April 4, 1998 The Diamond Katana

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by	Carl Marbach

About the Author ... Carl Marbach is a co-founder of AVweb and its Publisher. Carl is a 4,000-hour pilot, and commutes between homes in Boca Raton, Florida, and Aspen, Colorado, in his 1978 Aerostar 601P. Carl was the founder and CEO of Professional Press which published five computer magazines including DEC Professional. After Professional Press was acquired by a venture capital firm, Carl founded Internetwork Publishing Corporation and now devotes himself to the emerging field of electronic publishing via the Internet. A lifelong resident of Philadelphia until 1994, Carl and his wife Helen now live in Boca Raton, Florida.

It is a big decision. You have wanted to fly for some time and now you're going to do it. Excitement. Anticipation. You go to the airport and they take you out to the plane you are going to fulfill your dream of learning to fly in and… The plane is older than you are. It looks its age. It smells its age. It shakes, rattles and rolls. It squeaks. The plastic or Royalite is cracked and sun faded. Well, you get the idea.

One of the consequences of the dearth of light plane manufacturing is that the training fleet is aging fast. A plane used for training is ridden hard and put into the stable wet, day after day. They age fast. We finally have the promise of some life in the light aircraft market with Cessna and Piper building again, but their "trainers" are really stripped-down versions of regular four-place aircraft.

Something New

The Katana is sleek, sexy and modern-looking.

The good news is that I flew a modern, good looking trainer that will enhance the image of aviation and make a favorable impression on any new student at the airport. Diamond Aircraft's Katana DA20-A1 is a two seat, side-by-side low wing beauty that is one of those airplanes that look good standing still. Designed and manufactured by Diamond Aircraft Industries in London, Canada, the Katana is intended for primary flight training. It is constructed of advanced composites and has a conventional low wing, T-tail and tricycle landing gear. It is powered by a Bombardier Rotax 912F3, 81 horsepower four-cylinder engine with a recommended TBO of 1200 hours. Katana is also working on a Continental powered version, which would use the IO-240B producing 125 horsepower. The Rotax performed fine during our flight test, but Katana is anticipating the need for more power at higher elevations.

The Katana's Rotax 912 engine and controllable wood/composite prop.

The Rotax engine has several unusual features. It has two carburetors. By splitting the carburetor duties between the two, Rotax was able to use smaller carburetors and find room for them on top of this compact engine. The propeller is driven through a reduction gear box (2.27:1). This is transparent to the pilot who reads propeller RPMs on the tachometer. The engine also features an integral 20 amp alternator directly driven by the crankshaft and a 40-amp alternator driven off the pulley that is mounted to the propeller drive flange. The 20-amp alternator is used exclusively to power the dual capacitance discharge ignition system while the 40 amp alternator powers avionics, instruments and electrical accessories. There is no vacuum system and all the instruments are electrically driven. There is no priming system for this engine, but there is a choke (!) which is used for cold starting only. There is no mixture control, the carburetors are automatically altitude compensated.

The propeller is a hydraulically controlled constant speed with two blades. The prop blades are of wood core construction with composite skins and aluminum or polycarbonate bonding edge inserts. There are really only two settings for the prop: Take off (full RPM) and cruise (2400 RPM) making it simple enough even for a student pilot.

Plastic, Not Aluminum

Katana's composite wing spar. The red dot is the spar over-temperature indicator. (Oddly enough, all-red means okay.)

The aircraft itself is of Glass-Reinforced Plastic (GRP) construction with local Carbon-Reinforced Plastic (CRP) in high stress areas. The Stressed fuselage skin primarily made of a single GRP laminate with local GRP/PVC foam/GRP sandwich construction to increase stiffness and reduce noise. It looks and feels tough. The seats are made of GRP and fixed in position. For different length legs the rudder pedals are adjustable. I found this to be the most undesirable part of the airplane- more about that later. The main wing spar is an I-section spar constructed of CRP spar caps that are joined with a GRP/foam sandwich spar web. I've seen less formidable I-beams holding up houses.

