For ultralight enthusiasts, the focus of this pilot report is on the Kolbra model that I flew in late summer 2000, fitted with the 66-hp Rotax 582. A King Kolbra version is also available, but because it is equipped with the 80-hp 4-stroke, 4-cylinder Jabiru engine, it cannot make FAR Part 103 trainer exemption weight limits.
The two new Kolbra offerings give The New Kolb Aircraft Company a better footing in the 2-seat market. Until now, of the five models New Kolb offered for sale, the Mark III was their only 2-seater. Another 2-seater, the low-wing Laser, never made it to market and the outlook appears uncertain for any introduction of that model.
The New Kolb Aircraft Company is clearly focused on 2-seaters. The company released a new version of their popular Mark III, named the Mark III Xtra, in the spring of 2000 and now the Kolbras. Their single-seaters – the FireFly, FireStar, FireStar II (with optional jump seat but no dual controls), and SlingShot – remain unchanged… and that’s a very good thing in my opinion. I like each of those models.
The side-by-side Xtra was a fine job of engineering by aerodynamicist Barnaby Wainfan, who has also done the work on the tandem Kolbra. Side-by-side seating is popular with instructors, but that doesn’t mean everyone loves it. Some folks think tandem seating is the best. The New Kolb Aircraft Company says, “With the student seated in the front, he will feel comfortable with flying solo upon completion of training.” Now equipped with the tandem Kolbra trainer, the Kentucky-based company can serve either interest.
Stretched FireStar II?
Is the Kolbra simply a stretched FireStar II that’s been beefed up? No, but if you take the FireStar II fuselage, stretch it enough to implant full dual controls, give the aft seat a usable amount of room and then add the Mark III tried-and-proven wing, you’d be close to a Kolbra.
Wainfan is a respected engineer who has done some groundbreaking work, including his fascinating Facetmobile. The novel lightweight aircraft has unusual looks and appears designed for stealth operation but it shows the versatility of the designer. The Kolbra is a little more down-to-earth but it brings some changes, like those appearing on the Xtra.
Most notable is the changed nose and the instrument pod. Both reminiscent of the Xtra changes, they yield similar results, offering more foot room, more easily read gauges, and switches that are easier to reach while securely belted. An enlarged cabin with lots of Lexan makes the cabin seem airy. Wainfan considered the cockpit shape to help performance.
Entry to the rear seat will be rather challenging for less able pilots, but once in, you have a seat to yourself. In contrast, a passenger seated in the rear jump seat of the FireStar II may feel like passengers in older tandem trikes, that is, jammed one into the other in a way many don’t find very comfortable. This is not intended as a condemnation of the FireStar II, which otherwise addresses the desire for a second occasional-use seat in a plane that feels more like a single-seater. Even visibility in the Kolbra’s rear seat is better than many tandem ultralights, especially given the overhead skylight treatment.
Where the new comfort really lies is in the front seat, and that’s where I had the privilege to fly.
Two Kolbras are pictured in this pilot report. A red Kolbra ULT (or ultralight trainer) was built by distributor Lite Speed Aviation located about an hour from the New Kolb factory in Stanton, Kentucky. Danny Mullins, the proprietor of Lite Speed, is the man who built the red Kolbra that I flew. Mullins and team did a wonderful job, and report it took 50 days to create the red ultralight.
The beautifully appointed orange-and-blue model was fitted with the 80-hp Jabiru and was built by the factory as an example of the King Kolbra.
The newer version red Kolbra uses the instrument pod that was first used on the Xtra, which debuted in April 2000. Our evaluation Kolbra also has a nose resembling the Xtra in that it is wider and has a “fold” running left to right. The factory-built King Kolbra uses the older hemispherical shaped nose. Factory airshow representative Issac Therrian reports that people coming to the company’s display say they liked the looks of the older Kolb nose but liked the width of the new style. So he says it is possible the factory will combine the two shapes somewhat in a subsequent model.
The factory-built model had a small instrument console in front of the pilot, but this contained only switches. The rest of the instruments were located more conventionally in a nose pod flange where they are harder to read and reach.
Full dual controls were available front and rear in the Kolbra ULT, although brakes had not yet been connected to the toe levers in the aft seat. This is a change from both the 1+1 configuration used on the FireStar II and SlingShot where a jump seat is available for passenger-carrying duties rather than instruction (which requires FAA registration and an FAA pilot’s certificate).
