As with many ultralight aircraft brands, when single-seaters become dual machines the machine gets heavier and more complicated. And when ultralights get heavier, they often don’t work quite the same.
Since flight school operators and pilots wanting to carry a friend request 2-seat capability, ultralight manufacturers respond, trying to get as close as possible to single-seater feel. But this isn’t simple. Two-seat ultralights often give up some of the qualities that make a single-seater pure joy to fly.
However, designers make constant refinements in ultralights.
Look around at airshows. Most of the ultralights on display these days are well-built machines with lots of custom hardware. Nearly every one got that good employing the CANI approach – Constant And Never-ending Improvement.
Golden Circle’s T-Bird II is one model that has seen subtle but noticeable improvements that make the breed better. Even to those intimate with the Iowa ultralight producer, these changes may evade your inspection.
Changes in the Wind
The most effective alteration made by Golden Circle involves the wing rib profiles. Boss Bob Ellefson and associate Mike Knorr realized that as they installed fabric tightly and then applied heat for some further shrinking, two things happened: The wing fabric got smoother but at a price.
The tightened fabric also tugged downwards on the ribs inserted into the upper surface pockets. From the wing’s high point a few inches aft of the leading edge, the ribs tended to assume a concave shape. Ellefson and Knorr believed this caused some disturbance to the airflow, a fact I can corroborate from years of watching changes to the wing rib profiles on hang gliders. Those glider designers are obsessed with making the smoothest, most efficient wing possible and they discovered something similar about rib deflection when they continually tightened the wing skin.
Ellefson and Knorr went through a time-honored process of trial and error, reshaping wing ribs slightly and then going flying to see what they had accomplished. Over a period of two months, the pair of tinkers found an optimal shape. The ribs were given some extra curvature that resulted in a straighter line from the rib’s high point, or apex, to the trailing edge. Turbulent air flow was reduced and two beneficial characteristics resulted.
“We found a smoother airflow aft of the apex both slowed stall speed and increased top speed,” reports Ellefson. Though these two facts seem somewhat at odds, I have heard a similar description from hang glider designers and other Dacron-wing ultralight producers. The question is finding that ideal profile. In certified aircraft design, these investigations are highly evolved and an engineer with the right computer-aided design (CAD) program can devise a precise shape. In hang glider or ultralight design, art may be greater than science and trial-and-error designing is not only more effective, it’s affordable. High-end CAD research and development programs run by aeronautical engineers cost more than most ultralight producers can think of spending.
Ellefson and Knorr are now inspired to try vortex generators on the wing in an attempt to lower the stall speed even further. And again, I’ve seen this work on aircraft as disparate as hang gliders and Learjets, so it seems possible this could bring the desired results for Golden Circle. Ellefson believes the already-improved stall speed can be brought down to the low 30s even with two on board, a worthwhile goal for any ultralight.
The effect of the wing rib profile adjustment – when combined with the optional tri-gear configuration – dramatically changed my mind about the T-Bird II. I’ve been openly negative about the T-Bird in the past, not caring for it in a taildragger configuration and its common fitting of tundra tires. I found the old versions took an increase of speed on final approach (in order to retain adequate energy for rounding out to touchdown), and those darn tundra tires tended to bounce me back in the air if I didn’t have the airspeed dialed in precisely.
After landing the redesigned T-Bird II tri-gear model, Ultralight Flying! editor in chief Scott Wilcox remembers me being impressed. We discussed this because he knew I had not been a fan of the older 2- seater from Golden Circle. (This is quite different from their single-seater, which I’ve enjoyed as much as any ultralight I’ve ever flown.)
Despite the time I’ve been around ultralight designers and heard their philosophies about change, merely reshaping the ribs didn’t likely make this much difference. Of course, ribs impart the wing’s shape in an ultralight like the T-Bird II and that shape is obviously important.
I’m also fairly sure – though I can’t say from actual experience – that the taildragger T-Bird II would also be helped by this change. Since I like taildraggers, I might now like that model with the wing rib adjustment. Yet for many pilots already unsure of their ability with taildraggers, the redesigned tri-gear T-Bird II is much more highly recommended than in the past.
On the downside, I still hear of builders who are uncertain about weight and balance in 2-place T-Birds. I certainly believe that all ultralights should be very carefully examined to assure weight and balance is within design specifications. Whether you choose Golden Circle or another manufacturer, ask to be sure you’re doing this part right. It can make all the difference in the world!
