Tomark Viper

Viper SD-4
Role Two seat ultralight
National origin Slovakia
Manufacturer Tomark s.l.o., Presov
First flight 1 November 2006
Introduction 2008
Number built 26 by November 2010
Unit cost
Ultralight €55,000
LSA €66,000 plus tax.
Rotax 912ULS €1,700 extra (2009 prices).

The Tomark Viper SD-4 is a conventionally laid out, single engine, low wing monoplane with a fixed tricycle undercarriage and side-by-side configuration seating for two, designed and built in Slovakia in the mid-2000s.

Design and development

Design work on the Viper began in 2004, with the first flight on 1 November 2006 and market introduction in 2008. It is intended for touring, training and glider towing. The Viper is constructed mostly of metal, with aluminium skinning. Composite materials are used for the tips of the flying surfaces, the fuselage upper decking, engine cowling and wheel fairings. The wings have constant chord and curved, slightly upswept tips; they are built around one main and one auxiliary spar. The short span ailerons move on piano type hinges, with slotted flaps on the rest of the trailing edges. The low mounted horizontal tail is also of constant chord apart from a cut-out for rudder movement; the starboard elevator carries a flight adjustable trim tab. Fin and rudder are straight edged but swept.[1][2]

The standard Viper is powered by a 60 kW (81 hp) Rotax 912UL flat four engine but the more powerful 75 kW (100 hp) Rotax 912ULS is an option. The forward fuselage is a monocoque, the rear a tube structure with an aluminium skin. The cockpit seats two in side-by-side configuration under a framed single piece canopy, with further transparencies in the fuselage immediately aft. The main undercarriage legs are cantilever springs. The mainwheels are faired and fitted with hydraulic brakes; the nosewheel is also faired and may, as an option, be steerable. Other options include instrumentation, ballistic parachute and towing gear.[1]

Operational history

The first two production aircraft appeared at Aero '07 in April 2007 at Friedrichshafen. Aero '09 saw the first example of the Ultralight version and the announcement of the LSA variant, which has electrically operated trim tab and flaps and flight display and navigation avionics as standard. The latter is heavier, at 327 kg (717 lb) empty; the light-sport aircraft (LSA) regulations allow a higher maximum take-off weight of 560 kg (1,234 lb).[1] It was originally aimed at the French flying clubs[1] but is now being marketed in the USA following certification in October 2010.[3][4] US production at Winnsboro, Texas is under consideration.[3]

By mid-2010 there were 12 Vipers on the European registers excluding Russia, 2 in France and the remainder in Slovakia.[5] By November 2010, 26 had been built.[1]

Variants

Ultralight
Initial baseline version, European ultralight weight limits etc.
LSA
US LSA, with higher maximum take-off weight, electrical flaps and trim and more avionics as standard. LSA approved in August 2010.[2]

Specifications (Ultralight, Rotax 912UL)

Data from Jane's All the World's Aircraft 2011/12[1]

General characteristics

Performance

Avionics


References

Wikimedia Commons has media related to Viper SD-4.
  1. 1 2 3 4 5 6 Jackson, Paul (2011). Jane's All the World's Aircraft 2011-12. Coulsdon, Surrey: IHS Jane's. pp. 533–4. ISBN 978-0-7106-2955-5.
  2. 1 2 Bayerl, Robby; Martin Berkemeier; et al: World Directory of Leisure Aviation 2011-12, page 82. WDLA UK, Lancaster UK, 2011. ISSN 1368-485X
  3. 1 2 "The vibrant Viper". General Aviation News. Retrieved 2 December 2011.
  4. ↑ "Viper SD4". Light Sport Aircraft Pilot News. Retrieved 2 December 2011.
  5. ↑ Partington, Dave (2010). European registers handbook 2010. Air Britain (Historians) Ltd. ISBN 978-0-85130-425-0.


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