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+====== Energy efficiency of Wright Flyer ======
+// Published 04 November, 2020; last updated 10 December, 2020 //
+<HTML>
+<p>The Wright Flyer:</p>
+</HTML>
+<HTML>
+<ul>
+<li><div class="li">flew around 0.080-0.18m/kJ</div></li>
+<li><div class="li">and moved mass at around .022 – .061 kg.m/J</div></li>
+</ul>
+</HTML>
+===== Details =====
+<HTML>
+<p>The <em>Wright Flyer</em> (<em>Flyer I</em>) was the first successful plane, built in 1903.<span class="easy-footnote-margin-adjust" id="easy-footnote-1-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-1-2729" title='&amp;#8220;The&amp;nbsp;&lt;em&gt;&lt;strong&gt;Wright Flyer&lt;/strong&gt;&lt;/em&gt;&amp;nbsp;(often retrospectively referred to as&amp;nbsp;&lt;strong&gt;&lt;em&gt;Flyer&lt;/em&gt;&amp;nbsp;I&lt;/strong&gt;&amp;nbsp;or&amp;nbsp;&lt;strong&gt;1903&amp;nbsp;&lt;em&gt;Flyer&lt;/em&gt;&lt;/strong&gt;) was the first successful heavier-than-air powered aircraft&amp;#8230;.The Wrights built the aircraft in 1903 using&amp;nbsp;&lt;a href="https://en.wikipedia.org/wiki/Sitka_Spruce"&gt;giant spruce&lt;/a&gt;&amp;nbsp;wood as their construction material.&lt;sup&gt;&lt;a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-NASM-2"&gt;[2]&lt;/a&gt;&lt;/sup&gt;&amp;#8220;&lt;/p&gt; &lt;p&gt;“&lt;em&gt;Wright Flyer&lt;/em&gt;.” In &lt;em&gt;Wikipedia&lt;/em&gt;, October 30, 2020. &lt;a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127"&gt;https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127&lt;/a&gt;.'><sup>1</sup></a></span></p>
+</HTML>
+==== Mass ====
+<HTML>
+<p>According to Wikipedia<span class="easy-footnote-margin-adjust" id="easy-footnote-2-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-2-2729" title='“&lt;em&gt;Wright Flyer&lt;/em&gt;.” In &lt;em&gt;Wikipedia&lt;/em&gt;, October 30, 2020. &lt;a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127"&gt;https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127&lt;/a&gt;.'><sup>2</sup></a></span>:</p>
+</HTML>
+<HTML>
+<ul>
+<li><div class="li"><strong>Empty weight:</strong> 605 lb (274 kg)</div></li>
+<li><div class="li"><strong>Max takeoff weight:</strong> 745 lb (338 kg)</div></li>
+</ul>
+</HTML>
+==== Energy use per second ====
+=== Fuel use per hour ===
+<HTML>
+<p>A 1904 article in the Minneapolis Journal says the plane consumed ‘a little less than than ten pounds of gasoline per hour’.<span class="easy-footnote-margin-adjust" id="easy-footnote-3-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-3-2729" title="&amp;#8220;At the speed of 1200 revolutions per minute the engine develops sixteen-brake horsepower, with a consumption of a little less than ten pounds of gasoline per hour.&amp;#8221; "><sup>3</sup></a></span> A pound of gasoline contains around 20MJ<span class="easy-footnote-margin-adjust" id="easy-footnote-4-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-4-2729" title='&amp;#8220;Gasoline has an energy density of about 45 megajoules per kilogram (MJ/kg)&amp;#8221;&lt;br&gt;&lt;br&gt;“Energy Density of Gasoline &amp;#8211; The Physics Factbook.” Accessed November 3, 2020. &lt;a href="https://hypertextbook.com/facts/2003/ArthurGolnik.shtml"&gt;https://hypertextbook.com/facts/2003/ArthurGolnik.shtml&lt;/a&gt;.&lt;br&gt;&lt;br&gt;45MJ/kg = 20.4MJ/lb'><sup>4</sup></a></span> So we have:</p>
+</HTML>
+<HTML>
+<p>Hourly fuel consumption: 10lb/h x 20MJ/lb = 200MJ/h = 55kJ/s</p>
+</HTML>
+<HTML>
