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Helicopters Building Design Portfolio Don R (Science Olympiad)

New event in Division B, I'm trying to understand the basis, and put together a presentation.

Don R

on 18 October 2012

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Transcript of Helicopters Building Design Portfolio Don R (Science Olympiad)

Helicopters Building Design Portfolio Science Olympiad Don R. How a Science Olympiad Helicopter Flies

When built properly (which you will find out how to build one in this presentation), there are two basic things that you have to do to make it fly. Basically twist the top two rotors (might look like wings) about 50 times around or so, or until the motor (rubber band) is over-twisting. (See diagram 1), and then release. As simple as that. Materials needed to build a Helicopter
Thin balsa wood (can buy in a helicopter kit, or get it at a hobby shop and cut your own shapes).
Balsa rotor blade edges and ribs
Balsa rotor
Metal Hook
Rubber Band
The Rotor is known as pretty much the propellers or blades of the helicopter. To be more specific, I usually call the propeller part "rotor blades" or "blades". The rotor is probably the most important part on the whole helicopter, since it is used for flying. Rotor Blades
The Rotor Blades are the two propellers at either end of the helicopter. These attach from the ends of the body, and are the second most important part in flight. Their structure is made out of balsa, with 3-5 smaller pieces (ribs) attaching on each side of the wing to hold it together. It is filled with a filament similar to saran-wrap, but thinner. Each side of the blade should be at a slightly different pitch. Motor Frame (body) Rotor Blades Rotor Blades Ribs Ribs (More description)
The ribs are important for the structure of the helicopter. They hold the edges of the blades together, and position the filament. Without them, the blades have more of a chance to break, an the filament would be useless. Blade foil
The blade foil is the saran-wrap type foil (as described before) that goes in the middle of the blades, but overlaps the ribs. This wrap stops the helicopter from catching the air and going much slower. This would be due to the pores in the blade that allow the air to pass through without pushing it away. Assume this next diagram of a wing is filled with filament. Air pushing down or forward (blue) Air against the surface of filament (yellow) In the diagram, the air gets pushed outward towards the edges of the blade and curves off. This is how the helicopter pushes through the air. Now in the next diagram, assume the wing contains no filament. Air pushing through the blade (blue) Air passed through. Going to the sides (yellow), going down or forward (red). In this diagram, the air is allowed to pass through the blade, due to the pores with no filament. This air slows down the helicopter, and may make it fail. It is strongly recommended. Motor + Motor Hooks
The Motor is in the body of the helicopter and is almost always a rubber band. It is held on by two motor hooks (one at each end) and a small frame containing two balsa sticks or tubes, and two balsa caps. The motor is what makes the helicopter fly. Motor Hook (Spinning) Motor Frame Motor Hook (Stationary) Notice how the two motor hooks are labeled "spinning" and "stationary." When you fly a helicopter, you twist the top rotor blades, therefore twisting the the "spinning" hook and then the rubber band. The bottom hook remains "stationary." Part 2 - Materials, Advantages, and Disadvantages Balsa Wood
Used for Motor Frame, Motor Blade Outline, Ribs, and a disc on the top.
Advantages: One of the lightest woods on the planet, some types of balsa weigh less than a gram per cubic centimeter. When built into a structure with many bars of support (ex: towers last year), can hold a number of pounds.
Disadvantages: Weak when unsupported, bendable, extremely easy to crack, not recommended for anything other than a simple project or event (like helicopters). (Reminder) Materials needed to build a Helicopter
Thin balsa wood (can buy in a helicopter kit, or get it at a hobby shop and cut your own shapes).
Balsa rotor blade edges and ribs
Balsa rotor
Metal Hook
Rubber Band
Filament for Blades Metal Hooks
Used to hold the motor
Advantages: Hard, not very easy to break, allows the motor to be removed and replaced, and the hook stays in its place (unless someone bends it).
Disadvantages: Adds lots of weight (recommended to use lighter metal like paper-clip type), but don't get too light, the metal will become flimsy and easily breakable. Motor (Rubber Band)
A rubber band hooks on by the two metal hooks and used as the motor.
Advantages: Easily powered (twisted) and replaceable, doesn't add much weight, allows helicopter to fly smoothly (if built properly and rubber band twisted properly).
Disadvantages: Breakable (especially when twisted improperly), may make the helicopter fault if it wasn't built properly, twisting too many times could cause a stall in flight. Tape/Glue
Used for attaching different parts of the helicopter together.
Advantages: Good glue > (insta-cure cyanoacrylate recommended), is a thin liquid glue that weighs hardly anything, dries instantly, and can hold the balsa wood together VERY well.
Disadvantages: Pretty much any tape, Elmers glue, paste type glue, hot glue, and other heavy glues. Also, the insta-cure should only be used for balsa, make sure to get a stronger but not too heavy glue. Blade Filament
