model aviation an educational hobby

8/8/2019 Model Aviation an Educational Hobby

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Model Aviation Educational activity for young people. Educational activity for young people.

Presentation Placed in Public Domain by Bill KuhlPresentation Placed in Public Domain by Bill Kuhl



IntroductionModel aviation has been both an enjoyable and educational

activity for much of my life. Two ways it has helped me is

demonstrating my thinking was incorrect or inaccurate, and

learning the process of refinement. Often I thought small

changes in trim, propellers, or rubber motors would not make

much of a difference but I was proven wrong. In the processof being proven incorrect I have learned to test individual

aspects, record important data, and do the process again after

making new changes.

It is my hope that this presentation can be used to promotethe virtues of model aviation as a fun and educational activity

for young people. Feel free to copy this presentation, I only

asked that it is not sold for profit.

Bill Kuhl



History

The first rubber-powered model plane can be credited to the

French aviation enthusiast, Alphonse Penaud. Initially he

experimented with rubber-powered model helicopters but later turned to building model planes powered by rubber. The Wright

brothers were first exposed to flight by the toy helicopter their

father gave them based on the helicopter developed by Penaud.

First Rubber-powered Model Airplane

Flew 131 feet in1871.

Modern

copy of

Penaud¶sPlanophore



History

The First Aeromodeling Clubs

The first model airplane clubs started in the New

York City area as early as 1907. Balsa woodwas not used in model planes until around 1911,

so models were constructed of materials such as

bamboo, pine, and spruce.

Most models were twin pushers, two motor sticks with a prop in the rear of each, coming

together in front. Viewed from the top it looked

like a capital letter ³A´. The propellers turned in

opposing directions to cancel the effects of

torque. Twin-pusher



History

City Sponsored Model Airplane Clubs

In the 1930¶s, even city government promoted model aviation

by sponsoring contest and clubs. Detroit Department of

Recreation sponsored twenty-two clubs, and even sold

modeling supplies. School gyms were open one night a week

for indoor flying.



History

The Influence of Charles Lindbergh on Aeromodeling

Charles Lindbergh¶s historic flight from New York to Paris in

1927 was the driving force to skyrocket the popularity of

aeromodeling. Before Lindbergh¶s flight only around a dozen

model airplane kit manufacturers existed and within a year of

the flight there were over two thousand.

Spirit of St. Louis



History

Today, the largest number of young people are exposed to

free flight model airplanes by an event that is part of a competition

held in many middle and high schools known as

³Science Olympiad´. The model airplane event is now known as,

³The Wright Stuff´. Planes must be built according tospecifications that limit the size and minimum weight of the

airplane. Competitions are held at regional and national levels,

with the top times equaling what a very skillful indoor modeler

might accomplish.

Science Olympiad



Safety

Relatively safe hobby because the models are light and fly

slow.

Biggest danger is when children do not use good judgment in retrieving a model that is caught in a tree,

power line, or on top of a building.

Students need to be taught safe techniques for working

with razor blades. Another option is to pre-cut all pieces.

Safety is of primary importance for any activity for young

people. Small rubber powered planes that weigh less than

an ounce are relatively safe if used with common sense.



Building



What are t

he models made of?

Balsa Wood

The most popular material for building rubber powered

model airplanes is ³balsa wood´. It is a very fast- growing

tree which reaches a height of 15 feet in the first year, and60 to 90 feet during the next six to ten years. Most balsa

comes from balsa plantations in Ecuador owned and

operated by the Baltek Corporation of Northvale, NJ.

Although balsa may appear rather fragile, it is fairly strongfor its weight. The weight of balsa can vary considerably, for

small models the best performance can be obtained by

selecting lighter balsa.



What are t

he models made of?

Covering

Some models are constructed entirely of balsa wood, but

more often a balsa structure is covered with a paper,tissue, or plastic. The covering not only covers the

structure for flight, but also adds to the strength of the

structure.

Some models use onion skin paper as plan and coveringmaterial. This is a strong material but is also rather heavy

and can warp the structure as the humidity changes.



