A FRIENDLY FAMILY OF ULTRALIGHT MOTOR GLIDERS

Piuma Original

The Piuma Original has the lowest wing loading of all the versions and for this reason it is also the most suitable for pilots with little experience; the main landing gear in chromium-molybdenum, cushioned with rubber bands, allows landings that are not exactly textbook.

Quick and easy to build, it is also the lightest; with the KFM engine, the empty weight is 230 lb and is slightly higher than the limit expected for minimal ULMs; using the latest generation small single-cylinder Italian engines or an electric motor and limited batteries, with essential instrumentation, it could perhaps fall into this category.

The drawings, the Construction Book and the Project Book, all available also in English, were revised and improved in 2021 and are now clearer and simpler, complete with new details, graphs, tables, as well as the changes introduced in the “restyling” of 2005 and 2014, also visible in the numerous photos on the DVD; the changes at a glance:
  • Cowling droplet profiles Carbon Fiber and Epoxy main landing gear and fairing rubber band
  • Formation of a new rounded fairing under the fuselage
  • Rounding and re-profiling of the rear fuselage part under the engine
  • Rounded reconstruction of the connection to the tail boom of the vertical plane
  • Makeover with the new shape of the top of the Fin and Rudder new shape
  • Realization of a new fairing rounded tail wheel
  • Replacement of old drum brakes with new mountain bike disc brakes
  • Trim for the tailplane
  • New carbon dashboard with sun protection and new radio mount
  • Cowling for the engine and new electric start, now with LiFePO4 battery
  • Steerable front wheel connected to the pedals and enclosed

With these improvements the normal speed is 59 MPH with Rotax 447 engine at 4800 rpm.

Construction features

  • Single-seat ULM motorglider in wood and fabrics with aluminum alloy tail boom, propulsion engine and wing loading of only 4,1 lb/sqft, with consequent low stall speeds (30 MPH) and landing speeds. Cruising speed is around 55 MPH (VNE = 75 MPH).
  • Being light and with a low descent rate (efficiency around 17) a 25-35 HP motor of limited cost and low consumption is sufficient.
  • It as 3-axis controls and air-brakes are present; the wings (braced with a single strut) are tapered and twisted at the ends for a smooth and progressive stall, also obtained thanks to a flat-convex profile at 16% thickness and a very rounded nose.
  • The cockpit is closed (maximum comfort and aerodynamics). The instruments panel is big enough for a complete set of instruments while the 25 liter fuel tank, placed behind the seat, near the center of gravity, allows a range of almost 4 hours of flight.
  • Dimensions & areas, weight & loadings, performances, engine:
    Wing span
    Total wing area
    Aspect ratio
    Dihedral
    Total tailplane area
    Lever arm of tail plane
    Length overall
    Max height
    Empty weight
    Max take-off weight
    Max wing loading
    Recommended load factors
    Ultimate load factors
    Max level speed
    Normal cruising speed
    Stalling speed
    Never exceed speed
    Best glide ratio with power off
    Take-off
    Landing
    Max climb rate at sea level
    Min sink rate (at 36 MPH)
    Engine
    38.4 ft
    125 sq.ft
    11.2

    17.2 sq.ft
    10.7 ft
    19.4 ft
    4.6 ft
    320 lb
    518 lb
    4.14 lb/sq.ft
    + 3.4 - 1.2
    + 6.8 - 2.5
    59 MPH
    50/55 MPH
    30 MPH
    75 MPH
    17
    330 ft
    330 ft
    390 ft/min
    200 ft/min
    25-35 HP

Construction plans

The Plans consist in n.11 drawings with dimensions 39” x 24” or more. The 40-page Construction Book with 80 photos and many diagrams and drawings, including the one to build the mechanism that allows you to remove the wings and fold them parallel to the fuselage in 5 minutes by themselves (without removing them from the aircraft); there are also drawings for making the steerable front wheel. Obviously the Construction Book contains a detailed note of the necessary materials, from birch plywood to spruce or linden fillets, as well as metal details, glues, resins, dacron cloth, etc.

It is also available, as an option and on request, the drawing n. 12 which allows the self-construction of 2 wooden propellers for KFM 107 engines of 25 and 30 HP respectively.

The Project Book is also provided, including the Use Manual; there are 66 pages with 30 photos plus 40 graphs and tables, in which the structural calculations, the prediction of the flight characteristics, the determination of the Center of Gravity and the methods for take-off, flight and landing are developed in an easy and understandable way.

Also included is a DVD with 3800 photos of the construction phases of the various Piuma, many photos of the completed and flying Piuma and some in-flight videos, videos which are always visible on Youtube and Facebook (see the links at the bottom of all pages of the website).

Other useful information for the builders

As an indication, the cost of materials, excluding the engine and instruments, is around 5,000 $ (at 2023 prices); the cost of the engine and instruments is somewhat variable, depending on the choice of the type of new or used engine and on the more or less essential instrumentation; from the photos you have a broad overview of the possibilities offered.

The construction time can be estimated at about 900 hours, having the metal parts made by a workshop.

The tail boom is made of 6005-T16 aluminum alloy in the dimensions: external diameter of 127 mm (5”)- thickness 1.5 mm (1/16”)- length 5.2 m (205”); by adapting the fuselage fittings, it is also possible to use slightly different tubes, as long as their bending strength is not lower than that of the tube above (bending strength values are in the Project book).

Images