Design DetailThe standard tricycle gear also allows for excellent forward visibility while taxiing - an important consideration when operating the aircraft in off-airport environments. The heavy-duty tricycle gear system was chosen as the standard gear configuration for the STOL CH 750 to meet the needs of today’s pilots: Most pilots are not experienced ‘taildragger’ pilots, and a tricycle gear provides better stability and control on the ground. The STOL CH 750 uses a high tail configuration to allow easy rotation of the aircraft to achieve high lift during take-offs and landings. In a tailwheel configuration this requires a tall and awkward main gear to achieve the same high angle of attack (see illustration). Furthermore, the tricycle gear allows for a level cabin area – this makes loading and unloading the aircraft much easier than with an inclined cabin. In a tricycle gear configuration, the wing is at a neutral angle of attack while the aircraft is on the ground, as opposed to a maximum lift angle with a taildragger. Tailwheel airplanes are thus more susceptible to ground wind conditions while taxiing or even while parked outdoors.
While it’s not the lightest gear system around, it provides excellent rough-field capability when combined with large tires, and is very durable, simple and virtually maintenance-free. The main gear is fitted with 8.00 x 6 wheels and 16-inch treaded tundra tires, with independent hydraulic disk brakes. The nosewheel strut uses a single heavy-duty bungee for shock absorbency. The nosewheel is steerable, with direct linkage to the rudder pedals for very effective and responsive ground handling and tight turns. The main wheels are equipped with independent hydraulic disk brakes. The STOL CH 750's gear has been developed specifically for off-airport use. The direct linkage steerable nosewheel, plus differential braking, provide remarkably precise ground handling and steering.
Often called the 'Sky Jeep' with its new All-Terrain Gear, the STOL CH 750 is ideally suited for off-airport use. The direct linkage steerable nosewheel, plus differential braking, provide remarkably precise ground handling and steering. Click here to view a schematic of the landing gear
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 750 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 Wing Slats:
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 retractible 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.
The wings are braced by dual steel wing struts, and are bolted to the fuselage at the cabin frame with four bolts for easy wing attachment and removal.
ABOVE-CAB WINGS: The aircraft wings are positioned above the cabin and fuselage - this allows for excellent horizontal visibility as the wings are located above the pilot’s head to provide pilot and passenger with superior visibility. In addition, the wings taper at the wing root to meet the ‘skylight’ top window – maximizing upward visibility, a feature especially useful in steep turns. While providing great visibility, the ‘above-cab’ wing design minimizes the frontal area of the aircraft to reduce drag, while also allowing the airflow to travel undisturbed from the propeller to the tail sections – further maximizing slow flight control of the aircraft.
The STOL CH 750 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 750 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 750'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.
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