There have been rumors and claims about the instability of this construction in high ambient temperatures. The spar does have a temperature limitation of 55 C or 131 F. There is an indicator located on the rear portion of the spar that is accessible by lifting the flap between the two seat cushions. The indicator is visible through the cut out in the seat back shells and is a round indicator with the numerals "55" on it. When the temperature is below 55C the indicator is all red with the "55 barely visible, when the temperature of the spar rises above 55C then the red "55" is displayed on a black background. Diamond claims that the limit is very difficult to reach except on the hottest of desert heat days. I flew the plane under the South Florida sun at an outside temperature of 90F and the spar never got close to temperature limits. Based on what I saw, there should be no airport in the U.S. where you couldn't operate the DA20 even on the hottest day.

Katana's front office features stick controls.

Opening up the mostly Plexiglas canopy the interior looks like a modern sports car; That is, tight quarters, firm seats, neat looks and the smell of leather. "Let's take the Mazda Rx-7 up today", it seemed to be saying. The radio stack is neatly done in the middle of the panel, with engine instruments and circuit breakers on the right. In front of the pilot is the usual "T" layout of flight instruments. The Katana is not certified for IFR flight even though it looks equipped for it. Katana told us it was due to the lack of lightning protection. I know something about that.

As I mentioned before there is no mixture control, just the throttle and prop RPM along with carburetor heat and cabin heat (we didn't need that here in Florida). Flight controls are operated by a stick mounted in the floor between each pilot's legs. The stick is short and doesn't take up much room, but it gave me pause for thought as the last stick airplane I flew was a Cub and that was some time ago. (I needn't have worried.)

Let's Go Flying!

Time to fly the Katana (this is the fun part).

Okay, time to fly (The best part.) Pre-flight is straightforward excepting for the spar temperature check, which we already mentioned. The book says is only needs to be checked when the ambient temperature exceeds 100F. In the engine you have to check the coolant level as well as the oil quantity. There is one tank drain to check for water and the fuel is either on or off, no tank switching required. Once seated inside, you have to adjust the rudder pedals to fit your legs. Using the toe/foot brakes required a foot movement that I never quite mastered. A sort of swiveling of the ankle while holding the heal to the floor but not to high up on the pedals…..well, I got it to work but it never felt good and since the rest of the airplane seems so much in harmony with itself this trait stood out. The canopy can be held open with a latch for taxi but is closed for flight.

Starting the Rotax is a matter of electric fuel pump on, choke only if it is cold, cracking the throttle and turning the key/start switch. The small Rotax started so abruptly that it surprised me. It stops the same way; turn the key off and the engine stops immediately.

Starting to taxi takes a very small amount of throttle, as the airplane weighs only 1600 pounds fully loaded. Steering, via differential braking using the rudder pedals was awkward and I had some trouble getting my feet in the right position to use the rudder/brakes. I did get better after some practice. The brakes and ground steering turned out to be the only real item that I found unpleasant about the Katana.

A normal run-up, check the mags, cycle the prop and carb heat, flaps to T/O position, close the canopy, throttle up and release the brakes. At 51 Knots rotate and accelerate to climb speed of 60 knots. At first the little stick is easy to over control because it is stiff and the little trainer reacts quickly and positively to control inputs. It stayed stiff but I got used to the quick response, after a while it began to make me feel like I was very "connected" to the airplane.

Visibility is exceptional in the Katana.

Climb at full power, retract the flaps and set the prop at 2400 RPMs and hold best rate of climb (Vy) of 69 knots. The Katana climbs smoothly at about 500-600 fpm with two of us aboard and almost full fuel. Not spectacular, but very comfortable. It is easy to see why at higher density altitudes or mountainous terrain the higher horsepower continental version might be a better choice. Here at sea level, even if it is hot (90F) the Rotax's performance is fine. The aircraft has exceptional stability, some due to the high friction in the stick and some due to the design; put it in an attitude and it stays there. This is fine training for a student. When you enter a turn, neutralize the stick and the aircraft stays banked. No tendencies to shallow out or increase the bank. This feature is probably what caused me to hit our own propwash on my first steep 360 turn. At the time I thought it might be the pilot, but on further reflection I realize that the airplane had more to do with it. Noise levels are reasonable, and the built-in standard intercom is a feature I'd like to see in all trainers.