Although they plan to add it, the factory omitted in-flight trim from our test Kolbra in the effort to stay with Part 103 trainer exemption weight limits. Indeed, the aircraft is said to weigh 495 pounds. In the future, New Kolb Aircraft Company’s president Norm Labhart says they plan to include in-flight trim because they feel they can shave pounds elsewhere as they enter production. With the same expected weight economy, they also expect to add flaperons; our test Kolbra had none.
The throttle was conveniently located to the left of the pilot with a choke handle mounted underneath it (choke goes forward for off, and back for on, though it was not labeled).
When New Kolb adds in-flight trim, the handle will be located down and aft from the throttle. This location could become rather busy as the rear seat occupant’s rudder pedals are alongside the front seat pilot’s hip.
Labhart likes to use a yaw string taped to the windscreen. He says some take this off but he puts it back on, an attitude I share since I also like this simple but highly effective “instrument.”
New Cabin Environment
You fold the front seat backrest forward to permit rear entry and exit. Suggested entry is to face away from the Kolbra and hook one heel in the small stirrup provided alongside the front seat on the ultralight’s right exterior, and ease backwards into the aircraft. The King Kolbra used a version of Cessna’s gear leg step but the entry method remains the same.
Once you’ve lifted yourself up into the Kolbra, you slide rearward into the aft seat, then pull the seat rest back along with your joystick. Most pilots will accomplish this easily enough and since it will often be an experienced instructor in the rear, he or she should have the technique figured out well.
Entry to the front seat is easier, though similar. After entering backward onto the seat, you’ll pull your left leg up and over the joystick and instrument pod. Some less flexible pilots may struggle with this.
The Kolbra has a solid floorboard with the instrument pod mounted to it. You can put substantial weight on the floor, New Kolb reps say, useful during entry and at other times. In the front seat the floorboard covers everything; in the rear, floorboarding is only along the sides. Both seats have a shoulder belt system, which most pilots will appreciate.
The Kolbra was definitely quieter than the Rotax 912-powered Mark III I flew in 1999. In the past I have complained about the noise in some Kolb models. It is Therrian’s opinion that this comes from the gearbox more than any other source – an interesting theory.
Lite Speed had equipped our test Kolbra with hydraulic brakes. They were toe brakes and a little weak but Labhart says this is because they are new and that the brakes improve with usage.
With the 66-hp Rotax 582 accelerating us smartly, we rotated at 60 mph to accommodate strong right crosswinds. For the same reasons, we approached at between 55 and 60 mph in the gusty conditions. However, it was my observation that the faster speed of 60 mph was more effective to ensure a wide flare window even if the wind hadn’t been so strong. This may qualify as a bit fast for an ultralight trainer.
A new mixer for the rudder pedal linkage, located under the forward seat, helps to take up some slack, which improves control harmony. This also tended to reduce the tail boom cable slap that has long identified Kolb designs.
The test Kolbra has a wing loading of 5.2 pounds per square foot, according to Labhart. This can only be true if our test Kolbra weighed 811 pounds fully loaded and perhaps it did as Norm is smaller than I and I’m an FAA average 170 pounds. Not every ultralight flies at its gross weight (though that is more common than having excess, unused weight). At full gross, wing loading calculates to 6.4 pounds per square foot in the Kolbra.
You may find it interesting that most 2-seat ultralights run wing loadings from the high 5s up to 6, 7, 8, and even 9 pounds per square foot. On the other hand, even when built by the same manufacturer most single-place ultralights have wing loadings in the 3- to 4-pound range with the highest hitting the low 5 pounds per square foot. This is true for New Kolb with the FireFly at 4.3 and the FireStar I at 3.9 pounds per square foot. I think this simple fact identifies one of the reasons why single- and 2-seaters fly differently.
Even at 6.4, Kolbra is in the lower range of all ultralight 2-seaters. Putting it in perspective, the flashy new Cirrus SR20 (4-seat general aviation plane) has a wing loading above 20 and hang gliders vary around 2 pounds per square foot.
When you load up the wing more, you generally get greater speed. All other things being roughly equal, handling may be crisper, and stall usually rises. The Kolbra has a 40-mph stall listed in company literature.
The bright red Kolbra had two 5-gallon gas tanks, a Rotax B gearbox plus a 2-blade Warp Drive prop. Several other options are available.
When the owners of The New Kolb Aircraft Company bought the company from Dennis Souder and partners in 1999, they got a batch of designs that have proven themselves over the long haul in ultralight aviation. As they made changes to the Mark III (Xtra) and created the Kolbra tandem models, they’ve been careful not to upset that good reputation.
I saw the Kolbra stall speed at about 45 mph but of course, this is dependent on the accuracy of the installed airspeed indicator and my stall technique. During power-on stalls, the plane never broke but I could feel some disturbance at the prop. However, the wings and tail seemed relatively unaware of power-on stall.