Since my last flight in a T-Bird II, the company made few other changes. However, Ellefson claims that optional streamlined struts add 7 mph to the top end. “Cruise is now 72 versus 65 earlier,” he says. Also, the root tube on this bigger T-Bird went from aluminum to chromoly steel.
Weight and Wing Area
In addition to the new qualities of the T-Bird II, the design relies on an old dependable method of staying ultralight-like. Though it’s true the 500-pound-plus tricycle T-Bird II (481 pounds in taildragger configuration) isn’t the lightest bird in the flock of 2-seat ultralights, it retains the genre’s flight qualities quite faithfully. How it achieves this is partly due to loading.
Wing loading is only 5.3 pounds per square foot (6 to 8 is a common range for many 2-seat ultralights, though a few come in even lower than the T-Bird). The lightly loaded approach came from original designer Dale Kjellsen. At 190 square feet of wing, the T-Bird has more area than many ultralight 2-seaters. Of course, wing area isn’t the only parameter useful to understand wing efficiency. Other factors include camber height, undercamber, aspect ratio, leading edge profile, and construction technique and materials.
At the time the first T-Birds were hatched (they were called Tierras then), Kjellsen was emulating market leader Quicksilver, whose MX wing descended from hang gliders which used a larger-area, lighter wing loading philosophy. When Golden Circle bought the designs from Kjellsen, they stuck with the large wing.
In other 2-seat ultralight developments, many employed higher wing loadings to achieve better cruise speeds and crisper handling. This is a valid way to refine a 2-seater, but it makes it less ultralight in its basic feel. Approach and stall speeds get higher, the minimum landing area stretches out, fuel consumption goes up, and the landscape zooms by underneath, relinquishing the leisurely pace of ultralight sightseeing to gain faster cross-country flying.
T-Birds – both the single- and 2-place models – have remained true to the ultralight operational envelope.
Get In and Fly
Entering either seat of the T-Bird II requires stepping around the control wheel and angling back into the seat. Take care that your toe doesn’t catch on the yoke handle. Joystick-equipped T-Birds require a similar entry technique.
Once seated, I wasn’t sure I liked the deeply reclined seat posture, though like so much of the T-Bird heritage, this quality is similar to a Quicksilver or Kolb.
T-Birds also show an ability to handle larger-sized pilots. Many ultralight designs are deficient in this area. Unfortunately, designers often build planes to their own body and a number of these fellows don’t measure up to FAA’s 175-pound pilot. To extract more performance or to save weight, they squeeze all nonessential space to a minimum. This drives accessory makers crazy as no space is left for after-market products. Also ignored are owners who are bigger than the designer.
No problem with any of the T-Birds. Maybe because Golden Circle president Bob Ellefson is a tall man, their ultralights will accommodate tall or wide pilots with more comfort than many ultralights. On their single-place T-Bird, Golden Circle is unusual by offering an enlarged cabin for $350. The 2-seat T-Bird II doesn’t need this cabin extension as it is already roomy and has adjustable rudder pedals that “will easily accommodate a 6-foot, 7-inch pilot,” says Ellefson.
My only complaint about the cabin environment was that our test T-Bird II lacked shoulder belts. Lap belts aren’t enough and since Golden Circle offers shoulder belts as an option, I’d sure appreciate it if they’d install them as standard equipment.
No T-Bird has flaps. Ellefson says since the T-Birds land so slowly anyway, flaps aren’t necessary although he’s aware some pilots want them regardless.
With other cabin controls, I found access to be well-designed. The throttle and trim controls are nice pieces of hardware and are mounted between the seats where either occupant can reach them comfortably.
A brake handle is located overhead. Someone told me he thought this was a dumb place for this control but I found it very useful because when you pull against your body weight (and tight seat belts), you get a great deal of leverage from this location. Golden Circle uses a hydraulic system that was reasonably effective at braking the T-Bird II.
About my only complaint of the trim and throttle is that they are located quite close to one another, and are similar in shape and feel. Therefore you might fumble briefly with the trim lever thinking you’ve grabbed the throttle and this could cause a problem. However, a builder could install a rubber grip over one or the other to help identify them by tactile sensation. (Look inside a general aviation airplane and you’ll see the throttle, carburetor heat, and mixture controls all have unique shapes. This allows you to tell which you’ve got in your hand, even though they are placed adjacent to one another.)
