Introduction: Card Stock Trainer Airplane [STEM Plane]
This easy-to-build airplane includes two wing shapes in the plans. Additional wings can be created and subjected to experimental testing. The fuselage design allows wings to be replaced with a bare minimum of effort.
A 1/2" diameter vinyl thread protector (or thread cap) is used to mimic a cowling and protect the nose. It's an inexpensive item that is available at hardware stores. A substitute piece could be fashioned from chipboard.
Other than the nose cap, only card stock and chipboard are needed to make this plane. I use chipboard from food packaging (such as cracker boxes). You can buy 12" x 12" sheets of chipboard at your local arts and crafts store, and that works well. Due to variations of weight, you may need to adjust the center of gravity by sliding the nose cap back or by adding a little clay (or kneaded eraser) in the nose cap to increase the weight.
The CG should be behind the leading edge of the wing, about 33% of the chord length.
-Card stock (65 lb.)
-Chipboard (such as a cracker box)
-1/2" diameter vinyl thread protector
-Utility knife or hobby knife
Step 1: Download and Print
Print or photocopy onto card stock.
Step 2: Cut Out the Pieces
Scissors will be your main tool. The blade and ruler are handy for tight corners.
The fuselage pieces need to be traced onto chipboard and then cut out.
Step 3: Glue Together Main Pieces
The central fuselage piece has the tail fin. Two side pieces are glued it and must line up precisely.
Step 4: Rudder, Elevator, and Wing
The edge of a ruler is handy for this. Use one hand to clamp the card stock to the ruler, and the other hand to gently establish a slight crease. The elevator should be raised by about 10 degrees, and can be adjusted after test flights. The rudder should be straight.
As explained in the directions, there is a fold at the leading edge of the wing. Fold down and under, and use glue (preferably a glue stick) to bond it to the bottom side of the wing, creating a double layer of card stock.
Step 5: Attach the Tailplane
Use a fair amount of glue. Scrape away the excess and allow this to dry for a few minutes before working with it.
Step 6: Establish Undercamber and Dihedral
This is another step that is shown in the video.
You can use the edge of a table or even the edge of a hardbound book to establish some undercamber. Place the wing flat, allowing it overhang the edge by a couple of millimeters. Apply some pressure with thumb or fingers, pushing the leading edge downward a bit. Use very light pressure—do not crease the card stock! Slide the wing so it overhangs by another millimeter or two. Apply pressure again. Repeat this until about 1 centimeter past the leading edge has a bit of curve.
Establish a mild crease for the dihedral angle. Start with a slight angle. Over time, the crease will lose stiffness and the wingtips will want to rise when the plane flies. This can be countered by countered adding a strip of paper or clear tape, about 5 cm long, across the bottom of the wing.
Step 7: Attach the Wing Pull Tabs
These tabs extend forward, past the leading edge of the wing. They help stabilize the dihedral angle and add nose weight.
Use glue and attach the tabs to the centers of the wings. They should taper outward toward the nose. Again, this step is shown in the video.
Two wing shapes are in the plans. If you're going to come up with your own wing designs, try to make them so the median chord is in the same position (relative to the nose of the airplane) as the other wings. This will mean less fiddling with the nose cap to find a good center of gravity.
Step 8: Place Wing and Nose Cap
Once everything has dried for ten minutes or so, you can try sliding one of the wings into the fuselage. If everything was done correctly, it will be held by friction. If the slot is too narrow, use some sand paper to widen it. If it is too wide, can add a layer of card stock to the pull tabs to make them thicker.
If desired, use a marker to shade in a ring on the nose cap, giving it the appearance of an engine cowling on an old radial-engine trainer aircraft.
Slide the cap over the nose. This is the primary source of nose weight, so its position will affect the flights of the plane. With the versions I have made, the CG is correct when the cap is on just far enough to grip.
Step 9: Flights and Adjustments
Sight down the nose and tail of the plane to check for symmetry. Try to resolve any twists or warps, using a light touch.
Conduct some test flights indoors. Throw the plane straight and level, using just a little force. Try to throw it as consistently as possible. Use the elevator to influence the pitch (nose up or nose down), or try sliding the nose cap a little forward or back to change the CG.
Keep in mind that the nose cap will get pushed back by collisions. Make a little pencil mark on the side of the fuselage, once you've found a good position for it, so you can quickly adjust it after a crash.
Use the rudder to influence the plane's yaw. A tad to the left, and it will tend to go left. A tad the the right, and it will go right.
If the plane is wheeling over to the right or left, and crashing nose first into the ground, it is probably tail heavy. If so, the nose cap needs to be further forward, or you may need to just add some nose weight.
CAUTION! Plane may cause eye injury. Be careful when throwing it. If other people are around, allow a safe distance.
1 Person Made This Project!
- Ioannis made it!