Used to close air passageways in the blades so the helicopter will fly faster without as much air pushing on it.
Advantages: Light, strong, removable, closes air passageways for better flight.
Disadvantages: Could flap around if not tight enough, easily damaged if tampered with, could easily fall off during flight if it isn't put on correctly. Part 3 - Design Plan I will be showing you each step it takes to build a small balsa, rubber-band motorized helicopter. Each step I will have a diagram with arrows pointing to different parts of the helicopter and an explanation of how to build and complete each step. Assembly of a small balsa helicopter Step 1 - Assembly of the motor frame
Begin by taking two 1/8 * 1/8 * 10 inch pieces of balsa stick and place them approximately one inch apart (3/4 inch space in the middle). Specific Materials Necessary for Building (buy at a hobby shop)
2 long thin pieces of balsa that measure 1/8*1/8*10 inches
Insta-cure cyan. glue (recommended)
Two strong pieces of balsa that measure 1*1/2*1/8 inches
Two 1/8*1/8*4 inch pieces of balsa
One small motor hook about 1-2 inches long
One small motor hook that has a part in the middle that still allows the hook to spin when its glued down
One small balsa circle just a little bigger than a dime
Plastic film (similar to saran-wrap but thinner)
Two long thin pieces of strong balsa that measure 1/16*1/16*50 inches (if possible, should total to about 100 in.
One long rubber band (at least 6 inches)
Small razor blade Step 2
Glue the strong 1*1/2*1/8 inch balsa pieces to the tops of each motor frame edge (both 1/8 inch sides should be glued together, making the frame flat). Step 3 - Rotor Blades
Take both long 1/16*1/16*50 inch long piece of balsa and cut (with a small razor blade), eight 2-inch pieces, and eight 5-inch pieces. These will serve as the edges of the blades. Step 4 - Edges of the Blades
Take two 5-inch and two 2-inch pieces of balsa (from step 3), and glue them in a rectangle shape (shown in diagram), after you're done, repeat this step three more times with the other wood. Step 5
Take the remaining 1/16*1/16 balsa and cut twelve 2-inch pieces. These will be the ribs. Every 1¼ inches on the blade, glue one on. There should be three glued, and they should overlap the edges of the blade. Remember to get them straight. Once you are done, repeat this with the other blades. Step 6
Take one 1/8*1/8*4 inch piece of balsa and lay it flat in front of you. Take one blade and glue its lower right corner onto the left side of the 4-inch piece. They should overlap about one inch. On the other side of the 4-inch piece, sand the rightmost inch at about a 45 degree angle (optional), then, take the other blade, and glue the top left inch to the sanded inch. If you didn't sand, simply take the top left corner to the rightmost inch on the piece. When you are done, do this with the other two blades. Step 7A - Attaching motor hooks
Your motor hook should have some device on it that allows it to spin when glued, or I can't explain how to attach it. (some idea of what it should look like in picture, ignore the gold nut, I tried to put a good picture together. Also, the actual hook should be MUCH smaller than this). If you don't want to find one, then use two stationary hooks. This hook is your spinning hook. Step 7B
To attach the motor hooks, glue the part of the hook that best resembles the gold nut in the diagram (it is probably plastic), onto one of the 1*1/2*1/8 inch balsa pieces, bottom of the piece meeting the bottom of the special piece. Step 8
Attach the motor hook to the blades by gluing the piece that is bent at the end, and curl it over to glue to blades. This should be glued in the direct center of the middle 4-inch piece. Step 9
Now take the other hook and glue it to the opposite end of the motor frame, on the other 1*1/2*1/8 inch piece. This hook should not have the special piece in the middle, but nothing. Glue the bent piece at the end the same way as you did before, but with the other set of blades. Here is what it should look like (about) finished. Step 10 - Filament and Motor and balsa circle
Take a large sheet of the saran-wrap type filament or whatever else you are using, stretch it until it is taut, and cut four 5 by 2 inch rectangles out (size of blade). Glue the sheets of filament on the side of the blade that you glued the ribs on. Then, take the rubber band and make sure it fits between the two hooks, and is a little taut. Lastly, glue the balsa circle to the top of the helicopter, right on top of the spinning hooks' attachment to the blades. (Science Olympiad requirement only) Part 4 - Test Plan There are just a few simple steps to test this model of the helicopter Step 1
Make sure there are no loose or wobbly pieces on any part of the helicopter. Step 2
Make sure the top blades twist the spinning hook, which allows the rubber band to twist. Twist the rubber band about 30-50 times or so, but not too much (next picture) Good Twist Bad Twist Tip: The motor has to be removable, so DON'T glue it on to the hooks! Step 3
After you have twisted it, release, and let it FLY! If it doesn't take flight, consider checking the placement of the hooks and the number of twists in the rubber band. Thanks for Watching!!! (Bibliography on next slide) Bibliography
North Carolina Science Olympiad website - http://www.sciencenc.com/event-help/eventphotos/helicopters_picture_page.php
Google images
Wikipedia - http://www.wikipedia.org
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