Earthstar Adds Hirth F-33 Engine to Gull 2000 Options

Single-Cylinder 25-Horse Engine With Powerfin Prop

Above: Earthstar Aircraft has a new engine/propeller combination to offer buyers of their latest Thunder Gull ultralight, the Gull 2000. Right: The 25-hp single-cylinder Hirth F-33 2-cycle engine and Powerfin E Model 3-blade composite prop produces a smoothness "uncharacteristic of a single-cylinder engine," Earthstar claims. The empty weight of the Gull 2000 with this engine/prop combination is only 236 pounds (well under FAR Part 103's 254-pound limit for single-seat U.S. ultralights), according to Earthstar.

Earthstar Aircraft, manufacturer of the Thunder Gull line of single-seat ultralights and 2-seat ultralight trainers and light sport aircraft, is offering a new engine/prop combination on their Thunder Gull 2000* single-seat ultralight. The Gull 2000 features a 4130 chromoly steel fuselage mated to an aluminum wing and tail section.

"Testing has been completed on the Gull 2000 ultralight with the 25-hp Hirth F-33 [single-cylinder 2-cycle] aircraft engine and the Powerfin E Model 3-blade composite propeller," the company reports.

Earlier this year, Earthstar was testing the single-cylinder 26-hp Zanzottera MZ 34 2-cycle engine, which "had a wide power band and good performance, but had a lot of vibration," says Earthstar president and Thunder Gull designer Mark Beierle. Since then, Beierle has installed the Hirth F-33 and the Powerfin prop. "This combination flies the Gull 2000 quite well, with very little vibration," Beierle claims. He has about 35 hours on the engine, belt drive and prop combination and indicates it performs very similarly to a single-cylinder 26-hp Rotax 277 2-cycle engine, "but a lot smoother, and with phenomenal fuel economy." Using the F-33 engine and Powerfin propeller, "the Gull 2000 can fly along at cruise speed with as little as 3,800 rpm," Beierle says.

"The smoothness of [the Hirth F-33 and Powerfin prop] combination is uncharacteristic of a single-cylinder engine," Earthstar notes.

Significantly for ultralighters flying under the provisions of Federal Aviation Regulation Part 103, the new engine and prop reduce the total empty weight of the Gull 2000 to 236 pounds, well under the 254-pound maximum empty weight requirement for Part 103 single-seat ultralights in the United States.

"It gives the kind of performance I am used to, but with very little weight," says Beierle. The Gull 2000's 236-pound empty weight allows pilots to add additional instruments, navigation or communication equipment (like a GPS unit or aircraft transceiver) or other systems, and still stay under the Part 103 weight limit.

Report filed by Dave Loveman with Buzz Chalmers * See "UF! Pilot's Report: Single-Seat Gull 2000 - Excellent as Always," January '01 Ultralight Flying! magazine.

Info: Earthstar Aircraft, PO Box 706, Dept. UF, Santa Margarita, CA 93453.
Phone: (805) 438-5235 * Fax: (805) 438-4938 * e-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .