A New Carbon Composite Powered Ultralight Glider

Sagitta 3-View

l would like to present a few photos and a technical description of a powered glider that my colleagues and I have developed over the past 20 months. The glider is designed so that it meets Federal Aviation Regulations (FAR) Part 103 -Ultralight Vehicles.

2014-02-22-1 - Sagitta UL Powered Glider

I have been involved in designing and building composite fuselages and other parts for various UL aircraft for over 20 years. I have built the motorized glider Sagitta with my colleague Vadimir Duchacek. Static and flight tests were performed by LAA inspector Milos Dedera, one of the best glider pilots in the Czech Republic. The glider exhibits stable behavior even at a stall speed of 45 km/h, and the rudder is effective at this speed. Landing speed is 50 km/h without flaps. Descent speed at 90 km/h is 0.6 m/s.

The UL aircraft rudder is very effective at speeds above 130 km/h; it is due to the efficiency of the rudder at low speeds. The tail wheel is built into the rudder, and with the added winglet at the end of the wing, turned in the downward direction. With a mounted wheel, the aircraft will be able to taxi around an airfield from hangar to runway and execute turns with a radius of 6 m. The engine will be fastened in front of the vertical tail area and aerodynamically shielded to achieve the least resistance, or engine pull-out and pull-in on the fuselage. Our effort to build a clean aerodynamic aircraft is also motivated by the possibility of adoption of electric power. This aircraft should reach its maximum flying parameters at low energy consumption. These are some of the main parameters of the motor UL glider Sagitta.

  • Wing  span                                           11m
  • Length                                                  5,8m
  • Wing area                                              8m2
  • Empty weight                                        115kg
  • MTOW                                                    230kg                                                                                   
  • Load factor                                            4,4/-2,2 G
  • Max. speed Vne                                     150km/h
  • Max. speed in turbulence Vb                 120km/h
  • Stall speed                                               45km/h
  • Min. sink with  90 km/h                          0,6m/s
  • L/D                                                          35
  • Climb performance with MTOW              +2 m/s
  • Fuel tank in the wings, capacity           19 litres

You can view a photo and video of Sagitta's takeoff and landing at http:/www.uschovna.CZ .

Here are some additional photos of the glider.

DSCN0493 DSCN0511 DSCN0547 2013-10-03 11.20.29


  10 comments for “A New Carbon Composite Powered Ultralight Glider

  1. Jarno Nieuwenhuize
    February 24, 2014 at 6:36 am

    It seems to me you guys are nowhere near FAR103 criteria. Stall speed is far too high for a powered FAR103-compliant aircraft (24 kts max) and empty weight is far too high to fall into the sailplane category (155 lbs, 70 kg)

    • Radek
      February 24, 2014 at 11:58 pm

      24 kts /45 km/h, 28 mph/

  2. Jarno Nieuwenhuize
    February 25, 2014 at 4:49 am

    A typical (3D!) Clmax for a flapped sailplane is around 1.5, probably a tad less for your Re numbers. You would have to obtain a 3D Clmax of 3.1 Even with triple slotted Fowler flaps that seems unrealistic.

    The alternative in FAR103 (the formula), I think allows a Clmax of 1.6 for your flap area, which would mean you’d still have to double wing area to be compliant.

    In your defence, many, if not almost all manufacturers use totally unrealistic numbers for stall speed.

  3. May 30, 2014 at 12:37 pm

    Link to uschovna goes to the main page, not the video.

  4. May 30, 2014 at 12:39 pm

    As to the stall speed, my fat airplane with stubby wings stalls at 35 mph. And look at this honking aspect ratio. The weight is lower, too (mine is not the true Part 103 ultralight). I can’t see why touching 28 mph in this would be unrealistic.

    • Jarno Nieuwenhuize
      January 25, 2015 at 3:08 am

      Those pesky laws of physics? His claims are not “unrealistic”, but downright impossible.

      Your “fat airplane” very likely doesn’t stall at 35 mph either. IAS is notoriously unrealible at higher angles of attack, but both owners and marketing folks of course dig those kind of numbers…

  5. September 14, 2014 at 9:13 pm

    • Wing span 11m 36.08923884514436 Feet
    • Length 5,8m 19.02887139107612 Feet
    • Wing area 8m2 86.11128333367778 square feet
    • Empty weight 115kg 253.5316015126092 pounds
    • MTOW 230kg
    • Load factor 4,4/-2,2 G
    • Max. speed Vne 150km/h 93.2056788356001 mph
    • Max. speed in turbulence Vb 120km/h 74.56454306848008 mph
    • Stall speed 45km/h 27.96170365068003 mph
    • Min. sink with 90 km/h 0,6m/s
    • L/D 35
    • Climb performance with MTOW +2 m/s
    • Fuel tank in the wings, capacity 19 litres 5.01926899480482 gallons

  6. Gils
    October 7, 2014 at 4:04 am

    0,6 m/s at 90 km/h ==> L/D is over 41…

    • Radek
      October 7, 2014 at 12:58 pm

      Sagitta with the engine was done a few test flighta.

      He is the approximate result further tests are probably nonso optimistic.


  7. johannes
    January 6, 2015 at 11:43 am

    will this be produced as a kit or complete glider?
    what engine is there in the tail?
    looks like the windex 1200

Comments are closed.