+<p>We don’t know how reliable this source is. For instance, a 1971 book, <em>The Write Brothers’ Engines and their Design</em> does not give data on fuel consumption in their table of engine characteristics for lack of available comprehensive data<span class="easy-footnote-margin-adjust" id="easy-footnote-5-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-5-2729" title='&amp;#8220;No fuel consumption figures are given, primarily because no comprehensive data have been found. This is most probably because in the early flight years, when the Wrights were so meticulously measuring and recording technical information on the important factors affecting their work, the flights were of such short duration that fuel economy was of very minor importance.&amp;#8221;&lt;/p&gt; &lt;p&gt;Hobbs, Leonard S. &lt;em&gt;The Wright Brothers’ Engines and Their Design&lt;/em&gt;. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. &lt;a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm"&gt;https://www.gutenberg.org/files/38739/38739-h/38739-h.htm&lt;/a&gt;.'><sup>5</sup></a></span>, suggesting that its authors did not consider the article strong evidence, though it is also possible that they didn’t have access to the 1904 article.</p>
+</HTML>
+=== Utilized motor power / efficiency ===
+<HTML>
+<p>To confirm, we can estimate the plane’s energy use per second by a second means: combining the claimed power (energy/second) made use of by the engine, and a guess about how much fuel is needed to deliver that amount of energy.</p>
+</HTML>
+== Utilized motor power ==
+<HTML>
+<p>According to Wikipedia, the plane had a 12 horsepower (9 kJ/s), gasoline engine.<span class="easy-footnote-margin-adjust" id="easy-footnote-6-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-6-2729" title='&amp;#8220;Since they could not find a suitable automobile engine for the task, they commissioned their employee&amp;nbsp;&lt;a href="https://en.wikipedia.org/wiki/Charlie_Taylor_(mechanic)"&gt;Charlie Taylor&lt;/a&gt;&amp;nbsp;to build a new design from scratch, effectively a crude 12-horsepower (9-kilowatt)&amp;nbsp;&lt;a href="https://en.wikipedia.org/wiki/Gasoline_engine"&gt;gasoline engine&lt;/a&gt;.&lt;sup&gt;&lt;a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-4"&gt;[4]&lt;/a&gt;&lt;/sup&gt;&lt;br&gt;&lt;br&gt;“&lt;em&gt;Wright Flyer&lt;/em&gt;.” In &lt;em&gt;Wikipedia&lt;/em&gt;, October 30, 2020. &lt;a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127"&gt;https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127&lt;/a&gt;.'><sup>6</sup></a></span> The 1904 Minneapolis Journal article put it at 16 horsepower (12 kJ/s), and Orville Wright, quoted by Hobbs (1971), puts it at ‘almost 16 horsepower’ at one point.<span class="easy-footnote-margin-adjust" id="easy-footnote-7-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-7-2729" title='&amp;#8220;Speaking of the first engine, Orville Wright wrote, &amp;#8220;Since putting in heavier springs to actuate the valves on our engine we have increased its power to nearly 16 hp and at the same time reduced the amount of gasoline consumed per hour to about one-half of what it was.&amp;#8221;&amp;#8221;&lt;/p&gt; &lt;p&gt;Hobbs, Leonard S. &lt;em&gt;The Wright Brothers’ Engines and Their Design&lt;/em&gt;. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. &lt;a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm"&gt;https://www.gutenberg.org/files/38739/38739-h/38739-h.htm&lt;/a&gt;.'><sup>7</sup></a></span> Hobbs says that at one point this engine achieved 25 horsepower, though this probably isn’t representative of what was ‘actually utilized’.<span class="easy-footnote-margin-adjust" id="easy-footnote-8-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-8-2729" title='&amp;#8220;In the table, performance is given in ranges which are thought to be the most representative of those actually utilized. Occasionally performances were attained even beyond the ranges given. For example, the 4×4-in. flat development engine eventually demonstrated 25 hp at an MEP of approximately 65 psi.&amp;#8221;&lt;/p&gt; &lt;p&gt;Hobbs, Leonard S. &lt;em&gt;The Wright Brothers’ Engines and Their Design&lt;/em&gt;. