Thorp T-18

{{Short description|American homebuilt aircraft}} {{Use mdy dates|date=February 2022}} {{Use American English|date=February 2022}}  {{Infobox aircraft |name= T-18 |image=T18 in flight.jpg |caption=Thorp T-18 in flight |type=Amateur-built aircraft |manufacturer=Eklund Engineering |designer=John Thorp |first_flight= 1963 |introduction= |produced= |number_built=400 |variants= }} thumb|right|Thorp T-18 right|thumb|T-18

The '''Thorp T-18''' is an American, two-place, all-metal, plans-built, homebuilt aircraft designed in 1963 by John Thorp.<ref name="Eklund">{{cite web|url = http://www.thorpt18.com/|title = Eklund Engineering|accessdate = 2009-05-26|last = Eklund Engineering|authorlink = |date = n.d.}}</ref><ref name="WDLA11">Bayerl, Robby; Martin Berkemeier; et al: ''World Directory of Leisure Aviation 2011–12'', page 98. WDLA UK, Lancaster UK, 2011. {{ISSN|1368-485X}}</ref><ref name="WDLA15">Tacke, Willi; Marino Boric; et al: ''World Directory of Light Aviation 2015–16'', page 105. Flying Pages Europe SARL, 2015. {{ISSN|1368-485X}}</ref>

The aircraft was originally designed as an open cockpit aircraft, powered by a military surplus Lycoming O-290G ground power unit engine, but evolved into a fully bubble canopied aircraft powered by engines of up to {{convert|200|hp|kW|0|abbr=on}}.<ref name="Eklund" />

==Design and development== The T-18 was designed to be easily constructed from sheets of aluminum, and use a modified Lycoming O-290G. It was originally designed with an open cockpit and with the cylinder heads protruding through the engine cowling in the interest of simplicity. Even as originally designed, the cruising speed was quite high. The design showed great potential for higher performance and so modifications were created to install larger, cowled Lycomings and a bubble canopy. These modifications allow a T-18 with {{convert|125|hp|kW|0|abbr=on}} to cruise at {{convert|160|mph|km/h|0|abbr=on}} and higher-powered examples to cruise in excess of {{convert|200|mph|km/h|0|abbr=on}}. Some aircraft have been constructed with retractable landing gear.<ref name="Bowers">Bowers, Peter M. ''Guide to Homebuilts – 9th Edition'', pages 124–127. Tab Books, 1984. {{ISBN|0-8306-2364-7}}</ref><ref name="Plane and Pilot">Plane and Pilot: ''1978 Aircraft Directory'', page 157. Werner & Werner Corp, Santa Monica CA, 1977. {{ISBN|0-918312-00-0}}</ref>

These performance improvements made the T-18 one of the most popular homebuilt designs of the 1970s and early 1980s until the Van's Aircraft RV kitplane series came on the market.<ref name="Bowers"/><ref name="Plane and Pilot"/>

The T-18 was designed to use the {{convert|125|hp|kW|0|abbr=on}} Lycoming O-290G Ground Power Unit. At the time the T-18 was developed, these engines were inexpensive and widely available as military surplus generator motors. When converted for aircraft use they are virtually identical to the O-290D or O-290D2 aircraft engines.<ref name="Eklund"/>

Other Lycoming engines can be used, including the Lycoming O-320, Lycoming O-340, Lycoming O-360 and the Lycoming IO-360.<ref name="Eklund"/>

T-18 plans were available to builders from Eklund Engineering, which was also developing a laser-cut kit version and as of 2009 had aileron, flap and empennage kits. Classic Sport Aircraft at one time supplied plans, parts, and kits for the S-18 and the S-18T tricycle gear version, but went out of business in 2014.<ref name="Eklund"/><ref name="ClassicPrice">{{cite web|url = http://www.classicsportaircraft.com/price.html|title = Kit and Component Pricing|accessdate = 2009-05-26|last = Classic Sport Aircraft|authorlink = |date = n.d.|url-status=dead|archiveurl = https://web.archive.org/web/20081206122216/http://www.classicsportaircraft.com/price.html|archivedate = 2008-12-06}}</ref> Thorp Central acquired the assets of Classic Sport Aircraft and now provides S-18 plans and parts.<ref name="ThorpCentral">{{cite web|url = http://www.thorpcentral.com/|title = Thorp Central |accessdate = 24 November 2014|last = Grahn|first = Jim and MaryKay|date = }}</ref>

By 2011 over 1600 sets of plans had been sold and 400 examples were flying.<ref name="WDLA11"/>

