From « 329 » to « Privateer » The story of the catamaran-hulled seaplane

[Stargazer]

The 329Amphibian: an ambitious project

Self-proclaimed as "the world's most advanced amphibious airplane", Leader Industries' catamaran hulled seaplane was initially known as the 329Amphibian. Aimed at providing the sportsman or the military "a unique advantage over any other seaplane manufacturer", the "329" was a unique twin-hull amphibian aircraft design with a huge ducted fan mounted on top that resembled no other aircraft. It could be used by the sportsman, commuter, and the Navy Seals and still meet the unique criteria for their respective needs. The desire to create this plane came from a knowledge of what was currently available in the general aviation market place, including kit planes and what the company knew was possible with today's engineering. That is why the design, registered under U.S. Patent # 6,592,073 B1, consciously incorporated many of the best features from established amphibians such as the Renegade, Seawolf, Seawind, Sea Fury, SeaBee, and several kitplane flying boat designs.

The project was publicized in 2002, when newcomer Leader Industries sought funding for the creation of the "329" aircraft. Leader aimed to respond to NASA's Small Business Innovation Research (SBIR) in an effort to achieve engineering capital for the project. It ambitioned to realize prototype construction and production of the aircraft at an efficient and effective pace, and was willing to joint venture with or share rights with members of the aircraft industry who had production capabilities. For this purpose, the company made initial overtures to qualified parties for testing/engineering of this aircraft.


An unusual but promising configuration

Two models of the 329Amphibian were built in 2003: One as a static display to show the uniqueness of the design, and a radio-controlled flying model as proof of concept. The Sea trials from the models proved the design to be as expected, and demonstrated the great look down capability of the design, since the wings, being located well aft of the cockpit, allowed for downward visibility usually only associated with high wing aircraft.

The catamaran twin hulls were seen as the key to the performance of the 329Amphibian. Not only this unique configuration was meant to offer stability and reduced drag, but it provided better balance both in the water and in the air. The twin ellipsoidal hulls allowed the aircraft to hydroplane while landing, taxiing or departing, making for maximum control during water operations. The elliptical hulls allowed the plane to better travel on water and to be more efficient in the air. Beaching or docking the plane was facilitated by the wing section between the hulls, and the landing gear was faired into the catamaran hulls, protruding enough for airport landings without adding significant drag. As for the "Ring Airfoil", it provided vectored thrust offering propulsion efficiencies while stabilizing both laterally and longitudinally. The back of the ducted fan would house control surfaces. Thrust was controlled and quieted by the ducted fan, and because the propeller was encapsulated in a ring airfoil, prop noise was significantly attenuated, allowing urban operations.


Initial collaboration with Embry-Riddle

In 2004, Leader Industries contracted with Embry-Riddle Aeronautical University, which remained on the cutting edge of many new aeronautic technologies. Leader sought to use their expertise in the prototype construction, and they requested that Embry-Riddle accomplish a preliminary design of the 329Amphibian concept to include: preliminary weight estimate; wing design; fuselage layout, including buoyancy of hull shape; engine selection and installation as may be integrated with the ducted fan patents; structural concept; weight and balance; stability and control analysis; static performance (level flight speed, climb performance, takeoff distance); cost estimation; physical configuration; and documentation via CATIA solid model drawings. The preliminary engineering evaluation by Embry-Riddle Aerospace Engineering and Research Center, originally due in September was completed after being delayed by at least three hurricanes. The report revealed that the aircraft embodied everything that had been hoped for and more.

The choice of Embry-Riddle proved to be an auspicious one as they had prior involvement in ducted fans and associated control surfaces. As data was available they were able to expedite analysis. New data placed the maximum speed for the new amphibian at 186 knots (218 mph) and the cruise speed at 160 knots (185 mph). Performance would be improved with the incorporation of composite construction as opposed to the heavier fiberglass material used in the analysis. Additional efficiency and speed increases should result by adapting the rotary engine being developed by Embry-Riddle. It was expected that by refining the design further, it would be possible to reduce drag and improve the aesthetics of the aircraft. A software cost analysis performed by Embry-Riddle, concurrent with the engineering evaluation, showed the new amphibian to be highly competitive due to simplicity of design. Accordingly, a change to composite material was warranted and would leave Leader Industries in a competitive marketing posture.

Leader planned partnership with Embry-Riddle toward development of the prototype amphibian aircraft while working toward funding the full-scale development project in the interim interval. Initial contact was made with some undisclosed which had expressed interest in funding the new amphibian, a group already involved in funding another prototype aircraft.


In 2006, the provided figures for the 329Amphibian were as follows:

- Length: 17.91 ft
- Span: 33.6 ft
- Weight (GTOW): 3524.7 lb
- Weight (empty): 2125.01 lb
- Fan: 4-Blade, 6-inch chord, 5-foot diameter prop.
The pitch angle was set at an angle such that the prop would absorb 210 hp or 70% power at 200 mph in the forward direction.

 

[Stargazer]

Enter Orion Technologies

Early in 2007, John A. Meekins, President of Leader Industries, Inc. was introduced to Bill Husa of Orion Technologies, and fairly soon the two men agreed to form a joint-venture for the purpose of furthering the 329Amphibian concept under the new program name of Privateer. Many improvements and updates were incorporated, with "some of the most advanced techniques available in the aerospace industry". Under the aegis of Orion, the Privateer morphed into "a state-of-the-art configuration", which "brought amphibian design at least 50 years forward" according to Meekins.

