Tomark Viper SD4

Last updated
Viper SD4
Tomark Viper SD4 OM-M730.jpg
RoleTwo seat ultralight
National origin Slovakia
Manufacturer Tomark s.r.o.
First flight1 November 2006
Number built110 by July 2016
Unit cost
Ultralight from €63,000
LSA €65,000 plus tax.

The Tomark Viper SD4 is a Slovak single–engine, all-metal, two-seat low wing monoplane with a fixed tricycle undercarriage and side-by-side seating for two people. The aircraft is built by Tomark s.r.o. of Prešov.


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. [1] [2] [3]

The Viper is constructed mostly of metal, with aluminium skinning, using CNC machining. 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] [3]

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] [3]

The aircraft received its EASA SD4 RTC restricted type certificate in March 2016. [4] In the US it is an accepted light-sport aircraft. [5]

Operational history

The first two production aircraft appeared at AERO Friedrichshafen in April 2007. AERO 2009 saw the first example of the Ultralight version and the announcement of the LSA variant [1] It was originally aimed at French flying clubs [1] but is now being marketed in the USA following certification in October 2010. [6] [7] US production at Winnsboro, Texas is under consideration. [6]

By mid-2010 there were two Vipers registered in France and ten in Slovakia. [8] By November 2010, 26 had been built. [1]


Ultralight aircraft version with maximum gross weight of 472.5 kg (1,042 lb) with a ballistic parachute, for the European market.
Light-sport aircraft version with maximum gross weight of 600 kg (1,323 lb) with a ballistic parachute, for the US market.

Specifications (UL version)

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

General characteristics



See also

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  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 3 Tacke, Willi; Marino Boric; et al: World Directory of Light Aviation 2015-16, page 85. Flying Pages Europe SARL, 2015. ISSN   1368-485X
  4. "Restricted type certificate" (PDF). EASA. 22 March 2016. Retrieved 3 August 2016.
  5. Federal Aviation Administration (5 April 2016). "SLSA Make/Model Directory" . Retrieved 3 August 2016.
  6. 1 2 "The vibrant Viper". General Aviation News. Retrieved 2 December 2011.
  7. "Viper SD4". Light Sport Aircraft Pilot News. Archived from the original on 22 October 2011. Retrieved 2 December 2011.
  8. Partington, Dave (2010). European registers handbook 2010. Air Britain (Historians) Ltd. ISBN   978-0-85130-425-0.