What It Takes To Make A Good Indoor Glider

The indoor glider events are simple yet hard to master. When one
thinks about the events, it quickly boils down to three requirements. These
are:
1) To get the glider as high as you can or to the very top of the ceiling
2) To get the glider to transition from the high speed launch to nominal
glider speed
3) To get the best sink rate possible

Now to excel at these requirements three major issues become important.
1) Weight
2) Strength
3) Aerodynamics

Weight and Aerodynamics (airfoil) are the two important factors in
determining the sink rate. The lighter the glider, the better the sink
rate. It is very simple. Also an airfoil with a larger lift coefficient
translates into a better sink rate. Weight is the most important of these
two factors. One must remember this and build the glider as light as
possible......but
Strength is the most important factor for getting the glider high. One
must never forget that the easiest way to turn good times is to get higher.
At most contests the person who gets the highest typically gets the best
times. So one must build the glider strong enough to get to the top of
the building. The easiest way to get strength is to build the glider
heavier. The higher density balsa woods typically are stiffer and stronger.
Also if one makes the wing thicker, strength is gained. Glider height is
also influenced by aerodynamics and weight. One needs a low drag airfoil
because drag is the second most important factor in obtaining good height.
It also turns out the heavier the glider the higher it will go. But the
weight of the glider does not strongly influence the height. Also don't
forget weight is very bad for sink rate.
One can easily see that the factors which influence one important
requirement, also will influence one of the other important requirements in
the opposite direction. That is what makes gliders so challenging.
Now let's not forget about transition. Transition is influenced mainly
by aerodynamics. This time aerodynamics doesn't mean airfoils but other
things like dihedral in the wing, nose and tail lengths or moments, rudder
and elevator sizes and positions. A good design has usually worked out all
these issues. The designer has typically arrived at a design by the built
it, fly it and then build another one with some small improvements.
Some things important to note. First, how strong you are really
doesn't give you a great big advantage, especially in catapult gliders. Yes
it is easy to put more rubber on your launcher and pull back harder, and the
glider might go up a little higher, but you will be surprised how much more
force it takes to get just a little higher. Even in hand launch gliders, I
am sure I could get my glider higher then the best major league pitcher, if
he his glider was a flexible, high drag and light plane.
Second, don't worry about getting the lightest wood available on this
planet. I have some 3.5 lb/ft^3 balsa which is useless for gliders because
it has no strength. It is really a strength vs. weight ratio that you are
interested in. So if you can't find the lightest wood, don't worry about
it. Try you best to get good wood, but heavy wood used appropriately has and
can work. Yes maybe the wing thickness needs to be thinner, but remember
thinner wings equal less drag.
 

Unfortunately- Not every plane is successful!