CARBON CLUB

Carbon Cub FX-3: Built to land where almost no one else can reach

The Carbon Cub FX-3 represents the most "muscular" take on the modern Cub concept. It is a high-performance, two-seat aircraft designed for backcountry operations, featuring a 186-hp fuel-injected engine and a constant-speed propeller. With a maximum gross weight of 2,000 lbs (907 kg), this combination boosts payload capacity while upholding the design's core mission: operating in and out of highly restricted areas characterized by uneven terrain and tight operational margins.

The Carbon Cub FX-3 is an Experimental-Amateur-Built (E-AB) aircraft that combines a reinforced airframe with a powertrain designed to convert horsepower into thrust during the flight phases that matter most in backcountry operations: the initial takeoff roll and the initial climb.

On paper, the performance figures are impressive. CubCrafters, the manufacturer, cites demonstrated capabilities that include a takeoff distance of just 90 feet (27.4 meters) and a landing distance of 155 feet (47.4 meters), along with a cruise speed of 135 mph and a range of 765 miles. These figures come with a key caveat: performance was demonstrated with 50% fuel (22 gallons) and an 85-kilogram pilot. In other words, while it is not a generic claim, it also does not reflect the extreme "hot and high" conditions often found in parts of Brazil or South America.

Even so, the combination of a low stall speed (around 37 mph) and a claimed climb rate of up to 2,400 feet per minute explains why the FX-3 is frequently described as a "true STOL" aircraft, rather than just a powerful taildragger.

The decision to raise the FX-3's structural weight limit to 2,000 lbs is the model's standout feature compared to the FX-2 series, which is rated at 1,865 lbs. In a high-wing, STOL-capable two-seater, an increase in maximum weight isn't just a marketing point; it translates into the ability to carry two adults, fuel, and gear without the experience becoming a constant exercise in compromise.

Manufacturer specifications list the FX-3’s payload at up to 977 lb (443 kg)—surpassing the already impressive figures of the FX-2 (400 kg) and earlier generations of the Carbon Cub family. In practical terms, this capacity allows for greater operational flexibility in remote regions—a factor that, in the real world, is just as important as short-takeoff performance.

The payload increase in the EX-3/FX-3 was accompanied by structural changes compared to its smaller sibling, including reinforced rear spars and attachment points, thicker aluminum leading edges, and new XCub-inspired struts. These technical details point to a specific philosophy: the goal isn't merely to carry more weight, but to ensure the aircraft can reliably withstand repeated operations at maximum weight on rough terrain while maintaining a structural safety margin.

A dedicated engine...The FX-3 exists largely thanks to its powertrain. The CC363i is an engine developed by CubCrafters in partnership with Superior Air Parts and Aero Sport Power, specifically designed for the Carbon Cub EX-3 and FX-3. A key highlight is its 186 hp output—an upgrade from the 180 hp CC340 used in the FX-2. It is a fuel-injected, larger-displacement engine featuring cold-air induction and dual electronic ignition (Lightspeed), paired with a composite, constant-speed Hartzell Trailblazer propeller. Consequently, the powertrain generates 20% more thrust than previous Carbon Cub models, providing a greater margin of safety during operations near the aircraft's limits. An interesting detail is the CC363i’s cold air intake, which was developed using CFD tools and involved extensive testing to optimize airflow. The engine was designed with a compression ratio (9.0:1) that prioritizes service longevity, thereby reducing time spent in the shop. Rather than simply chasing peak power, the design philosophy focuses on delivering strong low-end response and operational stability under high thermal loads.

Another highlight is the emphasis on smoothness, efficiency, and cooling, as well as improved tolerance for automotive gasoline and compatibility with new aviation fuels—particularly synthetics. While this was not the project's primary focus, it illustrates the engineering rationale behind the CC363i. Furthermore, the ability to run on automotive gasoline (US standard) expands the FX-3's accessibility in regions with limited or no infrastructure, such as Alaska and other remote areas of North America.

In STOL operations, power is only half the story. The other half is how the aircraft behaves near the stall—during the transition between flight and ground—and how it responds when the pilot needs to place the aircraft exactly where desired. The FX incorporates G-Series ailerons and flaps, along with airfoil modifications designed to improve trim authority and control across the center-of-gravity (CG) range.

The manufacturer describes the ailerons as featuring a new airfoil profile compared to previous models and highlights the repositioning of the hinge point to increase roll authority and provide a lighter, more precise response.

The most technical feature, however, is the flap, which CubCrafters calls "truly slotted." The linkage geometry positions the flap lower relative to the wing when deployed, forcing energized air from the underside to flow over the flap; this keeps the airflow attached and increases lift. This provides greater control and a wider margin at low speeds, directly benefiting short-field approaches and the ability to stabilize the aircraft close to the ground.

The mission package... Another distinction of the FX-3 is that it comes standard with features that are often optional add-ons for many taildraggers. The aircraft is equipped with 44-gallon long-range tanks (39 usable)—essential for missions where fuel availability is uncertain and alternate airports may be distant or isolated. The extended baggage area (featuring a side access door) is described as 48% larger than the standard space, specifically designed to accommodate bulky gear without significantly encroaching on cabin space.

On the ground, the "3x3 HD" landing gear stands out; it is taller to increase propeller-to-ground clearance—a crucial factor for operations in unprepared locations. This type of aircraft goes beyond merely flying on unpaved runways; it is capable of operating in the tightest of spaces anywhere on the planet. The landing gear features a geometry that shifts the axle forward, facilitating more aggressive braking without the touchiness typical of short-coupled taildraggers. Added to this is the Alaskan Bushwheel tail assembly (spring and tailwheel). Finally, there is an LED lighting package with a "wig-wag" function—a small but significant detail for pilots who alternate between remote operations and flying at busier airfields.

Factory eXperimental... The FX (Factory eXperimental) is not merely a technical configuration; it also represents a specific path to ownership. CubCrafters describes a "Builder Assist" process in which the owner participates in the manufacturing and assembly stages under supervision, while the company completes the aircraft to factory standards, all within FAA E-AB (Experimental-Amateur-Built) regulations. The operational appeal for this demographic lies in the ability to perform owner-maintenance and modifications, as well as—depending on configuration and training—expanding the scope of operations, provided applicable regulatory requirements are met.

This "product-plus-process" model helps explain why the FX has become a benchmark in the North American market; it bridges the gap between a raw kit and a finished aircraft while preserving the "experimental" ethos that resonates with the backcountry community—pilots who tend to customize, adapt, and fly with a specific mission in mind. Although this profile is less common in Brazil, the concept could inspire operators who need to fly to locations lacking infrastructure—such as remote areas of large rural estates or isolated indigenous territories—or simply those engaged in adventure flying.

The FX-3 is a logical solution to a specific challenge: how to carry more payload and fly greater distances while still operating in very tight spaces, without turning the aircraft into a heavy machine that is difficult to handle at low speeds. The engineering behind the package—structural reinforcement to 2,000 lbs, a fuel-injected CC363i, a Hartzell Trailblazer constant-speed propeller, and G-Series surfaces—points to a clear objective: expanding utility without compromising the low-speed qualities that define the Cub concept in any pilot's mind.

 

by Vivaero