When a new airplane company pops up on the horizon-something that happens surprisingly often-we pay it the ultimate kindness by doing a flight review and pretending the company will actually be around long enough to build and market the thing.
We don’t like to be a stick in the mud, but the hard reality is that many new launches look good on paper, fly we’ll and may have a terrifically appealing price. But some soon sink without a trace while others stagger along in break-even mode with customers wondering if theyll survive.
Frankly, we had this impression when we first laid eyes on the Diamond Katana, which was introduced in this country from Europe as the Dimona Katana. Yes, it was a nifty and slick plastic design and sure, it flew nicely and looked like the ideal trainer.
It even appeared to have substantial capital behind it which, as we all know, is really what separates survivor airplane companies from the also-rans. Of course, it also suffered the inevitable retraction and round of layoffs due to a slow market and temporary factory over capacity.
But Diamond has hung in and has prospered we’ll enough to have evolved the Katana into two follow-on models, the Eclipse and Evolution. A couple of years ago, it brought out a four-placer, the DA-40 Star.
As with the Katana, the Star has sold well, given the terrible state of the GA economy. As of 2003, Diamond has even entered the personal jet fray with the recently announced D-Jet.
But we digress. This report focuses on the Katana, a sporty little trainer that has all but dominated the new two-seat trainer market.
A New Trainer
When the Katana first appeared in North America in 1994 following its debut in Austria, the market was entering somewhat of a watershed moment. The general economy was strong and GA was showing signs of a modest recovery in the wake of the disastrous sales nosedive in 1978 and 1979. Cessna wasnt back in the market with its piston singles but it was at least talking about re-entry.
The flight school market was more robust than it is now (spring of 2003) and many schools were going great guns in training both foreign and U.S. students for the airline market. Sadly, they didnt have much in the way of new trainers to pick from.
Indeed, the trainer market hobbled along on reworked Cessna 150, 152s and 172s, Piper Warriors and the occasional low-volume upstart, such as the Polish-made Koliber, a rework of the once popular Rallye. Recall too that Piper was just emerging from bankruptcy and wasnt yet up to full speed.
Against this backdrop, the Katana was perfectly positioned and looked-and was-a genuinely new idea, at least for the U.S. market. The company that eventually became Diamond in North America had been building glass aircraft for quite some time.
Hoffman Flugzeughbau formed in 1981 to build the H36 Dimona motor glider in Austria. This product was evolved into follow-on designs including the HK36 and HK36R Super Dimona, which is better known in this country as the Katana Extreme motorglider. Its claimed to be the best selling motorglider in Europe.
In 1989, the company was bought out and renamed HOAC-Austria Flugzeugwerk. Two years later, HOAC was acquired by Diamonds current owners, a family well-established in the automotive business in Europe. Two years later and using the motorglider designs as its foundation, the company began work on the DV20 Katana, the design that has ultimately evolved into the DA20 Katana, the Eclipse and the Evolution.
The DV20 is considered the Austrian Katana and is very similar to the motorglider design but with shorter wings, electric flaps, tricycle rather than conventional landing gear and other minor changes. A total of 160 DV20s were built and although most remained in Europe, some found their way to North America as seed units for what eventually became the DA20 Katana.
While production of the DV20 in Austria went into full swing, the company set up shop in 1992 in London, Ontario in an existing aircraft plant that had manufactured military aircraft during World War II. The intent was to develop a North American version of the Katana. The model was initially known as the Dimona Katana until the company officially changed its name to Diamond Aircraft Industries in 1994.
While it built Katanas in Canada, most of the R & D on new models took place in Austria, at the companys Wiener Neustadt facility.
Diamond has continued that method of work as it develops new models, including the DA40 Star, the diesel-powered DA42 Twin Star and the recently announced D-JET single-engine high-performance personal jet.
All Glass
The first Katanas can be fairly described as Eurosleek, with a modern, streamlined planform and a distinctly motorglider look. Although Diamond has improved and tweaked the basic Katana over the years, the company got it mostly right from the outset.
The Katana is an all-composite design consisting of a pair of fuselage halves joined longitudinally down the center of the airframe. The wings are similarly constructed, with an upper and lower half joined together after a lay-up and vacuum bagging process, a method that yields accurate, consistent airframe parts. After assembly, the parts are hot-cured in ovens.
The wingspar is carried through the fuselage in a robust box structure that also accommodates the spring steel landing gear. The pilots essentially sit on this structure which has proven enormously strong in the rough-and-tumble world of flight training. Its so strong, in fact, that we know of no in-flight structural break-ups of the Katana.
