Origami

Secrets to Make the Best Paper Airplanes You'll Ever Fly

Secrets to Make the Best Paper Airplanes You'll Ever Fly

The "secrets" to making paper airplanes fly well are largely the same adjustments which make hand launched gliders fly well. Most people have the unfortunate idea that a good paper airplane needs no adjustments after the basic folds are finished. All real airplanes have trim tabs to make small adjustments to the plane, and all paper airplanes need small adjustments to fly their best. There are a few basic adjustments and principles which will transform the paper airplane novice into a paper airplane expert. The present article will show you several flying tips for make a paper airplane that fly very well

1 Dihedral
One of the most common paper airplane mistakes is to leave the wings folded down at an angle. That is called "anhedral", and it reduces the lateral stability of your paper airplane. What you want is called "dihedral" which is when the wing tips are the highest part of the wing. The resulting lateral stability will help keep your paper airplane flying straight, or perhaps in a gradual turn. With lateral instability your paper airplane will either roll over on its back and crash, or enter into an ever tightening spiral which becomes a spiraling dive. Just remember - keep your wing tips up.

Technically dihedral provides a stabilizing rolling moment due to sideslip. For example if the plane yaws to the left (positive sideslip), the right wing has a slightly increased angle of attack (AOA) because of the dihedral, while left wing's AOA is decreased (this is most easily imagined if you think about 90 degrees of sideslip). The resulting rolling moment is to the left, which is stabilizing. During a level turn, the yaw rate combined with the stabilizing yawing moment due to yaw rate results in a little bit of sideslip, positive for right turns, negative for left. That small amount of sideslip together with a stabilizing rolling moment due to sideslip (dihedral effect) results in the plane wanting to roll out of the turn. With anhedral, the plane wants to roll into the turn, resulting in a "graveyard spiral". The tendency to roll into or out of a turn is called the spiral mode, which is controlled mainly using dihedral. Most real airplanes have to limit the amount of dihedral they use to keep the Dutch roll mode, a rapid left and right oscillation, under control. While dihedral makes the spiral mode more stable, it reduces the damping of the Dutch roll. I have rarely witnessed any Dutch roll problems with paper airplanes, likely due to increased yaw rate and roll rate damping associated with low airspeeds. As a result all paper airplanes should be flown with plenty of dihedral.

2 Weight Forward is Good
The paper airplane balances is called the Center of Gravity (CG), and there is a specific CG position known as the Neutral Point which provides neutral pitch stability. If the airplane has a CG ahead of this point, the plane is stable, if its behind this point its unstable. Naturally all airplanes without computer assisted flight controls need a CG ahead of their neutral point. For rectangular wings the neutral point is ¼ of the distance from the nose to the tail. For delta wings (such as the common dart paper airplane) the neutral point is ½ of the distance from the nose to the tail.

Stability means the plane, if disturbed, will return to its original state. For pitch stability it means the plane will seek a single airspeed. A plane which is unstable in pitch will either pitch up into a stall, or nose dive, but won't settle out anywhere in between. A stable airplane will tend to oscillate up and down a few times, but converge on a steady flight speed. Many typical paper airplane designs are stable, but just barely. As a plane becomes more and more stable, it wants to fly faster and faster. To counter this tendency, up elevator must be used to produce a good trim airspeed. This is why many of the classic paper airplane designs are nearly neutrally stable. Few people realize good pitch stability requires a heavy nose and some up elevator. The classic designs rely on the small inherent "up elevator" effect (positive zero lift pitching moment) resulting from the swept wing, and possibly the airfoil shape. Thus many classic paper airplanes can be flown with no elevator adjustment. Sometimes they fly well, many times they don't, and they always have poor stability.

I like to add a tiny amount of up elevator to the classic pointed nose paper airplanes, to make sure they don't dive. If I have the time and materials, I like to add a few layers of tape or a paper clip to the nose of the plane to improve its stability. Most "square" paper airplanes have plenty of weight in the nose, and require some up elevator to fly well. Actually the amount of up elevator needed on a paper airplane is a good indicator of its pitch stability. Build a paper airplane (any kind) and place a paper clip on the nose. Make a few flights to determine the best amount of up elevator needed. Now move the paper clip back an inch or two, and repeat. The amount of up elevator needed is reduced, and the plane becomes more sensitive to elevator adjustments. When the paper clip has been moved back to a point where you are using nearly no elevator deflection, and you can't get the plane to fly well, you have the CG at the neutral point (try to balance the plane on a finger, the point where it balances is the neutral point).

3 What about the airfoil shape?
Most people who are reading this know that airplane wings are "Cambered" which means they have generally a curved shape, with the top of the airfoil rounded and the bottom fairly flat. As explained in section 3.0, paper airplane wings must be thin to work well. In addition, they need very little camber, and generally any curvature is limited to the front portion of the wing. I have had people ask me why I don't advocate cambered airfoils for paper airplanes in my books. Since most paper airplanes are flying wings, only small amounts of camber are practical, as large amounts of camber create nose down pitching moments which need tails to balance. Generally I do use a little curvature at the leading edge of the wing. I have noticed that paper airplane performance is not noticeably degraded with flat, uncambered airfoils. The reason for this is likely due to low Reynolds numbers. Remember that a large portion of the boundary layer across the front of the wing is laminar flow, but for high lift we need a turbulent boundary layer. The use of a flat uncambered wing produces a large pressure gradient at the leading edge, which likely aids the transition to a turbulent boundary layer, which could likely be the reason for little camber in insect wings. Also, swept wings with uncambered leading edges promote vortex flow just behind the leading edge on the upper surface. Although lift coefficients at these Reynolds numbers aren't large enough to promote a large amount of vortex lift(vortex lift increases exponentially with lift coefficient), any vortex flow likely helps the transition to a turbulent boundary layer.

