Basic Principles of the Stunt Hemisphere by Keith Renecle 7th July th July 2006 Belgrade, Serbia

C/L Stunt is Precision Aerobatics!

Basic principle Pilots who perform closest to the rules should score the highest points

What does this mean?

Pilots and judges and judges must have a good understanding of the rules

What does this mean? Pilots and judges and judges must have a good understanding of the rules

What does this mean? Pilots and judges and judges must have a good understanding of the rules Pilots and judges must have the same understanding of the rules

What does this mean? Pilots and judges and judges must have a good understanding of the rules Pilots and judges must have the same understanding of the rules

This is a SUBJECTIVE sport!

We must ensure that we do not use SUBJECTIVITY as an excuse for a lack of understanding! We must ensure that we do not use SUBJECTIVITY as an excuse for a lack of understanding!

What can we do to help?

Benefits of using 3-D graphics in C/L Stunt

Competitors: A greater correlation between words and illustration

Benefits of using 3-D graphics in C/L Stunt Competitors: A greater correlation between words and illustration WORDS create mental expectation

Benefits of using 3-D graphics in C/L Stunt Competitors: A greater correlation between words and illustration WORDS create mental expectation ILLUSTRATIONS create visual expectation

Benefits of using 3-D graphics in C/L Stunt Competitors: A greater correlation between words and illustration WORDS create mental expectation ILLUSTRATIONS create visual expectation Conflict in expectations creates confusion

Benefits of using 3-D graphics in C/L Stunt Judges: Understanding of shape of manoeuvre on sphere as viewed from outside

Benefits of using 3-D graphics in C/L Stunt Judges: Understanding of shape of manoeuvre on sphere as viewed from outside Manoeuvres need to be flown accurately from pilots view. Judge must therefore correlate what is seen with what the pilot sees.

TECHNOLOGY The present: (Basically no technology!)

TECHNOLOGY Competitor expectation conflicts with judging result:- has always existed.

TECHNOLOGY The FUTURE!

TECHNOLOGY Although possible now….. Costs will be prohibitive.

TECHNOLOGY The present: Conflict between mental expectation created by words, and visual expectation created by drawing:- has always existed

TECHNOLOGY The present: Conflict between mental expectation created by words, and visual expectation created by drawing:- has always existed Technology to address this conflict:- Affordable and available today

Use this technology effectively to minimise conflict Create consistent mental & visual expectation for judge & competitor

Use this technology effectively to minimise conflict Create consistent mental & visual expectation for judge & competitor Provide consistent training tool to judge & competitor

Use this technology effectively to minimise conflict Create consistent mental & visual expectation for judge & competitor Provide consistent training tool to judge & competitor Create consistent understanding of manoeuvre appearance on sphere

This presentation shows what is possible now!

With 3-D graphics we can: See how the manoeuvres fit the sphere View the manoeuvres from any angle or position in the virtual world Watch them being performed in real time

Here are a few screenshots from the CL Sim-1

Basic Principles of our Stunt Hemisphere

Why do we have misconceptions about the stunt manoeuvres?

Pitch

Roll & Yaw

It should be dead easy…………. just like golf! All you basically have to do is hit a small white ball into 18 different holes……… How difficult can that be?? How difficult can that be??

How do we go about judging the pattern?

It is obviously important to know exactly how the manoeuvre shapes look, and how they will appear from the various angles. It is obviously important to know exactly how the manoeuvre shapes look, and how they will appear from the various angles. How do we achieve this?? How do we achieve this??

Judges need a good understanding of the principles that govern our stunt hemisphere Judges need a good understanding of the principles that govern our stunt hemisphere

Judges Guide 4B.4 Judging focus 1. Shape 2. Size 3. Intersections 4. Bottoms

Judges Guide 4B.4 Judging focus 1. Shape 2. Size 3. Intersections 4. Bottoms

The flight path of a tethered object like a C/L model

C/L Manoeuvre shapes They are just shapes drawn on the surface of spheres

C/L Manoeuvre shapes They are just shapes drawn on the surface of spheres The shapes are not dependent on how we view them

C/L Manoeuvre shapes They are just shapes drawn on the surface of spheres The shapes are not dependent on how we view them They are shapes governed by the rules of spherical geometry

C/L Manoeuvre shapes They are just shapes drawn on the surface of spheres The shapes are not dependent on how we view them They are shapes governed by the rules of spherical geometry

To understand the stunt hemisphere, we need to understand the following:

Basic principles of lines and paths on spheres To understand the stunt hemisphere, we need to understand the following:

Basic principles of lines and paths on spheres How these paths apply to manoeuvre shapes To understand the stunt hemisphere, we need to understand the following:

Basic principles of lines and paths on spheres How these paths apply to manoeuvre shapes How the manoeuvres fit on the surface of the sphere To understand the stunt hemisphere, we need to understand the following:

How are shapes made up?

F2B Rule book

How are shapes made up? Flat plane geometry

3-D Object

3-D objects can be manipulated

Rules of spheres 1. All lines on spheres surface are circles

Rules of spheres 1. All lines on spheres surface are circles 2. There are 2 types of circles: Great Circles Minor circles

Mathematical definition Any plane section of a sphere is a circle. That is, slide a plane along in space like a knife. If you slice off a piece of a spherical shell, the edge that is exposed will be a circle. If the slicing plane goes through the center of the sphere, the exposed edge will be a great circle, otherwise it is called a minor circle.