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. &lt;a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm"&gt;https://www.gutenberg.org/files/38739/38739-h/38739-h.htm&lt;/a&gt;.'><sup>8</sup></a></span> For that he gives a range of 8.25-16 horsepower.<span class="easy-footnote-margin-adjust" id="easy-footnote-9-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-9-2729" title='See first table in Appendix. It appears that the lower number is for the first flight, though this is confusing:&lt;/p&gt; &lt;p&gt;&amp;#8220;One important figure—the horsepower actually utilized during the first flight—is quite accurately known. In 1904 the 1904-1905 flight engine, after having been calibrated by their prony-brake test-fan method, was used to turn the 1903 flight propellers, and Orville Wright calculated this power to be 12.05 bhp by comparing the calibrated engine results with those obtained with the flight engine at Kitty Hawk when tested under similar conditions. However, since the tests were conducted in still air with the engine stationary, this did not exactly represent the flight condition. No doubt the rotational speed of the engine and propellers increased somewhat with the forward velocity of the airplane so that unless the power-rpm curve of the engine was flat, the actual horsepower utilized was probably a small amount greater than Orville&amp;#8217;s figures. The lowest power figure shown for this engine is that of its first operation.&amp;#8221;&lt;/p&gt; &lt;p&gt;Hobbs, Leonard S. &lt;em&gt;The Wright Brothers’ Engines and Their Design&lt;/em&gt;. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. &lt;a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm"&gt;https://www.gutenberg.org/files/38739/38739-h/38739-h.htm&lt;/a&gt;.'><sup>9</sup></a></span> In light of these estimates, we will use 8.25-16 horsepower, which is 6.15-12 kJ/s.</p>
+</HTML>
+== Efficiency of energy conversion from fuel to motor power ==
+<HTML>
+<p>A quote from Orville Wright suggests fuel consumption as 0.580lb of fuel per horsepower hour.<span class="easy-footnote-margin-adjust" id="easy-footnote-10-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-10-2729" title='&amp;#8220;Orville Wright quotes an early figure of brake thermal efficiency for the 1903 engine that gives a specific fuel consumption of .580 lb of fuel per bhp/hr based on an estimate of the heating value of the fuel they had. This seems low, considering the compression ratio and probable leakage past their rather weak piston rings, but it is possible.&amp;#8221;&lt;/p&gt; &lt;p&gt;Hobbs, Leonard S. &lt;em&gt;The Wright Brothers’ Engines and Their Design&lt;/em&gt;. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. &lt;a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm"&gt;https://www.gutenberg.org/files/38739/38739-h/38739-h.htm&lt;/a&gt;.&lt;/p&gt; &lt;p&gt;Note that the quote says bhp/h, but we think it must mean bhp.h.&lt;/p&gt; &lt;p&gt;Also, bhp is &amp;#8216;brake horsepower&amp;#8217;, meaning horsepower measured empirically through a particular mechanism:&lt;/p&gt; &lt;p&gt;&amp;#8216;Brake horsepower (bhp) is the power measured using a brake type (load) dynamometer at a specified location, such as the crankshaft, output shaft of the transmission, rear axle or rear wheels.&amp;#8217;&lt;br&gt;&lt;br&gt;“Horsepower.” In &lt;em&gt;Wikipedia&lt;/em&gt;, November 3, 2020. &lt;a href="https://en.wikipedia.org/w/index.php?title=Horsepower&amp;amp;oldid=986863945"&gt;https://en.wikipedia.org/w/index.php?title=Horsepower&amp;amp;oldid=986863945&lt;/a&gt;. '><sup>10</sup></a></span> This would imply 23% of energy was utilized from the fuel.<span class="easy-footnote-margin-adjust" id="easy-footnote-11-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-11-2729" title='fuel/power = 0.580lb fuel / hp.h &lt;br&gt;= 0.580 * &lt;a href="https://aiimpacts.org/?p=2729&amp;amp;preview=true#easy-footnote-bottom-4-2729"&gt;20MJ&lt;/a&gt; / hp.h &lt;br&gt;= 11.6MJ/ 745J.h/s &lt;br&gt;= 11600kJ / (0.745 * 3600 kJ) &lt;br&gt;= 4.3. &lt;br&gt;&lt;br&gt;Thus power/fuel = 0.23.'><sup>11</sup></a></span></p>
