In this instructable, I will not only show you how to make a hand-thrown glider of these proportions:
Wingspan: 20 inches (50 centimeters)
Length: 20 inches
Height (including vertical stabilizer): 7 inches (18 centimeters)
Weight: 98 grams (3.45 ounces)
but, with the ratios I will give you, you can make whatever size glider you like (within an acceptable hand-throwing range of size).
If you have any questions, about the ratios, or the building of the plane featured here, or your own, (or whatever else you can think of, as long as it has to do with hand gliders) feel free to leave them in the comments and I'll get to them as soon as I can.

For this instructable you will need the following items and materials: (look at photo 2) You will also need a protractor for step 6.

If you just want to make the plane: Just look at the pictures and all explanations in BOLD font in the following steps. If you want to build a plane of your own size , follow all explanations in regular font and some of the pictures (as directed) in the following steps.

I chose cardboard to build this plane because it is cheap and readily available, and i had plenty around. However, if you want to make this plane, but you don't have enough cardboard (you need a piece with a total area of about 375 inches squared, with the minimum dimensions of 25x15, so you have enough room), if you have enough styrofoam of the same thickness, use that.

I strongly recommend that you use a sharp knife, such as an exacto, to cut out all parts of this plane or any other you may build for the following reasons:
- scissors can be bulky and use leverage to cut, which may cause a risk of bending the cardboard, resulting in a floppy, almost useless wing or fuselage, that fixing will only add weight which is the last thing you want when building these hand gliders.
- knives tend to be sharper than scissors and their thin blades can cut clean edges, are easier to handle than scissors, and are more accurate, which makes all the difference in factors of flight such as drag, wing area, and weight.
For the right cutting technique, refer to photo 3.
Cut the first two layers of the cardboard, then bend open the cut and slice through the last layer. As I said before, be very careful when cutting, you don't want to bend the cardboard, this weakens it immensely, and you end up with a floppy piece of junk.

For the two important terms that you will need to know when building this glider or your own, refer to photos 4 and 5.

All dimensions I give are measured in inches.

Step 1: The Main Wing

The dimensions of the main wing are 4 inches (the wing chord) by 20 inches.
Mark the dimensions, as shown in photos 1 and 2.
(All other photos have explanations.)

If you are making your own plane, the size of the other parts, the vertical/horizontal stabilizers and fuselage, are always determined by the ratios that are based upon the size of the chord and area of the main wing. Don't worry if this sounds complicated, I will display the calculations for explanation. Because the main wing determines the size of the other parts, once again, I STRONGLY recommend that the dimensions that you choose for the chord and the wingspan are EVEN numbers.

Of course, for example, a plane with a square wing would take a longer fuselage and be more complicated to build and balance. So, for a basic rule, the chord size should be a fifth of the size of the wing span (1x5,2x10,3x15 etc.), as mine is, because you will end up with easy, even measurements for dimensions of the other parts. For a very good technique when drawing the dimensions if you are using cardboard as your material, look at photo 3. If you want to use a different material, I suggest to use styrofoam of the same thickness.

After making the wing, always mark the center and draw a line down it to make it easy to position for mounting.

Step 2: Horizontal Stabilizer

The dimensions of the horizontal stabilizer are 2 inches by 8 inches. Draw the cutout pattern as shown in photo 1, and cut it out as directed in the intro. Refer to all photos.

This is another easy part. The area of the horizontal stabilizer should be a fifth of the area of the main wing.
Using the basic rule to find the dimensions of the main wing as shown in step 1, lets use the example of a main wing with dimensions 6x30. 6x30 = 180 square inches of main wing area. 180/5 = 36 square inches of horizontal stabilizer area. Simple as that.

But, of course, you still have to determine the dimensions of the horizontal stabilizer. The easiest way to do this is by finding all the common factors of the number you end up with, so in this example, 36. I used this factorization calculator: http://www.calculatorsoup.com/calculators/math/factors.php

They are: 1,2,3,4,6,9,12,18,36

Possible horizontal stabilizer dimensions:
1x36
2x18
3x12
4x9
6x6

Choose the dimensions that will give you THE WIDEST CHORD WITHOUT SACRIFICING A LONGER SPAN,
so in this example: 3x12.
This will ensure that you always have a proper rectangular wing shape.
Make a cutout pattern with the dimensions, cut it out, and mark a line down the center as you did with the main wing.