The newly-completed design incorporated all of the patent elements of the original bird but excluded those configurational details where Leader Industries (sic) "attempted to modify some of the laws of physics." CFD (Computational Fluid Dynamics) analysis and empirical testing of the unique hull shape was completed by Spring 2008. Initial results of water tow tests had been encouraging, demonstrating a "marked improvement in hull performance and water-borne handling over current state of the art." The Privateer now presented a maximum lift/minimum drag configuration resulting in higher airspeeds than traditional water-borne aircraft.

A very different bird

Apart from it being an amphibian propelled by a ducted fan, there is little in common between the Privateer and its "329" forerunner. The twin hull flying boat design has been replaced by a single fuselage aircraft with two large twin floats, and the wing is now set in low instead of high position. The floats are symmetrical and interchangeable, and a spare float can be installed on either the left or the right side. When on land, the gear is configured as a tri-cycle, not a four-wheeler as is usually the case with floatplanes.

The Privateer’s structure is fabricated primarily of carbon-fiber materials in a unique and efficient multi-celled configuration, resulting in assemblies with superior strength to weight ratios, which can be built using more economical fabrication and assembly techniques than possible with other, more conventional structural configurations. All flight surfaces are constructed as singular units in a reinforced monocoque configuration. The result of this approach is a dramatically lower part count and a nearly self jigging assembly.

The Privateer was increased in size to six seats in order to better serve the projected market. The new low-wing amphibian has interior room enough to incorporate a variety of passenger and/or cargo payloads – the cabin having sufficient room to carry a 4 x 8 sheet of plywood flat on the floor. The new aircraft also incorporates a Walther 601 Turboprop in a pusher configuration, along with a shrouded Hartzell propeller. The multi-bladed prop/shroud combination provides the aircraft with higher propulsive efficiencies, as well as substantially quieter operations. Cruise speed is now projected to be in excess of 200 mph at sea level and 240 mph at 8,000 feet, and the aircraft is also designed to operate from snow.

Most of all, the Privateer presents one major improvement over the initial "329": it is now a very slender, attractive machine, "the first new Amphibian design in over 60 years," as Meekins describes it.


Privateer Industries

Meekins and Husa have set up a separate entity by the name of Privateer Industries to promote the Privateer design and although the project has been around in its various forms for a decade, and the prototype is still in the construction phase, they are confident that the new aircraft is about to create a revolution in the field. "There is no competition! Nothing in its class," noted Husa in an interview. The project is said to be gaining attention from interested parties on a global scale, ranging from the U.S. Department of Defense to Central American countries or European companies, and Privateer Industries foresees a potential for 2,000-2,500 units to be marketed in the future. To that effect, and unlike many certificated aircraft programs, they plan to outsource manufacturing to a company with excess capacity, such as Dornier or Bombardier.

Performance
• Maximum cruise speed (at sea level): 195 kt
• Maximum cruise speed (at 15,000 ft.): 215 kt
• Service ceiling (estimated): 25,000 ft
• Rate of climb (at sea level): 2,100 fpm

Range Performance
• VFR Range (with max fuel & passenger Load): goal is 1,000 mi. (actual range will depend on final fuel tank configuration)
• Range (IFR): 800 miles
Note: fuel load will not be traded off for passengers

Takeoff & Landing Performance
• T/O Distance at Max Takeoff Weight: (5,600 #)
• Water (estimated): 1,200 ft.
• Land: 960 ft
• 50 ft Obstacle: 1,300 ft

Weights
• Empty Weight: 3,600 lb (prototype – production will be lighter)
• Gross Weight: 5,600 lb - 6,000 lb
• Useful Load: 2,000 lb
• Wing Loading: 19.8 psf
• Fuel capacity: 200 gal

External Aircraft Dimensions
• Height on wheels: 12.3 ft
• Length (nose to tail): 43.0 ft
• Wing span: 42.9 ft

Internal Cabin Dimensions
• Internal length (from nose bulkhead to aft cabin): 13.2 ft
• Cabin Height (net internal): 4.4 ft
• Cabin width at shoulder height while seated (net internal): 4.1 ft

Seating
• Typical Crew: 1 Pilot
• Passengers: Five to six (aft seat is bench – might hold three across)

Power Plant
• Walter 601 Turbine
• 724 SHP / 657 SHP continuous

NOTE: All numbers are computed performance numbers and will be verified during actual flight testing

Article compiled and written by Stéphane Beaumort using various sources:

- The Leader Industries website (no longer online)
- A PDF presentation by Paul McChesney, Kyle Schroeder and Brad Smith
- American Flying Boats and Amphibious Aircraft: An Illustrated History, by E. R. Johnson
- General Aviation News - Mar. 9, 2012
- U.S. Patent #6592073
- The Privateer Industries website
- The TechGeeze website
- The Gizmag website

 

[Jemiba]

Many thanks for that great effort, Stéphane !

Although looking much more conservative now, with its single hull,
this change probably was necessary, just to make the design commercially
viable. Two spread the interior volume on two slender fuselages wouldn't
decrease the number of seats, but severely limit the flexibility.
Just sorry, that it isn't very probable, that we'll see a new "Dornier flying boat"
this way, as this company is moe or less a name only, with regards to aviation.