{"id":3750,"date":"2011-07-18T09:56:56","date_gmt":"2011-07-18T16:56:56","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=3750"},"modified":"2011-07-18T14:11:29","modified_gmt":"2011-07-18T21:11:29","slug":"a-useful-spreadsheet-and-gfc-handicapping-tool","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/a-useful-spreadsheet-and-gfc-handicapping-tool\/","title":{"rendered":"A Useful Spreadsheet and GFC Handicapping Tool"},"content":{"rendered":"

For\u00a0analyzing the greatest economy from an aircraft\u2019s design, Howard Handelman, a highly-engaged reader of this blog, provides a link to his web site, which includes a downloadable spreadsheet he has devised that will give the inquiring reader hours of enjoyment.<\/p>\n

Handelman, self-described as, \u201cjust a retired IT guy,\u201d with \u201cweak math skills,\u201d but a \u201ccompulsively curious\u201d nature, has devised a tool for analyzing any airplane\u2019s performance <\/a>based on a few known variables, and which he has applied to many of the Green Flight Challenge\u2019s aircraft.<\/p>\n

The basis for his analyses is his \u201ctriangle tool,\u201d a wedge that can be used to help design propellers, \u201ctest [the] truth\u201d of claimed aircraft performance, and estimate brake horsepower in real life circumstances (at least within the parameters of the triangle tool).\u00a0 Handelman notes that some aircraft, including those with laminar flow, will “not fit the model\u00a0very well because they don’t fit the V-squared curve.\u00a0 Synergy won’t look anything like the model.”<\/p>\n

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The simple triangle - basis for Handelman's analysis<\/p><\/div>\n

His findings are bound to be controversial, and certainly provide a basis for an ongoing discussion.\u00a0 Based on an analysis of several GFC challengers \u2013 individually evaluated on his site, Handelman reaches several conclusions he will elucidate in his presentation at Oshkosh’s AirVenture 2011.<\/p>\n

Greenelis, for instance, may reach the GFC minimums, but its numbers conflict \u2013 and he thinks it is unlikely that the existing\u00a0figures can be reconciled.\u00a0 He calculates that the Embry-Riddle Eagle can reach the GFC minimums \u2013 just barely.\u00a0 Looking at the four-passenger Pipistrel Taurus G4, he concludes that it can do more than double the required economy and still manage better than 150 mph at greater than 200 passenger miles per gallon energy equivalent (PMPGe).\u00a0 Hopeful for John McGinnis, but subject to limitations of the spreadsheet, according to Handelman, Synergy may do even better on its total score than the Pipistrel because of Synergy’s higher speeds.\u00a0 He notes that Elektra One, and by inference the Feuling Green Flight Challenger, is at a severe disadvantage being a single place aircraft.<\/p>\n

His spreadsheet allow calculations of fuel use,\u00a0including energy equivalents for\u00a0electric aircraft.\u00a0 For readers who want to do their own handicapping, he provides a generic spreadsheet that can accept tweaks to existing numbers, or incorporate a whole new design.<\/p>\n

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Handelman's nicely-trimmed RV-7A with Catto propeller<\/p><\/div>\n

His home page <\/a>includes his Sport Aviation<\/em> article, \u201cPower and Drag for the Common Man,\u201d and an overview of his own well-turned RV-7A.\u00a0 His interest in aircraft performance measurement, and correspondence with CAFE Foundation luminaries such as Jack Norris, have informed his insights on performance calculation.\u00a0 He notes, for instance, that modern aircraft engines, not having the thrust movement older engines exhibit cannot use Norris\u2019 zero-thrust measurement that was crucial to CAFE\u2019s highly accurate flight measurements.\u00a0 He suggests a torque meter for helping measure newer aircraft\u2019s actual performance.<\/p>\n

Handelman will speak at this year\u2019s AirVenture at 10:oo a. m. on Friday, July 29 in the HomeBuilder\u2019s Hangar, and hopes there\u00a0to continue the ongoing discourse.<\/p>\n

He also carries on a lively discussion on the Homebuilt Airplanes forum<\/a>, which sometimes generates a spirited debate, but always\u00a0searches for verifiable numbers.\u00a0 Howard adds, “Alas, it is worth saying that the ‘truth’ of the calculations is no better than the input.\u00a0 Such things as battery energy density and best glide speed are just educated guess work intended to narrow the range of possible true answers.\u00a0 I don’t want to be or be seen as a know-it-all so much as a good analyst with lots of questions.”<\/p>\n

(Editor’s note: corrected at 2:10 p. m. pdt on July 18, 2011.)<\/p>\n