Ground handling the tri-gear T-Bird II is very good. The nosewheel is very steerable and offers a tight turn radius (although a full-swiveling tailwheel can produce even tighter maneuvers). Nosewheel suspension was quite good; it really absorbed the bumps well. I’ve also found all the T-Birds very stable on their steel gear and the tri-gear is the best of their line in this regard.
Pleasant Ups and Downs
Takeoff in the tri-gear T-Bird II is superior to those of the taildragging 2-seater, in my opinion. It isn’t the “piece of cake” process I love in their single-seater, but it’s basic enough that even new pilots should find little challenge. Add power, wait a short while as the 66-hp Rotax 582 engine accelerates you, and pull the yoke liberally aft. Relax the yoke gradually, guard your speed, and fly away. The process is sufficiently typical of many aircraft that prior experience will be helpful.
Approaching to land at 55 mph in the redesigned T-Bird II, I found a big difference from the earlier model. In the older models, after flying around at 60 mph, I learned to speed up slightly on approach. Certainly this was true if I’d slowed to the 50s, and the effect wasn’t intuitive as most pilots expect to slow from cruise to approach. If you did so on the earlier T-Bird II, you’d probably bounce the landing as you’d burn off all the energy prematurely and would stall or mush onto the surface. Now with the improved wing I found the speed-up technique was no longer required and the T-Bird II retained its energy much better. While it’s hard to be quantitative with years in-between experience, I have no doubt whatsoever that the redesigned T-Birds are superior.
In flight I didn’t notice the steep seat back angle. I had expected visibility would be obstructed when seated back because of the cockpit structural tubing surrounding me. However, vision was broad thanks to the ample use of clear plastic in the cockpit enclosure. I’ve also found all T-Birds also offer great lateral visibility as you sit right at the leading edge.
A lot of plastic is also used in the nose enclosure, a design trait Golden Circle shares with RANS ultralight models (or maybe that’s the other way around, since Golden Circle had it first). On a warm sunny day in Florida, the sun room effect cooked my feet. The solution was simple enough, as the T-Bird had no doors: I pulled my legs back and then could put my feet out in the wind. Yet the experience showed that with the optional doors, a northern pilot can expect reasonably adequate protection for winter flying.
The T-Bird II has 190 square feet of wing. Not only does this produce a lighter wing loading as previously discussed, but added to the wing rib reshaping, the model gains interesting performance qualities.
Descent rate proved to be a fairly modest 500 fpm while I flew solo. Naturally, this will increase with extra weight but perhaps not as much as you’d think. No matter the exact figure – instrument plus human error suggest my estimate is imperfect – the revised T-Bird II wing again showed itself better than the older models. Many 2-seat ultralights descend faster, some upwards of 600-800 fpm.
One part that still throws me is that climb rate is not as strong as expected. Given the improved wing that I’d noticed in other flight regimes, I expected climb to be better. Flying solo, the Rotax 582 boosted me about 700-750 fpm, which isn’t bad, but Golden Circle reports the number is 600 fpm when flying at gross. I have no explanation for this softer climb performance since engine-idle descent was as good as it was.
No one is likely to call the T-Bird II a hot performer. With its one-time Quicksilver design heritage, don’t expect the T-Bird models to fly exceptionally fast nor do radical maneuvers.
Yet you shouldn’t take this as a criticism. All T-Birds do very well at the type of flying ultralight pilots like very much: low and slow.
The redesigned T-Bird II offered lower speeds and stalls, good handling at those slower speeds, and an easy-flying nature.
Maneuvering liberally for greater experience, I found the control wheel linked to push-rods brought exceptional smoothness. A yoke doesn’t lean from side to side thereby yielding more lateral room in the cockpit, whereas joysticks often hit your leg on full deflection.
Roll control is not fast in a T-Bird II, though four seconds in 45-to-45 reversing is certainly adequate for most crosswind landings. Steep turns were surprisingly solid, though I ran out of range if I banked steeply without adding nearly full power.
T-Bird controls balance fairly well, that is, rudder and ailerons have reasonably balanced authority. The combination of roll rate, harmony, and ease of control pressure made my Dutch rolls work quite well. I could not sustain them to higher banks, but that’s expected in an ultralight that exhibits moderate roll rates.
T-Bird II’s big wing and revised profile help bring lower stall speeds, down into the mid-30s. I recalled – and Ellefson concurred – that the older models were closer to 40 mph in power-off stalls. Cutting 5 mph off the stall speed in a big 2-seater like this is a noteworthy achievement. I never know for sure how accurate an ASI is, but it read 35-37 mph in most stalls I performed. What will be interesting to see is if Ellefson and Knorr can nudge that figure down to the low 30s by vortex generators that may be installed later this year.