And even though the model has suffered its share of accidents, only two have been fatal. It is a very strong, well-built aircraft, in our estimation.
The wingspan is 35 feet, 6 inches, down from the 53-foot wings used on the motorgliders and the wingtips have a slight upturn to reduce drag. The Katana retained the high T-tail used on the motorgliders and it has a conventional elevator. Although T-tails have sometimes met with mixed reception due to perceived handling quirks and the nuisance of pre-flighting a flying surface thats 8 feet above ground, neither of these seem to trouble the Katana. The horizontal stab and elevator are just a bit above eye level so pre-flight isn’t a hassle.
One of the nicest things about the Katana is also one of not-so-nice things about the Katana: it has a forward opening-that is, rear-hinged-wrap around bubble canopy. This provides cockpit visibility unparalleled for a trainer-or for any aircraft, for that matter-but on a hot summer day, its an effective solar oven. If the airplane has been soaking in the heat for several hours, taxiing to the runway can be an exercise in endurance.
Although the POH advises against it, students and instructors learn to pop the canopy and hold it open a couple of inches during taxi in hot weather. Its easy enough to do and necessary to make taxi bearable. In cold weather, the payoff is that you’ll be toasty warm on a sunny day, even without using the heater, which is effective.
One aspect of the canopy that we don’t like is that if it isn’t latched correctly prior to takeoff or becomes unlatched in flight, the canopy pivots back and presents its entire surface to the relative wind. In other words, it becomes a giant, effective air brake. When we first saw the canopy, we worried that an inflight opening would cause the canopy to depart the airplane, perhaps taking the tail with it.
This appears not to be the case. There have been several instances of takeoff with the canopy unlatched and at least two in which the canopy opened during flight or just after takeoff. In one instance, the canopy departed but it didnt damage the tail.
In one canopy-open incident, the pilot landed on a dirt road off the end of the runway, in the other, the aircraft was crash landed into trees.
In neither case was the pilot seriously injured. According to Diamond, the aircraft will be marginally controllable with the canopy open during flight. The pilot who made the dirt-road landing reported that he had to hold full-forward stick to retain control with the canopy fully deployed in the breeze.
Conclusion: were still not crazy about that aft-hinged canopy but the accident record suggests that its not the safety hazard we imagined.
In later models, beginning with those made after January 1995, Diamond added a warning light to indicate when the canopy isn’t latched and it also improved the latching mechanism for ease of use.
Powerplant, Systems
The original North American Katana, known as the A1, was powered by a Rotax 912, a design decision that raised some eyebrows in the U.S. Rotax was and is well-known as a maker of quality two-cycle engines and it dominates the ultralight and light homebuilt market. But in a certified airplane?
Well, yes. The 912 variant used in the Katana is a certified aircraft engine under JAR/VLA rules in Europe and it was eventually given FAA Part 33 certification for use in the U.S. Later, in 2000, Diamond offered an engine upgrade to the 100-HP Rotax 912S and these models are known as Katana 100s.
Unlike the whiney two-cycles that gave Rotax a questionable name in the light aircraft field, the 912F is a four-cylinder, four-cycle dual-ignition genuine aircraft engine capable of delivering about 80 HP from only 73.9 cubic inches. It does this at relatively high RPM: 5800 RPM at the crankshaft, geared down to a 2550 RPM max at the prop, which is a constant speed Hoffman composite design for the early airplanes.
The Rotax has automotive-style CDI electronic ignition rather than conventional magnetos and to further distance it from the pack of conventional airplane engines, it is semi-watercooled. That means that the cylinder heads have a water jacket around them but the cylinder barrels themselves are air cooled. This has the advantage of making the engine more thermally stable so, theoretically, it should be less susceptible to the cylinder cracking that occasionally plagues trainer engines.
In reality, the Rotax has delivered generally good service, although we note a smattering of unexplained failures in the accident records and service difficulty reports. Because of complaints about anemic climb and because Rotax wasnt aggressive in follow-up development, Diamond switched to the Continental IO-240B at airframe number 331.
Initially, the Rotax engine was to have a 1000-hour TBO and that was later extended to 1200 hours. As of spring 2003, it was again extended to 1500 hours. Rather than a conventional overhaul, the plan was to exchange the entire engine/propeller set-up for a new replacement for a total cost of about $6000. TBO was eventually raised to 1200 hours but the Rotax replacement cost zoomed to $12,000. Given the TBO limitation, that made the engine costs a bit higher than for the conventional powerplant found in a Cessna 150 or Cessna 152.
