I Pop Pop Boats Lab
Background: The toy was first patented in the late 1800s. It works on some simple physics properties. The candle heats up the small amount of water in the boiler ‘engine’. Water expands when it turns into steam, in fact it can expand 1000x more in volume as steam than its original water volume. If the steam is not allowed to expand in volume, it builds up pressure instead. The expansion of the steam pushes the water out the tube at the back of the boat, and the boat moves forward in the opposite direction of the jet of steam. After expansion, the steam cools and condenses enough to create a partial vacuum, which refills the tube with water, and the cycle begins again. It can eject pulses of water from tubes at the rear just under the water level, at five or more pulses per second. That propels the boat at about 10 cm/s or more, and it should go for as long as the candle burns.
Problems: 1)To successfully make a working pop pop boat. 2) Make the fastest pop pop boat in the class.
Materials:
Engine: Pattern, aluminum beverage can—NO DENTS!, scissors, single edge razor, masking tape , ruler, block of wood or book, waterproof colored markers, i.d. card, 3 Flexible plastic straws (1/4" diameter or 6mm, not too thin), 5 minute quick set epoxy, wooden match sticks, a container that holds water for finding leaks, thin cardboard: cereal box, 10 W hot glue gun, hot glue sticks, thin birthday party candles or tea candles, aluminum foil, stopwatches
Boat Body: Simple: Pattern, thin foam trays that meats or vegetables come in, coins, rubber bands
or 3-D Hull: Pattern, half gallon milk or juice carton, glue, sand paper and stapler.
Deck and Cabin: Pattern, additional milk carton, paper clips, marker, sandpaper, needle nose pliers
Procedure:
1. MAKE WORKING ENGINE. (50 points) Take a rinsed out, clean aluminum can. Pierce the top of the can right above where it curves in with a blade. Insert scissors and cut the top off the can. DO NOT BEND, KINK or FOLD the can while cutting!
2. Cut the can lengthwise, and then continue your cut around the bottom of the can.
3. Cut jagged edges off the can, making the sides as straight and smooth as possible. Do Not cut your hand on the edges of the can!
4. Grab the ends of the aluminum rectangle and put them together. Line up the ends, but offset them a tiny bit. You will see a sliver of silver showing, or the inside of the can.
5. Tape the ends together. Pressing down on the tape ends, push down towards the middle, as you get to the end you will use a ruler or other long item to make a fold with NO KINKS (otherwise you risk the engine not being air tight.) Do not press too hard or it may split open later.
6. Roughly cut out the boiler pattern. Do not cut directly on the lines, but a little outside of the lines.
7. Make 2 tape donuts and attach the pattern to your folded can, one on the tape already on the can, and a second piece on the same side other end.
8. Attached your boiler pattern to the tape, the pattern will hang off the ends of your aluminum. Turn the aluminum over, and cut off both ends of the paper with scissors, but DO NOT cut the aluminum while doing this!
9. Turn back over, and cut exactly on the solid outside lines. Cut slowly and carefully. STAY ON THE LINES. Save one of the metal strips you cut off for later.
10. Write your team or boat name and period on your metal boiler with a sharpie or marker.
11. Find a SHARP edge on a table or door jam. Tape the boiler to the edge, lining up the dashed lines to the sharp edge exactly. The tape keeps the boiler from moving while you fold the edges. Using your fingers and thumbs close to the dotted line, fold over the aluminum on the sharp edge making a 45 degree angle.
12. Peel the boiler off, and turn it around, resetting the tape. Fold over the opposite dashed line on the sharp edge in the same manner as you just did.
13. Peel off the paper pattern and ALL the tape. Be careful to not bend your aluminum while removing the tape.
14. Take a plastic i.d. card and while putting the id card in the folded edge, fold over the edge more, making sure to keep the fold completely straight. Do this on both sides.
15. Take a flat object like a FLAT ruler, block , or book and place it over the fold and push or pound the fold straight down and very flat. DO NOT BEND THE ENGINE in any way.
16. Take the long end of the bendy straw, flatten it slightly with your fingers, and insert it inside of the engine. Repeat this step with an additional straw.
17. Even the tops of the straws and push them into the bottom of the engine, placing your thumb on top of the ends and pushing down. Don’t push too hard or they will come out the end and you will have to start all over. Make sure both bendy parts are outside of the engine.
18. Get a third straw. You will insert this straw, bendy side first. You must insert it on the side with bends folded over. Flatten the end with your fingers to insert it, and push it in to where the bendy part starts. The bend part will be outside of the engine.
19. Cut out a piece of cereal box longer than your engine. Make 2 tape donuts, and attach the tape to the non folded over bendy side. GENTLY press the engine attaching it to the cardboard.
20. Take the piece of scrap metal you cut off earlier. Cut it in half. You will use it to put the quick drying epoxy glue in-between the slits of the folds on your engine to seal it and make it air tight. Practice by sliding the metal piece in-between the folds without glue first.
21. Put a piece of paper down on your desk. Put a piece of scrap cardboard on top. Put SMALL EQUAL amounts of the epoxy glue on the cardboard. Mix the two part epoxy glue with the end of a wooden match stick THROUGHLY. Try not to get the glue on anything, it is a very messy, strong, stinky glue.
22. Using the matchstick, place the glue along the seam of the one of the metal folds. Make sure the glue is along the entire seam. Using the scrap piece of metal, run the metal inside the seam, getting the glue into every possible place in the fold. Pay special attention to get the glue into the very bottom corners, where leaks occur most often.
23. Push glue behind the seam as well. So you are pushing glue into the INSIDE seam and BETWEEN the fold and the engine.
24. Repeat this step on the other side of the engine. Mix more glue as needed and apply.
25. After you have placed the glue inside all the seams, place another thin line to ensure the seal. Set your engine aside for a minimum of 20 minutes.
