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de Havilland Iris
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<h2 id="design-and-development">Design and development</h2> <p>By 1908 <a href="/facts/Geoffrey_de_Havilland/Cv2LdxnY">Geoffrey de Havilland</a> had designed and built two motorcycle engines and was planning his first aircraft, the <a href="/facts/De_Havilland_Biplane_No._1/WV5RtftF">de Havilland Biplane No. 1</a>. He had studied the engine used by the <a href="/facts/Wright_brothers/byU6xEkD">Wright brothers</a> and believed that he could design a similar unit with an improved <a href="/facts/Power-to-weight_ratio/NykmM0pr">power-to-weight ratio</a>. Whilst working as a designer for the Motor Omnibus Construction Company in London he produced drawings for his new engine over a period of three to four months and commissioned the <a href="/facts/Iris_(car)/GtD5bGtW">Iris Cars Ltd</a>, where his brother Ivon de Havilland had been the Chief Designer, to build it at a cost of £250.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p><p>The design featured a horizontally opposed, four-cylinder layout with a single <a href="/facts/Camshaft/qS8BWXVr">camshaft</a> operating <a href="/facts/Poppet_valve/ADRB6Evc">poppet valves</a> through <a href="/facts/Overhead_valve/zd4v8vWf">pushrods</a> that were hollowed to save weight. The <a href="/facts/Crankshaft/oYCe9nB3">crankshaft</a> was supported on <a href="/facts/Ball_bearing/UarVS4gr">ball bearings</a> which allowed a simple 'splash' lubrication system to be used. Cooling was by water with the <a href="/facts/Cylinder_(engine)/XlMRcfFl">cylinders</a> being encased in <a href="/facts/Copper/I8PEE8oX">copper</a> jackets. The engine ran adequately but was not placed into series production. A small order was received from the <a href="/facts/Government_of_the_United_Kingdom/3zLlUWbx">British Government</a> for use in <a href="/facts/Airship/8X3TSBdx">airships</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> <h2 id="1957-replica">1957 replica</h2> <p>In 1957 instructors and apprentices from the <a href="/facts/De_Havilland/8JjkbUxV">de Havilland Aircraft Company Technical School</a> decided to construct a <a href="/facts/Replica/GTRczTMJ">replica</a> engine, almost 50 years after the original Iris was built. The Iris Motor Company had long since closed and its records, along with the original engine drawings, were destroyed by German bombing during <a href="/facts/World_War_II/2efV5L1U">World War II</a>. <a href="/facts/Flight_International/puw0u5sf"><i>Flight</i> magazine</a> had featured an article on the engine in May 1910 with a detailed technical description and line drawings. This information along with the original designer's memory were used to produce a new set of drawings and components. Several companies involved with the original engine assisted with new parts, <a href="/facts/Claudel-Hobson/fr9HXfN3">Claudel-Hobson</a> supplied the <a href="/facts/Carburetor/DMvC7y9M">carburettor</a>, <a href="/facts/Oliver_Joseph_Lodge/jYCILgvS">Lodge Plugs Ltd</a> the <a href="/facts/Spark_plug/Y9lG10hg">spark plugs</a> and <a href="/facts/Frederick_Richard_Simms/8npI8eGI">Simms Motor Units</a> assisted with re-conditioning a <a href="/facts/Ignition_magneto/9Xpwl27E">magneto</a> that had been borrowed from the <a href="/facts/Science_Museum_(London)/1mwwq0oj">London Science Museum</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p>Connected to a <a href="/facts/Lathe/FjF9FYLR">lathe</a> via a belt drive, the engine started at the first attempt in May 1961 and idled steadily at 2-300 <a href="/facts/Revolutions_per_minute/fdNmLToF">rpm</a>. It is reported that the engine was then displayed in the showroom of the <a href="/facts/De_Havilland_Engine_Company/UctGKW1L">de Havilland Engine Company</a> at <a href="/facts/Leavesden%2c_Hertfordshire/HYAJD1gd">Leavesden</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h2 id="applications">Applications</h2> <ul><li><a href="/facts/De_Havilland_Biplane_No._1/WV5RtftF">de Havilland Biplane No. 1</a></li> <li><a href="/facts/Royal_Aircraft_Factory_F.E.1/AuN4eh9u">de Havilland Biplane No. 2</a></li> <li>Government Balloon Factory Gamma</li></ul> <h2 id="specifications-iris">Specifications (Iris)</h2> <p><i>Data from</i> <i>Lumsden and Flight</i><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></p> <h3>General characteristics</h3> <ul><li>Type: 4-cylinder liquid-cooled <a href="/facts/Flat_engine/MMHDYBzH">horizontally opposed</a> piston aircraft engine</li> <li><a href="/facts/Bore_(engine)/HQjzTl2Y">Bore</a>: 4.5 in (114 mm)</li> <li><a href="/facts/Stroke_(engine)/whnTkDl3">Stroke</a>: 4.75 in (120 mm)</li> <li><a href="/facts/Engine_displacement/qkHXacPv">Displacement</a>: 301.46 cu in (4.94 L)</li> <li><a href="/facts/Dry_weight/Cl8KLRml">Dry weight</a>: 250 lb (113 kg)</li></ul> <h3>Components</h3> <ul><li><a href="/facts/Valvetrain/PMAR1vSR">Valvetrain</a>: Overhead valve</li> <li>Fuel system: <a href="/facts/Carburetor/DMvC7y9M">Carburettor</a></li> <li>Fuel type: <a href="/facts/Gasoline/lcnxq5BS">Petrol</a></li> <li>Cooling system: Water-cooled, <a href="/facts/Thermosiphon/2b19pP49">thermo-siphon system</a></li></ul> <h3>Performance</h3> <ul><li>Power output: 45 hp (33.5 kW) at 1,500 rpm</li> <li><a href="/facts/Power_density/aSQJNy5p">Specific power</a>: 0.15 hp/cu in (6.8 kW/L)</li> <li><a href="/facts/Power-to-weight_ratio/NykmM0pr">Power-to-weight ratio</a>: 0.18 hp/lb (0.3 kW/kg)</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/De_Havilland_Aircraft_Heritage_Centre/hyNASqdl">de Havilland Aircraft Heritage Centre</a></li></ul> <p> Comparable engines </p> <ul><li><a href="/facts/Green_C.4/AmJ5u1zs">Green C.4</a></li></ul> <p>Related lists </p> <ul><li><a href="/facts/List_of_aircraft_engines/WmM6KfAp">List of aircraft engines</a></li></ul> <h3>Notes</h3> <h3>Bibliography</h3> <ul><li><a href="http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201020.html">Gough, Edward. A. <i>The first D.H. engine</i>. <i>Flight</i>, 27 July 1956</a>.</li> <li>Lumsden, Alec. <i>British Piston Engines and their Aircraft</i>. Marlborough, Wiltshire: Airlife Publishing, 2003. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 1-85310-294-6.</li> <li>McKay, Stuart. <i>The Moth - Magazine of the de Havilland Moth Club, No. 150.</i> de Havilland Moth Club Ltd. Berkhamsted, Hertfordshire. June 2010.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>McKay 2010, p. 16. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>McKay 2010, p. 17. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>McKay 2010, pp. 18 - 19. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>McKay 2010, pp. 18 - 19. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Lumsden 2003, p. 136. <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Gough 1956, p. 166. <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> </ol>