Step 3: Building the Fuselage

Fire up the glue gun, you will need it at the end of this step, and for the rest of the instructable.
This part may be a bit more difficult for you as well, because I always integrate (make part of) the vertical stabilizer into the main fuselage, as this will prevent you from having to glue one on and add extra weight. You will have to make two and glue them together for adequate strength if a crash were to happen. Refer to photos for further directions.

This is where it gets a bit more complicated for you. This is because (as said above) I always integrate the vertical stabilizer into the
fuselage. The length of the fuselage must be 4 to 6 times the chord of the wing. I chose the in - between value: 5 times the length, because it worked out perfectly for the plane featured here. Of course, a plane with a larger wing will need a longer fuselage, and a smaller wing will need a shorter fuselage. Use the value that works best for your choice of wing size.

Using the example of the wing before with dimensions 6x30: The chord is 6 inches. 6x5 = 30 So, basically, the length of the fuselage should be the same as the span of the wing, unless you use the values 4 or 6.
Also, the longer the fuselage is, the easier the plane is to balance. So if you want to use the value of 6, go right ahead: (using the same example as before) 6x6 = 36 inch long fuselage -------> easier to balance plane.

The height of the fuselage should be half the chord of the wing. So, the dimensions of the fuselage in this example:
Length: 36 inches Height: 3 inches
Now that we have determined the dimensions of the fuselage, we have to add the vertical stabilizer.
The area of the vertical stabilizer must be a tenth of the area of the main wing. Main wing area: 180 square inches 180/10
Total vertical stabilizer area: 18 inches squared
To find the dimensions, simply use the same method with the common factors that you used to find the dimensions of the horizontal stabilizer. So, in this case: 3x6

Now, look at photo 1 on how to make a cutout pattern, just ignore the measurements and put in your own that you have figured out.
If you are building with cardboard, then you will have to make two of the same fuselages, and glue them together with SMALL STRINGS of glue in the same pattern as shown in photo 6, in order for enough strength, without too much added weight. The same thing applies for styrofoam of the same thickness, unless you have 1/4 inch thick styrofoam.

Step 4: Puting the Wings On

The first wing that will be mounted is the main wing, then the horizontal stabilizer. But first, cut a slot for the horizontal stabilizer, as show in photos 1 and 2. Refer to photos for all directions.

This is the most complicated part, because it involves 2 ratios, in order to find the best positioning for the main wing that will require the least weight for the most balance. One ratio will determine the distance from the front of the fuselage to the front of the main wing, and the other will determine the distance for the back of the main wing to the front of the horizontal stabilizer. Both ratios are based upon the chord of the main wing.

To make it easier, first cut a slot in the rear of the fuselage for the horizontal stabilizer. Mark out a cutout pattern the size of the horizontal stabilizer (chord and width of material), halfway up the height of the fuselage, and cut it out. For reference, look at photos 1 and 2.

Now that you know where the horizontal stabilizer is positioned, you can mark the position of the main wing. Place a measuring tape over the fuselage, as shown in photo 4.
Here are the ratios for positioning the main wing:
1st distance:
The distance from the front of the fuselage to the front of the main wing should be between 1inch for every 1 inch of main wing chord and 3 inches for every 2 inches of main wing chord.
2nd distance:
The distance from the back of the wing to the front of the horizontal stabilizer should be between 2 inches for every 1 inch of wing chord and 3 inches for every 1 inch of wing chord.

Your going to have to try to balance the 2 distances as much as possible, with the 1st being slightly greater than the 2nd distance. To reduce the weight needed to balance a bigger plane, the main wing will need to be placed as far back as possible, without the 1st distance exceeding the 2nd distance. On a smaller plane, the 2nd distance must exceed the 1st distance to prevent too much tail weight. In order to balance the ratios properly, you must first know the distance from the front of the fuselage to the front of the horizontal stabilizer.

Because I don't know the dimensions you have picked, I can only give you the best ones for explanation of how it would work for a larger plane and smaller plane.

