STOL CH 801 - © Cetin BAL - GSM:+90 05366063183 -Turkiye / Denizli

FUSELAGE DESIGN: The square-shaped fuselage and cabin offer maximum usable space for occupants and cargo. The four-seat STOL CH 801 cabin is designed to fit a stretcher along the right side of the aircraft (with the co-pilot seat removed), while still providing adequate space for the pilot and one passenger. The rear seat cabin area can be used for hauling bulky cargo.

Of course, for those using the STOL CH 801 as a sport utility plane, there’s enough room inside for two to camp in, and more than enough baggage area for extended cross-country trips. An optional belly-mounted cargo pod further increases space for baggage.

The cabin area utilizes a 4130 chrome-moly (chromium-molybdenum) welded steel tube frame top assembly. The tube frame allows for maximum visibility, and incorporates attach points for the wings. The lower cabin is made up of a factory-riveted bottom-side assembly that gets joined to the top tube frame. The cabin is fitted with two large doors for easy access to the cabin.

The boxy rear fuselage lends itself for very easy assembly, allowing each of the four ‘flat’ sides to be built individually on a flat workbench, and then simply ‘boxed’ together to form the rear fuselage. The forward fuselage section (cabin area) is build separately, and then joined to the rear fuselage section. The aircraft wings are designed for quick and easy attachment and removal from the fuselage.

Modular Construction: Throughout, construction of the STOL CH 801 kit aircraft is ‘modular’ – each section of the aircraft is built separately on the workbench. Many builders thus choose to buy ‘component kits,’ purchasing kit sections as they progress through the project. The modular construction of the kit means that required workshop space is minimal – most builders construct the kit in a single-car garage or basement workshop.

Once all the airframe sections have been assembled, the wing and tail sections are bolted to the fuselage and the landing gear, controls, and fuel system are installed.

The STOL CH 801 aircraft is built of semi-monocoque stressed-skin all-metal construction, just like modern factory-built planes, but adapted specifically for the kit builder. The airframe sections are designed and built so that the outer surface skin is part of the structure, with internal supports (ribs, bulkheads and longerons) to distribute the loads. The parts are fastened together permanently with rivets.

Sheet-metal construction is outstandingly the most widely used aircraft building method around the world, and has proven itself as an ideal aircraft building material since the early pioneering days of aviation. Modern alloys are lightweight, strong, corrosion-resistant and durable, while being easy to work with.

Unlike most other all-metal kit aircraft, the STOL CH 801 kit is made for the first-time builder, and is easy and quick to build, requiring no special skills, tools or jigs to assemble in a workshop, such as a single car garage or basement workshop.

Sturdy and low-fatigue aluminum alloys make the STOL CH 801 airframe very rugged and corrosion resistant, making it ideally suited for "bushplane" operations. The modern 6061-T6 aluminum-alloy used in the STOL CH 801 construction is durable and corrosion resistant, ideal for even the harshest environment, and very easy to repair and maintain on the field. The owner of a STOL CH 801 is assured of a long airframe life, with minimum required maintenance, as metal is not adversely affected by ultra-violet (UV) light and temperature changes like fabrics, Dacron or composites (it’s thus feasible to tie-down the aircraft outdoors to minimize costs).

"The truest gauge by which to measure the quality of a kit and its kit manufacturing company are the number of its satisfied customers, the fine flying characteristics of all its finished aircraft, and the dedicated after-purchase support provided by the factory.
"By all these standards and many others too numerous to mention, Zenith Aircraft Company's excellent reputation is well deserved. We heartily recommend to every prospective homebuilt kit buyer that he or she seriously consider the excellent aircraft produced by Zenith Aircraft, a company we've always found to be competently and professionally managed by genuinely qualified, dedicated people."
— editor, Sport Pilot magazine

The simple stressed-skin monocoque construction uses single curvature sheet-metal skins riveted to internal structural members.

The sheet-metal skins, main wing spar, structural ribs, longerons, stiffeners and bulkheads are fastened together with Zenith’s proven riveting method using Textron Avex blind rivets, which are as easy to set as ‘pop’ rivets, requiring only a simple hand rivet puller. The corrosion-resistant Avex rivets provide a permanent structural bond and tight low-profile dome finish, formed by the custom riveter head. The rivet stem becomes locked in after being set to provide a water-tight seal. The 1/8-inch and 5/32-inch Avex rivets used are very sturdy and durable fasteners, and may be used over a wide grip area. The blind rivets are much easier and quicker to set than bucked rivets, and don’t require the use of a noisy pneumatic rivet hammer or counter-sunk rivet holes.

"They go together predominantly with aircraft-grade Avex pull-stem rivets, which together with the simplicity of the design make for kits that can actually be assembled in a few hundred hours."
— Kitplanes magazine (01/04)

The sturdy main wing spar is a built up I-beam, with cap extrusions buck-riveted to the spar web. In the kit, the spar comes completely pre-assembled and finished (drilled and riveted, with flanged lightening holes). The rib stations on the spar are even pre-drilled - ready for final wing assembly. The structural aluminum wing ribs and fuselage bulkheads are supplied ready-to-install (pre-formed and finished at the factory with flanged lightening holes).

The surface sheet-metal skins are blind riveted to the spar, ribs and bulkheads. Many flat surface skins are pre-drilled at the factory with a drilling machine, and are pre-formed and cut, ready for assembly.

