"HOT LAUNDRY IRON
THERMAL FORMING"
A fun new addition to the water rocket world
developed by Gary Ensmenger
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I just discovered a useful method of using a HOT LAUNDRY IRON to thermalform PETE Plastic.

This new method is the easiest, fastest, and safest methods of creating rounded bullet shaped noses from the bottoms of soda bottles, and also SHRINKING the majority of the entire bottle. Shrinking the bottle gives it thicker wall thickness and a smaller aerodynamic circumference.

LOOK AT THE DIFFERENCE in size between BEFORE (left) AND AFTER (right)!!!

Here's the changes:
(1) Capacity - 2 liter to 1.5 liter (25% shrinkage).
(2) Circmference - 13.625 to 11.875 inches (12.8% shrinkage).
(3) Wall thickness - .0123 to .0142 inches (13% INCREASE)
(4) Height - the new rounded end makes it difficult to determine exactly how much shorter the bottle shrunk, but it appears to be only 3/8 to 1/2 inch shorter.



The trick is to hold some pressure inside the bottle. Here are two examples, (#1) I used a soda bottle cap, drilled it, and epoxied a brass "tank valve", and (#2) a common rubber coated tire valve would work too. The black tire valve works best. With the black rubber tire valve, drill a 35/64 inch hole thru the center of the cap, and press soaped valve thru hole.

I only use a SAFE air pressure of about 10 - 15 psi pressure!! Without holding air pressure inside the bottle while ironing it, it will distort just like the green bottle, (the useless mess pictured at the right).

I set the temperature setting on the laundry iron to HIGHEST SETTING. My iron is rated at 1200 watts.

I also don't stay in the same area very long. Roll the iron on a section once or twice, and move somewhere else.

Note in the movie above that I use a rolling motion of the iron while in contact with the PETE plastic. This is to eliminate scratching of the outside surface of the bottle.

Stay away from the neck and flange. When near completion, you can iron out any wrinkles, and blend surfaces to match. You really have a lot of control of the outcome and how nice the finished product will look.

The rounded bullet shaped nose is achieved by simply pressing and rolling the iron against those five raised areas (feet). Again, don't work on the same area to long, rotate often, and move to the next foot. Eventually they will shrink like shown above. This shaped nose has been called the "GUPPY NOSE". It was first introduced to us and named "GUPPY NOSE" by Clifford Heath. He uses a method of holding the bottle in hot boiling water to achieve this rounded nose.

CREATIVE IRONING

Here are two 20 ounce "SPRITE" soda bottles. I ironed the bottom to a more rounded profile in the left bottle in picture. The ironed bottle has a better profile for traveling through the air. Many times, I've used these smaller bottles for 2nd stage rocket deployment, because they are smaller & lighter.

I ironed a WAIST & rounded the bottom on this 2 liter bottle.



This bottle's body is TAPERED & rounded bottom.



This one is slightly different in shape form the one above.



SHORTY

This one is made from the top and bottom of a 2 liter bottle. I curled the cut edge of the bottom piece to make it strong around the circumference. The top portion and bottom were coated with PL Premium Construction Adhesive, and joined. The top section had some extra overlap and extra circumference. I ironed the cut edge of the top portion & it did a "shrink wrap effect" over the bottom section.

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