Putting It Through Its Paces

Stalls give plenty of aerodynamic warning and the long wing stays fully controllable throughout. The Katana stalls at about 40 knots straight and level and about 55 knots in a 45-degree bank. Departure stalls demonstrate the wing drop you would expect and the excellent visibility afforded by the low wing and the bubble canopy make the experience very graphic as the sky, ground and the wings all stay visible throughout the maneuver. The Katana is approved for spins. In other trainers I have flown, the high wing or the cabin roof limit your visibility during attitude maneuvers and obstruct your vision enough to make it hard to visualize where everything is in relation to the sky and ground. The Katana has such great visibility because of the low wing, bubble canopy and low glareshield that gives flying it a very open and airy experience. In fact, flying a plane with this kind of visibility is lots of Fun (with a capital F).

While not exactly designed for long cross-country work, the Katana will get you there in a reasonable time. Cruise speed varies between 110 and 120 knots and the little Rotax burns 3.5-4.0 GPH, very economical. For even more economy, the engine is certified to run on automotive gas with a minimum octane of 90 and no added ethanol. With the great visibility, solid stability and good speed, the Katana would be fun to fly from here to there. A student would also have the advantage of good ground visibility to help in his first cross-country trips. Stated range in the flight manual is 523 nm but we didn't test that.

After some airwork it was time to see how the Katana handled close to the ground. Reduce power (remember carburetor heat if needed) and the Katana stars down without much wind noise due to the smooth airflow over the rounded canopy. For landing the electric fuel pump is on, and T/O flaps (15 degrees) are used to help slow down and go down. Approaching at 57 knots is comfortably above stall and gives good control response. I would guess that a student would be overcontrolling in this area of flight, I like to see students correcting wings down with a rapid response particularly as we get close to the ground, but the Katana is very responsive and will take some getting used to. It is touchier in pitch than roll and once again, the short stick will take some getting used to. As a personal preference, I like sticks; they take up less room, get in the way less and are more intuitive. An airplane is not a car and really doesn't need a wheel.

I brought the Katana close to the runway and held it there just waiting. Without much float, and with good deceleration with full flaps the trainer touched down more smoothly than my first landing ought to have been- once again while I'm good, I'm not that good, the airplane had lots to do with it. Roll out was short and we taxied back for some short field takeoffs and landings. I pushed the envelop a little for a short/soft field takeoff keeping the stick back and then lowering the nose when the airplane first lifted off. This can be tricky for students, but the Katana seemed to feel as solid here as it did everywhere else.

Approaching at 50 knots instead of 57 knots still left plenty of margin before a stall but resulted in less float and a more positive touchdown (read: not a squeaker). Actual touchdown speeds are very low and the aircraft can be stopped in a very short distance.

One Fun Airplane...

The Diamond Katana: one FUN airplane!

Flying the Diamond Katana is fun. It looks good and feels the same way. The Rotax engine starts quickly and easily and has good throttle response. The controls are stiff but very effective. It is easy to fly and has lots of visibility. It might take a student some time to handle the rudder/brake interaction and the quick controls also take some time to get used to. The airplane says, "let's fly!" just sitting on the ramp.

Diamond claims that the airplane is extremely easy to maintain. 100 hour inspections are quick and easy to do and the Rotax engine is inexpensive to maintain and overhaul. Airport or flight school operators should be able to look forward to reduced operating costs over older trainers they may have been using.

The Katana has a clear edge over older trainers but it is less clear how it will fare against the new Cessna 172s or other established trainers, which may go into new production. That's why there is still Ford and General Motors; people's opinions differ on lots of subjects, cars and airplane trainers being only two of them. There is definitely room in the market for a trainer that looks and flies as good as this one does. The Katana gives you the feeling of flying with its great visibility and quick controls. If the airplane is flown 200 hours a year, lower-operating costs may also factor into the equation.

If we could get student starts to increase with the GA Team 2000 program, the EAA's Young Eagles program and others, the market for new trainers would heat up. There may be some "cat chasing his own tail" going on, because if we had more attractive training aircraft we might attract more students which might require more attractive training aircraft and so on. No one buys Mooney, a high performance Piper, or any advanced aircraft without learning to fly first. Making that experience a good one is important to the future of General Aviation. The Diamond Katana is a good start.