So you would like to become a weight-shift control "Trike" pilot! GREAT!
There are two levels of pilot training based on what you want to fly.
Light Sport trikes are heavier, faster, two-seat aircraft with greater range and are much more reliable. Light Sport Trikes are available in two "flavors", Experimental Light Sport or Special Light Sport. Before the FAA created the Light Sport category of aircraft, they permitted a limited number of two seat exemption training trikes in order to safely instruct students. Only flight instructors could fly these heavier two seat trikes in solo operation. These trikes are fairly abundant on the used market. Most are powered by the Rotax 582, 2-stroke motors. As Experimental aircraft you can take the 16-hour FAA Repairman course to qualify to perform your own annual condition inspection, which will save you the annual expense of paying an A&P mechanic.
Today FAA-certified Light Sport flight instructors must use new "Special Light Sport" aircraft. These are constructed to joint FAA and Industry approved ASTM Standards. They are NOT Experimental aircraft. Additionally these aircraft must be maintained to the manufacturer's original specifications. These aircraft must be inspected annually (or every 100 hours of operation if used for flight instruction) by an FAA-Certified A&P Mechanic, or someone holding an FAA approved inspection certificate. If you want to take a friend up flying with you, or if you like cross-country flying adventures you will need to become an FAA-certified Sport Pilot and invest in the more substantial Experimental or Special Light Sport aircraft.
Note: The performance of a modern Special Light Sport trike is vastly improved from the days of the two-seat exemption training aircraft. Above are two P&M models with sophisticated electric trim systems; Quik GT450 (cruise speed range: 50 - 80 mph) and the fastest trike in the world the QuikR (cruise speed range: 65 mph - 100 mph) . The reliable Rotax 912 series motors boast an impressive 2,000 hour time between overhaul rating! They are fuel efficient aircraft burning between 2.75 to 5 gallons per hour, depending on cruise speed, climb rate etc. With a 17 gallon fuel tank they have an impressive flight range!
Note: ASTM International, formerly known as the American Society for Testing and Materials (ASTM), is a globally recognized leader in the development and delivery of international voluntary consensus standards. Today, some 12,000 ASTM standards are used around the world to improve product quality, enhance safety, facilitate market access and trade, and build consumer confidence.
Ultralight trikes are very simple light-weight aircraft built for a single occupant. They must comply with FAA weight and performance limitations in order to qualify. In general these aircraft fly low and slow and have a limited range and speed. If you are on a budget or simply want to fly solo close to home and not go to the added time and expense of passing your Sport Pilot exams, then FAR 103 Ultralight flight may be for you! In the Ultralight category you are not required to have a pilot license or formal flight medical.
Though you are not required by the FAA to have training in order to legally fly an ultralight, were you to try to fly one without proper training, you are very likely not to survive the experience! Ultralight pilots like all pilots, need dual instruction in order to become safe aviators, regardless of whether they plan to become a certificated pilot or not. Ultralight pilots must obey all airspace flight rules. Basic knowledge of airspace regulations is necessary to avoid endangering yourself or others. Additionally all pilots must know how to properly assess weather conditions in order to make sound Go - No Go flight decisions.
Unlike Light Sport aircraft, you may legally do all maintenance and repairs on your own ultralight. This can result in a big reduction in the cost of ownership. We recommend you seek the maintenance guidance of experienced pilots before attempting to "go it alone". Most all ultralight aircraft are powered by very simple 2-stroke motors which have a much shorter recommended time between engine overhauls and tend to be less reliable than the larger 4-stroke aircraft engines found in Light Sport aircraft.