Introduction: Soda Bottle Rocket Launcher($13.97) a Child's Smile(PRICELESS!)

Picture of Soda Bottle Rocket Launcher($13.97) a Child's Smile(PRICELESS!)

YES, another great STEM activity with a new twist to the “egg-drop”…

Students are tasked to design and construct a soda bottle H2O rocket, successfully launch with its (egg) payload and recover unbroken (See Step 14 - Design Brief).

We spend time initially discussing the "design process". There are many versions, but the majorities have several steps in common: problem statement; defining criteria; research; brain-storming; modeling; testing; improvements; manufacture...

Many valuable lessons that can be incorporated into unit, i.e. Newton's Laws of Motion, Trigonometry, English-to-Metric Conversion, Statistics.

Concepts covered:
Engineers develop models to evaluate possible solutions.
Knowledge gained in other disciplines impact development of products & systems.

Lessons Learned:
Research & development are problem-solving techniques widely used in the business world & technology.

Application:
Students will apply research and the design process to solve problems in and beyond the classroom...


 

Step 1: Constructing Launch Pad

Picture of Constructing Launch Pad

To level the “playing field”, I constructed the launch pad… the materials you’ll require, with the exception of the tire valve, can be found at building supply or hardware stores.

10 feet - 1/2" PVC Pipe Schedule 40(DON’T CONFUSE WITH CPVC) 

(1)  2” Long Piece, 1-1/2” PVC Pipe Schedule 40  

(4) 1/2” Slip End Caps

(2) 1/2” Slip Tees

(1) 1/2" Tee, Slip & Internal Thread

(1) 1/2" Adapter, Slip & External Thread

NOTE: THE INTERNAL & EXTERNAL THREADED PARTS ALLOW DISASSEMBLING FOR EASY STORAGE.

(1) Small Can PVC Cement

(1) Small Can  PVC Cleaner

(2) Hose Clamps w/at least 2” Diameter

(9) Multi-Purpose/Zip-Ties, minimum 8” Long                                                             

(1) Small Roll Duct Tape

(1) Small Roll Teflon Tape

(1) Small Roll of 2” Painter or Masking Tape

(1) Tire Valve/Stem – Local Automotive Supply Store

15 feet Twine or Thin Rope

(2) 2-Liter Soda Bottles

 

TOOLS:

Tape Measure & Pencil

Hand Saw (Hack-saw, Back-Saw, or X-Cut)

Portable Drill

1/2", 3/16” & 1/4" Twist Drill Bits

Pliers

Heat Gun or Candle

Scissors or X-Acto Knife

Air Pump w/Pressure Gauge or Air Compressor

Step 2: Let's Begin...

Picture of Let's Begin...

CUT THE PIPE, six pieces, 12 inches long; one piece, 24 inches long; and one, 8 inches long of 1/2” PVC.

DRILL HOLE FOR TIRE VALVE, place an end cap on a piece of scrap wood, holding securely with pliers, first drill 1/4" pilot hole and then 1/2” hole in the top

INSERT THE VALVE, slide the valve through the hole in the end cap; grab the end of the valve cap with pliers and pull until fully seated.

Step 3: Glue & Assemble Base

Picture of Glue & Assemble Base

GLUE & ASSEMBLE THE BASE, lay-out the pieces in the order in which they will be assembled: end cap, 12-inch section, slip tee, 12-inch sections, end cap, etc.

Clean the outside of the pipe and inside of the fitting with PVC pipe cleaner. Glue the pieces one at a time, cement sets in seconds…

Attach the 8” piece of PVC to the base with a pipe clamp to act as a string guide.    

Step 4: Creating Bottle Seal

Picture of Creating Bottle Seal

CREATE BOTTLE SEAL, this bulge will create a seal between the pipe and the soda bottle. Mark the vertical piece 10-inches from the open end. Using a candle or heat-gun, heat the pipe evenly at this mark until it becomes soft. Grasp pipe on either side of mark and push together to create a slight bulge. Hold the pipe straight until cool and no longer soft.

Step 5: Bottle Clamp

Picture of Bottle Clamp

BOTTLE CLAMP; holds bottle tight to bulge. Tape nine (9) zip-ties together with duct tape, making sure the ties all face the same direction, are parallel and their heads line up evenly. Tape both sides to hold securely.

Slide a soda bottle over the end of the pipe until it seats against the bulge. Wrap the zip-ties around the pipe with the heads facing inward, catching the lip of the bottle. Secure the zip-ties  with a hose clamp. 

