between 29 and 35 degrees to
maximize speed of release and lift.
Tom Petronoff
Special Thanks To:
Steve Leigh, M.S.
And
Bing Yu, Ph.D.
Center for Human Movement Science
Division of Physical Therapy
The University of North Carolina at Chapel Hill
Under the USATF Scientific Services Project
For providing the biomechanical analysis of the javelin throw cited in this
presentation.