Wednesday 17 April 2013

Thorp T 18's/S 18's of New Zealand

The next type of 2 seater homebuilt aircraft to be registered in New Zealand was the Thorp T 18.  The Thorp T 18 was designed in 1963 by John Thorp, who was a professional aircraft engineer of Burbank, California.  He was a prolific designer who counted among his designs the Fletcher FU 24 and the original Piper Cherokee.  Don Taylor's US registered T 18 was the first homebuilt aircraft to circumnavigate the world in 1976.  The T 18 was the most popular metal 2 seat homebuilt design in the 1970's and early 1980's, until the Vans series of aircraft came along.

The Thorp T 18 was designed for easy homebuilding construction and was built from 12 sheets of Aluminium of various thicknesses.  It was originally designed around the cheap and freely available Continental O-290G ground power unit, that could easily be converted to aircraft use, producing 125 HP.  The prototype had exposed cylinder heads and an open cockpit, but it flew so well that it was quickly upgraded to a full cowling and a bubble canopy, with more powerful engines.

The T 18 has evolved over the years, with design input from Lou Sunderland who was also a professional aircraft engineer, and who worked on the redesigns in co-operation with John Thorp.  Later models included the T 18W with a wider fuselage, the T 18C with folding wings to enable it to be trailered (and you could have both with the T 18 CW).  Then there was the S 18 (S for Sunderland) which had a new airfoil, and finally the S 18T which has a tricycle undercarriage.  Plans are still available.

The T 18 was quite small with a length of 5.77 metres (18 feet 10 inches), a wingspan of 6.35 metres (20 feet 10 inches) and a wing area of 86 square feet.  Its empty weight was 454 Kg (1,000 pounds) and MAUW was 725 Kg (1,600 pounds).  With a Lycoming O-320 motor the top speed was 200 mph and the cruising speed was 180 mph, which was pretty fast.

Our first T 18 was ZK-EDF (c/n AACA/43/2) which was built by Greg McNicol of Taradale.  It was first registered on 25/8/76 and its first flight was in December 1976.  I recall that Greg McNicol wanted to be the first to fly a homebuilt aircraft in new Zealand at 200 mph, and I think he achieved that.  It is photo'd here at the 1981 AACA flyin at Mt Hutt.  It was sold to JM Jones of Manaia on 11/1/89.

It was then sold to Maurice Paton of Fernside near Rangiora on 6/7/96, and it is photo'd above at Rangiora by Blue Bus on 8/8/09.  It can be seen that it had not changed much over the 28 years, although I can see one slight change.  It was sold to GK Andrews of Wellington on 14/4/04 and to MB Gawith of Taupo on 26/1/06.

Finally it was sold to KD Foster of Whenuapai on 9/3/07.  He flew it to Australia and return in July 2008.  It was rebuilt and repainted in early 2010 in the above colour scheme, as photo'd at the 2010 Black Sands flyin.  It is now named Go Kiwi 11.

Our second T 18 was ZK-ROD (c/n AACA/384) which was built by Rod Davis of Blenhiem, and was first registered on 28/11/80.  It is photo'd above at the 1981 AACA flyin at mt Hutt.  It was sold to TDW Lang of Hobsonville on 26/6/85 and then to RP Bateup, LM Neil, BD Christie and NT Eggleton of Nelson, on 12/9/86.  It is still current.

Our third T 18 was ZK-KID (c/n AACA/476) which was built by Stewart Kidd of Otatara near Invercargill, and was first registered on 27/3/84.  It is photo'd above at the 1989 AACA flyin at Tairei.  Sadly, it was involved in a ftal crash at Alexandra on 11/10/92, killing Stewart Kidd and his passenger.  It was cancelled on 21/4/93.

Our fourth T 18 was a T 18CW model, ZK-TOP (c/n AACA/751), which was built by Ian Clements and Arthur Aisworth of Christchurch.  It was first registered on 30/3/87.  The above photo was taken at the 1992 AACA flyin at Tauranga.  It was sold to Ian and JG Clements on 1/10/98 and it is still current.

Our fifth T 18 was also a T 18CW model.  ZK-VMS (c/n AACA/200) was built by Tony Schischka of Plimmerton, near Wellington and was first registered on 8/5/87.  It had an updraft engine cooling system..It is photo'd above at the 1990 AACA flyin at Waipukurau.  It was sold to AM Schischka of Greytown on 14/1/09, and it is still current and based at Temuka.

Our sixth T 18 was a S 18 model that had the folding wing modification.  ZK-WMT (c/n WM01) was built by Wayne Matthews of Auckland and was first registered on 16/3/04.  It was first flown by Tony Schischka at Matamata.  It had an O-320 motor and was equipped with long range fuel tanks.  Wayne Matthews carried out several long distance flights including a non-stop circumnavigation of New Zealand and a return flight to Australia from Invercargill to Hobart and return via Lord Howe Island in October/November 2005.  It is photo'd above at North Shore airfield on 27/1/07.  Wayne was planning even longer flights including a trip to Oshkosh, but tragically he was killed when ZK-WMT crashed at the Whenuapai airbase on 26/4/08.

Our seventh T 18 was a T 18CW model, ZK-TIS (c/n AACA 575) that was built by Bob Keith of Manakau.  It was first registered on 6/9/04, and it is photo'd above at Pikes Point airfield on 29/10/05.

It was sold to JE Crockett of Christchurch on 30/9/06, and it is photo'd here at Rangiora on 14/10/06 where it has a red addition to the trim lines.  Mr Crockett moved to Australia and took ZK-TIS with him, and it was canceeled from the New Zealand civil register on 17/9/08.  It was registered in Australia as VH-TIR on 18/9/08 and it is still current there.

And our final T 18 (to date) is a S 18T model.  ZK-MBY (c/n ) was built by Mike Boyle of Auckland and was first registered on 7/9/05.  It has an O-360 motor and has fuel tanks in the leading edges of the wings.  It was first flown on at Matamata 6/10/07, again by Tony Schiscka.  It is photo'd above at the 2010 SAANZ flyin at Tauranga.



  1. I am the son of the new owner of ZK-TOP his name is Rodney. this needs updating also it should mention that ZK-MBY now has a taildragger configuration.