Ideas and Inspiration
Basic Aerodynamics With a Lesson
Traditionally model airplanes have been constructed with balsa wood or a balsa framework covered with tissue or thin paper. I really like working with balsa wood; it is so easy to cut, bend, sand, and glue together. Incredibly lightweight structures can be built from balsa wood. The record duration flight for a model airplane powered by rubber flown indoors in a very large room is over one hour built from balsa with a very lightweight covering.So why use foam? Foam is light in weight, has no grain, water resistant, easy to obtain and inexpensive. The last two items were the most important to me for what I was trying to accomplish in model airplane workshops. I wanted material that was easy to obtain almost everywhere so materials that could be found at grocery stores seemed like a good bet. For that reason I have been concentrating designing model airplanes that could the common 9” diameter foam plate which is available in stores everywhere. The small amount of available foam does impose a constraint that I have been able to work around. Larger sections of foam could be in 10” foam plates or carryout containers but I wanted to design airplanes that used the foam that didn’t have to be saved or obtained food supply houses.
|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.|
Newest Video of Flight Club Glider Flights
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
“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.
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 create 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
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.
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
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.
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.
|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.|
|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.|
|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.|
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.|
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.|
Hand Launch Glider Books
More Ideas for Gliders
Student Designed Gliders
|Student designed and built gliders for College for Kids class.||This glider flew pretty good when launched from
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