Step 6: Launch Trigger

Picture of Launch Trigger

LAUNCH TRIGGER; cut the top and bottom off a 2-liter soda bottle with a pair of scissors. Flatten the middle section using care not to crease it, held with painter’s tape, cut a 1-1/4 inch hole through both sides. This will hold the trigger in position until you’re ready to launch.

Drill a 3/16” in the side of a 3-inch piece of 1-1/2 inch PVC pipe. Tie piece of 10-foot string through the hole.

Step 7: Assemble Trigger Mechanism

Picture of Assemble Trigger Mechanism

ASSEMBLE TRIGGER MECHANISM; slide the “trigger spring” over the end of the pipe, the zip-ties and snuggly against the pipe clamp. Next, slide the “trigger” over the pipe and zip-ties. Thread the string through the holes in the “spring” and the “guide”. Conduct a test; the “spring” should hold the “trigger” up and over the ties…it should drop, allowing the ties to open up when you pull the string.

Step 8: Launch Sequence!

LAUNCH SEQUENCE! Fill the soda bottle about one-third full of water and slide onto the end of the pipe until it’s seated against the bulge. Slip the ties over the bottle’s lip and slide the trigger up over the ties.

Pressurize the launcher with either a bicycle pump or air compressor. Exercise caution not to exceed 70 psi…

3-2-1… PULL THE STRING!!!

Step 9: Trouble-Shooting


Rocket does not launch:

1. Vertical piece of PVC pipe may need to be sanded a little so that mouth of bottle slids on/off easily. Caution not to sand down seal too much...

2. As you charge launcher, water/air escaping...loosen pipe clamp, seat bottle neck against seal, reposition zip-ties, re-tighten clamp.





Step 10: Safety Precautions


Respect as you would a loaded firearm...

Recommend 70 psi...not to exceed 90...worse case scenario, rocket could explode w/a loud"BANG", possibly causing ear damage.

Launch in a large open area away from parked cars and populated areas. Designate stand-off distance of 25 feet from launcher.

Restrict payloads...no rocks!

Adult(s) only charge system. Wear eye & hearing protection. Have your back towards launcher as charging.

These are by no means all inclusive...list will grow w/experience.

Step 11: Calculating Rocket's Altitude

Picture of Calculating Rocket's Altitude

 

We calculated rockets elevation with a home-made elevation tracker for less than $.50 cents or you can purchase a commercial one at most hobby/model stores for $20...

Ours was constructed with a meter stick, protractor, some string and a weight (flat washer).

The tracker is designed to measure the angle a rocket reaches from a known distance from the launch pad and a mathematical formula. Note: More accurate if the angle is below 45 degrees.

(Tangent of Angle) X (Distance from the Launch Pad) = Rocket Altitude

I use two (2) students, a “tracker”, whose responsibility is to track the rocket from launch to the highest point of flight (apogee) and determine the angle. A “recorder”, who calculates and records the data, both are positioned 300 feet from the launch pad and at right angle to wind.  

For ease, we use a table with values of the tangent for various values of angle (See Step 12 – Table of Tangent Angle).

Example: If you are 300 feet away from the pad, and measure an angle of 27 degrees, the tangent of 27 = .5       

.5 X 300 = 150 feet altitude

Step 12: Table of TAN(Angle)

 Table of Angles and Their Tangents
Angle Tangent ° ° Angle Tangent ° ° Angle Tangent
0 0.0000 30 0.5773 60 1.7317
1 0.0175 31 0.6008 61 1.8037
2 0.0349 32 0.6248 62 1.8804
3 0.0524 33 0.6493 63 1.9622
4 0.0699 34 0.6744 64 2.0499
5 0.0875 35 0.7001 65 2.1440
6 0.1051 36 0.7265 66 2.2455
7 0.1228 37 0.7535 67 2.3553
8 0.1405 38 0.7812 68 2.4745
9 0.1584 39 0.8097 69 2.6044
10 0.1763 40 0.8390 70 2.7467
11 0.1944 41 0.8692 71 2.9033
12 0.2125 42 0.9003 72 3.0767
13 0.2309 43 0.9324 73 3.2698
14 0.2493 44 0.9656 74 3.4862
15 0.2679 45 1.0000 75 3.7306
16 0.2867 46 1.0354 76 4.0091
17 0.3057 47 1.0722 77 4.3295
18 0.3249 48 1.1105 78 4.7023
19 0.3443 49 1.1502 79 5.1418
20 0.3639 50 1.1916 80 5.6679
21 0.3838 51 1.2347 81 6.3095
22 0.4040 52 1.2798 82 7.1099
23 0.4244 53 1.3269 83 8.1372
24 0.4452 54 1.3762 84 9.5045
25 0.4663 55 1.4279 85 11.4157
26 0.4877 56 1.4823 86 14.2780
27 0.5095 57 1.5396 87 19.0404
28 0.5317 58 1.6001 88 28.5437
29 0.5543 59 1.6640 89 56.9168