Besides the hard numbers, my series of stalls in the redesigned T-Bird II made me aware of those wing rib changes. Power-off stalls seemed to have less sharpness to the break, though those sensations are tough to quantify. T-Birds have long benefited from their high-camber wings and the new wing profile seems to complement the thickness. Power-on stalls produced a mushing climb.
I was unable to create a breaking accelerated stall, partly due to insufficient back yoke range. Accelerated stalls in the new T-Bird II wallowed like they might fall to the outside wing, but I never experienced this in several attempts.
Aircraft Super-Market Shopping
Golden Circle has an unusually long list of optional items you can put on your own T-Bird II (of course, all the weight you add comes with some flight penalties, as with most ultralights). Rather than go through them all, I’ll leave it to those especially interested to ring up Golden Circle’s Aircraft Super-Market and ask for details.
But you have two very interesting choices that bear mentioning.
Golden Circle ultralights come stock with a control yoke. Like many others I prefer a joystick and this presents no problem as Golden Circle offers a joystick for those who want one. It also doesn’t matter if you’re hesitant about taildraggers as Golden Circle also offers either tri-gear or taildragger (the tri-gear is a $920 option, and is worth considering, in my opinion).
For years T-Bird has offered eye-catching, brightly-colored airframes and wing covering that employ Mylarized laminates that look slick and clean easily. Frames are powder coated and you can order several colors of sails. A brilliant colored ultralight like the T-Bird II looks friendly and fun, which can’t hurt sales.
You can visit Golden Circle at an airshow or at their huge facility alongside the freeway just west of Des Moines, Iowa. Seek out owners Bob or Dorly Ellefson and see for yourself if the colorful T-Bird II is your ultralight.
|Empty weight||481 pounds1|
|Gross weight||1,000 pounds|
|Wing area||190 square feet|
|Wing loading||5.23 pounds per square foot|
|Build time||40-60 hours|
|Notes:||1Tri-gear setup reviewed in this article adds 30 pounds; costs $920.|
|Standard engine||Rotax 582|
|Power||66 hp at 6,500 rpm|
|Power loading||15.15 pounds per horsepower|
|Cruise speed||68 mph|
|Never exceed speed||95 mph|
|Rate of climb at gross||600 fpm|
|Takeoff distance at gross||300 feet|
|Landing distance at gross||250 feet|
|Standard Features||Side-by-side seating in taildragger configuration, strut-braced wings, nosewheel steering, airspeed indicator, tachometer, water temperature, cockpit enclosure (full except doors which are optional), 12-gallon fuel tank, Dacron® wing covers with no painting required, engine mount for Rotax.|
|Options||75-hp Rotax 618 or 80-hp 912 or Wankel rotary engine, tricycle gear, electric starting, streamlined struts, swing-up doors, cabin heat, hydraulic brakes, tundra tires, wheel pants, amphibious floats, additional instruments, intercom, strobe light, shoulder belts, ballistic parachute, 2- or 3-blade composite prop, agriculture spraying apparatus, quick-build kit (30-42 hours, according to factory).|
|Construction||Aluminum tubing, welded steel, Dacron® sailcloth with Mylar® finish.|
Cosmetic appearance, structural integrity, achievement of design goals, effectiveness of aerodynamics, ergonomics.
Pros – Tried-and-true shape that lends itself to ultralight flying. In my opinion the tri-gear T-Bird II is superior to the taildragger. New wing rib shaping yielded better flight characteristics. Golden Circle has long used brightly-colored airframes and Mylar-coated wing coverings to earn good first impressions.
Cons – Being well-rounded means the T-Bird does not stand out in a particular category. Design tends to run heavy for the load it carries. Taildragger model is quite tail heavy on the ground.
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 – Our test T-Bird II was equipped with brakes, in-flight-adjustable trim, electric starting. Primer and kill switches conveniently located overhead, and are not easily bumped. Plenty of interior room for tube-mounted radios or GPS units. Engine access is wide open.
Cons – Tri-gear T-Bird II requires N-numbers and FAA registration (though this means you can add systems without weight concerns). Panel space on the test T-Bird was limited. No flaps are available on any T-Bird. Brakes were nondirectional (though nosewheel is responsive enough to cancel need).