Paper Airplane. Excellent Games To Entertain Inside Home

Many of the paper airplanes flying you do will be inside home, at home. Indoor flying has some major advantages - no wind to carry off your plane or send it crashing to the ground. No precipitation to change it into a soggy wreck. No sunlight to get in your eyes. No trees or bushes to swallow down your airplane in the branches. And Inside Home game is great for paper airplane contests because it balances everyone flies under the equal considerations. (For more on paper airplane contests, see my web page origami-kids.com) But indoor flying also has a few problems, namely walls and ceilings, not to mention furniture, to crash into. The thing to do is to turn these drawbacks into benefits. Here are some games you can play that take advantage of the fact that you´re inside

 

Paper Plane Golf
This game is a lot like the real game of golf, but you play it indoors using your arm and a paper airplane rather than outside using gold clubs and a ball, and it doesn´t take nearly as long. You can play the game alone or with friends. We recommend using the Count, Slice, or Butterfly. Choose between three and nine landing spots (these will be your ´holes´), such as chairs, tables, and small rugs. They don´t all have to be within one throw of each other; in fact they don´t even have to be I the same room. In golf it´s normal to have to hit a few shots between holes, and in this game you can set it up so that some holes require at least three to five throws. If you want, number the ´holes´ with pieces of paper so you remember the order you´re supposed to go in. the object of the game is to land on all the spots using the fewest number of throws. If you set up a challenging and fun course, write down where all the holes are so you can play the course again and improve your ´golf´ game. This is an excellent game to play if you´re sick and have to stay in bed. It´s also fun if you´re sick and have to stay in bet. It´s also fun if you´re feeling lazy or watching TV. All you need is a paper airplane (almost any kind will do), about 15 feet of string or strong thread, and some tape. Tape the string to the pane near where you´d hold it to throw it. Then tie the other end of the string to your wrist. Choose or set up a target about 10 feet away from where you are and see how well you can land on it.

Catching A Plane
You´ll need two or more people and at least one airplane for this game. Any model will do, but we recommend the Butterfly, Slice, or Count. Start by standing close together, and then have each player take two big steps away from the others. Throw the plane back and forth as if it were a ball, with the players plucking it from the air. Try to grab the plane by the fuselage so it doesn´t get squished. After you´ve successfully thrown and caught the plane a few times, each player should take another between you is too great, or you bump into a wall or piece of furniture. Variation: once you get good at the game; try using as many planes as there are players so that everybody is throwing and catching at the same time.

Wedding Arts and Crafts Ideas For Kids

Wedding Arts and Crafts Ideas For Kids Weddings can bring out the kid in all of us as we plan and dream and decorate. When you're planning a wedding kids will have a part in, you might want to involve them with some wedding-themed arts and crafts. Here's a list to get you started: 1. Cutting and folding: * Origami: kids of all ages and skill levels can enjoy making folded paper objects. Origami of all kinds produces elegant products that you may even want to display or give as favors at the wedding. Consider boxes, swans, and cranes.
* Snowflakes and confetti: bring the kids into the decorating by allowing them to cut snowflakes for a winter wedding or colored confetti for invitation envelopes. * Paper dolls and chains: paper doll or decorative chains can make unique decorations for the wedding or a fun craft for the kids to do at the reception. 2. All that glitters * Wire wrap and jewelry: let the kids make wire-wrap sculptures, mobiles, or jewelry with thin jeweler's wire in silver, bronze, or jewel tones. Beads: let the kids help with favors by giving them beads and wire or string. They can make necklaces, keychains, rings, and bracelets with glass or metal beads. 3. Flowers * Clay roses: Sculpey or other craft clay comes in a wide range of colors and can be rolled out into flower petals and stems. * Potpourri: dried flower petals can be combined in bowls or sachets for decorations or wedding favors. * Marzipan: similar to clay flowers, marzipan can be rolled and sculpted into intricate flower designs. But these flowers are edible and delicious! * Flower press: make small flower presses out of cardboard, wax paper, and wingnuts and bolts and give them to children at the wedding. They can use them to press some of the wedding flowers and keep them as keepsakes or give them to the bridal couple as gifts. 4. Fun with words and cards: * Calligraphy: let older kids be a part of the wedding planning by teaching them the art of calligraphy. They can help address the invitations and thank you cards and put together fancy boxes and gifts for wedding favors. More invitation fun can be had with glitter, confetti, and rubber stamps and ink. 5. Butcher paper and markers * Make a card for the wedding couple: at a casual or intimate wedding, or one where many children will be present, you might want to lay out long strips of butcher paper or find giant greeting cards for the kids to decorate with markers. Adults can leave messages and well-wishes for the bridal couple's future. Kids can be brought into the wedding planning and execution in many ways. They can be flower girls and ring-bearers, of course, but they can also help in the creation and layout of decorations, in assisting guests to their seats in the wedding or reception, and can even be a part of the receiving line. Integrating children into the ceremony and reception can be a way to help make children in blended families feel like an integral part of the new family. At large family weddings, having activities for the children can help keep them occupied and happy, which allows the adults to fully enjoy the wedding, as well.