Sleek composite microlight performs like a GA aircraft In the Dec. 11 Flyer, I wrote about the Albatros, which I call a hybrid ultralight because it bridges older tube-and-rag ultralights and new all-composite models.
This month we look at the German-built FK-9 from B&F Technik. A new breed with an interesting history, it too emerged from an earlier design. In fact, the FK-9 shown in photos that accompany this story is the glass-fiber Mark 3. Its predecessors, the Mark 1 and Mark 2, used fabric skins, putting them more in the hybrid category.
To review briefly, hybrid microlights are flying machines that employ the best ideas of familiar ultralight designs, such as sewn Dacron wings and aluminum airframes, yet combine those proven components with composite fuselages and welded steel parts. Simple construction keeps many small builders in business.
Conversely, the composite microlights are typically all-composite designs (or composite over steel) using newer construction technology and techniques. Many are built in former Eastern Bloc countries like Poland and the Czech Republic.
Hybrid performance is generally comparable to other lightweight aircraft, and handling is cooperative. Hybrids excel at short cross-country flights, flying rather low and slow over the countryside. Their advantages include inexpensive prices, less complexity and lower operating costs.
Composites provide better performance, but they also require better flying skills. They can easily make cross-country flights, but they usually cost more than hybrids.
MARK 3’s THE CHARM
I went up in the new Mark 3 version of the FK-9 with Jan (pronounced yawn) Zesewitz, a Toulouse, France-based, German-born distributor of the FK series. He works in marketing for Airbus and uses the same skills for FK sales. In addition to the FK-9, he also represents B&F Technik’s racy biplane, the FK-12 Comet.
Once the two of us were seated, I fiddled with the door latch a bit. The FK-9’s doors open upward, gull-wing style. A tiny but effective latch holds the door up while you enter.
Space inside the cockpit is slightly wider than a Cessna 150. You still touch one another’s shoulder, and big guys may find the FK-9 a bit snug. Europeans are generally leaner than Americans, and the designer may have had the Euro frame in mind with the Mark 3. The aircraft’s door, however, is nicely formed, with an armrest and a hand grip. The closing latch works solidly. For those of average size or a little larger, this microlight offers plenty of interior room, and you can’t quibble with the superb finish of the cockpit.
Both pilots have a left-hand throttle, leaving right hands for the joystick, which is a natural for the majority of right-handed pilots. In the right seat, as with most GA airplanes, one finds no hand or armrest to help with the throttle hand, although the left-side pilot can use the door armrest. Most ergonomic factors of the cockpit appear well considered.
The FK-9 has a nice electronic instrument that offers several pieces of useful information. Take fuel flow. I saw 12 liters per hour, and once trimmed, Zesewitz said it should be 10 liters per hour (2.65 gph, quite a modest burn rate).
The main wheel brakes are operated by a centrally located lever composed of two arms connected by a centered handle. The grip is secure for either pilot, and the brakes are very strong. Good braking is necessary on this particular FK-9 due to a minimum idle of about 2,800 rpm that keeps the airplane moving forward, even on turf.
ABOVE THE ALPS
We launched easily and quickly behind the strong Rotax 912 powerplant. The FK-9’s windscreen has a little motion to it, a weight-saving byproduct of qualifying as a microlight where weight is firmly limited to 450 kilograms (992 pounds). While most of Europe operates under the 450-kilogram gross-weight microlight rule, the FAA does not yet recognize this international standard.
My test FK-9 was fitted with a skylight window, which added to turning visibility considerably even though the opening isn’t as broad as other designs. While seated, you don’t need to lower your head to see laterally (at least at my average height).
Clearly a good bit of effort was made to dampen noise in the cockpit. Indeed, the FK-9 is very quiet. When I took the headsets off, I noticed more wind noise than engine noise in cruise, and the total sound is much less than your average U.S.-built ultralight or light kit. European standards require 55 decibels at full power at about 500 feet AGL. That’s barely above the level of a normal conversation.
One rather surprising omission in such a thoughtfully designed aircraft is the FK-9 Mark 3’s lack of trim. Yet with handling as light as this, trim is almost unnecessary. On landing, for example, I noted almost no muscular effort, even when the stick was held aft.