+</HTML>
+<HTML>
+<p>Hobbs notes that this seems low, but assumes a similar efficiency: 24.50%. Thus he presumably doesn’t find it implausible.<span class="easy-footnote-margin-adjust" id="easy-footnote-12-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-12-2729" title='&amp;#8220;Assuming a rich mixture, consumption of all the air, and an airbrake thermal efficiency of 24.50% for the original engine&amp;#8230;&amp;#8221;&lt;br&gt;&lt;br&gt;Hobbs, Leonard S. &lt;em&gt;The Wright Brothers’ Engines and Their Design&lt;/em&gt;. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. &lt;a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm"&gt;https://www.gutenberg.org/files/38739/38739-h/38739-h.htm&lt;/a&gt;.'><sup>12</sup></a></span></p>
+</HTML>
+<HTML>
+<p>According to Wikipedia, the thermal efficiency of a typical gasoline engine is 20%<span class="easy-footnote-margin-adjust" id="easy-footnote-13-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-13-2729" title='&amp;#8220;Typically, most petrol engines have approximately 20%(avg.) thermal efficiency, which is nearly half of diesel engines. However some newer engines are reported to be much more efficient (thermal efficiency up to 38%) than previous spark-ignition engines.&lt;sup&gt;&lt;a href="https://en.wikipedia.org/wiki/Petrol_engine#cite_note-5"&gt;[5]&lt;/a&gt;&lt;/sup&gt;&amp;#8220;&lt;br&gt;&lt;br&gt;“Petrol Engine.” In &lt;em&gt;Wikipedia&lt;/em&gt;, August 20, 2020. &lt;a href="https://en.wikipedia.org/w/index.php?title=Petrol_engine&amp;amp;oldid=973981680"&gt;https://en.wikipedia.org/w/index.php?title=Petrol_engine&amp;amp;oldid=973981680&lt;/a&gt;.'><sup>13</sup></a></span>. It seems that this has increased<span class="easy-footnote-margin-adjust" id="easy-footnote-14-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-14-2729" title="See above note."><sup>14</sup></a></span>, which would suggest that the typical figure was lower in 1903. We don’t think this undermines the more specific figures given above.</p>
+</HTML>
+<HTML>
+<p>It seems likely that Hobbs number is best here, since he knows about Wright’s number, and may have more information than us about for instance the exact fuel being used. So we use 24.5%.</p>
+</HTML>
+== Calculation of energy use from motor power/efficiency ==
+<HTML>
+<p>Combining these numbers, we have:</p>
+</HTML>
+<HTML>
+<p>power spent = 6.15-12 kJ/s used by engine x 1 / 24.5% fuel energy needed to get one unit of energy used by engine, given inefficiency</p>
+</HTML>
+<HTML>
+<p>= 25-49 kJ/s</p>
+</HTML>
+=== Calculation of energy use ===
+<HTML>
+<p>We now have:</p>
+</HTML>
+<HTML>
+<ul>
+<li><div class="li">energy expenditure calculated via motor power and efficiency: 25-49 kJ/s</div></li>
+<li><div class="li">energy expenditure calculated via hourly fuel use: 55kJ/s</div></li>
+</ul>
+</HTML>
+<HTML>
+<p>Neither figure seems clearly more reliable, so we will use the range 25-55kJ/s</p>
+</HTML>
+==== Distance per second ====
+<HTML>
+<p>Two of the Wright Flyer’s first flights were 120 feet in 12 seconds and 852 feet in 59 seconds.<span class="easy-footnote-margin-adjust" id="easy-footnote-15-2729"></span><span class="easy-footnote"><a href="#easy-footnote-bottom-15-2729" title='&amp;#8220;His first flight lasted 12 seconds for a total distance of 120 feet (37&amp;nbsp;m) – shorter than the wingspan of a&amp;nbsp;&lt;a href="https://en.wikipedia.org/wiki/Boeing_747"&gt;Boeing 747&lt;/a&gt;, as noted by observers in the 2003 commemoration of the first flight.