With a conservative entry I executed a power-off stall and the Kolbra did break through, falling slightly to one wing. Successive power-off stalls consistently broke straightforward even though I became more aggressive with the controls.
With its tandem seating, Kolbra can accommodate larger occupants and some instructors do prefer front-and-rear seating to side-by-side. Having your own Kolbra trainer will set you back a shade over $16,000 complete with all airframe kits, a Rotax 582 engine and mount package. At this price, Kolbra has competition, but the Kolb brand name remains very strong and the new company is proving its attitude about improvements and customer service.
If you aren’t in the market for a trainer, the King Kolbra may interest you more. Of course, you must back that interest with more cash, spending more than $20,000 for all airframe kits, the Jabiru engine and its mount package. This is hardly pocket change for most of us, but you will end up with a 4-stroke 4-cylinder ultralight-like aircraft that should deliver the famous Kolb experience.
Exchanging the test Kolbra’s tundra tires for more conventional (smaller, lighter) tires, by removing radio equipment not needed in the training environment, and by using a more modest paint job, flaperons and in-flight trim can be added while still staying within the exemption weight, says Labhart. Put all this together and I think The New Kolb Aircraft Company has a winner in the ultralight training market.
|Empty weight||495 pounds|
|Gross weight||1,000 pounds|
|Wing area||156 square feet|
|Wing loading||6.4 pounds per square foot|
|Length||24 feet (same with folded wings)|
|Build time||400 hours (est.)|
|Notes:||1Quick-build and fully assembled options are available through the company or third parties.|
|Standard engine||Rotax 582|
|Power||66 hp at 6,500 rpm|
|Power loading||15.2 pounds per hp|
|Cruise speed||(75% power) 75 mph|
|Never exceed speed||110 mph|
|Rate of climb at gross||750 fpm|
|Takeoff distance at gross||250 feet|
|Landing distance at gross||350 feet|
|Standard Features||Tandem 2-seater, 66-hp Rotax 582 with B gearbox and 2-blade prop, fully enclosed cabin (rear windows open), folding wings, fiberglass nose fairing, broad Lexan windows and skylight, streamlined struts, full dual controls, two 5-gallon fuel tanks.|
|Options||Hydraulic brakes, engines up to 80-hp Jabiru (King Kolbra model), electric starter, 3-blade prop, instruments and EIS engine system, quick build and assembly options, ballistic parachute, upholstery package.|
|Construction||Aluminum wings and tail boom, welded steel fuselage and tail structure, fiberglass fairing, Stits dope-and-fabric wing coverings, Lexan windows.|
Cosmetic appearance, structural integrity, achievement of design goals, effectiveness of aerodynamics, ergonomics.
Pros – As with their 2-seat Xtra, Kolbra is a new design for The New Kolb Aircraft Company. Offered to training market; can pass Part 103 exemption weight rule with careful building. New owners are doing well with an old name, developing 2-seaters with outside expertise and maintaining the popular single-seaters. Tandem Kolbra has large interior and better rear-seat visibility than many tandem ultralights.
Cons – Some prefer tandem, it’s true, but many instructors prefer side-by-side (fortunately they can choose the company’s also-new Xtra). As taildraggers go this one is easy enough but many buyers simply don’t feel comfortable with them, preferring tri-gear. Build time is higher than many ultralight designs; quick-build option is available but naturally raises the price.
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 – Simplified Kolbra made for ultralight training use has no flaps yet (flaperons are planned), no trim (also coming), and full dual controls. King Kolbra model can have more systems if FAA-registered. Builder Lite Speed found a couple agreeable spaces for radio and GPS. Easily accessed choke. Electric starting always spoils pilots in a way they like. Easy engine access for maintenance.
Cons – Gone are the barn-door-sized flaps of the Xtra and earlier Mark IIIs. Trim is needed in training environments; New Kolb has the option but it was left off to save weight. With some twisting, the instructor may be able to see fuel quantity. No explanatory labels yet added, for example, showing choke positions.
Instrumentation; Ergonomics of controls; Creature comforts; (items covered may be optional).
Pros – Wonderful new job on the Kolbra’s nose (as with the Xtra); gives more foot room, a modern look, and much easier gauge reading and switch access (thanks to instrument pod mount). For tandem lovers, this is a job well done. Both display Kolbras were beautifully finished inside and out. Four-point seat belts at both seats will be widely appreciated. Full enclosure will delight northern pilots. Less noisy than Mark III. Floorboard can take weight well.
