The first model is the Viper 4 Series 2 based on a old school simple approach utilizing the original Viper 4 fan duct and small windshield. The craft is powered by a Hirth 3202 which is 55hp @ 5,500 rpm producing 75kg of thrust.
The Flex hub has been omitted form this model, in preference to a softer HTD drive belt. As standard, it is fitted with a 9 blade fan for those near max capacity, but will cater for a 7 blade fan for those who mostly operate with one to three persons.
The weight of the craft is 215kg using the composite fuel tank and Lithium battery. In heavy duty form, with further hull reinforcement, alloy fuel tank and lead acid battery, the craft weighs a respectable 240kg.
Noise using the 9 blade fan is 72db @ 30m, but the 7 blade produces an amazing 70db @ 30m at full power, making it the quietest 4 person hovercraft on the market.
The second model is the Viper 4S Series 2 using the Viper 5 fan duct, elevators, flow vanes, Flex hub, larger windshield etc. The craft is powered by a Hirth 3203 - 65hp @ 6,300 rpm or Rotax UL582 - 54hp @ 6,400 producing 85-90kg of thrust (depending on the engine type).
The hull is made using more high end composites, allowing it to weigh 220kg using the composite fuel tank and Lithium battery. In heavy duty form, with further hull reinforcement, alloy fuel tank and lead acid battery, the craft weighs a respectable 240kg. The fan noise is slightly less than base model but the exhaust is slightly louder, effectively producing 72db @ 30m at full power.
The new Viper 4 model is a pleasure to fly, with improved stability, greater payload capacity, more thrust per horsepower and lower noise levels compared to the older series. The overall fitment and presentation is much more refined, with all the features of the Viper 5 series.