System wise, the Katana is about as simple as they come. To save weight and for simplicity, there’s no nosewheel steering but a castoring nosewheel. Steering is via differential braking, as seems to be the trend in modern fixed-gear aircraft. Early Katanas had stiff pedal pressure for the main brakes and a shelf-like structure near the pedals that made it difficult for those large of feet to steer and brake the airplane. This was corrected in later models.
Flight controls are push-rod operated, except for the rudder, which has cables. The flaps are electric with two positions, one for take-off and one for landing. The flap switch is panel mounted with a position indicator light.
Trim is electric only, one of the things we don’t like about the airplane. There’s a rocker switch on the center console behind the throttle and this operates an anti-servo tab on the elevator. Unique among new aircraft, the Katana has a center stick which, in our view, is one of its strongest assets.
Weve always believed that students or pilots new to a type adapt more quickly to a center stick and we prefer this over yokes and the more recent innovation of a side controller. Significantly, even pilots who don’t like the Katana for other reasons seem to like the stick, nonetheless.
The fuel system is as simple as the airplane itself: a single aluminum tank located behind the seats and forming the floor of the baggage compartment. It holds 20.9 U.S. gallons and is filled from a cap located on the fuselage aft of the pilots seat. As a design feature, we don’t like the idea of putting fuel lines and hoses in the cockpit space, let alone the entire tank. In our view, the gasoline should be outside the people area, preferably in the wings.
That said, the Katanas internal tank hasnt proven to be a safety hazard. In the crash records we have examined, the tank has never been breached and as far we can tell, no Katanas have been involved in post-crash fires related to the fuel system. However, one service difficulty report we read reported on latent leaks in the tank seams. With age, this could become a safety issue.
The tank has a single shutoff valve located on the left side of the center console, near the pilots feet. The tank has a single sump drain located on the left side of the fuselage.
The Rotax Katanas are 12-volt airplanes with an external 40-amp alternator that provides plenty of power for the airplanes limited needs. The electronic ignition system is powered by its own separate alternator system built into the flywheel.
The airplane is all-electric but its worth noting that Katanas usually don’t have extensive avionics for the simple reason that they were never certified for IFR operation, something that many flight schools and owners have complained about. Diamond determined that the cost of providing lightning protection to meet IFR certification requirements would not have been offset by additional sales. While we agree, we also believe that the company has lost of a lot of sales because of the VFR limitation.
Even with this limitation, there’s plenty of room in the panel for avionics and instruments. The left-side panel has room for the standard six flight instruments and the avionics are located in a center stack that projects forward of the two left and right panels in the North American DA20. Engine instruments are located on the right panel and are large enough to read easily.
More Power
The Rotax powered Katana A1 is an easy-to-fly starter trainer, in our view, but many schools complained about one thing: poor climb performance. On a hot day with density altitude anything over 4000 or 5000 feet, a Rotax Katana can be a real dog, in our estimation. Initial climb rates may be in the 400 to 500 FPM range but at altitude, these may sag into the 300 FPM range. That makes practicing stalls or doing circuits and bumps a tedious chore.
Diamonds solution to this was to re-engine the airframe with a four-cylinder Continental IO-240B, with 125 HP. That had the advantage of providing more power and the benefits of fuel injection over the Rotaxs carbureted engine. (It had the disadvantage of introducing the hard starting sometimes associated with fuel injected engines but this yields to the proper starting technique.)
At the same time it introduced the Continental engine in 1998-in a new model known as the C1-Diamond made some changes to the basic airframe that squeezed an impressive 60 pounds out of the airframe. This accommodated the heavier Continental engine-246 pounds for the IO-240B versus 160 pounds for the Rotax. With the advent of the lighter airframe, the airplane got a re-designed horizontal stabilizer thats larger and has a reduced parts count, thanks to the elimination of the anti-servo tab. It also got slotted flaps in place of the A1s hinged flaps and the canopy latch was improved, as were the brake master cylinders. The wing sweep was tweaked by a half a degree.
Ergonomically, the instrument panel was moved higher and more forward, creating more knee room and the recline angle of the seatbacks was increased to improve comfort. This was a necessity, in our view, because although the fixed seats arent uncomfortable for a short training session, they can be excruciating on a long cross-country.
The heating and defrosting system was also improved with the C1 model and the airplane got additional instrumentation to include EGT, fuel flow and a larger tachometer.