FUEL SYSTEM: The STOL CH 801 is equipped with dual 15 US gallon (56 liters) welded aluminum wing fuel tanks, located inside the wing behind the main wing spar. The Extended Range Option doubles the number of wing tanks to four, for a total fuel capacity of 60 gallons (224 liters).

The airframe itself is designed to allow maximum customization by the actual builder. The STOL CH 801 is not designed ‘around’ a specific engine, allowing for custom powerplant installations by builders.

The semi-monocoque rear fuselage requires the same type of simple assembly as the wings. The square rear fuselage is easily assembled by assembling each side on a flat workbench and then simply ‘boxing’ the four sides together. The forward fuselage (cabin) is made up of factory-riveted lower side frames, and and a welded 4130 chromium-molybdenum steel top frame. Fuselage and cabin parts are supplied ready for assembly as standard components of the complete kit.

The horizontal stabilizer tail is built up of two spars and internal ribs, covered with the pre-formed aluminum-alloy skin. The elevator is fabricated like the ailerons, and attached to the stabilizer with pins at each end. The pre-formed vertical tail skins cover the internal spar and ribs.

The standard dual welded-aluminum wing tanks hold 15 US gallons each. Optional extended range wing tanks double the fuel capacity.

A short take-off and landing (STOL) aircraft must be able to fly at low controlled speeds, yet it must also offer acceptable cross-country (cruise) performance. The challenge is to design a wing with a high lift coefficient so that the wing area is as small as possible, while allowing for take-off and landing speeds that are as low as possible. Short wings make the aircraft easier to taxi, especially when operating in an off-airport environment with obstructions. They also allow for better visibility, and require less space for hangaring, while also being easier to build and stronger (less weight and wing span to support).

The STOL CH 801 uses a special airfoil design to achieve very high lift, low stall speeds, and high strength. A thick wing, full-length leading-edge slats and trailing edge ‘junker’ type flaperons develop a maximum wing lift coefficient of 3.10, while maintaining a short wing-span – for maximum strength and ground maneuverability.

The stall of the wing occurs at the highest lift coefficient on an airfoil, when the airflow can no longer go around the airfoil’s nose (leading edge) and separates from the upper wing surface. Conventional trailing-edge wing flaps help delay the stall to a higher lift coefficient, but only with limited effectiveness. However, by combining the use of trailing-edge flaps with leading-edge slats, the wing's lift coefficient can be effectively doubled if used on the full span of the wing.

Leading edge slats prevent the stall up to approximately 30 degrees incidence (angle of attack) by picking up a lot of air from below, where the slot is large and accelerating the air in the funnel shaped slot (venturi effect) and blowing this fast air tangentially on the upper wing surface through the much smaller slot. This effectively "pulls" the air around the leading edge, thus preventing the stall up to a much higher angle of incidence and lift coefficient.

The disadvantage of leading-edge slats is that the air acceleration in the slot requires energy (it creates additional drag). While many STOL designs utilize retractable leading-edge slat devices, the additional weight, complexity, reliability issues and cost of such systems minimize their feasibility for use in light aircraft and their overall effectiveness.

TAIL DESIGN: The STOL CH 801 tail sections are designed to provide maximum effectiveness (control) at slow speeds and at high angles of attack.

The horizontal tail sections are made up of the elevator and the stabilizer. Both these sections are unique and developed specifically for maximum effectiveness at low speeds and at high angles of attack. The stabilizer is an inverted airfoil section to maximize downward lift to help achieve high angles of attack required for short take-off and landing performance. The elevator is an actual airfoil section, and provides a ‘virtual venturi’ effect when deflected down, as illustrated below. The unique tail sections provide maximum effectiveness for short take-off and landing performance – while also minimizing the actual size of the tail sections.

The STOL CH 801 makes use of highly engineered design features for excellent STOL performance, and importantly, responsive control at low speeds. While many aircraft designs often boast a low stall speed, many of these same designs have minimal control effectiveness at these lower speeds.

The STOL CH 801's large effective control surfaces provide excellent controllability at very low flying speeds - a necessity for effective short take-off and landing performance - while being very light and balanced.

The adjustable front seats fold forward for easy access to the rear seats / cargo area. With anticipated applications for mission use, the rear seat area can be converted for cargo use (including 50 gallon drums), or the cabin can be reconfigured for a berth (patient on a stretcher) across the front and back right-hand seats, with the pilot in the front left seat and a doctor or nurse in the left rear seat.

The standard tricycle gear configuration maximizes forward visibility when taxiing, while also providing the added benefit of a level cabin while on the ground, to facilitate access to the cabin and to maximize pilot and passenger comfort.

The cabin is fitted with a large instrument panel and dual controls - accessible from both the left and right seats. The standard center-mounted control column (stick) can easily be used from either side, and does not limit visibility of the instrument panel. The dual rudder pedals also steer the nose-wheel (direct linkage), and are equipped with hydraulic toe-brakes (standard on the pilot’s side).

The stock instrument panel measures nearly 41 inches (104 cm.) across and 11 inches (28 cm.) high, providing plenty of room for custom avionics and IFR instrumentation (depth behind the panel is up to 21 inches / 53 cm.). In the kit, the pre-formed instrument panel bulkhead is supplied in 'blank' form to allow the builder to fully customize the layout of instruments.

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