&lt;sup&gt;&lt;a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-WDL-1"&gt;[1]&lt;/a&gt;&lt;a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-5"&gt;[5]&lt;/a&gt;&lt;/sup&gt;&amp;#8230;The last flight, by Wilbur, was 852 feet (260&amp;nbsp;m) in 59 seconds, much longer than each of the three previous flights of 120, 175 and 200 feet (37, 53 and 61&amp;nbsp;m).&amp;#8221;&lt;/p&gt; &lt;p&gt;“&lt;em&gt;Wright Flyer&lt;/em&gt;.” In &lt;em&gt;Wikipedia&lt;/em&gt;, October 30, 2020. &lt;a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127"&gt;https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;amp;oldid=986246127&lt;/a&gt;.'><sup>15</sup></a></span> This gives speeds of 3m/s and 4.4m/s. We will use the second, since it better represents successful flight, still within the first days.</p>
+</HTML>
+==== Distance per Joule ====
+<HTML>
+<p>We now have (from above):</p>
+</HTML>
+<HTML>
+<ul>
+<li><div class="li">speed = 4.4 m/s</div></li>
+<li><div class="li">energy use = 25-55 kJ/s</div></li>
+</ul>
+</HTML>
+<HTML>
+<p>Thus, on average each second the plane flies 4.4m and uses 25-55kJ, for 0.080-0.18m/kJ.</p>
+</HTML>
+==== Mass.distance per Joule ====
+<HTML>
+<p>We have:</p>
+</HTML>
+<HTML>
+<ul>
+<li><div class="li">Distance per kilojoule: 0.080-0.18m/kJ</div></li>
+<li><div class="li">Mass: 274-338kg</div></li>
+</ul>
+</HTML>
+<HTML>
+<p>This gives us a range of .022 – .061 kg.m/J</p>
+</HTML>
+<HTML>
+<p id="block-501d3537-b05b-415d-8040-d337eae506e4"><br/>
+<br/>
+<em>Primary author: Ronny Fernandez</em></p>
+</HTML>
+===== Notes =====
+<HTML>
+<ol class="easy-footnotes-wrapper">
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-1-2729"></span>“The <em><strong>Wright Flyer</strong></em> (often retrospectively referred to as <strong><em>Flyer</em> I</strong> or <strong>1903 <em>Flyer</em></strong>) was the first successful heavier-than-air powered aircraft….The Wrights built the aircraft in 1903 using <a href="https://en.wikipedia.org/wiki/Sitka_Spruce">giant spruce</a> wood as their construction material.<sup><a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-NASM-2">[2]</a></sup>“
+                  <p>“<em>Wright Flyer</em>.” In <em>Wikipedia</em>, October 30, 2020. <a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127">https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127</a>.<a class="easy-footnote-to-top" href="#easy-footnote-1-2729"></a></p>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-2-2729"></span>“<em>Wright Flyer</em>.” In <em>Wikipedia</em>, October 30, 2020. <a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127">https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127</a>.<a class="easy-footnote-to-top" href="#easy-footnote-2-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-3-2729"></span>“At the speed of 1200 revolutions per minute the engine develops sixteen-brake horsepower, with a consumption of a little less than ten pounds of gasoline per hour.” <a class="easy-footnote-to-top" href="#easy-footnote-3-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-4-2729"></span>“Gasoline has an energy density of about 45 megajoules per kilogram (MJ/kg)”<br/>
+<br/>
+                  “Energy Density of Gasoline – The Physics Factbook.” Accessed November 3, 2020. <a href="https://hypertextbook.com/facts/2003/ArthurGolnik.shtml">https://hypertextbook.com/facts/2003/ArthurGolnik.shtml</a>.<br/>
+<br/>
+MJ/kg = 20.4MJ/lb<a class="easy-footnote-to-top" href="#easy-footnote-4-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-5-2729"></span>“No fuel consumption figures are given, primarily because no comprehensive data have been found. This is most probably because in the early flight years, when the Wrights were so meticulously measuring and recording technical information on the important factors affecting their work, the flights were of such short duration that fuel economy was of very minor importance.”
