National Ultralight Inc.
The new 582-powered Challenger Light Sport XL-65 and XS-65 models have a gross weight of 1060 lbs at load factors of +6G/-3G.
The challenge with all airplanes is to keep the empty weight as low as possible to maximize payload and performance. However, people's wants and needs have changed over the years and modern Challengers are heavier than they used to be. Quad City understood the impact of growth in empty weight and incorporated design improvements to increase the maximum gross weight. The maximum takeoff weight has increased from the original 800 lbs to 960 lbs and now with the new XL-65 and XS-65 models to 1060 lbs.
The original Challengers back in 1983 had no doors, no brakes, no streamline fairings, no radio, no electric start, no battery, no lights, no heater, and so on. Needless to say they were very light weight! Many of those features are now considered essential by owners! This has increased the empty weights! Add to this list long range fuel tanks plus pilots who aren't getting any thinner and...
The problem with all virtually all two seat airplanes is that when equipped with floats they essentially become single seat aircraft during the hot, humid summer months. Likewise four seaters become two seaters, six seaters become three seaters, etc. Performance suffers and even becomes dangerous.
The Rotax 582 eliminates this problem by adding power - it has 30% more thrust than a 503. A 582 Challenger on floats flies like a 503 Challenger on wheels. In effect a 582 powered Challenger flies like it is not on floats at all.
The more powerful engine is not the only reason for the increased gross weight on the XL-65 and XS-65. Both models feature a heavy load saddle kit that strengthens the connection where the main lift struts attach to the fuselage. The kit spreads the pull forces from the wing over a wider area where the rony brackets for the struts are bolted to the longeron. The wings are therefore able to pull on the fuselage with more force with the high load kit than without. This kit is available for retrofit on any Challenger but it alone will not increase the gross weight of older Challengers.
Very importantly the XL-65 and XS-65 have the fuel tanks in the wings as a standard feature. The wings have been completely redesigned internally for additional strength to accommodate the two 10 gallon wing tanks. Having the fuel in the wings means that the weight of the fuel formerly in the fuselage does not have to be supported by the wing to fuselage attachments or by the strut to wing and strut to fuselage attachments.
As well, both the XL-65 and XS-65 models have completely redesigned landing gear. The steel weldments that support the gear legs have been heavily reinforced. Formerly the steel cuffs were two separate units set around the two main fuselage longerons. Now the steel cuffs are connected together with a welded steel cross brace that spans the width of the fuselage. In addition, the cuffs are supported by triangular welded steel support rods that are inside the fuselage. These supports brace the gear leg cuffs from forces encountered during landing and taxiing across rough terrain at the higher gross weights.
So, these four new features: more horse power, the heavy load saddle kit, the wing tanks and the beefed up landing gear, all add up to the higher allowable gross weight of 1060 lbs for the XL-65 and XS-65 models.
On floats both models will perform better than any aircraft in their class, even with two people on board, and even on hot summer days. When the primary mission is amphibious floats the XL-65 will be a better choice than the XS-65 due to its larger wing area creating more lift.
Your pilot training taught you about density altitude and its impact on takeoff and climb performance. All this having been said, it is always wise to keep a circumspect eye on your airplane's weight, especially when its hot, humid and/or you are operating at high altitudes.
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