The Great Circle

The Minor Circle

There are NO straight lines on the surface of spheres

The spherical equivalent of a straight line, is the great circle path.

There are NO straight lines on the surface of spheres The spherical equivalent of a straight line, is the great circle path. It is the shortest distance between two points on the surface of the sphere.

Great Circle path

FAI rule definition of Straight line Means the closest distance between two points as seen in two dimensions. These words are marked with inverted commas throughout to provide a constant reminder that the requirement (in all the square and triangular manoeuvres for example), is for a number of turns ("corners") which should be joined together with flight paths which appear to be straight lines when seen by the pilot.

The Spherical Straight line The shortest distance between two points

The Spherical Straight line The shortest distance between two points A path with no change in direction or heading

The Spherical Straight line The shortest distance between two points A path with no change in direction or heading Question: Is flying around parallel to the ground at 45 degrees a straight line?

Why do we need to understand this point so well?

These two distinct paths will project very different shapes from almost any point of view.

Why do we need to understand this point so well? These two distinct paths will project very different shapes from almost any point of view. These two distinct paths are not interchangeable. These two distinct paths are not interchangeable.

Interesting Sphere facts There are NO parallel great circles

Interesting Sphere facts There are NO parallel great circles Minor circles can be parallel

Interesting Sphere facts There are NO parallel great circles Minor circles can be parallel In plane geometry, there are no interesting polygons with only 2 straight sides

Polygons

Interesting Sphere facts On the sphere surface, a polygon can be formed by 2 great circles ie. 2 straight sides

Global mapping

How does all this apply to our stunt pattern?

Minor circle paths = Cone

Loops are cones

Figure eights = 2 cones

The straight side shapes How do they look on the sphere?

The straight side shapes

The hourglass

FAI rule definition of Straight line Means the closest distance between two points as seen in two dimensions. These words are marked with inverted commas throughout to provide a constant reminder that the requirement (in all the square and triangular manoeuvres for example), is for a number of turns ("corners") which should be joined together with flight paths which appear to be straight lines when seen by the pilot.

The present FAI rules are written from the pilots viewpoint

Some good reasons: The pilot is at a constant distance from the spheres surface. (fixed by line length)

The present FAI rules are written from the pilots viewpoint Some good reasons: The pilot is at a constant distance from the spheres surface. (fixed by line length) The pilot sees the manoeuvres with the least spherical distortion.

The present FAI rules are written from the pilots viewpoint Some good reasons: The pilot is at a constant distance from the spheres surface. (fixed by line length) The pilot sees the manoeuvres with the least spherical distortion. Vertical always looks vertical to the pilot.

Seeing things in perspective

There are various drawing views:

Seeing things in perspective There are various drawing views: Plan or orthographic views Isometric views Perspective views

Plan or orthographic view

Isometric view

Perspective view

Orthographic versus Perspective

Orthographic Vertical 8

Perspective view of Vertical 8

Charles Mackeys Stunt judging machine

Whats the big deal? Does it really make any difference?

What do you think?

How do we see things?

Peripheral vision: 120 to 140 degrees wide

How do we see things? Peripheral vision: 120 to 140 degrees wide Peripheral perception: What we do with the info that we see Eye/hand co-ordination e.g. Tennis players, racing drivers etc.

How do we see things?

What is the Pilots view?

It is close to a view from the geometric centre of the sphere

What is the Pilots view? It is close to a view from the geometric centre of the sphere Depends where the pilot holds the handle

What is the Pilots view? It is close to a view from the geometric centre of the sphere Depends where the pilot holds the handle Viewing distance is fixed by the length of the lines, and is almost like viewing a flat plane

CAUTION!! The surface of the sphere from the pilots view is NOT the same as a flat surface!

CAUTION!! The rules of spheres still apply. Minor circles remain minor circles Great circles remain great circles

CAUTION!! The surface of the sphere from the pilots view is NOT the same as a flat surface! The rules of spheres still apply. Minor circles remain minor circles Great circles remain great circles The pilots view is still a perspective view

The orange test

The Pilots view

The Square manoeuvres!!

Judges Square

Judges Square 8

Great Circle Square

Great Circle Square 8?

GC & MC Square

GC & MC Square Vertical 8

FAI square

FAI square 8

FAI square judges view

FAI square 5 ft. corners

Can our models turn a 5ft. radius corner?

Loren Nell

FAI square 16 ft. corners

How close to the rulebook shapes are the top fliers flying??

Ted Fancher

Billy Werwage

Serge Delabarde

Summary All our manoeuvre shapes are spherical

Summary The shapes are independent of of how we view them

Summary All our manoeuvre shapes are spherical The shapes are independent of of how we view them We need to learn to understand these principles

Summary All our manoeuvre shapes are spherical The shapes are independent of how we view them We need to learn to understand these principles This 3-D software shown here can help to enhance our training methods, and is freely available.

Where to from here?

Work together to ensure a common understanding of the manoeuvre shapes

Where to from here? Work together to ensure a common understanding of the manoeuvre shapes Correct the basic problems in the rules

Where to from here? Work together to ensure a common understanding of the manoeuvre shapes Correct the basic problems in the rules Develop a judges training system

Thank you for attending this workshop