Foam Plate & Plastic Straw Gliders

	Foam Plate and Plastic Straw Gliders

	by Bill Kuhl http://www.scienceguy.org

Ideas and Inspiration

In my presentations lately I have been talking much about “ideas and inspiration”. The FPG9 foam plate glider
designed by Jack Reynolds has been a huge inspiration for me to expand on the idea of quick to build gliders built
primarily out of foam. I was introduced to this simple glider through the activities of the Academy of Model Aeronautics and their Aerolab program. From their inspiration I have introduced the FPG9 to other people including a local hobby shop owner Kevin Guy who has introduced the FPG9 to hundreds of young people. The Civil Air Patrol has recently partnered with AMA and is inspiring thousands of young people with ideas in aviation.

Instead of a gradual progression of difficulty, I jumped ahead to a more ambitious foam gliders first the Foam Jet II
and then the Hammer Down Catapult Glider. My thoughts lately have turned to creating gliders from only foam
plates and plastic straws held together with masking tape.


	The FPG-9 by Jack Reynolds was my main inspiration for building new designs of foam gliders.		Slightly modified version of FPG-9 glider. The vertical fin is shaped different and the penny is taped to the area of the bulge in the front. This gives the wing a slightly wider chord.

Why This is a Great Activity

* Very inexpensive and easy to find materials.

* Most people are thrilled to build something that flies.

* Gliders can be flown in fairly small areas indoors such as hallways, lunch rooms, theatre, or classrooms.

* Safe to build and fly only a scissor needed for tools.

* Much can be learned from doing small adjustments about aerodynamic theory.

* This can be a very creative activity.

What are The Very Basics A Glider Needs to Fly

Lift – the majority of the lift for the glider will come from the wing, if the wing has a slight curve in it, known as
“camber”, the lifting force will be greater. If the curve is too great, the wing will generate too much drag
and the glide will not be good. A flat wing will generate lift but not as well as a wing with some camber.

Stability – the glider needs some stability to fly through the air in a fairly level manner. Without stability
it would tumble or dive straight into the ground. For your gliders you will need the glider to balance at
close to a spot 1/3 of the width of the wing back from the front of the wing. For less conventional type
gliders such as flying wing or canard (tail first) this will be different.

To keep your glider from tipping too much from side to side stability is normally achieved through “dihedral”
which is where the wings angle upwards from the center out to the ends of the wings. Sometimes the center
of the wing is flat but it angles upward just towards the ends of the wing.

Lift : Different Airfoils Will Affect Properties of Lift


	Flat Plate airfoil simple but not the best performing airfoil.		Airfoil for gliders will typically look like this with just a slight curve.


	Airfoil with this much curve (camber) would created too much drag for a good glide.		Another method to create an airfoil is to create a bend over a straight edge.

Glider will gradually drop at an angle known as the “glide angle”. If the angle is steep the distance traveled will be short.

This illustration and the next come from a lesson plan created by Gary Hinze, known as the Simple Gliders Curriculum


	The length that a glider will travel is determined by the “lift to drag ratio” often expressed as L/D. To be more efficient the wing should produce the lift needed to keep it flying while producing the least amount of drag. Factors for drag would be the airfoil, shape and size of the wing.

Stability : Dihedral is Primary Method for Stability in Roll


			Tip Dihedral is where the center of the wing is flat and each tip bends upward.

Center of Gravity


	Gliders with a fuselage normally should balance at around 1/3 of the width of the wing back from the front of the wing. This gives the glider stability in pitch.

General Building Concepts


	Typically these are all the materials needed to create the gliders: foam plates, plastic straws, masking tape, and clay.

Tools


	The only tool really needed are scissors for this project.		To draw straight lines it can be helpful to have rulers.

More About Materials


	To build a bunch of gliders you will probably need to purchase the straws at a grocery store. These straws might be shorter than the ones found at fast food outlets but it is easy to splice straws together.		There seems to be a fair amount of difference in the cost of masking tape, the cheaper prices seem to be where it is sold in paint department.