26. After the glue has harden, take out the straws.
27. Place a ruler at the end of where the bend part begins. Using a marker, mark (39 cm or 1.5 in) on two of the straws. Cut off the ends of the straws at this mark, making the bendy end shorter.
28. Place your ruler at the end of where the bend part begins. Mark 6 mm from the bendy part of both straws.
29. Mix a small amount of epoxy glue. Place glue evenly around the short straw end, AVOIDING the 6 mm area near the bendy part. Do not get glue in this area.
30. Place the short end with the glue into your engine, leaving the 6 mm without the glue, outside of the engine. Do this for both straws. If you get glue on the bendy part of your straw, or push the straw in too far, you will need to start all over! If you get glue on the bendy part, wipe it off with a paper towel before it gets hard.
31. Let this sit for 10 minutes.
32. Carefully remove the engine from the cardboard. Do not bend your engine!
33. Mix a small amount of epoxy glue. You will need to seal all the holes around the straws, at the opening of the engine. There are 4 areas to fill: top of where straws meet, bottom, and left and right of straws. If you have even a pin hole leak, your engine will not work.
34. Place the engine, flat side down, so the glue does not drip into the engine. If you get glue on the bendy part, wipe it off immediately. Let it dry for 10 minutes.
35. If any epoxy gets on the middle of the flat side of the engine wipe it off.
36. FINDING LEAKS. Place your engine under water past the bendy part of the straw. Breath into the end of the straws. If you see bubbles in any areas, you have a leak.
37. Remove the engine, pat dry. Add epoxy glue wherever bubbles were seen. Let dry for 10 minutes.
38. The bendy straws need to be at a precise angle. Roughly cut out the bend pattern. Tape it on to a piece of the cereal box cardboard using tape donuts. Cut out the pattern roughly, then fine cut to the lines.
39. Using the sharp edges of a table, fold on the lines. Remove the tape. Tape together the edges to make a 3 dimensional shape.
40. Pull the bendy part of the straws to their full length. If there is a thin layer of glue on the bendy part it should flake and peel off. Place the engine to the cardboard wedge and have the straws touch on top. Make sure there are no gaps between the wedge and the straws or engine. The wedge should be lined up with the end of the engine. The folded edges of the engine are facing out.
41. When it is lined up right, tape the engine and straws to the cardboard wedge.
42. Using the hot glue gun, you will apply an even layer of glue on the bendy part of the straws, permanently keeping the straws bent at this angle. You will need to get the glue all around the straws. Squeeze out a small amount of glue, then use the tip or a wooden match to spread the glue around evenly.
43. When the glue has cooled and dried, remove from the wedge. (Keep the wedge for later when making the 3-D boat)
44. From the end of the bendy part, measure 102 mm or 4 in. and cut off the shorter ends of the straws.
45. MAKE CANDLE HOLDER. Cut a birthday candle in half. You will have 2 equal size candles. To make wicks on the other piece, pinch or cut away the wax to reveal the wick. The candles need to be small to fit under your engine, if too long, cut to fit.
46. You will need a 5 cm or 2 inch strip of aluminum foil to make the candle holder. Cut the strip in half. You will have (2) 2 x 6 in rectangles of foil.
47. Fold the foil in half, hot dog style. Place a candle about 3 cm from the end. Fold the foil around the candle, rolling the foil around the candle, making a cup.
48. Push the sides of the foil down, revealing the candle more. If the foil is too high, it will extinguish the flame. Write team or boat name on foil.
49. TEST YOUR ENGINE. You need to “PRIME” your engine before every use. Pour water into one straw, and water should come up and out the other straw. Because this is the first time you have used your engine, you will need to do an additional step: Place thumbs over the edges of the straws and shake a few times to get water droplets around the inside of the engine. You will not need to do this step when you use your boat the next time, unless several weeks have passed.
50. With water still primed inside the straws, place the end of the straws into water, with the engine above the water. Hold the bendy part of the straws to achieve this.
51. Light the candle. Hold the candle under the engine, in the middle. If the engine does not start after 30 sec. Shake out the water, re-prime it. You should hear the “pop-pop” that gives the boat it’s name!
52. TROUBLESHOOTING: If your boat still does not work, most likely you have a tiny hole that you did not catch. You will need to put some soap on your hands, get them wet, then put soapy water on the outside of your engine. Blow into the straws, where ever bubbles form, you have a leak. Repair with epoxy and let dry for 10 minutes. Other problems could be a kink in the straw, a bend in the engine, or the bottom pushed or squeezed in by mishandling.
53. Tips: You will need to wipe off the soot with a wet paper towel every once and a while. Throw away the paper immediately so not to stain clothes or tables. Reheat the candle on the bottom to loosen it from the foil, or secure the candle down.
54. MAKE BOAT BODY. You can make a simple foam flat boat (15 points). OR a 3-dimensional boat from a milk or juice carton (25 points).
55. Foam tray boat: Rough cut out the pattern for the simple boat. Make tape donuts and apply to foam tray. Rough cut out the pattern, then fine cut. Using a razor blade is easiest for cutting out the rectangle in the middle but scissors will work. Be VERY CAREFUL when using a razor blade.
56. You will need to add weight to the boat to have the engine push something along. Hot glue 6 pennies to the top of the boat. Put 2 pennies on the back left, 2 pennies on the back right, and 1 penny on each side of the cut-out square.
57. Insert the straws through the hole. Take a rubber band and secure the straws to the bottom of the boat, near the hole, 5 cm from the hole, and a third rubber band from the end of the boat.
58. Make the foil candle holder shorter. Place foil under the rubber band on the end, starting with the candle in the middle of the engine. You can adjust the candle forward or backwards to find the optimum location later.