==Operational history== One T-18, N455DT, was built by Donald Taylor of California and flown around the world from Oshkosh, Wisconsin, in 1976. This was the first successful circumnavigation of the world by a homebuilt aircraft. Taylor subsequently flew N455DT to the geographical North Pole, using a Sperry hybrid inertial navigation system.<ref name="EAAMuseumT18">{{cite web|url = http://www.airventuremuseum.org/virtual/interactive/innovations/thorp/|title = Thorp T-18|accessdate = 2009-11-21|last = EAA AirVenture Museum|authorlink = |year =}}</ref>

Clive Canning flew another T-18 from Australia to England earlier the same year.<ref name="COF1976">{{cite web|url = http://www.century-of-flight.net/Aviation%20history/aviation%20timeline/1976.htm|title = World Aviation in 1976|accessdate = 2009-11-28|last = Century of Flight|authorlink = |year = |archive-date = May 15, 2009|archive-url = https://web.archive.org/web/20090515114542/http://www.century-of-flight.net/Aviation%20history/aviation%20timeline/1976.htm|url-status = dead}}</ref>

==Variants== ;T-18 :Original model ;T-18W :Modified T-18, with changes designed by Lou Sunderland to provide a {{convert|2|in|cm|abbr=on}} wider fuselage. ;T-18C :Modified T-18, with changes designed by Lou Sunderland to provide a "convertible" wing that rotates back against the fuselage for trailering or storage. ;T-18CW :T-18 with wider fuselage and folding wing. ;S-18 :Similar to T-18CW, with modified airfoil and other minor changes. The Sunderland changes were made in collaboration with Thorp.<ref name="KitplanesDec2011">Vandermeullen, Richard: ''2012 Kit Aircraft Buyer's Guide'', Kitplanes, Volume 28, Number 12, December 2011, page 48. Belvoir Publications. {{ISSN|0891-1851}}</ref> thumb|Thorp S-18T ;S-18T :Tricycle landing gear version<ref name="WDLA11"/><ref name="WDLA15"/><ref name="ClassicPrice"/><ref name="KitplanesDec2011"/>

==Specifications (S-18 with Lycoming O-360)==

{{Aircraft specs |prime units?=imp  |ref=''Eklund<ref name="EklundSpecs">{{cite web|url = http://home.jps.net/~eeicorp/id47.htm|title = T-18 specifications|accessdate = 2009-05-27|last = Eklund Engineering|date = n.d.|url-status=dead|archiveurl = https://web.archive.org/web/20080228173158/http://home.jps.net/~eeicorp/id47.htm|archivedate = 2008-02-28}}</ref> & Classic Sport Aircraft<ref name="ClassicSpecs">{{cite web|url = http://www.classicsportaircraft.com/performance.html|title = Performance|accessdate = 2009-05-27|last = Classic Sport Aircraft|date = n.d.|url-status=dead|archiveurl = https://web.archive.org/web/20081207074446/http://www.classicsportaircraft.com/performance.html|archivedate = 2008-12-07}}</ref> & Thorp Central<ref name="s18_thorp_central">[http://thorpcentral.com/the-s-18 "S-18,"] Thorp Central, retrieved January 20, 2024</ref>''  |crew=one |capacity=one passenger and {{convert|600|lb|kg}} loaded weight |length ft= 18 |length in= 10 |length m=5.77 |span ft=20 |span in=10 |span m=6.35 |height ft=5 |height in=1 |wing area sqft= 86 |wing area sqm= 8 |empty weight lb=1000 |gross weight lb=1600 |more general=  |eng1 name=Lycoming O-360 |eng1 hp=180 |eng1 kw=135 |prop name=constant speed propeller, ||prop blade number=2 |prop dia in=72 |prop dia m= 1.83  |max speed mph= 200 |max speed kmh= 320 |cruise speed mph= 180 |cruise speed kmh= 292 |stall speed mph= 63 |stall speed kmh= 101 |range mi= 540 |range km=875 |range note=, {{convert|900|mi|km|abbr=on}} with optional wing tanks |climb rate ftmin= 1500 |climb rate ms= 7.6 |wing loading lb/sqft=18.6 |wing loading kg/m2=90 |power/mass=8.9 lb/hp (0.19 kW/kg) |more performance=  |armament= |avionics=

}}

==See also== {{aircontent |see also= |related= *Thorp T-211 |similar aircraft= *Jeffair Barracuda *Mustang Aeronautics Mustang II *Smyth Sidewinder *Stoddard-Hamilton Glasair II *Van's Aircraft RV-6 |lists= |similar engines= }}

==References== {{reflist|30em}} {{commons category|Thorp T-18}}

Category:Homebuilt aircraft Category:1960s United States civil utility aircraft Category:Low-wing aircraft Category:Single-engined tractor aircraft Category:Aircraft first flown in 1963 T-018 Category:Aircraft with fixed conventional landing gear Category:Single-engined piston aircraft