Ideas for Wing Shapes

Even with the limited amount of useable foam in a 9” foam plate, it is possible to make many different wings
using multiple plates. The following are some ideas I have tried.


	Using just two foam plates and splicing in the middle, it is possible to make this wing with a double taper. Looks like a good wing for a jet aircraft.		This wing is made from just two plates by creating a straight center section from one plate and the two tip pieces from another plate. With no joint in the middle this should make for a stronger wing.


	This is a glider using the double taper wing. With the straw taped to center of wing at dihedral joint it makes for a strong wing.		I have been trying to limit the foam planes I build to that which can use the 9” diameter plates easily found in any grocery store. There are 10” diameter plates but are not easily found.


	Larger sections of flat foam can be found from many sources like this foam “to go” container. Problem is most likely you will not be able to purchase these containers in grocery stores.		The flat surface area in a 9” foam plate is just shy of 5 ¾” diameter or about 17 ½” square inches.

Cutting Wing Sections From Foam Plates

On one edge you will need an almost straight edge from the plate so this will further reduce the
length of foam available from 5 ¾”. This means one wing half from a plate or possibly two wing tips
and a center section from two plates. There might be enough extra foam for in one wing half
plate for horizontal stabilizer too and from another wing half plate the vertical fin could be cut also.


	The vertical line at the left side of foam is where you need to cut the foam so it will match up with the other wing half.		There might be just enough foam from a wing half to cut out the horizontal stabilizer.


	With the left over area from one wing half there might be enough foam left to cut out the vertical fin also.		This is how the curve was put in the foam for the wing, roll a dowel on the bottom of the surface so it starts to curl.

Creating 90 Degree Tape Angles

For attaching tail surface pieces I have been using masking tape 90 degree angles instead of glue.
This is fast, safe, quick, and holds pretty well. Tear or cut a length of masking tape about ¾” long
and bend in the middle trying to touch the sticky part a minimum amount.


	This is a side view of what the tape angle should look like.		Stick one side of angle to straw side and the other sticky side should stick out level with top of the straw.


	This is how the tape should be sticking out from the straw, the top surfaces should be sticky.		The vertical fin is attached to the stabilizer by using a 90-degree tape angle on each side of the vertical fin and the tape sticking out is pressed down on the stabilizer.


	In this picture I used green masking tape and drew a dark line at the joint between vertical fin and stabilizer to better demonstrate the attachment method.		Another view looking down.

Joining Straws Together

To create a longer fuselage, straws can be easily spliced together by squeezing the end of one straw and
pushing it into the inside of another straw.


	Squeeze the end of one straw so that one side bends inward.		Push the squeezed end into the fully open end of the other straw until it will not push any farther.


	This is what the joint should look like.		Wrap masking tape over the joint where the seam between the two straws is visible.


	Wing halves are joined with masking tape joined down the center. I start with putting tape on the top first and then on the bottom. Try to get the tape to cover equally each wing half down the middle and raise one wing up while taping to get dihedral in the wing. Wrap around the leading and trailing edge slightly. Use another length of tape across the bottom.		Bend two lengths of masking tape the width of the wing at a 90 degrees down the middle to serve as a bracket to attach the plastic straw fuselage to the center of the wing.


	If the wing is on top of the fuselage, I would suggest a small foam shim be placed between the bottom of the wing and the straw fuselage		Straw glider will need some nose weight to achieve proper Center of Gravity balance point. Press the clay into the end of the straw, it easy to add or take away small amounts of clay to get the correct balance point. You may wish to remove a tiny amount of clay and tape over the clay so it does not fall off.


	Completed glider, be sure to read instructions on launching and adjusting.