Instrumentation; Ergonomics of controls; Creature comforts; (items covered may be optional).
Pros – Overhead brake handle gives excellent leverage; system was hydraulic on test ultralight and worked well. Multiple detents on trim let you adjust by feel. Roomy cabin, one of the largest in its class. Full enclosure possible with optional gull-wing doors which attach quickly. Easily ground-adjustable rudder pedals permit a wide range of pilot sizes.
Cons – Test plane seat restraint limited to lap belts, which I consider insufficient. Fuel into the cabin-mounted gas tank adds gas odors to the interior. Angled back seat won’t appeal to everyone. No easy seat adjustments. Your feet can get warm on hot days.
Taxi visibility; Steering; Turn radius; Shock absorption; Stance/Stability; Braking.
Pros – Nosewheel is very cooperative, actually superior to taildragger T-Bird II I’d once flown. Visibility is good in all directions for checking other traffic. Brakes on the test T-Bird were potent and the cabin lever offered excellent leverage. Main gear felt up to rougher runways; taxied stably throughout flight test. Good ground clearance for off-field landings.
Cons – T-Bird II is on the heavy side and taxiing it reveals this (although this can actually be helpful on windy days). Unidirectional brakes don’t aid steering. Turn radius can be tighter with the right tailwheel than possible with nosewheel steering (common to many either-gear designs).
Qualities; Efficiency; Ease; Comparative values.
Pros – Thanks to rib-shaping changes, approaches can be made more slowly and still leave adequate authority for roundout control. Visibility is excellent on both departures and approaches; lateral visibility is also good to assure no traffic conflicts. Control is authoritative enough to permit landings with some crosswind component. Good clearance for rougher runways.
Cons – No flaps made slipping the only tool for controlling approaches (other than good planning and speed control). Tundra or extra-wide tires that Golden Circle likes have bounce-back-into-the-air potential. Approach speed, though better, is still higher than some similar ultralights.
Quality and quantity for: Coordination; Authority; Pressures; Response; and Coupling.
Pros – Yoke control will please many conventionally trained pilots (yokes are standard in general aviation trainers); joystick is optional for those who dislike yokes. Controls exhibit adequate authority for most conditions. Pitch is very stable (assuming you kept weight and balance within specs). No surprises in control actions.
Cons – Full-span ailerons have considerable adverse yaw like many similarly-constructed ultralights. Roll is not very fast on the T-Bird II. Balance between controls isn’t perfect; rudder appears to take somewhat heavier use to coordinate with ailerons.
Climb; Glide; Sink; Cruise/stall/max speeds; Endurance; Range; Maneuverability.
Pros – With its new wing shape, the tri-gear T-Bird II held energy longer. New wing profile provided higher cruise speeds than earlier models, and lower stall speeds, reports the factory. Sink rate and approach glide angle were similarly improved in my attempts.
Cons – Cruise speeds aren’t high on the T-Bird; that isn’t their strength (which is fine with me but maybe not with you). Fuel burn seemed higher than average, possibly explained by the T-Bird’s heavier weight. Climb seemed softer than expected given the new wing efficiency.
Stall recovery and characteristics; Dampening; Spiral stability; Adverse yaw qualities.
Pros – I found no evil characteristics, helping confirm the T-Bird line is good for newer pilots. Stalls were mild breaking and full-power stalls didn’t break at all. Steep turns with liberal power carved smooth turns without a tendency to fall off to one side.
Cons – Full-power stalls wallowed around with high nose angles that felt like they could fall off to one side (though I never experienced this result). I’d much prefer shoulder belts or four-point seat restraint. No spins attempted; no parachute installed. Adverse yaw was significant. Throttle response was negative as it is on most high thrust line pusher ultralights.
Addresses the questions: “Will a buyer get what he/she expects to buy, and did the designer/builder achieve the chosen goal?”
Pros – Golden Circle is a mainstay of the ultralight industry, selling steadily over many years. Comfortable, easy-going style from company, leadership puts buyers at ease during purchase.
Attractively-finished ultralights with bright powder-coated colors. Full enclosure available along with an impressive list of optional choices. New wing profile aids overall handling and performance compared to earlier models.
Cons – Design looks dated to some buyers. Weight-and-balance calculations need improvement, say some owners. Brute strong airframe carries some weight penalty. N-numbers and FAA pilot certificate mandatory with 12-gallon fuel tank and weight beyond 500 pounds empty.