Larger plane:
Main wing dimensions: 6x30
Chord of horizontal stabilizer: 3 inches
Fuselage length: 30 inches
Distance from front of the fuselage to front of horizontal stabilizer: 27 inches.
27-6 = 19 inches to work with for balancing.
Possible main wing position:
Front of fuselage to front of main wing: 7 inches    Ratio used: 1.1665:1    !!!!!!???
Back of main wing to front of horizontal stabilizer: 12 inches     Ratio used: 2:1

Smaller plane:

Main wing dimensions: 2x10
Chord of horizontal stabilizer: 1 inch
Fuselage length: 10 inches
Distance from front of the fuselage to front of horizontal stabilizer: 9 inches
9-2 = 7 inches to work with for balancing.
Possible main wing position:
Front of fuselage to front of main wing: 3 inches   Ratio used: 1.5:1
Back of main wing to front of horizontal stabilizer: 4 inches Ratio used: 2:1

Thats only two possible examples for main wing positions that I have shown you, out of thousands more that are also possible.
Multiply that by the possible plane sizes based on the rules and ratios I gave, and you get thousands more of possible combinations of the ratios to make wing positions.

You probably haven't thought that building a "simple" hand glider could be that complicated. However, if you are stuck, once again, don't hesitate to leave a question in the comment box, and if you want me to recommend a wing position to you, type down the dimensions of the main wing, the fuselage (length and height), and horizontal stabilizer. I'd be happy to help.

Once you have marked out the position of the main wing, extend the markings as far as possible, upwards and downwards.
Here is the point where you have some choice:
You can either cut a slot for the main wing or glue it on the top/bottom of the fuselage. I recommend cutting a slot in the center of the fuselage, between the markings, for the most strength with as little added glue as possible. Then tape it to keep it in position, and add two large blobs of glue on all 4 sides of the wing against the fuselage. However, if the height of the fuselage does not exceed 1 inch, tape it on the top or bottom, adding two small beads of glue on either side of the tape. ALWAYS make sure that the wing is straight, centered, and square to the fuselage before glueing. Same with the horizontal stabilizer. Tape it into position from the bottom as shown in photo 9, and add 2 small strings of glue on either side of the vertical stabilizer, as shown in photo 10, for added strength.

Finally, you can move on.

Step 5: Adding Weights

The ideal amount of nose weight for this plane is 20 grams. This can be achieved byglueing 4 nickels and 2 pennies in 2 stacks, as shown in photos 1 and 2. If you don't have my currency, or prefer to use less valuable objects as weighting, then just find an object that weighs 20 grams and divide it in half, or find two equal sized objects that weigh the same and add up to 20 grams. A kitchen scale (electronic or mechanical) is handy to have here. Glue them about half an inch from the front of the plane, as shown in photo 3.

Once again, because I don't know the size of the plane you are building, I cannot tell you how much weight it will require to balance it. I can, however, tell you a method that will make finding the amount of weight your plane requires quite easy. I call it the "Finger Axis" technique. How to do it:

Place your 2 index fingers on both ends of the main wing, 2/3 of the way down, as shown in photo 4.
Lift the plane in the air with your 2 fingers, but don't increase pressure with you fingers, just press gently, to allow the plane to swing on your fingers freely.

Of course, if you haven't added weight, the plane's tail is just going to hang down the first time you lift it. This is the point where you keep on taping on more and more weight, testing the plane for balance as you tape more on, until you get the proper balance. Look at photos 3,4, and 5 for reference. Make sure you tape equal size weights to either side of the fuselage. You can choose different things as objects for weight, but make sure they aren't too large, so as to cause drag on the fuselage in flight.

Note: The farther the distance the weight is positioned from the front of the main wing, the less weight is needed for proper balance.
Use this as an advantage for adding less weight and a guide for the positioning of the weight.

Once the weights are positioned, glue them on with decent sized blobs of hot glue to keep them in place.