Cons – No brakes were installed in the rear, where the instructor will often sit. Entry process, especially to rear, will rule out some less flexible pilots (front seat is much easier). No cargo area and little room for stash containers. No simple seat or pedal adjustment for different size occupants. Not all buyers desire full enclosure.
Taxi visibility; Steering; Turn radius; Shock absorption; Stance/Stability; Braking.
Pros – Visibility, always good in Kolbs, is broad even in the rear seat (unusual among many tandem ultralights). Test Kolbra (built by Lite Speed) has shiny hydraulic brakes that appeared to be reasonably lightweight. Tailwheel steering is quite good; swivels fully for easy hand maneuvering. Generous ground clearance.
Cons – With stall at 40 mph, approaches must be done at 50 mph or more (some ultralight trainers are slower). Suspension is limited to air in the tires and gear leg flex. Tailwheel maneuvering isn’t as natural to pilots trained in tri-gear ultralights. Brakes were a bit weak but factory attributes this to newness and says they improve with use.
Qualities; Efficiency; Ease; Comparative values.
Pros – Standard 66-hp Rotax 582 accelerates strongly. Potent climb ability listed at 750 fpm at full gross; 1,000 if flown solo. Visibility during takeoff or landing operations is huge; even the rear tandem seat is acceptable (many are quite limited). Crosswind capability is very good thanks to crisp, fluid controls. Landing energy retention is better than older Mark III.
Cons – Used 60 mph rotation and approach speed in gusty conditions; extends landing distance and could limit short-field operations (remember, no flaps and the brakes were weak). Compared to slower flying New Kolb single-place models, Kolbra will require somewhat more experience for good takeoffs and landings.
Quality and quantity for: Coordination; Authority; Pressures; Response; and Coupling.
Pros – Control range in new cockpit has no space limitations. Classic Kolb-brand handling; light and responsive without being overly sensitive. Adverse yaw is much better than the more highly loaded SlingShot; half-span ailerons appeared well harmonized. Ailerons massed balanced at tip to reduce flutter likelihood. Crosswind capability limited only by pilot skill as controls have good authority at all speeds.
Cons – It’s hard to fault Kolb handling and the same is true on this Kolbra. About the only negative I can offer is that the handling may be too responsive for some less experienced pilots.
Climb; Glide; Sink; Cruise/stall/max speeds; Endurance; Range; Maneuverability.
Pros – Climb plus cruise (at 75 mph) are both improved on the Kolbra 66-hp 582 over the older Mark III version. With 80-hp Jabiru engine, the King Kolbra (N-numbers required) is faster at 85-mph cruise. Sink rate performance was quite good perhaps showing the value of lower-drag tandem seating configuration. Slow flight qualities in the 50s are quite good.
Cons – Despite speed increases, Kolbs remain an average- to slower-flying ultralight (though, personally, I think this is a good thing). Cruise is listed at 68% of Vne, less for example, than on the Thunder Gull line at better than 80%. King Kolbra performance costs more ($20,000 or more for kit and engine package, a $4,000+ premium over regular Kolbra).
Stall recovery and characteristics; Dampening; Spiral stability; Adverse yaw qualities.
Pros – Stalls have always been and remain mild affairs on Kolb wings, which work hard. Power-on stalls basically never happen though nose angle becomes very high. Controls remain effective to very low speeds. Uses same basic wing construction as on Mark III, a very well proven and stout wing, which provides a solid feel in the air. Tail surfaces were reportedly enlarged to gain enhanced control at lower speeds.
Cons – Stall listed at 40 mph (45 on King Kolbra) and I did not see numbers this low though installed ASI error might be the culprit. High thrust line pushes nose over slightly on power-up. Lack of trim on test plane made some longitudinal stability verifications impossible.
Addresses the questions: “Will a buyer get what he/she expects to buy, and did the designer/builder achieve the chosen goal?”
Pros – The New Kolb Aircraft Company is alive with work and developments – the Kolbra is the latest example of these improvements. New CEO, Norm Labhart, is a capable man and genuine flying enthusiast. The old company’s in good hands and this should make potential buyers feel good. Brute wing main spar and tail boom. Popular folding wings remain. Kolb designs have been flying successfully for many years.
Cons – Unless you choose the quick-build option or a fully built exemption trainer, build times are among the longest in ultralight aviation (contact New Kolb for options on building). At $16,000+ Kolbra isn’t the low cost kit its predecessors were; King Kolbra goes over $20,000. No tri-gear choices in entire company line. Some instructors will prefer side-by-side (though they can always choose the New Kolb Mark III Xtra).