+                  <p>Hobbs, Leonard S. <em>The Wright Brothers’ Engines and Their Design</em>. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. <a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm">https://www.gutenberg.org/files/38739/38739-h/38739-h.htm</a>.<a class="easy-footnote-to-top" href="#easy-footnote-5-2729"></a></p>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-6-2729"></span>“Since they could not find a suitable automobile engine for the task, they commissioned their employee <a href="https://en.wikipedia.org/wiki/Charlie_Taylor_(mechanic)">Charlie Taylor</a> to build a new design from scratch, effectively a crude 12-horsepower (9-kilowatt) <a href="https://en.wikipedia.org/wiki/Gasoline_engine">gasoline engine</a>.<sup><a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-4">[4]</a></sup><br/>
+<br/>
+                  “<em>Wright Flyer</em>.” In <em>Wikipedia</em>, October 30, 2020. <a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127">https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127</a>.<a class="easy-footnote-to-top" href="#easy-footnote-6-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-7-2729"></span>“Speaking of the first engine, Orville Wright wrote, “Since putting in heavier springs to actuate the valves on our engine we have increased its power to nearly 16 hp and at the same time reduced the amount of gasoline consumed per hour to about one-half of what it was.””
+                  <p>Hobbs, Leonard S. <em>The Wright Brothers’ Engines and Their Design</em>. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. <a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm">https://www.gutenberg.org/files/38739/38739-h/38739-h.htm</a>.<a class="easy-footnote-to-top" href="#easy-footnote-7-2729"></a></p>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-8-2729"></span>“In the table, performance is given in ranges which are thought to be the most representative of those actually utilized. Occasionally performances were attained even beyond the ranges given. For example, the 4×4-in. flat development engine eventually demonstrated 25 hp at an MEP of approximately 65 psi.”
+                  <p>Hobbs, Leonard S. <em>The Wright Brothers’ Engines and Their Design</em>. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. <a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm">https://www.gutenberg.org/files/38739/38739-h/38739-h.htm</a>.<a class="easy-footnote-to-top" href="#easy-footnote-8-2729"></a></p>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-9-2729"></span>See first table in Appendix. It appears that the lower number is for the first flight, though this is confusing:
+                  <p>“One important figure—the horsepower actually utilized during the first flight—is quite accurately known. In 1904 the 1904-1905 flight engine, after having been calibrated by their prony-brake test-fan method, was used to turn the 1903 flight propellers, and Orville Wright calculated this power to be 12.05 bhp by comparing the calibrated engine results with those obtained with the flight engine at Kitty Hawk when tested under similar conditions. However, since the tests were conducted in still air with the engine stationary, this did not exactly represent the flight condition. No doubt the rotational speed of the engine and propellers increased somewhat with the forward velocity of the airplane so that unless the power-rpm curve of the engine was flat, the actual horsepower utilized was probably a small amount greater than Orville’s figures. The lowest power figure shown for this engine is that of its first operation.”</p>
+<p>Hobbs, Leonard S. <em>The Wright Brothers’ Engines and Their Design</em>. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. <a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm">https://www.gutenberg.org/files/38739/38739-h/38739-h.htm</a>.<a class="easy-footnote-to-top" href="#easy-footnote-9-2729"></a></p>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-10-2729"></span>“Orville Wright quotes an early figure of brake thermal efficiency for the 1903 engine that gives a specific fuel consumption of .580 lb of fuel per bhp/hr based on an estimate of the heating value of the fuel they had. This seems low, considering the compression ratio and probable leakage past their rather weak piston rings, but it is possible.”
