Coleman wonder turbine gives 3x the Betz limit!

Thanks to Doug Selsam for this helpful commentary on the Coleman 600W turbine that is only 2 feet in diameter and produces three times the notoriously obsolete “Betz limit“.

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4 Responses to Coleman wonder turbine gives 3x the Betz limit!

  1. Gavin McPherson says:

    I think this is a rebranded version of the Sunforce 600W. The manuals are almost identical and Sunforce are listed for technical support.

    Coleman 600W manual
    http://www.homedepot.com/catalog/pdfImages/6c/6c45f8cc-3aae-497d-899f-609195998b6b.pdf

    Sunforce 600W manual
    http://www.sunforceproducts.com/product_details.php?PRODUCT_ID=187

    The Sunforce 600W rotor diameter is 1.31m (giving a Cp of about 0.4) and the Coleman 600W rotor diameter is quoted as 0.65m (giving a magic Cp of about 1.5).

    It looks like Coleman somehow mistook the turbine radius for its diameter. The blades look about 2 foot long to me – see figures 11&12.

    A purchaser might not be disappointed by the turbine’s output, though they may be a little surprised by its size!

    Gavin

    • admin says:

      Thanks, Gavin, I think you have the answer. Although I am still skeptical even after the performance has been divided by four. Still it is physically possible now.
      hugh

  2. Roger Brown says:

    Hi Hugh –

    How can anything beat the Betz limit though? My understanding Betz is a idealized theoretical max based on blades with zero drag.

    • admin says:

      Sorry, Roger, I was being ironic. I quite often see products being touted on the internet with improbable performance claims and, like you, I respect the known laws of physics and treat such claims with mild hilarity.

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