Step 13: Rocket Data Sheet

       
Student's NameAngleTangentAltitude
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
 
 
   
       
Mean=the sum of the values of data set, divided by number of values in a data set.   Mode= most frequently occurring value in a data set
Median= value that occurs in middle of data set arranged in chronological order.  NOTE: Data set w/odd# of values always has median…for even# of values, two middle values are averaged w/results being the median
Range= difference between the largest & smallest values that occur in a data set

Step 14: Design Brief

 

 Client:                                 US based school supply store chain

 

Target Consumer:            Educators, youth groups, clubs, & home-schooled, etc.

 

Problem Statement:          Proven fact that America’s youth are falling further and further behind other countries in areas of science, technology, engineering and mathematics. To further compound matters, national, state and local governments are facing deeper and deeper budget cuts each year. How can we help classroom teacher meet these challenges and still offer a quality education with dwindling resources?

 

Design Statement:            Develop a “turn-key” unit on rocket propulsion. Content as minimum should include topics: Newton’s 3 Laws, calculating rate & height of assent, design process. Able to achieve same comparable results of more expensive “kits” yet at a portion of the costs. Content covers topics taught in other disciplines. Materials consist of common house-hold items or off-the-shelf at local retailers.

 

Constraints:

1.    2-Liter soda bottle

2.    Achieve minimum height of 20 feet

3.    Successfully launch and recover payload (egg)

4.    Gross Rocket Weight (GRW) 160 grams or less.

5.    Inexpensive, utilize common house-hold items

 

 

 

 

Step 15: Rocket Rubric

CATEGORIES54321
DesignSimple, Clean, excellent choice of materialsSimple, Clean; minor changes while constructingComplex, major changes to original designToo Complex; materials incompatibleIncomplete
ConstructionGRW less than 160gGRW less than or equal 170 gramsGRW less than or equal 180 gramsGRW less than or equal 190 gramsFails to Complete on schedule
LaunchingZero Structural FailuresMinor Structural Failure; launch unaffectedMinor Structural Failure; affects launch & altitudeMajor Structural Failure; barely manages to launchFails to Launch
Height50 Feet (+)40 Feet (+)30 Feet (+)Grter/Equal 20 feetLess Than 20 Feet
Recovery System FunctionFunctions as designedMinor malfunction; no impact on payloadMajor malfunction; significant impactMajor malfunction; extensive damage to payload System failure
PayloadNo damageSuperficial cracks; contents undamagedClearly visible cracks; contents seepingShell broken; contents leakingShell destroyed; contents unrecoverable

Comments

Felreaver (author)2012-03-08

This is by far the coolest project in my opinion thank you very much for such a wonderful idea.

desperado dave (author)Felreaver2012-03-08

thanks...have fun! A lot of fun on hot summer day...

wilgubeast (author)2012-02-27

That is awesome. Thanks for including rubrics and a picture of such an enthusiastic rocket scientist.

You're welcome...RS is our grandson, Ethan!

joen (author)2012-02-26

Oh yes does it ever! Some how I had it turned around so that the trigger spring was slid from the bottom up. Obviously that won't work. You said it quite plainly. It just didn't sink in. Makes sense now.

Thanks for the clarification.

Joen

joen (author)2012-02-26

Hello,

Sorry but the coffee isn't stimulating the few brain cells that are left so I don't understand the need and function of the "trigger spring". Is it the middle part of a 2 liter bottle with the two holes cut in it? How exactly does it attach to the launcher and trigger and what exactly does it do?

Those answers may be clear to everyone else but I am stumped.

desperado dave (author)joen2012-02-26

No problem Joen...the spring rests on the hose clamp that holds the zip-ties, underneath the 2-1/2 inch piece of PVC (trigger). Its purpose is to hold the "trigger" in place until you pull the string...otherwise the trigger will slide down, releasing the zip-ties. If not for the spring, you'd have to physically hold the "trigger" up and around the zip-ties. Hope that helps...

DD

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Bio: Semi-retired...currently teach woodworking, sheet metal & CAD. Enjoy all outdoor activities...passion is x-c and alpine skiing.
More by desperado dave:No Batteries Required...Hand Tools OnlySoda Bottle Rocket Launcher($13.97) A Child's Smile(PRICELESS!)Survival Kit - STEM Project
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