Thorp T-18

File:Thorp T-18 amateur-built C-GEMP 02.JPG

Thorp T-18

File:Thorp T18 VH-OTM.jpg

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">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="WDLA11">Bayerl, Robby; Martin Berkemeier; et al: World Directory of Leisure Aviation 2011–12, page 98. WDLA UK, Lancaster UK, 2011. Template:ISSN</ref><ref name="WDLA15">Tacke, Willi; Marino Boric; et al: World Directory of Light Aviation 2015–16, page 105. Flying Pages Europe SARL, 2015. Template:ISSN</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 Template:Convert.<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 Template:Convert to cruise at Template:Convert and higher-powered examples to cruise in excess of Template:Convert. 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. Template:ISBN</ref><ref name="Plane and Pilot">Plane and Pilot: 1978 Aircraft Directory, page 157. Werner & Werner Corp, Santa Monica CA, 1977. Template:ISBN</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 Template:Convert 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">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Thorp Central acquired the assets of Classic Sport Aircraft and now provides S-18 plans and parts.<ref name="ThorpCentral">{{#invoke:citation/CS1|citation |CitationClass=web }}</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">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Clive Canning flew another T-18 from Australia to England earlier the same year.<ref name="COF1976">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Variants

T-18

Original model

T-18W

Modified T-18, with changes designed by Lou Sunderland to provide a Template:Convert 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. Template:ISSN</ref>

File:ThorpS18T.jpg

Thorp S-18T

S-18T

Tricycle landing gear version<ref name="WDLA11"/><ref name="WDLA15"/><ref name="ClassicPrice"/><ref name="KitplanesDec2011"/>