Step 6: Adding Dihedral

As with any hand glider, this one will need dihedral. If the plane does not have dihedral, it will not be stable in flight. Even if you properly balanced the plane with the right amount of weight, it will still do a nosedive straight to earth if it doesn't have dihedral.
The angle of dihedral for this plane is 20 degrees. In order to apply the dihedral to the main wing, you will have to make some cuts in your wings. And no, your hard work was not in vain, you will not be cutting off the wings. You will simply be scoring them.
In order that you score them in the right place, mark the wing on both sides on the BOTTOM in 2 places 1 inch from the fuselage. Draw a line through the markings over the full chord of the wing. Look at photo 1 for reference.Then cut as shown in photo 2. Now, gently bend the wing up, and hold a protractor up to one side of the wing, as shown in photo 3. The protractor in photo 3 is held at 30 degrees. This is because most hot glues tend to be a bit flexible once dried, so the wing will flop down about 10 degrees due to its weight. Once you have positioned the wing in the right place, put a medium sized string of glue in the cut that you made, all the way down the whole cut. Hold the wing in position as it dries. Repeat the method with the protractor and glueing on the other wing.
The plane is finished! But don't run outside, look at the next step.

(As said above) Any hand glider that you will ever build will need dihedral on the main wing to stabilize it in flight, or it will nosedive.
Here are 2 basic rules: If the plane has wingspan under 30 inches: 1degree for every 1 inch of wing span
If the plane has a wingspan over 30 inches: 0.5 degrees for every 1 inch of wingspan.

Thats it. Now to apply it. Draw two lines on the bottom of the wing, both 1 inch from the fuselage (if the plane has a wingspan under 20 inches, draw the lines half an inch from the fuselage), as shown in photo 1. If you are using cardboard, cut the two layers as shown in photo 1, and bend the wing up. If you are using styrofoam, do the same thing, as most styrofoam is made up of three layers.

Using the angle that you calculated: if the wingspan is over 20 inches, hold the protractor on one side the wing as show in photo 3, so that it measures the angle of the wing when you bend it. Bend the wing so that its angle will be 10 degrees higher than the angle you calculated for the dihedral of the wing. This is because hot glue is still a bit flexible even after it is dry, and the weight of the wing will push down on the glued joint, making the angle of dihedral less. Also, it is much easier to fix a wing with too much dihedral than to fix one with too little. In fact, just to be safe, if the wingspan is over 40 inches, make that 20 degrees higher than the angle you calculated.
If the wingspan is under 20 inches: just hold one side of the wing so that the protractor reads the angle that you calculated, because the weight of the wing shouldn't be significant enough to squish the glue.

As you hold the one side wing in place at the right angle, whether that be 10 or 20 degrees over the angle you calculated, or not over it at all, squeeze a medium sized string of glue (or small, depending on size of wing) into the cut you made so that it fills the cut. Wait till it dries, then repeat the whole process with the protractor and glue for the other wing.

The plane is finished! After all the work, you will finally be able to test it. But, please, look at the next step.

Step 7: Optional Addition and Throwing Technique

All the text, whether it is bold or not, now applies to those who are making this plane or their own.

The optional addition is a launcher that uses a rubber band to launch the plane. It is very simple to make, and requires a simple modification to the fuselage of your plane to function. However it is for smaller gliders only (wingspan 20 inches and under). So, yes you can use it with the plane I made. It is made up of a stick about 6 inches long (find one at the side of your house, make sure it is at least 3/4 inch thick, and cut it to size) with a small slot cut into it an inch from the top. To make one, look at photo 1. To make the modification, look at photo 2. The slot is cut behind the weight, as shown. To make the reinforcement, cut a piece of plastic from a water bottle and glue it in the slot as shown in photo 2. If there is no reinforcement, the rubber band will eventually cut through the cardboard or styrofoam, causing the band to become jammed in the fuselage, making launching with it difficult. Also, the cut the band makes will weaken the nose of the plane. For the correct launching technique, look at photo 3.

Correct Throwing Technique:

Obviously, the larger the glider, the more strength is needed for hand launching. Based on that, do not whip the smaller planes, they will probably hit the ground faster than you can watch it, UNLESS you whip it upwards. But whipping it upwards will just result in a "stall" and the plane either plummeting to earth or gliding gently down. Rather, throw the planes with mild force at a small incline, using a twist of your arm with your elbow at a 90 degree angle. If you don't want to strain your arms from continued throwing, just make the launcher above. For the larger planes with a wingspan of 30 inches and over, throw them with a swing of your whole arm at a small to medium incline.

I am not saying that you don't know how to throw a glider, I am telling you these things because I don't want to be responsible for your broken/damaged planes due to an incorrect throwing technique.

Go outside with your new glider and have fun!