A FRIENDLY FAMILY OF ULTRALIGHT MOTOR GLIDERS

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Piuma Original

The Original Piuma is the quietest and easiest to fly among the various versions and therefore the most suitable as a first construction; the landing gear in chromium-molybdenum, with rubbers shock absorbers, tolerates the hard landings of beginners.

Given the growing interest in minimal ultralights, in 2021, the drawings of the Original Piuma, the Construction Manual and also the Project Book, were improved with new photos, all now available also in English language.

The Original Piuma is the simplest and lightest of the Piuma; with the KFM engine the empty weight is 145 kg and is slightly higher than the 120 kg weight envisaged for minimal ULMs; using the latest generation lightweight single-cylinder Italian engines or an electric motor and limited batteries, together with essential instrumentation, it could perhaps fall into this  category. 

The plans, updated in 2012 and in 2021, include the latest changes made to the author's Original Piuma, which, after many years of flying, has undergone a "restyling" on 2005, as you can see from the photos on the site.

The main changes consist in the remaking of the polystyrene and fiberglass nose with a new connection line to the fuselage and in the fairing of the front wheel, now smaller and also steerable via the pedal. Now there is the option to build a steerable nose gear, as shown in the photos.

In 2014 the plane, in addition to a major overhaul of the engine and mechanical parts, underwent a new restyling, consisting of various changes visible from the numerous photos and easily implemented by the new builders by looking at the photos of the site and the many photos available of the DVD supplied together with the Construction Plans; the main updates were the following:
  • 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

With these improvements the normal speed is 100 Km/h with Rotax 447 engine at 4800 rpm.

Basic peculiarities

  • ULM single seat motorglider made mostly of fabric and wood, with an aluminum alloy tail boom with a small engine.
  • The maximum wing loading is 4,3 lb/sq. ft. This low wing loading allows the motorglider to have low stall and landing speeds. This is a safety characteristic, in the event of an off-airport landing.
  • With the glide ratio of about 16 - 17 and the minimum sink rate of 200 ft/min.; it is possible to use a little 25 HP engine with very low fuel consumption (1 Imp Gal/h).
  • The stall speed is 30 MPH and the take-off speed is normally 34 MPH, but it is possible to fly at 29 MPH, in ground effect. The normal cruising speed is 50 MPH and the VNE is 75 MPH.
  • Construction features:
    1. Conventional 3 axis control with ailerons.
    2. The tapered wings, braced and warped in the tapered portion, have a root chord of 47.2 inches and a tip chord of 21.6 inches. The strut profile is similar to a water drop.
    3. The Rhode St. Genese 36 wing airfoil is plano-convex to 16% of the thickness throughout the wing; the leading edge is very rounded, which gives it a very gentle and progressive stall.
    4. The main landing gear built with Cr-Mb stainless steel, cushioned with rubber shock absorbers, is very near (but in front of) the center of lift. The wheels have brakes and fairings. The standard nose wheel is not steerable and has no shock absorber. But a steerable streamlined option is included. The little tail wheel and the rudder are steerable. This special feature unites the advantages of the classic tricycle configuration on take-off and landing and the good ground handling characteristics of the tail-dragger configuration.
    5. The enclosed cockpit allows you to fly in winter in comfort, and improves the aerodynamics. The instruments panel is big enough for a complete set of instruments. The fuel-tank, located behind the seat, near the center of lift, contains more than 5 Imp Gal. and it is sufficient for almost 4 flight-hours (or much more if soaring).
    6. 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 HP

Construction plans

They have been revised and updated several times (last updates completed in September 2021) with various improvements and modifications compared to the prototype, still flying after 30 years (various videos are visible on Facebook and YouTube).

The Construction Plans consist of 11 detailed drawings with dimensions 100 x 60 cm or more; is included also the Construction Book (36 pages 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 without removing them from the aircraft; all in 5 minutes alone).

Drawing no. 12 is also available as an option, which allows the self-construction of 2 wooden propellers for KFM 107 engines of 25 and 30 HP respectively.

The drawings for the steerable front wheel and a detailed note of the materials, both of the birch plywood parts and of the strips, as well as of the metal details, are also included.

The Project Book with the Use Manual are also provided; there are 55 pages with 30 photos plus 40 graphs and tables, in which structural calculations, the prediction of flight characteristics and the procedures for take-off, flight and landing in various conditions are developed in an easy and understandable way.

A DVD with 3800 photos of the construction phases of the various Piuma with many photos of the completed and flying Piuma and some videos in flight is provided as a very useful aid to builders.

Other useful information for the builders

As a rough indication, the cost of materials, excluding engine and instruments, is around 3500 $ (at 2020 prices); the cost of the engine and the instruments is quite 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 is estimated at about 900 hours, having the metal parts made by a workshop.

The dimensions required for the construction of the 6005-T16 aluminum alloy tail boom are: diameter 127mm (5”) - thickness 1.5 mm (1/16”) - length 5.2m (205”).

Images