Original Design Light Bush Plane


Project overview:
  • Home built concept of a light-weight bush plane.
  • Short take off and landing operations.
  • powered by twin 65HP engines.
  • Stalls below 40 Knots.
  • Single engine operations.
  • Dead-stick approach characteristics for minimum impact during landing.
  • Range of 150 - 180 Miles.
  • Plausible home-built design.
Main features:
Scientific design and accurate flight modelling with plausible predicted performance.

Virtual 3D cockpit - recommended for field of view setting of 65-75 degrees.

Design and unique features

Main structure:The UL-104 airframe is basically a welded steel/aluminum tube trusses. The fuselage structure is covered by light weight fiberglass aerodynamic cover, and equipped with a light weight plexiglass canopy that is mechanically operated. The airplane is powered by two 65HP reciprocating engines in a pusher configuration, driving wooden, 3-bladed, fixed pitch propellers. It features a conventional tricycle landing gears, with a nose wheel steering mechanism. Wheels and structure are designed for rough surface operations.

Aerodynamic design and features:Main wing is with a dihadral of 9 degrees, not equipped with any control surfaces or flaps, for simple construction and weight saving. A tail boom is connected to each wingtip, following by a "T" tail horizontal stabilizers. Both tail booms are symmetric and identical and can be used both sides during manufacture or construction. The two "T" tails horizontal moving control surfaces are connected to the cockpit by a simple mechanic push/pull system, with a differential mechanism that allow them to move both up and down for pitch (elevator) control, or differentally for roll (aileron) control. Effective roll response is acquried thanks to the lateral position of the "T" tails - one on each side of the wing-span, far from the center (different from a conventional single tail/horizontal stabilizer and elevator). This design saves weight and simplify the structure of the main wing and control mechanism. Both "T" tails are equipped with a rudder control surface that are both equal together (size and area) to a single conventional rudder. Another feature of this design is the ability to control the aircraft in a deep stall, with a sink rate of 1500 feet per second.

Cockpit and systems:Cockpit for one pilot operation. Conventional control stick for elevator and roll control, Pedals for rudded control and nose wheel steering. Throttle control for both engines is made with the left hand, while stick control is made with the right hand. The UL-104 is not designed for iceing and/or storm conditions and is not equipped with anti-ice systems. An artificial horizon is available using a smartphone application, and it's mainly for orientation in mountain environment. Shut-off Fuel handles are located in both side of the cockpit. Canopy handle and locking mechanism is located on the left side of the cockpit.

Flying characteristics:The UL-104 safe short takeoff can be made in 40 Knots IAS, and it's low flying speed characteristics and capability allows it to be flown steeply, "on the stall", to avoid obstacles near the runway. Cruise speed is between 65-75 Knots IAS. The airplane is stable and forgiving. A typical short landing procedure is slowing down and stabilising on a 50 Knots final. When getting closer to the touchdown point, a second slow down to 40 Knots is requiered. In this flying configuration, engine's RPM is relatively high, and aiming the airplane to the touchdown point is a combination of stick control (airspeed) and throttle control (slope or height). In this technique, the airplane is set to touch down on 3 points, and there is no need for a flare; pulling the stick may result in a stall.

The VSKYLABS UL-104 design makes it challenging for the expert pilot, and teaching for the beginner one.

General characteristics Crew: one pilot
Capacity: one passenger
Length: 27 ft
Wingspan: 30.8 ft
Height: 8 ft
Wing area: 200 ft²
Empty weight: 750 lb
Useful load: 120 lb
Max. takeoff weight: 1,200 lb
Powerplant: 2 × 65 hp (48 kW) at 2,350 rpm

Performance Cruise speed: 63 kn
Maximum cruise speed: 85 knots
Vne: 105 knots
Stall speed: 39 knots
Range: 150 - 180 miles
Service ceiling: 12,500 ft
Rate of climb: 650 ft/min at 50 knots