2016/02 © Hideo Nakano

nh1886@yahoo.co.jp

A rubber band helicopter

(Toilet paper core propeller version, Feb 2016)

 

Introduction

We have been using assorted materials to make toy propellers since 2005.  If you use plastic bottles, you can make relatively good propellers.  When a PET bottle preform is heated and inflated in the mold, the gravitational force pulls plastic downward and bottle wall near the bottom becomes thicker than the upper part.  Consequently, our plastic toy propellersf two blades have different mass.  We have to paste a small insulation tape strip on the lighter blade to balance the propeller.

Instead of the plastic bottle we started using toilet paper cores to make toy propellers from July 2012.

Ahead of slicing the core, please reinforce the core with diluted PVA glue.  You can make durable toy propellers.  In February 2016, we modified the propeller design again.

 

Take a 4 cm x 14 cm plastic sheet from the bottle.

A toilet paper core propeller (21st Jul 2012)

The latest models

 

Materials and tools

Materials

Tools

A carbonated drink plastic bottle (famous brand),
metal paper clips,
a 5 mm diameter plastic bead,
a toilet paper core propeller template,
a clean toilet paper core,
a 150 mm long and 6.5 - 7.0 mm in diameter strong plastic straw,
160 - 230 g/m2 project paper,
a bamboo toothpick,
a 20 mm x 30 mm thick paper board, and
good rubber bands (approximately 4 cm in diameter soft and durable rubber bands)

PVA glue,
water,
a disposable container,

a big rubbish bag

a pair of scissors (sharp),
a pair of long nose pliers,
a one hole punch
a sharp object (e.g. a needle of compasses),
a 50 cm fishing line, (sticky tape), and

insulation tape (to adjust propeller balance)

 


Preparation

If you want to make good toilet paper core propellers, please dilute PVA glue using same amount of water and mix them well.  Immerse the cores in the diluted glue.  Roll the tube in the diluted glue about 10 - 20 seconds.  You can adjust the tube shapes nicely using a glass bottle shoulder.  After immersing the glue, overturn the tube every 5 minutes until the glue is spread on the core uniformly.  Leave the wet cores for one night to make them dry and strong.

Use disposable containers to immerse the core in the diluted glue.

Paste sticky tape to the four corners of a big plastic sheet and fix it on the floor and place the tubes on it.

 

1. Plastic square with a dish

Collect a famous carbonated drink bottle and using a sharp object make holes in the middle of dish shape hollows.  Then cut out the rectangular shapes like the upper left photo.

Trim the rectangular shape plastics nicely and make plastic squares with the dish shape.

 

2. Axis of the propeller

Using a pair of long nose pliers and a paper clip metal wire, make a shape like 2.1.

Make a small hook with the pair of long nose pliers (2.2).

Pass the straight end of the wire through the plastic square with the dish (2.3 & 2.4).

Pass the straight end of the wire through a 5 mm diameter plastic bead (2.5).

Bend the wire like 2.6.


 

3. Toilet paper core propeller

 

Toilet paper core propeller template

 

Collect clean toilet paper cores or use the reinforced cores (diameter: 40 - 46 mm, height: approx. 100 mm).  Print out the template above and paste it on the core.

 

Cut the cores along the lines on the template and make propeller blades from the core.  You can modify the design to make better propellers.  Make sure that do not forget to open a hole at the centre of the propeller.  Pass the straight end of an axis part through the hole like 3.3 then bend the straight end like 3.4.  Trim the end like 3.5 and fold the end like 3.6 to fix the axis part on the propeller.

An image after the axis was fixed


 

4. Straw (body)

Collect a strong 6.5 - 7.0 mm in diameter plastic straw to make a helicopter body.

Trim the straw to make a 15 cm long straw.

Give two longitudinal 10 mm deep cuts on an end.  The other end must be left intact.

5. Air brake

Make a 30 mm x 140 mm air brake sheet using 160 - 230 g/m2 project paper.

 

6. Rubber band stopper

Cut a bamboo toothpick to make a 15 mm long rubber band stopper.

 

7. Assembly

 

Left images: Make a small rubber band like the upper left image.  Pass the intact end of the straw through the small rubber band about 6 cm deep.  Place the air brake sheet on the straw like the lower left image then put the small paper board with a hole on it.  Stretch the small rubber band over the paper board and hook the rubber band up at the intact end of the straw.

Right image: Pass a 50 cm fishing line through the rubber bands.  (You have to find out the optimum number of the rubber bands.)

Connect the rubber bands with the propeller using the propeller axis hook.

Pass the two ends of the line through the straw from the intact end.

 


Grasp the straw firmly with your left hand then pull the line with your right hand until the rubber bands come out from opposite opening of the straw.

 

Catch the ends of the rubber bands, remove the line and pass the rubber band stopper through the bands.

 

Shift the stopper to the bottom of the cuts at the straw end.

 

 

8. How to make it fly

Do not play with this science toy near any roads.

Hold the straw with you left hand and wind up the rubber bands clockwise through rotating the propeller with your right index finger.  Rotate the propeller at least 50 times.

From the second time, you can give the rubber bands more turns (The maximum number of the turns depends on the quality of your rubber bands.)

Hold the helicopter vertically then release the helicopter into the air.  Do not throw it, just release it.

 

9. Some tips on the toy propeller


If your propeller does not rotate smoothly, you should suspect that one of the blades is heavier than the other.  Please try pasting a small piece of insulation tape on the lighter blade to balance the propeller.

If the propeller cannot give a strong thrust, make the propeller perfectly symmetric like the photo above.  (You can tilt the propeller in the photo to right or left.)

 

10. Please try the followings

1) Remove the air brake sheet and wind up the rubber bands.  Release the straw with the propeller vertically in the air and observe carefully.  You can understand the role of the air brake.

2) Change the size and the position of the air brake sheet.  You can optimize the size and the position.

3) Rotate the propeller anticlockwise (counterclockwise) to wind up the rubber bands.  Then release the helicopter inversely.

4) Change the number of the rubber bands.  (If you use too many rubber bands, the straw might be bent.)

5) Change the length of the straw.

6) In order to avoid injury cases, trim the stopper as short as possible.

 

 

inserted by FC2 system