+                  <p>Hobbs, Leonard S. <em>The Wright Brothers’ Engines and Their Design</em>. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. <a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm">https://www.gutenberg.org/files/38739/38739-h/38739-h.htm</a>.</p>
+<p>Note that the quote says bhp/h, but we think it must mean bhp.h.</p>
+<p>Also, bhp is ‘brake horsepower’, meaning horsepower measured empirically through a particular mechanism:</p>
+<p>‘Brake horsepower (bhp) is the power measured using a brake type (load) dynamometer at a specified location, such as the crankshaft, output shaft of the transmission, rear axle or rear wheels.’<br/>
+<br/>
+                  “Horsepower.” In <em>Wikipedia</em>, November 3, 2020. <a href="https://en.wikipedia.org/w/index.php?title=Horsepower&amp;oldid=986863945">https://en.wikipedia.org/w/index.php?title=Horsepower&amp;oldid=986863945</a>. <a class="easy-footnote-to-top" href="#easy-footnote-10-2729"></a></p>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-11-2729"></span>fuel/power = 0.580lb fuel / hp.h<br/>
+                  = 0.580 * <a href="https://aiimpacts.org/?p=2729&amp;preview=true#easy-footnote-bottom-4-2729">20MJ</a> / hp.h<br/>
+                  = 11.6MJ/ 745J.h/s<br/>
+                  = 11600kJ / (0.745 * 3600 kJ)<br/>
+                  = 4.3.<br/>
+<br/>
+                  Thus power/fuel = 0.23.<a class="easy-footnote-to-top" href="#easy-footnote-11-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-12-2729"></span>“Assuming a rich mixture, consumption of all the air, and an airbrake thermal efficiency of 24.50% for the original engine…”<br/>
+<br/>
+                  Hobbs, Leonard S. <em>The Wright Brothers’ Engines and Their Design</em>. [For sale by Supt. of Docs., U.S. Govt. Print. Off.]; First Edition. Smithsonian Institution Press, 1971. <a href="https://www.gutenberg.org/files/38739/38739-h/38739-h.htm">https://www.gutenberg.org/files/38739/38739-h/38739-h.htm</a>.<a class="easy-footnote-to-top" href="#easy-footnote-12-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-13-2729"></span>“Typically, most petrol engines have approximately 20%(avg.) thermal efficiency, which is nearly half of diesel engines. However some newer engines are reported to be much more efficient (thermal efficiency up to 38%) than previous spark-ignition engines.<sup><a href="https://en.wikipedia.org/wiki/Petrol_engine#cite_note-5">[5]</a></sup>“<br/>
+<br/>
+                  “Petrol Engine.” In <em>Wikipedia</em>, August 20, 2020. <a href="https://en.wikipedia.org/w/index.php?title=Petrol_engine&amp;oldid=973981680">https://en.wikipedia.org/w/index.php?title=Petrol_engine&amp;oldid=973981680</a>.<a class="easy-footnote-to-top" href="#easy-footnote-13-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-14-2729"></span>See above note.<a class="easy-footnote-to-top" href="#easy-footnote-14-2729"></a>
+</div></li>
+<li><div class="li">
+<span class="easy-footnote-margin-adjust" id="easy-footnote-bottom-15-2729"></span>“His first flight lasted 12 seconds for a total distance of 120 feet (37 m) – shorter than the wingspan of a <a href="https://en.wikipedia.org/wiki/Boeing_747">Boeing 747</a>, as noted by observers in the 2003 commemoration of the first flight.<sup><a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-WDL-1">[1]</a><a href="https://en.wikipedia.org/wiki/Wright_Flyer#cite_note-5">[5]</a></sup>…The last flight, by Wilbur, was 852 feet (260 m) in 59 seconds, much longer than each of the three previous flights of 120, 175 and 200 feet (37, 53 and 61 m).”
+                  <p>“<em>Wright Flyer</em>.” In <em>Wikipedia</em>, October 30, 2020. <a href="https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127">https://en.wikipedia.org/w/index.php?title=Wright_Flyer&amp;oldid=986246127</a>.<a class="easy-footnote-to-top" href="#easy-footnote-15-2729"></a></p>
+</div></li>
+</ol>
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