“Xtra” - a word to make a computer spell-checker stumble – is an appropriate name for this month’s pilot’s report, The New Kolb Aircraft Company Mark III Xtra side-by-side 2-seater. It literally offers extra in several ways pilots will like. The venerable Mark III has been through a series of changes since original company founder Homer Kolb first brought out a 2-seater called the TwinStar. The latest change does a lot to alter the appearance of the older design. Kolb designs have narrow noses like a lot of other designs. The new Xtra presents a clean edge cutting through the air, but it now has a wider look – at least from head-on – that imparts a new feel to the occupants. Some will say the “Xtra” comes from “Extra-Wide.” With its bulging doors, the new cabin is 45 inches wide (42.5 at the hips). Although the design will look bigger and heavier to some, the new shape is one you’ll come to like… if you have a seat.
|160 square feet
|6.25 pounds/square foot
|6 feet 4 inches
|12.5 pounds per hp
|Never exceed speed
|Rate of climb at gross
|Takeoff distance at gross
|Landing distance at gross
|Rotax 582 (tested with Rotax 912), mostly enclosed cabin with wide seating area, instrument pod, folding wings, shared Y-stick, in-flight trim and remote choke (as tested), steerable tailwheel.
|Hydraulic brakes, engines up to 81-hp Rotax 912, dual controls, covering kit, upholstery package, starter kit, quick-build kit, ballistic parachute.
|Welded 4130 chromoly steel fuselage, aluminum wings and boom, fiberglass fairing, steel landing gear, dope-and-fabric wing coverings. Made in the USA by American-owned company.
Cosmetic appearance, structural integrity, achievement of design goals, effectiveness of aerodynamics, ergonomics.
Pros - Wholly new design made from the familiar Mark III 2-seater originally designed by ultralight legend Homer Kolb. Widened nose pod makes for a more comfortable aircraft but performance was also enhanced. Distinctive aircraft that will be recognized by most light-sport pilots. Quick-folding wings and tail have long been Kolb strong points.
Cons - Character has changed with the wider nose and flaperons replacing discreet flaps; aircraft flies faster. With Rotax 912 engine, price rises beyond $25,000. Builders have often said Kolb designs are quite labor-intensive.
Subsystems available to pilot such as: Flaps; Fuel sources; Electric start; In-air restart; Brakes; Engine controls; Navigations; Radio; (items covered may be optional).
Pros - Dual throttles are a great replacement to the center throttle; no more reaching across. Trim is easily used (by left-seat occupant only) and secure as to position with detents. Choke is handy just to the right of the pilot's head; can be reached by either occupant. Powerful hydraulic brakes installed in test Xtra.
Cons - Trim cannot be reached by the right-seat occupant. No easy way to determine fuel in flight (unless gauges installed by builder). Hydraulic toe brakes are optional (though they are differential and use nice hardware). Flaperon handle is rather far aft and is somewhat awkward to reach.
Instrumentation; Ergonomics of controls; Creature comforts; (items covered may be optional).
Pros - Major improvement to cockpit with the wider nose; your legs no longer have to angle to the center. Much more open inside with enormous visibility. Seats are well padded, not just Kolb's once common sling-type seat. Four-point seat belts were installed in tested Xtra. Full enclosure effectively blocked windblast.
Cons - Fuel tanks have to be filled inside the aircraft; fumes result (though the aft of the cabin is open and fumes are pulled out when the engine starts). Doors restrained by chains, as on test Xtra, don't open far enough for the easiest entry. Open aft cabin makes for a noisier environment.
Taxi visibility; Steering; Turn radius; Shock absorption; Stance/Stability; Braking.
Pros - Though the Xtra sits low, it still has good ground clearance, and prop is protected by main tail boom. Wide-open visibility is a real plus before takeoff. Full-swiveling tailwheel makes for tight turning capability. Directional hydraulic brakes assured good ramp maneuverability and offered substantial stopping power.
Cons - All Kolbs tend to have a noisy cable "slap" as they are routed inside the tail boom; no problems reported but sound can be distracting if you hear it over your ear protection. Suspension is limited to gear leg flex. If gear leg is damaged, labor is significant for replacement according to factory workers.
Qualities; Efficiency; Ease; Comparative values.
Pros - Great launch enthusiasm comes with the 81-hp Rotax 912 engine. Ground break is well under 200 feet. Visibility out of the helicopter-like cockpit is huge; very helpful for landing at crowded airports. Excellent crosswind control capability.
Cons - Heavier airplane (with 912) makes for slightly longer landing roll (though still only about 250 feet). At its weight with the big engine, landing with a little power seems to help a lot. Design tends to lose energy quickly in ground effect; be ready for the round-out phase.
Quality and quantity for: Coordination; Authority; Pressures; Response; and Coupling.
Pros - Handling has always been a strong point of Kolb designs; still great in crosswinds or rowdy air. Control harmony is quite good (though see negative). The Xtra was easy to control in formation with photo plane. Adverse yaw is less than many designs. The Xtra's somewhat heavier flaperons may give some pilots the feedback they want.
Cons - Flaperons are on the stiff side (even according to New Kolb's owner). This also suggests control harmony cannot be as good as the older models. While the deck angle is very shallow, the Xtra is still a taildragger and some pilots don't feel ready for such gear.
Climb; Glide; Sink; Cruise/stall/max speeds; Endurance; Range; Maneuverability.
Pros - The 81-hp Rotax 912 assures excellent performance even at full gross (tested well below). Cruises easily at 75 mph and can hold 90 mph, quite a bit faster than older Mark IIIs. Climb is more than 1,000 fpm. Performance with 65-hp Rotax 582 is also quite strong. Good payload; can nearly carry its empty weight in occupants.
Cons - Not everyone is seeking higher speed (though those buyers can select the Rotax 582 while saving around $6,000). The Xtra with the big 4-stroke, 4-cylinder engine becomes a heavier plane that loses some of the agility long associated with more minimalist Kolb designs.
Stall recovery and characteristics; Dampening; Spiral stability; Adverse yaw qualities.
Pros - Secure seat restraint was appreciated, as was the BRS parachute system installed in the wing cavity with pull handle in aft of cabin. Stalls were reasonably slow, at around 40 mph. Stall responses were normal and uneventful. Controls remain effective right down to stall break; allows slower speed approaches.
Cons - Power-on stalls put the Xtra at a very high deck angle; it will surprise most new Mark III pilots. A parachute handle you have to turn to reach might not be optimal in a violent upset situation. With the higher thrust line, added power will push the nose over slightly (though backing off slightly stops this).
Addresses the questions: "Will a buyer get what he/she expects to buy, and did the designer/builder achieve the chosen goal?"
Pros - Proven design with years of history in the ultralight arena and many aircraft flying successfully. Redesign by Barnaby Wainfan comes with many extras (as its name implies). Company offers quick-build options for those who want to get in the air faster. Once-new ownership is now well established and has continued the solid reputation of Homer Kolb's original company.
Cons - Most Kolb designs are considered rather build-intensive; company estimates 500+ hours to complete the Xtra (though optional quick-build kit can lower this substantially). Priced with 81-hp Rotax 912 engine, the Xtra will run more than $25,000 before owner customization or more options. Taildraggers aren't for everyone, which may affect resale.