12/31/2013. Remarks by Walter van Tilborg and Johan Visschedijk: "The CH 600 series are based on the CH 60, a new design of Chris Heintz and were mainly aimed at builders who required an easy-to-build and easy-to-fly two-seater, with a low-power engine. The Zodiac was built in large number worldwide and in many variants. The CH 600 series have been copied/cloned in many ways, reportedly often without permission from the designer himself.

CH 60: Designation for the prototype aircraft, which was built by Zenair Ltd. in Canada. Powered by a 65 hp JPX/VW1875 engine it was first flown on June 21, 1984.
CH 600 Zodiac: The initial production model, for engines up to 100 hp. The CH 600 had thick profile wings of rectangular planform and was available with a tricycle or tail wheel landing gear. Most aircraft were built with a 64 hp Rotax 582 two-stroke engine or 80 hp Rotax 912 four-stroke engine.
CH 601 Zodiac: This improved version appeared in 1991 and it was initially built with a Rotax 582, but most aircraft received an 80 hp Rotax 912. It had a roomier and wider cabin, retained the constant chord thick profile wings of the CH 600 and, like the CH 600, was available with a tail wheel or tricycle landing gear.
CH 601AG Zodiac: This was a special agplane version, flown as single-seater and with a chemicals hopper in the cabin and spraying equipment under the wings. Only very few aircraft were built to this standard. Engine usually was a Rotax 912.
CH 601HD Zodiac: This model was fitted with the original thick wings, but had a reinforced HD (Heavy Duty) construction. Standard engine was a Rotax 912, but the model was available for the same engine options as in the CH 601HDS.
CH 601HDS Super Zodiac: Introduced in 1991, with new, much thinner profile tapered (trapezoidal) wings of reduced span. This version had an improved performance and initially the standard engine was the Rotax 582L, but later it was often built with the Rotax 912. Other engines fitted included a 100 hp Continental O-200-A, Subaru EA81 and larger VW or VW-based power plants. HDS stood for Heavy Duty Speed.
CH 601HDS Sportster: This variant, which was launched in 1994, had a removable (convertible) cockpit canopy with a separate fixed windshield.
CH 601HDS-M Zodiac: This CH 601HDS sub-model was aimed at the (para) military market and had a modified equipment fit, but it was not proceeded with.
CH 601UL Zodiac: This lower gross weight variant had a decreased fuel capacity and it was based on the standard early CH 601 with the constant chord thick wings. The modifications allowed this model to qualify as ultralight in many countries. It had the same landing gear options as on the other models and standard engine was the Rotax 912.
CH 601DX Zodiac: Introduced in 1999 and developed by Zenair, in association with Rolands Aircrafts in Germany, to comply with the German UL category. This model had improved airfoil wings of thinner and trapezoidal planform. Powered by an 100 hp Rotax 912S engine, it also featured an aerodynamically improved engine cowl and many detail changes.
CH 601XL Zodiac: Introduced in 2002 with many improvements, such as re-contoured canopy, a slightly longer fuselage, electrical flaps and trim, a new composite spring leaf landing gear, a larger baggage compartment and featured an all-new wing design, allowing larger wing tanks. The prototype aircraft was initially flown with an 110 hp Jabiru 3300 engine, but also tested with an 115 hp Lycoming O-235 engine and the Rotax 912S.
CH 601XL QB Zodiac: During 2005 a so called Quick Build kit became available which was built with a choice of engines in the 80 to 120 hp range Jabiru 2200 or 3300, Rotax 912 or 914.
CH 601XL Zodiac SLSA: This version was developed by AMD (Aircraft Manufacturing & Development Co. Inc) and was available as a factory-built aircraft. It appeared in 2005 and was refined to meet the US LSA (Light Sport Aircraft) rules. Engine was an 100 hp Continental O-200-A.
CH 601XL Zodiac XLi: This version was announced by AMD early-2006 and basically the Zodiac SLSA certified for IFR operations.
CH 601XL-B Zodiac: Kit version with a choice of engines, like the Rotax 912 or 914, Jabiru 2200 or 3300, Continental O-200, ULPower UL260iS or UL350iS.
CH 601 "ZenVair": "ZenVair" was a nickname for various models CH 601 aircraft which were powered by a modified GM Corvair car engine. At least eight "ZenVairs" (also noted as "ZenVair 601") had been completed and flown by 2007.

W601 WB: This CH 601 version was built in the USA by Wayne Biettie and powered by a Rotax 912 it was flown during 1997, it had many modifications, mainly in the cabin area.
Twin Zenith: This non-official designation was used for an aircraft built by Jeff Guy in the USA and first flown in 2004. It had two 1600 cc VW engines installed in the wings and featured a tricycle landing gear.

In 2008 the CH 601 model was replaced by the CH 650 Zodiac.

Zenair Ltd, founded in Canada in 1974, transferred the production of kits and marketing rights to the Zenith Aircraft Company in USA in 1992. In the late 1980s, the CH 601 was assembled in Columbia by Agrocopteros, Ltd., mainly as agplane and several dozen were produced. In 1997 the manufacture of kits (mainly for European market) was licensed to CZAW (Czech Aircraft Works s.r.o.), but this was terminated July 2006 and December 2006 Zenair Europe in Belgium was established for marketing and kits were then supplied from the USA.

Roland Aircraft of Germany used to assemble kits of the CH 601 for the German market. When this agreement ended Roland developed its own variants which were marketed as ultralights in Germany and other countries.
Zodiac CH 602XL: This model (also noted as Z-602XL) had a tapered wing planform like in the Zodiac DX, but with a modified profile and standard a Rotax 912 engine. Other changes included electric flaps, refined engine cowl, sunk rivets, and it was available with a tricycle or tail wheel landing gear. However, this unofficial variant was not supported by the original designers of the Zodiac nor by the Zenith/Zenair kits manufacturing company Czech Aircraft Works in the Czech Republic.
Zodiac 602XL/RG: During 2006 Roland Aircraft introduced this variant (also noted as Z-602XL/RG) with a retractable tail wheel landing gear. The main landing gear members retracted forward and the wheels were housed in streamlined fairings under the wings."