Commanding flight of the Thunder Gull at Arlington EAA fly-in.

Mark Beierle’s ideal airplane didn’t exist, of course. An adult might have dismissed the boy’s ideas with a brief laugh and forgotten all about it. But not Mark. He’s spent several decades of his life designing into one airplane the best combination possible and then polishing the result. He flew the latest version, the Thunder Gull 2000, from California to the Arlington, Washington EAA fly-in this past July.

Behind Mark’s pleasant demeanor lies a passionate love for flying and a penetrating insight into what makes the Thunder Gull perform the way it does. A first-time visitor might easily miss the depth of understanding and experience in his simple words, the same way as many people overlook the polished perfection of Longfellow’s poetry or the enigmatic beauty of the Mona Lisa painting.

Above: The weight and positioning of the battery and the ballistic chute, allows the nosewheel to remain on the ground when empty. Below: Beierle proudly sthows his refined Odyssey 2000 in Washington.

Mark’s experience includes many years of work with aviation companies such as General Dynamics, Teledyne Ryan and Matrix. Projects which he headed or participated in included building cruise missile and wind tunnel models, plus radar and computer equipment.

Mark began flying aircraft as a child and soloed at 16. Through the years, he became familiar with working on and restoring a variety of planes. During this time he continued to develop and test his own designs, even selling kits and plans for successful models.

Typically, he can be seen munching on a big bowl of salad like the wiry, outdoors type that he is, while casually mouthing pearls of aerodynamic wisdom. Above all, he is a thinker and a doer. Perhaps the greatest acknowledgment of his genius is the fact that Mark’s ideas are copied by some of his most successful competitors.

In 1988 Mark presented the world with his first Thunder Gull prototype. His goal was a small, light, inexpensive ultralight that combined his childhood ideas of the perfect airplane. Since then he has added the Power Glider "J" and "Soaring Gull" versions, the two-seat tandem "JT2", the side-by-side "Odyssey" and the new Gull 2000. Each of these can be built from kits as ultralights or ultralight trainers. (Trainers are two-seaters under 495 pounds with 10 gallons fuel, whereas single-seat ultralights are 254 pounds max with 5 gallons.)

Above: Mark points out the location of the ballistic chute in the cockpit area. Below: The sophisticated look of the Odyssey sitting level at rest.

Refinements to the Gull 2000 include increased cockpit comfort to accommodate larger people. The fully-enclosed cockpit is wider and the door is larger than previous models. Seat travel adjustment is a full eight inches.

The nose is also longer, allowing the battery and ballistic chute to be placed up front. The weight holds the nosewheel on the ground when the plane is empty rather than back on its tail like most other ultralights. This makes cockpit access easier without the plane tilting as you ease in or out. It also makes the Gull safer in gusty conditions. Besides, Mark simply likes the looks of it better with it sitting level.

There is a removable panel on the nose for maintenance of instruments, battery and chute. The chute is mounted to fire vertically through the nose panel. A cable is routed from it alongside the windshield up to the center of the wing. This arrangement lowers the aircraft level to the ground onto its wheels after an in-flight deployment, further enhancing safety and minimizing damage.

The tail boom was lengthened six inches to balance the heavier nose. Mark says that is more than needed, but the extra length makes the Gull 2000 even more stable. Increased weight in the nose also allows shifting the engine farther back behind the trailing edge. The extra distance gives airflow off the wing more time to stabilize before going through the prop, reducing vibration. This also eliminates prop pulses felt as the prop passes the back of the fuselage.

The fuselage itself has been computer-analyzed and changed to reduce drag by almost half. On the flight from California to Arlington in his new Gull 2000, Mark says he averaged 30 miles per gallon of fuel, proving the changes translate into longer range and fewer fuel stops. Thunder Gulls have already been flown coast to coast many times. This one is another step in Mark’s personal odyssey toward creating the ideal light airplane.

Flying characteristics: The Thunder Gull design is noted for stability and very little adverse yaw. Mark says you can fly with feet on the floor and steer with minimal input to the control stick. This stability is great for long-distance flying, but the plane can also be very nimble both on the ground and in the air. Roll rate for the new Gull 2000 (measured from a 45 degree tilt of the wing to 45 degrees on the other side while flying straight ahead) is only 1.8 seconds!

Significantly, all of the Thunder Gulls have a "G" loading of +6 and -4 (ie. the airframe can withstand six times its "gravity" weight in upward stress or four times downward). One has been flight tested to +5.9G, an unusual accomplishment for an ultralight aircraft.

Above: The secret of its strength and handling is the cantilevered wing. Below: Specially designed wingtips further enhance efficiency.

The secret of this strength and handling combination is a cantilevered (no struts) wing with a high-lift, low-drag airfoil. Mark designed special wingtips which further enhance efficiency. The result is a short wing that performs better than many much longer ones.

Control surfaces are covered in fabric rather than aluminum like other parts of the wing and tail. This avoids having to counterbalance the ailerons and rudder with lead which would otherwise be necessary at higher speeds. VNE (velocity never exceed) is 120 mph, though cruise can be restricted to ultralight speeds. A cockpit-adjustable trim system is provided for hands-off cruising.

The Odyssey and JT2 have large, powerful flaps for short-landing capability. They have lots of reserve power and lift for take-off and climb even with full flaps down. Take-off distance ranges between 125 to 200 feet, with landing distances from 175 feet in the JT2 down to a mere 75 in a single-seat Thunder Gull!

Kits are available for all the Thunder Gull designs, or they can be bought ready-to-fly. Frames are welded chromoly steel. Kits include such things as independent brakes for the fiberglass landing gear, shoulder harness and aluminum wing-skin.

Building time is as low as 150 hours for the single-seaters and 300 to 350 hours for two-seat planes. Ultralight versions meet FAR 103 requirements, though all kits can be registered as experimental aircraft. A new Odyssey 2000 kit without engine, instruments and prop costs $10,965.

Contact:

Earthstar Aircraft, Inc.
Route 313
Santa Margarita,
California 93453
Telephone: (805) 438-5235
Email: thundergul@aol.com 
WebSite: www.thundergull.com