Launching Foam plate and Straw Gliders

Gliders made from foam plates and straws most likely will not handle a toss with a large amount of speed.
The foam and plastic straw will flex at high speeds and make consistent trim adjustments difficult. Your
gliders will be better launched level with medium force. If you can find a balcony which provides a safe
place to launch your glider from a higher altitude that works really well.


	Gripping the straw underneath the wing is slightly difficult so I created a tab from masking tape doubled over to grab when launching.		Glider launch tab grasped between thumb and forefinger, release at this point level or slightly down.


	If the glider has too much lift the nose will rise up until the angle of attack increases too much causing the glider to loose lift. At this point normally the nose will drop and the glider will go into a dive.		If the glider is balanced with too much weight ahead of the CG or the angle of attack is not great enough it may dive towards the ground.


	This glider went into a stall when launched into wind outdoors and then into a very steep dive.

Launching from a Balcony

If there is a safe spot to launch gliders from such as a balcony it gives for a longer flight and a better chance to
observe the flight characteristics. It also gives the glider greater potential energy.

Making Adjustments to the Flight Path - Trimming

Tiny adjustments can be made to the tail surfaces of the glider to change the flight path of the glider.
By bending the rear edges of the foam on the vertical fin for turning or the rear of the stabilizer for changes in pitch. Adjustments to the foam need to be really tiny with deflection from straight being no more than 1/16”.

The rear edge of the vertical fin that moves is known as the “rudder”. Bending the rudder trailing edge
towards the right should alter the flight path to the right. Bending to the left will cause the opposite reaction.

The rear end of the horizontal stabilizer can be adjusted up or down also which is known as the “elevator”
on airplanes with movable surfaces. Bending the surface upwards should cause the glider to climb, bending
down will do the opposite.


	For right turn bend rear edge of vertical fin towards the right by a tiny amount. Bend to the left for left turn.		Bend the rear edge of the horizontal stabilizer upward if the glider is diving in the glide. Bending downward if the glider is stalling.

More Ideas for Gliders


	This is a “canard’ glider which means the small wing is in front. The Wright Brothers used this configuration on all their gliders and powered airplanes.		Using three foam plates it is possible to make a flying wing glider with a much longer wingspan. This is known as “high-aspect ratio” and improves the efficiency of the glide beyond just adding wing area.


	Ideas for simple foam gliders can come from anywhere, I just received a radio control glider kit the “Alula” which has a shape like a hawk. With some foam plates I created a free flight glider with much of the same look.		Using more area from the foam plate by using part of the curved portion of the plate.

Student Designed Gliders


	Student designed and built gliders for College for Kids class.		This glider flew pretty good when launched from balcony.

Educational Aspects


	Potential Energy – the altitude above the ground gives the glider potential energy as gravity pulls it along the glide path.		Kinetic Energy – after the glider is launched the mass of the glider moves with the kinetic energy given to it by the throw and the glide down the glide path. Drag will oppose this force.

Giving Your Glider a Rubber Motor

Someone suggested my foam plate and plastic straw gliders would be better with a propeller so I added one. To make the plastic straw fuselage stiff enough I pushed a small bamboo skewer inside the straw. The propeller is from a Guillow balsa plane, needed to stuff some cardboard in rectangular part to make a tight fit over the straw. It flies good across the living room, hope to try it outside soon.

Video of Plane Flying

I built another larger plane and also built the propeller from a cottage cheese container and a couple of paperclips. Flies well but I think I can improve on the efficiency of the propeller.

youtu.be/ApXFzfYvwXo Video of this plane flying

New Video 5/8/2013


	Launching gliders converted for rubber power at Wisconsin Afterschool Conference 2013.	Teachers building foam plate and straw gliders. See link below for blog article with more details from this event.

Blog Article with pictures on teaching this project

Additional Resources

* Everything you would want to know about gliding flight from NASA.

* FPG-9 Flight School Children's Museum of Indianapolis

* Download PDF version of this article.

* My Blog Article Why I Still Fly Wind Up Airplanes

* Ultimate Indoor Model Airplane F1D