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Army Raft Design Challenge
As you have researched, in WW2 the Army (what would become the Air Force) stored safety rafts in their planes in case
of emergency landings in the oceans during war. In 1943, Louis Zamperini and his crew’s plane was attacked by Japanese
fighter pilots. The plane went down in the middle of the Pacific Ocean with no land in site. Thankfully the men had a raft
which was easily inflated by the creation of CO2 gas.
You are now given the task to recreate these Army rafts. The winner of this challenge will be the raft that holds the
greatest mass without sinking.
Acetic Acid and Sodium Bicarbonate
The next step of this will be determining how acetic acid and sodium bicarbonate react with each other. You must
determine the ideal amount of acetic acid to react with sodium bicarbonate and create a large enough amount of gas to
cause the raft to inflate and keep as many army men on the raft without sinking. As with any problem, engineers will
face numerous challenges throughout the design process.
Engineering Challenge #1:
You will only be given 25 mL of acetic acid for the reaction to cause the air bag to
deploy. But the sodium bicarbonate amount can be ANY amount, you have to
determine which amount will cause the right amount of reaction to produce the perfect
amount of gas to keep your army men afloat.
Engineering Challenge #2:
Chemicals cost money. Sodium bicarbonate costs approximately 3¢ per gram.
Determine an amount of sodium bicarbonate so that the chemicals for your mock air
bag will be as cheap as possible.
Engineering Challenge #3:
The zip-seal bag (your mock raft) must inflate, but not pop open.
Engineering Challenge #4:
Your mock army raft must be inflated enough so that they float, but also don’t fall off.
Day 1: Raft Design and Construction and First Round of Data Collection and Redesign
Day 2: Second Round of Data Collection
Day 3: Reflection
Day 1: Raft Design and Construction
The basic design of this will be to use a plastic bag and just place the sodium bicarbonate and acetic acid within the bag.
However…..we are engineers here and must expand upon our planning. Are you going to want a multiple bag raft? Yes,
you can do this if you can design a way for the reaction to happen so it benefits the army man. Another engineering
hurdle is cost. You will have a budget of $30.00 for the whole project including the redesign and
all your chemical reaction tests. Side note: this is $30.00 fake money…not real.
Each supply item will be given a
price, this includes your chemicals of sodium bicarbonate and acetic acid. You can only use the supplies provided.
Plastic Bags
Straws
Sodium Bicarbonate
Acetic Acid
Masking Tape
Materials Price List
$3
$2
$.30 per gram
$.50 per 25 mL
$.50 per inch
Initial Design
Budget…how much money do you
have left?
Item and Cost
$30.00
Using the table below test the amounts of sodium bicarbonate (in grams). THESE ARE FACTORED INTO YOUR BUDGET!!!
You don’t get free stuff as an engineer.
Amount of
sodium
bicarbonate
used (grams)
Description of test: How did you test it?
Did you change anything from the
previous test?
Did the acetic
acid react for
this test?
(Yes or No)
Do I need to
add more or
less sodium
bicarbonate?
How did the
raft float?
Based on the data I have gathered, I can conclude that I should use ________ grams of sodium bicarbonate per 25 mL of
acetic acid.
Provide evidence to support your reasoning on why that amount of sodium bicarbonate is the best for raft inflation?
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Day 1: First Round of Data Collection
Now gather data on your raft support the mass of the army men. Start small and work your way up in mass. .
Mass of the Army Men
State of the Raft
Now you have some qualitative data on the effectiveness of your raft. Revisit your original design. Do you need to
change anything? Perhaps the chemical reaction didn’t produced enough energy to create enough gas to inflate
properly….if so what should you change? Did you use more than one bag? Did those other bags fill properly? Think
through this.
** Remember the $30.00 was for the whole project. You may have to reuse some items due to constraints.
Redesign
Day 2: Second Round of Data Collection
It’s the final test. The plane has crashed and we must bring these men to safety!!! How many army men can your raft
can hold.
Mass of the Army Men
State of the Raft
What were some successful aspects of your fellow classmates’ air bags? (Engineers share what went well and what did
not frequently with each other to compare findings and come up with better solutions together)
Pros/Cons of My Air Bag ( My Thoughts)
Pros/Cons of My Air Bag (Others Thoughts)
Day 3: Reflection
Name________________________________________________________________________Date______Block_____
Assessment:
Construct an explanation of how your raft as either successful or unsuccessful using the points below. All points have to
be addressed in the explanation but not in any particular order. You can even address them multiple times in different
ways.
SEP: Design a Solution to a Problem

Max 10 points
Construct a design solution that uses an endothermic or exothermic reaction to solve a
problem (raft)
DCI: Endothermic and Exothermic Reactions


Max 10 points
State the differences between endothermic and exothermic reactions
Describe the flow of energy in endothermic and exothermic reactions
CCC: Energy


Max 10 points
Analyze the flow of energy and cycling of matter in a given system during an
endothermic or exothermic reaction
Describe using evidence the role of energy in endothermic and exothermic reactions and
how it causes change to the surrounding area
Student Reflection/Self Score
Teacher Feedback/ Final Score
Name: ___________________________________________________ Date: _____________ Block: ____________
Army Raft Design Challenge
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