There were some name changes, too. The C1 initially carried the Katana name but in 2000, Diamond switched gears and renamed the airplane the Eclipse and Evolution, with the former being the gussied up airplane intended for private owners and the Evolution the training model. The Eclipse has rear windows, pop out vents, wheel pants, inertial-reel harnesses and Garmin avionics versus Bendix/King products in the Evolution.
Performance, Handling
If Diamonds only goal was to produce a safe, easy-to-fly airplane, it hit a homerun with the Katana. In numerous flight trials, we have consistently found the Katana among the easiest airplanes of all time to fly. It has no bad control habits at all and the stick control geometry and design is excellent. The Katana has good static longitudinal stability, thus if a student tries to get out of bounds with pitch, the nose merely bobs up or down to compensate.
Stick-force-to-G is a bit on the light side, which is fine for a trainer, in our view. While we don’t think manhandling will ever pull the wings off a Katana, students should find it light enough to be easily mastered. The ailerons are effective with little adverse yaw, thus rudder input is of the light-pressure-on-the-pedal variety, not the stomp you encounter on heavier airplanes.
Stalls are quite gentle and even when weve aggravated them to provoke the airplane into something ugly, it simply wont comply. Although plenty of students have ham handed Katanas and broken plastic as result, none of these have been due to stalls or stall/spins, as far as we can tell from reviewing the Katanas accident record. The airplane is approved for spins, with the flaps up, something desireable in a trainer.
In addition to its training duties, the Katana is perfect for low-and-slow cruises across the countryside, with an emphasis on slow. To be fair, all trainers are slow so we cant bash the Katana unfairly. The Rotax A1 Katanas cruise in the 110 to 115 knot range, which makes them a bit faster than a Cessna 150. Expect fuel burns of 3.5 to 4.5 GPH which, in an age of $3-a-gallon avgas, helps keep operating costs low.
The Continental-powered version-C1, Eclipse and Evolution-are quite a bit faster, truing at 125 knots on 7.3 to 8.3 GPH. The Continental version also has a noticeably better climb rate, easily turning in an 800 FPM initial rate and holding 500 FPM or so at practice-area altitudes. If you don’t think thats a considerable improvement, you havent spent much time instructing.
As should be expected of a light trainer, Katanas have adequate but not generous payloads. Early A1s had empty weights of about 1160 pounds against a gross weight of 1609 pounds. That yields a useful load of about 450 pounds. Throw in full fuel and there’s barely enough payload left for two FAA 170-pounders. Obviously, a pair of 200-pounders up front wont cut it.
Allowable baggage weight is 44 pounds, which is quite generous considering that there’s very little space behind the seat for anything more than the proverbial hatbox and toothbrush. The Continental versions have a higher gross weight of 1764 pounds for a typical useful load of 600 pounds. That means full fuel and a pair of heavier pilots up front is a realistic option.
Maintenance, ADs
Diamond predicted that the Katana would be a low-maintenance airplane given its simple airframe and composite design. While thats true, the airplane isn’t without its foibles. None, however, are deal breakers, in our view. One early complaint concerned the overall serviceability of the Rotax engine. Its not like a Lycoming four-banger but is much more complex, requiring special skills and knowledge. The Continental engine is more to the liking of the typical mechanic but it is, of course, a less sophisticated engine.
Flightschools complain about brake wear and replacement, which is no surprise, since the airplane is steered with the brakes. Speaking of steering, we noted a number of service difficulty reports related to cracked or broken nose gear fork assemblies. One submitter opined that the assembly ought to be built more stoutly.
In the A1 aircraft, there were a number of reports of cracked spinners. One SDR reporter said he found nine cracked spinners on a fleet of nine aircraft. He suggested pilots pushing on the spinner during ground maneuvering was part of the problem.
We discovered several Rotax engine failures but nothing in this record suggests a generic problem with the engine. One had a rod failure just past the recommended TBO of 1200 hours.
Although the in-fuselage fuel tank hasnt been implicated in any accidents or fatalities, one mechanic reported that he found the tank cracked and leaking when it was removed to gain access to the rudder cables. There are no provisions to inspect the tank without removal and the submitter suggested this is a potential safety problem. In our view, a plastic tank would be a better idea.
We noted several instances of tachometer cable failures, at the swage where the cable joins the fitting at the tach. A new cable drive design has evidently addressed this. The Continental-powered airplanes have their own set of mechanical peccadilloes, chief among them a rash of exhaust stack cracking when the airplane first appeared with the new engine. This was also addressed with thicker-wall exhaust tubing.