Zesewitz suggested two notches for takeoff; on landing we used a single notch and approached at 100 kilometers per hour (63 mph). More flaps will lower speed further, but the landing was quite straightforward with a minimal setting and no side slip.
When you engage the flaps, you can access three positions by pushing a button on the lever: minus 10_, plus 5_ and plus 20_ (the minus setting helps increase cruise speed by slightly reflexing the wing). When you activate the flaps, the ailerons automatically droop a bit to aid the effort.
LIGHT AND RESPONSIVE
The FK-9 has light controls that remind me of the Kitfox or Avid airplanes. I also found the controls to be slightly imbalanced, as the rudder is a little more sensitive than the ailerons.
No matter, this is definitely fingertip light flying. I had difficulty keeping the ball centered at first, so it took me a little time to coordinate turns. If the rudders weren’t so sensitive, it would have come quicker.
The FK-9’s roll rate is dashingly quick. Though I did not measure it accurately, I’d guess 45-to-45 roll reversal was about 1.5 seconds, which qualifies as responsive for a consumer aircraft.
Both the ailerons and elevator are mass balanced, with the aileron mass disappearing neatly inside a specially made cavity at the wing tip – yet another example of fine design and workmanship.
After a few series of Dutch-roll coordination exercises, I was able to perform steep turns at 60_ that were straightforward and easy. The FK-9 Mark 3 loves to maneuver and will never wear out its pilot.
Zesewitz told me this test plane is a little under-pitched, so climb was not quite as strong as it might have been. I saw 800 feet per minute on the installed U.S.-made VSI. Indeed, the tach never went above 4,400, though it should be closer to 5,000 rpm, I was told. Naturally that affected cruise a bit, too.
We easily held 160 kilometers per hour (100 mph), somewhat more with full throttle. With the prop in good form, I can see how the FK-9 might reach its claimed top cruise speed of 195 kilometers per hour (122 mph). The factory figure comes at 5,050 rpm.
No break occurred in stalls, even with the stick all the way aft to the seat’s forward edge, and the nose showed no tendency to wander. Overall, the FK-9 feels quite solid, though we also had the benefit of flying in smooth conditions near the lovely High Alps of Southern France.
WANT TO FLY ONE HOME?
The FK-9 has a wing-folding system that one person can manage while standing at the tip. Standard folding wings on the FK-9 generally require a helper, but this option permits one person to move a lever at the wingtip, thus eliminating the need for an assistant. Having first removed some fairing sections from the strut, you can fold the wing aft in minutes.
Is this composite microlight the one for you? As usual, that’s a question that only you can answer.
The hybrid Albatros that I wrote about last month happens to fit my sport-flying desires better than the composite FK-9, though the latter is a lovely airplane I’d be proud to own.
For many Europeans, access to and the cost of general aviation airplanes is prohibitively expensive. Airplanes like the FK-9 fill a need for speedier, more comfortable medium-range cruisers. The Albatros is more a “grown-up” ultralight, with less overall utility than a composite but straightforward handling that allows relaxed aerial sightseeing.
Though the FK-9 evolved from a fairly conventional ultralight, it now represents the leading edge of microlight design. Available ready-to-fly for Europeans, and as a kit for Americans, the FK-9 could find a market in leading sport-aviation countries.
Regardless of your interest, the FK-9 is obviously a fine example of light aircraft that have evolved from the ultralight industry. Its agile flight qualities are proof that the designer did not forget the part about fun.
|Empty weight||572 lbs|
|Gross weight||992 lbs (European Microlight model)|
|Wing area||125 sq ft|
|Cruise speed||120-135 mph|
|Stall Speed (Flaps)||40 mph|
|Rate of climb at gross||1,100 fpm|
|Takeoff distance at gross||395 ft|
|Landing distance at gross||500 ft|
|Range (powered)||(standard tank) 500 mi|
|Notes:||The Mark III model has now been updated to the Mark IV (report to follow).
Fk-9 Mark IV has been approved as a Special Light-Sport Aircraft (11/05)