Building Questions

How long does it take to build a model airplane? This can

vary a lot but the simplest planes such as the AMA Cub or

Delta Dart can be completed in about an hour. Planes with

ribs in wing and tail could take considerably longer.

Can you repair the plane if it breaks? Unless a really large

truck runs over your plane, any breaks to the balsa wood

should be easily glued. A bigger problem is when the planebecomes severally warped, if the warp is bad enough,

better to build a new plane.



What Tools & Materials are Needed

The Essentials - razor blade or modeling knife, pins, and

glue.

Building Surface that pins can be pushed

into ceiling tile sections or cardboard.

Normally plans are covered with wax paper, but some planes

use the plan as the covering material.

Helpful to have a sanding block.

Gluestick is used to attach covering material to balsa

framework.



What Tools & Materials are Needed

Winders

Essential to get flying times of more than a few seconds, is

a mechanical winder. The rubber motor is stretched and

lubricated, and turns are wound in as the winder is broughtcloser to the other end of the rubber loop. Common ratios

for winders are; 15:1 and 5:1.

5:1 Winder 15:1 Winder Armorall can be

used as a lubricant



Flying



Free

Fligh

t

The cost of simple rubber-powered airplanes is low, but

that is not why they are known as ³free flight´, it isbecause they do not have any external control. The

flight path is controlled by the trim adjustments in the

model, the stability built into the model, and how the

wind blows.



Where can these models be

flown?

Flying indoors in a gym

is a year-round activity.

Models can be flown outdoors

when the breeze is very light.



Indoor Flying Gallery



Outdoor Flying Gallery



Educational As pectsI owe as much, if not more, to my uncle who introduced me

to model airplanes when I was a kid 30+ years ago than I

do to any of my university professors in helping me to

become the knowledgeable structural engineer that I am

today.

Thanks Uncle Tom.

Cliff

I know what you mean Cliff. I had an uncle who gave me a

model airplane kit at Christmas time when I was maybe 9

years old. I thought it was a very big deal. This same unclelater gave me his old Boy Scout Manual. That uncle

probably had a bigger influence on my life and the way I

turned out than anyone else, even my parents.

Ed



Educational As pects

Accuracy

Building and adjusting the model accurately can make

a huge difference in the performance. As you buildadditional models, you will want to improve the

accuracy of your work for aesthetic reasons. Hopefully

this desire to do more accurate work will transfer into

all areas of your life.




Creativity

Designing and building your model airplane is rather easy to

do. With some understanding of aerodynamics and using

³rule of thumb´ proportions, anyone can design a successful

model.

There are many more unusual types of aircraft that can

provide additional challenges such as flying wings or

³canards´ (tail first).FlyingFlying

WingWing

aircraft inaircraft in

flightflight

indoors.indoors.




Test Theories

Even the simplest model plane, flies according to the

principles of aerodynamics and physics. Often the³common sense´ ideas we have on the factors that affect

flight performance are proven inaccurate. Small changes

can make a huge difference; hopefully model aviation will

open your mind to new ways of thinking.




Mathematics - Example calculation of winder turns.

Maximum turns per inch for 3/32" rubber is 129, for our

rubber motor 10" long, maximum turns would be 1290. For sport flying 80% would result in 1032 turns.

129 x 10 = 1290 1290 x .8 = 1032

Once we know the total turns, it is easy to calculate the total

cranks of the winder needed. Simply divide the total turns

by the ratio of the winder.

For example using the 5:1: 1032 / 5 = 206.4, truncating to a

whole number would be 206 winder turns.




Physics

How Does the Rubber Motor Work (in terms of energy transfer)?

When you crank the winder, mechanical energy is converted to

potential energy stored in the rubber . To be more precise, this

is elastic potential energy . Harcourts Dictionary defines elastic

potential energy as "the energy made available for use by the

return of an elastic body to its original configuration."Potential energy of the wound rubber is converted to kinetic

energy of the spinning propeller. Harcourts Dictionary defines

kinetic energy as "the energy inherent in the motion of a body"



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