Friday, December 5, 2014

Stumped by STEM

MSR Wisperlite and STEM

Nothing is more humbling than trying to create a STEM lesson plan for 11 year old boys. My History degree reflects my appetite for consuming information, making logical connections, presenting a hypothesis followed by supporting arguments. So building a STEM lesson into a process is fine. But some of the science still escapes me.

My Audience has the Attention Span of an 11 Year Old

My son is part of Troop 404. I want to be a good Dad, and provide some input to their scouting skills with the ulterior motive of forcing a bit of STEM into the process. We covered the use of Cotton Balls and Vaseline as tinder to start a fire. 11 year-olds are fascinated by fire.
State Changes: Solid, Liquid, Gas
We never really reached deep into the science of the flint and steel - a standard tool for scouts. Some metals burn (oxidize) at room temperature. Scrapping minute balls of metal from the flint exposes more of their surface area to oxygen - which causes them to burn. That's the trick.

We did start the discussion of the state change of Vaseline from solid, to liquid to gas as it was wicked by the cotton then burned. But you know... 11 years old.

Science: Change of State, Wicking, Oxidation,
Technology: Various tools to create fire/sparks
Engineering: A one-handed steel and flint (engineering simplicity)
Math: How to calculate the optimum amount of Vaseline (fuel) for a cotton ball (wicking framework) for maximum burn time.

From Flaming Cotton Balls to the Wisperlite Stove

The Wisperlite stove has not changed much in 30 years. I can say this definitively because I own the 30 year old version. These stoves consume, burn, various types of liquid fuel. But something else is happening as the liquid fuel moves from the canister, through the stove and into the burner.  

In the video above - did you notice that the correct way to start this stove is to set it on fire? A few drops of fuel in the lower cup, a source of fire, ignites a big yellow flame, then it burns down into an intense blue flame that sounds like a miniature jet engine. It's not like lighting your stove, or a BBQ grill.

You Can't Skip Steps to Get to the Jet Engine.

Something Else is Happening

I sent an email to MSR to ask if they have a simple description of the process. Is it a wicking effect like the candle example above, or a venturi effect, or flash evaporation? Or, is it some combination of these processes?
Proof that Math is Hard.
You have seen flash evaporation...
but does this explain the Wisperlite?


I hope MSR will reply, so I can build out:
  • Purpose and Materials
  • Course Goals / Instruction Mode
  • Student Goals
  • Syllabus
  • Content / Arranged
  • Supplemental Materials / Activities
Next up: Tent Technology, Thermarest, Scope Reticles.

The graphics above are linked to their original sources on the web.

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